Hydrothermal excitation-based epoxy resin defect detection method and system

Abstract

The invention discloses an epoxy resin defect detection method and system based on hydrothermal excitation, and relates to the technical field of epoxy resin defect detection.The epoxy resin defect detection method comprises the steps that hydrothermal excitation is conducted on the surface of epoxy resin; collecting thermal image data of the surface of the epoxy resin after hydrothermal excitation; performing image processing on the thermal image data; and analyzing the processed thermal image, and identifying the defects on the surface of the epoxy resin. According to the epoxy resin defect detection method based on hydrothermal excitation, in the detection process, the infrared thermal imaging technology is used, and the defect is recognized through the change of the internal temperature of the epoxy resin after hydrothermal excitation. The method has the advantages of intuition, rapidness, no need of contact with the surface of a defective sample piece and the like, has higher reliability, and is suitable for online detection. The infrared thermal imaging technology can effectively detect the defects in the epoxy resin, and can accurately determine the positions and sizes of the defects.

Description

Technical Field

[0001] The present invention relates to the technical field of epoxy resin defect detection, and in particular to an epoxy resin defect detection method and system based on hydrothermal excitation. Background Art

[0002] In recent years, sudden accidents such as flashover, breakdown, and explosion of GIS insulators have occurred one after another. According to the analysis of failure statistics, GIS insulator failures are mostly caused by weak insulation defects and aging problems after long-term service. After long-term energized operation, the inherent defects in the insulators gradually expand, eventually leading to breakdown discharge. Therefore, accurately diagnosing the actual insulation status of GIS equipment has become an important basis for evaluating the operation of the equipment.

[0003] The epoxy resin defect detection method based on hydrothermal excitation is a technology that uses hydrothermal conditions to thermally excite epoxy resin materials and detects their internal defects through infrared thermal imaging technology. Epoxy resin is a polymer material widely used in the electrical field, but its performance will be affected to a certain extent in the external environment, so the detection of its defects is particularly important.

[0004] In the detection process, infrared thermal imaging technology is usually used to identify defects by observing the change in temperature inside the epoxy resin after hydrothermal excitation. This method has the advantages of being intuitive, fast, and not requiring contact with the surface of the defective sample. It has high reliability and is suitable for online detection. Infrared thermal imaging technology can effectively detect defects inside epoxy resin and can accurately determine the location and size of the defects.

[0005] Infrared thermal wave excitation nondestructive testing technology is a method of detecting internal defects of materials using infrared thermal imaging technology. This technology detects internal defects of objects by applying thermal excitation on the surface of the object and then using an infrared thermal imager to capture the thermal response of the surface of the object. Although this technology has shown its unique advantages in many fields, it also has some disadvantages and limitations:

[0006] Influence of environmental factors: Infrared thermal wave excitation technology has limited adaptability to the environment. For example, its performance may be affected in high or low temperature environments.

[0007] Limitation of detection depth: Although infrared thermal wave technology can detect defects deeper inside an object, its detection ability is still limited for deeper defects.

[0008] Sensitive to rapidly changing temperature fields: If the temperature field of the object being measured changes rapidly, the accuracy and sensitivity of the infrared thermal imaging equipment may be affected, resulting in inaccurate detection results. Summary of the invention

[0009] In view of the above-mentioned problems, the present invention is proposed.

[0010] Therefore, the technical problem solved by the present invention is that defects on the surface of epoxy resin can be accurately detected by using infrared thermal imaging technology through hydrothermal excitation.

[0011] While infrared thermography is typically used to detect surface or near-surface defects, the ability to detect deeper defects can be improved through hydrothermal excitation.

[0012] To solve the above technical problems, the present invention provides the following technical solutions: a method for detecting epoxy resin defects based on hydrothermal excitation, comprising: performing hydrothermal excitation on the epoxy resin surface; collecting thermal image data of the epoxy resin surface after hydrothermal excitation; performing image processing on the thermal image data; analyzing the processed thermal image to identify defects on the epoxy resin surface.

[0013] As a preferred embodiment of the epoxy resin defect detection method based on hydrothermal excitation of the present invention, before the epoxy resin surface is subjected to hydrothermal excitation, the method further comprises:

[0014] Place the epoxy resin sample in the sample tank of the hydrothermal reactor.

[0015] As a preferred solution of the epoxy resin defect detection method based on hydrothermal excitation described in the present invention, wherein: the hydrothermal excitation heats the surface of the epoxy resin through a hydrothermal excitation source.

[0016] As a preferred embodiment of the epoxy resin defect detection method based on hydrothermal excitation described in the present invention, the hydrothermal excitation includes applying hydrothermal excitation in the range of 50 degrees Celsius to 90 degrees Celsius to the surface of the epoxy resin through a thermostatic and constant temperature hydrothermal reactor for 5 to 30 minutes to stimulate bubble defects in the material.

[0017] As a preferred solution of the epoxy resin defect detection method based on hydrothermal excitation described in the present invention, wherein: the acquisition of thermal image data of the epoxy resin surface after hydrothermal excitation includes acquiring image data at a preset frame rate through an infrared thermal imager.

[0018] As a preferred solution of the epoxy resin defect detection method based on hydrothermal excitation described in the present invention, the image processing includes background subtraction, noise removal and image enhancement.

[0019] As a preferred embodiment of the epoxy resin defect detection method based on hydrothermal excitation described in the present invention, the epoxy resin defect detection method based on hydrothermal excitation as described in claim 6 is characterized in that the defects identified on the epoxy resin surface are abnormal areas on the thermal image.

[0020] Another object of the present invention is to provide an epoxy resin defect detection system based on hydrothermal excitation, which can solve the problem that data transmission in existing distribution network operations needs to ensure security and confidentiality by constructing a remote secure communication system for distribution network operations, and that using a third-party platform is not conducive to data confidentiality.

[0021] To solve the above technical problems, the present invention provides the following technical solutions: an epoxy resin defect detection system based on hydrothermal excitation, comprising: a hydrothermal excitation module, an image acquisition module, an image processing module and a defect recognition module; the hydrothermal excitation module is used to perform hydrothermal excitation on the epoxy resin surface; the image acquisition module is used to collect thermal image data of the epoxy resin surface after hydrothermal excitation; the image processing module is used to perform image processing on the thermal image data; the defect recognition module is used to analyze the processed thermal image and identify defects on the epoxy resin surface.

[0022] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-mentioned epoxy resin defect detection method based on hydrothermal excitation when executing the computer program.

[0023] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the epoxy resin defect detection method based on hydrothermal excitation as described above.

[0024] Beneficial effects of the present invention: The epoxy resin defect detection method based on hydrothermal excitation provided by the present invention adopts water bath heating and uses water as a heat transfer medium to achieve precise temperature control. Due to the large heat capacity of water, it can store a large amount of thermal energy and can slowly and evenly transfer this thermal energy to the sample to be tested, thereby avoiding the problems of local overheating and uneven temperature that may be caused by direct heating. Water bath heating can provide a uniform heating environment, which is helpful for infrared detection and ensures that all parts of the sample are heated at the same rate, thereby obtaining more consistent and reliable detection results. When using water bath heating for infrared detection, water can act as a buffer to prevent overheating of samples or equipment, which helps to protect samples and users and avoid the risk of burns or other accidents. Improve the sensitivity of infrared detection. In infrared thermal wave nondestructive testing technology, water bath heating can better excite thermal waves inside the sample, so that potential defects or damage are more easily detected by infrared thermal imagers. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0026] Figure 1 An overall flow chart of an epoxy resin defect detection method based on hydrothermal excitation is provided for one embodiment of the present invention.

[0027] Figure 2 An image of sample 1 of an epoxy resin defect detection method based on hydrothermal excitation provided by an embodiment of the present invention without water bath heating.

[0028] Figure 3 An image diagram of sample 1 being heated in a water bath according to an epoxy resin defect detection method based on hydrothermal excitation provided in one embodiment of the present invention.

[0029] Figure 4 An image of sample 2 of an epoxy resin defect detection method based on hydrothermal excitation provided by an embodiment of the present invention without water bath heating.

[0030] Figure 5 An image diagram of sample 2 being heated in a water bath according to an epoxy resin defect detection method based on hydrothermal excitation provided in one embodiment of the present invention.

[0031] Figure 6 A maximum-minimum and radiation value-time double logarithmic curve diagram of an epoxy resin defect detection method based on hydrothermal excitation provided by an embodiment of the present invention.

[0032] Figure 7 A maximum-minimum and radiation value-time linear curve diagram of an epoxy resin defect detection method based on hydrothermal excitation provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0033] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work should fall within the scope of protection of the present invention.

[0034] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0035] Example 1

[0036] Reference Figure 1 , as an embodiment of the present invention, provides an epoxy resin defect detection method based on hydrothermal excitation, comprising:

[0037] S1: hydrothermal stimulation of epoxy resin surface;

[0038] S2: Collect thermal image data of epoxy resin surface after hydrothermal excitation;

[0039] S3: performing image processing on the thermal image data;

[0040] S4: Analyze the processed thermal image and identify defects on the epoxy resin surface.

[0041] Before the epoxy resin surface is hydrothermally stimulated, it also includes:

[0042] Place the epoxy resin sample in the sample tank of the hydrothermal reactor.

[0043] It should be noted that a standard epoxy resin sample was selected, a cylinder with a radius of 2 cm, a height of 1.5 cm, a defect depth of 0.5 mm, and a defect size of 0.5 mm.

[0044] Prepare infrared thermal imaging equipment and a hydrothermal excitation source, which can be a high-power halogen lamp or other heating equipment. At the same time, ensure that the surface of the epoxy resin sample is clean and unobstructed so that the infrared thermal imager can clearly capture the temperature changes on the surface.

[0045] Hydrothermal excitation heats the epoxy resin surface through a hydrothermal excitation source.

[0046] It should be noted that the hydrothermal excitation process includes:

[0047] A1 Preparation: First, make sure the working environment of the hydrothermal reactor is clean and tidy without any debris. Then, add an appropriate amount of water to the hydrothermal reactor according to the experimental needs. Note that the amount of water should be able to cover the bottom of the container to be heated, but not too high to avoid overflow.

[0048] A2. Start-up operation: Turn on the power and adjust the temperature controller to the required temperature. After the water temperature reaches the set temperature, you can start the experiment.

[0049] A3. Place the sample: Place the sample to be heated in the hydrothermal reactor and ensure that the sample is in full contact with water to ensure uniform temperature conduction.

[0050] A4. Heating process: When heating, water bath heating can avoid the problems of local overheating and uneven temperature that may be caused by direct heating.

[0051] A5. Temperature control: Use the temperature controller to precisely control the water temperature.

[0052] A7.Safety measures: Safety regulations should be followed during operation to prevent burns, etc.

[0053] A8. End of operation: After the experimental operation is completed, the hydrothermal reactor should be turned off in time and the power supply should be disconnected.

[0054] This embodiment uses epoxy resin as sample 1 and sample 2 for experiment. Sample 1 is a cylindrical epoxy resin with a radius of 2 cm and a height of 1.5 cm (the proportion of aluminum powder is 68%), a defect depth of 0.5 mm and a size of 0.8 mm. (The best effect is achieved when the heating parameters are 80°C and 8 minutes).

[0055] Sample 2 parameters are cylindrical epoxy resin (doped with aluminum powder at a ratio of 68%) with a radius of 3 cm and a height of 2 cm, a defect depth of 4 mm and a size of 1.8 mm. (The best effect is achieved when the heating parameters are 90°C and 10 minutes).

[0056] It should be noted that when the sample radius is 2cm-3cm, the height is 1-2cm, the defect depth is 0.2mm-2mm, the temperature is 60-80℃, and the time is 5-10min; when the sample radius is 3cm-4cm, the height is 2-3cm, the defect depth is 2mm-3mm, the temperature is 90-100℃, and the time is 15-30min.

[0057] Using a thermostatically controlled hydrothermal reactor, the quantitative detection time is 5min, 10min, 15min, and 30min at 50°, 60°, 70°, 80°, and 90°, and the pressure is normal atmospheric pressure. The defect is a bubble defect, but the bubble size is different, and it can basically be seen at 80° and 10min.

[0058] Heating can be local or uniform across the entire specimen. The purpose of heating is to create a temperature gradient that varies due to defects within the material.

[0059] Local means that if the sample size is larger than the volume of the hydrothermal reactor, the defective part of the sample will be locally heated.

[0060] Water bath heating provides a uniform heating environment because it ensures that all parts of the sample are heated at the same rate.

[0061] According to the characteristics of thermal images, in infrared thermal imaging detection, if the thermal image shows that the temperature distribution of the inspected equipment or object is uniform, without obvious hot spots or cold spots, it can be considered that the heating is uniform.

[0062] After heating is completed, an infrared thermal imager is used to monitor the temperature rise of the epoxy resin surface in real time. The infrared thermal imager can capture the difference in heat conduction caused by internal defects in the material, thus forming a visible temperature difference area on the thermal image.

[0063] When the predetermined time point is reached, the method of the present invention is set at 10 minutes. After reaching this time point, it is determined that the heating is completed.

[0064] The infrared camera collects image data at a certain frame rate. This data can be used for subsequent analysis to determine the location and size of defects.

[0065] The collected thermal image data needs to be processed by professional software. This may include steps such as background subtraction, noise removal, and image enhancement to improve the identifiability of defects.

[0066] By analyzing the processed thermal images, defects in the epoxy resin surface can be identified. Defects usually appear as abnormal areas on the thermal image, such as abnormal increases or decreases in temperature.

[0067] It should be noted that the collected infrared images are processed by the transfer station, such as edge detection, Gaussian blur, and sharpening.

[0068] Gaussian blur reduces image noise and detail levels by convolving with the normal distribution, blurring the boundaries and contours of the image, creating a visual effect similar to looking through frosted glass. Gaussian blur is a low-pass filter for images, which retains the low-frequency information of the image and removes high-frequency information (details and edges).

[0069] Gaussian blur can effectively reduce the noise in the image by smoothing the image, making the image cleaner.

[0070] Edge detection aims to identify boundaries or abrupt changes in pixel intensity in an image, capturing areas where brightness changes dramatically. These boundaries or "edges" may represent object outlines, texture transitions, or significant changes in surface orientation. The goal of edge detection is to find all significant edges in an image, or specific edges, such as identifying the boundary between two different regions.

[0071] It should be noted that the pixel brightness of an infrared image represents the temperature of the object surface. Edge detection can reveal areas in the image where the temperature changes significantly and enhance the local features of the image.

[0072] Infrared images are often affected by low signal-to-noise ratio, low resolution, poor contrast and blurred edges. Edge detection technology can improve image quality and image usability by enhancing edge information. Edge detection can enhance local features of images, such as edges, corners and textures, which are critical for subsequent image analysis and recognition tasks.

[0073] Edge detection can extract key features in an image, such as the outline of an object, which is very important for subsequent image analysis and processing.

[0074] Sharpening enhances the edge information in the image, improves the clarity and resolution of the image, and makes the details more prominent. The essence of sharpening is to increase the contrast of the edges of image details, making the image appear sharp and clear.

[0075] Sharpening enhances the edges and details in an image, making it appear clearer.

[0076] It should be noted that sharpening can enhance the edges and details in the image, making the image look clearer, which is especially important for infrared images because infrared images usually have low contrast and unclear details. By enhancing the edge information in the image, sharpening can better show the outline and detail characteristics of the defect. Infrared images are often affected by noise and blur, and sharpening can reduce these unfavorable factors and improve the overall quality of the image. Since infrared images usually have a low signal-to-noise ratio, the sharpening algorithm has a noise suppression function while enhancing the image details. The defect features of the infrared image after sharpening are more obvious, which can improve the recognition rate of the system.

[0077] By collecting infrared thermal images, after the collection is completed, the images are processed by edge detection, Gaussian blur, sharpening, etc. These image processing methods have no order of precedence and can be debugged simultaneously or individually to intuitively observe the location of defects in the samples.

[0078] Example 2

[0079] According to an embodiment of the present invention, a hydrothermal excitation-based epoxy resin defect detection system is provided, comprising:

[0080] Hydrothermal stimulation module 100, image acquisition module 200, image processing module 300 and defect recognition module 400;

[0081] The hydrothermal excitation module 100 is used to perform hydrothermal excitation on the epoxy resin surface;

[0082] The image acquisition module 200 is used to collect thermal image data of the epoxy resin surface after hydrothermal excitation;

[0083] The image processing module 300 is used to perform image processing on thermal image data;

[0084] The defect recognition module 400 is used to analyze the processed thermal image and identify defects on the epoxy resin surface.

[0085] Example 3

[0086] An embodiment of the present invention is different from the first two embodiments in that:

[0087] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.

[0088] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, system or device (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, system or device and execute the instructions), or in conjunction with these instruction execution systems, systems or devices. For the purpose of this specification, "computer-readable medium" can be any system that can contain, store, communicate, propagate or transport a program for use by an instruction execution system, system or device, or in conjunction with these instruction execution systems, systems or devices.

[0089] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic systems), a portable computer disk case (magnetic systems), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), an optical fiber system, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or, if necessary, processing in another suitable manner, and then stored in a computer memory.

[0090] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0091] Example 4

[0092] Reference Figure 2-Figure 7 , which is an embodiment of the present invention, provides an epoxy resin defect detection method based on hydrothermal excitation. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through simulation experiments.

[0093] Figure 2 , Figure 3 This is a comparative test of sample 1. The parameters of sample 1 are a cylindrical epoxy resin (doped with aluminum powder at a ratio of 68%) with a radius of 2 cm and a height of 1.5 cm. The defect depth is 0.5 mm and the size is 0.8 mm. After the sample is treated with a water-proof bag, it is placed in a hydrothermal reactor for heating. The heating is heated to 80° for 10 minutes and then stopped. The experimental results are shown in the figure. The left side shows the result without water bath heating, and the right side shows the result with water bath heating. Figure 4 , 5 The operation is as described above. The parameters of sample 2 are cylindrical epoxy resin (doped with aluminum powder at a ratio of 68%) with a radius of 3 cm and a height of 2 cm, a defect depth of 4 mm and a size of 1.8 mm.

[0094] The water bath heating and non-water bath heating of sample 1 were compared. The experimental results show that the sample heated by water bath is more effective than the sample without heating. The same amount of comparative experiments were conducted at 90°C and 10 minutes. The infrared detection images were obtained. The defects of the sample heated by water bath are obviously clearer. The experimental results are shown in Table 1.

[0095] Table 1 Comparison of experimental results

[0096]

[0097] As shown in Table 1, the double logarithm of the radiation value-time at the defect. Figure 6 , 7 It can be seen that in the stage of rising radiation value, the higher the radiation peak value, the deeper the defect depth is; in the stage of falling radiation value, it can be concluded that at the minimum value, the higher the radiation value, the deeper the defect.

[0098] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for detecting epoxy resin defects based on hydrothermal excitation, characterized in that: include: Hydrothermal stimulation of the epoxy resin surface; Collect thermal image data of epoxy resin surface after hydrothermal excitation; Performing image processing on thermal image data; The processed thermal images were analyzed to identify defects on the epoxy surface.

2. The epoxy resin defect detection method based on hydrothermal excitation according to claim 1, characterized in that: Before the epoxy resin surface is subjected to hydrothermal excitation, the method further comprises: Place the epoxy resin sample in the sample tank of the hydrothermal reactor.

3. The epoxy resin defect detection method based on hydrothermal excitation according to claim 2, characterized in that: The hydrothermal excitation heats the surface of the epoxy resin through a hydrothermal excitation source.

4. The epoxy resin defect detection method based on hydrothermal excitation according to claim 3, characterized in that: The hydrothermal excitation includes applying hydrothermal excitation in the range of 50 degrees Celsius to 90 degrees Celsius to the surface of the epoxy resin through a thermostatically adjustable and constant temperature hydrothermal reactor for 5 to 30 minutes to stimulate bubble defects in the material.

5. The epoxy resin defect detection method based on hydrothermal excitation according to claim 4, characterized in that: The collecting of thermal image data of the epoxy resin surface after hydrothermal excitation includes collecting image data at a preset frame rate by using an infrared thermal imager.

6. The epoxy resin defect detection method based on hydrothermal excitation according to claim 5, characterized in that: The image processing includes background subtraction, noise removal and image enhancement.

7. The epoxy resin defect detection method based on hydrothermal excitation according to claim 6, characterized in that: The defects on the epoxy resin surface are identified as abnormal areas on the thermal image.

8. A system using the epoxy resin defect detection method based on hydrothermal excitation as claimed in any one of claims 1 to 7, characterized in that: include: A hydrothermal excitation module (100), an image acquisition module (200), an image processing module (300), and a defect recognition module (400); The hydrothermal excitation module (100) is used to perform hydrothermal excitation on the surface of epoxy resin; The image acquisition module (200) is used to acquire thermal image data of the epoxy resin surface after hydrothermal excitation; The image processing module (300) is used to perform image processing on thermal image data; The defect recognition module (400) is used to analyze the processed thermal image and identify defects on the surface of the epoxy resin.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the epoxy resin defect detection method based on hydrothermal excitation according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the epoxy resin defect detection method based on hydrothermal excitation according to any one of claims 1 to 7 are implemented.

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