截幅效应对DMT调制的影响及一种减小截幅噪声的方法

ＤＭＴ（ＤｉｓｃｒｅｔｅＭｕｌｔｉｔｏｎｅ）调制是一种在ＡＤＳＬ（ＡｓｙｍｍｅｔｒｉｃａｌＤｉｇｉｔａｌＳｕｂｓｃｒｉｂｅＬｉｎｅ）中被广泛采用调制技术。本文分析了在ＤＭＴ中对信号进行截幅所产生的影响，计算了Ｄ／Ａ变换产生的量化噪声和截幅噪声，并与未截幅时相比较，在不降低ＳＮＲ的情况下，降低了Ｄ／Ａ变换器的精度的要求，并求出最佳截幅因子。本文分析了一种减小截幅噪声的方法，并说明在非最佳截幅时，通过这种方法可获得与最佳截幅同样的结果。     

考虑质心流动与偏移的通用弹道仿真模型

引入了质心坐标系的概念,对弹体坐标系的定义作了适当修正,给出了考虑质心流动与偏移的通用弹道仿真模型及相应的转动惯量与惯性积的计算公式     

战车火控系统软件可靠性的仿真测试平台

以平均无故障时间间隔(MTBF)和任务成功率为主指标,以某型坦克火控系统为载体,提出了战车非制导武器火控系统软件可靠性仿真测试平台的方案,并对其软件可靠性的仿真测试与验证技术进行了讨论.     

碳化硼涂覆的碳纤维的抗热氧化性研究

用自己合成的裂解能得到碳化硼的聚碳硼烷,对碳纤维进行涂层,并详细测试了涂层碳纤维的抗热氧化性能。     

高超声速滑翔飞行器变轨段自适应跟踪制导方法

针对高超声速滑翔飞行器变轨段大偏差条件下的标准轨迹跟踪问题,提出一种基于权值矩阵自适应修正的变轨段跟踪制导方法。分析了变轨段主要控制方式和标准轨迹特性;将简化的纵向运动方程在标准轨迹附近线性化;采用将误差项引进线性二次型性能指标加权矩阵的方式,设计了改进的权值自适应修正跟踪制导方法。CAV-H飞行器仿真分析表明,该方法能够实现高超声速滑翔飞行器变轨段高精度自适应跟踪制导,对初始及过程偏差具有良好的鲁棒性。     

Modeling and solution for the ship stowage planning problem of coils in the steel industry

We consider a ship stowage planning problem where steel coils with known destination ports are to be loaded onto a ship. The coils are to be stowed on the ship in rows. Due to their heavy weight and cylindrical shape, coils can be stowed in at most two levels. Different from stowage problems in previous studies, in this problem there are no fixed positions on the ship for the coils due to their different sizes. At a destination port, if a coil to be unloaded is not at a top position, those blocking it need to be shuffled. In addition, the stability of ship has to be maintained after unloading at each destination port. The objective for the stowage planning problem is to minimize a combination of ship instability throughout the entire voyage, the shuffles needed for unloading at the destination ports, and the dispersion of coils to be unloaded at the same destination port. We formulate the problem as a novel mixed integer linear programming model. Several valid inequalities are derived to help reducing solution time. A tabu search (TS) algorithm is developed for the problem with the initial solution generated using a construction heuristic. To evaluate the proposed TS algorithm, numerical experiments are carried out on problem instances of three different scales by comparing it with a model‐based decomposition heuristic, the classic TS algorithm, the particle swarm optimization algorithm, and the manual method used in practice. The results show that for small problems, the proposed algorithm can generate optimal solutions. For medium and large practical problems, the proposed algorithm outperforms other methods. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 564–581, 2015     

Bicriteria scheduling on a single batching machine with job transportation and deterioration considerations

We study a single batching machine scheduling problem with transportation and deterioration considerations arising from steel production. A set of jobs are transported, one at a time, by a vehicle from a holding area to the single batching machine. The machine can process several jobs simultaneously as a batch. The processing time of a job will increase if the duration from the time leaving the holding area to the start of its processing exceeds a given threshold. The time needed to process a batch is the longest of the job processing times in the batch. The problem is to determine the job sequence for transportation and the job batching for processing so as to minimize the makespan and the number of batches. We study four variations (P1, P2, P3, P4) of the problem with different treatments of the two criteria. We prove that all the four variations are strongly NP‐hard and further develop polynomial time algorithms for their special cases. For each of the first three variations, we propose a heuristic algorithm and analyze its worst‐case performance. For P4, which is to find the Pareto frontier, we provide a heuristic algorithm and an exact algorithm based on branch and bound. Computational experiments show that all the heuristic algorithms perform well on randomly generated problem instances, and the exact algorithm for P4 can obtain Pareto optimal schedules for small‐scale instances. © 2014 Wiley Periodicals, Inc. Naval Research Logistics 61: 269–285, 2014     

自由飘浮空间机器人准刚性分解运动轨迹控制与仿真

研究轨道空间机器人操作时,基座处于自由飘浮状态的手爪准刚性运动直角坐标轨迹的分解运动控制,重点分析了广义雅可比矩阵的计算,并进行了空间单手３—ＤＯＦ的仿真,该方法可相应推广到开链多手。     

阶比谱分析与汽车起动电机故障的实时诊断

本文主要论述阶比谱分析方法及其在汽车起动电机故障实时诊断中的应用。首先阐述了阶比谱分析的原理以及阶比采样中混迭与泄漏的产生及其抑制方法,然后讨论了如何在起动电机运行过程短、升速快的情况下获取感兴趣的噪声信号,进而采用阶比谱分析方法从信号中提取故障特征信息,最后利用阀值判别法起动电机的故障进行实时诊断。     

Force chains based mesoscale simulation on the dynamic response of Al-PTFE granular composites

Force chains based mesoscale simulation is conducted to investigate the response behavior of aluminum-polytetrafluoroethylene (Al-PTFE) granular composites under a low-velocity impact. A two-dimensional model followed the randomly normal distribution of real Al particles size is developed. The dynamic compressive process of Al-PTFE composites with varied Al mass fraction is simulated and validated against the experiments. The results indicate that, force chains behavior governed by the number and the size of agglomerated Al particles, significantly affects the impact response of the material. The failure mode of the material evolves from shear failure of matrix to debonding failure of particles with increasing density. A high crack area of the material is critical mechanism to arouse the initiation re-action. The damage maintained by force chains during large plastic strain builds up more local stresses concentration to enhance a possible reaction performance. In addition, simulation is performed with identical mass fraction but various Al size distribution to explore the effects of size centralization and dispersion on the mechanical properties of materials. It is found that smaller sized Al particle of com-posites are more preferred than its bulky material in ultimate strength. Increasing dispersed degree is facilitated to create stable force chains in samples with comparable particle number. The simulation studies provide further insights into the plastic deformation, failure mechanism, and possible energy release capacity for Al-PTFE composites, which is helpful for further design and application of reactive materials.