Accurately estimating reflectance parameters for color and gloss reproduction

A new method is described to estimate diffuse and specular reflectance parameters using spectral images, which overcomes the dynamic range limitation of imaging devices. After eliminating the influences of illumination and camera on spectral images, reflection values are initially assumed as diffuse-only reflection components, and subjected to the least squares method to estimate diffuse reflectance parameters at each wavelength on each single surface particle. Based on the dichromatic reflection model, specular reflection components are obtained, and then subjected to the least squares method to estimate specular reflectance parameters for gloss intensity and surface roughness. Experiments were carried out using both simulation data and measured spectral images. Our results demonstrate that this method is capable of estimating diffuse and specular reflectance parameters precisely for color and gloss reproduction, without requiring preprocesses such as image segmentation and synthesis of high dynamic range images.     

Jointly beam stealing attackers detection and localization without training: an image processing viewpoint

Recently revealed beam stealing attacks could greatly threaten the security and privacy of IEEE 802.11ad communications. The premise to restore normal network service is detecting and locating beam stealing attackers without their cooperation. Current consistency-based methods are only valid for one single attacker and are parameter-sensitive. From the viewpoint of image processing, this paper proposes an algorithm to jointly detect and locate multiple beam stealing attackers based on RSSI (Received Signal Strength Indicator) map without the training process involved in deep learning-based solutions. Firstly, an RSSI map is constructed based on interpolating the raw RSSI data for enabling high-resolution localization while reducing monitoring cost. Secondly, three image processing steps, including edge detection and segmentation, are conducted on the constructed RSSI map to detect and locate multiple attackers without any prior knowledge about the attackers. To evaluate our proposal’s performance, a series of experiments are conducted based on the collected data. Experimental results have shown that in typical parameter settings, our algorithm’s positioning error does not exceed 0.41 m with a detection rate no less than 91%.     

基于虚坡模型的交叉口交通流的解耦方法

交叉口交通流的模型是进行红绿灯优化管理仿真模拟的基础。传统的方法仍有其不足之处，主要表现在对统计手段有较大的依赖性。为此，提出了一种基于虚坡模型的解耦方法，它将路口的红灯黄灯效应用假想路障代替，将一个方向上的车流对另一个方向上车流的影响用另一个假想的宽度变化的路障代替，而假想路障则在虚坡模型中表示为速度为零的车辆。由此，交叉口两个方向上的交通流被表示为两条独立道路上的交通流，用虚坡模型算出每一方向上各车的行驶规律，并求出折合行驶延误时间。调整信号灯切换时问令总体延误时问为最小，就能得到最佳的信号灯管理方案。通过对一个大规模问题的试算，得到了有用的结果，表明可用虚坡模型通过仿真手段对交通管理问题进行直接研究。     

小波矩量法分析环形微带缝隙天线*

将矩量法和小波变换理论结合起来,应用于求解电磁场积分方程,分析计算了环形微带缝隙天线磁流分布、驻波、阻抗特性和辐射方向图,通过用小波基代替一般的分域基矩量法中的权函数和基函数,使矩量法中与算子相对应的阻抗矩阵变成为大量元素为零的稀疏矩阵,减小了数值方法对存储量的要求,在达到允许精度的前提下,使计算量显著降低。文中给出计算实例,验证该方法,计算结果与用一般矩量法计算结果和实际测试结果相比,吻合较好。     

高温抗烧结吸附剂对SeO2捕集性能

使用气固瞬时反应装置在700~1100℃下对不同氧化物（氧化镁、氧化铁、氧化铝、氧化钙）的硒捕集性能进行研究,确定吸附产物性质。基于此选取相应的典型矿物及双组分抗烧结吸附剂改善硒高温吸附能力。结果表明：900℃前氧化钙捕集效果最好,但1100℃时其吸附量迅速降低到167.59μg/g;γ-氧化铝在高温下捕集效果较好,1100℃时吸附量可达415.04μg/g,这与其优异的孔隙结构有关。钙基矿物方解石因其具有一定的抗烧结能力和发达的孔隙结构,表现出更好的高温捕集能力,1100℃时吸附量可提高到1064.97μg/g。双组分吸附剂高温捕集能力展现出不同程度的提高。钙-铝基吸附剂高温捕集性能提高相对较小;而钙-硅基吸附剂在高温下效果远高于单组分吸附剂,与氧化钙相比,1100℃时可提高1787.21μg/g。     

Effects of Al addition on the phase transformation and interfacial evolution in multilayer Ti-B4C composite

The fully-dense multilayer Ti-B₄C composite doped with 6 wt% Al was fabricated via tape-casting and hot-pressing sintering at 1800 °C and under a uniaxial pressure of 30 MPa for 60 min. The effects of Al addition on the phase composition, interfacial microstructure and fracture toughness of the laminate composite were investigated. Based on the results of WDS and EDS, Al addition was proved to be effective on accelerating atom diffusion between Ti and B₄C due to the melting pool around interface where liquid Al enriched, besides, it helps to transform the interfacial bonding method of physical to metallurgical. Finally, the improvement on toughness of Al doped composite can be attributed to the strong metallurgical bonding and hybrid fracture mode of interface. Our study may provide a potential method for producing high strength and toughness multilayer metal/ceramic composites.     

A novel fabrication route to microlaminated TiB2–NiAl composite sheet with {111}<μνω> texture by roll bonding and annealing treatment

Microlaminated TiB₂–NiAl composite sheet consisting of alternating NiAl and TiB₂-rich layers has been successfully fabricated. This fabrication method is composed of roll bonding for producing a multi-laminated Ni–(TiB₂/Al) sheet from Ni sheets and TiB₂/Al composite sheets, and of subsequent annealing treatment for forming a NiAl intermetallic phase by reaction diffusion. Microlaminated TiB₂–NiAl composite sheet obtained by this method exhibits strong {111}<μνω> texture. The formation mechanism of such texture by reaction diffusion has been discussed in view of texture inheritance. This method could utilize reaction diffusion to control texture component of materials, which is expected to provide an access to synthesize materials with texture for special requirement.     

Experimental evidence of structural evolution for TiB2 microcrystal under externally high stresses

The morphology evolution and defect structure of TiB₂ microcrystals treated under high stresses were analyzed using scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). The results show that hexagonal TiB₂ with large particle size gradually evolved to flowerlike TiB₂ with small particle size under high stresses. The evolution process is mainly determined by the preferential cleavage of TiB₂ microcrystal, and the presence of multiple lamellar nanotwin and edge dislocation directly provides some evidence of plastic deformation and structural evolution. For clarity, a possible model is suggested based on the HTREM observation and the natural properties of TiB₂ materials to explain the process mechanism.     

Processing of high-performance Co doped Y2O3 as a single-phase electrolyte for low temperature solid oxide fuel cell (LT-SOFC)

The high-performance single-phase semiconductor materials with higher ionic conductivity have drawn substantial attention in fuel cell applications. Semiconductor materials play a key role to enhance ionic conductivity subsequently promoting low temperature solid oxide fuel cell (LT-SOFC) research. Herein, we proposed a semiconductor Co doped Y₂O₃ (YCO) samples with different molar ratios, which may easily access the high ionic conductivity and electrochemical performances at low operating temperatures. The resulting fabricated fuel cell 10% Co doped Y₂O₃ (YCO-10) device exhibits high ionic conductivity of ∼0.16 S cm⁻¹ and a feasible peak power density of 856 mW cm⁻² along with 1.09 OCV at 530 °C under H₂/air conditions. The electrochemical impedance spectroscopy (EIS) reveals that YCO-10 electrolyte based SOFC device delivers the least ohmic resistance of 0.11–0.16 Ω cm² at 530-450 °C. Electrode polarization resistance of the constructed fuel cell device noticed from 0.59 Ω cm² to 0.28 Ω cm² in H₂/air environment at different elevated temperatures (450 °C to 530 °C). This work suggests that YCO-10 can be a promising alternative electrolyte, owing to its high fuel cell performance and enhanced ionic conductivity for LT-SOFC.