自适应收缩函数的Contourlet变换图像去噪方法

针对传统图像在去噪过程中存在丢失细节且去噪效果不理想的情况,提出一种自适应收缩函数的Contourlet变换图像去噪方法.该方法利用Contourlet变换的基本形式,结合软阈值和硬阈值收缩函数的优点定义自适应收缩函数,并将其应用于图像去噪.实验结果表明,所提出的方法能有效消除噪点,图像的峰值信噪比及增强因子等图像质量指标有明显地提高,去噪后图像的视觉效果良好.     

超滤技术在城镇自来水厂改造中的应用

超滤技术能够彻底地消除存在于饮用水中的颗粒、病毒以及引起疾病的原生动物等,还可以减少水中的消毒副产物,所以它是自来水厂进行技术升级改造的最佳选择。PVC合金超滤膜有很高的精准度,同时它的渗透量也很大,又具有很强的抗污染能力。     

如何使旧墙翻新耐久恒远

随着经济和社会的发展,旧城改造是一个城市发展的必然阶段,也是提升城市品位和竞争力的有力举措。在旧城改造的进程中,将原有建筑的外墙改造翻新也成为了"旧城换新颜"不可缺少的系统工程。本文就如何使旧墙翻新、耐久恒远展开了分析和研究。     

基于图论的三构态助老变胞机构的设计与运动学分析

为了研发一款助老机器人,基于图论理论、机构的数综合,设计了一种可在2自由度、1自由度、0自由度之间切换的三构态助老变胞机构。针对变胞机构的2自由度行走构态,运用闭环矢量法进行了运动学分析,得到该变胞机构在该构态下关键位置的位移、速度、加速度等变化规律。分析结果显示,位移曲线在支撑期过渡到摆动期时位移变化较大,在步态周期的后40%内,速度、加速度均有较大变化,符合人体步态规律,表明该助老变胞机构设计是合理的。     

基于单间隔的暂态选线方法

单相接地故障其暂态特征不受消弧线圈、弧光接地、间歇性接地等影响,但是现有暂态法选线都是基于集中式装置实现的,不利于实现配网保护的就地化实现。本文提出一种仅依赖本间隔零序电流、电压的故障暂态分量进行选线的方法,即暂态小波功率方向选线法,并通过仿真对该方法进行了验证。     

Findings from a fleet test on the performance of two engine oil formulations in automotive CNG engines

This work presents a comparative assessment of engine oil performance on field test using urban transport vehicles powered by compressed natural gas engines using two different mineral oil formulations approved by engine manufacturer. The first one is considered as a baseline reference, and the second one is a higher quality formulation in terms of base stock refining and additive content. Higher quality oil has shown a significant enhanced lubricant performance, leading to reach the oil drain interval defined by engine manufacturer on these engines without penalties in maintenance costs. In order to assess oil performance, an oil analysis programme has been established for oil samples collected from vehicles operated under real service conditions in an urban transport fleet. Monitored parameters include oxidation, nitration, aminic anti‐oxidant additives depletion, anti‐wear additives depletion, total acid number, total basic number and remaining useful life number (as an estimation of anti‐oxidant additive depletion including aminic and zinc dialkyldithiophosphate). Results obtained in more than 90 samples from 15 different vehicles have shown higher degradation rates for low quality lubricant oil formulation. This deviation can be explained taking into account factors related with lower anti‐oxidant additives content and lower thermal stability that can be mainly related with the base stock quality. This lower oil performance can be finally converted into higher vehicle maintenance cost and lower engine reliability. Copyright © 2013 John Wiley & Sons, Ltd.     

Exponential wavelet iterative shrinkage thresholding algorithm with random shift for compressed sensing magnetic resonance imaging

We propose the use of exponent of wavelet transform (EWT) coefficients as a sparse representation which is combined with the iterative shrinkage/threshold algorithm (ISTA) for the reconstruction of compressed sensing magnetic resonance imaging. In addition, random shifting (RS) is employed to guarantee the translation invariance property of discrete wavelet transform. The proposed method is termed the exponential wavelet iterative shrinkage/threshold algorithm with random shifting (EWISTARS), which takes advantages of the sparse representation of EWT, the simplicity of ISTA, and the translation invariance of RS. Simulation results on brain, vertebrae, and knee MR images demonstrate that EWISTARS is superior to existing algorithms with regard to reconstruction quality and computation time. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Traveling wave fault locator for mixed,overhead, and underground teed transmission feeders

Society is increasingly concerned about the environmental impact of energy systems, and prefers to locate power lines underground. This is especially true in regions of outstanding natural beauty or if they affect environmental/political/planning constrained areas. However, the use of underground sections within a predominantly overhead feeder introduces significant problems for the auto‐reclosure of circuit breakers. Auto‐reclosure is important on an overhead feeder, since most faults are transient and, once the feeder has been de‐energized, the insulation strength of the air at the fault recovers and the line can be restored to service. Faults on an underground cable are different because, once the insulation is damaged, the fault is normally permanent. In addition, if the breaker is allowed to reclose onto a cable fault, the area of damage increases and health and safety concerns exist for humans in the vicinity of the faulted cable section. The main purpose of the traveling‐wave‐based measurement scheme described in this paper is to locate a fault on a teed transmission feeder with mixed overhead and underground sections. Simulation results demonstrate that the fault locator can accurately locate all realistic faults, including ones that are high resistance or occur at nonideal points on wave. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

SBS改性沥青中SBS含量测试方法研究

对基质沥青、SBS和6种SBS含量的SBS改性沥青进行了红外光谱测试.结果表明,SBS改性沥青红外光谱中966,699 cm-1处SBS基团特征吸收峰和810 cm-1处沥青基团特征吸收峰,可作为SBS定性和定量分析依据;单因素方差分析和多重均值比较表明,SBS含量对699 cm-1与810 cm-1处特征峰吸收面积比(A699/A810)具有显著性影响,且不同SBS含量的A699/A810值之间存在显著差异;A699/A810与SBS含量呈现良好线性关系(相关系数0.9983),可将A699/A810作为SBS含量定量分析指标.应用傅里叶变换红外光谱(FTIR)技术可实现SBS改性沥青中SBS含量的准确、快速测试.     

乙烯基酯树脂对玻璃纤维的浸润研究

为研究通用乙烯基酯树脂基体对玻璃纤维的浸润性能,考察了两种乙烯基酯树脂基体、三种玻璃纤维。通过添加助剂改变树脂体系的表面张力,以靶环实验测试不同树脂体系对三种玻璃纤维的浸润速率,采用RTM工艺灌注平板试验验证各树脂体系对玻璃纤维的浸润效果,优选出匹配性最好的树脂基体和玻璃纤维。研究表明,降低树脂体系表面张力有利于树脂对玻璃纤维的充分浸润,批产应用效果十分明显。