变频技术在舞台吊杆定位控制中的应用

以舞台调速吊杆高精度定位运行为目标,针对吊杆运行过程中的运动惯性和机械延时等影响定位精度的问题,该文设计了应用PLC、变频器、增量式编码器等组成异步电机传动的速度和位置双闭环控制系统,提出采用变频调速的二分法算法实现无极变速运动及其准确定位控制.工程实践表明,该方法凭借双闭环系统在获得理想调速性能的同时,又大幅度地提高了位置控制的定位精度.     

单片机中基于查表法的多变量函数求解方法设计

针对多变量非线性复杂函数关系式在单片机中难以实现的问题,提出了一种快速有效的查表求解算法。首先建立顺序存储数据块,接下来查找输入变量在已存变量存储块中的自然序号,最后利用查得的变量自然数序号及事先确定的算法查找这些变量所对应的函数值的存储地址,进而得到计算结果。实现了非线性复杂关系式的快速精确求解,可推广于各种运算能力有限的单片机,提高了单片机的整体使用效率。     

旅游资源两分法分类依据探讨

旅游资源两分法分类依据众说不一,为初学者带来了困惑。作者通过对现有旅游资源分类理论、实践成果的观察和分析,试图明确旅游资源两分法的分类依据,并对其进行了更深层次的辨析。     

Finding Starting Points for Tracing Surface Intersections

1 Introduction Finding out proper starting points for all the intersection curves between two surfaces is a key process in numerical tracing methods for surface-surface intersection (SSI) problems. A number of methods [1] are introduced to calculate the starting points. Cugini et al. [2] introduced the concept of shrinking bounding boxes to calculate starting points. This method is simple and in some cases effective, but it may miss some intersection components. Muellenheim [3] presented an…     

商务英语教学中英语知识与商务知识的关系

分析了商务英语教学中英语知识与商务知识的关系，对“二分法”认为英语知识高于商务知识的观点进行了商榷，并根据商务英语的基本目的和中国在校大学生普遍缺乏工作经验的实际情况，提出了在实际教学中应坚持“两手抓，两手都要硬”的教学方法。     

广义设计—建造二分讨论——以三位拉美建筑师的实践为例

随着现代分工和学科细化,建筑师丧失了其传统职业角色,与此同时,设计、建造二分作为问题浮现出来。现 有讨论多关注于狭义二分问题,围绕建筑师和工程师之间的专业分工展开,忽略了现代建造活动中还存在更为根 本的脑力劳动和体力劳动的分工,以及体力劳动者间更为细化的分工,也就是广义二分问题。相较于狭义二分问题, 广义二分问题涉及建筑学边界之外其他学科,但建筑学的根基在于建造,即使有些问题目前属于模糊地带,也应尽 力梳理清晰,在其中寻找建筑学的机遇。因此,本文希望针对广义的二分问题展开讨论：通过分析三位不同时期拉 美建筑师的思想和实践,探讨广义二分问题的可能解决路径。     

Between the Local and the Global: History of Science in the European Periphery Meets Post‐Colonial Studies

The aim of this paper is to discuss two historiographical issues pertaining to the history of science in the European periphery. The first issue concerns the wide use of the centre‐periphery dichotomy in historical accounts discussing the diffusion and institutionalization of science across the world. The second issue concerns the use of appropriation (instead of transfer, or adaptation) as a means to overcome the diffusionist model in history of science. Recent work at the intersection of history of science with post‐colonial studies will provide the framework for reassessing these matters. As it will be shown, theoretical discussions about the history of science in post‐colonial context can help historians overcome the centre‐periphery dichotomy and turn European periphery into a privileged standpoint for showing the actual diversity of ‘European science.’ At the same time, the experience of post‐colonial studies can also help sharpen the historiographical tool of appropriation. The assumption that will be made is that by focusing on appropriation rather than on discovery and innovation (the favourite categories of much of mainstream historiography), or on transfer and adaptation (the favourite categories of the diffusionist model), historians of science can not only set aside the artificial distinctions of the diffusionist model, but also bring forward the re‐inventions, the conceptual shifts and the cultural adjustments, which are responsible for the emergence of science as a global phenomenon in the periphery. Especially concerning European periphery, the use of appropriation may bring forward the particular historical circumstances under which certain knowledge patterns gained universal epistemic authority as constitutive elements of an imagined European intellectual identity.     

基于K-way谱聚类的背景离群点检测

为提高现有背景离群点检测算法背景子图划分的准确性,提出一种基于K-way谱聚类的背景离群点检测算法。构造图模型,对其进行K-way划分,使得到的背景子图具有解释性意义,从划分后的背景子图中获得离群点。实验结果表明,该算法的H指标提高50%,VI指标降低70%,其精确度有较大提高,且没有对图的结构进行改变,不会丢失重要信息。     

大位移井侧位抛物线剖面设计的数值计算

侧位抛物线剖面是大位移井轨道设计中常用的剖面类型。对侧位抛物线剖面设计求解过程中的求侧位抛物线初始点井斜角的数值方法和从段长求井斜角的数值方法进行了分析,指出其关键是求解侧位抛物线初始点井斜角所满足的一个三角函数方程。用倍角公式可将该三角函数方程转化成一个四次代数方程,然后用求根公式直接求出解析解。用解析解可简化侧位抛物线剖面设计过程,减少计算工作量,提高计算速度。侧位抛物线井段参数计算中需要通过段长公式来反求井斜角,给出了反求井斜角的二分法。本文的算法可应用于大位移井轨道设计的软件开发。     

How to Psychoanalyze a Robot: Unconscious Cognition and the Evolution of Intentionality1

According to a common philosophical distinction, the `original' intentionality, or `aboutness' possessed by our thoughts, beliefs and desires, is categorically different from the `derived' intentionality manifested in some of our artifacts –- our words, books and pictures, for example. Those making the distinction claim that the intentionality of our artifacts is `parasitic' on the `genuine' intentionality to be found in members of the former class of things. In Kinds of Minds: Toward an Understanding of Consciousness, Daniel Dennett criticizes that claim and the distinction it rests on, and seeks to show that ``metaphysically original intentionality' is illusory by working out the implications he sees in the practical possibility of a certain type of robot, i.e., one that generates `utterances' which are `inscrutable to the robot's designers' so that we, and they, must consult the robot to discover the meaning of its utterances. I argue that the implications Dennett finds are erroneous, regardless of whether such a robot is possible, and therefore that the real existence of metaphysically original intentionality has not been undermined by the possibility of the robot Dennett describes.