Decision diagrams for solving traveling salesman problems with pickup and delivery in real time

The Traveling Salesman Problem with Pickup and Delivery seeks a minimum cost path with pickups preceding deliveries. It is important in on-demand last-mile logistics, such as ride sharing and meal delivery. We examine the use of low-width Decision Diagrams in a branch-and-bound with and without Assignment Problem inference duals as a primal heuristic for finding good solutions within strict time budgets. We show these diagrams can be more effective than similarly structured hybrid Constraint Programming techniques for real-time decision making.     

Developing Systems for Real-Time Streaming Analysis

Sources of streaming data are proliferating and so are the demands to analyze and mine such data in real time. Statistical methods frequently form the core of real-time analysis, and therefore, statisticians increasingly encounter the challenges and implicit requirements of real-time systems. This work recommends a comprehensive strategy for development and implementation of streaming algorithms, beginning with exploratory data analysis in a flexible computing environment, leading to specification of a computational algorithm for the streaming setting and its initial implementation, and culminating in successive improvements to computational efficiency and throughput. This sequential development relies on a collaboration between statisticians, domain scientists, and the computer engineers developing the real-time system. This article illustrates the process in the context of a radio astronomy challenge to mitigate adverse impacts of radio frequency interference (noise) in searches for high-energy impulses from distant sources. The radio astronomy application motivates discussion of system design, code optimization, and the use of hardware accelerators such as graphics processing units, field-programmable gate arrays, and IBM Cell processors. Supplementary materials, available online, detail the computing systems typically used for streaming systems with real-time constraints and the process of optimizing code for high efficiency and throughput.     

Temperature‐dependent local atomic structures in the traditional Fe65Ni35 Invar alloy by X‐ray fluorescence holography

Fe and Ni Kα X‐ray fluorescence holography measurements were conducted on a single crystal Fe₆₅Ni₃₅ Invar alloy at 100 and 300 K to investigate the temperature dependence of the 3‐dimensional local structures around the Fe and Ni atoms, respectively. Local structural information was obtained by detailed analyses using a L₁‐regularized linear regression for the experimental data. At 100 K, the local atomic arrangements around both the elements show fcc structures. At 300 K, however, only the image around Fe shows a bcc‐like neighboring arrangement. From these X‐ray fluorescence holography data, we propose a model that with increasing temperature, an Fe atom with the low‐spin state enters at the central position of the fcc lattice and is stabilized. And then, large angular positional fluctuations are induced for the atoms at the face‐centered positions around the central Fe atom only.     

Preparation and fabrication of porous-Fe2O3/carbon black nanocomposite: a portable electrochemical sensor for psychotropic drug detection in environmental samples

Herein, we reported the fabrication of porous iron oxide/carbon black (P–Fe₂O₃/CB) composite through a two-step engineering method. At first, Prussian blue microcubes were used as a precursor and further calcined to form P–Fe₂O₃ microcubes. The intercalation of CB nanoparticles with P–Fe₂O₃ nanocubes was processed through the ultrasonication method. The obtained P–Fe₂O₃/CB were successfully scrutinized through various physiochemical characterization methods. The proposed P–Fe₂O₃/CB-modified glassy carbon electrode sensor was successfully implemented in the electrochemical sensing of chlorpromazine hydrochloride due to its very low charge transfer resistance (R_ct) compared to the other electrode modifiers. The sensitive detection of CPMH through differential pulse voltammetry exemplifies an excellent electroanalytical performance such as a wide linear range of 0.5–1472 μM, a lower detection limit (0.001 μM), and an appraisable sensitivity of 1.99 μA/μM cm^?2 due to its availability of a high number of active sites and its large surface area, respectively. It also expresses excellent selectivity, repeatability, reproducibility, and stability results. Moreover, the practical feasibility of the as-fabricated P–Fe₂O₃/CB/glassy carbon electrode sensor shows exquisite recovery (98.1–100.8%) results with an appraisable current response in various biological, pharmaceutical, and environmental samples.     

A simulation method of aircraft plumes for real-time imaging

Real-time infrared simulation technology can provide a large number of infrared images under different conditions to support the design, test and evaluation of a system having infrared imaging equipment with very low costs. By synthesizing heat transfer, infrared physics, fluid mechanics and computer graphics, a real-time infrared simulation method is proposed based on the method of characteristics to predict the infrared feature of aircraft plumes, which tries to obtain a good balance between simulation precision and computation efficiency. The temperature and pressure distribution in the under-expansion status can be rapidly solved with dynamically changing flight statuses and engine working states. And a modified C–G (Curtis–Godson) spectral band model that combines the plume streamlines with the conventional C–G spectral band model was implemented to calculate the non-uniformly distributed radiation parameters inside a plume field. The simulation result was analyzed and compared with the CFD++, which validates the credibility and efficiency of the proposed simulation method.     

基于多模差分融合的高速车辆定位算法

针对车辆高速运动下定位延时大、精度低、稳定性差的问题,发挥GPS、RSSI和INS三种定位模式的各自优势,将GPS差分校准算法与RSSI测距相结合求解横坐标,将RSSI测距与INS惯导迭代算法相结合求解纵坐标,提出了一种适合高速运动车辆的多模差分融合精确定位算法。以四车道的高速路为场景进行了仿真实验,当车速为70km/h时,跟踪误差<1m,定位延时<0.2s。实验结果表明,该算法可实现车身级和车道级定位,在精确交通诱导、车辆防撞等智能交通领域具有应用前景和推广价值。     

基于LabVIEW的水下航行器 航行控制系统通信模块设计

为了保证水下航行器的航行安全,航行控制系统内部通信和航行系统与综合控制台之间的通信的性能需要具有较高的实时性和可靠性。本文基于以太网搭建系统,详细地介绍了系统通信的组成和传输数据的类型,结合系统要求以及TCP/IP、UDP通信协议的特点,选取合适的协议和数据传递方式;对于出现通信堵塞和数据包丢失以及链路不稳定情况,采取自动重连和数据自动重发机制;并采用图形化软件LabVIEW的封装函数实现数据的收发和保存,借助LabVIEW和C语言混合编程实现数据的高效处理;在实验室搭建半实物仿真平台进行测试,结果表明,航行控制系统内部以及和综合控制台之间的数据传输准确、可靠。     

稀有气体卤化物准分子激光器工作气体实时补给技术

为延长稀有气体卤化物准分子激光器工作气体使用寿命,在原有供气设备基础上增加了工作气体实时补给技术.该技术采用FPGA控制系统将逐步提高放电电压、补充卤素气体和更换部分混合气体等操作有效组合起来.随着激光脉冲能量的下降,逐步提高放电电压;当放电电压达到最大值时,开始补充卤素气体,并恢复放电电压;当补充卤素气体效果不明显时,更换部分混合工作气体.将该技术应用于医用型ArF准分子激光器中进行实验研究,结果表明:在没有使用工作气体实时补给技术的情况下,激光器累计工作14.38 h后,输出单脉冲激光能量下降了17.2％;采用工作气体实时补给技术后,激光器输出能量下降速率明显降低,累计工作14.38 h,其单脉冲能量下降率能控制在3％范围内.因此,采用该技术可延长激光器工作气体的使用寿命、提高输出激光能量稳定性、减少停机次数并降低运行成本.     

基于瑞利-索末菲积分的大衍射角衍射光学元件设计方法

针对现有的衍射光学元件设计方法只适用于小角度衍射的情况,本文提出了一种基于瑞利-索末菲衍射积分的设计方法,可以用来设计具有大衍射角的衍射光学元件。先对目标光场进行坐标变换和强度调整,再利用改进的Gerchberg-Saxton算法优化得到衍射光学元件的相位分布。分别采用本文方法和原有的基于夫琅禾费衍射积分的方法设计衍射光学元件实现线条结构光和不同角度方框图形的光场重构,结果表明:原有的设计方法只适用于衍射角全角小于25°的情况,当衍射角大于25°时,重构光场会出现显著的枕形畸变和不均匀的强度分布。而本文方法在小角度和大角度衍射下都能重构出准确的衍射角和较为均匀的强度分布.     

Engineered pixels using active plasmonic holograms with liquid crystals

Digital holography requires arrays of small reconfigurable elements to achieve complex reconstruction of the hologram with common systems based on pixels utilizing liquid crystal on silicon (LCoS) technology. The backplane of a typical pixel element is potentially underutilized and thus relatively large physical areas exist in which information can be stored and exploited to give additional functionality to pixel elements. Polarisation and wavelength dependent optical properties can be achieved in small areas using the plasmonic effects of optical antennae. The integration of LCs with optical antennae‐based plasmonic holograms allows active modulation of the far field pattern. The work here demonstrates the concept that conventional LCoS pixel elements can be greatly enhanced with the integration of plasmonic holograms, composed of optical antennae patterned on the surface, giving rise to new levels of modulation capability for holographic pixel elements. Using LCs, polarisation dependent effects in plasmonic holograms can be switched. ‘Engineered pixels', with sub‐wavelength multiplexing over both polarisation and wavelength, can increase the channel capacity of a typical LC display device. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)