Solving a multi-level capacitated lot sizing problem with multi-period setup carry-over via a fix-and-optimize heuristic

This paper presents a new algorithm for the dynamic multi-level capacitated lot sizing problem with setup carry-overs (MLCLSP-L). The MLCLSP-L is a big-bucket model that allows the production of any number of products within a period, but it incorporates partial sequencing of the production orders in the sense that the first and the last products produced in a period are determined by the model. We solve a model which is applicable to general bill-of-material structures and which includes minimum lead times of one period and multi-period setup carry-overs. Our algorithm solves a series of mixed-integer linear programs in an iterative so-called fix-and-optimize approach. In each instance of these mixed-integer linear programs a large number of binary setup variables is fixed whereas only a small subset of these variables is optimized, together with the complete set of the inventory and lot size variables. A numerical study shows that the algorithm provides high-quality results and that the computational effort is moderate.     

An efficient optimal algorithm for the quantity discount problem in material requirement planning

An optimal algorithm based on branch-and-bound approach is presented in this paper to determine lot sizes for a single item in material requirement planning environments with deterministic time-phased demand and constant ordering cost with zero lead time, where all-units discounts are available from vendors and backlog is not permitted. On the basis of the proven properties of optimal order policy, a tree-search procedure is presented to construct the sequence of optimal orders. Some useful fathom rules have been proven, which make the algorithm very efficient. To compare the performance of this algorithm with the other existing optimal algorithms, an experimental design with various environments has been developed. Experimental results show that the performance of our optimal algorithm is much better than the performance of other existing optimal algorithms. Considering computational time as the performance measure, this algorithm is considered the best among the existing optimal algorithms for real problems with large dimensions (i.e. large number of periods and discount levels).     

Bottleneck flows in unit capacity networks

The bottleneck network flow problem (BNFP) is a generalization of several well-studied bottleneck problems such as the bottleneck transportation problem (BTP), bottleneck assignment problem (BAP), bottleneck path problem (BPP), and so on. The BNFP can easily be solved as a sequence of O(logn) maximum flow problems on almost unit capacity networks. We observe that this algorithm runs in O(min{m3/2,n2/3m}logn) time by showing that the maximum flow problem on an almost unit capacity graph can be solved in O(min{m3/2,n2/3m}) time. We then propose a faster algorithm to solve the unit capacity BNFP in time, an improvement by a factor of at least . For dense graphs, the improvement is by a factor of . On unit capacity simple graphs, we show that BNFP can be solved in time, an improvement by a factor of . As a consequence we have an algorithm for the BTP with unit arc capacities.     

基于GPU的遥感影像数据融合IHS变换算法

提出基于图形处理单元（GPU）的遥感影像IHS融合算法,利用图形硬件的可编程渲染器和其处理数据的并行性,把IHS的正反变换映射到GPU中进行计算。应用RTT和MRT技术实现IHS正反变换中3个分量的并行渲染输出,加速计算过程。实验结果表明,在数据量较大时,该算法的处理速度比基于CPU的算法速度更快。     

NTRU参数选择方法的研究

NTRU算法是一种基于环的公开密钥体制,与RSA和ECC等典型的加密算法相比,在安全性和速度方面具有明显的优势。分析目前比较成熟的攻击NTRU方法,从安全的角度,根据不同的应用场合,给出NTRU加密参数选择方法,减少选择NTRU参数的盲目性,达到提高算法的执行速度、减少占用系统资源的目的。     

Economic lot sizing in a production system with random demand

An extended economic production quantity model that copes with random demand is developed in this paper. A unique feature of the proposed study is the consideration of transient shortage during the production stage, which has not been explicitly analysed in existing literature. The considered costs include set-up cost for the batch production, inventory carrying cost during the production and depletion stages in one replenishment cycle, and shortage cost when demand cannot be satisfied from the shop floor immediately. Based on renewal reward process, a per-unit-time expected cost model is developed and analysed. Under some mild condition, it can be shown that the approximate cost function is convex. Computational experiments have demonstrated that the average reduction in total cost is significant when the proposed lot sizing policy is compared with those with deterministic demand.     

Nonlinear aircraft sensor fault reconstruction in the presence of disturbances validated by real flight data

This paper proposes an approach for Inertial Measurement Unit sensor fault reconstruction by exploiting a ground speed-based kinematic model of the aircraft flying in a rotating earth reference system. Two strategies for the validation of sensor fault reconstruction are presented: closed-loop validation and open-loop validation. Both strategies use the same kinematic model and a newly-developed Adaptive Two-Stage Extended Kalman Filter to estimate the states and faults of the aircraft. Simulation results demonstrate the effectiveness of the proposed approach compared to an approach using an airspeed-based kinematic model. Furthermore, the major contribution is that the proposed approach is validated using real flight test data including the presence of external disturbances such as turbulence. Three flight scenarios are selected to test the performance of the proposed approach. It is shown that the proposed approach is robust to model uncertainties, unmodeled dynamics and disturbances such as time-varying wind and turbulence. Therefore, the proposed approach can be incorporated into aircraft Fault Detection and Isolation systems to enhance the performance of the aircraft.     

基于RS485总线和ModBus RTU通讯协议的浆纱机速度监测系统

通过建立基于RS485总线和ModBus RTU协议的浆纱机速度监测系统,来实现浆纱机生产信息的管理汇总,有效地杜绝了值车工的不当操作,保障了浆纱机的正常运行,提高了织造的生产效率。     

求解圆盘图中最小连通支配集的近似算法

针对无线传感器网络常用的拓扑模型单位圆盘图,提出了基于分布式贪心策略的近似算法DDT,在算法执行的每一轮中,根据一跳邻域范围内的权值和邻居的状态信息,选举出节点并和已确定的节点连接,逐步构造出网络图中的一个支配树。用概率方法研究了支配树中的节点度的性质,通过对极大独立集和最小连通支配集之间关系的分析,得到单位圆盘图中最小连通支配集问题一个新的近似比。计算结果表明,和相关的分布式算法相比,DDT产生的连通支配集在规模上更优。     

基于通用分组无线业务短信控制的LED点阵屏设计

为满足中小商家的使用需求,给出了一种低成本、内容更新便捷的远程控制点阵LED文字显示屏的方案。该系统采用单片机(MCU)作为系统处理核心,采用 GPRS/GSM通信标准,通过显示屏上通用分组无线业务(GPRS)模块接收手机发送的控制命令及显示数据,经处理后控制LED显示屏的扫描显示,实现点阵屏远程更新显示内容。经一段时间的使用,系统运行稳定可靠,基本达到设计要求。