期刊文献+
共找到3,299篇文章
< 1 2 165 >
每页显示 20 50 100
Fasciola worm and egg-derived antigens:Exploring their diagnostic potential for urogenital schistosomiasis in resource-limited endemic regions
1
作者 Adedayo Adesida Tajudeen Oriade +7 位作者 Kabirat Sulaiman Funmilayo Afolayan Timothy Auta Ibikunle Akanbi Mercy Aladegboye Roseangela Nwuba Alexander Odaibo Oyetunde Oyeyemi 《Asian Pacific Journal of Tropical Medicine》 SCIE CAS 2024年第11期501-507,I0029,共8页
Objective:To evaluate the immunodiagnostic potential of crude Fasciola gigantica-worm(FWA)and egg antigen(FEA)in detecting anti-Schistosoma(S.)haematobium antibodies in sera and urine samples.Methods:This is a cross-s... Objective:To evaluate the immunodiagnostic potential of crude Fasciola gigantica-worm(FWA)and egg antigen(FEA)in detecting anti-Schistosoma(S.)haematobium antibodies in sera and urine samples.Methods:This is a cross-sectional diagnostic study.Employing an indirect ELISA,antibodies against these antigens were assessed in samples from infected and non-infected individuals in both schistosomiasis endemic(NE)and non-endemic(NNE)areas,using microscopy as the diagnostic standard.Results:FWA-sera exhibited excellent diagnostic accuracy with an area under the curve(AUC)of 0.957,a sensitivity of 93.75%,and a specificity of 85.42%for discriminating between infected and non-infected individuals in non-endemic areas.FWA-urine also demonstrated robust performance,achieving AUC>0.95,sensitivity>97.0%,and specificity>85.0%in both NE and NNE categories.Notably,S.haematobium-specific antibody levels against FWA were significantly elevated in infected individuals in both endemic and non-endemic areas.FEA-sera exhibited outstanding diagnostic performance with sensitivity exceeding 90%and an AUC of 0.968 in non-endemic samples but not in FEA-urine.Conclusions:FWA-based ELISAs,applicable to both sera and urine,emerge as promising tools for S.haematobium diagnosis in resource-limited settings,offering advantages of high sensitivity and specificity with shared antigens with Fasciola.The superior diagnostic metrics of urine samples suggest their potential as a non-invasive biological sample for diagnostic purposes. 展开更多
关键词 Schistosoma haematobium Non-invasive worm antigen ELISA Immuno-diagnosis
下载PDF
A blockchain-empowered authentication scheme for worm detection in wireless sensor network
2
作者 Yuling Chen Xiong Yang +2 位作者 Tao Li Yi Ren Yangyang Long 《Digital Communications and Networks》 SCIE CSCD 2024年第2期265-272,共8页
Wireless Sensor Network(WSN)is a distributed sensor network composed a large number of nodes with low cost,low performance and self-management.The special structure of WSN brings both convenience and vulnerability.For... Wireless Sensor Network(WSN)is a distributed sensor network composed a large number of nodes with low cost,low performance and self-management.The special structure of WSN brings both convenience and vulnerability.For example,a malicious participant can launch attacks by capturing a physical device.Therefore,node authentication that can resist malicious attacks is very important to network security.Recently,blockchain technology has shown the potential to enhance the security of the Internet of Things(IoT).In this paper,we propose a Blockchain-empowered Authentication Scheme(BAS)for WSN.In our scheme,all nodes are managed by utilizing the identity information stored on the blockchain.Besides,the simulation experiment about worm detection is executed on BAS,and the security is evaluated from detection and infection rate.The experiment results indicate that the proposed scheme can effectively inhibit the spread and infection of worms in the network. 展开更多
关键词 Wireless Sensor Network(WSN) Node authentication Blockchain TANGLE worm detection
下载PDF
侧链含有不同电子受体的聚咔唑衍生物的合成及其WORM型存储性能 被引量:1
3
作者 刘柳 程庆 +2 位作者 樊菲 张斌 陈彧 《功能高分子学报》 CAS CSCD 北大核心 2016年第2期163-171,181,共10页
利用Suzuki偶联反应合成了3种侧链含有不同电子受体的可溶性D-A型聚咔唑衍生物:聚[(9-(2-己基葵基)-9 H-咔唑)-(9-(4-硝基苯基)-9 H-咔唑)](PCz-NO2)、聚[(9-(2-己基葵基)-9 H-咔唑)-(4-(9 H-咔唑-9-基)苯甲醛)](PC... 利用Suzuki偶联反应合成了3种侧链含有不同电子受体的可溶性D-A型聚咔唑衍生物:聚[(9-(2-己基葵基)-9 H-咔唑)-(9-(4-硝基苯基)-9 H-咔唑)](PCz-NO2)、聚[(9-(2-己基葵基)-9 H-咔唑)-(4-(9 H-咔唑-9-基)苯甲醛)](PCz-CHO)和聚[(9-(2-己基葵基)-9 H-咔唑)-(4-(9 H-咔唑-9-基)苯甲腈)](PCz-CN)。基于这3种聚合物的存储器件(器件结构:Al(200nm)/高分子(90nm)/氧化铟锡(ITO)均表现出典型的电双稳电子开关效应和非易失性一次写入多次读出(WORM)型存储性能。随着共轭聚合物光学带隙的增加[2.26eV(PCz-NO2)→2.79eV(PCzCHO)→3.20eV(PCz-CN)],相应器件的启动阈值电压逐渐增大(-1.70V→-1.81V→-1.89V);而电流开关比(ON/OFF)则依次减小(6.63×10^4→4.08×10^4→5.68×10^3)。含氰基的聚咔唑衍生物需要的开启电压最大,展现出来的电流开关比在3种聚合物中则最小。 展开更多
关键词 聚咔唑 D-A型共轭聚合物 worm型存储器件 阈值电压 电流开关比
下载PDF
水丝蚓(Tubificid worms)扰动对磷在湖泊沉积物-水界面迁移的影响 被引量:35
4
作者 张雷 古小治 +4 位作者 王兆德 申秋实 范成新 钟继承 尹洪斌 《湖泊科学》 EI CAS CSCD 北大核心 2010年第5期666-674,共9页
为探讨水丝蚓(Tubificid worms)扰动对磷在湖泊沉积物-水界面间迁移的影响,选取太湖梅梁湾与大浦口两富营养化湖区为研究对象,通过室内培养实验,利用Rhizon间隙水采样器等技术,研究了水丝蚓扰动对太湖沉积物-水界面理化性质及溶解活性磷... 为探讨水丝蚓(Tubificid worms)扰动对磷在湖泊沉积物-水界面间迁移的影响,选取太湖梅梁湾与大浦口两富营养化湖区为研究对象,通过室内培养实验,利用Rhizon间隙水采样器等技术,研究了水丝蚓扰动对太湖沉积物-水界面理化性质及溶解活性磷(SRP)在界面通量的影响.结果表明水丝蚓扰动能够增大表层沉积物含水率、氧化还原电位,减小间隙水中Fe2+浓度.水丝蚓没有显著改变梅梁湾间隙水中SRP浓度,同时促进了梅梁湾沉积物中SRP向上覆水的释放;但水丝蚓显著减小了大浦口间隙水中SRP浓度,并抑制了大浦口沉积物中SRP向上覆水的释放.水丝蚓扰动对磷在沉积物-水界面间迁移的不同影响可能是由沉积物中Fe2+含量差异较大造成的. 展开更多
关键词 生物扰动 磷迁移 二价铁 太湖 水丝蚓 梅梁湾 大浦口
下载PDF
WORM存储技术及其在医院中的应用 被引量:3
5
作者 徐浩 辛海燕 楚宏硕 《医疗设备信息》 2006年第8期25-28,34,共5页
本文简要介绍了WORM存储技术的基本概念,指出了基于光盘、磁带和磁盘的WORM技术的实现方法和各自的优缺点,讨论了医疗信息的特征和在医院信息化建设中应用WORM存储技术的必要性和迫切性,并给出了在医院中运用WORM技术的设计方案和应注... 本文简要介绍了WORM存储技术的基本概念,指出了基于光盘、磁带和磁盘的WORM技术的实现方法和各自的优缺点,讨论了医疗信息的特征和在医院信息化建设中应用WORM存储技术的必要性和迫切性,并给出了在医院中运用WORM技术的设计方案和应注意的问题。 展开更多
关键词 worm 存储 光盘 磁带 磁盘 医疗信息 医院信息化
下载PDF
Contact Toxicity and Antifeedant Activity of Aconitum flavum Extract against Cabbage Worm
6
作者 梁永锋 刘立红 +1 位作者 刘世巍 丁建海 《Plant Diseases and Pests》 CAS 2010年第6期58-60,72,共4页
[ Objective] The paper was to study the contact toxicity and antifeedant activity of Aconitum flavum against cabbage worm. [ Method ] In- sect dipping method was adopted to determine the contact toxicity of the extrac... [ Objective] The paper was to study the contact toxicity and antifeedant activity of Aconitum flavum against cabbage worm. [ Method ] In- sect dipping method was adopted to determine the contact toxicity of the extracts of A. fiavum extracted from five polar solvents including ethanol, petroleum ether, ether, ethyl acetate, n-butanol and water; leaf dish method was adopted to determine the antifeedant activities of five solvent ex- tracts including ethanol, petroleum ether, ether, ethyl acetate, n-butanol and water against cabbage worm, [ Result] Extracts of A. flavum had high contact toxicity against cabbage worm. When the concentration was 100.00 mg/ml, the corrected mortality at 48 h roached 97.24%, and the insec- ticidal activities of five solvent extracts against cabbage worm in sequence were water 〉 n-butanol 〉 ethyl acetate 〉 ether 〉 petroleum ether, the cor- rected mortality of water extract at 48 h was 95.87% ; the antifeedant activities of five solvent extracts in sequence were water 〉 n-butanol 〉 ethyl ac- etate 〉 ether 〉 petroleum ether. [ Conclusion] Extracts of A. flavum had strong contact toxicity and antifeedant activity against cabbage worm, and the active ingredients with contact toxicity and antifeedant activity might be a kind of polar compound. 展开更多
关键词 Aconitum flavum EXTRACT Cabbage worm Contact toxicity Antifeedant activity
下载PDF
一种WORM光盘文件存储系统的设计
7
作者 杨建东 布鲁诺.瑞斯曼 裴先登 《小型微型计算机系统》 CSCD 北大核心 1996年第3期47-51,共5页
本文讨论了WORM光盘构成文件存储系统时由于写一次特性引起的各种处理方式。给出了一种存档后备式文件系统的设计。详细说明了其层次结构、文卷结构、文件结构,以及用户界面、层内部界面等设计。同时给出了速度及可靠性的设计考虑。
关键词 worm光盘 文件存储系统 设计 光盘存储器
下载PDF
模拟Worms的游戏设计与实现
8
作者 陈英雪 王显德 《吉林化工学院学报》 CAS 2013年第1期64-69,共6页
本课题的目标是仿照Team17的Worms2D系列游戏产品,开发一款2D游戏,了解整个游戏开发流程,设计一款2D游戏引擎,封装了Direct3D9的部分图形绘制接口、图形控制接口、音效接口,并在此基础上实现一款2D射击游戏.
关键词 DIRECT 3D worm 接口
下载PDF
Win32.SQLExp.Worm蠕虫病毒分析与对策
9
作者 杨斌 聂伟强 《计算机与现代化》 2003年第12期62-64,共3页
分析了Win32.SQLExp.Worm蠕虫病毒原理,并给出相应解决方案。
关键词 蠕虫病毒 Win32.SQLExp.worm 缓冲区溢出 计算机病毒 网络安全 防火墙
下载PDF
第二代光盘——WORM
10
作者 郑登理 《情报学报》 CSSCI 北大核心 1991年第2期144-150,共7页
关键词 光盘 worm 情报载体
下载PDF
WORMS评分中滑膜炎症与膝骨性关节炎中医证型的关联性研究 被引量:14
11
作者 顾庾国 姜宏 《中国骨伤》 CAS CSCD 2019年第12期1108-1111,共4页
目的:探讨膝骨性关节炎性滑膜炎与膝骨关节炎中医证型的相关性。方法:自2015年1月至2018年6月,选取213例膝骨关节炎的患者,进行中医辨证分型,其MRI影像进行WORMS评分,同时做WORMS评分中滑膜炎和中医证型的相关性分析。结果:213例患者中... 目的:探讨膝骨性关节炎性滑膜炎与膝骨关节炎中医证型的相关性。方法:自2015年1月至2018年6月,选取213例膝骨关节炎的患者,进行中医辨证分型,其MRI影像进行WORMS评分,同时做WORMS评分中滑膜炎和中医证型的相关性分析。结果:213例患者中,风寒湿痹证25例(占11.7%),风湿热痹证84例(占39.4%),瘀血痹阻证43例(占20.2%),肝肾亏虚证61例(占28.6%);在WORMS评分中,滑膜炎评分为0分的12例(占5.6%),1分的60例(占28.2%),2分的50例(占23.5%),3分的91例(占42.7%);相关性分析中,差异有统计学意义,WORMS评分中滑膜炎3分组更容易发生在风湿热痹证中(χ^2=137.286,P=0.000)。结论:膝骨性关节炎滑膜炎患者临床上以风湿热痹型(39.4%,84/213)为主,这对于相关治疗有一定的指导意义。 展开更多
关键词 骨关节炎 滑膜炎 辨证分型 wormS评分
下载PDF
介孔Worm-like孔壁晶化制备微孔-介孔分子筛研究
12
作者 徐玲 张强 +5 位作者 陈衍川 周耿旭 高新 张淼 李丹丹 刘宗瑞 《大连理工大学学报》 EI CAS CSCD 北大核心 2018年第6期559-563,共5页
采用水热孔壁晶化法,以Worm-like介孔分子筛为硅源,十八水合硫酸铝为铝源,制备不同硅铝比微孔-介孔ZSM-5复合分子筛,XRD、FT-IR、N2吸附-脱附、TEM等表征结果证明,用此方法成功制备出一系列微孔-介孔ZSM-5复合分子筛.将一系列复合分子... 采用水热孔壁晶化法,以Worm-like介孔分子筛为硅源,十八水合硫酸铝为铝源,制备不同硅铝比微孔-介孔ZSM-5复合分子筛,XRD、FT-IR、N2吸附-脱附、TEM等表征结果证明,用此方法成功制备出一系列微孔-介孔ZSM-5复合分子筛.将一系列复合分子筛用于催化苯酚叔丁基化反应,在反应温度145℃、n(苯酚)∶n(叔丁醇)=1∶2.5条件下,硅铝比为15、25的复合分子筛有较强的催化活性,苯酚转化率和2,4-二叔丁基苯酚选择性分别超过90%和42%. 展开更多
关键词 微孔-介孔分子筛 worm-like介孔分子筛 孔壁晶化 催化性能
下载PDF
Worm-like分子筛负载磷钨酸催化剂的制备及光降解甲基橙的性能研究 被引量:4
13
作者 美春 王月林 +1 位作者 徐玲 刘宗瑞 《环境污染与防治》 CAS CSCD 北大核心 2014年第12期27-30,共4页
以Worm-like分子筛为载体,采用浸渍法制备不同磷钨酸负载量的负载型催化剂,并采用傅里叶红外光谱(FT-IR)、X射线衍射(XRD)和N2吸附/脱附等手段对负载型磷钨酸催化剂进行表征。结果表明,磷钨酸成功负载在Worm-like分子筛上,且随着磷钨酸... 以Worm-like分子筛为载体,采用浸渍法制备不同磷钨酸负载量的负载型催化剂,并采用傅里叶红外光谱(FT-IR)、X射线衍射(XRD)和N2吸附/脱附等手段对负载型磷钨酸催化剂进行表征。结果表明,磷钨酸成功负载在Worm-like分子筛上,且随着磷钨酸负载量的增加,FT-IR、XRD和N2吸附/脱附结果呈规律性变化。将该系列催化剂用于光催化降解甲基橙实验,结果表明,甲基橙质量浓度为20mg/L,磷钨酸负载量为70%(质量分数)时,甲基橙降解率为87.2%;回收催化剂并重复使用3次,甲基橙降解率仍达75%以上。 展开更多
关键词 光催化 worm-like分子筛 甲基橙
下载PDF
Parametric Analysis of the End Face Engagement Worm Gear 被引量:11
14
作者 DENG Xingqiao WANG Jueling +2 位作者 WANG Jinge CHEN Shouan YANG Jie 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第6期1177-1185,共9页
A novel specific type of worm drive, so-called end face engagement worm gear(EFEWD), is originally presented to minimize or overcome the gear backlash. Different factors, including the three different types, contact... A novel specific type of worm drive, so-called end face engagement worm gear(EFEWD), is originally presented to minimize or overcome the gear backlash. Different factors, including the three different types, contact curves, tooth profile, lubrication angle and the induced normal curvature are taken into account to investigate the meshing characteristics and create the profile of a novel specific type of worm drive through mathematical models and theoretical analysis. The tooth of the worm wheel is very specific with the sine-shaped tooth which is located at the alveolus of the worm and the tooth profile of a worm is generated by the meshing movement of the worm wheel with the sine-shaped tooth, but just the end face of the worm(with three different typical meshing types) is adapted to meshing, and therefore an extraordinary manufacturing methods is used to generate the profile of the end face engagement worm. The research results indicates that the bearing contacts of the generated conjugate hourglass worm gear set are in line contacts, with certain advantages of no-backlash, high precision and high operating efficiency over other gears and gear systems besides the end face engagement worm gear drive may improve bearing contact, reduce the level of transmission errors and lessen the sensitivity to errors of alignment. Also, the end face engagement worm can be easily made with superior meshing and lubrication performance compared with the conventional techniques. In particular, the meshing and lubrication performance of the end face engagement worm gear by using the end face to meshing can be increased over 10% and 7%, respectively. This investigate is expect to provide a new insight on the design of the future no-backlash worm drive for industry. 展开更多
关键词 worm drive end face engagement worm gear meshing characteristics anti-backlash.
下载PDF
Optimal Design for an End Face Engagement Worm Gear with Multiple Worm-wheel Meshing 被引量:9
15
作者 DENG Xingqiao ZHU Weibing +2 位作者 CHEN Yonghong CHEN Shouan WANG Jinge 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2017年第1期144-151,共8页
To solve the problem for lacking a special mechanical transmission that could provide multiple outputs with high transmission efficiency and good lubrication in the modem industrial, a novel worm gear, named end face ... To solve the problem for lacking a special mechanical transmission that could provide multiple outputs with high transmission efficiency and good lubrication in the modem industrial, a novel worm gear, named end face engagement worm gear, with multiple worm-wheel meshing is proposed for the first time. The essential parameters for the worm gear are optimized to enhance lubrication and meshing properties. Moreover, analysis of variance(ANOVA) is applied to determine the optimum levels and to determine the influence of parameters. The ANOVA results show that the novel end face engagement worm gear with multiple worm wheels provides high lubrication(the lubrication angle is more than 89~) and meshing performance(the induce normal curvature is less than 0.0002 mm '). The interaction between center distance and roller slant distance most strongly influences the lubrication angle(contributed 51.6%), followed by the parameters of center distance(contributed 25.0%), roller slant distance(contributed 16.4%), tooth angle of gear, gear ratio, and roller radius. In addition, roller radius most strongly influences the induced normal curvature(contributed 39.4%), followed by roller slant distance(contributed 15.2%), tooth angle of the gear(contributed 9.0%), center distance, and gear ratio. The proposed worm gear helps to enrich the no-backlash high precision worm drive and the optimal design method can provide a useful reference on performance improvement of other worm gear. 展开更多
关键词 worm gear end face engagement worm optimization optimal design analysis of variance (ANOVA)
下载PDF
Modification Design Method for an Enveloping Hourglass Worm Gear with Consideration of Machining and Misalignment Errors 被引量:16
16
作者 DENG Xingqiao WANG Jinge HORSTEMEYER Mark F 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第5期948-956,共9页
The influences of machining and misalignment errors play a very critical role in the performance of the anti-backlash double-roller enveloping hourglass worm gear(ADEHWG).However,a corresponding efficient method for e... The influences of machining and misalignment errors play a very critical role in the performance of the anti-backlash double-roller enveloping hourglass worm gear(ADEHWG).However,a corresponding efficient method for eliminating or reducing these errors on the tooth profile of the ADEHWG is seldom reported.The gear engagement equation and tooth profile equation for considering six different errors that could arise from the machining and gear misalignment are derived from the theories of differential geometry and gear meshing.Also,the tooth contact analysis(TCA) is used to systematically investigate the influence of the machining and misalignment errors on the contact curves and the tooth profile by means of numerical analysis and three-dimensional solid modeling.The research results show that vertical angular misalignment of the worm wheel(Δβ) has the strongest influences while the tooth angle error(Δα) has the weakest influences on the contact curves and the tooth profile.A novel efficient approach is proposed and used to minimize the effect of the errors in manufacturing by changing the radius of the grinding wheel and the approaching point of contact.The results from the TCA and the experiment demonstrate that this tooth profile design modification method can indeed reduce the machining and misalignment errors.This modification design method is helpful in understanding the manufacturing technology of the ADEHWG. 展开更多
关键词 worm gears tooth contact analysis machining and misalignment errors tooth profile errors modification method
下载PDF
New Localities and Palaeoscolecid Worms from the Cambrian(Stage 4,Series 2)Guanshan Biota in Kunming,Yunnan,South China 被引量:5
17
作者 LIU Jianni HAN Jian +5 位作者 LI Jinshu WU Yichen PENG Jie QI Nan YANG Yiyao LI Juan 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2016年第6期1939-1945,共7页
The Guanshan Biota from the Cambrian Stage 4 Wulongqing Formation is a typical Burgess-shale type Lagerst?tte that had witnessed the Cambrian explosion. Here we report two new localities of the Guanshan Biota, which ... The Guanshan Biota from the Cambrian Stage 4 Wulongqing Formation is a typical Burgess-shale type Lagerst?tte that had witnessed the Cambrian explosion. Here we report two new localities of the Guanshan Biota, which is located at Baimei village, south of Kunming and Xinglong village, Wuding County, Yunnan Province respectively. Both localities produce soft-body fossils and several new taxa, e.g. a new species of palaeoscolecidans (Palaeoscolex xinglongensis sp. nov.) reported herein. The comparative study of the new species with similar form not only indicates that there is a diversification of palaeoscolecid species in Guanshan Biota, but also strengthens the ties between the older Chengjiang Biota and the younger Kaili Biota (and also the coeval Burgess Shale community). Three paleoecological features, including high diversity, little disparity and richness of palaeoscolecid worms, are summarized as a case study to represent the differences between Guanshan and Chengjiang Biota. 展开更多
关键词 Guanshan Biota Chengjiang Biota palaeoscolecid worms Cambrian Explosion China
下载PDF
Instant Messaging Worms Propagation Simulation and Countermeasures 被引量:2
18
作者 HU Huaping WEI Jianli 《Wuhan University Journal of Natural Sciences》 CAS 2007年第1期95-100,共6页
Instant messaging (IM) has become one of the most popular online communication tools among consumer and enterprise IM users. It provides instant message delivery, as well as convenient file transfer services. The in... Instant messaging (IM) has become one of the most popular online communication tools among consumer and enterprise IM users. It provides instant message delivery, as well as convenient file transfer services. The increasing popularity and functionalities of IM programs have made it increasingly attractive for attackers, especially for worm writers. IM contact list offers worm an easy way of finding potential victims so that the worm could achieve a surprising spreading speed. This paper first presents our experimental results of simulating IM worm propagation in the logical network defined by IM contact lists, which is reported to be a scale-free network. Then, the existing proposals for detecting and containing IM worm epidemics are discussed. At last, a new algorithm for this purpose is presented, which is based on the observation of the bi-directional nature of IM worm traffic, and its advantages and possible improvements in implementation are analyzed. The simulation results show the proposed algorithm is of significant effect on restricting IM worm propagation. 展开更多
关键词 instant messaging worms SIMULATION PROPAGATION worm detection and containment
下载PDF
Global dynamics of a novel multi-group model for computer worms 被引量:3
19
作者 巩永旺 宋玉蓉 蒋国平 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第4期56-62,共7页
In this paper, we study worm dynamics in computer networks composed of many autonomous systems. A novel multigroup SIQR (susceptible-infected-quarantined-removed) model is proposed for computer worms by explicitly c... In this paper, we study worm dynamics in computer networks composed of many autonomous systems. A novel multigroup SIQR (susceptible-infected-quarantined-removed) model is proposed for computer worms by explicitly considering anti-virus measures and the network infrastructure. Then, the basic reproduction number of worm R0 is derived and the global dynamics of the model are established. It is shown that if R0 is less than or equal to 1, the disease-free equilibrium is globally asymptotically stable and the worm dies out eventually, whereas, if R0 is greater than 1, one unique endemic equilibrium exists and it is globally asymptotically stable, thus the worm persists in the network. Finally, numerical simulations are given to illustrate the theoretical results. 展开更多
关键词 computer worm multi-group model Lyapunov function global dynamics
下载PDF
Mathematical Model and Geometrical Model of Double Pitch ZN-type Worm Gear Set Based on Generation Mechanism 被引量:2
20
作者 SHU Linsen CAO Huajun +2 位作者 LI Xianchong ZHANG Chenglong LI Yuxia 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2015年第3期549-555,共7页
The current researches on the tooth surface mathematical equations and the theory of gearing mainly pay attention to the ordinary type worm gear set(e.g., ZN, ZA, or ZK). The research of forming mechanism and three-... The current researches on the tooth surface mathematical equations and the theory of gearing mainly pay attention to the ordinary type worm gear set(e.g., ZN, ZA, or ZK). The research of forming mechanism and three-dimensional modeling method for the double pitch worm gear set is not enough. So there are some difficulties in mathematical model deducing and geometry modeling of double pitch ZN-type worm gear set based on generation mechanism. In order to establish the mathematical model and the precise geometric model of double pitch ZN-type worm gear set, the structural characteristics and generation mechanism of the double pitch ZN-type worm gear set are investigated. Mathematical model of the ZN-type worm gear set is derived based on its generation mechanism and the theory of gearing. According to the mathematical model of the worm gear set which has been developed, a geometry modeling method of the double pitch ZN-type worm and worm gear is presented. Furthermore, a geometrical precision calculate method is proposed to evaluate the geometrical quality of the double pitch worm gear set. As a result, the maximum error is less than 6′10–4 mm in magnitude, thus the model of the double pitch ZN-type worm gear set is available to meet the requirements of finite element analysis and engineering application. The derived mathematical model and the proposed geometrical modeling method are helpful to guiding the design, manufacture and contact analysis of the worm gear set. 展开更多
关键词 double pitch ZN-type worm gear set generation mechanism mathematical model geometrical model
下载PDF
上一页 1 2 165 下一页 到第
使用帮助 返回顶部