图形点阵液晶模块的中文菜单界面的实现

研究了基于DEM12864P图形点阵液晶模块实现中文菜单人机界面的问题。首先分析了液晶模块DEM12864P的特性,阐述了DDRAM寻址与液晶点阵的对应关系及中文字符、中文菜单在液晶模块上的显示规则,进而介绍了一种基于多任务背景的屏幕光标实现方法及菜单数据结构的设计,提出了相应软件设计的实现方法.     

Using stochastic programming to solve an outpatient appointment scheduling problem with random service and arrival times

We study a stochastic outpatient appointment scheduling problem (SOASP) in which we need to design a schedule and an adaptive rescheduling (i.e., resequencing or declining) policy for a set of patients. Each patient has a known type and associated probability distributions of random service duration and random arrival time. Finding a provably optimal solution to this problem requires solving a multistage stochastic mixed‐integer program (MSMIP) with a schedule optimization problem solved at each stage, determining the optimal rescheduling policy over the various random service durations and arrival times. In recognition that this MSMIP is intractable, we first consider a two‐stage model (TSM) that relaxes the nonanticipativity constraints of MSMIP and so yields a lower bound. Second, we derive a set of valid inequalities to strengthen and improve the solvability of the TSM formulation. Third, we obtain an upper bound for the MSMIP by solving the TSM under the feasible (and easily implementable) appointment order (AO) policy, which requires that patients are served in the order of their scheduled appointments, independent of their actual arrival times. Fourth, we propose a Monte Carlo approach to evaluate the relative gap between the MSMIP upper and lower bounds. Finally, in a series of numerical experiments, we show that these two bounds are very close in a wide range of SOASP instances, demonstrating the near‐optimality of the AO policy. We also identify parameter settings that result in a large gap in between these two bounds. Accordingly, we propose an alternative policy based on neighbor‐swapping. We demonstrate that this alternative policy leads to a much tighter upper bound and significantly shrinks the gap.     

SpaceFibre网络服务质量时隙资源分配算法

为保证SpaceFibre星载数据网络大量实时数据流的超高速确定性传输,提出一种包含两个子算法的SpaceFibre网络服务质量时隙资源分配算法。形式化描述网络服务质量机制,给出调度矩阵相关定义;创建网络服务质量排队模型,定量分析时隙资源分配对网络时延性能的影响;考虑网络兼容性和算法鲁棒性,给出改进二进制序列调度子算法;采用提高初始种群进化程度和增加遗传算子等方法,给出改进混合单亲遗传调度子算法;利用Opnet网络仿真平台建立网络服务质量仿真模型,对比不同算法下网络时延性能。仿真结果表明,该时隙资源分配算法与其他算法相比,网络平均延时降低,网络性能得到显著改善,对构建低延时SpaceFibre网络具有参考意义。     

GPS用于月球探测器轨道近地段导航

月球探测器轨道近地段飞行要求有精确的位置和速度信息。利用GPS的动力法解算能够提供必要的精度。文章给出了探测器近地段的GPS可见星条件及数目、动力法导航解算、不同采样周期和不同力模型对导航精度的影响。结果表明 ,采用简化力模型和 5s采样周期的动力法导航能够满足月球探测器近地段导航精度要求     

计算机人机交互界面的变化与计算机的发展

讨论人机交互界面性质设定变化对计算机发展的影响问题.认为人与计算机是通过一定界面进行信息交流的,而界面是否友好直接关系到计算机的应用及发展.及时改变人机交互界面的性质是计算机发展的关键.     

反电动势对无扰载荷航天器精确定向的影响

无扰载荷航天器中非接触式作动器反电动势会引起有效载荷模块与支持模块之间的耦合，影响有效载荷模块的精确定向性能。通过建立无扰载荷航天器的耦合动力学模型，分析非接触式作动器反电动势对有效载荷模块精确定向性能的影响。考虑六支杆立方构型无扰载荷接口，结合拉格朗日方程和牛顿欧拉方法建立有效载荷模块平台动力学模型。推导非接触式作动器的输出力模型，并引入有效载荷模块平台动力学模型，给出考虑非接触式作动器反电动势的耦合动力学模型。将支持模块上飞轮动静不平衡引起的谐振作为干扰力矩，建立了无扰载荷航天器在轨定向状态的Simulink仿真模型。仿真结果表明，反电动势系数越大，干扰力矩对有效载荷模块的影响越大，有效载荷模块精确定向精度越低。     

对接组合体初始姿态影响的建模研究

建立了对接过程对组合体初始姿态影响的解析与数值模型。解析模型采用相对于整体质心的动量矩定理,给出了对接完成后组合体姿态角速度计算的解析表达式。结合追踪器的绝对运动方程和目标器的相对运动方程,建立了基于对接动力学的数值模型。通过单一偏差和组合偏差两种算例,对解析和数值模型得到的组合体初始姿态角速度进行了对比分析。计算结果表明,两种模型绝对偏差在0.07°/s以内,相对偏差在10%以内,另外给出了两种模型在工程任务中各自的适用阶段。     

喷流干扰效应的快速计算方法

给出了一种快速计算火箭发动机喷流流场的方法,并在此基础上发展了一种计算喷流与物面间干扰流场及飞行器气动特性的工程计算方法。该方法不仅考虑了喷流与物面的碰撞,还考虑了有攻角下自由来流与喷流间的相互干扰。计算结果表明,该方法对飞行器初步设计是十分有用的工具     

Impacts of logistics information on sales: Evidence from Alibaba

Facing fierce competition from rivals, sellers in online marketplaces are eager to improve their sales by delivering items faster and more reliably. Because logistics quality can be known only after a transaction, sellers must identify effective ways to communicate logistics information to consumers. Drawing on the accessibility-diagnosticity framework, we theorize that the sales impacts of logistics information depend on its relative diagnostic value. Using data on 1493 items with 505,785 consumer reviews from an online marketplace, we examine how sales are affected by three information sources for logistics services: online word of mouth (WOM) about logistics, self-reported logistics services, and expected delivery time. We use an instrumental variable method to address the endogeneity issue between sales and WOM. We find that, ceteris paribus, consumers give more weight to WOM about logistics and delivery time when they make purchase decisions but less weight to self-reported logistics service. The effects of logistics information on sales are asymmetric for large and small sellers.     

空间飞行器及其推进系统智能自治控制技术分析

空间飞行器及其推进系统由于系统本身的复杂性、工作环境的不确定性和未知性等,利用传统的现代控制理论与方法对其进行控制十分困难。文中深入分析了智能自治控制系统内涵、功能及其构成框架,解析了空间飞行器RemoteAgent智能自治控制系统的基本构成,对空间飞行器推进系统重构问题进行了应用分析,对研究和发展我国空间飞行器的智能自治控制系统有一定的借鉴作用。