蚁群算法在服务器集群批量任务调度中的应用

服务器集群中的负载均衡和作业调度是影响系统性能的重要因素.本文描述服务器集群批量任务的作业调度问题,对该问题建立了基于图的模型.由于使用一般的启发式算法或动态规划算法解决该问题具有局限性,本文引入蚁群算法进行求解,并针对该问题具体求解提出了启发式距离合适的计算方法.最后在仿真的基础上,讨论了算法的优化效果和收敛性,结果表明蚁群算法解决该问题具有优异的性能.     

战时装备维修保障力量优化调度问题研究

战时装备维修保障力量优化调度对于提高维修效率具有重要意义。针对目前研究存在的优化目标单一、约束条件简单等不足,建立了维修保障力量优化调度的双层规划模型。为了便于问题的结构化求解,依据战时维修保障需求的特点,将其分解为具有主从递阶层次结构的子优化问题,并设计了问题求解的遗传算法。用实例对该方法进行了验证。实验结果表明该方法能够有效解决维修保障力量优化调度问题,由其生成的调度方案可操作性强,具有较好的军事应用价值。     

抢修任务多目标动态调度的动态驱动策略研究

抢修任务多目标动态调度能够有效解决“战时损伤装备不断出现,而抢修时间与抢修力量有限”这一突出矛盾,但由于新抢修需求的出现时刻具有不确定性,采用现有的时间(或数量)分批驱动策略,会导致抢修力量不能对新抢修需求进行及时响应、抢修力量出现闲置、抢修效益降低。为解决该问题,开展了战时抢修任务多目标动态调度的动态驱动策略研究。提出了抢修任务多目标动态调度问题及其总体求解思路。设计了基于抢修需求信息和抢修组状态的2种动态驱动策略,提出了一种新的动态驱动策略“混合分批+基于抢修组状态”。采用均匀设计思想,构造了6组测试问题实例,并通过实验分析了在多种因素共同影响的情况下,3种动态驱动策略的优劣性及适用性。仿真结果表明：与其它动态驱动策略相较,新的动态驱动策略“混合分批+基于抢修组状态”具有明显的优越性。     

考虑失效路段恢复的动态应急资源车辆调度模型

重大灾害救援中,应急资源车辆调度时常因某些道路毁损（通行功能失效）而绕行,相对延长了调度时间。基于现实可行性和必要性,将抢修失效路段与资源调度联为二级递阶系统,并考虑车辆行驶时间的动态性,建立了数学模型,同步规划道路恢复和车辆路径,为有效提升救援效率提供了新的途径。设计了双层基于启发式算法的求解策略,作为模型的直接应用和说明,最后的算例验证了模型和算法的合理性和可行性。     

敏捷供应链插单调度优化的启发式算法

针对在敏捷供应链已有生产计划基础上进行的插单调度问题,以单工厂和多供应商组成的两级供应链系统为研究对象,采用时间槽表示可用调度时间,以最小化供应链总成本为目标,建立了调度优化问题的整数规划(IP)模型,设计了求解该模型的逐批选优启发式(OOSH)算法。通过算例将其与距离优先和作业周期优先决策算法比较,验证了启发式算法的有效性,显示了敏捷供应链协同调度可以有效提高供应链的市场竞争力。     

面向存储资源优化的遥感卫星任务规划算法

针对遥感卫星的成像任务规划问题,按照任务重要性的不同,提出了两阶段调度策略,并设计了两个时间窗口选择规则。以星上存储资源优化为目标,利用地面站的下传活动将整个规划过程分为较小的调度区间,提出了可用存储空间上界估计算法计算每个调度区间的可调度存储资源容量,以此为基础对问题进行了简化,并给出了基于规则的启发式求解算法。实验结果表明,该算法是有效的。     

侦察卫星探测资源调度研究

侦察卫星探测资源调度是一类基于约束满足的优化问题。对卫星探测资源和探测任务的特点进行分析,在此基础上构建卫星探测资源调度的目标函数和约束条件,利用约束满足问题的建模思想对该调度问题进行建模。针对约束满足模型规模大、求解复杂的情况,结合卫星探测资源调度问题的特征,提出一种基于启发式禁忌搜索算法的模型求解方法,并通过仿真算例进行说明与分析。该调度模型和算法充分考虑了星载资源与对应任务的特点,尽量回避假设与简化条件的提出,具有较好的适用性,将为侦察与预警卫星网络任务规划与资源调度的研究奠定基础。     

基于柔性维护的堕化单机系统调度研究

针对单机系统,在假设生产系统为堕化系统,且生产过程中作业的加工不可中断的情况下,对考虑柔性时间窗口[uv]下进行长度为w的周期预防性维护的调度问题进行了研究。建立了综合考虑生产调度和设备维护的混合整数规划模型,并设计了一套基于贪婪的启发式算法对所研究问题进行优化求解。通过Cplex和启发式算法求解结果的对比证明了算法可以快速、有效地解决此类问题。     

自动化码头双小车岸桥与AGV协调调度问题研究

为研究自动化集装箱码头中自动导引运输车（Automated Guided Vehicle，AGV）与双小车岸桥（Double-Trolley Quay Crane，QC）的协调调度问题，考虑双小车岸桥中转平台及其容量限制，并以双小车岸桥门架小车时间窗为约束，建立以集装箱任务最大完工时间最小化为目标的混合整数规划模型。设计启发式算法，由中转平台的容量求得岸桥门架小车操作集装箱任务的时间窗，并采用遗传算法进行求解，给出相应的AGV调度优化方案，解决两大设备的协调调度问题。最后，以10组实验为例，比较了遗传算法与粒子群算法的优化结果。结果表明两种算法一致，且基于遗传算法的模型求解收敛速度更快，从而验证了该算法的可行性。     

效率异质型员工项目调度算法研究

研究了员工具有异质效率、最小化项目工期的项目调度问题,并建立了相应的整数线性规划模型。为解决此NP-hard问题,提出了基于优先规则的启发式算法,其在每次迭代中根据优先约束和优先规则选择优先任务员工对以分配任务,直至所有任务都完成调度。通过应用启发式算法生成初始调度,选用交换邻域结构和插入邻域结构产生邻域调度,并使用改进的前向递归算法求解目标函数值,构造出混合模拟退火算法。数值实验显示该算法能快速准确地进行寻优。     

A comparative evaluation of in-vehicle side view displays layouts in critical lane changing situation

Abstract

This study conducted a driving simulator experiment to comparatively evaluate three in-vehicle side view displays layouts for camera monitor systems (CMS) and the traditional side view mirror arrangement. The three layouts placed two electronic side view displays near the traditional mirrors positions, on the dashboard at each side of the steering wheel and on the centre fascia with the two displays joined side-by-side, respectively. Twenty-two participants performed a time- and safety-critical driving task that required rapidly gaining situation awareness through the side view displays/mirrors and making a lane change to avoid collision. The dependent variables were eye-off-the-road time, response time, and, ratings of perceived workload, preference and perceived safety. Overall, the layout placing the side view displays on the dashboard at each side of the steering wheel was found to be the best. The results indicated that reducing eye gaze travel distance and maintaining compatibility were both important for the design of CMS displays layout.

Practitioner Summary: A driving simulator study was conducted to comparatively evaluate three in-vehicle side view displays layouts for camera monitor systems (CMS) and the traditional side view mirror arrangement in critical lane changing situation. Reducing eye movement and maintaining compatibility were found to be both important for the ergonomics design of CMS displays layout.     

A Random Sampling O(n) Force‐calculation Algorithm for Graph Layouts

This paper proposes a linear‐time repulsive‐force‐calculation algorithm with sub‐linear auxiliary space requirements, achieving an asymptotic improvement over the Barnes‐Hut and Fast Multipole Method force‐calculation algorithms. The algorithm, named random vertex sampling (RVS), achieves its speed by updating a random sample of vertices at each iteration, each with a random sample of repulsive forces. This paper also proposes a combination algorithm that uses RVS to derive an initial layout and then applies Barnes‐Hut to refine the layout. An evaluation of RVS and the combination algorithm compares their speed and quality on 109 graphs against a Barnes‐Hut layout algorithm. The RVS algorithm performs up to 6.1 times faster on the tested graphs while maintaining comparable layout quality. The combination algorithm also performs faster than Barnes‐Hut, but produces layouts that are more symmetric than using RVS alone. Data and code: https://osf.io/nb7m8/     

基于最小二乘法的室内三维定位算法研究

现如今,室内位置服务成为国内外科研人员共同关注的焦点,人们对于位置服务的需求逐渐由最初的室外定位转变为室内定位,同时诸多的室内定位技术得以快速发展。通过以超宽带(UWB)的通信方式为依托,借助到达时间差值(TDOA)的定位模型,着重分析了最小二乘法在求解三维定位坐标时精度误差产生的主要原因。针对传统的最小二乘定位算法在求解三维定位坐标时,由于基站几何布局所引起的定位精度问题,提出基于最小二乘法的三维定位优化算法。通过对实验结果进行分析,比较定位算法在优化前后的两种场景下定位的不同表现效果,发现优化后的最小二乘定位算法的三维定位精度得以明显提高且定位效果稳定,同时也降低了三维定位精度对于基站几何布局的依赖性。     

A spatial scheduling system and its application to shipbuilding: DAS-CURVE

Spatial scheduling considers not only traditional scheduling constraints like resource capacity and due dates, but also dynamic spatial layout of the objects. Automation of spatial scheduling is particularly important when the spatial resources are critical bottleneck resources, as is the case in the shipbuilding industry. To develop a spatial scheduling expert system for shipbuilding, a methodology for spatial layout of polygonal objects within rectangular plates is first developed. This study is then extended to the methodology for spatial scheduling, including the time dimension. The methodology is applied to the scheduling of Daewoo shipbuilding to build a system DAS-CURVE. DAS-CURVE is successfully operational and its experimental performance is remarkable.     

Visualizing changes of hierarchical data using treemaps

While the treemap is a popular method for visualizing hierarchical data, it is often difficult for users to track layout and attribute changes when the data evolve over time. When viewing the treemaps side by side or back and forth, there exist several problems that can prevent viewers from performing effective comparisons. Those problems include abrupt layout changes, a lack of prominent visual patterns to represent layouts, and a lack of direct contrast to highlight differences. In this paper, we present strategies to visualize changes of hierarchical data using treemaps. A new treemap layout algorithm is presented to reduce abrupt layout changes and produce consistent visual patterns. Techniques are proposed to effectively visualize the difference and contrast between two treemap snapshots in terms of the map items' colors, sizes, and positions. Experimental data show that our algorithm can achieve a good balance in maintaining a treemap's stability, continuity, readability, and average aspect ratio. A software tool is created to compare treemaps and generate the visualizations. User studies show that the users can better understand the changes in the hierarchy and layout, and more quickly notice the color and size differences using our method.     

A real-time vision module for interactive perceptual agents

Abstract. Interactive robotics demands real-time visual information about the environment. Real-time vision processing, however, places a heavy load on the robot's limited resources, which must accommodate multiple other processes running simultaneously. This paper describes a vision module capable of providing real-time information from ten or more operators while maintaining at least a 20-Hz frame rate and leaving sufficient processor time for a robot's other capabilities. The vision module uses a probabilistic scheduling algorithm to ensure both timely information flow and a fast frame capture. In addition, it tightly integrates the vision operators with control of a pan-tilt-zoom camera. The vision module makes its information available to other modules in the robot architecture through a shared memory structure. The information provided by the vision module includes the operator information along with a time stamp indicating information relevance. Because of this design, our robots are able to react in a timely manner to a wide variety of visual events.     

基于坐标变换的图形自适应排列算法

为了解决基于网格技术的图形排列算法在处理可变尺寸图形排列问题上的局限性,基于几何变换思想,建立了有界平面上图形自适应排列的数学模型,并证明了其正确性,进而提出了基于坐标变换的图形自适应排列算法。此算法用图形平移变换方式代替网格划分方法在有界视图上部署图形元素,其时间复杂性为O(N)。最后将所获得的算法应用到面向中央空调节能控制的软PLC系统上,基于9类指令图形、3类测试案例的测试结果表明：本文算法能以较低的CPU占用率实现图形有序排列的效果,具有较高的运行速率与稳定性。     

Utilizing unreliable public resources for higher profit and better SLA compliance in computing utilities

Computing utilities are emerging as an important part of the infrastructure for outsourcing computer services. Fundamental to outsourcing is the notion of quality of service, which is defined by service level agreements (SLAs) between the computing utilities and clients. One of the major objectives of computing utilities is to maximize their net profit while maintaining customer loyalty. To achieve this objective, the computing utilities should meet or exceed their SLA constraints most of the time. Defining the SLAs conservatively might be one way of easily achieving these goals. However, by tuning the SLA parameters conservatively the computing utility might under utilize its resources with a resultant loss of revenue. Therefore, we can see two main issues with SLA management: designing SLAs competitively so that expected revenue for the computing utility is maximized and maintaining the operating conditions such that SLAs are satisfied with very high probability. In this paper, we show that inducting unreliable public resources into a computing utility enables more competitive SLAs while maintaining higher levels of run time compliances as well as maximizing profit. Our scheduling algorithms assume that idle cycles from public resources are available in plenty, therefore, the performance gains do not incur any additional financial cost. However, there is communication overhead when public resources from a wide area network is included. This overhead is kept to the minimum by enabling the scheduler work without any monitoring on the public resources.     

A granularity model for balancing the structural complexity of manufacturing systems equipment and layout

The structural complexity of a manufacturing system results primarily from the complexity of its equipment and their layout. The balance between both complexity sources can be achieved by searching for the best system granularity level, which yields a manufacturing system with the least overall structural complexity. A new system granularity complexity index is developed to sum up and normalize the complexity resulting from the system layout complexity and the equipment structural complexity. A previously developed layout complexity index together with a code-based structural complexity assessment are used to determine the structural complexity of standalone pieces of equipment and to arrive at a balance between the two sources of complexity. Cladistics analysis is used to hierarchically cluster required pieces of equipment and bundle them into more integrated equipment and machines and demonstrate the possible different system granularity levels. The new developed model is a useful tool to create specific system configuration and layout alternatives based on system components adjacency, and then select the system design with the least overall structural complexity among those alternatives. The results of the presented case study clearly demonstrated this trade-off where decomposing manufacturing systems into a highly granular configuration with standalone machines maximizes system layout complexity and minimizes equipment complexity, while at a low level of granularity pieces of equipment are bundled into complex integrated machines, lines or cells but with a very simple system layout.     

Coherent time-varying graph drawing with multifocus+context interaction

We present a new approach for time-varying graph drawing that achieves both spatiotemporal coherence and multifocus+context visualization in a single framework. Our approach utilizes existing graph layout algorithms to produce the initial graph layout, and formulates the problem of generating coherent time-varying graph visualization with the focus+context capability as a specially tailored deformation optimization problem. We adopt the concept of the super graph to maintain spatiotemporal coherence and further balance the needs for aesthetic quality and dynamic stability when interacting with time-varying graphs through focus+context visualization. Our method is particularly useful for multifocus+context visualization of time-varying graphs where we can preserve the mental map by preventing nodes in the focus from undergoing abrupt changes in size and location in the time sequence. Experiments demonstrate that our method strikes a good balance between maintaining spatiotemporal coherence and accentuating visual foci, thus providing a more engaging viewing experience for the users.