小波变换的地下含水层分层法

根据电测井曲线可以了解地层构造.为了找出含水砂层,基于人工分层的原理,利用小波变换过零点理论对电测井曲线进行计算机自动分层,将地下土层分为含水层和隔水层.介绍小波变换原理,给出用Matlab软件实现测井曲线计算机自动分层的方法.实验结果表明,用该方法研究实测井信号,结果与人工方法基本一敛,证明了小波变换用于测井信号分析与处理的有效性.论文工作对合理利用地下水资源有非常重要的意义.     

A Phase Engineering Strategy of Perovskite-Type ZnSnO3:Nd for Boosting the Sonodynamic Therapy Performance

The sensitization performance of sonosensitizers plays a key role in the sonodynamic therapy (SDT) effect. Herein, ZnSnO₃:Nd nanoparticles with R3c phase/amorphous heterogeneous structure are developed by phase engineering strategy and applied as an ideal sonosensitizer. In the crystalline perovskite-type ZnSnO₃:Nd, the substitution of the Zn²⁺ with Nd³⁺ causes the O 2p non-bonded state to move toward the Fermi level, which optimizes the band structure for ultrasound sensitization by reducing bandgap. Meanwhile, the unequal charge substitution can also form electron traps and oxygen vacancies to shorten the electron migration distance, which accelerates the electron–hole separation and inhibits carrier recombination, thus improving the acoustic sensitivity. Moreover, the dangling bonds exposed on the surface of amorphous ZnSnO₃:Nd provide more active sites, and the localized states of the amorphous phase may also promote carrier separation, resulting in synergistic SDT effect. In particular, the Zn²⁺ released from ZnSnO₃:Nd in the acidic tumor microenvironment (TME) reduces the adenosine triphosphate production by inhibiting the electron transport chain , which promotes the tumor cell apoptosis through destroying the redox balance of TME. Combining the inherent second near infrared and computed tomography imaging capabilities, this ZnSnO₃:Nd nanoplatform shows a promising perspective in clinic SDT field.     

A d-axis based current differential protection scheme for an active distribution network

The emergence of distributed generators has changed the operational mode and fault characteristics of the distribu tion network, in a way which can severely influence protection. This paper proposes a d-axis-based current differential protection scheme. The d-axis current characteristics of inverter-interfaced distributed generators and synchronous generators are analyzed. The differential protection criterion using sampling values of the d-axis current component is then constructed. Compared to conventional phase-based current differential protection, the proposed protection reduces the number of required communication channels, and is suitable for distribution networks with inverter interfaced distributed generators with complex fault characteristics. Finally, a 10 kV active distribution network model is built in the PSCAD platform and protection prototypes are developed in RTDS. Superior sensitivity and fast speed are verified by simulation and RTDS-based tests.     

Edge Fracture Prediction Using Uncoupled Ductile Fracture Models for DP780 Sheet

This paper is a contribution to the prediction of edge fracture behavior using uncoupled ductile fracture models. A fully integrated simulation framework for the edge fracture prediction is proposed with the shear-induced pre-damage considered. User-defined material subroutines are coded with uncoupled ductile fracture models (Lou-Huh, Oh, Brozzo) incorporated, which are calibrated using the fracture strains of various loading paths. A series of 3D numerical simulations are performed and compared with the results of hole-expansion tests. The effects of pre-damage field and fracture models are analyzed and discussed.

     

冷凝式天然气快速热水器的应用探讨

根据对冷凝式燃气快速热水器节能效果的理论分析,产通过试验得出冷凝式天然气快速热水器热效率与其排烟温度的关系,试验结果表明冷凝式天然气快速热水器有很好的实用价值。     

Asymptotic powers for matched trend tests and robust matched trend tests in case-control genetic association studies

The matched trend test (MTT), developed using a conditional logistic regression, has been proposed to test for association in matched case-control studies to control the bias of known confounding effects and reduce the potential impact of population stratification. The MTT requires a known genetic model. When the genetic model is unknown, a Monte Carlo robust test, MAX, has been proposed for the analysis of matched case-control studies. The MAX statistic takes the maximum of three MTTs optimal for three common genetic models. We derive the asymptotic power for MTTs and robust tests. In particular, we derive the asymptotic p-value for MAX. Using these analytical results, we conduct simulation studies to compare the performance of MAX and the two-degree-of-freedom Chi-square test for matched case-control studies, where the latter is implemented in most computing software. Our simulation results show that MAX is always asymptotically more powerful than the two-degree-of-freedom Chi-square test under common genetic models. Our results provide guidelines for the analysis of genetic association using matched case-control data. An illustration of our results to a real matched pair case-control etiologic study of sarcoidosis is given.     

A hybrid immune model for unsupervised structural damage pattern recognition

This paper presents an unsupervised structural damage pattern recognition approach based on the fuzzy clustering and the artificial immune pattern recognition (AIPR). The fuzzy clustering technique is used to initialize the pattern representative (memory cell) for each data pattern and cluster training data into a specified number of patterns. To improve the quality of memory cells, the artificial immune pattern recognition method based on immune learning mechanisms is employed to evolve memory cells. The presented hybrid immune model (combined with fuzzy clustering and the artificial immune pattern recognition) has been tested using a benchmark structure proposed by the IASC–ASCE (International Association for Structural Control–American Society of Civil Engineers) Structural Health Monitoring Task Group. The test results show the feasibility of using the hybrid AIPR (HAIPR) method for the unsupervised structural damage pattern recognition.     

FW与IDS联动技术在Intranet中的应用研究

互联网技术的发展带动了众多新型网络产业的出现.针对新型网络公司业务运营要求实现系统安全技术的特点,设计和实现了一种防火墙与入侵检测联动的系统.该系统通过联动把实时、快速和自适应的动态安全技术作为静态防火墙技术的有效补充,为静态防火墙技术的包过滤、信任检查和访问控制的动态更新提供了技术保障.使远程控制的无人值守机房的网络系统安全问题得到了有效解决.     

一种新型的FPGA实现RS422串口通信方法

在FPGA实现RS422串口通信的常用方法中经常遇到诸多问题,如FIFO深度读取不正确、FIFO写数据端口与读数据端口时序竞争、多个模块间信号延时导致FPGA亚稳态等问题,因此设计了一种新型的RS422串口通信实现方法;该方法通过利用寄存器数组作为循环缓存代替FIFO,利用计数器代替传统的波特率产生模块,把常用方法中的多个模块整合成一个模块,只采用一个主时钟,所有寄存器的时钟输入端共享一个时钟,对FPGA逻辑与时序进行了有效约束,避免了FPGA中亚稳态产生;试验结果表明该方法实现的RS422串口通信高速、可靠、稳定,并且利用FPGA实现RS422串口通信,可使整个系统更为灵活、紧凑,减小整个电路的体积,提高系统的可靠性和稳定性。