基于AOTF的在线红外光谱测量系统

介绍了一种新型的红外光谱测量系统，它由准直发射系统和聚焦接收系统两大部分组成，以声光可调谐滤光器（AOTF）为色散元件，连续改变AOTF的驱动频率就能实现快速波长扫描，达到实时测量目的。该系统具有结构简单、测量快速等特点，可用于在线有害气体检测和红外光谱分析。实验表明，系统光谱测量范围2．5－5μm，光谱分辨力为10nm。     

Acousto-optic tunable filter sidelobe analysis and reduction with telecentric confocal optics

The acousto-optic tunable filter (AOTF) has optical sidelobes that are due to the acoustic field produced by the transducer. These sidelobes were analyzed by wave-vector phase matching between the optical and acoustic fields, which correlated with measurements made with a TeO2 AOTF. A white-light point source was filtered and imaged, showing reasonably large and slowly decreasing sidelobes covering a large spectral range. This effect reduces the image quality of an AOTF system by producing faint secondary images of bright objects. The image quality can be improved with a telecentric confocal optical arrangement in which the angular shift of the sidelobes is greatly reduced, producing a much sharper image. This effect was also demonstrated experimentally with the point source.     

红外AOTF调谐关系及其衍射光波长特性研究

对红外AOTF的分光原理和两级衍射光波长特性进行了理论与实验分析.结果表明:AOTF的驱动频率与衍射光波数基本成线性关系;入射角小于57.6°时,两级衍射光波长不等,波长差随驱动频率的增加而减小.分析了影响AOTF分辨率的主要因素,提出了改进方法.     

Focal shift and extended focal depth with tunable pupil filter

Extended focal depth and focal shift are very important in microscopy, imaging and optical storage systems, and have attracted much attention in recent years. In order to obtain the extended focal depth and focal shift, a new kind of tunable pupil filter is proposed in this article. It consists of one half-wave plate between two quarter-wave plates, and the half-wave plate is made up of two zones that can rotate with respect to each other. By analyzing the intensity distribution in the focal region of the optical system with such a device, it reveals that focal shift can be realized by rotating any zone of the half-wave plate. When the phase difference of the two zones is π, the extended focal depth and transverse superresolution can be obtained at the same time. Therefore, it may be feasible to use such a tunable pupil filter in optical systems that need focal shift and extended focal depth.     

一种以AOTF为核心的农药荧光检测系统

提出了一种将 AOTF 技术用于农药含量检测的荧光光谱系统。该系统分别采用以α-Quartz,TeO2 晶体作为声光介质的激发和发射色散元件 AOTF,以高压短弧氙灯为激发光源,利用光纤探测并传输荧光,由数据采集卡进行数据接收和 A/D 转换。该系统通过声光调制产生单色光,由超声射频的变化实现光谱扫描,没有机械调谐部件,故波长切换快、结构简单。西维因农药的荧光特性测量结果表明,系统的荧光波长范围为 500-750nm, 光谱分辨率为 10nm。当激发光波长为320nm,荧光波长为 647nm,西维因溶液浓度为 0.0-120.0μg/L 时,系统具有较好的线性关系,线性相关系数 r 为 0.9991。它可用于对粮食作物中的农药残留的检测和荧光光谱分析。     

彩色合成中AOM设计分析

利用铌酸锂晶体为压电换能器,熔石英为声光互作用介质,研制出调制速度为32MHz、工作频率为180MHz、渡越时间为15ns、用于RGB彩色合成中的的声光调制器,文中主要讨论和分析了Q参数与调制器中心工作频率、换能器长度的关系;讨论了R参数对衍射光束形状的影响及与衍射效率的关系,还讨论并确定了换能器最佳尺寸,经测试,高速率声光调制器衍射效率为47％,并测试了调制速度。     

ECG steganography based on tunable Q‐factor wavelet transform and singular value decomposition

The article presents a novel ECG steganography scheme based on the tunable Q‐factor wavelet transformation (TQWT) and also singular value decomposition (SVD) techniques that ensure better safety and confidentiality of patient information. Initial parameters such as Q, r, and J are used to decompose the cover signal into individual frequency sub‐bands with the tunable Q‐factor wavelet transform (TQWT). The singular value decomposition (SVD) technique is used to further decompose high‐frequency sub‐band coefficients into singular values. The watermark information is then embedded with high‐frequency sub‐band coefficients by involving the quantization process. The performance of this proposed system is successfully evaluated by considering various metrics, such as peak signal to noise ratio (PSNR), structural similarity index (SSIM), percentage residual difference (PRD), and bit error rate (BER). The simulation results of the proposed scheme are observed to be better than other traditional algorithms.     

Intelligent controlled shunt active power filter for voltage and current harmonic compensation in microgrid system

An integrated microgrid with a novel shunt active power filter (APF) using Elman neural network (ENN) is proposed in this study. The microgrid consists of a storage system, a photovoltaic (PV) system, the shunt APF, a linear load, and a nonlinear load. Moreover, the master/slave control algorithm is adopted in the microgrid. The storage system, which is considered as the master unit, is adopted to control the active and reactive power outputs (P/Q control) in grid-connected mode and the voltage and frequency of the microgrid (V/f control) in islanded mode. Furthermore, the PV system is considered as the slave unit to implement P/Q control in both grid-connected and islanded modes. In addition, the proposed shunt APF possesses dual functions of voltage and current harmonic compensation for microgrid under voltage harmonic propagation and nonlinear load to reduce the voltage and current total harmonic distortions (THD) effectively. Additionally, an ENN controller is adopted in the proposed shunt APF to improve the transient and steady-state responses of DC-link voltage during the switching between the grid-connected mode and islanded mode. Finally, some simulation results are provided to verify the feasibility and the effectiveness of the integrated microgrid with the intelligent controlled shunt APF.     

The design of composite adaptive morphological filter and applications to Rician noise reduction in MR images

Composite filters based on morphological operators are getting considerably attractive to medical image denoising. Most of such composite filters depend on classical morphological operators. In this article, an optimal composite adaptive morphological filter (F_CAMF) is developed through a genetic programming (GP) training algorithm by using new nonlocal amoeba morphological operators. On one hand, we propose a novel method for formulating and implementing nonlocal amoeba structuring elements (SEs) for input‐adaptive morphological operators. The nonlocal amoeba SEs in the proposed strategy is divided into two parts: one is the patch distance based amoeba center, and another is the geodesic distance based amoeba boundary, by which the nonlocal patch distance and local geodesic distance are both taken into consideration. On the other hand, GP as a supervised learning algorithm is employed for building the F_CAMF. In GP module, F_CAMF is evolved through evaluating the fitness of several individuals over certain number of generations. The proposed method does not need any prior information about the Rician noise variance. Experimental results on both standard simulated and real MRI data sets show that the proposed filter produces excellent results and outperforms existing state‐of‐the‐art filters, especially for highly noisy image. © 2015 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 25, 15–23, 2015     

柴油机过滤体逆向喷气再生系统的模拟与试验研究

进行了柴油机过滤体逆向喷气再生系统的模拟与试验研究。采用计算流体力学软件Star-Cd,利用当量连续方法,建立了微粒捕集器的数学模型,分析了反吹管结构对过滤体内反吹气流的流动均匀性和压力损失的影响,并进行了试验验证。计算结果与试验结果有较好的一致性,表明所建立的流动模型可用来预测不同捕集器结构的过滤体内部的流动特征;螺旋喷吹的双反吹管结构可使过滤体的再生更加均匀。     

具有形状记忆合金丝的复合材料轴转子系统的振动与稳定性

提出具有SMA丝的复合材料轴-盘-刚性支承转子系统的数学模型,研究转子系统的振动与稳定性。将轴视为一个平行于轴线方向埋入SMA丝的薄壁复合材料空心梁,盘为各向同性刚性圆盘,轴位于刚性轴承上。基于变分渐进法(VAM)描述复合材料薄壁梁的变形,基于Brinson热力学本构方程计算SMA丝的回复应力,采用Hamilton原理推导出系统的运动方程,采用Galerkin法进行模型离散化和近似数值计算。着重分析SMA丝含量和初始应变对复合材料轴振动固有频率和转子系统临界转速的影响。研究结果表明,所建立的动力学模型能够用于揭示SMA对转子系统的振动与稳定性的影响机理。     

Multivariate analysis of a biologically activated carbon (BAC) system and its efficiency for removing PAHs and aliphatic hydrocarbons from wastewater polluted with petroleum products

The efficiency of a biologically activated carbon system for treating wastewater polluted with petroleum products was examined and the effects of process parameters on its efficacy were evaluated. In each experiment 17 alkylated and 19 non-alkylated polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs, C₁₀–C₄₀) were extracted using semipermeable membrane devices from wastewater before and after treatment. The acquired data during experiments were analyzed using principal component analysis (PCA). The treatment system robustly removed dissolved PAHs across the studied ranges of the process parameters, providing overall removal efficiencies of 96.9–99.7% for the sum of 36 PAHs. However, the major contributor to their removal was sorption rather than biodegradation, and despite the general efficiency of the process there was up to a 9-fold range in the sums of quantified PAHs in the effluents between experiments. Combinations of long process contact time (24 h) with high temperature (24 °C) and moderate oxygen concentration (6–7 mg O₂ L⁻¹) resulted in good removal of bioavailable PAHs. The removal of TPHs was more dependent on biological activities during the wastewater treatment, and consequently more dependent on the process parameters. In addition, small but significant proportions of PAHs were volatilized and released during the wastewater treatment.     

Design and comparative performance analysis of different chirping profiles of tanh apodized fiber Bragg grating and comparison with the dispersion compensation fiber for long-haul transmission system

Various dispersion compensation units are presented and evaluated in this paper. These dispersion compensation units include dispersion compensation fiber (DCF), DCF merged with fiber Bragg grating (FBG) (joint technique), and linear, square root, and cube root chirped tanh apodized FBG. For the performance evaluation 10 Gb/s NRZ transmission system over 100-km-long single-mode fiber is used. The three chirped FBGs are optimized individually to yield pulse width reduction percentage (PWRP) of 86.66, 79.96, 62.42% for linear, square root, and cube root, respectively. The DCF and Joint technique both provide a remarkable PWRP of 94.45 and 96.96%, respectively. The performance of optimized linear chirped tanh apodized FBG and DCF is compared for long-haul transmission system on the basis of quality factor of received signal. For both the systems maximum transmission distance is calculated such that quality factor is ≥ 6 at the receiver and result shows that performance of FBG is comparable to that of DCF with advantages of very low cost, small size and reduced nonlinear effects.     

Integrating failure analysis and risk analysis with quality assurance in the design phase of medical product development

Today, manufacturing operates as a global network, which has created more awareness of the quality of products and services. A systematic and rational way of managing quality assurance is currently lacking. This can cause serious problems in sectors such as the medical industry, as product failure may not only cause time delays, but also create risks for the health and safety of patients and users. This paper proposes a quality assurance approach that incorporates risk analysis (based on ISO14971) and failure analysis (based on FMEA) into the product design phase to assure product quality in the short term and facilitate global manufacturing practices in the long run. The proposed approach includes a Markov model to predict product failure from a customer perspective, which serves as a checkpoint for feedback to provide a basis for quality assurance. A medical equipment firm is used as a test-bed to illustrate how the proposed approach works and to verify its effectiveness.     

Stress assessment based on Ergonomics coupled with image-processing tools and techniques for lean product design and development

This paper presents an innovative lean ergonomic tool (LET) for mental stress through facial muscle activity assessment. An image-processing tool has been developed based on the analysis of facial angles. These angles were perceived by analyzing the stress levels of product development team members at certain conditions. A total number of 26 subjects participated in the experiments. On the basis of angular deviation levels, a stress level classification scheme was developed using neutral position of each team members for each task. Through statistical analysis, team members were divided into the groups of same degree of stress level. Each group was assigned a numerical expression value which was relative to the perceived stress level of that group for each task. Using five distinct action categories, a criterion for the evaluation of stress level was proposed which was validated through two distinct case studies. The developed LET will help the top management in taking corrective actions to reduce the stress level during product design and development.     

Treatment and recycling system optimisation with activity-based costing in WEEE reverse logistics management: an environmental supply chain perspective

Waste electrical and electronic equipment (WEEE) reverse logistics management has increasingly received much attention in recent years not only because of the fast increase of WEEE but also the legislations in many developed countries. This paper focuses on the treatment and recycling system, and proposes a two-stage multi-objective decision framework. In the treatment stage, the responsible producer selects treatment suppliers under extended producer responsibility by a pre-emptive goal programming model. After the wastes are depolluted and transformed to recyclable materials, the process enters the recycling stage in which the decision-maker plans the reclaimed material production by a linear programming model for profit maximisation. An illustrative case study is presented, and the sensitivity analyses show that the ranking of suppliers is more stable than the quantities allocated to suppliers under different priority structures, so ranking of suppliers should also be given attention in such multi-objective decision-making. In addition, a decision model with environmental constraints can reduce the production of the products that have more environmental impacts.