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Copyright of Systems Engineering & Electronics is the property of Journal of Systems Engineering & Electronics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Achieving multiband camouflage through the integration of ultraviolet (UV) absorption, visible light camouflage, and infrared signature modulation has long posed a challenge in material science. Leveraging the polarizonic concept, the study demonstrates, for the first time, the broadband camouflage system that adheres to the golden rule by achieving near‐perfect UV absorption (99.96%) across the UV‐A, UV‐B, and UV‐C ranges. This system is also visibly colored to blend with its environment and leaves no thermal signature in the IR. Traditionally, earth‐abundant metals, such as iron, are not considered viable for plasmonic color applications due to their high optical losses and oxidation susceptibility that degrade their optical properties. However, contrary to conventional assumptions, the study introduces a sustainable color palette derived from transparent and grey earth‐abundant materials, offering novel approaches to color, stealth, and energy‐harvesting metasurface‐driven technologies. The simple, cost‐effective, and environmentally friendly co‐sputtering fabrication method highlights the impact of the polarizonic concept and its novel dipolar image interference phenomena on flexible substrates therefore passivating the way for scalable and sustainable solutions in next‐generation camouflage systems with potential applications in UV‐protective coatings, photolithography, and anti‐counterfeiting technologies. [ABSTRACT FROM AUTHOR]

The design and development of efficient microwave-absorbing and electromagnetic interference (EMI) shielding materials and structures to conceal electromagnetic (EM) waves remains a consistent and challenging task. Despite advancements in materials science and microwave engineering, there is a need for optimized materials that offer both effective microwave absorption and EMI shielding while minimizing material layer thickness. This research aims to address this gap by utilizing the firefly algorithm (FFA) to predict the optimal medium properties and thickness of microwave-absorbing and EMI shielding materials under specific constraints. In this context, a comprehensive investigation was carried out at the X-band involving numerical and experimental EM characterization of novel lightweight fiber-based samples. Additionally, the FFA has been applied to optimize these fiber-based microwave structures within the given constraints. Two separate objective functions (OBF) targeting minimum sample thickness, maximum microwave absorption, and shielding effectiveness (SE) bandwidth have been integrated into the FFA to address the thickness–bandwidth trade-off issue. Subsequently, resistive ink-coated glass fiber (IGF) and ink-coated mesh fiber (IMF) were developed and characterized based on the optimal solutions provided by the FFA. Consequently, an optimized IMF sample provides a minimum reflection coefficient (RC) of −19.0 dB at 10.7 GHz with a bandwidth of 2.8 GHz (9.6 to 12.4 GHz) below the −10 dB threshold. Besides, the optimal IGF sample achieves maximum SE of 11 dB at thickness of only 0.8 mm and covers the entire operating band. Furthermore, the response of the proposed structure was assessed for various oblique angles of incidence, revealing significant potential for various practical applications. A strong correlation between measured and theoretical findings underscores the potential of the proposed approach in realizing efficient microwave stealth and EMI shielding materials. [ABSTRACT FROM AUTHOR]

Metamaterials (MTMs) are synthetic structures known for their ability to control electromagnetic wave propagation, offering innovative solutions for reducing the radar cross-section (RCS) of objects. This paper proposes an agile bilayer MTM to reduce the RCS. Each layer consists of identical agile MTM unit cells embedded with switches to achieve agility. Depending on the switch state, we can obtain two types of unit cells: connected (ON state) and disconnected (OFF state), which exhibit two different behaviors. The switches are controlled using an external command system. By independently adjusting the switching states (ON/OFF) of the two layers, six agile reflection frequency stop bands are generated, corresponding to the four possible configurations of ON–ON, ON–OFF, OFF–ON, and OFF–OFF, and their reflection and transmission ranges are controlled. This design has the capability to control six distinct frequency bands with a − 1- dBm RCS reduction, comprising two bands within the Ku-band (12–18 GHz) and four within the Ka-band (25–40 GHz). [ABSTRACT FROM AUTHOR]

A multifunctional frequency‐selective rasorber (MFSR) with passband stealth performance by using PIN diodes is investigated, which is made up of two reconfigurable components (a lossy layer and transmissive polarization converter surface (lossless layer)). The proposed MFSR shows transmission in‐band and absorption out‐band at working state, but the transparent window is closed to achieve full‐band stealth at nonworking state. Besides, the equivalent circuit model (ECM) is constructed to annotate the operating principle of the designed MFSR. The MFSR indicates a wide cross‐polarized transmission window from 3.71 to 4.38 GHz between two absorption bands at working, meanwhile a broadband copolarized reflection band (S11 < −10 dB) is accomplished in 1.78–5.50 GHz. At nonworking, an ultra‐wideband stealth band is realized in 1.81–7.0 GHz when the absorptivity is over 80%, which has a 117.8% fractional bandwidth (FBW). In addition, the MFSR has a stable oblique incident characteristic (up to 25°). Finally, the sample of the MFSR is manufactured and experimented to demonstrate the availability of this design. [ABSTRACT FROM AUTHOR]

This review is based on the radar cross-section (RCS) reduction techniques, with the prominence of the metasurface and its design. The thorough detail starts with introducing the concepts of the RCS and its reduction techniques. Then, traditional and recent techniques are provided to reduce RCS, emphasizing the scattering and absorption methods. An in-depth analysis of shaping processes and Radar Absorbing Materials (RAM) is provided, which are two standard RCS reduction techniques. It also thoroughly analyses the metamaterial-based RCS reduction, considering both active and passive configurations. The primary aspects covered regarding the utilization of metasurfaces for reducing RCS include profile, conformality, polarization sensitivity, and design complexity. To provide comparison and evaluation, the review includes tabulated information on performance parameters such as the method used, frequency range, size, optimization method, and planar or conformal design of RCS reduction. Additionally, the paper identifies areas within the field that require further in-depth research and investigation.

Achieving the best wideband stealth performance under the limited weight constraint is the goal pursued in stealth aircraft radar absorbing coating（RAC） application schemes design. To meet the need for the integrated application of various kinds of RACs on stealth aircraft， an automatic optimization method for the application programme of RAC was established. Firstly， the electromagnetic fields of the model under different frequencies， azimuths and polarizations were simulated based on the finite difference time domain method. The total electromagnetic field was obtained by normalization and weighted calculation of the electromagnetic fields.Then， the total electromagnetic field was divided according to the specific direction and quantity. Each partition was loaded with the corresponding RAC. The reflection coefficient of the RAC was calculated by the transfer matrix method to superimpose the effect of the RAC on the electromagnetic field. The near-far field transformation was performed on the total electromagnetic field after loading with RAC. In this way， fast computation of radar cross section （RCS） was implemented. Based on the improved simplex method and Karush-Kuhn-Tucker condition， an automatic optimization method is established. The objective function was reducing RCS of the target or reducing weight of the absorbing coating. Finally， taking traveling wave plate as an example， the application plan of three thicknesses of RACs was optimized. The goal of optimization was to reduce total weight of the coating. Compared with the 1.5 mm coating plan， the optimization program can reduce the weight by 50%， with the RCS of traveling wave plate increasing by on more than 1 dB. The optimization effect is remarkable.

High requirements have been placed on the stealth performance of armed helicopters during wartime missions，in order to reduce the probability of the helicopter being found during the task，based on geometric optics method and consistent diffraction theory，the effects of different tail rotor profile thickness，curvature and tail rotor scissors angle on RCS are studied. By comparing different parameters of the tail rotor and the RCS peak value and mean value of the coated absorbing material，the conditions which are more favorable to the stealth of the helicopter tail rotor are determined. When viewed from the ground，the RCS with small tail rotor thickness and small curvature will be reduced appropriately，and the change of scissors angle will lead to the change of RCS peak phase. When the radar is irradiated in parallel，the RCS of tail rotor with smaller thickness is smaller，and the RCS peak value of tail rotor with smaller curvature is smaller. Applying wave absorbing materials on the leading edge and tip of the blade can effectively reduce the overall RCS of the blade. Comprehensive analysis shows that by using the smaller thickness and curvature of the tail rotor，it is beneficial to reduce the RCS of the helicopter tail rotor，and the blade tip surface and the blade leading edge of the absorbing material coating can effectively reduce the overall RCS.

This review is based on the radar cross-section (RCS) reduction techniques, with the prominence of the metasurface and its design. The thorough detail starts with introducing the concepts of the RCS and its reduction techniques. Then, traditional and recent techniques are provided to reduce RCS, emphasizing the scattering and absorption methods. An in-depth analysis of shaping processes and Radar Absorbing Materials (RAM) is provided, which are two standard RCS reduction techniques. It also thoroughly analyses the metamaterial-based RCS reduction, considering both active and passive configurations. The primary aspects covered regarding the utilization of metasurfaces for reducing RCS include profile, conformality, polarization sensitivity, and design complexity. To provide comparison and evaluation, the review includes tabulated information on performance parameters such as the method used, frequency range, size, optimization method, and planar or conformal design of RCS reduction. Additionally, the paper identifies areas within the field that require further in-depth research and investigation. [ABSTRACT FROM AUTHOR]

Modern fighter aircraft increasingly need to conjugate aerodynamic performance and low observability. In this paper, we showcase a methodology for a gradient-based bidisciplinary aero-stealth optimization. The shape of the aircraft is parameterized with the help of a CAD modeler, and we optimize it with the SLSQP algorithm. The drag, computed with the help of a RANS method, is used as the aerodynamic criterion. For the stealth criterion, a function is derived from the radar cross-section in a given cone of directions and weighed with a function whose goal is to cancel the electromagnetic intensity in a given direction. Stealth is achieved passively by scattering back the electromagnetic energy away from the radar antenna, and no energy is absorbed by the aircraft, which is considered as a perfect conductor. A Pareto front is identified by varying the weights of the aerodynamic and stealth criteria. The Pareto front allows for an easy identification of the CAD model corresponding to a chosen aero-stealth trade-off. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Engineering / Cailiao Gongcheng is the property of Journal of Materials Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Understanding the interactions between nanocarriers and plasma proteins is essential for controlling their biological fate. Based on the reported potential of polymeric nanocapsules (NCs) for the targeted delivery of oncological drugs, the main objective of this work has been to investigate how the surface chemical composition influences their protein corona fingerprint. Thus, we developed six NC prototypes with different polymer shells and physicochemical properties and quantified the amount of protein adsorbed upon incubation in human plasma. Using sequential window acquisition of all theoretical mass spectra (SWATH-MS) and following the Minimum Information about Nanomaterial Biocorona Experiments (MINBE) guidelines, we identified different protein corona patterns. As expected, the presence of polyethylene glycol (PEG) in the polymer shell reduced the protein corona, particularly the adsorption of immunoglobulins. However, by comparing the different prototypes, we concluded that the protein adsorption pattern was not exclusively driven by PEG. In fact, a highly PEGylated prototype exhibited intense apolipoprotein IV adsorption. On the other hand, we also observed that polymeric NCs containing 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) exhibited high adsorption of vitronectin, a protein that is known for enhancing the uptake of nanosystems by lung epithelium and several cancer cells. Overall, the gathered information allowed us to identify promising polymeric NCs with an expected prolonged circulation time, enhanced tumor targeting, liver accumulation, and preferential uptake by the immune system. In this sense, the analyses of the protein corona performed along this work will hopefully contribute to advancing a new generation of rationally designed nanometric drug delivery systems. [ABSTRACT FROM AUTHOR]

This article presents an efficient and effective design approach of the phase distribution calculation across metasurface for significant radar cross section (RCS) reduction of a circular polarization (CP) and liner polarization (LP) radar waves. The RCS reduction using the proposed design approach is achieved by imposing a novel cusp phase mask (which is usually used to generate 3D self-accelerating and self-healing cusp beams) at each geometric phased anisotropic unit cell composing the proposed cusp phased metasurface. By solving the cusp phase formula using MATLAB, it is found that the cusp phase mask required to achieve more than 10 dB of RCS reduction over a wide frequency band can be calculated without the need of significant lengthy optimizations or huge computer resources. The ability of such cusp phase mask metasurfaces to achieve significant backward scattering and RCS reduction has been rigorously investigated by means of simulations and measurements. When illuminated by a far-field radar CP or LP plane wave, the proposed cusp phased metasurface realizes more than 10 dB of RCS reduction from 10.9 to 26 GHz, corresponding to a fractional bandwidth of FBW = 81.8%. The 10 dB RCS reduction bandwidth of the cusp metasurface is maintained under both normal and wide angular incidence up to 75o. The proposed cusp metasurfaces have potential applications to make objects stealthy where the incidence radar signal has an unknown frequency, polarization, or angle of incidence.

Electromagnetic metamaterial is an artificial composite composed of periodic subwavelength microstructure，which has a strong conduction regulation or absorption effect on electromagnetic wave，and it has been widely studied in the field of stealth design of aviation weapons and equipment. In this paper，the concept of electromagnetic metamaterial is introduced firstly，and the latest research progresses of electromagnetic control metamaterial，electromagnetic absorbing metamaterial，active tunable metamaterial and intelligent metamaterial are reviewed. Then，the stealth mechanism and the application research status of electromagnetic deflection metamaterial，electromagnetic absorbing metamaterial and frequency selective metamaterial are introduced. It is analyzed that the rich stealth mechanism and the strong designability are the main advantages of electromagnetic metamaterials as distinct from the traditional absorbing materials. For the development of electromagnetic metamaterial，this paper puts forward three suggestions from expanding the absorbing spectrum，enhancing the absorbing performance，and smart tunable of absorbing ability，specifically including the expansion of absorbing spectrum to infrared，laser and ultraviolet band，further improving the broadband absorbing ability，and intelligent adjusting the absorbing frequency band.

Target drone construction planning should closely follow the development trend of future air threats, focus on the characteristics of future typical threat targets and combat modes, and realize realistic simulation. Aiming at the future air threats such as the next generation fighter planes and unmanned cooperative combat aircraft in the United States and Europe, the development direction and typical characteristics of the new generation target drone system are analyzed and studied. Based on the requirements of future firing test tasks, some new viewpoints are put forward, such as the simulation object of target drone will be extended to the field of unmanned aerial vehicles, and the application of firing test will tend to be cooperative formation for target. According to the requirements of the future firing test tasks, the key capabilities of the new generation target drone system are explored.

The use of traditional optimization methods in engineering design problems, specifically in aerodynamic and infrared stealth optimization for engine nozzles, requires a large number of objective function evaluations, therefore introducing a considerable challenge in terms of time constraints. In this paper, this limitation is addressed by using a sample-efficient multi-objective Bayesian optimization that takes Kriging as a surrogate model and Expected Hypervolume Improvement as the infill criterion. Using this approach, the probabilistic model is continuously established and updated, and the approximate Pareto front is obtained at a relatively small computational budget. The objective of this work is to evaluate the applicability of employing a multi-objective Bayesian optimization framework for the aerodynamic-infrared shape optimization of an elliptical double serpentine nozzle at 6 km flight condition, where the objective functions are evaluated by means of high-fidelity computational fluid dynamics and reversed Monte Carlo ray tracing simulations. We achieve good results in both infrared radiation signature reduction and aerodynamic performance improvement with a reasonable number of evaluations, indicating that the proposed method is effective and efficient for tackling the computationally intensive optimization challenges in the aircraft design. [ABSTRACT FROM AUTHOR]

The cockpit is one of the important scattering sources for conventional fighters in their nose direction. In order to study its scattering characteristics, the analysis method of influence of cockpit stealth measure on electromagnetic scattering was proposed. And the electromagnetic models of fighters with conventional and stealth cockpit were established based on a fighter. The RCS (Radar Cross Section) values in various states were calculated by Physical Optics(PO) method. The distribution characteristics of RCS curves and the response characteristics of electromagnetic scattering on pitch angle and frequency were analyzed. The results show that the cockpit stealth measures significantly reduce cavity scattering in nose direction, so that the peak of scattering curves in nose direction disappears and the curves converge inward. Besides, when the pitch angle is within a certain range, the RCS mean value with stealth cockpit in nose direction is about -20 dBsm (which incident frequency is 6 GHz), and the curves of relative reduction value is distributed in “W” shape with the variation of pitch angle, and the maximum value is 19.7887 dB when the pitch angle is 0 degrees. When the frequency increases, the RCS mean value in nose direction decreases gradually, while the relative reduction values change fluctuatly, and the maximum value is up to 24.6674 dB. And in the remaining angular domains, the response characteristics with pitch angle and multi-frequency are relative weak; and the conventional fighters’ stealth performance with different pitch angles and multi-frequency in the nose direction of angular domain can be improved by the stealth measures of cockpit. [ABSTRACT FROM AUTHOR]

The terahertz frequency range is gaining popularity in security, stealth technology, and the future 6G network communication. For the control of severe terahertz electromagnetic interference (EMI) pollution, frequency‐selective stealth‐capable shielding materials are being explored to mask terahertz signals. For the realization of masking terahertz signals, the robustness, lightweight, and shape‐conformable materials with excellent terahertz EMI shielding/absorption are crucial. Here, the study reports the fabrication of 3D symmetric pyramidal architectural MXene composite films with frequency‐selective stealth performance characteristics via the facile drop casting method. With the high absorption capability of 2D MXene layers, the MXene composite films exhibit substantial terahertz stealth performance. 3D pyramidal microstructure design leads to frequency selective surface‐assisted reflection resonance in the frequency range of 0.6–1.1 THz. The MXene composite film demonstrates an outstanding maximum terahertz shielding effectiveness (SE) of up to 70.4 dB and a specific SE of 0.55 dB µm−1. These terahertz SE values exceed all of those for MX‐based shielding material designs reported in the literature. The investigation will open a new direction toward developing terahertz EMI shielding thin films with easy integration into any surface for stealth capabilities. [ABSTRACT FROM AUTHOR]

Opsonization plays a pivotal role in hindering controlled drug release from nanoformulations due to macrophage‐mediated nanoparticle destruction. While first and second‐generation delivery systems, such as lipoplexes (50–150 nm) and quantum dots, hold immense potential in revolutionizing disease treatment through spatiotemporal controlled drug delivery, their therapeutic efficacy is restricted by the selective labeling of nanoparticles for uptake by reticuloendothelial system and mononuclear phagocyte system via various molecular forces, such as electrostatic, hydrophobic, and van der Waals bonds. This review article presents novel insights into surface‐modification techniques utilizing macromolecule‐mediated approaches, including PEGylation, di‐block copolymerization, and multi‐block polymerization. These techniques induce stealth properties by generating steric forces to repel micromolecular‐opsonins, such as fibrinogen, thereby mitigating opsonization effects. Moreover, advanced biological methods, like cellular hitchhiking and dysopsonic protein adsorption, are highlighted for their potential to induce biological camouflage by adsorbing onto the nanoparticulate surface, leading to immune escape. These significant findings pave the way for the development of long‐circulating next‐generation nanoplatforms capable of delivering superior therapy to patients. Future integration of artificial intelligence‐based algorithms, integrated with nanoparticle properties such as shape, size, and surface chemistry, can aid in elucidating nanoparticulate‐surface morphology and predicting interactions with the immune system, providing valuable insights into the probable path of opsonization. Significance statement: This review article meticulously compiles an extensive body of knowledge, encompassing state‐of‐the‐art surface modification techniques and innovative biological camouflage strategies. These insights collectively propel the progression of next‐generation drug delivery platforms. By elucidating the underlying mechanisms, detailing achievements, and recognizing inherent limitations of these methodologies, the article provides essential guidance to researchers, clinicians, and pharmaceutical developers, facilitating well‐informed decision‐making. Moreover, the incorporation of empirical data pertaining to clinical trials, patent landscape, and commercially available formulations augments the pragmatic utility of this review. It emerges as an indispensable resource for those endeavoring to bridge the chasm between scientific innovation and tangible therapeutic outcomes. In conclusion, this review signifies a transformative contribution poised to reshape the landscape of drug delivery, holding promising prospects for substantial enhancements in patient outcomes in the immediate future. [ABSTRACT FROM AUTHOR]

Copyright of Aero Weaponry is the property of Aero Weaponry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modern fighter aircraft increasingly need to conjugate aerodynamic performance and low observability. In this paper, we showcase a methodology for a gradient-based bidisciplinary aero-stealth optimization. The shape of the aircraft is parameterized with the help of a CAD modeler, and we optimize it with the SLSQP algorithm. The drag, computed with the help of a RANS method, is used as the aerodynamic criterion. For the stealth criterion, a function is derived from the radar cross-section in a given cone of directions and weighed with a function whose goal is to cancel the electromagnetic intensity in a given direction. Stealth is achieved passively by scattering back the electromagnetic energy away from the radar antenna, and no energy is absorbed by the aircraft, which is considered as a perfect conductor. A Pareto front is identified by varying the weights of the aerodynamic and stealth criteria. The Pareto front allows for an easy identification of the CAD model corresponding to a chosen aero-stealth trade-off.

Abstract The terahertz frequency range is gaining popularity in security, stealth technology, and the future 6G network communication. For the control of severe terahertz electromagnetic interference (EMI) pollution, frequency‐selective stealth‐capable shielding materials are being explored to mask terahertz signals. For the realization of masking terahertz signals, the robustness, lightweight, and shape‐conformable materials with excellent terahertz EMI shielding/absorption are crucial. Here, the study reports the fabrication of 3D symmetric pyramidal architectural MXene composite films with frequency‐selective stealth performance characteristics via the facile drop casting method. With the high absorption capability of 2D MXene layers, the MXene composite films exhibit substantial terahertz stealth performance. 3D pyramidal microstructure design leads to frequency selective surface‐assisted reflection resonance in the frequency range of 0.6–1.1 THz. The MXene composite film demonstrates an outstanding maximum terahertz shielding effectiveness (SE) of up to 70.4 dB and a specific SE of 0.55 dB µm−1. These terahertz SE values exceed all of those for MX‐based shielding material designs reported in the literature. The investigation will open a new direction toward developing terahertz EMI shielding thin films with easy integration into any surface for stealth capabilities.

Copyright of Journal of Aeronautical Materials is the property of Editorial Board of Journal of Aeronautical Materials and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The aim of the present study is the development, physicochemical characterization, and in vitro cytotoxicity evaluation of both empty and quercetin-loaded HSPC (hydrogenated soy phosphatidylcholine) liposomes, GMO (glyceryl monooleate) liquid crystalline nanoparticles, and PHYT (phytantriol) liquid crystalline nanoparticles. Specifically, HSPC phospholipids were mixed with different non-ionic surfactant molecules (Tween 80 and/or Span 80) for liposomal formulations, whereas both GMO and PHYT lipids were mixed with Span 80 and Tween 80 as alternative stabilizers, as well as with Poloxamer P407 in different ratios for liquid crystalline formulations. Subsequently, their physicochemical properties, such as size, size distribution, and ζ-potential were assessed by the dynamic and electrophoretic light scattering (DLS/ELS) techniques in both aqueous and biological medium with serum proteins. The in vitro biological evaluation of the empty nanosystems was performed by using the MTT cell viability and proliferation assay. Finally, the entrapment efficiency of quercetin was calculated and the differences between the two different categories of lipidic nanoparticles were highlighted. According to the results, the incorporation of the non-ionic surfactants yields a successful stabilization and physicochemical stability of both liposomal and liquid crystalline nanoparticles. Moreover, in combination with an appropriate biosafety in vitro profile, increased encapsulation efficiency of quercetin was achieved. Overall, the addition of surfactants improved the nanosystem's stealth properties. In conclusion, the results indicate that the physicochemical properties were strictly affected by the formulation parameters, such as the type of surfactant. [ABSTRACT FROM AUTHOR]

The objective of the present work was to study the effect of varied weight percentages of chopped carbon fiber (CCF) as functional material in glass fabric-reinforced plastic (GFRP) composites. The electromagnetic and mechanical properties of these functional composites were analyzed to explore the potential applications in the aerospace/defense industry as a stealth solution. Developed composites were mechanically tested with variable crosshead speed (1–3 mm/min.). These composites showed degradation in tensile strength with enhancement in the concentration of CCF. However, flexural strength and interlaminar shear strength decreased initially and then increased. GFRP composite with 0.1 weight % of CCF loading showed electromagnetic absorption of 16.3 dB at 9.20 GHz (X-band). Microstructural analysis was conducted using FESEM which also supports the mechanical behavior of composites. Taguchi method was applied to optimize the process parameters of crosshead speed and loading of functional material. [ABSTRACT FROM AUTHOR]

Demand for the development of the convergence industry, research studies on heat transfer, thermal characteristics, semiconductors, motors, and batteries using special materials have come to the fore. Meanwhile, molybdenum (Mo) exhibits relatively small inorganic qualities, and the thermal conductivity rate is applied to various fields. In this study, in-depth characteristics were considered regarding the concentration of thermal characteristics and IR characteristics. In particular, this study conducted a thicker molybdenum layer sputtering work than previous studies and examined it in detail at high temperatures by pore size. This study calculated each phase temperature of the molybdenum-sputtered specimens in the steady state according to the heat transfer theory. When the molybdenum-sputtered fabric's metal layer pointed to the outside air, the heat transfer rate (Q) was high at 5748.3 W. In contrast, if the molybdenum-sputtered film's metal layer pointed toward the heat source, the heat transfer rate (Q) was low at 187.1 W. As a result of measuring the IR transmittance, the infrared transmittance of the molybdenum-sputtering-treated sample was significantly reduced compared to the untreated sample. It is believed that the molybdenum-sputtering polyamide samples produced in this study can be applied to multifunctional military wear, biosignal detection sensors, semiconductor products, batteries, etc., by utilizing excellent electrical properties, stealth functions, and IR-blocking properties. [ABSTRACT FROM AUTHOR]

A Minkowski-inspired circular fractal microwave absorber has been presented, operable at multibands between 1 to 18 GHz. The proposed absorbing structure is constituted with novel geometry of second-order circular fractal rings impinged on a dielectric substrate backed by a metallic layer. The ability of miniaturization offered by a unique Minkowski circular fractal geometry has been exploited for the unit cell designing of a multiband absorber with a smaller dimension. The nearly perfect absorption of multiple peaks is persistent with polarization variation, and the impact of variation in the angle of incidence under transverse electric (TE) and transverse magnetic (TM) modes was also elucidated. The electric-field distribution and surface-current density at the resonating frequencies have been studied to better understand the absorption mechanism. The designed absorbing structure has been fabricated and a free-space microwave measurement setup has been used to measure it. The good miniaturization capabilities, strong absorption at multibands, insensitivity to polarization angle variation, and good angular stability qualify the proposed absorber for scientific and military applications. [ABSTRACT FROM AUTHOR]

Aiming at the discharge problem of inductively coupled plasma (ICP), a closed wave-transmitting cavi-ty configuration is designed, the fluid mechanics model of ICP is established, and the multi physical simulation software COMSOL is used for three-dimensional simulation research. The variation laws of typical parameters such as electron density, electron temperature and plasma potential with time in the discharge process are analyzed. On this basis, the power of radio frequency power supply, the air pressure in the cavity and other conditions are changed to obtain the parameter range and spatial gradient distribution of ICP. The results show that the discharge power mainly affects the numerical range of plasma parameters, and the change of air pressure has an effect on the numerical value and spatial distribution of plasma parameters. When the power of radio frequency power supply increases from 100 W to 300 W, the peak electron density increases from 2.54×1017 m-3 to 5.68×1017 m-3, and the electric potential induced in the heating zone and the corresponding electron temperature decrease slightly after the reaction is stable. Increasing the air pressure in the cavity within a certain range will significantly increase the electron density. The air pressure increases from 10 Pa to 30 Pa, and the electron density increases from 9.12×1017 m-3 to 3.62×1018 m-3. However, the uniformity of plasma parameter distribution will deteriorate if the air pressure is too high.

The use of traditional optimization methods in engineering design problems, specifically in aerodynamic and infrared stealth optimization for engine nozzles, requires a large number of objective function evaluations, therefore introducing a considerable challenge in terms of time constraints. In this paper, this limitation is addressed by using a sample-efficient multi-objective Bayesian optimization that takes Kriging as a surrogate model and Expected Hypervolume Improvement as the infill criterion. Using this approach, the probabilistic model is continuously established and updated, and the approximate Pareto front is obtained at a relatively small computational budget. The objective of this work is to evaluate the applicability of employing a multi-objective Bayesian optimization framework for the aerodynamic-infrared shape optimization of an elliptical double serpentine nozzle at 6 km flight condition, where the objective functions are evaluated by means of high-fidelity computational fluid dynamics and reversed Monte Carlo ray tracing simulations. We achieve good results in both infrared radiation signature reduction and aerodynamic performance improvement with a reasonable number of evaluations, indicating that the proposed method is effective and efficient for tackling the computationally intensive optimization challenges in the aircraft design.

Transgender people, being stigmatized, discriminated against, abused, and having less access to social, health, and public health services appear to be a hard-to-reach group for researchers. Thus, with very few opportunities for research, especially representative ones, it is challenging to plan high-quality and effective interventions that would help overcome stigma and discrimination as well as prevent violence against this group. The methods used to recruit respondents from hard-to-reach groups to assume that less visible subgroups can be accessed through the available, more visible ones. Still, the data presented in this article indicate the incoherence of social networks of trans- and non-binary people due to the stigma and discrimination. The main empirical findings aimed to describe the instability of the social ties within a group of transgender and non-binary people, probable explanations for the causes of this instability, and the main lines of the community fragmentation. Personal traumatic experiences of transgender people and the dispersion of the community also affect its weak involvement in civic activities. The paper dwells upon a phenomenon that is argotically called “stealth”: a transgender person in a particular time, having achieved the desired result in transgender transition, distances themself from the community, striving to live an everyday life in society in a new gender. Accordingly, such people lose all or most of their social ties with other transgender and/or non-binary people and are inaccessible both to the research aimed at this specific group and to various social programs. Based on the material used in this article, we can discuss the lack of a single community of transgender and non-binary people in Ukraine and the need to use this term about transgender and non-binary people in the plural, not singular, because each subgroup of trans- and non-binary people, is a separate community. At the same time, the existing forms of stable connections are described, such as public organizations, networks of fictitious kinship, etc. This article will be helpful for researchers, as well as project managers whose attention is focused on transgender and non-binary people in Ukraine.

The canopy of a fighter is the main source of electromagnetic scattering, and the achievement of its radar stealth is one of key technologies for developing a stealth fighter. The scattering sources mainly include the scattering in the cavity of the canopy (strong scattering source) and the local structural scattering (sub-strong scattering source). To satisfy the high stealth requirements, it is necessary to reduce the RCS of the sub-strong scattering source of the canopy. This paper studies the sub-strong scattering source of the canopy of a stealth fighter and proposes the canopy's sub-strong scattering source reduction and control measure by applying the basic radar stealth technology, the MLFMM and the RCS test.

Implementation of stealth features on advanced airborne platforms (aircrafts, unmanned air vehicles, missiles, etc.) has become a compulsion for each country, for denial/delay detection of these objects from enemy radars, during tactical missions. Apart from the shaping of the airframe, implementation of microwave-absorbing materials (MAMs) on identified locations of airborne vehicles is the only viable solution to reduce their radar cross-section (RCS) and eventually attain stealth capabilities. Numerous dielectric and magnetic class materials have been developed over the last few decades to fulfil the requirement for RCS reduction against various radars operating in different frequency ranges. In this review, a detailed representation of almost the entire range of materials used as MAMs has been provided along with their possible microwave (MW) loss mechanism to fill the gap that existed for a systematic insight on MAMs till now. The current limitations and future aspects are also discussed for the development of future stealth materials. [ABSTRACT FROM AUTHOR]

Tracking military structures and equipment is one of the parameters to create superiority in military battles. Camouflage has long been used to reduce the possibility of detection of military structures and equipment. Development of knowledge in the field of tracking and discovering military structures and equipment followed by the necessity of using the concealment in order to reduce vulnerability in war, has enhanced the importance of using new camouflage and radar evasion methods. The use of nanotechnology in the field of radar evasion of military facilities was developed by introducing graphene as a very strong absorber of electromagnetic waves. Graphene coating on the military installations causes the absorption of electromagnetic waves and as a result, these installations are not detected by the enemy's radar. Referring to the fact that there is a functional relationship between the diameter of the graphene oxide used and the radar evasion of the equipment, an attempt has been made in this article for the first time to find a solution to control and monitor the radar evasion quality using graphene oxide (with the scientific name of RGO/NiFe2O4) in the microwave spectrum of 7GHZ by the profile approach and presentation of a regression relationship. This model can be used to monitor the quality of radar evasion products (cheaper and faster than existing methods). Finally, sensitivity analysis of the model showed that the ability to detect non-conformity in the manufactured products can be detected quickly (between 1 and 20 samples) with the change in the parameters of the regression model. [ABSTRACT FROM AUTHOR]

In order to reduce the infrared emissivity to meet the requirements of modern warfare for infrared stealth materials, we prepared the polymers containing Schiff base moieties using polyetheramine and 2,6-pyridinedicarboxaldehyde by solution polycondensation and coordinated with Ni2+, Cu2+, and Sm3+ ions to prepare organic coatings. The structure and the thermal and mechanical properties of the coatings were studied in detail. Meanwhile, the effect of the conductivity change of coordination polymers on infrared emissivity was studied systematically. The results showed the polymer coordinated with Sm3+ ions had the lowest energy band gap, which was 2.99 eV, and the best electrical conductivity of 3.54 × 10−4 S/cm compared with Ni2+ and Cu2+ coordination polymers. The infrared emissivity was the lowest in the 2–22 μm infrared waveband range, which reached 0.58, suggesting the polymers containing Schiff base moieties and their coordination polymers may have a great potential to be applied as infrared stealth materials in military applications. [ABSTRACT FROM AUTHOR]

Nanoparticles (Nps) have revolutionized the landscape of many treatments, by modifying not only pharmacokinetic properties of the encapsulated agent, but also providing a significant protection of the drug from non-desired interactions, and reducing side-effects of the enclosed therapeutic, enabling co-encapsulation of possibly synergistic compounds or activities, allowing a controlled release of content and improving the therapeutic effect. Nevertheless, in systemic circulation, Nps suffer a rapid removal by opsonisation and the action of Mononuclear phagocyte system (MPS). To overcome this problem, different polymers, in particular Polyethyleneglycol (PEG), have been used to cover the surface of these nanocarriers forming a hydrophilic layer that allows the delay of the removal. These advantages contrast with some drawbacks such as the difficulty to interact with cell membranes and the development of immunological reactions, conforming the known, "PEG dilemma". To address and minimize this phenomenon, different strategies have been applied. Therefore, this review aims to summarize the state of the art of Pegylation strategies, comment in depth on the principal characteristics of PEG and describe the main alternatives, which are the use of cleavable PEG, addition of different polymers or even use other derivatives of cell membranes to camouflage Nps. [Display omitted] [ABSTRACT FROM AUTHOR]

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After intravenous administration of nanocarriers, plasma proteins may rapidly adsorb onto their surfaces. This process hampers the prediction of the nanocarriers' pharmacokinetics as it determines their physiological identity in a complex biological environment. Toward clinical translation it is therefore an essential prerequisite to investigate the nanocarriers' interaction with plasma proteins. Here, this work evaluates a highly "PEGylated" squaric ester‐based nanogel with inherent prolonged blood circulation properties. After incubation with human blood plasma, the nanogels are isolated by asymmetrical flow‐field flow fractionation. Multiangle light scattering measurements confirm the absence of significant size increases as well as aggregation upon plasma incubation. However, proteomic analyses by gel electrophoresis find minor absolute amounts of proteins (3 wt%), whereas label‐free liquid chromatography mass spectrometry identify 65 enriched proteins. Interestingly, the relative abundance of these proteins is almost similar to their proportion in pure native plasma. Due to the nanogels' hydrated and porous network morphology, it is concluded that the detected proteins rather result from passive diffusion into the nanogel network than from specific interactions at the plasma particle interface. Consequently, these results do not indicate a classical surface protein corona but rather reflect the highly outer and inner stealth‐like behavior of the porous hydrogel network. [ABSTRACT FROM AUTHOR]