Stochastic stabilization of differential systems with general decay rate

Some sufficient conditions concerning stability of solutions of stochastic differential evolution equations with general decay rate are first proved. Then, these results are interpreted as suitable stabilization ones for deterministic and stochastic systems. Also, they permit us to construct appropriate linear stabilizers in some particular situations.     

Web仓储系统的视图刷新方案

1 Web仓储的时新性标准 WWW的迅猛发展使其成为全球信息传递与共享日益重要的信息资源。Web仓储使用物化视图构建信息集成系统,是对Web信息进行充分利用的一种有效方法。Web仓储具有高稳定性,查询速度非常快,非常适合决策分析等需要对信息进行深度加工的应用。与使用虚视图方法进行集成的系统不同,Web仓储系统中的首要任务是物化视图的构建和维护,而视图刷新则是物化视图维护工作的主体。     

关于Razumikhin-Type定理的衰变估计

关于Ｒａｚｕｍｉｋｈｉｎ┐Ｔｙｐｅ定理的衰变估计侯春海钱积新（浙江大学工业控制技术研究所、工业控制技术国家重点实验室３１００２７杭州）关键词Ｒａｚｕｍｉｋｈｉｎ－Ｔｙｐｅ定理，衰变估计．收稿日期１９９６－０９－２７１引言在研究系统的稳定性过程中，专家...     

A New Yellow Long Lasting Phosphor Y2O2S∶Ti

A new kind of doped rare earth free phosphor Y2O2S∶xTi(0＜x≤0.10) with doped Ti as activative center was synthesized by solid state reaction and sintered at 1200 ℃ for 2.5 h under reducing atmosphere. XRD patterns, photoluminescence spectra, time-resolved phosphorescence spectra and decay curves of the phosphor were investigated. XRD results reveal that a single Y2O2S phase exists with Ti content up to 6%(mol fraction). Yellow long lasting phosphorescence for present materials was observed in the dark with naked eye after the removal of the excitation light. From the time-resolved phosphorescence spectra the broad emission band centered at 565 nm was confirmed to be responsible for the long lasting phosphorescence which could maintain above 1 h. The possible mechanism responsible for the long lasting phosphorescence of the Y2O2S∶Ti phosphor was proposed.     

Opto-electronic high-frequency cross-correlation using avalanche photodiodes

Correlation analysis has become an important research tool in the investigation of signals and systems behaviour. We report on a special opto-electronic cross-correlator in which a silicon avalanche photodiode is used as the main component. The internal gain of this photodiode is pulse-modulated with 330 ps FWHM at 126 MHz repetition rate, or is modulated sinusoidally at frequencies of up to 882 MHz, respectively. In the pulsed mode, very weak repetitive optical pulses can be detected with 3 × 10⁻³ photons per pulse sensitivity, and with 10 ps timing accuracy. The second mode offers time-selective signal rejection capabilities with 3 ps time resolution. The opto-electronic cross-correlator can be used in displacement and distance measurement, robotics, time dispersion analysis in optical fibres, transient absorption spectroscopy, fluorescence decay measurement, lifetime-selective fluorescence detection, and in fluorescence signal suppression in Raman spectroscopy.     

Neutron energy dependence of delayed neutron yields and its assessments

Incident neutron energy dependence of delayed neutron yields of uranium and plutonium isotopes is investigated. A summation calculation of decay and fission yield data is employed, and the energy dependence of the latter part is considered in a phenomenological way. Our calculation systematically reproduces the energy dependence of delayed neutron yields by introducing an energy dependence of the most probable charge and the odd–even e?ect. The calculated fission yields are assessed by comparison with JENDL/FPY-2011, delayed neutron activities, and decay heats. Although the fission yields in this work are optimized to delayed neutron yields, the calculated decay heats are in good agreement with the experimental data. Comparison of the fission yields calculated in this work and JENDL/FPY-2011 gave an important insight for the evaluation of the next Japanese evaluated nuclear data library (JENDL) .     

一种新型溴化铈闪烁体探测器性能研究

闪烁探测器在射线能量与时间的探测中发挥着重要作用。针对国产新型溴化铈（CeBr₃）闪烁晶体，本文建立实验系统和方法对其关键性能指标进行了测试，具体包括：建立了快符合时间分辨系统测量装置，测试得到新型闪烁探测器对于⁶⁰Co源的时间分辨率为142 ps；建立了单光子计数法测量装置，测试得到溴化铈晶体的衰减时间为16.8 ns，上升时间为0.18 ns；建立了相对光输出测量装置，测试得到其相对于同规格NaI(Tl)闪烁体探测器对于661.66 keV射线的光输出为161%；同时针对其能量响应性能进行了测试，测得对于661.66 keV射线其能量分辨率为4.7%。将国产新型溴化铈闪烁晶体的性能测试结果与国际上同类晶体以及氟化钡、溴化镧、碘化钠等常用无机闪烁体的性能进行了比较，对其应用前景进行了探讨。     

Evaluation of decay photocurrent measurements in dye‐sensitized solar cells: Application to laser beam‐induced current technique

The use of the laser beam‐induced current (LBIC) technique in photovoltaic devices is widespread, but its use in photoelectrochemical cells, such as dye‐sensitized solar cells (DSSCs), is limited due to the configuration of these devices. The main reason is the very slow response time of DSSCs in the decay process, and therefore LBIC scans take too long to perform. We have designed a procedure published in the literature to correct the photocurrent values obtained by the LBIC technique, based on an algorithm that uses a decreasing mono‐exponential model. This work presents a study of the decay measurements in DSSCs using several functions, in order to improve the algorithm designed. It concludes that functions such as a decreasing bi‐exponential or Becquerel function generate better fits to experimental data. Copyright © 2010 John Wiley & Sons, Ltd.     

横向简谐荷载作用下端锚黏结式锚杆黏结性试验研究

由于采动荷载和爆破荷载对已有支护锚杆产生影响，因此迫切需要研究锚杆在动荷载作用下的微观力学特性及黏结性变化。从工程实际出发，现场监测锚杆工作状态下轴力变化和爆破荷载作用下锚杆周边围岩振动信息，并开展探索性室内试验。通过室内试验获得锚杆在轴向荷载作用下横向固有频率振动后的振动强度与工作龄期耦合作用下锚杆黏结性衰减规律的拟合计算式。研制了横向简谐荷载作用下端锚黏结式锚杆模型试验装置，采用均匀设计方法，考虑锚杆长度和锚杆直径两个影响因素，通过动态监测系统获得了横向简谐荷载作用下锚杆应力沿锚杆长度的分布规律、锚杆应力分布与拉拔力的关系，以及剪切应力与位移的关系。最终采用大型有限差分软件FLAC3D，建立了锚杆与围岩相互作用的力学模型。     

Estimation of bitumen emulsion dispersion using a light scattering method

Petroleum bitumen in the emulsified state is widely used as a binder in road and civil construction. Along with traditional quality parameters of bitumen emulsions the particle size is considered to be very important characteristic. The particle size of the dispersed phase affects the setting rate and viscosity of bitumen emulsions. The complete data on the particles size distribution can be obtained using such technical methods as light scattering and microscopy. In the study bitumen emulsions with three types of surfactants (cationic, nonionic, zwitterionic) have been prepared and their viscosity and decay index have been determined. The emulsions also have been studied with a microscope, as well as by the method of dynamic light scattering. The dynamics of particle size changes of the bitumen emulsions has been compared with the dynamics of the change in the basic parameters of the emulsions, such as viscosity and decay index, and the correlation between them has been found. Thus, using a modern laser and optical equipment, it is possible to estimate the quality of emulsions and, if necessary, to correct their composition.