爆炸排淤填石法中淤泥的本构模型

以爆炸排淤填石法为背景 ,对不同应变率阶段淤泥的本构模型进行了分析 ,利用ANSYS/LS-DYNA动态有限元分析程序对所选择的模型进行验证和确认。计算和分析结果表明 :在形成爆炸空腔的高应变率阶段 ,淤泥表现为理想不可压缩流体的性质 ;在小药量小抵抗线条件下 ,甚至在淤泥自重作用下的较低应变率变形阶段 ,其黏性效应也可以忽略不计。     

多传感器检测中的数据溶合技术

多传感器检测是使用多种(或多个)传感器对同一被测对象进行广泛的测量。应用多传感器检测技术和多传感器数据溶合技术对车削加工中的零件外圆尺寸检测进行了实验研究,结果表明,多传感器检测技术能够满足现代检测技术对信息的精确要求,使得检测监控系统更加准确、可靠。     

柔性不饱和聚酯树脂的研究进展

综述了主链结构、接枝引入柔性链段、交联剂对柔性不饱和聚酯树脂（UPR）性能的影响和进一步提高UPR柔韧性的一些途径，如弹性体增韧、无机物增韧、互穿网络（IPN）增韧，并对柔性UPR的发展趋势进行了预测。     

Association-Based Active Access Control models with balanced scalability and flexibility

In existing Active Access Control (AAC) models, the scalability and flexibility of security policy specification should be well balanced, especially: (1) authorizations to plenty of tasks should be simplified; (2) team workflows should be enabled; (3) fine-grained constraints should be enforced. To address this issue, a family of Association-Based Active Access Control (ABAAC) models is proposed. In the minimal model ABAAC₀, users are assigned to roles while permissions are assigned to task-role associations. In a workflow case, to execute such an association some users assigned to its component role will be allocated. The association's assigned permissions can be performed by them during the task is running in the case. In ABAAC₁, a generalized association is employed to extract common authorizations from multiple associations. In ABAAC₂, a fine-grained separation of duty (SoD) is enforced among associations. In the maximal model ABAAC₃, all these features are integrated, and similar constraints can be specified more concisely. Using a software workflow, case validation is performed. Comparison with a representative association based AAC model and the most scalable AAC model so far indicates that: (1) enough scalability is achieved; (2) without decomposition of a task, different permissions can be authorized to multiple roles in it; (3) separation of more fine-grained duties than roles and tasks can be enforced.     

21世纪塑性加工面临的挑战──对几个问题的看法

在２１世纪即将到来之际，塑性加工面临严峻的挑战。企业的主要领导者和主要技术人员应从指导思想与哲理上、技术上、运营方式上以及人材培养等方面做好充分准备。作者在本文中对下述几方面的问题进行了探讨，提出作者的粗浅看法，供同行们讨论。这些方面包括市场导向、柔性化、自动化策略、准时制与精良生产、并行工程、集成化与智能化、人的因素、教育与培训等。     

基于元数据的柔性信息系统建模与实现

介绍数据柔性、数据柔性分析等相关概念。通过引入元数据,提出并建立数据柔性的层次模型和柔性数据的访问模型,以解决用户数据结构如何适应转化的关键问题。在数据柔性分析与建模中,提出以元数据为核心的软件设计方法,并将该方法和所建立的数据柔性理论应用于柔性软件信息系统的开发和软件工程实践中。     

Unlocking the value of flexibility of behind-the-meter prosumers: An overview of mechanisms to esteemed trends

Behind-the-meter (BTM) resources is being recognized as a viable solution to offer grid services including flexibility procurement which is required for volatile renewable power systems. This paper brings an overview of current and esteemed frameworks and respective challenges revolving around BTM flexibility notion and mechanisms. To begin with, we review grid architectures, e.g., microgrids and virtual power plants, capable of accommodating BTM flexibility and desirable flexibility market designs, including peer-to-peer trading. The role of machine learning initiatives, including reinforcement learning and probabilistic forecasting, in designing reliable energy management systems is extensively deliberated. Last but not least, supplementary discussions in making this concept a reality, which can be regarded as future research, are given.     

Modular architecture of the microfactories for automatic micro-assembly

The construction of a new generation of MEMS which includes micro-assembly steps in the current microfabrication process is a big challenge. It is necessary to develop new production means named micromanufacturing systems in order to perform these new assembly steps. The classical approach called “top-down” which consists in a functional analysis and a definition of the tasks sequences is insufficient for micromanufacturing systems. Indeed, the technical and physical constraints of the microworld (e.g. the adhesion phenomenon) must be taken into account in order to design reliable micromanufacturing systems. A new method of designing micromanufacturing systems is presented in this paper. Our approach combines the general “top-down” approach with a “bottom-up” approach which takes into account technical constraints. The method enables to build a modular architecture for micromanufacturing systems. In order to obtain this modular architecture, we have devised an original identification technique of modules and an association technique of modules. This work has been used to design the controller of an experimental robotic micro-assembly station.     

Multi-objective FMS process planning with various flexibilities using a symbiotic evolutionary algorithm

This paper presents an evolutionary algorithm, called the multi-objective symbiotic evolutionary algorithm (MOSEA), to solve a multi-objective FMS process planning (MFPP) problem with various flexibilities. The MFPP problem simultaneously considers four types of flexibilities related to machine, tool, sequence, and process and takes into account three objectives: balancing the machine workload, minimizing part movements, and minimizing tool changes. The MOSEA is modeled as a two-leveled structure to find a set of well-distributed solutions close to the true Pareto optimal solutions. To promote the search capability of such solutions, two main processes imitating symbiotic evolution and endosymbiotic evolution are introduced, together with an elitist strategy and a fitness sharing scheme. Evolutionary components suitable for the MFPP problem are provided. With a variety of test-bed problems, the performance of the proposed MOSEA is compared with those of existing multi-objective evolutionary algorithms. The experimental results show that the MOSEA is promising in solution convergence and diversity.     

Does prolonged sitting with limited legroom affect the flexibility of a healthy subject and their perception of discomfort?

This study examined for differences in subjective ratings of discomfort and comfort (Numerical Rating Scale) and objective measures of hamstring (Sit-Reach test), lumbar (Schöber’s test) and neck (Cervical Range of Motion) flexibility in healthy young subjects (n = 24) following 4 h of sitting on stacking chairs with or without limited legroom.When comparing the limited and unlimited legroom groups for differences in subjective and objective measures over 4 h, no significant findings were seen at the 5% level of confidence. However, differences in buttock, neck, shoulder and average discomfort were significantly negatively correlated to differences between post-warm up Sit-Reach scores (Correlation Co-efficients: −.763, −.434, −.408, and −.445; p values of .004, .034, .048, and .029, respectively). The difference in buttock discomfort was significantly negatively correlated to the difference between pre-warm up Sit-Reach scores (Correlation Coefficient: −.750; p = 0.005), post-sitting/pre-warm up and pre-sitting/post-warm up Sit-Reach scores (Correlation Coefficient: −.756; p = 0.004), and Schöber’s tests (Correlation Coefficient: −.578; p = 0.049).Although the above results suggest a relationship between a loss in flexibility and an increase in discomfort, the mechanism influencing this relationship is not clear from this study. What does appear clear is that the limiting of legroom to the parameters used in this study does not seem to exacerbate change in flexibility and discomfort which are a consequence of prolonged sitting.

Relevance to industry

Many forms of public transport provide limited legroom for their passengers, which may have an adverse affect on the user’s flexibility or experience of discomfort. Determining which objectively measurable parameters are associated with the subjective level of discomfort during sitting should allow for a greater appreciation of the changes that underpin such subjective perceptions.