Solution-processed,flexible and broadband photodetector based on CsPbBr_3/PbSe quantum dot heterostructures

Due to their promising applications in foldable displays,optical communication equipment and environmental monitoring systems,flexible and broadband optoelectronic devices have gained extensive attention in recent years.Here,a flexible and broadband photodetector based on CsPbBr₃/PbSe quantum dot(QD) heterostructures is firstly presented.The integrated QD heterostructures possess consecutive detection range from ultraviolet(UV) to long-wave length infrared(LW-IR) regions with efficient light absorption and chemical stability,in comparison with the pristine PbSe QDs.Systematic material characterizations reveal the improved exciton dissociation,carrier transport and carrier lifetime of the QD heterostructures.Flexible photodetector Ag/CsPbBr₃/PbSe/Ag demonstrate a high responsivity of 7.17 A/W with a specific detectivity of 8.97 × 10¹² Jones under 25 μW/cm² 365 nm illumination at 5 V.Furthermore,it could maintain 91.2 %(or 94.9 %) of its initial performance even after bending for thousands of times(or exposing in ambient air for 4 weeks).More importantly,its re s ponse time is shortened more than three orders of magnitude as that of pristine PbSe QDs-based photodetectors.Therefore,it provides a feasible and promising method for the next-generation high-performance broadband photodetectors via constructing heterostructures of various QDs.     

集成电极的复合混沌混合芯片的快速制备及表征

试剂的有效混合是化学和生化反应的前提条件,因此混合成为微全分析系统的重要功能单元.本文介绍了一种通道中集成氧化铟锡(ITO)电极的聚二甲基硅氧烷(PDMS)-玻璃复合混沌混合芯片的快速制备方法,对PDMS的混合通道表面进行了硅溶胶改性.首次用集成的电极和酸碱反应过程中的电导变化对其混合效果进行了评价.利用玻璃各向同性刻蚀特点,一次曝光和一次刻蚀得到了混沌混合微通道结构的母板.利用光辅助原位聚合的方法快速制备了与母板微结构互补的聚甲基丙烯酸甲酯(PMMA)阳模,利用PI)MS原位聚合的方法复制得到了与玻璃母板结构相同的混沌混合通道结构的芯片.用电导法对芯片的混合有效性进行了表征.PDMS复制芯片与ITO玻璃永久封合即得全透明的复合混沌混合芯片.本文介绍的加工方法无需二次曝光及SU-8光刻胶,容易多次复制,在微流控分析芯片中将有广泛应用.     

On-line tuning system of multivariate dEWMA control based on a neural network approach

The double exponentially weighted moving average (EWMA) controller is a popular algorithm for on-line quality control of semiconductor manufacturing processes. The performance of the closed-loop system hinges on the adequacy of the two weight parameters of the double EWMA equations. In 2004, Su and Hsu presented an approach based on the neural technique for ‘on-line’ tuning the weight of the single EWMA equation in the single-input single-output (SISO) system. The present paper extends the neural network on-line tuning scheme to the double EWMA controller for the non-squared multiple-input multiple-output (MIMO) system, and validates the control performance by means of a simulated chemical–mechanical planarization (CMP) process in semiconductor manufacturing. Both linear and non-linear equipment models are considered to evaluate the proposed controller, coupling with the deterministic drift, the Gaussian noise and the first-order integrated moving average (IMA) disturbance. It has been shown from a variety of simulation studies that the proposed method exhibits quite competitive control performance as compared with the previous control system. The other merit of the proposed approach is that the tuning system, if sufficient training in a neural network is available, can be practicably applied to complex semiconductor processes without undue difficulty.     

基于深度置信网络与信息融合的齿轮故障诊断方法

针对齿轮在复杂运行工况下故障特征提取困难,传统故障诊断方法的识别精度易受人工提取特征的影响,以及单传感器获取信息不全面等问题,提出基于深度置信网络(DBN)与信息融合的齿轮故障诊断方法.通过多传感器信息融合技术对每个传感器采集的振动信号进行数据层融合;利用DBN进行自适应特征提取从而实现故障分类.为了避免因人为选择DB...     

A manufacturing network design model based on processor and worker capabilities

This paper presents an optimization methodology to design networks of manufacturing facilities producing several products under deterministic demand. The bill of materials and the operations for each product are taken into account through the use of a product-state graph. Starting from the current state of the manufacturing network, the approach considers a multi-period planning horizon. For each period it specifies the facilities to open within the set of current and potential facilities, the mission for each of the centres in the selected facilities, the equipment to be used for producing the goods, and the structure of the network. Taking human resource competencies into account, the approach selects the type of workers to use for executing the manufacturing tasks. The transfer of resources between plants is also considered. A multi-period mixed integer linear programming model is formulated, a solution method based on the addition of specialized cuts is proposed and computational results are presented.     

A mathematical formulation and anarchic society optimisation algorithms for integrated scheduling of processing and transportation operations in a flow-shop environment

This paper addresses a permutation flow-shop scheduling problem where there are a finite number of transporters to carry jobs from each machine to its subsequent machine. The problem is first formulated as a mixed-integer linear programme, and then two anarchic society optimisation (ASO) algorithms are developed to solve large-sized instances of the problem. The numerical experience shows that the ASO algorithms are considerably effective and efficient. Finally, a sensitivity analysis is carried out to study the performance of the manufacturing system versus the transportation times and the number of transporters.     

基于空时块编码和正交脉冲的MIMO系统性能研究

为了有效利用脉冲无线电(IR)的短距离、高数据速率以及多输入多输出(MIMO)通信系统的更大容量,提出了一种基于空时块编码(STBC)和正交脉冲的MIMO超宽带(UWB)通信系统。具体实现是通过对标准单输入单输出(SISO)脉冲无线电系统的直接序列超宽带作为多址(MA)技术的IR-MA信号模型以及信道模型、收发器结构和检测方法的分析,提出了一种把空时块编码和正交脉冲相结合的新方法,并采用FS-rake相干接收(CR)和非相干接收(NCR)技术及IEEE UWB信道模型对其获得的空间分集和编码性能进行了研究,从而得到可以相对较好地描述高信噪比时的性能变化趋势的理论上限值。仿真结果表明,这种STBC-IR方案相比于传统的单链路-脉冲无线电(SL-IR)方案,可获得更好的空间分集和编码增益,可用于增加传输距离和减少rake接收机的复杂性,而且在UWB通信中,STBC-IR方案还能很好地消除定时抖动的影响。     

基于自适应浸入与不变的VTOL飞行器跟踪控制

针对输入存在不确定干扰的垂直起降(VTOL)飞行器的跟踪控制问题,提出了一种基于自适应系统浸入与不变(II)的控制方案:对于不确定性输入干扰,采用自适应II方法对于扰进行实时估计补偿;为便于控制器设计,采用系统分解技术将原系统解耦成一个最小相位误差子系统和一个非最小相位子系统,将原系统的输出跟踪问题转换为两个误差子系统的镇定问题。基于自适应II估计律和滑模变结构控制方法分别设计了两个子系统的控制器,所设计的控制器能够保证两个闭环子系统指数稳定。仿真结果表明,上述控制方案在干扰估计精度和收敛速度方面明显优于传统自适应估计方法,能够实现飞行器对给定轨迹的准确跟踪,同时抑制输入干扰对系统性能的不良影响。     

Application of a generic bow-tie based risk analysis framework on risk management of sea ports and offshore terminals

Ports and offshore terminals are critical infrastructure resources and play key roles in the transportation of goods and people. With more than 80 percent of international trade by volume being carried out by sea, ports and offshore terminals are vital for seaborne trade and international commerce. Furthermore in today's uncertain and complex environment there is a need to analyse the participated risk factors in order to prioritise protective measures in these critically logistics infrastructures. As a result of this study is carried out to support the risk assessment phase of the proposed Risk Management (RM) framework used for the purpose of sea ports and offshore terminals operations and management (PTOM). This has been fulfilled by integration of a generic bow-tie based risk analysis framework into the risk assessment phase as a backbone of the phase. For this reason Fault Tree Analysis (FTA) and Event Tree Analysis (ETA) are used to analyse the risk factors associated within the PTOM. This process will eventually help the port professionals and port risk managers to investigate the identified risk factors more in detail. In order to deal with vagueness of the data Fuzzy Set Theory (FST) and possibility approach are used to overcome the disadvantages of the conventional probability based approaches.     

基于模糊粗糙集和鲸鱼优化支持向量机的化工过程故障诊断

针对化工过程复杂,故障数据量大、属性多,难以保证故障诊断准确率和速度的问题,提出了一种基于模糊粗糙集(fuzzy rough sets,FRS)和鲸鱼优化的支持向量机(support vector machine,SVM)的化工过程故障诊断方法.通过对化工过程历史数据分析,判别故障类型.首先,利用模糊粗糙集对离散化后的...     

基于主动阻尼的屈曲梁准零刚度隔振技术研究

准零刚度(QZS)隔振系统具有高静刚度-低动刚度的特性,能够对低频振动进行有效抑制,而主动阻尼能够显著降低系统的共振峰值同时保持系统高频传递特性不变.因此,将准零刚度隔振系统与主动阻尼相结合,可以有效提升系统的超低频隔振性能.以屈曲梁准零刚度隔振器为研究对象,基于系统动力学模型,引入主动阻尼控制策略,通过理论分析研究了...     

A study on construction of a kaizen case-base and its utilisation: a case of visual management in fabrication and assembly shop-floors

In this paper, focusing on visual management (VM) as one of the kaizen technologies, a procedure for its new case development is discussed. This procedure consists of two portions. The first portion is construction of kaizen case-base, namely: (1) correction and analysis of kaizen cases; (2) establishment of drivers and instances of investigated kaizen case; and (3) analysis of proximity relationship among kaizen cases. The second portion is utilisation of kaizen case-base, namely: (4) selection of kaizen case from kaizen case-base; (5) consideration of the other related kaizen cases; and (6) new kaizen case design. A case study is performed to assure the relevance of the proposed procedure by focusing on ‘dispatching board’, a typical VM technology. Through collaboration with a factory eager to implement VM, the proposed procedure is qualified by experts as a useful method for kaizen knowledge transfer.     

Fill factor enhancement of organic solar cells based on a wide bandgap phosphorescent material and C60

Planar heterojunction organic solar cells using wide bandgap phosphorescent material bis[2-(4-tertbutylphenyl)benzothiazolato-N,C^2'] iridium (acetylacetonate) [(t-bt)₂Ir(acac)] as electron donor and fullerene (C₆₀) as electron acceptor were fabricated. A large open circuit voltage of 0.94 V was achieved due to low highest occupied molecular orbital level of (t-bt)₂Ir(acac). The effect of different hole transport layers and substrate heating were investigated to improve fill factor. It is shown that the open circuit voltage is strongly influenced by the interface energy barrier, whereas the fill factor is mainly limited by the charge carrier transport properties in active materials. The fill factor was significantly improved by either using hole transport layer with high carrier mobility or increasing the hole mobility of (t-bt)₂Ir(acac). A power conversion efficiency of 2.10% under AM 1.5 solar illumination at an intensity of 100 mW/cm² was achieved by heating the substrate during the deposition of active materials.     

A cell‐based smoothed discrete shear gap method (CS‐FEM‐DSG3) based on the C0‐type higher‐order shear deformation theory for dynamic responses of Mindlin plates on viscoelastic foundations subjected to a moving sprung vehicle

A cell‐based smoothed discrete shear gap method (CS‐FEM‐DSG3) based on the first‐order shear deformation theory (FSDT) was recently proposed for static and dynamic analyses of Mindlin plates. In this paper, the CS‐FEM‐DSG3 is extended to the C⁰‐type higher‐order shear deformation plate theory (C⁰‐HSDT) and is incorporated with damping–spring systems for dynamic responses of Mindlin plates on viscoelastic foundations subjected to a moving sprung vehicle. At each time step of dynamic analysis, one four‐step procedure is performed including the following: (1) transformation of the weight of a four‐wheel vehicle into the sprung masses at wheels; (2) dynamic analysis of the sprung mass of wheels to determine the contact forces; (3) transformation of the contact forces into loads at nodes of plate elements; and (4) dynamic analysis of the plate elements on viscoelastic foundations. The accuracy and reliability of the proposed method are verified by comparing its numerical solutions with those of other available numerical results. Copyright © 2014 John Wiley & Sons, Ltd.     

A fast,memory efficient and robust sparse preconditioner based on a multifrontal approach with applications to finite‐element matrices

In this article, we introduce a fast, memory efficient and robust sparse preconditioner that is based on a direct factorization scheme for sparse matrices arising from the finite‐element discretization of elliptic partial differential equations. We use a fast (but approximate) multifrontal approach as a preconditioner and use an iterative scheme to achieve a desired accuracy. This approach combines the advantages of direct and iterative schemes to arrive at a fast, robust, and accurate preconditioner. We will show that this approach is faster (～2×) and more memory efficient (～2–3×) than a conventional direct multifrontal approach. Furthermore, we will demonstrate that this preconditioner is both faster and more effective than other preconditioners such as the incomplete LU preconditioner. Specific speedups depend on the matrix size and improve as the size of the matrix increases. The preconditioner can be applied to both structured and unstructured meshes in a similar manner. We build on our previous work and utilize the fact that dense frontal and update matrices, in the multifrontal algorithm, can be represented as hierarchically off‐diagonal low‐rank matrices. Using this idea, we replace all large dense matrix operations in the multifrontal elimination process with O(N) hierarchically off‐diagonal low‐rank operations to arrive at a faster and more memory efficient factorization scheme. We then use this direct factorization method at low accuracies as a preconditioner and apply it to various real‐life engineering test cases. Copyright © 2016 John Wiley & Sons, Ltd.     

Advances in piezoelectric thin films for acoustic biosensors,acoustofluidics and lab-on-chip applications

Recently, piezoelectric thin films including zinc oxide (ZnO) and aluminium nitride (AlN) have found a broad range of lab-on-chip applications such as biosensing, particle/cell concentrating, sorting/patterning, pumping, mixing, nebulisation and jetting. Integrated acoustic wave sensing/microfluidic devices have been fabricated by depositing these piezoelectric films onto a number of substrates such as silicon, ceramics, diamond, quartz, glass, and more recently also polymer, metallic foils and bendable glass/silicon for making flexible devices. Such thin film acoustic wave devices have great potential for implementing integrated, disposable, or bendable/flexible lab-on-a-chip devices into various sensing and actuating applications. This paper discusses the recent development in engineering high performance piezoelectric thin films, and highlights the critical issues such as film deposition, MEMS processing techniques, control of deposition/processing parametres, film texture, doping, dispersion effects, film stress, multilayer design, electrode materials/designs and substrate selections. Finally, advances in using thin film devices for lab-on-chip applications are summarised and future development trends are identified.