Assembling approximately optimal binary search trees efficiently using arithmetics

We introduce a new algorithm for computing an approximately optimal binary search tree with known access probabilities or weights on items. The algorithm is simple to implement and it has two contributions. First, a randomized variant of the algorithm produces a binary search tree with expected performance that improves the previous theoretical guarantees (the performance is dependent on the value of the input random variable). More precisely, if p is the probability of accessing an item, then under expectation the item is found after searching lg1/p+0.087+lg₂(1+pmax) nodes, where pmax is the maximal probability among items. The previous best bound was lg1/p+1, albeit deterministic. For the optimal tree our upper bound implies a non-constructive performance bound of H+0.087+lg₂(1+pmax), where H is the entropy on the item distribution and the previous bound was H+1. The second contribution of the algorithm is a low cost in i/o models of cost such as the cache-oblivious model, while attaining simultaneously the above bound for the produced tree.     

一种基于单片机的GPRS的无线数据传送系统

本文针对无线数据通信发展的需求,介绍了一套基于GPRS技术的无线数据传送系统。由单片机控制的远端数据终端将传感器采集的数据通过串行接口驱动无线Modem,经GPRS网络将数据发送到Internet上的远程监控中心,并实现数据的存储、分析处理和显示。文章从硬件和软件两方面描述了系统的设计及实现方法。     

Topology on the set of R 0 semantics for R 0 algebras

This paper introduces the concepts of R ₀ valuation, R ₀ semantic, countable R ₀ category , R ₀ fuzzy topological category , etc. It is established in a natural way that the fuzzy topology δ and its cut topology on the set Ω _M consisting of all R ₀ valuations of an R ₀ algebra M, and some properties of fuzzy topology δ and its cut topology are investigated carefully. Moreover, the representation theorem for R ₀ algebras by means of fuzzy topology is given, that is to say the category is equivalent to the category . By studying the relation between valuations and filters, the Loomis–Sikorski theorem for R ₀ algebras is obtained. As an application, K-compactness of the R ₀ logic is discussed.     

附网存储技术及Jini技术的探讨

系统介绍了附网存储与Jini技术两种新的存储方案,附网存 储具有存储设备与网络直接相连,客户机与存储器间直接传送数据的性能;Jini实现了网络 设备自发组网(即插即用),让所有盟员都共享服务。最后分析了这两种方案的市场前景。     

杯[4]芳烃醚类衍生物的合成(Ⅱ)

以对叔丁基苯酚和甲醛为起始原料，通过选用不同的催化剂，合成了一系列新的杯[4]芳烃的四醚化衍生物，并对其结构用IR、^1HNMR、^13CNMR、MR进行了表征。     

浪漫与理性交融的岭南书院——华南师范大学南海学院的规划与建筑创作

在华南师范大学南海学院的规划与建筑设计中,我们抓住大学校园空间环境的本质和地域特色,将自由浪漫的自然环境和整体理性的教育理念相结合,体现人与自然和谐共处、融于山水的特色,营造一个适应现代教育要求和充满岭南书院气息的大学校园.     

Fl?chenwidmung "Bauland-Dorfgebiet"; Immissionsschutz; Geruchsbel?stigung; (keine) subjektiv-?ffentlichen Nachbarrechte

Bei der Errichtung landwirtschaftlicher Betriebsgeb?ude kommt Nachbarn kein Immissionsschutz bezüglich Geruchsbel?stigung zu. Da das "Bauland-Dorfgebiet" vornehmlich zur Errichtung von landwirtschaftlichen Betrieben bestimmt ist, muss zwangsl?ufig ein gewisses Ma? an Geruchsbel?stigung als zul?ssig angesehen werden.     

500MPa级钢筋混凝土简支梁变形的试验分析

通过对5根500MPa级钢筋混凝土简支梁及HRB335,HRB400级钢筋混凝土简支梁各1根的对比试验,观察了试件的变形特征及破坏形态.对试验结果进行的研究分析表明,500MPa级钢筋混凝土简支梁的变形特征与普通的HRB335,HRB400级钢筋混凝土简支梁基本相同,在正常使用状态下实测的挠度大于计算挠度,建议现行设计规范应考虑这类钢筋的受力特性,并在应用条件上作出规定.     

A new single step process for synthesis and growth of ZnGeP2 crystal

A new one-step process for synthesis and growth of zinc-germanium-phosphide, ZnGeP₂ (ZGP), is reported for the first time herein using a three-zone resistance furnace by the horizontal gradient freeze technique. A safe and proper temperature scheme has been obtained for both synthesis and growth of ZGP crystals via the melt growth route from Zn, Ge and P powder. The prepared material has been investigated using powder X-ray diffraction which shows the correct ZGP tetragonal phase. EPMA results are also obtained to estimate the compositional homogeneity of the grown crystal.