干旱区荒漠植被动力学及恢复对策调控指标分析

干旱区贫瘠土壤和植被单一是立地质量的重要指标,在水平结构上表现为一种有、无植被及不同种群组成的镶嵌分布,镶嵌分布具有的不均匀性在尺度变换下具有不变性特征;立地质量决定了抵抗破坏力度和恢复力度均弱,因而原生植被破坏时残存的幼苗或幼树经长期恢复形成了顶级单优结构。这就为应用生态学最著名的种群模型来研究其动力学行为奠定了基础。对动力学模型中的控制参数利用多种调控因子的组合分析,定量化地进行了受控变化研究,通过深入调试各种调控因子的数值范围、最佳指标的数值域和危险指标的数值域后,可提供便于操作的具体数据范围。

Optimal Batching Structures of Single Machine Scheduling

A batch is a subset of jobs which must be processed jointly in either serial or parallel form. For the single machine, batching, total completion time scheduling problems, the algorithmic aspects have been extensively studied in the literature. This paper presents the optimal hatching structures of the problems on the batching ways： all jobs in exactly N（arbitrary fix batch number and 1 〈 N 〈 n） batches.

Multi-criteria assessment of offshore wind turbine support structures based on dynamic property optimization

Increasing size of wind turbine and deep water deployment have raised the issue of appropriate selection of the most suitable support structure to make offshore wind energy cost competitive.The paper presents an optimization methodology for decision making process of bottom mounted supports of offshore wind turbines （OWTs） through reasonable engineering attributes derivation.Mathematic models of support structures are reduced by the generalized single-degree-of-freedom theory with relatively fewer structural parameters.Soft-stiff design optimization based on dynamic properties of OWTs is performed for monopile and lattice supports with different wind turbines,water depth and hub height.Attributes of support structures,wind turbines and environment conditions are applied in the multi-criteria decision making method——TOPSIS for benchmarking of those options.The results illustrate the effectiveness of the proposed optimazation methodology combined with economical and environmental attributes together.

Research on Network-on-chip Dynamic and Adaptive Algorithm and Choice Strategy

With further increase of the number of on-chip device, the bus structure has not met the requirements. In order to make better communication between each part, the chip designers need to explore a new structure to solve the interconnection of on-chip device. The paper proposes a network-on-chip dynamic and adaptive algorithm which selects NoC platform with 2-dimension mesh as the carrier, incorporates communication energy consumption and delay into unified cost function and uses ant colony optimization to realize NOC map facing energy consumption and delay. The experiment indicates that compared with random map, single objective optimization can separately saves （30% - 47 %） and （ 20% - 39%） in communication energy consumption and execution time compared with random map, and joint objective optimization can further excavate the potential of time dimension in mapping scheme dominated by the energy.

Node shift method for stiffness-based optimization of single-layer reticulated shells

This paper presents a node shift method to find the optimal distribution of nodes in single-layer reticulated shells. The optimization process searches for the minimum strain energy configuration and this leads to reduced sensitivity in initial imper- fections. Strain energy sensitivity numbers are derived for free shift and restricted shift where nodes can move freely in the 3D space or have to move within a predefmed surface respectively. Numerical examples demonstrate the efficiency of the proposed approach. It was found that optimized structures achieve higher ultimate load and are less sensitive to imperfections than the initial structure. The configuration of the final structure is closely related to factors like the initial structural configuration, spatial conditions, etc. Based on different initial conditions, architects can be provided with diverse reasonable structures. Furthermore, by amending the defined shapes and nodal distributions, it is possible to improve the mechanical behavior of the structures.

A novel method of dynamic characteristics analysis of machine tool based on unit structure

A novel approach,which can be used for dynamic characteristics analysis of machine tools based on unit structure(US),is reported in this paper.The concepts of unit structures for design of machine tools are defined.In order to satisfy the dynamic characteristics requirement of high natural frequency and light-weight of US,a design method of multi-disciplinary optimization of NSGA-II about unit structures driven by natural frequency and mass is developed.Through analyzing the unit structures,key factors affecting the natural frequency and mass are extracted,and the mathematical models of natural frequency and mass about unit structures are also established by using central composite design and response surface model.The goal of high natural frequency and light-weight is reached by using the multi-objective genetic algorithms.The Pareto optimal set is also obtained.The dynamic behavior of US is investigated by the experimental modal analysis.To show the efficiency of the proposed novel method,the example of YKW51250 gear shaping machine bed is used.Through optimization of NSGA-II about US of YKW51250 machine bed,the natural frequency of YKW51250 gear shaping machine bed is increased by 30.4%and its mass decreased by 5.2%comparing with the original design.By studying the dynamic characteristics of the simplified machine tools bed,useful laws are obtained,and these laws can be used in primary design of NC machine tools structures.The optimal method based on US can be also applied to the dynamic optimal design of machine tools and other similar equipments.