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基于压电晶片阵列的管中导波时反检测方法研究 被引量:3
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作者 周进节 郑阳 张吉堂 《机械工程学报》 EI CAS CSCD 北大核心 2013年第22期59-65,共7页
为提高超声导波技术对管中小缺陷的检测能力,提出一种采用窄带高压脉冲激发安装在管道外表面的压电晶片阵列实现管中导波时间反转检测的新方法。该方法采用窄带脉冲同时激励沿管道表面轴对称安装的压电晶片阵列,从各压电晶片接收到的反... 为提高超声导波技术对管中小缺陷的检测能力,提出一种采用窄带高压脉冲激发安装在管道外表面的压电晶片阵列实现管中导波时间反转检测的新方法。该方法采用窄带脉冲同时激励沿管道表面轴对称安装的压电晶片阵列,从各压电晶片接收到的反射回波中提取含L(n,2)模态的缺陷信息进行时间反转,并用获得的时反波再次激励阵列中对应压电晶片,整个阵列将同时接收到较单一L(n,2)模态信号。试验结果表明,该方法能较好地抑制导波的频散、多模态特性,提高缺陷回波信噪比,增加对小缺陷的检测能力。同时,时反前、后所检测到的管道端面和缺陷反射回波的导波模态几乎相同,可采用特定频率的L(0,2)模态群速度作为时反后缺陷波包的传播速度;且时反后的幅值最大的缺陷波包能重构窄带初始激励信号幅值最大的波包,可有效增加缺陷波包的辨识能力。 展开更多
关键词 管道 超声导波 压电晶片阵列 时反检测
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基于宽带脉冲激励的管道导波时反检测方法 被引量:1
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作者 周进节 贾浩东 郑阳 《机械设计与制造工程》 2020年第2期69-73,共5页
提出一种基于宽带信号激励的超声导波时间反转检测方法(时反检测方法),利用时间反转波包的自聚焦特性抑制管中导波的频散、多模态特性,以拓展激励信号的频率范围。该方法首先采用宽带脉冲信号作为初始激励信号,从接收信号中提取缺陷波... 提出一种基于宽带信号激励的超声导波时间反转检测方法(时反检测方法),利用时间反转波包的自聚焦特性抑制管中导波的频散、多模态特性,以拓展激励信号的频率范围。该方法首先采用宽带脉冲信号作为初始激励信号,从接收信号中提取缺陷波包信息进行时间反转(时反),并将时反后的信息作为激励信号,将再次检测到的缺陷波包作为时反检测结果。研究结果表明,利用时反检测方法得到的检测信号较之前的宽带检测信号,其缺陷波包的波形在时域变得更窄,反射系数得到有效提高,更容易区分出缺陷波包的时间位置。 展开更多
关键词 宽带脉冲 管道 超声导波 时反检测
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多基地空时码探测信号设计及时反相关检测技术 被引量:6
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作者 生雪莉 芦嘉 +2 位作者 凌青 徐江 董伟佳 《物理学报》 SCIE EI CAS CSCD 北大核心 2014年第5期194-202,共9页
为实现浅海复杂环境下的多基地声纳多源目标回波分辨,本文设计了一种适用于多入多出垂直阵信道环境下的空时码探测信号,并针对倾斜垂直阵的多途子信道差异问题,提出了信号的时反相关检测技术.空时码探测信号采用伪随机信号调制,具有良... 为实现浅海复杂环境下的多基地声纳多源目标回波分辨,本文设计了一种适用于多入多出垂直阵信道环境下的空时码探测信号,并针对倾斜垂直阵的多途子信道差异问题,提出了信号的时反相关检测技术.空时码探测信号采用伪随机信号调制,具有良好的正交性,能在抗子信道严重衰落的同时,分辨多源目标回波.垂直阵受水流冲击,呈倾斜状态时,其多途子信道不一致性会导致各子信道传递信号无法在接收端聚焦,使阵列增益受损,同时导致时延测量能力下降和信号判决错误率上升,为此本文设计了信道训练信号用以估计多途子信道环境,通过虚拟时间反转镜获得子信道不一致条件下的最佳匹配检测信号,实现对接收信号的时反相关检测.仿真结果表明,本文所设计的探测信号和检测方法,能够克服复杂的信道条件和多途子信道不一致性引起的检测问题,满足多基地声纳探测需求,实现多源目标回波分辨. 展开更多
关键词 空时码探测信号 时反相关检测 多途子信道差异 多源目标回波分辨
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Comparison of ligase detection reaction and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B 被引量:3
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作者 Xiao-Ling Wang Song-Gang Xie +3 位作者 Ling Zhang Wei-Xia Yang Xing Wang Hong-Zhi Jin 《World Journal of Gastroenterology》 SCIE CAS CSCD 2008年第1期120-124,共5页
AIM: To compare the ligase detection reaction (LDR) and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B infection.METHODS: Mixtures of plasmids and serum samples from 52 c... AIM: To compare the ligase detection reaction (LDR) and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B infection.METHODS: Mixtures of plasmids and serum samples from 52 chronic hepatitis B patients with low abundant lamivudine-resistant mutations were tested with LDR and real-time PCR. Time required and reagent cost for both assays were evaluated.RESULTS: Real-time PCR detected 100, 50, 10, 1 and 0.1% of YIDD plasmid, whereas LDR detected 100, 50, 10, 1, 0.1, and 0.01% of YIDD plasmid, in mixtures with YMDD plasmid of 106 copies/mL. Among the 52 clinical serum samples, completely concordant results were obtained for all samples by both assays, and 39 YIDD, 9 YVDD, and 4 YIDD/YVDD were detected. Cost and time required for LDR and real-time PCR are 60/80 CNY (8/10.7 US dollars) and 4.5/2.5 h, respectively.CONCLUSION: LDR and real-time PCR are both sensitive and inexpensive methods for monitoring low abundant YMDD mutants during lamivudine therapy in patients with chronic hepatitis B. LDR is more sensitive and less expensive, while real-time PCR is more rapid. 展开更多
关键词 YMDD mutants Hepatitis B virus Real-time PCR Ligase detection reaction
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Simultaneous Detection of Three Arboviruses Using a Triplex RT-PCR Enzyme Hybridization Assay
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作者 DanDong Shi—hongFu +3 位作者 Li-huaWang ZhiLv Tai-yuanLi Guo.dongLiang 《Virologica Sinica》 SCIE CAS CSCD 2012年第3期179-186,共8页
Arboviruses represent a serious problem to public health and agriculture worldwide. Fast, accurate identification of the viral agents of arbovirus-associated disease is essential for epidemiological surveillance and l... Arboviruses represent a serious problem to public health and agriculture worldwide. Fast, accurate identification of the viral agents of arbovirus-associated disease is essential for epidemiological surveillance and laboratory investigation. We developed a cost-effective, rapid, and highly sensitive one-step "triplex RT-PCR enzyme hybridization" assay for simultaneous detections of Japanese Encephallitis virus (JEV, Flaviviridae), Getah virus (GETV, Togaviridae), and Tahyna virus (TAHV, Bunyaviridae) using three pairs of primers to amplify three target sequences in one RT-PCR reaction. The analytical sensitivity of this assay was 1 PFU/mL for JEV, 10 PFU/mL for GETV, and 10 PFU/mL for TAHV. This assay is significantly more rapid and less expensive than the traditional serological detection and single RT-PCR reaction methods. When "triplex RT-PCR enzyme hybridization" was applied to 29 cerebrospinal fluid (CSF) samples that were JEV-positive by normal RT-PCR assay, all samples were strongly positive for JEV, but negative for GETV and TAHV, demonstrating a good sensitivity, specificity, and performance at CSF specimen detection. 展开更多
关键词 Japanese Encephalitis virus (JEV) Getah Virus (GETV) Tahyna Virus (TAHV) Multiplex RT-PCR Enzyme Hybridization
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Fair Data Collection Scheme in Wireless Sensor Networks
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作者 庞辽军 李慧贤 +2 位作者 裴庆棋 刘能宾 王育民 《China Communications》 SCIE CSCD 2013年第2期112-120,共9页
To solve the slow congestion detection and rate convergence problems in the existing rate control based fair data collection schemes, a new fair data collection scheme is proposed, which is named the improved scheme w... To solve the slow congestion detection and rate convergence problems in the existing rate control based fair data collection schemes, a new fair data collection scheme is proposed, which is named the improved scheme with fairness or ISWF for short. In ISWF, a quick congestion detection method, which combines the queue length with traffic changes of a node, is used to solve the slow congestion detection problem, and a new solution, which adjusts the rate of sending data of a node by monitoring the channel utilization rate, is used to solve the slow convergence problem. At the same time, the probability selection method is used in ISWF to achieve the fairness of channel bandwidth utilization. Experiment and simulation results show that ISWF can effectively reduce the reaction time in detecting congestion and shorten the rate convergence process. Compared with the existing tree-based fair data collection schemes, ISWF can achieve better fairness in data collection and reduce the transmission delay effectively, and at the same time, it can increase the average network throughput by 9.1% or more. 展开更多
关键词 wireless sensor networks con-gestion detection rate control probabilityselection FAIRNESS
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An Improved Water-filled Pulse Tube Method Using Time Domain Pulse Separation Method 被引量:1
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作者 Liang Sun Hong Hou 《Journal of Marine Science and Application》 2013年第1期122-125,共4页
Based on existing low-frequency water-filled impedance tube testing facilities, which is a part of the Low Frequency Facility of the Naval Undersea Warfare Center in Beijing, an improved water-filled pulse tube method... Based on existing low-frequency water-filled impedance tube testing facilities, which is a part of the Low Frequency Facility of the Naval Undersea Warfare Center in Beijing, an improved water-filled pulse tube method is presented in this short paper. This proposed study is significantly different from the conventional pulse tube method because of the capability for a single plane damped sine pulse wave to generate in the water-filled pulse tube with a regular waveform and short duration time of about 1ms. During the generation process of the pulse, an inverse filter principle was adopted to compensate the transducer response. The effect of the characteristics of tube termination can be eliminated through the generation process of the pulse. Reflection coefficient from a water/air interface was measured to verify the proposed method. When compared with the expected theoretical values, a relatively good agreement can be obtained in the low frequency range of 500-2 000 Hz. 展开更多
关键词 pulse tube damped sine pulse water-air surface water-filled pulse tube
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Label-free and real-time detection of antigen-antibody interactions by Oblique-incidence Reflectivity Difference(OIRD) method 被引量:4
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作者 HE LiPing SUN Yue +6 位作者 DAI Jun WANG JingYi LU HuiBin WANG ShuFang JIN KuiJuan ZHOU YueLiang YANG GuoZhen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第9期1585-1588,共4页
We label-free and real-time detected three interaction processes of antigen-antibodies,Human Immunoglobulin G(IgG),Rabbit IgG,and Mouse IgG as the targets,and Goat Anti-human IgG,Goat Anti-rabbit IgG,and Goat Anti-mou... We label-free and real-time detected three interaction processes of antigen-antibodies,Human Immunoglobulin G(IgG),Rabbit IgG,and Mouse IgG as the targets,and Goat Anti-human IgG,Goat Anti-rabbit IgG,and Goat Anti-mouse IgG as the probe,by the Oblique-incidence Reflectivity Difference(OIRD) method.The interaction dynamic curves of the OIRD signal,corresponding to the interaction processes of antigen-antibodies,are generated.The reaction times from beginning to equilibrium state are about 1800,900,and 1200 s for Human IgG,Rabbit IgG,and Mouse IgG,respectively.The experimental results demonstrate that the OIRD method not only can distinguish biomolecular interactions,but also can be used in real-time detection of interactions and dynamic processes of biomolecules. 展开更多
关键词 Oblique-incidence Reflectivity Difference (OIRD) label-free and real-time detection dynamic process of biomolecularinteraction
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Experimental study on applicability of using time-domain reflectometry to detect NAPLs contaminated sands 被引量:5
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作者 ZHAN LiangTong MU QingYi +1 位作者 CHEN YunMin CHEN RenPeng 《Science China(Technological Sciences)》 SCIE EI CAS 2013年第6期1534-1543,共10页
Underground contamination by non-aqueous phase liquids (NAPLs) becomes increasingly serious. Rapid and reliable detection of contaminated zone and degree is the first step to site remediation. In this paper, diesel an... Underground contamination by non-aqueous phase liquids (NAPLs) becomes increasingly serious. Rapid and reliable detection of contaminated zone and degree is the first step to site remediation. In this paper, diesel and fine sand are used as experiment materials to investigate the applicability of using time-domain reflectometry (TDR) to detect LNAPLs contamination. The major work includes: measurement of dielectric constant and electrical conductivity for the diesel-water-air-sand mixtures; measurement of reflection waveform and dielectric constant for specimens with a diesel contaminated layer being sandwiched in sand. The experimental results show the followings: A significant decrease in both dielectric constant and electrical conductivity is observed for the diesel-water-air-sand mixtures when diesel displaces the pore water, and the content of diesel can be calculated by the model; insignificant change in dielectric properties is measured when diesel only displaces the pore gas; when the diesel contaminated sand is sandwiched between two saturated sand layers, the interfaces of the diesel contaminated layer can be identified by analyzing the reflection waveform; for field application, TDR method is valid for the case that LNAPLs seep into saturated sand layer, and the applicability of TDR method in vadose zone depends on the initial saturation of the sand layer. The findings obtained in this paper provide a guidance for the use of TDR for the field investigation of NAPLs contaminated site. 展开更多
关键词 LNAPLS SAND time domain reflectometry dielectric constant electrical conductivity
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Label-free high-throughput and real-time detections of protein interactions by oblique-incidence reflectivity difference method 被引量:1
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作者 HE LiPing LIU Shuang +5 位作者 DAI JunBeijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Lü HuiBin JIN KuiJuan YANG GuoZhen 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2014年第4期615-618,共4页
Selected Mouse IgG of 1 mg/mL as target was fabricated on microarray for 500 sample dots.Label-free and real-time reaction dynamic processes were detected between the microarrays with Goat Anti-mouse IgG of 0.02 mg/mL... Selected Mouse IgG of 1 mg/mL as target was fabricated on microarray for 500 sample dots.Label-free and real-time reaction dynamic processes were detected between the microarrays with Goat Anti-mouse IgG of 0.02 mg/mL using the obliqueincidence reflectivity difference(OIRD)method.We obtained the reaction results and the reaction dynamic curves of 500 protein dots.In addition,we also used label-free detection of protein microarrays of 10080 sample dots,including BSA and different concentrations of Mouse IgG and Rabbit IgG,by OIRD.The obtained reaction results between the protein microarray with 1 mg/mL Goat Anti-mouse IgG and 1 mg/mL Goat Anti-rabbit IgG are reported herein.Experimental results show that OIRD can be not only label-free high-throughput detection method for biological microarrays but also label-free real-time detection in the interaction processes of biomolecules. 展开更多
关键词 oblique-incidence reflectivity difference(OIRD) LABEL-FREE REAL-TIME HIGH-THROUGHPUT
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