Camouflage Technology Research Articles

Research on Infrared Camouflage Technology for Direct Buried Heat Pipelines

The threats of infrared reconnaissance, surveillance, and guidance weapons to directly buried heat pipelines are increasing with the development of modern infrared technology. Therefore, it is necessary to conduct extensive research on thermal infrared camouflage technology for directly buried heat pipelines. Based on the principle of heat transfer, this paper establishes a numerical model of the temperature of the directly buried heat pipe and analyzes the influence of the buried depth of the pipe, the mixing of cold and hot fluids, and the coating of thermal insulation materials on the thermal infrared camouflage effect. The analysis results provide an important reference for the thermal infrared camouflage design of the directly buried heat pipe.

Development of fiber-based active thermal infrared camouflage textile

The implementation of complete infrared (IR) camouflaging/disguise technology requires three-dimensional (3D) thermal camouflage that can respond rapidly to changes in the ambient temperature and operate uniformly at various angles. In this study, a fiber-based IR conductive material was developed that responds sensitively and rapidly to changes in the ambient temperature. Moreover, the material can be woven into various patterns, enabling the IR camouflage of a 3D wearable garment. A full-color IR radiation image is produced by generating three different IR intensities based on the voltage applied to a far-IR fiber. The use of passive camouflage technology enables objects to be hidden from their backgrounds, while active camouflage technology permits objects to be camouflaged against changing surrounding backgrounds or to be recognized as arbitrary objects (e.g., car, animal, or plant). It is expected that this differentiated camouflaging/disguise technology based on IR imaging can be applied to various industrial, military, and new scientific fields.

Evaluation of infrared camouflage effectiveness via a multi-fractal method

This paper reports an alternative approach to the evaluation of infrared camouflage effectiveness via a multi-fractal method. By calculating multi-fractal spectra of the target region and the background regions in an infrared image, the spectrum shape features and the discrete Fréchet distances among these spectra were used to analyze the camouflage effectiveness of the target qualitatively and quantitatively, and the correlation coefficients of the spectra were further used as the index of camouflage effectiveness. It was found that the camouflaged target had better camouflage effectiveness than the target without camouflage in the same one background, and the same one camouflaged target had different camouflage effectiveness in different backgrounds. On the whole, the target matching well with its background had high camouflage effectiveness value. This approach can expand the application of multi-fractal theory in infrared camouflage technology, which should be useful for the research of infrared camouflage materials, the design of camouflage patterns as well as the deployment of military equipment in battlefield.

Dynamic thermal camouflage via a liquid-crystal-based radiative metasurface

Abstract Thermal camouflage, which is used to conceal objects in the infrared vision for confrontation with infrared detection in civilian or military applications, has garnered increasing attraction and interest recently. Compared with conductive thermal camouflage, that is to tune heat conduction to achieve equivalent temperature fields, radiative thermal camouflage, based on emissivity engineering, is more promising and shows much superiority in the pursuit of dynamic camouflage technology when resorting to stimuli-responsive materials. In this paper, we demonstrate the emissivity-engineered radiative metasurface to realize dynamic thermal camouflage functionality via a flying laser heat source on the metal-liquid-crystal-metal (MLCM) platform. We employ a rigorous coupled-wave algorithm to calculate the surface emissivity of Au/LC/Au microstructures, where the LC-orientation angle distribution is quantified by minimizing the emitted thermal energy standard deviation throughout the whole plate. Emissivity engineering on the MCLM platform is attributed to multiple magnetic polariton resonance, and agrees well with the equivalent electric circuit analysis. Through this electrical modulation strategy, the moving hot spot in the original temperature field is erased and a uniform temperature field is observed in the infrared camera instead, demonstrating the very good dynamic thermal camouflage functionality. The present MLCM-based radiative metasurface may open avenues for high-resolution emissivity engineering to realize novel thermal functionality and develop new applications for thermal metamaterials and meta-devices.

LSTM Based Phishing Detection for Big Email Data

In recent years, cyber criminals have successfully invaded many important information systems by using phishing mail, causing huge losses. The detection of phishing mail from big email data has been paid public attention. However, the camouflage technology of phishing mail is becoming more and more complex, and the existing detection methods are unable to confront with the increasingly complex deception methods and the growing number of emails. In this article, we proposed an LSTM based phishing detection method for big email data. The new method includes two important stages, sample expansion stage and testing stage under sufficient samples. In the sample expansion stage, we combined KNN with K-Means to expand the training data set, so that the size of training samples can meet the needs of in-depth learning. In the testing stage, we first preprocess these samples, including generalization, word segmentation and word vector generation. Then, the preprocessed data is used to train a LSTM model. Finally, on the basis of the trained model, we classify the phishing emails. By experiment, we evaluate the performance of the proposed method, and experimental results show that the accuracy of our phishing detection method can reach 95 percent.

Functional Polymer Matrix Composites for Structural and Stealth Applications

Applications of fiber-reinforced polymer matrix composites are increasing in aerospace industry due to their excellent characteristics such as low density, high tensile strength and modulus and fatigue strength. Its tremendous mechanical and electrical properties lead to specific applications in stealth and camouflage technology. In the present study, fabrication of functional radar absorbing structures (RAS) has been done and they are structurally characterized and analyzed. In the fabricated RAS, glass fiber is used as reinforcement and epoxy resin is used as a matrix, with various conducting and magnetic functional materials as fillers. To find out the effect of post-curing, one set of composites was prepared without post-curing and another set was prepared with post-curing. Measured properties indicated that post-cured composites have better mechanical properties than without post-cured composites.

Algorithmic anxiety: Masks and camouflage in artistic imaginaries of facial recognition algorithms

This paper discusses prominent examples of what we call “algorithmic anxiety” in artworks engaging with algorithms. In particular, we consider the ways in which artists such as Zach Blas, Adam Harvey and Sterling Crispin design artworks to consider and critique the algorithmic normativities that materialize in facial recognition technologies. Many of the artworks we consider center on the face, and use either camouflage technology or forms of masking to counter the surveillance effects of recognition technologies. Analyzing their works, we argue they on the one hand reiterate and reify a modernist conception of the self when they conjure and imagination of Big Brother surveillance. Yet on the other hand, their emphasis on masks and on camouflage also moves beyond such more conventional critiques of algorithmic normativities, and invites reflection on ways of relating to technology beyond the affirmation of the liberal, privacy-obsessed self. In this way, and in particular by foregrounding the relational modalities of the mask and of camouflage, we argue academic observers of algorithmic recognition technologies can find inspiration in artistic algorithmic imaginaries.

Thermal camouflage based on the phase-changing material GST

Camouflage technology has attracted growing interest for many thermal applications. Previous experimental demonstrations of thermal camouflage technology have not adequately explored the ability to continuously camouflage objects either at varying background temperatures or for wide observation angles. In this study, a thermal camouflage device incorporating the phase-changing material Ge2Sb2Te5 (GST) is experimentally demonstrated. It has been shown that near-perfect thermal camouflage can be continuously achieved for background temperatures ranging from 30 °C to 50 °C by tuning the emissivity of the device, which is attained by controlling the GST phase change. The thermal camouflage is robust when the observation angle is changed from 0° to 60°. This demonstration paves the way toward dynamic thermal emission control both within the scientific field and for practical applications in thermal information.

Cephalopods Between Science, Art, and Engineering: A Contemporary Synthesis

ABSTRACT Cephalopods are outstanding animals. For centuries, they have provided a rich source of inspiration to many aspects of human cultures, from art, history, media and spiritual beliefs to the most exquisite scientific curiosity. Given their high esthetical value and ‘mysteriously’ rich behavioral repertoire they have functioned as boundary objects (or subjects) connecting seemingly distinct thematic fields. Interesting aspects of their being span from the rapid camouflaging ability inspiring contemporary art practices, to their soft and fully muscular body that curiously enough inspired both gastronomy and (soft) robotics. The areas influenced by cephalopods include ancient mythology, art, behavioural science, neuroscience, genomics, camouflage technology and bespoken robotics. Although these might seem far related fields, in this manuscript we want to show how the increasing scientific and popular interest in this heterogeneous class of animals have indeed prompted a high level of integration between scientific, artistic and sub-popular culture. We will present an overview of the birth and life of cephalopod investigations from the traditional study of ethology, neuroscience, and biodiversity to the more recent and emerging field of genomics, material industry and soft robotics. Within this framework, we will attempt to capture the current interest and progress in cephalopod scientific research that lately met both the public interest and the ‘liberal arts’ curiosity.

An Information Theory-Inspired Strategy for Design of Re-programmable Encrypted Graphene-based Coding Metasurfaces at Terahertz Frequencies

Inspired by the information theory, a new concept of re-programmable encrypted graphene-based coding metasurfaces was investigated at terahertz frequencies. A channel-coding function was proposed to convolutionally record an arbitrary information message onto unrecognizable but recoverable parity beams generated by a phase-encrypted coding metasurface. A single graphene-based reflective cell with dual-mode biasing voltages was designed to act as “0” and “1” meta-atoms, providing broadband opposite reflection phases. By exploiting graphene tunability, the proposed scheme enabled an unprecedented degree of freedom in the real-time mapping of information messages onto multiple parity beams which could not be damaged, altered, and reverse-engineered. Various encryption types such as mirroring, anomalous reflection, multi-beam generation, and scattering diffusion can be dynamically attained via our multifunctional metasurface. Besides, contrary to conventional time-consuming and optimization-based methods, this paper convincingly offers a fast, straightforward, and efficient design of diffusion metasurfaces of arbitrarily large size. Rigorous full-wave simulations corroborated the results where the phase-encrypted metasurfaces exhibited a polarization-insensitive reflectivity less than −10 dB over a broadband frequency range from 1 THz to 1.7 THz. This work reveals new opportunities for the extension of re-programmable THz-coding metasurfaces and may be of interest for reflection-type security systems, computational imaging, and camouflage technology.

A honeycomb-like three-dimensional metamaterial absorber via super-wideband and wide-angle performances at millimeter wave and low THz frequencies

Achieving wideband absorption via three-dimensional (3D) metamaterials has revealed as a new emerging innovative field of research, especially in recent years. Here, a novel 3D metamaterial absorber (MA) having a sixfold symmetry is designed which consists of periodic resistive honeycomb-like units. The proposed 3D MA exhibits a strong absorptivity above 90% in the widest bandwidth ever reported to the authors’ knowledge from 50 to 460 GHz (the bandwidth ratio larger than 1:9), covering both millimeter wave and low -terahertz spectra. To understand the physical mechanism of absorption, the electric field and surface current distributions, the power loss density as well as the deteriorating effects of the high-order Floquet modes are monitored and discussed. As a distinctive feature in comparison to the similar 3D MAs, our engineered absorber provides multiple resonances, contributing to further broadening of the operating bandwidth. In addition, it is shown that the honeycomb-like MA retains its polarization-insensitive absorption in a wide range of incident wave angles and polarization angles. Due to flexibility of the design, these superior performances can be simply extended to terahertz, infrared and visible frequencies, potentially leading to many promising applications in imaging, sensing, and camouflage technology.

Vanadium dioxide nanopowders with tunable emissivity for adaptive infrared camouflage in both thermal atmospheric windows

Vanadium dioxide, which has been demonstrated as negative differential thermal emissivity materials for emissivity engineering application, is regarded as the most important and promising material for adaptive infrared camouflage. This study describes the synthesis and characterization of high purity, uniform VO2 nanopowders by a single-step hydrothermal method and their thermal polymorphism. A dramatic phase transition of the monoclinic VO2 nanopowders to a tetragonal phase upon heating and the accompanying change in the IR emissivity are demonstrated. Importantly, we demonstrate the tunability of the infrared radiation intensity of VO2 nanopowders in both mid- and far-IR thermal atmospheric windows, for the first time. The structural transition is analyzed by variable temperature XRD and temperature-dependent Raman spectroscopy. Furthermore, an unexpected structural change in the same region of the sample was observed in a transmission electron microscope, which provides a direct mechanistic understanding of the infrared emissivity variation. Our study makes a significant contribution to the state-of-the-art in thermal camouflaging, because this study demonstrates that the VO2 nanopowders can be extremely promising camouflage materials in the area of adaptive infrared camouflage technology both in the far-infrared and mid-infrared regions and the material is suitable for substrates with large surface areas and/or complex morphologies.

Microwave Absorbing Properties of MnAlFe Magnetic Powder

MnAlFe alloy was prepared by the combined use of smelting, high-energy ball milling and tempering heat treatment process. The phase composition and microwave absorbing properties of MnAlFe alloy were investigated by X-ray diffractometer(XRD) and vector network analyzer. The results show that the powders consist of Al8Mn5 single phase with different Fe content; the dielectric loss and the magnetic loss increases with the addition of Fe, the resonant frequency and absorption peak of ε″ and μ″ moves towardslower frequency region simultaneously. The (Al8Mn5)99Fe exhibits preferably comprehensive microwave absorbing properties in the range of 6-18 GHz. The value of the minimum reflectivity and absorption peak frequency with the coating thickness of 1.5 mm, are -23.1 dB, 15.04 GHz respectively. Owing to the wide applications of electromagnetic waves in the range of 1–4 GHz for mobile phone, local area network, radar systems and so on over the past few decades, the serious problems of the electromagnetic interference and electromagnetic compatibility have become increasingly prominent in recent years. Microwave absorbing materials, which possess special performance for absorbing electromagnetic wave, have been applied in both civil and military fields and play an important role in camouflage technology. In military field, stealth technology to reduce and eliminate the electromagnetic radiation and electromagnetic interference resulting from the broad applications of various kinds of electronic and microwave instruments, stealth technology plays an important strategic role in the wars in future[1-2]. The microwave absorbing materials can be used to reduce radar cross section for military use. For this reason, the microwave absorbing material is vitally important for both civil and military fields[3-7]. In view of this utilization, excellent microwave absorbing materials should exhibit strong microwave absorption properties over a wide frequency range and need to be thin and light in weight. It has an important meaning to the application of magnetic microwave absorbing materials. MnAl alloy can be used as microwave absorbent. It has properties such as light in weight, good thermal stability and corrosion resistance[8-11]. But as permanent magnets, MnAl has shortcomings such as their difficulties of fabrication and high costs that prevent them from being used as permanent magnets. A great value would be brought to either theory or practice through proper treatments as further improvement in properties. In this paper, we will discuss the effects of changing relative content of Fe on absorption properties of Al8Mn5 alloy.

Optical Digital Imitation Painting Design Based on Self-Adaptive Image Feature

Based on the study of existing digital imitation camouflage technology, we propose a kind of optical digital imitation camouflage design algorithm which is based on the characteristic of self-adaptive image. Picking main color feature of the background by using K-means clustering algorithm, counting the shape characteristics of each main color spots by separating layers, we generated digital camouflage pattern automatically by segmenting the background region characteristics and fill the background color image according to the statistics expected value. The simulation results show that, the digital camouflage generated automatically is blend well with the background .It keeps the background color and shape features, so has good camouflage effect. This algorithm can also provide the basic algorithm foundation for digital deformation camouflage.

A New Design of Digital Camouflage Spray Device

The digital camouflage technology is a new camouflage technique of military engineering. It sprays the Mosaic block of different color on the surface after permutation and combination according to certain rules. But in present, the current technology still takes artificial spraying method. This method cant adapt the present need of camouflage technique for military engineering whether spraying effect or spraying efficiency. For this reason, an intelligentized digital camouflage spraying device of cartesian coordinate robot is designed. The study could supply important references for theory research and project implementation of military digital camouflage technology.

Ground target recognition based on imaging LADAR point cloud data

The battlefield scenario continues to grow in complexity as the use of high-resolution sensors and precision strike weapons has forced the increased use of concealment and camouflage technology to improve weapon survivability. Thus, automatic target recognition (ATR) capability is becoming increasingly important to the Defense Community. There are two fundamental challenges in ATR for military applications. The first is the massive data loads generated by modern high-resolution sensors, which can quickly escalate to unmanageable proportions. The second challenge is camouflage, concealment, and deception, this further increases the complexity of ATR and moti

Study on the Camouflaged Target Detection Method Based on 3D Convexity

To effectively detect the camouflaged target in the complex background, the target detection method based on 3D convexity is proposed in this article. This method uses a new operator which can fully utilize the representative image gray level represented by the convexity structure of the target, set up appropriate threshold to eliminate the influence of the background noise by the median filtering through the gray face of the target image, and realize the effective detection and identification of the convexity target. The experiment result shows that this method could successively detect the camouflaged targets in the complex background, better than classic edge detection method. As a new camouflaged target detection and evaluation technology, this method can provide necessary factors for the design and implementation of the camouflage technology, and promote the development of the camouflage technology.

Polarization patterns hide and display using photoinduced anisotropy of photochromic fulgide

Photoinduced anisotropy of a photochromic pyrrylfulgide/PMMA film was investigated by using two linearly polarized beams. Excitation by linearly polarized light induces into the film an optical axis that has the same polarization as the excitation beam. This causes a change of the transmittance and of the polarization state of the detection beam. With a microscope a matrix of 4x4 light spots with different polarizations were recorded in the pyrrylfulgide/PMMA film. If readout with non-polarized light, the matrix of light spots show no information pattern. However, when readout with differently polarized lights, different patterns can be displayed. The experiment demonstrates that pyrrylfulgide/PMMA films can be used to hide two differently polarized patterns, which may be applied in camouflage technology.

Polarization Patterns Control Based on Photoinduced Anisotropyof Photochromic Fulgide

We investigate the photoinduced anisotropy of a photochromicmaterial of pyrrylfulgide/PMMA films. It is proven that when the filmis illuminated with a linear polarization light, an optical axis thathas the same polarization as the excitation light could be induced inthe film. A matrix of light spots with different polarizations isrecorded on the pyrrylfulgide/PMMA film. When reading out withnon-polarization light, the matrix of light spots shows no informationof patterns. However, when reading out with different linearpolarization lights, different patterns could be observed. Theexperiment confirms that the pyrrylfulgide/PMMA film could be used torecord two different polarization patterns in a matrix of spots. Thisproperty may be applied in camouflage technology.