Disasters in topology without the axiom of choice

We show that some well known theorems in topology may not be true without the axiom of choice. Received: 29 August 1995 / Revised version: 23 June 2000 / Published online: 3 October 2001     

An XPS Study of Perovskite Oxides RECr03

Perovskite Oxides RECr0₃ (RE=La, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb) were prepared by the means of solid state reaction.The measurments of XRD and XPS showed that the replacement by rare earth element lowers the binding energy(BE) of rare earth ions, compared with their sesquioxides. In the Perovskite Oxides, the BE of Cr2p_3/2 increases with the decrease of ionic radius of the RE ion.The reason for the changes of BE are discussed.     

智能家居系统中无线传感器网络的设计

介绍了ZigBee无线传感器网络,将ZigBee技术应用到智能家居系统中。提出了一种以ZigBee技术为基础的智能家居系统设计方案。阐述了无线传感器网络的总体构成,以CC2430无线芯片为核心,选取了合适的ZigBee模块进行了硬件电路设计。研究并分析了ZigBee技术。设计并实现了串口收发程序,传感器程序,以及节点间的无线通信程序,并根据ZigBee协议,使节点组成树状网络,最终实现系统的监测与控制。结果表明,本系统运行稳定,达到了设计目的,有着广泛的应用前景。     

基于ZigBee技术的智能家居系统

为了满足手机短信远程控制家电设备的需要,应用GR64和CC2430为核心开发了一种基于无线传感器网络的智能化短信远程控制系统。系统硬件部分主要由短信（SMS）收发模块、红外收发模块、微处理器模块、存储模块和供电模块等组成;软件部分给出了ZigBee无线通信协议的工作原理、家庭网关的设计流程。试验表明,该系统具有良好的可扩展性、低成本、低功耗、低延时、低复杂度等特点,在智能家居系统中具有广阔的应用前景。     

基于ZigBee的无线红外防盗报警系统设计

结合红外防盗报警和ZigBee技术这两大热点课题,利用TI公司的单芯片CC2430和RE200B红外传感器,完成了基于ZigBee技术无线红外防盗报警系统的硬件设计和软件开发,解决了现有无线报警系统存在的误报警,成本高等问题。经过对系统的硬件软件电路调试,验证了系统预期的功能。     

一种独立供电系统的野外远程小型气象站设计

针对野外环境和地质灾害监测具有不易采用市电供电、难以采用长距离有线传输数据、无法准确及时发现和处理故障的特点,给出了一种采用风光互补独立供电系统、GPRS远程数据传送并具有故障自诊断功能的小型气象站。系统采用CC2530作为主控MCU,便于与现场的其他监测对象通过ZigBee技术组网汇集数据;远程上位机采用LabVIEW编程。数据传输稳定、实时性好。     

Intuitionistic completeness of first-order logic

We constructively prove completeness for intuitionistic first-order logic, iFOL, showing that a formula is provable in iFOL if and only if it is uniformly valid in intuitionistic evidence semantics as defined in intuitionistic type theory extended with an intersection operator.     

The strength of extensionality II — Weak weak set theories without infinity

By obtaining several new results on Cook-style two-sorted bounded arithmetic, this paper measures the strengths of the axiom of extensionality and of other weak fundamental set-theoretic axioms in the absence of the axiom of infinity, following the author’s previous work [K. Sato, The strength of extensionality I — weak weak set theories with infinity, Annals of Pure and Applied Logic 157 (2009) 234-268] which measures them in the presence. These investigations provide a uniform framework in which three different kinds of reverse mathematics-Friedman-Simpson’s “orthodox” reverse mathematics, Cook’s bounded reverse mathematics and large cardinal theory-can be reformulated within one language so that we can compare them more directly.     

Weak covering and the tree property

Suppose that there is no transitive model of ZFC + there is a strong cardinal, and let K denote the core model. It is shown that if has the tree property then and is weakly compact in K. Received: 11 June 1997     

Equivalence in Finite-Variable Logics is Complete for Polynomial Time

of first-order logic whose formulas contain at most k variables (for some ). We show that for each , equivalence in the logic is complete for polynomial time. Moreover, we show that the same completeness result holds for the powerful extension of with counting quantifiers (for every ). The k-dimensional Weisfeiler–Lehman algorithm is a combinatorial approach to graph isomorphism that generalizes the naive color-refinement method (for ). Cai, Fürer and Immerman [6] proved that two finite graphs are equivalent in the logic if, and only if, they can be distinguished by the k-dimensional Weisfeiler-Lehman algorithm. Thus a corollary of our main result is that the question of whether two finite graphs can be distinguished by the k-dimensional Weisfeiler–Lehman algorithm is P-complete for each . Received: March 23, 1998