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Real-Time Wind Speed Analysis at Wind-Damaged Tower of a Transmission Line
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作者 Jiehua Ding Xiaoling Yang Yongsheng Zhao 《Journal of Electronic Research and Application》 2024年第6期58-65,共8页
Affected by the Super Typhoon“Mangkhut,”a total of five base towers of a transmission line in the mountainous area of China collapsed.In this paper,a mathematical model is established based on the Shuttle Radar Topo... Affected by the Super Typhoon“Mangkhut,”a total of five base towers of a transmission line in the mountainous area of China collapsed.In this paper,a mathematical model is established based on the Shuttle Radar Topography Mission(SRTM)data near the accident tower.The measured wind speed in the plain area under the mountain is used as the calculation boundary condition.The wind speed at the top of the mountain is calculated by using a numerical simulation method.The design wind speed and calculated wind speed at the tower site are compared,and the influence of wind speed on tower position in this wind disaster accident is analyzed. 展开更多
关键词 Power transmission line Wind disaster Design wind speed real-time wind speed Numerical simulation
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Modeling and Statistical Properties Research on Online Real-Time Information Transmission Network 被引量:2
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作者 Guangming Deng Zhen Jia 《Open Journal of Applied Sciences》 2014年第5期234-241,共8页
In this paper, the model of the online real-time information transmission network, such as wechat, micro-blog, and QQ network, is proposed and built, based on the connection properties between users of the online real... In this paper, the model of the online real-time information transmission network, such as wechat, micro-blog, and QQ network, is proposed and built, based on the connection properties between users of the online real-time information transmission network, and combined with the local world evolving characteristics in complex network, then the statistical topological properties of the network is obtained by numerical simulation. Furthermore, we simulated the process of information transmission on the network, according to the actual characteristics of the online real-time information transmission. Statistics show that the degree distribution presents the characteristics of scale free network, presenting power law distribution, while the average path length, the average clustering coefficient and the average size of the network also has a power-law relationship, moreover, the model parameters has no effect on power-law exponent. The spread of information on the network represents obvious fluctuation scaling, reflecting the characteristics that information transmission fluctuates over time. 展开更多
关键词 Network INFORMATION transmission real-time INFORMATION FLUCTUATION SCALING
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Real-time performance of periodic data transmission in EPA industrial Ethernet 被引量:2
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作者 刘宁 仲崇权 莫亚林 《Journal of Beijing Institute of Technology》 EI CAS 2012年第3期336-342,共7页
To evaluate and improve the real-time performance of Ethernet for plant automation(EPA) industrial Ethernet,the real-time performance of EPA periodic data transmission was theoretically and experimentally studied.By... To evaluate and improve the real-time performance of Ethernet for plant automation(EPA) industrial Ethernet,the real-time performance of EPA periodic data transmission was theoretically and experimentally studied.By analyzing information transmission regularity and EPA deterministic scheduling mechanism,periodic messages were categorized as different modes according to their entering-queue time.The scheduling characteristics and delivery time of each mode and their interacting relations were studied,during which the models of real-time performance of periodic information transmission in EPA system were established.On this basis,an experimental platform is developed to test the delivery time of periodic messages transmission in EPA system.According to the analysis and the experiment,the main factors that limit the real-time performance of EPA periodic data transmission and the improvement methods were proposed. 展开更多
关键词 Ethernet for plant automation(EPA) industrial Ethernet periodic data transmission real-time performance delivery time
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Transmission Considerations with QoS Support to Deliver Real-Time Distributed Speech Recognition Applications
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作者 Zhu Xiao-gang Zhu Hong-wen Rong Meng-tian 《Wuhan University Journal of Natural Sciences》 EI CAS 2002年第1期65-70,共6页
Distributed speech recognition (DSR) applications have certain QoS (Quality of service) requirements in terms of latency, packet loss rate, etc. To deliver quality guaranteed DSR application over wirelined or wireless... Distributed speech recognition (DSR) applications have certain QoS (Quality of service) requirements in terms of latency, packet loss rate, etc. To deliver quality guaranteed DSR application over wirelined or wireless links, some QoS mechanisms should be provided. We put forward a RTP/RSVP transmission scheme with DSR-specific payload and QoS parameters by modifying the present WAP protocol stack. The simulation result shows that this scheme will provide adequate network bandwidth to keep the real-time transport of DSR data over either wirelined or wireless channels. 展开更多
关键词 distributed speech recognition quality of service real-time transmission protocol resource reservation protocol wireless application protocol
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Development of 16-channels Compact EEG System Using Real-time High-speed Wireless Transmission
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作者 B. R. Myung S. K. Yoo 《Engineering(科研)》 2013年第5期93-97,共5页
For the convenience of people with disability and for normal people, a demand for intelligent interfaces is ever increasing and therefore related studies are actively being conducted. Recently a study is being conduct... For the convenience of people with disability and for normal people, a demand for intelligent interfaces is ever increasing and therefore related studies are actively being conducted. Recently a study is being conducted to develop an interface through face expression, movement of the body and eye movements, and further more active attempts to use electrical signals(brainwave, electrocardiogram, electromyogram) measured from the human body is also actively being progressed. In addition, the development and the usage of mobile devices and smart devices are promoting these research activities even more. The brainwave is measured by electrical activities between nerve cells in the cerebral cortex using scalp electrodes. The brainwave is mainly used for diagnosis and treatment of diseases such as epilepsy, encephalitis, brain tumors and brain damage. As a result, the brainwave measurement methods and analytical methods were developed. Interface using the brainwave will not go through language or body behavior which is the result of the information processed by the brain but will pass directly to the system providing a brain-computer interface (BCI). This is possible because a variety of the brainwave appears depending on the human’s physical and mental state. Using the brainwave with the intelligent brain-computer interface or combining it with mobile devices and smart devices, regardless of space constraints, the brainwave measurement should be possible.[4,7] In this study, in order to measure the brainwave without spatial constraint, 16 channel compact brainwave measurements system using a high-speed wireless communications were designed. It was designed with a 16 channel to classify the various brainwave patterns that appear and for estimating the location of the nerve cells that triggered the brainwave. And in order to transmit the brainwave data within the channel without loss, a high-speed wireless communication must be possible that can enable a high-speed wireless transmission more sufficient than the Bluetooth, therefore, 802.11 compliant Wi-Fi communication methods were used to transfer the data to the PC. In addition, by using an analog front-end IC having a single-chip configuration with real-time digital filters, the miniaturization of the system was implemented and in order to verify the system Eye-blocking was used to observe the changes in the EEG signal. 展开更多
关键词 ELECTROENCEPHALOGRAPHY HIGH-SPEED WIRELESS transmission real-time
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Development of TaqMan-based Real-time PCR Assay for Detecting Transmissible Gastroenteritis Virus and Its Application in Vaccine Evaluation 被引量:2
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作者 俞正玉 徐向伟 +8 位作者 孙冰 何孔旺 郭容利 杜露平 温立斌 张雪寒 茅爱华 倪艳秀 李彬 《Agricultural Science & Technology》 CAS 2014年第9期1487-1490,共4页
[Objective] This study aimed to establish a TaqMan-based real-time PCR assay for detecting transmissible gastroenteritis virus (TGEV). [Method] Primers and a probe were designed according to the conserved sequence o... [Objective] This study aimed to establish a TaqMan-based real-time PCR assay for detecting transmissible gastroenteritis virus (TGEV). [Method] Primers and a probe were designed according to the conserved sequence of N gene in TGEV genome. After gradient dilution, the recombinant plasmid harboring the N gene was used as a standard for real-time PCR assay to establish the standard curve. [Re- sult] The results showed that the established real-time PCR assay exhibited a good linear relationship within the range of 102-10^10 copies/ul; the correlation coefficient was above 0.99 and the amplification efficiency ranged from 90% to 110%. The de- tection limit of real-time PCR assay for TGEV was 10 copies/μl, suggesting a high sensitivity; there was no cross reaction with other porcine viruses, indicating a good specificity; coefficients of variation within and among batches were lower than 3%, suggesting a good repeatability. The established real-time PCR method could be ap- plied in quantitative analysis and evaluation of the immune efficacy of TGEV vac- cines and detection of TGEV in clinical samples. [Conclusion] The TaqMan-based real-time PCR assay established in this study is highly sensitive and specific, which can provide technical means for the epidemiological survey of TGEV, development of TGEV vaccines and investigation of the pathogenesis of TGE. 展开更多
关键词 transmissible gastroenteritis virus (TGEV) TaqMan-based real-time PCR: Detection
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Reflection and transmission of bottom simulating reflectors in gas hydrate-bearing sediments: Two-phase media models 被引量:2
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作者 麻纪强 耿建华 《Applied Geophysics》 SCIE CSCD 2008年第1期57-66,共10页
The bottom simulating reflector (BSR) in gas hydrate-bearing sediments is a physical interface which is composed of solid, gas, and liquid and is influenced by temperature and pressure. Deep sea floor sediment is a ... The bottom simulating reflector (BSR) in gas hydrate-bearing sediments is a physical interface which is composed of solid, gas, and liquid and is influenced by temperature and pressure. Deep sea floor sediment is a porous, unconsolidated, fluid saturated media. Therefore, the reflection and transmission coefficients computed by the Zoeppritz equation based on elastic media do not match reality. In this paper, a two-phase media model is applied to study the reflection and transmission at the bottom simulating reflector in order to find an accurate wave propagation energy distribution and the relationship between reflection and transmission and fluid saturation on the BSR. The numerical experiments show that the type I compressional (fast) and shear waves are not sensitive to frequency variation and the velocities change slowly over the whole frequency range. However, type II compressional (slow) waves are more sensitive to frequency variation and the velocities change over a large range. We find that reflection and transmission coefficients change with the amount of hydrate and free gas. Frequency, pore fluid saturation, and incident angle have different impacts on the reflection and transmission coefficients. We can use these characteristics to estimate gas hydrate saturation or detect lithological variations in the gas hydrate-bearing sediments. 展开更多
关键词 Gas hydrate BSR two-phase media reflection coefficient transmission coefficient.
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Reflection and transmission of Laguerre Gaussian beam from uniaxial anisotropic multilayered media 被引量:2
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作者 李海英 吴振森 +2 位作者 尚庆超 白璐 李正军 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第3期330-335,共6页
Based on angular spectrum expansion and 4 × 4 matrix theory, the reflection and transmission characteristics of a Laguerre Gaussian (LG) beam from uniaxial anisotropic multilayered media are studied. The reflec... Based on angular spectrum expansion and 4 × 4 matrix theory, the reflection and transmission characteristics of a Laguerre Gaussian (LG) beam from uniaxial anisotropic multilayered media are studied. The reflected and transmitted beam fields of an LG beam are derived. In the case where the principal coordinates of the uniaxial anisotropic media coincide with the global coordinates, the reflected and transmitted beam intensities from a uniaxial anisotropic slab and three-layered media are numerically simulated. It is shown that the reflected intensity components of the incident beam, especially the TM polarized incident beam, are smaller than the transmitted intensity components. The distortion of the reflected intensity component is more evident than that of the transmitted intensity component. The distortion of intensity distribution is greatly affected by the dielectric tensor and the thickness of anisotropic media. We finally extend the application of the method to general anisotropic multilayered media. 展开更多
关键词 Laguerre Gaussian beam reflection and transmission uniaxial anisotropic multilayered media
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A novel on-line electrochemical transmission infrared spectroscopy to study the current efficiency of carbonates for ethanol oxidation reactions in alkaline media
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作者 Wei Peng Li Xiao +1 位作者 Juntao Lu Lin Zhuang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2019年第11期78-83,共6页
Research on the reaction mechanism of ethanol oxidation reaction(EOR) is important for the development of highly active EOR electro-catalysts. One of the main difficulties in the EOR study is the quantitative analysis... Research on the reaction mechanism of ethanol oxidation reaction(EOR) is important for the development of highly active EOR electro-catalysts. One of the main difficulties in the EOR study is the quantitative analysis of the non-volatile products. Conventional on-line electrochemical flowing transmission infrared spectroscopy(ETIRS) can only collect a part of the carbonate products of EOR in alkaline media, making the further quantitative study impossible. Herein, a new ETIRS system has been designed and prepared by employing a cation-exchange membrane(Nafion) in the sampling hood. The using of the Nafion membrane can prevent the anions crossing over by confining the generated carbonates in the sampling hood without diffusing into the bulk electrolyte. Therefore, the collection efficiency of the carbonate products as well as the test accuracy of the carbonate current efficiency has been significantly improved. The result of CO stripping reaction shows that ca. 100% of the carbonate product is able to be collected in alkaline media by this new system. The influence of the experimental temperature to the carbonate current efficiency has been further studied on Pt/C toward EOR in alkaline media. 展开更多
关键词 ETHANOL oxidation reaction transmission infrared spectroscopy PLATINUM ALKALINE media
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PROXY-BASED PATCHING STREAM TRANSMISSION STRATEGY IN MOBILE STREAMING MEDIA SYSTEM
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作者 Liao Jianxin Lei Zhengxiong Ma Xutao Zhu Xiaomin 《Journal of Electronics(China)》 2006年第4期515-519,共5页
A mobile transmission strategy, PMPatching (Proxy-based Mobile Patching) transmission strat-egy is proposed, it applies to the proxy-based mobile streaming media system in Wideband Code Division Multiple Access (WCDMA... A mobile transmission strategy, PMPatching (Proxy-based Mobile Patching) transmission strat-egy is proposed, it applies to the proxy-based mobile streaming media system in Wideband Code Division Multiple Access (WCDMA) network. Performance of the whole system can be improved by using patching stream to transmit anterior part of the suffix that had been played back, and by batching all the demands for the suffix arrived in prefix period and patching stream transmission threshold period. Experimental results show that this strategy can efficiently reduce average network transmission cost and number of channels consumed in central streaming media server. 展开更多
关键词 Mobile streaming media system Proxy-based Mobile Patching (PMPatching) transmission strategy Patching stream Batching
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Design and implementation of multi-hop video transmission experiment system in VANET
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作者 默罕莫德.默森 许凯凯 +1 位作者 刘诚毅 沈连丰 《Journal of Southeast University(English Edition)》 EI CAS 2014年第4期403-410,共8页
Abts ract A wireless mutl i-hop videot ransmission experiment system is designed and implemented for vehiculra ad-hoc networks VANET and the rt ansm ission control protocol and routing protocol are proposed. This syst... Abts ract A wireless mutl i-hop videot ransmission experiment system is designed and implemented for vehiculra ad-hoc networks VANET and the rt ansm ission control protocol and routing protocol are proposed. This system in tegrates the embedded Linux system witha n ARM kernel and oc ns ists of a S3C6410 main control module a wirel ss local arean etwork WLAN card a LCD screne and so on.In the scenario of a wireless multi-hop video transmission both the H.264 and JPEG are used and their performances such as the compression rate delay and frame loss rate are analyzed in theory andc ompared in the experiment.The system is tested in the real indoor and outdoor environment.The results show that the scheme of the multi-hop video transmission experiment system can be applicable for VANET and multiple scenes and the transmission control protocol and routing protocol proposed can achieve real-time transmission and meet multi-hop requirements. 展开更多
关键词 vehicular ad-hoc networks VANET embedded Linux multi-hop video transmission real-time property
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Wave transmission through laminated composite double-walled cylindrical shell lined with porous materials 被引量:2
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作者 K.DANESHJOU H.RAMEZANI R.TALEBITOOTI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2011年第6期701-718,共18页
A study on free harmonic wave propagation in a double-walled cylindrical shell, whose walls sandwich a layer of porous materials, is presented within the framework of the classic theory for laminated composite shells.... A study on free harmonic wave propagation in a double-walled cylindrical shell, whose walls sandwich a layer of porous materials, is presented within the framework of the classic theory for laminated composite shells. One of the most effective components of the wave propagation through the porous core is estimated with the aid of a flat panel with the same geometrical properties. By considering the effective wave component, the porous layer is modeled as a fluid with equivalent properties. Thus, the model is simplified as a double-walled cylindrical shell trapping the fluid media. Finally, the transmission loss (TL) of the structure is estimated in a broadband frequency, and then the results are compared. 展开更多
关键词 transmission loss porous media cylindrical laminated composite shell
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A real-time AI-assisted seismic monitoring system based on new nodal stations with 4G telemetry and its application in the Yangbi M_(S) 6.4 aftershock monitoring in southwest China 被引量:2
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作者 Junlun Li Huajian Yao +10 位作者 Baoshan Wang Yang Yang Xin Hu Lishu Zhang Beng Ye Jun Yang Xiaobin Li Feng Liu Guoyi Chen Chang Guo Wen Yang 《Earthquake Research Advances》 CSCD 2022年第2期3-10,共8页
A rapidly deployable dense seismic monitoring system which is capable of transmitting acquired data in real time and analyzing data automatically is crucial in seismic hazard mitigation after a major earthquake.Howeve... A rapidly deployable dense seismic monitoring system which is capable of transmitting acquired data in real time and analyzing data automatically is crucial in seismic hazard mitigation after a major earthquake.However,it is rather difficult for current seismic nodal stations to transmit data in real time for an extended period of time,and it usually takes a great amount of time to process the acquired data manually.To monitor earthquakes in real time flexibly,we develop a mobile integrated seismic monitoring system consisting of newly developed nodal units with 4G telemetry and a real-time AI-assisted automatic data processing workflow.The integrated system is convenient for deployment and has been successfully applied in monitoring the aftershocks of the Yangbi M_(S) 6.4 earthquake occurred on May 21,2021 in Yangbi County,Dali,Yunnan in southwest China.The acquired seismic data are transmitted almost in real time through the 4G cellular network,and then processed automat-ically for event detection,positioning,magnitude calculation and source mechanism inversion.From tens of seconds to a couple of minutes at most,the final seismic attributes can be presented remotely to the end users through the integrated system.From May 27 to June 17,the real-time system has detected and located 7905 aftershocks in the Yangbi area before the internal batteries exhausted,far more than the catalog provided by China Earthquake Networks Center using the regional permanent stations.The initial application of this inte-grated real-time monitoring system is promising,and we anticipate the advent of a new era for Real-time Intelligent Array Seismology(RIAS),for better monitoring and understanding the subsurface dynamic pro-cesses caused by Earth's internal forces as well as anthropogenic activities. 展开更多
关键词 Seismic dense array 4G data transmission real-time earthquake monitoring Machine-learning assisted processing real-time intelligent array seismology
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Priority-Based Real-Time Stream Coding over Multi-Channel with Packet Erasures
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作者 Yunkai Wei Qianyu Liu +1 位作者 Zhoucha Hu Yuming Mao 《China Communications》 SCIE CSCD 2017年第1期72-85,共14页
Multi-channel can be used to provide higher transmission ability to the bandwidth-intensive and delay-sensitive real-time streams. However, traditional channel capacity theories and coding schemes are seldom designed ... Multi-channel can be used to provide higher transmission ability to the bandwidth-intensive and delay-sensitive real-time streams. However, traditional channel capacity theories and coding schemes are seldom designed for the real-time streams with strict delay constraint, especially in multi-channel context. This paper considers a real-time stream system, where real-time messages with different importance should be transmitted through several packet erasure channels, and be decoded by the receiver within a fixed delay. Based on window erasure channels and i.i.d.(identically and independently distributed) erasure channels, we derive the Multi-channel Real-time Stream Transmission(MRST) capacity models for Symmetric Real-time(SR) streams and Asymmetric Real-time(AR) streams respectively. Moreover, for window erasures, a Maximum Equilibrium Intra-session Code(MEIC) is presented for SR and AR streams, and is shown able to asymptotically achieve the theoretical MRST capacity. For i.i.d. erasures, we propose an Adaptive Maximum Equilibrium Intra-session Code(AMEIC), and then prove AMEIC can closely approach the MRST transmission capacity. Finally, the performances of the proposed codes are verified by simulations. 展开更多
关键词 real-time stream MULTI-CHANNEL channel coding erasure model transmission capacity
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Phase-shift interferometry measured transmission matrix of turbid medium: Three-step phase-shifting interference better than four-step one
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作者 Xi-Cheng Zhang Zuo-Gang Yang +3 位作者 Long-Jie Fang Jing-Lei Du Zhi-You Zhang Fu-Hua Gao 《Chinese Physics B》 SCIE EI CAS CSCD 2021年第10期297-305,共9页
Transmission matrix(TM)is an important tool for controlling light focusing,imaging,and communication through turbid media.It can be measured by 3-step(TM3)or 4-step(TM4)phase-shifting interference,but the similarities... Transmission matrix(TM)is an important tool for controlling light focusing,imaging,and communication through turbid media.It can be measured by 3-step(TM3)or 4-step(TM4)phase-shifting interference,but the similarities and differences of the transmission matrices obtained by the two methods are rarely reported.Therefore,we make a quantitative comparison of the peak light intensity,signal-to-noise ratio,and average background of 24×24=576 focal points between paired samples(TM3-TM4)through the Wilcoxon rank sum test,and discuss the singular value of the transmission matrix and the focal peak.The comparative results of peak light intensity and signal-to-noise ratio show that there is a significant difference between the 3-step phase shift and the 4-step phase shift transmission matrixes.The focusing effect of the former is significantly better than that of the latter;interest concentrates on the focal intensity and singular value.The reciprocal of the singular value is proportional to the squared intensity,which is in accordance with singular value theory.The results of comparison of peak light intensity and signal-to-noise ratio strongly suggest that 3-step phase shift should be selected and used in applying the phase shift method to the measurement of the transmission matrix;and the singular value is of great significance in quantifying the focusing,imaging,and communication quality of the transmission matrix. 展开更多
关键词 scattering media phase modulation transmission matrix focal point
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A Method of Insulator’s NSDD Measurement and Its Device Based on Laser Transmission Principle
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作者 Yang Liu Song Gao +1 位作者 Jie Chen Yanlong Lu 《Journal of Power and Energy Engineering》 2014年第4期518-524,共7页
Accuracy measurement of the Non-soluble Deposit Density (NSDD) on the insulator surface is very important for the transmission line anti-pollution flashover works. A method to measure the NSDD on double sheds porcelai... Accuracy measurement of the Non-soluble Deposit Density (NSDD) on the insulator surface is very important for the transmission line anti-pollution flashover works. A method to measure the NSDD on double sheds porcelain insulator surface based on laser transmission principle is proposed in this paper. Laser unit and luminous intensity sensor are installed between the up and down surface of the double sheds porcelain insulators, two glass tablets are put between the double sheds. The contamination on the glass tablets will influence the luminous intensity that reaches the intensity sensor. The luminous signal is changed to electrical signal, and the insulator’s NSDD could be obtained based on the difference of luminous intensity. The device can be used in online monitoring of the insulator's NSDD condition on the insulator surface. 展开更多
关键词 LASER transmission NSDD LUMINOUS INTENSITY real-time MEASUREMENT DEVICE
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Preliminary Remarks on Transmission and Communication in Ancient Greece: A Case Study in Mediology
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作者 lwona Wiezel 《Sociology Study》 2012年第10期797-804,共8页
The scope of this paper lies primarily on the recognition of what Debray called transmission and communication, however, in this article exclusively with regard to the Ancient Greek literature and culture. Transmissio... The scope of this paper lies primarily on the recognition of what Debray called transmission and communication, however, in this article exclusively with regard to the Ancient Greek literature and culture. Transmission understood as the process in which "agencies and human actors transmit the ideas in historical and diachronic order" and communication implying the "synchronic interchange by linguistic impact between senders and receivers" are presented as two paths in which cultural messages are introduced and transmitted by means of "literary production". Early Greek literature, which was based on the oral performance and mirrored the language in its prototypical form, seemed to be the main source of information for the reconstruction of the two above processes. In the proposed model, the new understanding of the media introduced by Debray plays the most important role, because in the theory of "cultural transmission", the medium can be not only "a symbolic process, a social code, a material device" but also a human being. Therefore, on the basis of this theory, mediology can be described as the way of 4M: message, medium, milieu, and mediation. 展开更多
关键词 transmission COMMUNICATION Ancient Greek literature and culture mediology media
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Reflection and transmission coefficient approximation at weak-contrast interfaces for strong VTI media
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作者 Xingyao YIN Yaming YANG +1 位作者 Kai LIANG Kun LI 《Science China Earth Sciences》 SCIE EI CAS CSCD 2024年第12期3914-3938,共25页
Reflection and transmission(R/T)responses characterize the propagation and energy distribution of incident and reflected waves on both sides of an interface which is crucial for imaging,amplitude variation with offset... Reflection and transmission(R/T)responses characterize the propagation and energy distribution of incident and reflected waves on both sides of an interface which is crucial for imaging,amplitude variation with offset(AVO),and seismic inversion techniques.Subsurface media are typically characterized by anisotropy which can have a significant impact on the R/T response,even at small incident angles.Currently,anisotropic media problems including reflection,transmission,and inversion are generally discussed under a weak anisotropy assumption.However,this assumption is no longer valid in cases of large angles where anisotropy enhancement exacerbates the error of the conventional R/T coefficient approximation.An R/T coefficient approximation method for strong VTI media was proposed based on the assumption of weak-contrast of the media.In contrast to the conventional approach,which simplifies the phase velocity and polarization in an anisotropic background,the phase velocity and polarization at the weak-contrast interface of the elasticity and anisotropy parameters were approximated using a combination of the anisotropic background and perturbation terms.Specifically,a first-order approximation of the R/T coefficients for the VTI media characterized by elastic and anisotropic parameters was derived using Cramer's law to invert the anisotropic background matrix,avoiding the assumption of weak anisotropy.Subsequently,the exact solution of the Zoeppritz equations was used to correct the isotropic part,improving the accuracy of the R/T coefficients at interfaces with high-velocity contrast.Modeling tests on four classes of typical interfaces showed that the derived equations can be degraded to the Aki approximation in isotropic media,while exhibiting high accuracy in strong VTI media.Uncertainty analyses showed that a linear approximation that facilitates seismic inversion can be obtained by taking the S-to P-velocity ratio and anisotropy parameters in the coefficient terms a priori. 展开更多
关键词 Reflection and transmission coefficients Strong anisotropy VTI media Weak-contrast PHASE-VELOCITY Polarization
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Flexible piezoelectret film sensor for noncontact mechanical signal capture by multiple transmission media
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作者 Xingchen Ma Qianqian Hu +7 位作者 Lian Zhou Xinhao Xiang Yi Qin Ke Zhang Pengfei He Ying Dai Wenxin Niu Xiaoqing Zhang 《Nano Research》 SCIE EI CSCD 2024年第8期7643-7657,共15页
Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring ... Mechanical signal capture without physical contact has emerged as a highly promising research field and attracted tremendous attention due to its prosperous applications in household medical care,lifestyle monitoring and remote operation,offering users high level of safety,convenience and comfort.Moreover,noncontact sensing is ideal to maximize the immersive user experience in the human–machine interaction(HMI),eliminating interference to human activities and mechanical fatigue to the sensor,simultaneously.Herein,we report a self-powered flexible sensor integrated with irradiation cross-linked polypropylene(IXPP)piezoelectret film for noncontact sensing,featuring multi-functions to detect mechanical signals transmitted through solid,liquid and gaseous media and would facilitate their versatile practical applications.The folded-structure configuration of the sensor facilitates the improvement of the noncontact sensing sensitivity.For solid media,such as the rectangular wooden stick used in this study,the sensor can detect mechanical stimulus exerted at a distance of 100 cm.A system detection sensitivity up to 57 pC/kPa with a low detection limit of 0.6 kPa is achieved at a noncontact distance of 10 cm.Even when partly or completely immersed in water,the sensor effectively traces movement signals of human bodies underwater,demonstrating great advantages for non-inductive aquatic fitness training monitoring.Furthermore,due to the low acoustic impedance of piezoelectret film,speech recognition through gaseous medium is also achieved.We further introduce application demonstrations of the developed film sensors to monitor exercise postures and physiological signals without direct contact between human body and the sensor,displaying great potential to be incorporated into future smart electronics.This study commendably expands the application scope of piezoelectret materials,which will have profound implications for exploring novel intelligent human–machine interactions. 展开更多
关键词 noncontact sensing piezoelectret multiple transmission media mechanical signal capture
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A new numerical technique for simulating the coupled seismic and electromagnetic waves in layered porous media 被引量:13
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作者 Hengxin Ren Qinghua Huang Xiaofei Chen 《Earthquake Science》 CSCD 2010年第2期167-176,共10页
Chen's technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen (LAC) generalized reflection and transmis... Chen's technique of computing synthetic seismograms, which decomposes every vector with a set of basis of orthogonality and completeness before applying the Luco-Apsel-Chen (LAC) generalized reflection and transmission coefficients method, is confirmed to be efficient in dealing with elastic waves in multi-layered media and accurate in any frequency range. In this article, we extend Chen's technique to the computation of coupled seismic and electromagnetic (EM) waves in layered porous media. Expanding the involved mechanical and electromagnetic fields by a set of scalar and vector wave-function basis, we obtain the fundamental equations which are subsequently solved by using a recently developed version of the LAC generalized reflection and transmission coefficients method. Our approach and corresponding program is validated by reciprocity tests. We also show a numerical example of a two-layer model with an explosion source. The P-to-EM conversion waves radiated from the interface may have potential application. 展开更多
关键词 synthetic seismogram porous media electrokinetic effect generalized reflection and transmission coefficients
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