广州市若干历史文化保护区保护规划

本文回顾了广州市内几个历史文化保护区规划在编制和实施。探讨历史文化保护区规划的新任务,从规划管理的角度,提出了切实可行的建议。     

Uncovering secrets behind low-resistance planing craft hull forms through optimization

There has always been significant interest within the naval architectural research community to identify ship hull forms with low resistance. While numerous design optimization frameworks have been proposed over the years to support the activity, very little attention has been paid towards the process of gaining an understanding of ‘what makes a good ship design superior?’. Furthermore, there have been limited attempts to identify computationally cheap indicators that can be used to distinguish between good and poor designs. A recent technique named discovery of innovative design principles, which is aimed at understanding the relationship between the design variables, is incorporated in this work. In this article, optimal high-speed planing craft hull forms with minimum calm-water resistance are identified through the use of three state-of-the-art optimization algorithms. Collections of such designs are then used to uncover insights into the underlying relationships between the variables. The importance of such relationships is further analysed to identify computationally cheap performance indicators that can be used in lieu of detailed calm-water resistance calculations. Such indicators are useful at the concept and preliminary design stages, where one needs to sieve efficiently through a number of candidate designs to identify the better ones for further analysis.     

Identification of acceleration deceleration profile of feed drive systems in CNC machines

In process planning, trajectory planning has generally disregarded the limitations of the feed drive systems in terms of acceleration, jerk, and motion blending. It results in poor prediction of the feed rate mainly in the transient phases and affects, consequently, the machining integrity and safety. Therefore, identifying and integrating the feed drive system limitations with the trajectory planning of the tool path are crucial in order to achieve the desired feed rate at the appropriate tool position. In this paper, a methodology based on time series modeling is proposed to identify the acceleration/deceleration (Acc/Dec) profile of a feed drive system. This profile provides the relationship between the actual feed rate, assumed proportional to the tachometer signal, and the commanded feed rate specified in the G-Code file. A particular shape of the input has been addressed to allow the application of the time series modeling. The different characteristics of this input are carefully considered to avoid both nonlinear response due to saturation and excitation of the high frequency components of the feed drive. The resulting model is transformed into a Finite Impulse Response (FIR) filter and applied as an (Acc/Dec) processor to determine the actual feed rate from the commanded feed rate. The good agreement between the model output and the experimental results demonstrates the effectiveness of the proposed identification method. It is demonstrated that integrating these limitations with the trajectory planing results in a feasible trajectory.     

改革开放后上海城市总体规划回顾与展望

改革开放后,上海经历了二轮经国务院批准的城市总体规划。这两轮规划始终坚持1946年《大上海都市计划》所提出的"疏解城市人口与功能、形成多心多核的城市功能结构和环状与楔形绿地结合的城市空间形态"。同时不断完善,追求更高层次的社会、经济与环境的协调和可持续发展,贯彻公共政策的规划原则和价值观,并于2005年起谋划《上海市城市总体规划中期实施评估》。在后一轮总规编制时对总体规划编制方法的完善进行了探索与实践,对"战略规划"的一些核心思想从不同角度进行了研究与思考。     

电缆包装盘的拱形刀具设计

介绍了只需将四面刨床的刨刀形状加以改进,就能将四面刨床改造成为专用拱形刨床的方法,以使设备可以满足电缆包装盘生产的要求.     

拖拉机轮毂内孔键槽刨削让刀的分析及刨刀的设计

分析了手扶拖拉机车轮毂内孔键槽刨削加工时产生“让刀”现象的原因 ,并对内孔键槽的刨削极限深度、刀杆强度等进行计算与校核 ,提出了轮毂内孔键槽刨削的最佳切削参数。     

MBJ18/55型刨煤机的设计

MBJ18/55型刨煤机是一种外牵引的浅截式薄煤层采煤机,采用刨削的方式落煤,并通过煤刨的犁面将煤装入工作面输送机,实现刮板输送机的连续运输,刨煤部分的传动装置独立驱动刨体往复运动,实现刨煤工作,刨煤机与工作面输送机一起组成刨煤机组。     

机器人抓取运动目标的轨迹规划方法

本文讨论了机器人在抓取运动目标前的接近轨迹规划问题，给出了一种新的在平面上抓取目标的方案。这种方案适用于机器人接近作直线运动或轨迹已知的平面曲线运动的目标的轨迹规划。本文还研究了当目标沿直线以不同速度运动时机器人手爪要抓取它而必须达到的最小末端速度，最后给出了一些仿真结果。     

桐子林水电站二期截流规划设计

桐子林水电站为雅砻江流域最后一个电站,截流流量较大,且截流流量受上游已建电站发电的影响,流量变幅大,因此,拟通过上游不同发电流量分析二期截流水力学指标,分析二期截流难易程度,推荐截流流量。     

Motion stability and control of supercavitating vehicle with variable cavitation number

Cavitation number and speed are capable of variation during the motion of supercavitating vehicle underwater,for example,under the condition of accelerated motion stage and external disturbance.The dynamic model and control challenge associated with the longitudinal motion of supercavitating vehicle with variable cavitation number and speed have been explored.Based on the principle of cavity expansion independence the properties of cavity and the influence on planning force of body were researched.Calculation formula of efficiency of the fin was presented.Nonlinear dynamics model of variable cavitation number and speed supercavitating vehicle was established.Stabilities of the open-loop systems of different situations were analyzed.The simulations results of open-loop systems show that it is necessary to design a control method to control a supercavitating vehicle.A gain schedule controller with guaranteed H∞ performance was designed to stabilize the dive-plane dynamics of supercavitating vehicle under changing conditions.