无线通信基站检测在无线电管理中发挥的重要作用

对GSM无线通信基站的技术参数测试目的和作用进行论述,有助于无线电管理者和通信运营商全面掌握基站的发射特性,保证正常的无线电电波秩序和良好的移动通信质量。     

不同活化方法对天然硅铝矿物活化及分子筛合成效果的影响

选取了高岭土、累托土、蒙脱土和伊利石四种天然硅铝矿物,采用热活化、碱熔活化、亚熔盐活化及拟固相活化四种方法对上述四种矿物分别进行活化,对比了不同活化方法对天然硅铝矿物活化效果的影响。结果表明,亚熔盐活化及拟固相活化都具有良好的活化效果,而且能耗较低,明显优于热活化和碱熔活化。其中,拟固相活化由于能耗更低且更有利于实现工业操作,因此,是最具发展前景的天然硅铝矿物活化方法。对比四种天然硅铝矿物,高岭土、累托土及蒙脱土的晶相结构更容易被解聚,而伊利石稳定性更高,经亚熔盐活化及拟固相活化后,活化产物中也只有极少量的高反应活性的硅、铝物种,因此,伊利石不是理想的分子筛合成原料。     

探讨基于场景的WLAN网络无线优化策略

近几年来,无线网络的使用和覆盖范围迅速扩张,如何优化无线网络通信质量,提高无线网络覆盖效率,这是各大运营商赢得网络核心竞争力的关键所在。文章主要介绍了一种基于场景的WLAN网络无线优化策略,并且从三种比较典型的WLAN场景角度出发,结合相应的关键参数分析了几个具有代表性的优化案例及措施。     

L-色氨酸与α/β-环糊精结合机理的计算研究

本研究通过分子动力学模拟详细探讨α/β-环糊精(α/β-CD)与L-色氨酸(L-Trp)在水溶液环境下的相互作用.通过利用MM/PBSA方法计算结合自由能,表明α/β-CD在水溶液中能够自发的与L-Trp络合,并且β-CD与L-Trp结合能力更强.通过观察α/β-CD与L-Trp的动态结合过程,并计算氢键数量,CD空腔...     

2-甲基-5-(2-吡啶基)-1,3,4-噁二唑Cu(II),Cd(II)配合物的合成,晶体结构和表征

以2-甲基-5-（2-吡啶基）-1,3,4-噁二唑（L）为配体合成了[Cu₂L₂（μ-Cl）₂Cl₂]（1）和[CdL₂（NO₃）₂]（2）,测定了X射线单晶结构,用红外光谱、紫外光谱、荧光及热重分析进行了表征。配体L和配合物2属于单斜晶系,配合物1属于三斜晶系。L,1和2的空间群分别为P2₁/c,P1和C2/c。配合物1是通过2个氯原子（Cl1,Cl1ⁱ）桥联形成的双桥双核Cu(II)配合物,具有畸变四方锥构型[CuCl₃N₂]。配合物2具有畸变八面体构型[CdN₄O₂]。     

Elastic Scattering of 6He + p at 82.3MeV/nucleon

Differential cross sections for the elastic scattering of halo nucleus 6He on proton target were measured at 82.3 MeV/u. The experimental results axe well reproduced by optical model calculations using global potential KD02 with a reduction of the depth of real volume part by a factor of 0.7. A systematic analysis shows that this behavior might be related to the weakly bound property of unstable nuclei.     

Spectroscopic properties in Er3＋/yb3＋ Co-doped fluorophosphate glass

Using the technique of high-temperature melting, a new Er3＋/Yb3＋ co-doped fluorophosphate glass was prepared. The absorption and fluorescence spectra were investigated in depth. The effect of Er3＋ and Yb3＋ concentration on the spectroscopic properties of the glass sample was also discussed. According to the Judd Ofelt theory, the oscillator strength was computed. The lifetime of 4113/2 level （t-m） of Er3＋ ions was 8.23 ms, and the full width at half maximum of the dominating emission peak was 68 nm at 1.53 μm. The large stimulated emission cross section of the Er3＋ was calculated by the McCumher theory. The spectroscopic properties of Er3＋ ion were compared with those in different glasses. The full width at half maximum and σe are larger than those of other glass hosts, indicating this studied glass may be a potentially useful candidate for high-gain erbium-doped fiber amplifier.     

自适应在线模型校准的RSS实时定位算法*

针对传统的RSS定位方法对环境因素要求过高,在设计校准和运行操作阶段工作量大效率不高的问题,提出一种基于锚节点RSS在线建模校准的无线传感器网络定位算法。首先,利用标准偏差阈值方法对信号强度不确定度较大的锚节点进行过滤,并对锚节点和未知节点间的距离与接收信号强度的关系进行在线建模。其次,采用周期校准方式对在线模型进行实时修正,然后利用加权平均的方式对未知节点进行定位,建立对环境因素的自适应机制实现节点的实时准确定位。最后,通过仿真显示该方法能够有效对无线传感器网络未知节点进行定位且精度满足要求,算法简单易于实现具有实际应用价值。     

Monte Carlo simulation of the property of a scintillation bar in the multi-neutron correlation spectrometer

To perform a kinematically complete measurement of the dissociation reaction for neutron-rich nuclei, a multi-neutron correlation spectrometer is proposed at Peking University. A Monte Carlo simulation code based on GEANT4 is developed for a single scintillation bar which processes not only the energy deposition but also the light propagation in the scintillator and the light collection and conversion to signal at the end of the bar in a realistic way. The simulating method is described in detail in this paper, and the timing and position resolutions and detector efficiency are studied based on the simulation and compared with the experimental results. A new method of crosstalk rejection has been demonstrated to be important for the design of the whole spectrometer.     

RIBLL终端大面积中子探测器阵列研制方案的理论计算

介绍了一种用于丰中子核研究的RIBLL终端大面积中子探测器阵列的研制.利用Geant4软件包对该探测系统的中子探测效率、时间分辨和位置分布等进行了蒙特卡罗模拟,同时对探测器的cross?talk进行了研究.给出了探测器的设计方案.