An innovative technology of directional propagation of hydraulic fracture guided by radial holes in fossil hydrogen energy development

Conventional hydraulic fracturing fails to develop low permeability reservoirs of fossil hydrogen energy that are not located in the direction of maximum principal in-situ stress. A new technology of fracture propagation guided by radial holes is proposed, which can realize directional propagation of hydraulic fracture along radial holes in fossil hydrogen energy development. In order to verify this new technology, a model of radial holes combined with hydraulic fracturing is established by the ABAQUS extended finite element method. Simulation results show that radial holes play a guiding role in fractures propagation. The influence extent of seven factors on the directional propagation of hydraulic fracture is listed as follows (from strong to weak): azimuth of radial holes > horizontal in-situ stress difference of fossil hydrogen reservoir > injection rate of fracturing fluid > Young's modulus of rock > permeability of fossil hydrogen reservoir > Poisson ratio of rock > viscosity of fracturing fluid. True tri-axial experiment is carried out to verify the accuracy of numerical simulation, and the result is consistent with numerical model, which indicates that numerical simulation is reliable.     

R-DRA: a replication-based distributed randomized algorithm for data dissemination in connected vehicular networks

Wireless Networks - As data dissemination is of great importance for applications in connected vehicular networks (VANETs), we aim to facilitate the performance of data dissemination in this study....     

Effects of nitric oxide on the alleviation of postharvest disease induced by Penicillium italicum in navel orange fruits

The present study evaluated the effects of 15 μL L^-1 nitric oxide (NO) on the fruit defence response of ‘Newhall’ navel orange. The decay rate of NO-treated navel orange fruits was significantly lower than that of control fruits during storage at 20 °C storage (P < 0.05). Treatment with NO suppressed the increase in disease incidence and lesion area in orange fruits inoculated with Penicillium italicum (P. italicum); significantly increased the activities of phenolic metabolism-associated enzymes and pathogenesis-related (PR) proteins, including polyphenoloxidase (PPO), phenylalanine ammonia-lyase (PAL), β-1,3-glucanase (GLU) and chitinase (CHT); and enhanced the activities of key enzymes, including 4-coumarate: CoA ligase (4CL), cinnamate-4-hydroxylase (C4H) and chalcone isomerase (CHI) in the phenylpropanoid pathway. The contents of total phenolics, flavonoids and lignin were also higher in NO-treated fruits than in control fruits. The findings suggest that exogenous NO could induce disease resistance against P. italicum in navel orange fruits.     

ECOC多类分类研究综述

纠错输出编码能有效地将多类问题转化为二类问题进行求解,已受到国内外从事机器学习的研究者们的重视,并使其成为多类分类领域的研究热点.本文首先分析了ECOC多类分类的原理和框架,指出解决ECOC多类分类问题的关键在于解码策略和编码策略的确定;然后从这两个关键点出发综述了ECOC多类分类的最新进展和应用领域;最后指出了目前存在的问题以及下一步研究方向.论文研究成果将为基于ECOC多类分类方法在实际应用过程中起借鉴和参考作用.     

党政机关网站面临的主要安全问题

党政机关网站是政务公开的重要窗口,代表着党政机关的形象,但其安全问题却日益突出,本文从最常见的安全问题出发,分析了这些问题给党政机关网站带来的危害并提出了相应的解决办法,建议从网站的开发、部署、运维等阶段加强安全控制,保障党政机关网站的安全性。     

冲击波异常数据的分析

文中对存储装置采集的异常冲击波信号进行峰值压力提取.数据通过频谱分析后,采用凯泽窗滤波和平移压力基线的方法进行处理,有效滤除了自激振荡和高频噪声,对比同距测试点冲击波压力峰值,两者一致,有效提取了异常超压的峰值压力.     

基于QEMU的外部总线仿真技术

综合嵌入式系统通过外部总线实现各个子系统之间的通信连接。为解决综合嵌入式系统的接口测试问题,采用系统虚拟机仿真综合嵌入式系统的连接方式,通过在虚拟机中创建外部总线仿真模块,配置仿真模块的连接,从而实现虚拟机之间的通信。提出一种基于以太网通信的外部总线仿真结构,以CAN总线仿真为例,在全系统虚拟机QEMU的内部总线上配置与注册外部总线设备,为读写总线设备数据的接口建立共享内存,组织总线协议报文。实验结果表明,通过网络收发报文,可实现总线仿真节点模块之间的数据交换,从而达到仿真总线的数据通信功能。     

基于数据交换模型的测试方法

通过深入地研究数据交换的通用模型,抽象数据交换的过程状态和规则,提出了一种基于数据交换的测试模型及其测试的方法,该方法能够适用于绝大多数数据交换场景的测试并有效地提高测试效率.最后给出了未来的研究方向.     

精密减速器回差测量的现状与趋势

回差是表征精密减速器性能的关键指标,其定义貌似简单,但蕴含了复杂的测量及评价问题,本文从静态测量和动态测量两个方面论述了当前精密减速器的回差测量原理和方法,对比分析了各种测量方法的异同和优缺点,分析了当前工业领域常用的评价方法,指出评价方法的不同是造成评价结果差异的重要原因。最后指出,建立精密减速器综合性能动态测量系统是适应工业需求的必然趋势,同时当前亟需建立一套完整的精密减速器回差测试规范及评价标准。     

Community Smell Occurrence Prediction on Multi-Granularity by Developer-Oriented Features and Process Metrics

Community smells are sub-optimal developer community structures that hinder productivity.Prior studies performed smell prediction and provided refactoring guidelines from a top-down aspect to help community shepherds.Simultaneously,refactoring smells also requires bottom-up effort from every developer.However,supportive measures and guidelines for them are not available at a fine-grained level.Since recent work revealed developers'personalities and working states could influence community smells'emergence and variation,we build prediction models with experience,sentiment,and development process features of developers considering three smells including Organizational Silo,Lone Wolf,and Bottleneck,as well as two related classes including smelly developer and smelly quitter.We predict the five classes in the individual granularity,and we also generate forecasts for the number of smelly developers in the community granularity.The proposed models achieve F-measures ranging from 0.73 to 0.92 in individual-wide within-project,time-wise,and cross-project prediction,and mean R2 performance of 0.68 in community-wide Smelly Developer prediction.We also exploit SHAP(SHapley Additive exPlanations)to assess feature importance to explain our predictors.In conclusion,we suggest developers with heavy workload should foster more frequent communication in a straightforward and polite way to build healthier communities,and we recommend community shepherds to use the forecasting model for refactoring planning.