弹性半无限空间中矩形孔收缩的复变函数解答

随着城市建设的发展,矩形隧道的应用越来越多,但针对矩形隧道的理论研究却鲜有见闻。针对矩形隧道,建立了半无限空间矩形隧道的弹性理论计算模型,采用最小二乘迭代方法确定共形映射函数的各项系数,并将计算区域映射为复平面上的一个同心圆环;运用Muskhelishvili复变函数方法,将计算区域内的应力函数展开成为Laurant级数的形式,给定了地表零应力边界和矩形孔口径向位移边界,求得了半无限空间矩形隧道在给定位移条件下的应力场和位移场。分析了不同高宽比、不同泊松比、不同埋深对位移场和应力场的影响,总结了矩形隧道位移场和应力场的一般规律。结果表明：高宽比偏小、泊松比偏大、埋深偏小都会使得沉降槽不再是类高斯曲线的形状,这些参数的变化也会在不同程度上影响应力场和位移场的大小和分布。     

基于等流量法缩减空间策略的水电站调度方法

采用合理的调度方法可有效提高水电站发电效益。模拟方法容易获取可行解,但不能提供最优解;优化方法能够求得最优解,但往往因搜索空间过大而求解不理想。本文考虑两者特点,提出基于等流量法缩减空间策略的水电站调度方法,即利用等流量法模拟调度过程,缩减搜索空间,在缩减空间内利用优化方法求解模型。实例研究表明：该方法适合群智能算法求解水电站调度模型;在相同群智能算法和水电站调度模型下,缩减搜索空间后,多年平均发电量、保证出力提升显著,多年平均弃水量明显减少。此外,群智能算法在缩减空间内的收敛速度更快,标准差更小。因此,该方法能够有效提高群智能算法求解的优化程度、收敛速度和稳定性,可为水电站调度提供重要参考。     

直流预压对针板电极下XLPE中空间电荷及电树枝的影响

空间电荷是影响高压直流电缆绝缘电树枝特性的主要原因之一。基于双极性载流子输运模型,对±20 kV、±22.5 kV和±25 kV直流预压下3 600 s内二维针板电极模型空间电荷分布进行仿真分析,并对比分析空间电荷分布与直流接地电树枝引发特性。结果表明：空间电荷浓度及注入深度随预压幅值及时间的增加而增大;直流接地电树枝引发长度随预压时间及幅值的增加而增加。空间电荷注入深度与电树枝引发长度两者之间高度相似。接地电树枝引发特性存在差异的主要原因是针尖附近空间电荷的分布特性。     

空间高能质子对飞行器材料的损伤分析

针对高能粒子在空间环境中的辐射,本文简要介绍了空间高能质子在空间环境中的分布情况及在物质中的传输问题,评述了国外有关高能质子的非电离能损失及线性能量转移研究,并在此基础上重点分析和研究了高能质子对航空、航天材料的辐射损伤.从空间高能质子对材料的辐射损伤的角度,分析讨论了材料厚度与屏蔽效果的关系并提出了一些相关性的结论和展望;能量为10MeV～80MeV的质子最可能发生辐射损伤效应,质子拟合公式适合于入射质子能量较小的情况.     

Analysis of the physical properties of an in-vessel composting matrix

Efficient compost production requires a thorough understanding of the process dynamics in terms of the feedstock materials used and the interactions of the physical properties involved. The main properties affecting the composting process are temperature, moisture content, bulk density, porosity and oxygen availability. In this study, the correlations between a selected set of physical properties of a batch-composting matrix were determined. The key physical changes in the composting materials for a blend of woodchips, chicken manure and mixed green vegetables have been monitored during a 36-day composting period in a 200-L rotary drum. The daily measurements conducted on the solid samples included temperature, pH, volatile solids, bulk density, moisture content, free airspace and substrates particle density while the carbon dioxide release was monitored weekly using jar respiration tests. The results from the compost process monitoring were a maximum temperature rise to 66.3 °C over the first 3 days, a marked decrease in free airspace from 76.3% to 40.0% at the end of the process, a variation in average composting material particle density from 1097 kg/m³ to 2325 kg/m³, and an increase in wet bulk density from 255 kg/m³ to 628 kg/m³. Correlations developed among free airspace, wet bulk density, dry bulk density and wet moisture content were in agreement with previously determined equations from literature. Free airspace varied linearly with both dry and wet bulk densities (R² value of 0.89 and 0.95, respectively) while the free airspace-wet moisture content profile followed a fourth degree polynomial trend with a correlation coefficient of 0.63.     

低空复杂环境下基于采样空间约减的无人机在线航迹规划算法

针对低空复杂环境下障碍物密集且类型多样、带有多通道并存在不确定信息的无人机在线航迹规划问题,为了减少碰撞检测次数,提高航迹搜索速度,降低航迹代价,提出一种基于采样空间约减的无人机在线航迹规划算法. 算法通过引入代价模型,提出约减域逐步构造方法,引导规划树快速有效扩展,改善了基于动态域的快速拓展随机树（Dynamic domain rapidly-exploring random tree,DDRRT） 算法中存在的采样空间过度约减问题. 算法通过密度划分索引的方法逐步构建多棵Kd 树（K-dimensional tree）并采用多近邻节点搜索方法,加快了近邻树节点搜索速度. 仿真实验结果表明,与DDRRT方法相比,该方法在保证对采样空间约减合理性的同时,提高了航迹规划效率和通道内的寻路能力.     

Computational Problem Solving in Spatial Substrates -- A Cognitive Systems Engineering Approach

The ability to perform spatial tasks is crucial for everyday life and of great importance to cognitive agents such as humans, animals, and autonomous robots. A common artificial intelligence approach to accomplish spatial tasks is to represent spatial configurations and tasks in form of detailed knowledge about various aspects of space and time. Suitable algorithms then use the representations to compute solutions to spatial problems. In comparison, natural embodied and situated agents often solve spatial tasks without detailed knowledge about geometric, topological, or mechanical laws; they directly relate actions to effects that are due to spatio-temporal affordances in their bodies and environments. Accordingly, we propose a paradigm that makes the spatio-temporal substrate an integral part of the engine that drives spatial problem solving. We argue that spatial and temporal structures in body and environment can substantially support (and even replace) reasoning effort in computational processes: physical manipulation and perception in spatial environments substitute formal computation. While the approach is well known – for example, we employ diagrams as spatial substrate for geometric problem solving and maps for wayfinding – the underlying principle has not been systematically investigated or formally analyzed as a paradigm of cognitive processing. Topology, distance, and orientation constraints are all integrated and interdependent in truly 2- or 3-dimensional space. Exploiting this fact may not only help overcome the need for acquiring detailed knowledge about the interrelationships between different aspects of space; it also can point to a way of avoiding exploding computational complexity that occurs when we deal with these aspects of space in complex real-world scenarios. Our approach employs affordance-based object-level problem solving to complement knowledge-level formal approaches. We will assess strengths and weaknesses of the new cognitive systems paradigm.     

渠首水位实时调控模型——以船行灌区一支渠为例

很多大中型灌区在输配水过程中存在水位衔接不当的问题,加之田面高程存在起伏,使得灌溉时往往存在部分田面不能上水或受淹等问题。本文提出了空间灌溉率的概念,并利用GIS的三维分析功能研究了其与渠道渠首水位之间的关系。分析表明,空间灌溉率与渠首水位之间的关系符合Logistic曲线;针对船行灌区一支渠,得到该Logistic曲线的参数,并确定了一支渠渠首和干渠渠首不同空间灌溉率所需的水位,为灌区水位实时调控提供基础数据。     

State space model predictive fault-tolerant control for batch processes with partial actuator failure

This paper presents a state space model predictive fault-tolerant control scheme for batch processes with unknown disturbances and partial actuator faults. To develop the model predictive fault-tolerant control, the batch process is first treated into a non-minimal representation using state space transformation. The relevant concepts of the corresponding model predictive fault-tolerant control is thus introduced through state space formulation, where improved closed-loop control performance is achieved even with unknown disturbances and actuator faults, because, unlike traditional model predictive fault-tolerant control, the proposed control method can directly regulate the process output/input changes in the design. For performance comparison, a traditional model predictive fault-tolerant control is also designed. Application to injection velocity control shows that the proposed scheme achieve the design objective well with performance improvement.