The Periodic System of Chemical Elements. An Essay Review

J. W. van Spronsen, The Periodic System of Chemical Elements. A History of the First Hundred Years , Amsterdam (Elsevier), 1969, pp. XV + 368, Dfl. 50.     

非线性挤压油膜阻尼器柔性转子系统中的周期分叉特性

利用轴心轨迹、Ｐｏｉｎｃａｒｅ映射及分叉图等方法，详细地研究了支承在非线性挤压油膜阻尼器上的柔性转子系统中的周期分叉特性。     

复杂柔性隔振系统研究概述

从研究对象,建模方法和评价指标三个方面阐述复杂柔性隔振系统,主要是浮筏隔振系统的研究概况。重点讨论隔振系统中的子结构弹性和隔振器的驻波效应;并讨论子结构方法,有限元法和功率流方法。     

An Integrated Flexible All-Nanowire Infrared Sensing System with Record Photosensitivity

Infrared (IR) photodetectors are a key optoelectronic device and have thus attracted considerable research attention in recent years. Photosensitivity is an increasingly important device performance parameter for nanoscale photodetectors and image sensors, as it determines the ultimate imaging quality and contrast. However, photosensitivities of state-of-the-art low-dimensional nanostructure-based IR detectors are considerably low, limiting their practical applications. Herein, a biomimetic IR detection amplification (IRDA) system that boosts photosensitivity by several orders of magnitude by introducting nanowire field effect transistors (FETs), resulting in a peak photosensitivity of 7.6 × 10⁴ under an illumination of 1342 nm, is presented. Consequently, high-contrast imaging of IR light is obtained on the flexible IRDA arrays. The image information can be then trained and recognized by an artificial neural network for higher image-recognition efficiency. This work provides a new perspective for developing high-performance IR imaging systems, and is expected to undoubtedly enlighten future work on artificial intelligence and biorobotic systems.     

具有自消化引擎的库存模型初探

具有自消化引擎的库存模型是与传统库存完全不同的库存模型.自消化引擎库存是指库存系统具有内循环需求引擎、库存物资具有自修复能力以及寿命递减等生命库存的特征,库存的保有量与物资的用途、使用方法、技术定义、管理模式以及外部变化或扰动等密切相关.本文提出自消化引擎这一概念来描述这类库存的模型特征,并对这类库存模型的相关特征进行了讨论和初步研究.     

面向柔性制造环境的智能集成诊断系统

介绍了一个面向柔性制造环境的智能集成诊断系统的结构与功能，并研究了相关的诊断信息集成，诊断模型和诊断推理等关键技术，最后给出了研究的结论。     

Two Periodic Review inventory Models with Backorders and Stuttering Poisson Demands

Two periodic review inventory models, (R, T) and (nQ, r, T), are analyzed for the situation where demands are characterized by either a Poisson or stuttering Poisson process. In each model, backorders are allowed and the procurement lead time is considered to be a constant. Average annual cost equations are developed for each model and solution techniques presented, so that minimum average annual costs can be determined. A numerical example is also presented. It is shown for large times between reviews that the (R, T) and (nQ, r, T) models are essentially equivalent.     

Continuous Review Perishable Inventory Systems: Models and Heuristics

We consider continuous review perishable inventory models with renewal batch demands. Assuming zero lead time, we construct an embedded Markov chain. With a probabilistic approach, we derive a closed-form long run average cost function under the (s, S) replenishment policy. Numerical analysis is then used to identify the properties of the cost function and to demonstrate the impacts of changing batch sizes and other system parameters. Based on these results, a heuristic approach to handle problems with positive lead times is proposed. The performance of the heuristics against simulation results demonstrates its effectiveness and accuracy     

An Algorithm for the Computer Control of a Flexible Manufacturing System

The problem of production management for an automated manufacturing system is described. The system consists of machines that can perform a variety of tasks on a family of parts. The machines are unreliable, and the main difficulty the control system faces is to meet production requirements while the machines fail and are repaired at random times. A multilevel hierarchical control algorithm is proposed which involves a stochastic optimal control problem at the first level. Optimal production policies are characterized, and a computational scheme is described.     

Scheduling in a Multistage Production System with Set-up and Inventory Costs

This paper considers a multistage production system with constant known demand rate across an infinite horizon. A unit of product passes through the stages sequentially, so each stage draws from the in-process inventory of the previous stage. Each stage of the process is assumed to produce at a fixed, known, finite rate greater than the demand rate, so that it must be shut down and restarted periodically. Different stages may produce at different rates. This paper describes a procedure to find the start-up and shut-down schedule of each production stage which minimizes the sum of inventory costs and set-up costs for the system. This problem is solved using dynamic programming.     

具有有效期易变质品的最优补货策略研究

易变质物品库存管理策略一直是实务界与学术界高度关注的问题,其中具有有效期易变质物品的最优补货策略是研究中的难点。本文研究了有限销售时域内具有有效期易变质物品的库存补货策略,在物品的需求率依赖于物品的库存水平,且物品有效期已知的假设下,本文建立了一个确定易变质物品最优补货策略的优化模型,并给出了具体的求解算法。文章最后给出了数值算例,并对模型中的相关参数作了敏感性分析。     

An Application of Multi-echelon Inventory System Theory to Management of Equipment Maintenance

ＡｎＡｐｐｌｉｃａｔｉｏｎｏｆＭｕｌｔｉｅｃｈｅｌｏｎＩｎｖｅｎｔｏｒｙＳｙｓｔｅｍＴｈｅｏｒｙｔｏＭａｎａｇｅｍｅｎｔｏｆＥｑｕｉｐｍｅｎｔＭａｉｎｔｅｎａｎｃｅＺｈａｏＪｉａｎｍｉｎＯｒｄｎａｎｃｅＥｎｇｉｎｅｅｒｉｎｇＣｏｌｅｇｅＳｈｉｊｉａ...     

有碰撞存在的多体振动系统的周期运动和稳定条件

有碰撞存在的多体振动系统在工程中应用甚广,但由于运动过于复杂,过去一般限于研究和利用个别特殊系统.本文考虑任意多个串联质体在多个正弦力的激励下振动,并和多个自由体碰撞(弹性或塑性碰撞)的一般情况,提出振动和稳定的统一解法.首先按工程需要选择周期运动的界点(碰撞点与脱离点),以避免解非线性方程.然后采用矩阵迭代方法求得周期运动的简便条件及其若干推论(如界点的最多个数、周期运动的存在唯一条件等).再用差分方程和矩阵迭代确定周期运动的稳定条件.文末讨论了多体系统的多种功能,如参数稳定区域大、优化程度高、自动消振和隔振等,可以充分加以利用.     

A Hybrid Inventory System with a Time Limit on Backorders

Traditionally, in ( Q , r ) inventory systems, when a shortage occurs, incoming demands are either filled by emergency orders or backordered. However, the backorder costs are usually time-dependent, hence it is costly to backorder early in the lead time. On the other hand, it is obviously expensive to fill the shortages with emergency orders alone. In this paper, we propose a hybrid inventory control system to handle shortages. A cutoff time τis incorporated with the traditional ( Q , r ) systems. Poisson demands and a constant lead time are assumed. Shortages are covered by emergency orders before τand backordered after τ. The traditional backorder and emergency order systems are special cases of the hybrid system with τ= 0 and τ= lead time, respectively. The optimal control variables Q *, r *, and τ* are determined by minimizing the expected annual cost. Numerical examples to illustrate the model are presented together with discussions on the conditions under which the hybrid system provides cost savings over the two traditional systems.     

考虑机器故障的短生命周期产品库存模型

在考虑机器故障、返修费用和担保费用以及短生命周期产品库存成本随着时间呈非线关系的情况下建立短生命周期产品经济制造批量模型,并提供了寻求上述模型唯一最优解的简便方法.举数字实例进行了说明,计算实例验证了该方法的有效性.研究分析了机器故障率、返修费用和担保费用对最优生产批量和单位时间总成本的影响,同时比较了一般产品与短生命周期产品在生产策略上的一些区别,得到了一些有价值的结论.     

具有工序顺序柔性的车间调度问题研究综述

某些加工车间在生产过程中具有多种柔性,工序顺序柔性就是其中重要的一种。通过对具有工序顺序柔性的车间调度问题的优化求解,能够极大地提高生产效率,节约生产成本。本文对具有工序顺序柔性的车间调度问题的研究现状进行整理分析,主要包括混合车间调度问题(mixed shop scheduling problem, MSP)、分组车间调度问题(group shop scheduling problem, GSP)和部分车间调度问题(partial shop scheduling problem, PSP)。最后,指出了具有工序顺序柔性的车间调度问题的发展前景及发展方向。     

具有分布时滞的广义系统的周期解问题?

周期解问题已成为广义系统领域的一个重要分支,它在许多实际问题中有着更为广泛的应用.本文主要讨论含有离散时滞和分布时滞的广义系统的周期解问题.利用特征方程和傅里叶级数理论给出了广义系统周期解存在的充分必要条件,并给出了二维广义系统周期解存在性的代数判据.利用不动点定理讨论了非线性广义时滞系统周期解的存在唯一性的若干充分条件.最后给出数值算例说明主要结果.     

柔性染料敏化太阳能电池和柔性钙钛矿太阳能电池关键电极材料研究进展

柔性太阳能电池具有轻便、可弯曲的优点,可用于可穿戴设备等器件的即时充电,具有广阔的应用前景,受到持续广泛的关注。柔性太阳能电池制备中的关键在于基材以及与之相关的电极材料的制备。本文综述了柔性染料敏化太阳能电池和柔性钙钛矿太阳能电池近几年的发展情况,着重介绍了柔性染料敏化太阳能电池光阳极、对电极以及柔性钙钛矿太阳能电池的底电极和电子传输层。结果发现高温烧结目前仍是制备高效染料敏化太阳能电池光阳极不可避免的方法,而对电极则不受这一限制并且已经有多种材料的效率超过了高温烧结的铂。柔性钙钛矿太阳能电池的研究重点是用其他材料代替底电极中柔性较差的ITO以及高温烧结的电子传输材料TiO₂,并且都取得显著成效。在此基础上,展望了柔性染料敏化太阳能电池和柔性钙钛矿太阳能电池未来的发展方向。     

柔性制造环境下基于质量控制的状态监控系统

以ＦＭＳ环境下加工单元为对象，建立了通用集成化设备与过程状态监控系统，给出了系统体系结构与硬软件组成，探讨了实际柔性生产过程中实时在线的状态监控系统实现的信息获取，状态描述，开放体系，状态辨识，异常与故障综合决策等关键技术。     

柔性板基础隔振系统的柔性多体动力学理论建模

根据舰艇机械隔振系统的特点,首先利用瑞利—里兹法推导了柔性板的动力学方程,然后结合柔性多体动力学理论,推导柔性板基础上的隔振系统的动力学模型。