Random-valued impulse noise removal using adaptive dual threshold median filter

Noise detection and its removal is very important in the image processing. Detection of noise is very crucial and significant in random valued impulse noise because it does not hamper the image pixels uniformly. This paper presents a novel and unique concept of adaptive dual threshold for the detection of random valued impulse noise along with simple median filter at noise removal stage. Simulation results shows that an efficient noise detection leads to a superior quality of de-noised image as compared to existing adaptive threshold based image de-noising techniques. Proposed threshold computation is based on averaging of pixel values of window which enhances the PSNR of our system as compared to existing median filter based image de-noising methods.     

Kernel-based fourth-order diffusion for image noise removal

The fourth-order partial differential equations have good performance on noise smoothing and edge preservation without creating blocky effects on smooth regions. However, for low signal-to-noise ratio images, the discrimination between edges and noise is a challenging problem. A novel kernel-based fourth-order diffusion is proposed in this paper. It introduces a kernelized gradient operator in the fourth-order diffusion process, which leads to more effective noise removal capability. Experiment results show that this method outperforms several previous anisotropic diffusion methods for noise removal and edge preservation.     

基于源质的煤基中间相小球体生成与可控演化

煤全组分族分离所得的密中质组是中间相小球体生成的来源物质（即源质）。以该源质为原料，制备煤基碳质中间相。考察了炭化过程中温度、恒温时间、氮气流速、原料进样方式和添加剂等因素对中间相小球体生成过程的影响，探讨了中间相小球体演化过程的可控性。结果表明：温度、恒温时间、进样方式是影响中间相小球体生成的主要因素，能够控制生成中间相小球体粒径大小；温度升高或恒温时间延长均会加剧原料分子的热反应，促进中间相小球体的生成和融并；大面积的融并将使粒度迅速增加，部分球体解体，球体数目下降，最终形成体中间相；进样方式主要通过影响小球体演化过程中挥发性气体的逸出及原料颗粒间热传递效率影响小球体的生成和发展；氮气流速起到辅助调控作用；添加剂的加入促进了原料成核，加速了小球体的生成。     

搪瓷承压水箱在空气源热泵中实际运用研究

随着经济的快速发展，人们的生活水平得到了显著的提升，由此，人们对生活的质量就有了更高的要求，尤其是对热水的要求，更是出现了显著的提升。当前，国内的空气源热水器行业发展的十分迅速，能够充分地满足人们对热水的需求，这使得空气源热泵在人们的生活中应用的越来越广泛。在本文中，介绍了空气源热泵的工作原理以及优点，并介绍了搪瓷承压水箱在空气源热泵中的实际应用。     

Unrelated toxin–antitoxin systems cooperate to induce persistence

Persisters are drug-tolerant bacteria that account for the majority of bacterial infections. They are not mutants, rather, they are slow-growing cells in an otherwise normally growing population. It is known that the frequency of persisters in a population is correlated with the number of toxin–antitoxin systems in the organism. Our previous work provided a mechanistic link between the two by showing how multiple toxin–antitoxin systems, which are present in nearly all bacteria, can cooperate to induce bistable toxin concentrations that result in a heterogeneous population of slow- and fast-growing cells. As such, the slow-growing persisters are a bet-hedging subpopulation maintained under normal conditions. For technical reasons, the model assumed that the kinetic parameters of the various toxin–antitoxin systems in the cell are identical, but experimental data indicate that they differ, sometimes dramatically. Thus, a critical question remains: whether toxin–antitoxin systems from the diverse families, often found together in a cell, with significantly different kinetics, can cooperate in a similar manner. Here, we characterize the interaction of toxin–antitoxin systems from many families that are unrelated and kinetically diverse, and identify the essential determinant for their cooperation. The generic architecture of toxin–antitoxin systems provides the potential for bistability, and our results show that even when they do not exhibit bistability alone, unrelated systems can be coupled by the growth rate to create a strongly bistable, hysteretic switch between normal (fast-growing) and persistent (slow-growing) states. Different combinations of kinetic parameters can produce similar toxic switching thresholds, and the proximity of the thresholds is the primary determinant of bistability. Stochastic fluctuations can spontaneously switch all of the toxin–antitoxin systems in a cell at once. The spontaneous switch creates a heterogeneous population of growing and non-growing cells, typical of persisters, that exist under normal conditions, rather than only as an induced response. The frequency of persisters in the population can be tuned for a particular environmental niche by mixing and matching unrelated systems via mutation, horizontal gene transfer and selection.     

A robust adaptive weighted constant modulus algorithm for blind equalization of wireless communications systems under impulsive noise environment

A robust adaptive weighted constant modulus algorithm is proposed for blind equalization of wireless communication systems under impulsive noise environment. The influence of the impulsive noise is analyzed based on numerical analysis method. Then an adaptive weighted constant modulus algorithm is constructed to adaptively suppress impulsive noise. Theoretical analysis is provided to illustrate that the proposed algorithm has a robust equalization performance since the impulsive noise is adaptively suppressed. Moreover, the proposed algorithm has stable and quick convergence due to avoidance of large misadjuntment and adoption of large step size. Simulation results are presented to show the robust equalization performance and the fast convergence speed of the proposed algorithm under both impulsive noise and Gaussian noise environments.     

船舶水润滑尾轴承结构设计研究进展

水润滑轴承的结构优化可以有效提高轴承的承载能力、冷却散热、减振降噪和摩擦学性能。在概述船舶水润滑尾轴承的优势和存在问题的基础上,分析归纳水润滑尾轴承内衬结构、内衬的厚度和硬度、轴承间隙、长径比、内衬表面粗糙度等结构设计参数的研究进展;以轴位水润滑尾轴承、内衬多层复合水润滑尾轴承和闭式水润滑尾轴承为例,介绍近年来几种新型水润滑尾轴承的结构设计,指出闭式水润滑尾轴承在内河及沿海船舶上具有广阔的应用前景,是未来的研究重点和发展趋势;建议水润滑尾轴承的研究应从以下方面着手,一是从微纳米尺度研究轴承微观界面润滑机制,二是在考虑轴承参数间耦合作用的基础上对轴承进行多目标优化,三是进一步研究闭式水润滑尾轴承及密封装置材料、结构和辅助装置以及水润滑添加剂,四是研究船舶水润滑尾轴承的设计规范,建立一定范围内精度满足工程需要的轴承设计计算经验公式,以简化轴承设计程序。     

Deposition of boron-containing coatings by electron-beam evaporation of boron-containing targets

Boron-containing films are promising materials for improving the hardness, wear-resistance and durability of mechanical parts used in industry. We describe a novel approach for deposition of such coatings – by using electron-beam evaporation of boron-containing target material (pure boron or boron nitride) in inert (helium) or chemically-active (oxygen, nitrogen, residual atmosphere) gases at medium vacuum. Boron-containing films deposited on titanium substrates were characterized using a nanohardness tester and a non-contact 3D profilometer. Elemental composition of the coatings was studied using raster electron microscope equipped with a device for EDX analysis. All boron-containing coatings provided significant improvement (by a factor of 4–16) in the microhardness of the substrate surface.     

减震隔声降噪地垫的研发

介绍我国分户楼板隔声及其隔声研究现状,详细阐述多层复合结构的减震隔声降噪地垫的结构、性能和安装,减震隔声降噪地垫与木地板配合使用,将其铺装于扫平层的140 mm厚现浇钢筋混凝土楼板之上,经江苏省建工建材检测中心检测,撞击声隔声为61 dB,能很好地满足住宅分户楼板撞击声隔声L'nT,W≤65 dB的要求。     

Application of differential evolution for cascaded multilevel VSI with harmonics elimination PWM switching

Harmonic elimination pulse width modulation (HEPWM) method has been widely applied to multilevel voltage source inverter (MVSI) to remove low frequency harmonics from its output voltage. However, the computation of the HEPWM switching angles for MVSI is very challenging due to several constraints, namely angle sequencing, very tight angular spacing and the numerous possibilities of angles distribution ratio. Realizing the potential of Differential Evolution (DE) to handle complex problems, this work proposes its application to solve the HEPWM problem for cascaded MVSI. Its emphasis is on improving the availability of HEPWM for higher output voltage by extending the maximum range of modulation index (M). It also removes the discontinuities in the switching angles and reduces the number of distribution ratio required to obtain the required solution. Compared to the most advanced (similar) work, i.e., 7-level MVSI with seventeen switching angles, DE covers a wider range of M; the maximum achievable M is 2.80. Furthermore, it exhibits very low second order distortion factor (DF₂): for the worst case, the value of DF₂ is 0.0014%. To verify the viability of the proposed algorithm, simulation is carried out and hardware prototype is constructed. Both results show very good agreement with the theoretical prediction.