饱水石灰岩骨架和流体弹性参数的估算

本文利用Niu等提出的基于临界孔隙度模型的组分弹性参数数值计算方法,把测试岩石样品的孔隙度、整体密度、纵波速度和横波速度作为数值计算的输入数据,运用双线性数值计算方法反演求出临界点、流体和骨架的12个弹性参数。具体做法是:基于临界孔隙度模型,给出三组线性关系,即密度—孔隙度,整体剪切模量—孔隙度,整体纵波模量—孔隙度,上述每组线性关系分别以孔隙度作为自变量和因变量得到两个线性方程,再把两个方程计算的结果进行加权平均得到相关的弹性参数估算值,并结合饱水石灰岩样品数据实现了弹性参数估算。数值计算结果表明,由数值计算得到的弹性参数与测试弹性参数的均值和方差相差甚微,特别是密度数据的偏差均值更小,说明文中的数值计算结果是可靠的。     

电子文件档案化管理研究

随着电子信息技术的飞速发展和办公自动化程度的不断提高,大量的电子文件逐步成为记录人类社会活动的重要载体,这就使得电子文件档案化管理成为档案工作发展的必然趋势.回顾了电子档案的产生和特点,分析了电子档案的优势和弊端,并以国内外对于电子文件档案化管理方法的研究为基础,结合实际经验,总结并提出了电子文件档案化管理的原则和对策.     

苯胍胺改性三聚氰胺甲醛树脂的合成研究

以NaOH为催化剂,在反应温度不超过90℃下,苯胍胺的加入可以改善三聚氰胺甲醛树脂体系的贮存稳定性,但树脂的固含量、黏度等指标与树脂的贮存稳定性没有明显的规律可循。作为发泡材料用树脂,树脂的固含量为90%左右时,发泡效果最好。     

Stochastic stability of quasi-integrable Hamiltonian systems with time delay by using Lyapunov function method

The asymptotic Lyapunov stability of one quasi-integrable Hamiltonian system with time-delayed feedback control is studied by using Lyapunov functions and stochastic averaging method.First,a quasi-integrable Hamiltonian system with time-delayed feedback control subjected to Gaussian white noise excitation is approximated by a quasi-integrable Hamiltonian system without time delay.Then,stochastic averaging method for quasi-integrable Hamiltonian system is used to reduce the dimension of the original system,a...     

静压PHC管桩施工问题分析与讨论

静压PHC管桩在福建省内广泛采用,本文描述静压PHC管桩在施工中常见的问题及处理方法,并以四季康城为施工实例,介绍其施工技术和质童控制,给相关部门提供参考,提高我国静压PHC管桩的管理水平。     

Amplifier linearization using compact microstrip resonant cell-theory and experiment

This paper presents a novel technique for reducing the intermodulation distortions (IMDs) in power amplifiers. In this method, both second- and third-harmonic components generated by the transistor are reflected back simultaneously by the compact microstrip resonant cell (CMRC) at the input port with proper phases to mix with the fundamental signal for the reduction of IMDs. A rigorous mathematical analysis on the effectiveness of multiharmonic reflections has been formulated and derived using the Volterra series. Moreover, the delay mismatch factor of the proposed method is analytically studied and the result shows that a better tolerance to the delay error can be achieved by using CMRC circuitry. Standard two-tone test measurements reveal 32- and 22-dB reductions for the third-order IMD and fifth-order IMD, respectively, without affecting the fundamental signal at 2.45 GHz. Meanwhile, the proposed approach gives a peak power added efficiency of 53% with 11.5 dB transducer gain and 15 dBm output power for a single-stage SiGe bipolar junction transistor. The adjacent channel power ratio (ACPR) is -55dBc for a data rate of 384-kb/s quadrature phase shift keyed modulated signal with 2-MHz spanning bandwidth, and this ACPR is maintained for a broad range of output power level.     

Asymptotic loss of real-time traffic in wireless mobile networks with selective-repeat ARQ

We study the issue of quality of service (QoS) for real-time traffic over a wireless channel deploying automatic repeat request (ARQ) error control. An analytical model has been derived to evaluate the queueing related loss and the wireless channel related loss. In contrast to previous work, this model quantifies the interaction between the network layer and the physical layer, and then it enables the admission controllers of wireless networks to improve utilization while satisfying the traffic QoS constraints through cross-layer design techniques.     

复杂流场的激光—超声测试方法及原理性实验研究

本文从复杂流场-旋涡场参量的激光-超声测试方法的需要出发,论述了超声波产生的声位相光栅对激光产生的衍射及偏转特性。在水中进行了声光偏转等试验,测出了产生声光偏转时折射率的变化及声压变化,从而估算出空气复杂流场激光——超声方法所需的超声频率及能量,为实现空气流场激光——超声无接触测试的研究提供了依据。     

Photonic sensor with radio frequency power detection for body pressure monitoring

A photonic sensor with radio frequency(RF) power detection for body pressure monitoring is proposed. The sensor based on two fiber Bragg gratings(FBGs) can transfer the wavelength shift to the change of RF power. The pressure can be measured by modulating and processing one single frequency RF signal. The theoretical analysis and experimental results of the photonic sensor are presented and discussed. The pressure sensitivities are acquired with 2.62×10^-5 mW/kPa at 2.14 GHz, 2.46×10