The min–max split delivery multi-depot vehicle routing problem with minimum service time requirement

The min–max Split Delivery Multi-Depot Vehicle Routing Problem with Minimum Service Time Requirement (min–max SDMDVRP-MSTR) is a variant of the Multi-Depot Vehicle Routing Problem. Each customer requires a specified amount of service time. The service time can be split among vehicles as long as each vehicle spends a minimum amount of service time at a customer. The objective is to minimize the duration of the longest route (where duration is the sum of travel and service times).We develop a heuristic (denoted by MDS) that solves the min–max SDMDVRP-MSTR in three stages: (1) initialize a feasible solution without splits; (2) improve the longest routes by splitting service times; (3) ensure all minimum service time requirements are satisfied. The first stage of MDS is compared to an existing heuristic to solve the min–max Multi-Depot Vehicle Routing Problem on 43 benchmark instances. MDS produces 37 best-known solutions. We also demonstrate the effectiveness of MDS on 21 new instances whose (near) optimal solutions can be estimated based on geometry. Finally, we investigate the savings from split service and the split patterns as we vary the required service times, the average number of customers per route, and the minimum service time requirement.     

Sub 0.5-V bulk-driven LTA in 0.18 μm CMOS

The paper deals with a new solution for an ultra-low-voltage loser take all (LTA) circuit, capable to operate from supply voltages ranging from 0.3 to 0.5 V. The proposed circuit exploit the idea of multiple voltage buffers with a common output. In order to obtain a compact and precise LTA, a new kind of an ultra-low-voltage buffer has been developed. Owing to the fact that for such a low supply voltage the available voltage swing is highly reduced, the impact of transistor mismatches and speed-accuracy-power tradeoffs have extensively been discussed in the paper. While implemented in a standard 0.18 μm CMOS process, the proposed LTA circuit in a two-input version consumes 3.0 μW from a 0.5 V supply and provides 10 μs crossover recovery time for a 1 pF load capacitance.     

电气系统的优化对轧材生产的影响

本文主要探讨电气控制系统对轧钢的影响，通过对电气系统的优化，改善活套、微张力的控制，提高小规格材的成品率。     

阻尼柔性连接TMD的最优动力特性

本文研究了阻尼柔性连接TMD在控制结构地震反应时的最优动力特性。基于导出的设置阻尼柔性连接TMD结构位移传递函数，建立了结构的动力放大系数（DMF）设计公式。于是TMD的优化准则可选为：最大动力放大系数中最小值的最小化（Min.Min.Max.DMF)。通过最优搜寻得不同刚度比R时TMD最优调谐频率比、最优阻尼比和相应的Min.Min.Max.DMF。为比较，阻尼刚性连接（R＝0）的TMD也被考虑。数值结果表明，阻尼柔性连接TMD的刚性比R最好取为0.5。因此，目前的研究拓宽了TMD的应用范围。     

Low power current-mode binary-tree asynchronous Min/Max circuit

A novel, current-mode, binary-tree, asynchronous Min/Max circuit for application in nonlinear filters as well as in analog artificial neural networks is proposed. The relatively high precision above 99% can be achieved by eliminating the copying of the input signals from one layer to the other in the tree. In the proposed solution, the input signals are always directly copied to particular layers using separate signal paths. This makes the precision almost independent on the number of the layers i.e. the number of the inputs. The circuit is a flexible solution. The power dissipation, as well as data rate can be scaled up and down in a wide range. For an average value of the input currents of 20 μA and data rate of 11 MHz the circuit dissipates 505 μW, while for the signals of 200 nA and data rate of 500 kHz the power dissipation is reduced to 1 μW. The prototype circuit with four inputs, realized in the CMOS 0.18 μm technology, occupies the area of 1800 μm².     

基于总体方差最小消去DCT的方块效应

提出基于总体方差最小消去离散余弦变换DCT的方块效应,推导出水平集方程,用最小/最大曲率流替代水平集中的平均曲率流。该方法在平滑噪声和消去方块效应的同时,能保留图像的主要结构特征。后续分割实验结果表明,该方法比均值滤波后的图像有更好的视觉和分割效果。     

Optimizing spatial Min/Max aggregations

Aggregate computation over a collection of spatial objects appears in many real-life applications. Aggregates are computed on values (weights) associated with spatial objects, for example, the temperature or rainfall over the area covered by the object. In this paper we concentrate on MIN/MAX aggregations: given a query rectangle, find the minimum/maximum weight among all objects intersecting the query rectangle. Traditionally such queries have been performed as range searches. Assuming that objects are indexed by a spatial access method (SAM), the MIN/MAX is computed while retrieving those objects intersecting the query interval. This requires effort proportional to the number of objects satisfying the query, which may be large. A better approach is to maintain aggregate information among the index nodes of the spatial access method; then various index paths can be eliminated during the range search. Yet another approach is to build a specialized index that maintains the aggregate incrementally. We propose four novel optimizations for improving the performance of MIN/MAX queries when an index structure (traditional or specialized) is present. Moreover, we introduce the MR-tree, an R-tree-like dynamic specialized index that incorporates all four optimizations. Our experiments show that the MR-tree offers drastic performance improvement over previous solutions. As a byproduct of this work we present an optimized version of the MSB-tree, an index that has been proposed for the MIN/MAX computation over 1D interval objects.Received: 5 September 2003, Published online: 24 February 2005Edited by: T. ÖzsuVassilis J. Tsotras: This research was supported by NSF Grants IIS-9907477, EIA-9983445, and IIS-0070135 and by the Department of Defense. Correspondence to: D. Zhang     

基于Kanai-Tajimi/Clough-Penzien模型时MTMD的动力特性

研究了由许多刚度和经保持常量且频率呈线性分布的TMD形成的MTMD的地震特性，基于虚拟激励法和Kanai-Tajimi及Clough-Penzien地震谱，建立了结构－MTMD系统的传递函数和动力放大系数（DMF），于是MTMD的优化准则定义为Min.Min.Max.DMF。通过最优搜寻得MTMD的最优频率间隔，平均阻尼比，调谐频率比和相应的控制有效性指标，考虑结构受控频率与场地上卓越频率比的不同取值，研究场地上卓越频率对MTMD最优参数及有效性的影响。     

面向专色工艺的彩色图像分色及印制方法

提出了一种面向专色工艺的彩色图像分色及印制方法.该方法根据印制图像的颜色和油墨信息,通过遗传算法选择用以印制图像的油墨种类,采用数值优化算法解决定制油墨的图像分色问题.该方法能以较少种类油墨的印制出与传统印制结果同等或更为鲜明逼真的图像,可广泛应用于印刷、印染、陶瓷印花等行业.     

An efficient implementation of the Min-Min heuristic

Min—Min is a popular heuristic for scheduling tasks to heterogeneous computational resources, which has been applied either directly or as part of more sophisticated heuristics. However, for large scenarios such as grid computing platforms, the time complexity of a straightforward implementation of Min—Min, which is quadratic in the number of tasks, may be prohibitive. This has motivated the development of high performance computing (HPC) implementations, and the use of simpler heuristics for the sake of acceptable execution times. We propose a simple algorithm that implements Min—Min requiring only O(mn) operations for scheduling n tasks on m machines. Our experiments show, in practice, that a straightforward sequential implementation of this algorithm significantly outperforms other state of the art implementations of Min—Min, even compared to HPC implementations. In addition, the proposed algorithm is at least as suitable for parallelization as a direct implementation of Min—Min.