Compensation Layer Research Articles

RF-Transparent Radome with Compensation Layer for Reducing Boresight Error

RF-Transparent Radome with Compensation Layer for Reducing Boresight Error

EXPERIMENTAL TESTING OF PLUNGER RECOVERY MODES BY COMBINED PROCESSING

Stainless steel parts are widely used in milk processing equipment. The condition of these elements determines the operability of the equipment and the quality of the product. The most susceptible to wear are parts of the plunger type, the failure of which is by the loss of the cylindricity when changing geometric dimensions in longitudinal and cross sections. (Research purpose) The research purpose is developing a method for restoring cylindrical parts of the plunger type during combined processing; reducing the complexity of the restoration process and increasing the durability of the plunger (Materials and methods) Samples of 40Kh13 steel imitating the shape of a plunger with a diameter of 45 millimeters were studied. Three samples were produced with different pre-treatment: shot blasting, finishing turning and manual grinding. The study was as follow: initial measurement of the diameter in four sections at three levels; electric spark buildup, electromechanical processing and grinding before the preparing the working surface; measuring geometric parameters before and after each treatment; making slits for microstructural analysis, and measuring microhardness. (Results and discussion) As a result of the experiment and sample processing, there achieved an increase in diameter by 1.10 ± 0.08 millimeters when applying from 15 to 20 layers by the electric spark method with an electrode of the brand 308L-16. After deformation during electromechanical processing, the layer ranged from 0.36 ± 0.03 to 0.47± 0.07 millimeters, during grinding, the thickness of the final layer was from 0.04 ± 0.02 to 0.26± 0.02 millimeters. Measurements of the microhardness of the structural zones showed that the microhardness of the residual layer is 250-400 Vickers, the transition zone has a compacted structure and a hardness of over 550, and the core is 200-250. (Conclusions) Based on these data, the article proposes recommendations for the building of a compensation layer to restore the cylindrical working surface of the plunger type part.

Wide viewing angle polarization interference filter using double liquid crystal layers with opposite twisted direction.

We demonstrate a wide viewing angle polarization interference filter (PIF), which consists of two crossed polarizers and double liquid crystal layers with opposite twisted direction. The polarization interference effect of the PIF is achieved by the double liquid crystal layers, and an additional compensation layer between the double liquid crystal layers can further improve the optical performance of the PIF. By using the Jones matrix method, we derive the transmittance formula of the PIF with/without compensation layer, which can be used to design any required color filter by selecting the appropriate twist angle and thickness of the liquid crystal layer. We design blue, green and red PIFs and analyze their optical performance. The proposed PIF has a wider viewing angle (±30°), and the color saturation of the PIF is also considerably high.

Prediction of safety parameters of pressurized water reactor based on feature fusion neural network

Rapid and accurate calculation of safety parameters based on the state and layout of the core is essential to ensure the safe operation of nuclear reactors. Based on artificial intelligence technology, we established a neural network model with seven layers, called the feature fusion neural network (FFNN). A residual compensation layer is added in the third hidden layer to avoid gradient dispersion, and a feature fusion layer is added in the last hidden layer to fuse low-dimensional features and high-dimensional features. Numerical experiments simulate the pressurized water reactor of Qinshan Nuclear Power Station, and 10,000 sets of safety parameters are calculated by CASMO5 under different arrangements as ground truth. Experiments show that the mean relative error of the subassembly power peaking factor and rod power peaking factor estimated by FFNN is about 1%, and the maximum relative error of the limited effective multiplication factor is within 0.5%.

A method of dynamic union control for intelligent mould bed system in ship block building

ABSTRACT Mould bed is the most important equipment to control the deformation in the process of block construction. However, its height needs to be controlled separately based on the known height, and it affects the construction precision of block severely. Therefore, a dynamic union control method is proposed in this paper. Firstly, in order to realize the union control of mould bed system, the distribution types of mould bed system are defined, and a dynamic relationship is established, the determination algorithm number, position and height compensation layer number is proposed. Secondly, the fuzzy PID control based on neural network is used to realize the adaptive control of height according to the changes of pressure, so as to control the construction quality better of block. Thirdly, the MATLAB/Simulink module is used to verify the proposed method and shows that the response time is significantly shortened by 41% and 37.5% respectively.

A Conformal Metamaterial-Based Optically Transparent Microwave Absorber With High Angular Stability

We put forward an optically transparent microwave absorber based on a conformal broadband metamaterial, which shows high angular stability. Our absorber is a double-layer sandwich structure mainly made of transparent polyvinyl chloride sheets and indium tin oxide films. To achieve wideband absorption and high angular stability, an impedance layer composed of square spiral elements is exploited to increase the absorption bandwidth. A compensation layer is then employed to address the mismatch between the impedance of the absorber and that of free space at high angular incidences. Experimental results show that a high light transmittance (69.4%), together with an adequate absorption bandwidth (85.7%) and angular stability (60°) may be achieved with planar and conformal configurations, including different curvatures.

Charging Compensation Layer on Polyimide for Enhanced Device Stability in Flexible Technology

In this paper, we propose a structure that prevents the charging effects that occur in devices fabricated on polyimide (PI) substrates. In general, when fabricating a device on a PI substrate, an inorganic barrier layer is first deposited to prevent penetration of oxygen and moisture. In this study, we confirmed that fluorine ions were induced from PI by bias stress and proposed a SiOCH/SiO2 double layer as a barrier to prevent charging. Then, Al/PI/SiO2/Al and Al/ PI/SiOCH/SiO2/Al metal–insulator–metal capacitors were manufactured. The capacitor characteristics before and after application of bias stress were verified through current–voltage (I–V) and capacitance–voltage (C–V), which are electrical characterization methods, and secondary ion mass spectrometry (SIMS), which is a physical analysis method. As the voltage increased, the capacitance and current of the Al/PI/SiO2/Al capacitor varied, but those of the Al/PI/SiOCH/SiO2/Al device did not change. Finally, SIMS analysis confirmed that the PI-derived fluorine ions replaced the Si–CH3 bonds within the SiOCH film with Si–F bonds, thereby preventing capacitance and current fluctuations.

Origin of leakage current in vertical GaN devices with nonplanar regrown p-GaN

This work demonstrates large-area vertical GaN-on-GaN Schottky barrier diodes (SBDs) with different p-GaN terminations fabricated by the p-GaN regrowth on planar and nonplanar n-GaN structures and studies the leakage current in these regrown p-GaN terminations. The SBDs with planar p-GaN terminations demonstrate a higher breakdown voltage than the non-terminated SBDs. In contrast, the SBDs with nonplanar regrown terminations exhibit a significantly higher leakage current, which agrees with the tunneling behavior. The microscopic current mapping and local current–voltage (I–V) spectra are acquired using conductive atomic force microscopy (C-AFM) in the nonplanar regrown junction region. The local leakage currents and conduction types are derived from the I–V characteristics of the Schottky barrier between the metalized C-AFM tip and GaN. The dominant leakage path is revealed to be the tunneling across the Schottky barrier to the regrowth sidewall assisted by high-concentration interfacial impurities, followed by current flow along the regrowth sidewall. An ∼0.7 μm-wide n-type compensation layer is found next to the non-polar regrowth sidewall, which does not directly induce a major leakage path but moves the p-GaN away from the regrowth interface, thus weakening the p-GaN depletion of the sidewall interfacial impurities as well as facilitating the formation of a crowded electric field and tunneling at the Schottky contact to the regrowth region.

Improved Deep Trench Super-junction LDMOS Breakdown Voltage By Shielded Silicon-Insulator-Silicon Capacitor

Deep trench LDMOS is widely used in high-voltage level power devices. This paper proposes and optimizes a deep trench super-junction LDMOS with triangular charge compensation layer (TCCL DT SJ LDMOS), which solves the problem of charge imbalance in the super-junction region due to the Silicon-Insulator-Silicon (SIS) capacitance at both ends of the trench and improves the Breakdown Voltage (BV) of the device. This structure also helps to deplete the drift region at the bottom of the deep trench by adding P-buffer under the N-Pillars, which improves the doping concentration and reduces the specific on-resistance of the device. The simulation results show that compared with the Con. DT SJ LDMOS, the BV of the TCCL DT SJ LDMOS has been increased from 498V to 730V, and the power figure of merit (FOM) has increased by 12.8 MW / cm2(FOM = BV2 / Ron, sp).

Temperature Compensation of an Air-Filled Stacked Ring Resonator

A temperature-compensated resonator based on stacked rings is proposed in this letter. The resonator is made of several layers of machined dielectric substrates where the copper rings stand. These rings define an air-filled TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> cavity with an unloaded quality factor better than 1800. Due to a low sensitivity of the air gap between the layers and metallic contact of the TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> mode, a cavity with low building constraints (no vias and no connection between layers) is realized. Furthermore, a multilayer design allows the introduction of a controlled amount of dielectric material in the cavity with a negative thermal coefficient of permittivity to realize temperature compensation of the device and to counteract its natural thermal expansion. Thus, this compensation layer allows proper management of a frequency drift from of -18 to +18 MHz for a temperature range of 20 °C-80 °C. However, there is a tradeoff, and the quality factor decreases as the compensated layer is inserted. A guideline demonstrating the performance of the design and the compensation technique is thus presented in this letter.

Zero-Balance Method for Evaluation of Sealed Cavity Pressure Down to Single Digit Pa Using Thin Silicon Diaphragm

The sealed cavity pressure of a micro-package often becomes the determining factor of the performance of an encapsulated micro-electro mechanical system (MEMS). In this study, a sealed cavity pressure evaluation method for a micro-package using a thin diaphragm is studied comprehensively. The sealed cavity pressure is identical to the surrounding pressure when the diaphragm separating both volumes becomes flat, i.e. zero-balance method. The zero-balance method has advantages to other techniques in terms of fabrication process simplicity and pressure evaluation range. Two approaches are introduced to reduce the impact of the residual stress, which typically exists in the conventionally used silicon-on-insulator (SOI) diaphragm. The introduction of a stress compensation layer was able to reduce the impact of the residual stress of SOI-based diaphragms. However, a significant hysteresis is developed on the diaphragm, which limits the precise measurement of a sealed cavity. On the other hand the residual stress can be avoided by the usage of intentionally tensile stressed boron doped Si diaphragm, which is produced by alkaline wet etching. Using such a diaphragm, a sealed cavity pressure of several Pa can be measured with a single digit Pa accuracy. [2020-0014]

BGaAs strain compensation layer in novel BGaAs/InGaAs/BGaAs heterostructure: Exceptional tunability

We investigate a novel grown-MOCVD BGaAs/InGaAs/BGaAs/GaAs heterostructure for the first time using High-Resolution X-Ray Diffraction (HR-XRD), steady state photoluminescence (PL) and time-resolved photoluminescence (TRPL). The strain effects in the InGaAs/GaAs quantum well is compensated due to the additional BGaAs buffer/barrier layer (%B = 7.8%). PL measurements show an extended emission around 1 eV and two emission bands associated with the InGaAs and BGaAs layers and these bands are analyzed theoretically with the help of 10 band k‧p Hamiltonian. Red shifts of about 0.15 eV (InGaAs) and 0.29 eV (BGaAs) are observed, encouraging dual applications in high wavelengths and solar cells. A reduction of the abnormal behavior due to potential fluctuations and carrier localization is quantitatively and qualitatively investigated using the Localized States Exciton model (LSE) model. Our structure appears to be a promising candidate for future-generation ultra high-efficiency three- and four-junction multijunction solar cell devices as well as its applications in the telecommunication wavelength range.

Conformal doping strategy for fin structures: tailoring of dopant profile through multiple monolayer doping and capping layer control

Monolayer doping (MLD) has attracted attention as a next-generation doping method because of its great potential for conformal doping of non-planar nanostructures. However, fundamental limitations are identified in conformal doping of fin structures using conventional MLD process, and fin structures doped with conventional MLD presents a poor dose conformality (surface concentration ratio between the side-wall and the top of the fin) of 0.32. The poor dose conformality is mainly caused by the hydrogen-terminated silicon surface formed differently depending on the orientation of each face of the fin structure and the capping layer deposited with low step coverage on the fin structure. As a strategy to overcome the limitations without increasing process complexity, multiple-MLD for dose compensation and capping layer thickness control for adjusting the dopant diffusivity are proposed. These methods are found to be effective in tailoring doping profiles on each face of the fin structure with a fine dose controllability from about 70% to 200%. Finally, it is demonstrated that the proposed approach allows conformal doping of the fin structure with a high surface concentration of 5 × 1020 atoms cm−3 and an excellent dose conformality of 0.98.

Anti-guiding and guiding effects in GaN-based vertical-cavity surface-emitting lasers

We study the lateral optical confinement effect on the performance and lasing characteristics of GaN-based vertical-cavity surface-emitting lasers (VCSELs). The anti-guiding and guiding structures are designed by calculating the effective refractive index difference of active and cladding regions. By varying the compensation layer configuration and thickness, the designed effective refractive index of the active region is 0.44% higher than peripheral for the guiding structure. The threshold current density of VCSEL with the guiding structure is 25.4 kA/cm2, which is almost half of that with the anti-guiding structure showing 53.5 kA/cm2. For the anti-guiding structure, the signals from both active and cladding regions are observed by the far-field angle-resolved spectrum at 1.4 × Ith driving current, which agrees well with our simulation. Throughout the study, we show the advantage of the guiding structure both theoretically and experimentally. Moreover, an effective guiding structure is obtained by a proper design and simple device process, which will be very promising for mass production.

Improved strength and ductility of friction stir tailor-welded blanks of base metal AA2024 reinforced with interlayer strip of AA7075

Most of welded parts requires secondary forming process to meet the design requirements which makes the ductility of the joint an important parameter to be improved. To this end, we imped compensation layer of AA7075 aluminum alloy between two blanks of AA2024 aluminum alloy during friction stir welding. The effect of compensation layer width on the microstructure, microhardness, tensile strength and failure strain was investigated. XRD results showed that using AA7075 alloy compensation layer helped for precipitation of new intermetallic phases, Al2Cu and Mg2Zn, at the grain boundaries of Al grains. Tensile test results showed that the sample with 2 mm width compensation layer possess 18% improved strength and 54.4% improved failure strain compared with the joint without compensation layer. The failure strain of this joint was 16.8% which is almost that for AA2024 (17.2%). The improved strength was because of the grain refinement and the precipitation of Al2Cu and Mg2Zn intermetallics. While the improved failure strain was due to the higher content of Mg and Zn alloying elements in AA7075 alloy which precipitate on the grain boundaries facilitating the slipping between grains and provide more deformability of the global structure.

MDFC–ResNet: An Agricultural IoT System to Accurately Recognize Crop Diseases

Crop disease diagnosis is an essential step in crop disease treatment and is a hot issue in agricultural research. However, in agricultural production, identifying only coarse-grained diseases of crops is insufficient because treatment methods are different in different grades of even the same disease. Inappropriate treatments are not only ineffective in treating diseases but also affect crop yield and food safety. We combine IoT technology with deep learning to build an IoT system for crop fine-grained disease identification. This system can automatically detect crop diseases and send diagnostic results to farmers. We propose a multidimensional feature compensation residual neural network (MDFC-ResNet) model for fine-grained disease identification in the system. MDFC-ResNet identifies from three dimensions, namely, species, coarse-grained disease, and fine-grained disease and sets up a compensation layer that uses a compensation algorithm to fuse multidimensional recognition results. Experiments show that the MDFC-ResNet neural network has better recognition effect and is more instructive in actual agricultural production activities than other popular deep learning models.

Методика прогноза напряженно-деформированного состояния крепи вертикального ствола на участке сопряжения с горизонтальной выработкой в соляных породах

The article proposes a method for predicting the stress-strain state of the vertical shaft lining in saliferous rocks at the drift landing section. The paper considers the development of geomechanical processes in the saliferous rock in the landing area, the support is viewed as a two-layer medium: the inner layer is concrete, the outer layer is compensation material. With this in view, the paper solves the problem of continuum mechanics in a spatial setting, taking into account the long-term deformation of salts and the compressibility of the compensation layer. Long-term deformation of saliferous rocks is described using the viscoplastic model of salt deformation into the numerical model, and the crushable foam model to simulate the deformation of the compensation layer. This approach considers all stages of the deformation of the compensation layer material and the development of long-term deformations of saliferous rocks, which makes it possible to increase the reliability of the forecast of the stress-strain state of the vertical shaft lining.

Stress compensation by deposition of a nonuniform corrective coating.

Surface deformation by coating stress is compensated by prefiguring the substrate with a radially nonuniform layer of dense silica. Stresses in the compensation layer and reflector are modeled using finite element analysis to determine the optimal thickness profile, with the deposited coating reducing the surface deformation by 90%. This process is intended to allow implementation of both the compensation layer and the traditional multilayer coating in a single vacuum cycle.

Post-release deformation and curvature correction of an electrothermally actuated MEMS bilayer platform

Surface micromachined devices are known to have residual stress-induced deformation. This paper presents the effects of residual stress on the flatness of an electrothermally actuated large aperture MEMS bilayer platform. The platform consists of a SiO2–Al composite plate of area 500 × 500 μm2 suspended over a cavity through bimorph actuators. The bilayer platform consists of 0.95 μm thick aluminum film on a thermally grown 0.75 μm thick silicon dioxide on a silicon substrate. Bimorph actuators also consist of laminated layers of silicon dioxide and aluminum of thicknesses the same as on the platform. The ensuing compressive stress in silicon dioxide (240 MPa) & tensile stress in aluminum (35 MPa) manifests itself in significant post-release curling of the bilayer platform. Finite Element Simulation is done in Coventorware® to analyze the room temperature post-release deformation behavior of the platform.In order to correct the platform curvature, two methods of stress counterbalancing i.e. (i) metal reinforcement framing, and (ii) deposition of a stress compensation layer are proposed and their effectiveness is investigated using FEM simulations. The simulation results show that a 1 μm thick gold reinforcement frame results in a 13 μm peak-to-valley height difference between center and corner of the platform, which improves to 6 μm for a gold reinforcement thickness of 3 μm. The maximum height difference reduces to 1 μm for silicon dioxide of thickness 0.75 μm. According to FEM results, the presence of a stress compensation layer at the top is more effective in curvature correction compared to metal reinforcement framing; however, the post-release elevation of the stress-compensated platform is 5 μm below the post-release elevation of the reinforced platform and 25 μm below the zero reference plane. To verify the simulation results, the platform is fabricated with a deposition of 1 μm thick silicon dioxide layer at the top. The fabricated platform exhibit significant improvement in post-release deformation with a stress compensation layer compared to an unbalanced platform.

A Lateral Double-Diffusion Metal Oxide Semiconductor Device with a Gradient Charge Compensation Layer

In order to better shield the substrate-assisted depletion (SAD) effect and improve the breakdown voltage of super-junction (SJ) devices, an SJ lateral double-diffusion metal oxide semiconductor device with a gradient charge compensation layer (gradient device) is proposed. The main feature of this structure is to introduce a gradient charge compensation layer between the SJ layer of a conventional device and the substrate. The depth of the gradient charge compensation layer increases gradually from the source to the drain. The charge distribution in the drift region is optimized by reducing the compensation charge on the side near the source and increasing the compensation charge on the side near the drain. Introduction of the layer improves shielding of the SAD effect, and the electric field on the surface of the structure is an approximately rectangular distribution, thus the breakdown voltage is improved. The simulation results show that the gradient device has 409-V breakdown voltage and a 9.5-MW cm−2 figure of merit with a drift region length of 21 μm. Compared with the conventional SJ structure (conventional device) with the same drift length, the breakdown voltage and figure of merit of the gradient device are increased by 57.3% and 137.5%, respectively.