Moisture detection system

BACKGROUND INFORMATION

1. Field:

0001The present disclosure relates generally to aircraft and, in particular, to detecting moisture in porous materials in aircraft. Still more particularly, the present disclosure relates to a method, apparatus, and system for detecting moisture in panels in aircraft.

2. Background:

0002Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Composite materials are used in aircraft to decrease the weight of the aircraft. This decreased weight improves performance features such as payload capacities and fuel efficiencies. Further, composite materials provide a longer service life for various components in an aircraft.

0003For example, composite parts such as composite panels are used in aircraft for walls, closets, galleys, and other structures or monuments in aircraft such as commercial airplanes. These composite panels may be composite sandwich panels that are comprised of a core between two face sheets. The core may be a honeycomb core, a foam core, or some other suitable type of core. Further, in some cases, a decorative laminate may be placed on a face sheet or may be used as the face sheet. In this manner, the composite sandwich panel may have logos, color, or designs for a particular airline.

0004One problem with these composite sandwich panels and other structures that have porous materials is moisture. Moisture in a composite sandwich panel can cause bubbling. Bubbling is aesthetically undesirable especially when the bubbling occurs in locations visible to passengers, such as in the passenger cabin within a commercial airplane.

0005This occurrence in a structure in the passenger cabin is a problem that can disrupt the delivery of a commercial airplanes when bubbling is discovered. Further, the discovery of bubbling in composite sandwich panels during production of a commercial airplane may result in delays. Reworking composite sandwich panels with bubbling increases the time and expense for producing an airplane. Disruption in the production line may occur.

0006Further, moisture within a composite sandwich panel may not immediately manifest itself in the form of bubbling. When bubbling is discovered, rework may be performed.

0007Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues. For example, it would be desirable to have a method and apparatus that overcome a limitation with detecting moisture in porous structures such as composite sandwich panels.

SUMMARY

0008An example of the present disclosure provides a moisture detection system. The moisture detection system is comprised of an electromagnetic radiation system, an infrared detector system, and a controller in communication with the electromagnetic radiation system and the infrared detector system. The controller is configured to control the electromagnetic radiation system to transmit a pulse of electromagnetic radiation into a composite sandwich pane. The pulse of electromagnetic radiation has a number of wavelengths that is absorbed by water molecules. The controller is configured to control the infrared detector system to detect an amount of infrared radiation in response to transmitting the pulse of electromagnetic radiation into the composite sandwich panel using a time window. The time window is selected to detect the amount of infrared radiation when the pulse of electromagnetic radiation heats the composite sandwich panel such that the infrared detector system detects the amount of infrared radiation in the composite sandwich panel when the composite sandwich panel is heated by the pulse of electromagnetic radiation. The amount of infrared radiation indicates a level of moisture in the composite sandwich panel.

0009Another embodiment of the present disclosure provides a method for an aerospace vehicle. A pulse of electromagnetic radiation is transmitted into the composite sandwich panel such that the composite sandwich panel is heated above an ambient temperature. An amount of infrared radiation generated in the composite sandwich panel is detected in response to transmitting the pulse of electromagnetic radiation into the composite sandwich panel using a time window selected to detect the amount of infrared radiation when the pulse of electromagnetic radiation heats the composite sandwich panel. The amount of infrared radiation detected indicates a level of moisture in the composite sandwich panel.

0010Yet another embodiment of the present disclosure provides a moisture detection system. The moisture detection system is comprised of an electromagnetic radiation system an infrared detector system, and a controller. The controller is configured to control the electromagnetic radiation system to transmit a pulse of electromagnetic radiation into a porous material in which a pulse of electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules. The controller is configured to control the infrared detector system to detect the amount of infrared radiation in the porous material in response to transmitting the pulse of electromagnetic radiation into the porous material using a time window that captures when the pulse of electromagnetic radiation heats the porous material such that the infrared detector system detects the amount of infrared radiation in the porous material when the porous material is heated by the pulse of electromagnetic radiation. The controller is configured to identify a level of moisture in the porous material using an amount of energy in the pulse of electromagnetic radiation transmitted and the amount of infrared radiation detected.

0011Another embodiment of the present disclosure provides a method for detecting moisture in a porous material. Electromagnetic radiation is transmitted into the porous material, wherein an electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules. An amount of infrared radiation in the porous material is detected in response to transmitting the electromagnetic radiation into a composite sandwich panel using a time window selected to detect the amount of infrared radiation when the electromagnetic radiation heats the porous material. A level of moisture in the porous material is identified using an amount of energy in the electromagnetic radiation transmitted and the amount of infrared radiation detected.

0012The features and functions can be achieved independently in various examples of the present disclosure or may be combined in yet other examples in which further details can be seen with reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0013The novel features believed characteristic of the illustrative examples are set forth in the appended claims. The illustrative examples, however, as well as a preferred mode of use, further objectives and features thereof, will best be understood by reference to the following detailed description of an illustrative example of the present disclosure when read in conjunction with the accompanying drawings, wherein: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001"><b>Figure 1</b></figref> is an illustration of a block diagram of a moisture detection environment in accordance with an illustrative example;</li><li><figref idref="f0002"><b>Figure 2</b></figref> is an illustration of a block diagram of a moisture detection environment in accordance with an illustrative example;</li><li><figref idref="f0003"><b>Figure 3</b></figref> is an illustration of a moisture detection system in accordance with the illustrative example;</li><li><figref idref="f0004"><b>Figure 4</b></figref> is an illustration of a phased array in accordance with an illustrative example;</li><li><figref idref="f0005"><b>Figure 5</b></figref> is an illustration of a timing diagram in accordance with an illustrative example;</li><li><figref idref="f0006"><b>Figure 6</b></figref> is an illustration of a table of material parameters in accordance with an illustrative example;</li><li><figref idref="f0006"><b>Figure 7</b></figref> is an illustration of a flowchart of a process for detecting moisture in a porous material in accordance with an illustrative example;</li><li><figref idref="f0007"><b>Figure 8</b></figref> is an illustration of a flowchart of a process for detecting moisture in a composite sandwich panel for an aerospace vehicle in accordance with an illustrative example;</li><li><figref idref="f0007"><b>Figure 9</b></figref> is an illustration of a flowchart of a process for detecting moisture in a porous material in accordance with an illustrative example;</li><li><figref idref="f0008"><b>Figure 10</b></figref> is an illustration of a flowchart of a process for detecting moisture in detecting moisture in a composite sandwich panel for an aerospace vehicle in accordance with an illustrative example;</li><li><figref idref="f0009"><b>Figure 11</b></figref> is an illustration of a flowchart of a process for managing actions performed with respect to a porous material in response to detecting the level moisture in accordance with an illustrative example;</li><li><figref idref="f0010"><b>Figure 12</b></figref> is an illustration of a block diagram of a data processing system in accordance with an illustrative example;</li><li><figref idref="f0011"><b>Figure 13</b></figref> is an illustration of a block diagram of an aircraft manufacturing and service method in accordance with an illustrative example;</li><li><figref idref="f0011"><b>Figure 14</b></figref> is an illustration of a block diagram of an aircraft in which an illustrative example may be implemented; and</li><li><figref idref="f0011"><b>Figure 15</b></figref> is an illustration of a block diagram of a product management system in accordance with an illustrative example.</li></ul>

DETAILED DESCRIPTION

0014The illustrative examples recognize and take into account one or more different considerations. For example, the illustrative examples recognize and take into account that measuring moisture in composite sandwich structures that employ foam or honeycomb cores may be more difficult than desired. The illustrative examples recognize and take into account that current techniques for moisture detection are unable to measure a level of moisture in a composite sandwich structure. The illustrative examples recognize and take into account that current techniques are unable to map the level of moisture in a composite sandwich structure.

0015Thus, the illustrative examples provide a method, apparatus, and system for detecting moisture. In one illustrative example, a moisture detection system comprises an electromagnetic radiation system, an infrared detector system, and a controller. The electromagnetic radiation system is configured to transmit electromagnetic radiation, and the infrared detector system is configured to detect an amount of infrared energy.

0016The controller is configured to control the electromagnetic radiation system to transmit a pulse of electromagnetic radiation into the porous material, in which the pulse of the electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules. The controller also controls the infrared detector system to detect the amount of infrared energy in the porous material in response to transmitting the electromagnetic radiation into the porous material using a time window that captures when the electromagnetic radiation heats the porous material such that the infrared detector system detects an amount of the infrared energy in the porous material when the porous material is heated by the pulse of electromagnetic radiation. The controller identifies a level of moisture in the porous material using an amount of energy in the electromagnetic radiation transmitted and the amount of infrared energy detected.

0017In another illustrative example, a moisture detection system comprises a phased array, an infrared detector system, and a controller. The phased array is configured to emit a pulse of an electromagnetic radiation beam. The pulse of the electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules. The infrared detector system is configured to detect an amount of infrared energy. The amount of infrared energy indicates a level of moisture in a porous material.

0018The controller is configured to control the phased array by beam steering the pulse of the electromagnetic radiation beam to an area on the porous material, and synchronize timing of the pulse of the electromagnetic radiation beam to heat the porous material with a time window in the infrared detector system to detect the amount of infrared energy. The controller is configured to control the infrared detector system to detect the amount of the infrared energy in an area on the porous material in the time window when the porous material is heated by the pulse of the electromagnetic radiation beam.

0019With reference now to the figures, and in particular, with reference to <figref idref="f0001"><b>Figure 1</b></figref><b>,</b> an illustration of a block diagram of a moisture detection environment is depicted in accordance with an illustrative example. In this illustrative example, moisture detection environment <b>100</b> includes moisture detection system <b>102,</b> which operates to inspect porous material <b>104.</b> In this example, porous material <b>104</b> can be inspected for a level of moisture <b>106.</b> As depicted, the level of moisture <b>106</b> may indicate a presence or absence of moisture <b>106.</b> When moisture <b>106</b> is present, the level of moisture <b>106</b> can also indicate how much moisture <b>106</b> is detected.

0020In this illustrative example, porous material <b>104</b> is a material having spaces, holes, or other types of channels or voids through which a liquid or gas can pass. For example, porous material <b>104</b> can be an open cell foam or honeycomb structure. In another example, porous material <b>104</b> may be a closed cell foam in which some cells are not closed and allows a gas or liquid to pass.

0021In the illustrative example, porous material <b>104</b> takes the form of composite sandwich panel <b>108.</b> Composite sandwich panel <b>108</b> comprises a core located between a first face sheet and a second face sheet. The core may take a number of different forms. For example, the core can be selected from at least one of a foam core, an open cell foam core, a closed cell foam core, a honeycomb core, or some other suitable type of core.

0022As used herein, the phrase "at least one of," when used with a list of items, means different combinations of one or more of the listed items may be used, and only one of each item in the list may be needed. In other words, "at least one of" means any combination of items and number of items may be used from the list, but not all of the items in the list are required. The item may be a particular object, a thing, or a category.

0023For example, without limitation, "at least one of item A, item B, or item C" may include item A, item A and item B, or item B. This example also may include item A, item B, and item C or item B and item C. Of course, any combinations of these items may be present. In some illustrative examples, "at least one of" may be, for example, without limitation, two of item A; one of item B; and ten of item C; four of item B and seven of item C; or other suitable combinations.

0024As depicted, the type of core within composite sandwich panel <b>108</b> can be different in different parts of composite sandwich panel <b>108.</b> For example, a portion of composite sandwich panel <b>108</b> may be a honeycomb core in one area of composite sandwich panel <b>108</b> and a foam core in another area of composite sandwich panel <b>108.</b> In one illustrative example, composite sandwich panel <b>108</b> is for use in an aerospace vehicle selected from one of an airplane, an aircraft, a commercial airplane, a rotorcraft, a spacecraft, a commercial spacecraft, a space plane, or some other type of aerospace vehicle.

0025In this illustrative example, moisture detection system <b>102</b> is comprised of a number of different components. As depicted, moisture detection system <b>102</b> includes electromagnetic radiation system <b>110,</b> infrared detector system <b>112,</b> and controller <b>114.</b>

0026Electromagnetic radiation system <b>110</b> transmits pulse of electromagnetic radiation <b>116.</b> In this illustrative example, pulse of electromagnetic radiation <b>116</b> has a number of frequencies <b>118</b> selected from about 300 MHz to about 300 GHz.

0027As used herein, "a number of," when used in reference to items means one or more items. For example, "a number of frequencies <b>118"</b> is one or more of frequencies <b>118.</b> In this example, pulse of electromagnetic radiation <b>116</b> takes the form of pulse of microwaves. Pulse of electromagnetic radiation <b>116</b> is the transmission of electromagnetic radiation for a period of time in contrast to transmitting electromagnetic radiation continuously while operating moisture detection system <b>102.</b>

0028In this illustrative example, infrared detector system <b>112</b> is configured to detect an amount of infrared radiation <b>122.</b> As depicted, infrared radiation <b>122</b> has a longer wavelength than those of visible light. In this illustrative example, infrared radiation <b>122</b> is generated when pulse of electromagnetic radiation <b>116</b> encounters water molecules <b>124</b> in moisture <b>106.</b>

0029Infrared detector system <b>112</b> includes a number of different types of detectors. For example, infrared detector system <b>112</b> may include at least one of an infrared sensor, a thermal sensor, a photodetector, a thermographic camera, an infrared camera, a thermal imaging camera, or some other suitable type of detector.

0030In this illustrative example, controller <b>114</b> is in communication with electromagnetic radiation system <b>110</b> and infrared detector system <b>112.</b> Controller <b>114</b> is configured to control electromagnetic radiation system <b>110</b> to transmit pulse of electromagnetic radiation <b>116</b> into composite sandwich panel <b>108.</b> Pulse of electromagnetic radiation <b>116</b> has a number of wavelengths <b>126</b> such that pulse of electromagnetic radiation <b>116</b> is absorbed water molecules <b>124</b> in moisture <b>106</b> in composite sandwich panel <b>108.</b>

0031As depicted, controller <b>114</b> is configured to select the number of frequencies <b>118</b> for pulse of electromagnetic radiation <b>116</b> based on desired depth <b>132</b> at which pulse of electromagnetic radiation <b>116</b> penetrates composite sandwich panel <b>108.</b> The level of penetration affects the depth at which heating within composite sandwich panel <b>108</b> occurs.

0032Further, controller <b>114</b> can be configured to control electromagnetic radiation system <b>110</b> to transmit pulse of electromagnetic radiation <b>116</b> through lens antenna <b>140</b> to form electromagnetic radiation beam <b>142</b> directed at composite sandwich panel <b>108</b> such that composite sandwich panel <b>108</b> is heated above the ambient temperature for composite sandwich panel <b>108.</b>

0033Controller <b>114</b> also controls infrared detector system <b>112</b> to detect an amount of infrared radiation <b>122</b> generated in response to transmitting pulse of electromagnetic radiation <b>116</b> into composite sandwich panel <b>108</b> using time window <b>128.</b> As depicted, time window <b>128</b> is selected to detect the amount of infrared radiation <b>122</b> when pulse of electromagnetic radiation <b>116</b> heats composite sandwich panel <b>108</b> such that infrared detector system <b>112</b> detects an amount of infrared radiation <b>122</b> in composite sandwich panel <b>108</b> when composite sandwich panel <b>108</b> is heated by pulse of electromagnetic radiation <b>116.</b> The amount of infrared radiation <b>122</b> indicates a level of moisture <b>106</b> in composite sandwich panel <b>108.</b>

0034In this illustrative example, time window <b>128</b> is selected to detect the amount of infrared radiation <b>122</b> in response to pulse of electromagnetic radiation <b>116</b> heating composite sandwich panel <b>108</b> such that a sensitivity of infrared detector system <b>112</b> is increased. This increase can occur by selecting width of time window <b>128</b> such that time window <b>128</b> encompasses all of pulse of electromagnetic radiation <b>116.</b>

0035Controller <b>114</b> can be configured to control infrared detector system <b>112</b> to detect an amount of background infrared radiation <b>130</b> prior to electromagnetic radiation system <b>110</b> transmitting pulse of electromagnetic radiation <b>116.</b> The amount of background infrared radiation <b>130</b> is the amount of infrared radiation <b>122</b> that is present without pulse of electromagnetic radiation <b>116</b> being directed into composite sandwich panel <b>108.</b> Background infrared radiation <b>130</b> can be subtracted from the amount of infrared radiation <b>122</b> detected to determine infrared radiation <b>122</b> resulting from applying pulse of electromagnetic radiation <b>116</b> to composite sandwich panel <b>108.</b>

0036Background infrared radiation <b>130</b> can be measured as an ambient temperature for composite sandwich panel <b>108.</b> This ambient temperature may vary depending on the environment in which composite sandwich panel <b>108</b> is located. For example, composite sandwich panel <b>108</b> may be located inside the hangar, within an aircraft, or some other suitable location. Depending on the size of composite sandwich panel <b>108,</b> a portion of the panel may be located inside of a building while another portion may be located outside of the building.

0037As depicted, controller <b>114</b> is configured to determine the level of moisture <b>106</b> in composite sandwich panel <b>108.</b> In this example, the level of moisture <b>106</b> is determined using the amount of infrared radiation <b>122</b> detected and energy <b>120</b> for pulse of electromagnetic radiation <b>116</b> sent into composite sandwich panel <b>108.</b>

0038Controller <b>114</b> is configured to generate visualization <b>134</b> of infrared radiation <b>122</b> for composite sandwich panel <b>108</b> using the amount of infrared radiation <b>122</b> detected by infrared detector system <b>112</b> within time window <b>128.</b> Visualization <b>134</b> can be selected from at least one of a thermal map, a thermal image, or some other visualization of infrared radiation <b>122</b> for composite sandwich panel <b>108.</b> Visualization <b>134</b> allows a user or other person to see where moisture <b>106</b> may be located within composite sandwich panel <b>108.</b>

0039One or more solutions are present that overcome a problem with detecting moisture in porous materials. As a result, one or more technical solutions may provide a technical effect of determining a level of moisture <b>106</b> rather than merely detecting whether moisture <b>106</b> is present.

0040As a result, computer system <b>144</b> in this illustrative example operates as a special purpose computer system in which controller <b>114</b> in computer system <b>144</b> enables detecting a level of moisture <b>106</b> in porous material <b>104.</b> In particular, controller <b>114</b> transforms computer system <b>144</b> into a special purpose computer system as compared to currently available general computer systems that do not have controller <b>114.</b>

0041With reference to <figref idref="f0002"><b>Figure 2</b></figref><b>,</b> another illustration of a block diagram of a moisture detection environment is depicted in accordance with an illustrative example. In this illustrative example, moisture detection environment <b>200</b> includes moisture detection system <b>202</b> configured to inspect porous material <b>204</b> for moisture <b>206.</b> Moisture detection system <b>202</b> can be utilized to inspect porous material <b>204</b> for a level of moisture <b>206.</b> As depicted, porous material <b>204</b> takes the form of composite sandwich panel <b>208.</b>

0042In this illustrative example, moisture detection system <b>202</b> is comprised of a number of different components. As depicted, moisture detection system <b>202</b> includes phased array <b>210,</b> infrared detector system <b>212,</b> and controller <b>214.</b>

0043As depicted, phased array <b>210</b> is an electronically scanned array and another manner in which a beam can be formed in addition to or in place of using a lens antenna. Phased array <b>210</b> transmits electromagnetic radiation beam <b>216</b> as pulse <b>218.</b> In this illustrative example, phased array <b>210</b> can be an array of antennas controlled to create electromagnetic radiation beam <b>216,</b> which may be radio frequency waves that can be electronically steered in different directions without physically moving the antennas in phased array <b>210.</b>

0044In this illustrative example, pulse <b>218</b> of electromagnetic radiation beam <b>216</b> has a number of frequencies <b>220</b> selected from about 300 MHz to about 300 GHz. As depicted, controller <b>214</b> can select the number of frequencies <b>220</b> for pulse <b>218</b> of electromagnetic radiation beam <b>216</b> based on desired depth <b>232</b> at which pulse <b>218</b> of electromagnetic radiation beam <b>216</b> penetrates composite sandwich panel <b>208.</b>

0045As depicted, infrared detector system <b>212</b> is configured to detect an amount of infrared radiation <b>222.</b> Infrared detector system <b>212</b> may be implemented in a similar fashion to infrared detector system <b>112</b> in <figref idref="f0001"><b>Figure 1</b></figref><b>.</b>

0046Controller <b>214</b> is in communication with phased array <b>210</b> and infrared detector system <b>212.</b> Controller <b>214</b> is located in computer system <b>215.</b> As depicted, controller <b>214</b> is configured to control phased array <b>210</b> to beam steer pulse <b>218</b> of electromagnetic radiation beam <b>216</b> transmitted from phased array <b>210</b> to composite sandwich panel <b>208.</b> Controller <b>214</b> is also configured to synchronize timing <b>226</b> of pulse <b>218</b> of electromagnetic radiation beam <b>224</b> to heat composite sandwich panel <b>208</b> with time window <b>228</b> used by infrared detector system <b>212</b> to detect the amount of infrared radiation <b>222.</b> Synchronizing timing <b>226</b> of pulse <b>218</b> also may include the scanning or movement of pulse <b>218</b> in addition to the duration of pulse <b>218</b> in these illustrative examples.

0047The synchronization increases the sensitivity in images of infrared radiation <b>222.</b> For example, controller <b>214</b> is configured to control infrared detector system <b>212</b> to detect the amount of infrared radiation <b>222</b> in composite sandwich panel <b>208</b> within time window <b>228</b> when composite sandwich panel <b>208</b> is heated by pulse <b>218</b> of electromagnetic radiation beam <b>216.</b>

0048In steering pulse <b>218</b> of electromagnetic radiation beam <b>216,</b> controller <b>214</b> controls phased array <b>210</b> to beam steer pulse <b>218</b> to cover area <b>230</b> on composite sandwich panel <b>208.</b> Controller <b>214</b> controls infrared detector system <b>212</b> to detect the amount of infrared radiation <b>222</b> radiating from area <b>230</b> within time window <b>228</b> when pulse <b>218</b> of electromagnetic radiation beam <b>216</b> heats area <b>230</b> on composite sandwich panel <b>208.</b> In the illustrative example, time window <b>228</b> is selected to detect the amount of infrared radiation <b>222</b> in response to pulse <b>218</b> of electromagnetic radiation beam <b>216</b> heating composite sandwich panel <b>208</b> such that a sensitivity of infrared detector system <b>212</b> is increased.

0049With the use of phased array <b>210,</b> the accuracy in determining area <b>230</b> increases as compared to using other types of radiation emission systems. With phased array <b>210,</b> beam steering may be performed in a manner in which the location of the beam is more accurately known. As a result, determining energy <b>234</b> applied to area <b>230</b> is more accurate.

0050In this illustrative example, controller <b>214</b> is configured to determine the level of moisture <b>206</b> in composite sandwich panel <b>208</b> using the amount of infrared radiation <b>222</b> detected in area <b>230</b> and energy <b>234</b> in pulse <b>218</b> of electromagnetic radiation beam <b>216</b> sent into area <b>230</b> on composite sandwich panel <b>208.</b>

0051Controller <b>214</b> can be configured to control infrared detector system <b>212</b> to detect an amount of background infrared radiation <b>236</b> prior to phased array <b>210</b> transmitting pulse <b>218</b> of electromagnetic radiation beam <b>216.</b> The amount of background infrared radiation <b>236</b> is the amount of infrared radiation <b>222</b> that is present without pulse <b>218</b> of electromagnetic radiation beam <b>216</b> being directed into composite sandwich panel <b>208.</b> Background infrared radiation <b>236</b> can be subtracted from the amount of infrared radiation <b>222</b> detected to determine infrared radiation <b>222</b> resulting from applying pulse <b>218</b> of electromagnetic radiation beam <b>216</b> to composite sandwich panel <b>208.</b>

0052Additionally, controller <b>214</b> is configured to generate visualization <b>238</b> of the amount of infrared radiation <b>222</b> detected in composite sandwich panel <b>208.</b> In this illustrative example, visualization <b>238</b> may be selected from at least one of a thermal image, a thermal map, or some other type of visualization. In the illustrative example, controller <b>214</b> is configured to generate a map of moisture <b>106</b> within composite sandwich panel <b>108</b> using visualization <b>238,</b> such as a thermal map or a thermal image.

0053One or more solutions are present that overcome a problem with detecting moisture in porous structures such as composite sandwich panels. As a result, one or more technical solutions may provide an ability to detect moisture in a porous material including a composite sandwich panel. The controller controls the operation of an electromagnetic radiation system and an infrared detector system to detect a level of moisture in an area using a time window. The selection of the time window can increase the sensitivity of the infrared detector system.

0054As a result, computer system <b>215</b> in this illustrative example operates as a special purpose computer system in which controller <b>214</b> in computer system <b>215</b> enables controlling the operation of an electromagnetic radiation system and an infrared detector system to detect a level of moisture in an area using a time window. In particular, controller <b>114</b> transforms computer system <b>215</b> into a special purpose computer system, as compared to currently available general computer systems that do not have controller <b>214.</b>

0055Controller <b>114</b> in <figref idref="f0001"><b>Figure 1</b></figref> and controller <b>214</b> in <figref idref="f0002"><b>Figure 2</b></figref><b>,</b> may be implemented in software, hardware, firmware, or a combination thereof. When software is used, the operations performed by these controllers may be implemented in program code configured to run on hardware, such as a processor unit. When firmware is used, the operations performed by controller <b>114</b> and controller <b>214</b> may be implemented in program code and data and stored in persistent memory to run on a processor unit. When hardware is employed, the hardware may include circuits that operate to perform the operations in controller <b>114</b> and controller <b>214.</b>

0056The hardware can take a form selected from at least one of a circuit system, an integrated circuit, an application specific integrated circuit (ASIC), a programmable logic device, or some other suitable type of hardware configured to perform a number of operations. With a programmable logic device, the device can be configured to perform the number of operations. The device may be reconfigured at a later time or may be permanently configured to perform the number of operations. Programmable logic devices include, for example, a programmable logic array, a programmable array logic, a field programmable logic array, a field programmable gate array, and other suitable hardware devices. Additionally, the processes may be implemented in organic components integrated with inorganic components and may be comprised entirely of organic components excluding a human being. For example, the processes may be implemented as circuits in organic semiconductors.

0057As depicted, controller <b>114</b> is located in computer system <b>144.</b> In this example, computer system <b>144</b> is a physical hardware system and includes one or more data processing systems. When more than one data processing system is present, those data processing systems are in communication with each other using a communications medium. The communications medium may be a network. The data processing systems may be selected from at least one of a computer, a server computer, a tablet, or some other suitable data processing system.

0058The illustration of moisture detection environment <b>100</b> in <figref idref="f0001"><b>Figure 1</b></figref> and moisture detection environment <b>200</b> in <figref idref="f0002"><b>Figure 2</b></figref> is not meant to imply physical or architectural limitations to the manner in which an illustrative example may be implemented. Other components in addition to or in place of the ones illustrated may be used. Some components may be unnecessary. Also, the blocks are presented to illustrate some functional components. One or more of these blocks may be combined, divided, or combined and divided into different blocks when implemented in an illustrative example.

0059For example, composite sandwich panel <b>108</b> can have two cores between the first face sheet and the second face sheet. These two cores can be separated from each other by a layer similar to the face sheets. As another example, moisture detection system <b>102</b> can be used to detect a level of moisture <b>106</b> and other types of porous material <b>104</b> other than composite sandwich panel <b>108.</b> Other types of porous material <b>104</b> may include, for example, a thermal protection system (TPS) on the exterior of a missile, a rocket, or a space vehicle. The thermal protection system is porous and can contain moisture.

0060Composite sandwich panel <b>108</b> and composite sandwich panel <b>208</b> can be utilized in other platforms other than an aerospace vehicle. The platform may be, for example, a mobile platform, a stationary platform, a land-based structure, an aquatic-based structure, and a space-based structure. More specifically, the platform may be a surface ship, a tank, a personnel carrier, a train, a space station, a satellite, a submarine, an automobile, a power plant, a bridge, a dam, a house, a manufacturing facility, a building, and other suitable platforms.

0061The power level can be selected to change the amount of heating in addition to or in place of selecting the wavelength. In one illustrative example, using a selected wavelength, and increasing the amplitude, a better representation of trapped moisture depth can be identified in porous material 104. By knowing the penetration depth from the selected wavelength and thermal dissipation, the trapped moisture depth can be determined. In other words, the depth at which moisture is present in porous material 104 can be determined. Further, the illustrative example can be applied to materials with voids or channels in which moisture is trapped but cannot escape.

0062With reference to <figref idref="f0003"><b>Figure 3</b></figref><b>,</b> an illustration of a moisture detection system is depicted in accordance with an illustrative example. In the illustrative example, moisture detection system <b>300</b> is an example of one implementation for moisture detection system <b>102</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref><b>.</b>

0063As depicted, moisture detection system <b>300</b> includes radio frequency generator <b>302,</b> magnetron <b>304,</b> waveguide <b>306,</b> and lens antenna <b>308.</b> These components form microwave transmitter <b>309</b> and are examples of components that may be used in electromagnetic radiation system <b>110</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref><b>.</b>

0064As depicted, radio frequency generator <b>302</b> generates a radio frequency for the transmission of microwave beam <b>310.</b> Magnetron <b>304</b> generates electromagnetic radiation in the form of microwaves in the social example. Waveguide <b>306</b> guides the microwaves generated by magnetron <b>304</b> through lens antenna <b>308.</b> Lens antenna <b>308</b> causes the microwaves to be transmitted in of microwave beam <b>310.</b> In the illustrative example, microwave beam <b>310</b> is directed at area <b>312</b> on porous material <b>314.</b>

0065Moisture detection system <b>300</b> also includes infrared camera <b>316</b> and infrared camera triggering unit <b>318.</b> These two components are examples of components that may be used to implement infrared detector system <b>112</b> shown in block form in <figref idref="f0001"><b>Figure</b> 1</figref> or infrared detector system <b>212</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> As depicted, infrared camera <b>316</b> is positioned to detect infrared radiation <b>320</b> from area <b>312</b> in response to heating of porous material <b>314</b> by microwave beam <b>310.</b>

0066As depicted, synchronization circuit <b>322</b> controls the operation of radio frequency generator <b>302</b> and infrared camera triggering unit <b>318.</b> In this manner, synchronization circuit <b>322</b> can cause infrared camera <b>316</b> to detect infrared radiation <b>320</b> in the timing window based on when microwave beam <b>310</b> heats porous material <b>314.</b>

0067In this illustrative example, processor <b>324</b> is configured to receive images <b>326</b> from infrared camera <b>316.</b> Based on images <b>326</b> received, processor <b>324</b> generates moisture indicator <b>328.</b> Moisture indicator <b>328</b> may be an indication of moisture that is present. In other illustrative examples, moisture indicator <b>328</b> may be a visualization such as visualization <b>134</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref> or visualization <b>238</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b>

0068As depicted in this example, processor <b>324</b> in moisture detection system <b>300</b> controls synchronization circuit <b>322</b> to select a timing window to synchronize the operation of transmitting microwave beam <b>310</b> with the detection of infrared radiation by infrared camera <b>316.</b> Processor <b>324</b> is an example of a component that can be used to implement controller <b>114</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref> or controller <b>214</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b>

0069With reference next to <figref idref="f0004"><b>Figure 4</b></figref><b>,</b> an illustration of a phased array is depicted in accordance with an illustrative example. In the depicted example, phased array <b>400</b> is an example of one implementation for phased array <b>210</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> Phased array <b>400</b> can be used in place of microwave transmitter <b>309</b> in <figref idref="f0003"><b>Figure 3</b></figref><b>.</b>

0070In the illustrative example, phased array <b>400</b> includes transmitters <b>402,</b> phase shifters <b>404,</b> and antenna elements <b>406.</b> Phase shifters <b>404</b> can be controlled by a controller such as controller <b>114</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref><b>,</b> controller <b>214</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>,</b> or processor <b>324</b> in <figref idref="f0003"><b>Figure 3</b></figref><b>.</b> As depicted, phase shifters <b>404</b> can be controlled to cause antenna elements <b>406</b> to emit microwave beam <b>408</b> in a direction that can be changed electronically. In other words, microwave beam <b>408</b> is electronically steerable. In this manner, mechanical or moving parts are necessary to direct microwave beam <b>408.</b>

0071The illustration of moisture detection system <b>300</b> in <figref idref="f0003"><b>Figure 3</b></figref> and phased array in <figref idref="f0004"><b>Figure 4</b></figref> are provided as examples of some implementations for components in moisture detection environment <b>100</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref> and moisture detection environment <b>200</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> These examples are not meant to limit the manner in which other illustrative examples may be implemented. For example, although eight transmitters are shown for transmitters <b>402,</b> other numbers of transmitters may be used. For example, 11, 27, 45, or some other suitable number of transmitters may be used in other illustrative examples.

0072Turning next to <figref idref="f0005"><b>Figure 5</b></figref><b>,</b> an illustration of a timing diagram is depicted in accordance with an illustrative example. Timing diagram <b>500</b> includes infrared camera frames graph <b>502,</b> pulse graph <b>504,</b> image storage graph <b>506,</b> and steering graph <b>507.</b>

0073Infrared camera frames graph <b>502</b> is a graph showing the timing of frames during which infrared radiation is detected by an infrared camera. Each frame represents a period of time during which photons are detected for generating an image of infrared radiation in this illustrative example.

0074Pulse graph <b>504</b> is a graph showing the timing of when electromagnetic radiation pulse is emitted by the electromagnetic radiation system and the duration during the pulse of the electromagnetic radiation beam. The depth at which the electromagnetic radiation pulse can be selected based on the frequency. Increasing the frequency increases the penetration, while decreasing the frequency reduces the penetration of the pulse of the electromagnetic radiation beam into the porous material.

0075Image storage graph <b>506</b> is a graph showing the time during which the frames generated by infrared camera are stored. When data is stored, the sensors in the infrared camera are not detecting photons.

0076Steering graph <b>507</b> is a graph showing the steering of the electromagnetic radiation pulse. In this example, steering signal <b>509</b> shows the pulse of electromagnetic radiation being steered from about 0° to about 45° to cover an area of interest.

0077As depicted, two time windows are present, time window <b>508</b> and time window <b>510.</b> In this illustrative example, time window <b>508</b> is a period of time during which frame <b>512</b> is generated and stored. Time window <b>508</b> is used to identify background infrared radiation. This background infrared radiation may reflect the ambient temperature of the environment in which the porous material is located. Time window <b>510</b> is a period of time during which frame <b>514</b> and frame <b>516</b> are detected by the infrared camera.

0078Synchronization is performed such that these frames occur when pulse <b>518</b> in pulse graph <b>504</b> occurs. Pulse <b>518</b> represents the pulse of electromagnetic radiation, such as microwaves, that are directed into the porous material.

0079The timing of pulse <b>518</b> is such that frame <b>514</b> and frame <b>516</b> detect as much infrared radiation as possible. During time window <b>510,</b> the infrared radiation increases from when pulse <b>518</b> begins at time T1 and ends at time T2. The selection of time window <b>510</b> along with the transmission of pulse <b>518</b> within time window <b>510</b> allows for an infrared camera to detect the maximum amount of infrared radiation caused by pulse <b>518,</b> thus increasing the sensitivity of the infrared camera. In this manner, the sensitivity of the infrared camera may be increased through the selection of time window <b>510</b> to include as much of pulse <b>518</b> as possible.

0080Further, the length of pulse <b>518</b> and the size of time window <b>510</b> is selected to cover the time during which photons are detected by the infrared camera prior to transferring signals from the sensors in the infrared camera for storage as an image. As a result, continued transmission of microwaves does not occur while data is read from the sensors in the infrared camera.

0081With reference to <figref idref="f0006"><b>Figure 6</b></figref><b>,</b> an illustration of a table of material parameters is depicted in accordance with an illustrative example. Table <b>600</b> illustrates parameters used in selecting a desired depth of penetration for electromagnetic radiation. In the illustrative example, entry <b>602</b> is for an example porous material, such as a core in a composite sandwich panel. The panel has a decorative laminate that is about 2 mm thick, a skin panel that is about 1 mm thick, and a honeycomb and foam core that is about 25 mm thick.

0082Column <b>604</b> indicates electrical conductivity, column <b>606</b> is magnetic permeability, column <b>608</b> is frequency, and column <b>610</b> identifies depth of penetration. The depth in column <b>610</b> is calculated as follows: <maths id="math0001" num=""><math display="inline"><mrow><mi>δ</mi><mo>≈</mo><mfrac><mn>1</mn><mi mathvariant="italic">√πfµσ</mi></mfrac></mrow></math><img file="EP3474005A2_D0001.tif" /></maths> where <i>δ</i> is standard depth of penetration (mm); <i>π</i> is 3.14; <i>f</i> is test frequency (Hz); <i>µ</i> is magnetic permeability (H/mm); and <i>σ</i> is electrical conductivity (%IACS).

0083In this depicted example, table <b>600</b> provides a depth of penetration for the core in this example. Generally, the depth of penetration increases as the frequency increases. All of the properties of the porous material being inspected can be taken into account in determining the depth of penetration. For example, when the porous material is a composite sandwich core, the decorative laminate, the panel skin, as well as the honeycomb and foam core may also be taken into account to obtain a more accurate depth of penetration.

0084Turning next to <figref idref="f0006"><b>Figure 7</b></figref><b>,</b> an illustration of a flowchart of a process for detecting moisture in a porous material is depicted in accordance with an illustrative example. The process illustrated in <figref idref="f0006"><b>Figure 7</b></figref> can be implemented in moisture detection system <b>102</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref><b>.</b> This process may be implemented in at least one of hardware or software. When software in the form of program code is used, the program code can be run by a processor unit to perform the different operations.

0085The process begins by transmitting electromagnetic radiation into a porous material (operation <b>700</b>). The electromagnetic radiation beam in operation <b>700</b> has a number of wavelengths that is absorbed by water molecules. In this example, selecting the number of frequencies for the electromagnetic radiation is based on a desired depth at which a pulse of electromagnetic radiation penetrates the composite sandwich panel.

0086The process detects an amount of infrared radiation in the porous material of a panel in response to transmitting the electromagnetic radiation into a composite sandwich panel using a time window selected to detect the amount of infrared radiation when the electromagnetic radiation heats the porous material (operation <b>702</b>). The process identifies a level of moisture in the porous material using an amount of energy in the electromagnetic radiation transmitted and the amount of infrared radiation detected (operation <b>704</b>). The process terminated thereafter.

0087With reference next to <figref idref="f0007"><b>Figure 8</b></figref><b>,</b> an illustration of a flowchart of a process for detecting moisture in a composite sandwich panel for an aerospace vehicle is depicted in accordance with an illustrative example. This process may be implemented in at least one of hardware or software. When software in the form of program code is used, the program code can be run by a processor unit to perform the different operations in the process.

0088The process begins by transmitting a pulse of electromagnetic radiation into a composite sandwich panel such that the composite sandwich panel is heated above an ambient temperature (operation <b>800</b>). The process detects an amount of infrared radiation generated in the composite sandwich panel in response to transmitting the pulse of electromagnetic radiation into the composite sandwich panel using a time window selected to detect the amount of infrared radiation when the pulse of electromagnetic radiation heats the composite sandwich panel (operation <b>802).</b> The amount of infrared radiation detected indicates an amount of moisture in the composite sandwich panel.

0089The process determines the level of moisture in the composite sandwich panel using the amount of infrared radiation detected and the energy in the pulse of electromagnetic radiation sent into the composite sandwich panel (operation <b>804</b>). The process then generates a visualization of the level of moisture (operation <b>806</b>). The process terminates thereafter.

0090The visualization may be selected from at least one of a thermal image, a thermal map, or some other representation. This visualization may be used to identify locations where moisture is present. Further, the visualization may indicate the depth at which the moisture is present in those locations.

0091Based on the level of moisture detected, an action can be performed with respect to the composite sandwich panel. This action can be selected from reworking or replacing the composite sandwich panel. The reworking may include, for example, sending additional electromagnetic radiation into the composite sandwich panel in an effort to reduce the moisture in the composite sandwich panel. Other moisture reduction techniques also may be used. Thermal or infrared heating may be employed.

0092Turning next to <figref idref="f0007"><b>Figure 9</b></figref><b>,</b> an illustration of a flowchart of a process for detecting moisture in a porous material is depicted in accordance with an illustrative example. The process illustrated in <figref idref="f0007"><b>Figure 9</b></figref> can be implemented in moisture detection system <b>202</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> This process may be implemented in at least one of hardware or software. When software in the form of program code is used, the program code can be run by a processor unit to perform the different operations.

0093The process beings by beam steering a pulse of an electromagnetic radiation beam in an area on a porous material (operation <b>900</b>). The beam steering moves the pulse of the electromagnetic radiation beam across the area to cover the area. The pulse of the electromagnetic radiation beam has a number of wavelengths that are absorbed by water molecules.

0094The process synchronizes the timing of the pulse of the electromagnetic radiation beam to heat the porous material in the area with a time window in an infrared detector system to detect an amount of infrared radiation from the area (operation <b>902</b>). The process detects the amount of infrared radiation in area on the porous material within the time window for the infrared detector system when the area on the porous material is heated by the pulse of the electromagnetic radiation beam (operation <b>904</b>). The process terminates thereafter. The amount of infrared radiation indicates a level of moisture in the porous material.

0095With reference to <figref idref="f0008"><b>Figure 10</b></figref><b>,</b> an illustration of a flowchart of a process for detecting moisture in a composite sandwich panel for an aerospace vehicle is depicted in accordance with an illustrative example. The process illustrated in <figref idref="f0008"><b>Figure 10</b></figref> can be implemented in moisture detection system <b>202</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> This process may be implemented in at least one of hardware or software. When software in the form of program code is used, the program code can be run by a processor unit to perform the different operations.

0096The process begins by selecting an area on a composite sandwich panel (operation <b>1000</b>). This area can be some of or all of the composite sandwich panel. The process selects a number of frequencies for a pulse of an electromagnetic radiation beam based on a desired depth at which the pulse of the electromagnetic radiation penetrates the composite sandwich panel (operation <b>1002</b>). The pulse of the electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules.

0097The process beam steers the pulse of the electromagnetic radiation beam to the area on the composite sandwich panel (operation <b>1004</b>). The steering can be performed such that the entire area is covered during a pulse or multiple pulses may be used to cover the area. The process synchronizes timing of the pulse of the electromagnetic radiation beam to heat the composite sandwich panel with a time window in the infrared detector system to detect an amount of infrared radiation (operation <b>1006</b>).

0098The process detects the amount of infrared radiation in the composite sandwich panel in the area within the time window for the infrared detector system when the composite sandwich panel is heated by the pulse of the electromagnetic radiation beam (operation <b>1008</b>). The amount of infrared radiation indicates a level of moisture in the composite sandwich panel.

0099The process determines the level of moisture in the area on the composite sandwich panel using the amount of infrared radiation detected in the area and energy in the pulse of the electromagnetic radiation beam sent into the area on the composite sandwich panel (operation <b>1010</b>).

0100A determination is made as to whether another area is present for inspection on the composite sandwich panel (operation <b>1012</b>). If another area is present, the process returns to operation <b>1000.</b> Otherwise, the process generates a visualization of the moisture (operation <b>1014</b>). The process terminates thereafter.

0101The visualization can be a thermal image or a map of the infrared radiation for the porous material using the energy in the pulse of the electromagnetic radiation beam and the amount of infrared radiation detected by the infrared detector system in the area within the time window.

0102With reference to <figref idref="f0009"><b>Figure 11</b></figref><b>,</b> an illustration of a flowchart of a process for managing actions performed with respect to a porous material in response to detecting a level of moisture is depicted in accordance with an illustrative example. The process illustrated in <figref idref="f0008"><b>Figure 10</b></figref> can be implemented in moisture detection system <b>202</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> This process may be implemented in at least one of hardware or software. When software in the form of program code is used, the program code can be run by a processor unit to perform the different operations.

0103The process begins by receiving a number of thermal images for a porous material (operation <b>1100</b>). In this illustrative example, the number of thermal images may be for one or more areas of interest in the porous material. The process determines a level of moisture using the number of thermal images (operation <b>1102</b>).

0104The process determines whether the porous material should be reworked or replaced using a map (operation <b>1104</b>). If the porous material should be replaced, the process generates a message to replace the porous material (operation <b>1106</b>). The process terminates thereafter.

0105With reference again to operation <b>1104,</b> if a determination is made that the porous material should be reworked, the process identifies the extent of rework needed (operation <b>1108</b>). This extent can be graphically identified on the map or with other instructions.

0106Further, the extent of rework also may identify the operations that should be performed to rework the porous material. This rework can include heating or other actions. For example, the rework may include removing a skin panel or decorative laminate from a composite sandwich panel, heating the composite sandwich panel, and then replacing the skin panel or decorative.

0107The process then generates a message identifying the extent of rework to be performed (operation <b>1110</b>). The process terminates thereafter.

0108The flowcharts and block diagrams in the different depicted examples illustrate the architecture, functionality, and operation of some possible implementations of apparatuses and methods in an illustrative example. In this regard, each block in the flowcharts or block diagrams may represent at least one of a module, a segment, a function, or a portion of an operation or step. For example, one or more of the blocks may be implemented as program code, hardware, or a combination of the program code and hardware. When implemented in hardware, the hardware may, for example, take the form of integrated circuits that are manufactured or configured to perform one or more operations in the flowcharts or block diagrams. When implemented as a combination of program code and hardware, the implementation may take the form of firmware. Each block in the flowcharts or the block diagrams may be implemented using special purpose hardware systems that perform the different operations or combinations of special purpose hardware and program code run by the special purpose hardware.

0109In some alternative implementations of an illustrative example, the function or functions noted in the blocks may occur out of the order noted in the figures. For example, in some cases, two blocks shown in succession may be performed substantially concurrently, or the blocks may sometimes be performed in the reverse order, depending upon the functionality involved. Also, other blocks may be added in addition to the illustrated blocks in a flowchart or block diagram.

0110Turning now to <figref idref="f0010"><b>Figure 12</b></figref><b>,</b> an illustration of a block diagram of a data processing system is depicted in accordance with an illustrative example. Data processing system <b>1200</b> may be used to implement computer system <b>144</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref> and computer system <b>215</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> In this illustrative example, data processing system <b>1200</b> includes communications framework <b>1202,</b> which provides communications between processor unit <b>1204,</b> memory <b>1206,</b> persistent storage <b>1208,</b> communications unit <b>1210,</b> input/output (I/O) unit <b>1212,</b> and display <b>1214.</b> In this example, communications framework <b>1202</b> may take the form of a bus system.

0111Processor unit <b>1204</b> serves to execute instructions for software that may be loaded into memory <b>1206.</b> Processor unit <b>1204</b> may be a number of processors, a multi-processor core, or some other type of processor, depending on the particular implementation.

0112Memory <b>1206</b> and persistent storage <b>1208</b> are examples of storage devices <b>1216.</b> A storage device is any piece of hardware that is capable of storing information, such as, for example, without limitation, at least one of data, program code in functional form, or other suitable information either on a temporary basis, a permanent basis, or both on a temporary basis and a permanent basis. Storage devices <b>1216</b> may also be referred to as computer-readable storage devices in these illustrative examples. Memory <b>1206,</b> in these examples, may be, for example, a random-access memory or any other suitable volatile or non-volatile storage device. Persistent storage <b>1208</b> may take various forms, depending on the particular implementation.

0113For example, persistent storage <b>1208</b> may contain one or more components or devices. For example, persistent storage <b>1208</b> may be a hard drive, a solid state hard drive, a flash memory, a rewritable optical disk, a rewritable magnetic tape, or some combination of the above. The media used by persistent storage <b>1208</b> also may be removable. For example, a removable hard drive may be used for persistent storage <b>1208.</b>

0114Communications unit <b>1210,</b> in these illustrative examples, provides for communications with other data processing systems or devices. In these illustrative examples, communications unit <b>1210</b> is a network interface card.

0115Input/output unit <b>1212</b> allows for input and output of data with other devices that may be connected to data processing system <b>1200.</b> For example, input/output unit <b>1212</b> may provide a connection for user input through at least one of a keyboard, a mouse, or some other suitable input device. Further, input/output unit <b>1212</b> may send output to a printer. Display <b>1214</b> provides a mechanism to display information to a user.

0116Instructions for at least one of the operating system, applications, or programs may be located in storage devices <b>1216,</b> which are in communication with processor unit <b>1204</b> through communications framework <b>1202.</b> The processes of the different examples may be performed by processor unit <b>1204</b> using computer-implemented instructions, which may be located in a memory, such as memory <b>1206.</b>

0117These instructions are referred to as program code, computer usable program code, or computer-readable program code that may be read and executed by a processor in processor unit <b>1204.</b> The program code in the different examples may be embodied on different physical or computer-readable storage media, such as memory <b>1206</b> or persistent storage <b>1208.</b>

0118Program code <b>1218</b> is located in a functional form on computer-readable media <b>1220</b> that is selectively removable and may be loaded onto or transferred to data processing system <b>1200</b> for execution by processor unit <b>1204.</b> Program code <b>1218</b> and computer-readable media <b>1220</b> form computer program product <b>1222</b> in these illustrative examples. In one example, computer-readable media <b>1220</b> may be computer-readable storage media <b>1224</b> or computer-readable signal media <b>1226.</b>

0119In these illustrative examples, computer-readable storage media <b>1224</b> is a physical or tangible storage device used to store program code <b>1218</b> rather than a medium that propagates or transmits program code <b>1218.</b>

0120Alternatively, program code <b>1218</b> may be transferred to data processing system <b>1200</b> using computer-readable signal media <b>1226.</b> Computer-readable signal media <b>1226</b> may be, for example, a propagated data signal containing program code <b>1218.</b> For example, computer-readable signal media <b>1226</b> may be at least one of an electromagnetic signal, an optical signal, or any other suitable type of signal. These signals may be transmitted over at least one of communications links, such as wireless communications links, optical fiber cable, coaxial cable, a wire, or any other suitable type of communications link.

0121The different components illustrated for data processing system <b>1200</b> are not meant to provide architectural limitations to the manner in which different examples may be implemented. The different illustrative examples may be implemented in a data processing system including components in addition to or in place of those illustrated for data processing system <b>1200.</b> Other components shown in <figref idref="f0010"><b>Figure 12</b></figref> can be varied from the illustrative examples shown. The different examples may be implemented using any hardware device or system capable of running program code <b>1218.</b>

0122Illustrative examples of the disclosure may be described in the context of aircraft manufacturing and service method <b>1300</b> as shown in <figref idref="f0011"><b>Figure 13</b></figref> and aircraft <b>1400</b> as shown in <figref idref="f0011"><b>Figure 14</b></figref><b>.</b> Turning first to <figref idref="f0011"><b>Figure 13</b></figref><b>,</b> an illustration of a block diagram of an aircraft manufacturing and service method is depicted in accordance with an illustrative example. During pre-production, aircraft manufacturing and service method <b>1300</b> may include specification and design <b>1302</b> of aircraft <b>1400</b> in <figref idref="f0011"><b>Figure 14</b></figref> and material procurement <b>1304.</b>

0123During production, component and subassembly manufacturing <b>1306</b> and system integration <b>1308</b> of aircraft <b>1400</b> takes place. Thereafter, aircraft <b>1400</b> may go through certification and delivery <b>1310</b> in order to be placed in service <b>1312.</b> While in service <b>1312</b> by a customer, aircraft <b>1400</b> is scheduled for routine maintenance and service <b>1314,</b> which may include modification, reconfiguration, refurbishment, and other maintenance or service.

0124Each of the processes of aircraft manufacturing and service method <b>1300</b> may be performed or carried out by a system integrator, a third party, an operator, or some combination thereof. In these examples, the operator may be a customer. For the purposes of this description, a system integrator may include, without limitation, any number of aircraft manufacturers and major-system subcontractors; a third party may include, without limitation, any number of vendors, subcontractors, and suppliers; and an operator may be an airline, a leasing company, a military entity, a service organization, and so on.

0125With reference now to <figref idref="f0011"><b>Figure 14</b></figref><b>,</b> an illustration of a block diagram of an aircraft is depicted in which an illustrative example may be implemented. In this example, aircraft <b>1400</b> is produced by aircraft manufacturing and service method <b>1300</b> in <figref idref="f0011"><b>Figure 13</b></figref> and may include airframe <b>1402</b> with plurality of systems <b>1404</b> and interior <b>1406.</b> Examples of systems <b>1404</b> include one or more of propulsion system <b>1408,</b> electrical system <b>1410,</b> hydraulic system <b>1412,</b> and environmental system <b>1414.</b> Any number of other systems may be included. Although an aerospace example is shown, different illustrative examples may be applied to other industries, such as the automotive industry.

0126Apparatuses and methods embodied herein may be employed during at least one of the stages of aircraft manufacturing and service method <b>1300</b> in <figref idref="f0011"><b>Figure 13</b></figref><b>.</b>

0127In one illustrative example, components or subassemblies produced in component and subassembly manufacturing <b>1306</b> in <figref idref="f0011"><b>Figure 13</b></figref> may be fabricated or manufactured in a manner similar to components or subassemblies produced while aircraft <b>1400</b> is in service <b>1312</b> in <figref idref="f0011"><b>Figure 13</b></figref><b>.</b> Moisture detection system <b>102</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref> and moisture detection system <b>202</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref> may be utilized to inspect porous materials for components or subassemblies produced during component and subassembly manufacturing <b>1306</b> or while aircraft is in service <b>1312.</b>

0128As yet another example, one or more apparatus examples, method examples, or a combination thereof may be utilized during production stages, such as component and subassembly manufacturing <b>1306</b> and system integration <b>1308</b> in <figref idref="f0011"><b>Figure 13</b></figref><b>.</b> Moisture detection system <b>102</b> in <figref idref="f0001">figure 1</figref> and moisture detection system <b>202</b> in <figref idref="f0002">figure 2</figref> may be utilized to inspect porous materials for components or subassemblies during component and subassembly manufacturing <b>1306,</b> system integration <b>1308,</b> and certification and delivery <b>1310.</b> These inspections may be performed prior to delivery of aircraft <b>1400</b> to a customer. In other illustrative examples, these inspections may be performed during maintenance and service <b>1314.</b>

0129One or more apparatus examples, method examples, or a combination thereof may be utilized while aircraft <b>1400</b> is in service <b>1312,</b> during maintenance and service <b>1314</b> in <figref idref="f0011"><b>Figure 13</b></figref><b>,</b> or both. The use of a number of the different illustrative examples may substantially expedite the assembly of aircraft <b>1400,</b> reduce the cost of aircraft <b>1400,</b> or both expedite the assembly of aircraft <b>1400</b> and reduce the cost of aircraft <b>1400.</b>

0130Turning now to <figref idref="f0011"><b>Figure 15</b></figref><b>,</b> an illustration of a block diagram of a product management system is depicted in accordance with an illustrative example. Product management system <b>1500</b> is a physical hardware system. In this illustrative example, product management system <b>1500</b> may include at least one of manufacturing system <b>1502</b> or maintenance system <b>1504.</b>

0131Manufacturing system <b>1502</b> is configured to manufacture products, such as aircraft <b>1400</b> in <figref idref="f0011"><b>Figure 14</b></figref><b>.</b> As depicted, manufacturing system <b>1502</b> includes manufacturing equipment <b>1506.</b> Manufacturing equipment <b>1506</b> includes at least one of fabrication equipment <b>1508</b> or assembly equipment <b>1510.</b> Manufacturing equipment <b>1506</b> also may include moisture detection system <b>102</b> in <figref idref="f0001"><b>Figure 1</b></figref> and moisture detection system <b>202</b> in <figref idref="f0002"><b>Figure 2</b></figref> for use in inspecting components manufactured by manufacturing equipment <b>1506</b>

0132Fabrication equipment <b>1508</b> is equipment that may be used to fabricate components for parts used to form aircraft <b>1400.</b> For example, fabrication equipment <b>1508</b> may include machines and tools. These machines and tools may be at least one of a drill, a hydraulic press, a furnace, a mold, a composite tape laying machine, a vacuum system, a lathe, or other suitable types of equipment. Fabrication equipment <b>1508</b> may be used to fabricate at least one of metal parts, composite parts, semiconductors, circuits, fasteners, ribs, skin panels, spars, antennas, or other suitable types of parts.

0133Assembly equipment <b>1510</b> is equipment used to assemble parts to form aircraft <b>1400.</b> In particular, assembly equipment <b>1510</b> may be used to assemble components and parts to form aircraft <b>1400.</b> Assembly equipment <b>1510</b> also may include machines and tools. These machines and tools may be at least one of a robotic arm, a crawler, a faster installation system, a rail-based drilling system, or a robot. Assembly equipment <b>1510</b> may be used to assemble parts such as seats, horizontal stabilizers, wings, engines, engine housings, landing gear systems, and other parts for aircraft <b>1400.</b>

0134In this illustrative example, maintenance system <b>1504</b> includes maintenance equipment <b>1512.</b> Maintenance equipment <b>1512</b> may include any equipment needed to perform maintenance on aircraft <b>1400.</b> Maintenance equipment <b>1512</b> may include tools for performing different operations on parts on aircraft <b>1400.</b> These operations may include at least one of disassembling parts, refurbishing parts, inspecting parts, reworking parts, manufacturing replacement parts, or other operations for performing maintenance on aircraft <b>1400.</b> These operations may be for routine maintenance, inspections, upgrades, refurbishment, or other types of maintenance operations.

0135In the illustrative example, maintenance equipment <b>1512</b> may include ultrasonic inspection devices, x-ray imaging systems, vision systems, drills, crawlers, and other suitable device. For example, maintenance equipment <b>1512</b> also may include moisture detection system <b>102</b> shown in block form in <figref idref="f0001"><b>Figure 1</b></figref> and moisture detection system <b>202</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref> for use in inspecting porous materials such as a composite sandwich panel or other types of suitable components. In some cases, maintenance equipment <b>1512</b> may include fabrication equipment <b>1508,</b> assembly equipment <b>1510,</b> or both to produce and assemble parts that may be needed for maintenance.

0136Product management system <b>1500</b> also includes control system <b>1514.</b> Control system <b>1514</b> is a hardware system and may also include software or other types of components. Control system <b>1514</b> is configured to control the operation of at least one of manufacturing system <b>1502</b> or maintenance system <b>1504.</b> In particular, control system <b>1514</b> may control the operation of at least one of fabrication equipment <b>1508,</b> assembly equipment <b>1510,</b> or maintenance equipment <b>1512.</b>

0137The hardware in control system <b>1514</b> may be using hardware that may include computers, circuits, networks, and other types of equipment. The control may take the form of direct control of manufacturing equipment <b>1506.</b> For example, robots, computer-controlled machines, and other equipment may be controlled by control system <b>1514.</b> In other illustrative examples, control system <b>1514</b> may manage operations performed by human operators <b>1516</b> in manufacturing or performing maintenance on aircraft <b>1400</b> in <figref idref="f0011"><b>Figure 14</b></figref><b>.</b> For example, control system <b>1514</b> may assign tasks, provide instructions, display models, or perform other operations to manage operations performed by human operators <b>1516.</b> In these illustrative examples, may be implemented in control system <b>1514</b> to manage at least one of the manufacturing or maintenance of aircraft <b>1400.</b>

0138For example, management may include inspections performed using moisture detection system <b>102</b> shown in block form in <figref idref="f0001"><b>Figure</b> 1</figref> and moisture detection system <b>202</b> shown in block form in <figref idref="f0002"><b>Figure 2</b></figref><b>.</b> Based on the level of moisture detected, control system <b>1514</b> may perform actions such as initiating rework, replacement, or other actions with respect to the inspected components. Further, the moisture detection system may generate a map of moisture from the infrared radiation detected within a structure such as a composite sandwich panel. The amount of infrared radiation in a thermal image correlates to the amount of moisture present in the structure.

0139This map may be used to determine whether rework or replacement of a component should occur. Further, when rework occurs, the map may also be used to determine whether rework should be performed. This determination may be turned into instructions that are used to control other equipment or sent to human operator <b>1516.</b>

0140In the different illustrative examples, human operators <b>1516</b> may operate or interact with at least one of manufacturing equipment <b>1506,</b> maintenance equipment <b>1512,</b> or control system <b>1514.</b> This interaction may be performed to manufacture aircraft <b>1400.</b>

0141Of course, product management system <b>1500</b> may be configured to manage other products other than aircraft <b>1400.</b> Although product management system <b>1500</b> has been described with respect to manufacturing in the aerospace industry, product management system <b>1500</b> may be configured to manage products for other industries. For example, product management system <b>1500</b> can be configured to manufacture products for the automotive industry as well as any other suitable industries.

0142Further, the disclosure comprises examples according to the following clauses: <ul id="ul0002" list-style="none" compact="compact"><li>Clause 1. A moisture detection system comprising: an electromagnetic radiation system; an infrared detector system; and a controller in communication with the electromagnetic radiation system and the infrared detector system, wherein the controller is configured to control the electromagnetic radiation system to transmit a pulse of electromagnetic radiation in which the pulse of electromagnetic radiation has a number of wavelengths that is absorbed by water molecules; and control the infrared detector system to detect an amount of infrared radiation in response to transmitting the pulse of electromagnetic radiation using a time window, wherein the amount of infrared radiation indicates a level of moisture.</li><li>Clause 2. The moisture detection system of Clause 1, wherein the controller is configured to control the electromagnetic radiation system to transmit a pulse of electromagnetic radiation into a composite sandwich panel; control the infrared detector system to detect an amount of infrared radiation in response to transmitting the pulse of electromagnetic radiation into the composite sandwich panel using the time window selected to detect the amount of infrared radiation when the pulse of electromagnetic radiation heats the composite sandwich panel such that the infrared detector system detects the amount of infrared radiation in the composite sandwich panel when the composite sandwich panel is heated by the pulse of electromagnetic radiation, wherein the amount of infrared radiation indicates the level of moisture in the composite sandwich panel.</li><li>Clause 3. The moisture detection system of Clause 2, wherein the controller is configured to control the infrared detector system to detect an amount of background infrared radiation prior to the electromagnetic radiation system transmitting the pulse of electromagnetic radiation.</li><li>Clause 4. The moisture detection system of Clause 3, wherein the controller is configured to determine the level of moisture in the composite sandwich panel using the amount of infrared radiation detected and energy in the pulse of electromagnetic radiation sent into the composite sandwich panel.</li><li>Clause 5. The moisture detection system of Clause 2 or 3, wherein the time window is selected to detect the amount of infrared radiation in response to the pulse of electromagnetic radiation heating the composite sandwich panel such that a sensitivity of the infrared detector system is increased.</li><li>Clause 6. The moisture detection system of any one of Clauses 2-5, wherein the controller is configured to select a number of frequencies for the pulse of electromagnetic radiation based on a desired depth at which the pulse of electromagnetic radiation penetrates the composite sandwich panel.</li><li>Clause 7. The moisture detection system of any one of Clauses 2-6, wherein the controller is configured to generate at least one of a thermal map or a thermal image of infrared radiation for the composite sandwich panel using the amount of infrared radiation detected by the infrared detector system within the time window.</li><li>Clause 8. The moisture detection system of any one of Clauses 2-7, wherein the controller is configured to control the electromagnetic radiation system to transmit the pulse of electromagnetic radiation through a lens antenna to form an electromagnetic radiation beam directed at the composite sandwich panel such that the composite sandwich panel is heated above an ambient temperature for the composite sandwich panel.</li><li>Clause 9. The moisture detection system of any one of Clauses 2-8, wherein the pulse of electromagnetic radiation has a number of frequencies selected from about 300 MHz to about 300 GHz.</li><li>Clause 10. The moisture detection system of any one of Clauses 2-9, wherein the composite sandwich panel comprises a first face sheet, a second face sheet, and a core located between the first face sheet and the second face sheet, wherein the core is selected from at least one of a foam core, an open cell foam core, a closed cell foam core, or a honeycomb core.</li><li>Clause 11. The moisture detection system of any one of Clauses 2-10, wherein the composite sandwich panel is for an aerospace vehicle, which is selected from one of an airplane, an aircraft, a commercial airplane, a rotorcraft, a spacecraft, a commercial spacecraft, and a space plane.</li><li>Clause 12. A method for detecting moisture in a composite sandwich panel for an aerospace vehicle, the method comprising: transmitting a pulse of electromagnetic radiation into the composite sandwich panel such that the composite sandwich panel is heated above an ambient temperature; and detecting an amount of infrared radiation generated in the composite sandwich panel in response to transmitting the pulse of electromagnetic radiation into the composite sandwich panel using a time window selected to detect the amount of infrared radiation when the pulse of electromagnetic radiation heats the composite sandwich panel, wherein the amount of infrared radiation detected indicates a level of moisture in the composite sandwich panel.</li><li>Clause 13. The method of Clause 12 further comprising: determining the level of moisture in the composite sandwich panel using the amount of infrared radiation detected and energy in the pulse of electromagnetic radiation sent into the composite sandwich panel.</li><li>Clause 14. The method of Clause 12 or 13 further comprising: selecting the time window to detect the amount of infrared radiation when the pulse of electromagnetic radiation heats the composite sandwich panel above the ambient temperature such that a sensitivity of an infrared detector system is increased.</li><li>Clause 15. The method of any one of Clauses 12-14 further comprising: selecting a number of frequencies for the pulse of electromagnetic radiation based on a desired depth at which the pulse of electromagnetic radiation penetrates the composite sandwich panel.</li><li>Clause 16. The method of any one of Clauses 12-15 further comprising: generating a thermal image of the amount of infrared radiation for the composite sandwich panel using the amount of infrared radiation detected in the time window.</li><li>Clause 17. The method of any one of Clauses 12-16, wherein performing an action with respect to the composite sandwich panel comprises: transmitting additional electromagnetic radiation into the composite sandwich panel such that the level of moisture inside of the composite sandwich panel is reduced.</li><li>Clause 18. The method of any one of Clauses 12-17, wherein an action is selected from one of reworking the composite sandwich panel and replacing the composite sandwich panel.</li><li>Clause 19. The method of any one of Clauses 12-18, wherein transmitting the pulse of electromagnetic radiation into the composite sandwich panel such that the composite sandwich panel comprises: transmitting the pulse of electromagnetic radiation through a lens antenna to form a pulse of electromagnetic radiation beam directed at the composite sandwich panel such that the composite sandwich panel is heated above the ambient temperature for the composite sandwich panel.</li><li>Clause 20. The method of any one of Clauses 12-19, wherein transmitting and detecting steps are performed while the composite sandwich panel is installed in the aerospace vehicle.</li><li>Clause 21. The method of any one of Clauses 12-20, wherein transmitting and detecting steps are performed prior to installation of the composite sandwich panel in the aerospace vehicle.</li><li>Clause 22. The method of any one of Clauses 12-21, wherein the pulse of electromagnetic radiation has a number of frequencies selected from about 300 MHz to about 300 GHz.</li><li>Clause 23. The method of any one of Clauses 12-22, wherein the composite sandwich panel comprises a first face sheet, a second face sheet, and a core located between the first face sheet and the second face sheet, wherein the core is selected from at least one of a foam core, an open cell foam core, a closed cell foam core, or a honeycomb core.</li><li>Clause 24. The method of any one of Clauses 12-23, wherein the aerospace vehicle is selected from one of an airplane, an aircraft, a commercial airplane, a rotorcraft, a spacecraft, a commercial spacecraft, and a space plane.</li><li>Clause 25. A moisture detection system comprising: an electromagnetic radiation system; an infrared detector system configured to detect an amount of infrared radiation; and a controller configured to control the electromagnetic radiation system to transmit a pulse of electromagnetic radiation into a porous material in which a pulse of electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules; control the infrared detector system to detect the amount of infrared radiation in the porous material in response to transmitting the pulse of electromagnetic radiation into the porous material using a time window that captures when the pulse of electromagnetic radiation heats the porous material such that the infrared detector system detects the amount of infrared radiation in the porous material when the porous material is heated by the pulse of electromagnetic radiation; and identify a level of moisture in the porous material using an amount of energy in the pulse of electromagnetic radiation transmitted and the amount of infrared radiation detected.</li><li>Clause 26. The moisture detection system of Clause 25, wherein the controller selects a number of frequencies for the pulse of electromagnetic radiation based on a desired depth at which the pulse of electromagnetic radiation penetrates a composite sandwich panel.</li><li>Clause 27. The moisture detection system of Clause 25 or 26, wherein the porous material is selected from a group comprising a composite panel, a composite sandwich panel, and a monument for an interior of an aerospace vehicle.</li><li>Clause 28. A method for detecting moisture in a porous material, the method comprising: transmitting electromagnetic radiation into the porous material, wherein an electromagnetic radiation beam has a number of wavelengths that is absorbed by water molecules; and detecting an amount of infrared radiation in the porous material in response to transmitting the electromagnetic radiation into a composite sandwich panel using a time window selected to detect the amount of infrared radiation when the electromagnetic radiation heats the porous material; and identifying a level of moisture in the porous material using an amount of energy in the electromagnetic radiation transmitted and the amount of infrared radiation detected.</li><li>Clause 29. The method of Clause 28, wherein the porous material is selected from a group comprising a composite panel, the composite sandwich panel, and a monument for an interior of an aerospace vehicle.</li><li>Clause 30. The method of Clause 28 or 29 further comprising: selecting the time window to detect the amount of infrared radiation when the electromagnetic radiation heats the porous material above an ambient temperature such that a sensitivity of an infrared detector system is increased.</li><li>Clause 31. The method of any one of Clauses 28-30 further comprising: selecting a number of frequencies for a pulse of the electromagnetic radiation based on a desired depth at which the electromagnetic radiation penetrates the composite sandwich panel.</li></ul>

0143The description of the different illustrative examples has been presented for purposes of illustration and description and is not intended to be exhaustive or limited to the examples in the form disclosed. The different illustrative examples describe components that perform actions or operations. In an illustrative example, a component may be configured to perform the action or operation described. For example, the component may have a configuration or design for a structure that provides the component an ability to perform the action or operation that is described in the illustrative examples as being performed by the component.

0144Thus, the illustrative examples provide one or more solutions that overcome a problem with detecting moisture in porous structures such as composite sandwich panels. One or more solutions may provide an ability to detect moisture in a porous material including a composite sandwich panel. A controller controls the operation of an electromagnetic radiation system and an infrared detector system to detect a level of moisture using a time window. The selection of the time window can increase the sensitivity of the infrared detector system.

0145Many modifications and variations will be apparent to those of ordinary skill in the art. Further, different illustrative examples may provide different features as compared to other desirable examples. The example or examples selected are chosen and described in order to best explain the principles of the examples, the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various examples with various modifications as are suited to the particular use contemplated.