检索结果-南通市图书馆

Plasma Science and Technology 2014年第9期16卷 861-866页

作者：李峰高超郑博睿王玉帅 National Key Laboratory of Science and Technology on Aerodynamic Design and Research Northwestern Polytechnical University

Using a plexiglas plate model, the performance of peristaltic flow acceleration in- duced by multiple DBD （dielectric barrier discharge） plasma actuators was studied based on PIV （particle image velocimetry）. The asynchronous and the duty cycle pulsed actuation modes were proposed and tested. The velocity fields induced by multiple DBD plasma actuators with different phase angles and duty cycle ratios were acquired and the momentum transfer characteristics of the flow field were discussed. Consequently, the mechanism of the peristalsis-acceleration multi- ple DBD plasma actuation was analyzed. The results show that the peristaltic flow acceleration effect of multiple plasma actuators occurs mainly in paraelectric direction, and the mechanism of peristaltic flow acceleration is ejection pushing effect rather than injection pumping effect. The asynchronous and the duty cycle pulsed actuation modes can, with energy consumption increase of merely 10%, achieve 65% and 42% increase of downstream velocity, and thus are promising in velocity improvement and energy saving.

关键词： peristaltic acceleration DBD plasma asynchronous duty cycle

An Adjust duty cycle Method for Optimized Congestion Avoidance and Reducing Delay for WSNs

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2020年第11期65卷 1605-1624页

作者： Ting Xu Ming Zhao Xin Yao Kun He School of Computer Science and Engineering Central South UniversityChangsha410075China Apple Inc. CupertinoCalifornia95014USA

With the expansion of the application range and network scale of wireless sensor networks in recent years,WSNs often generate data surges and delay queues during the transmission process,causing network paralysis,even resulting in local or global *** this paper,a dynamically Adjusted duty cycle for Optimized Congestion based on a real-time Queue Length(ADCOC)scheme is *** order to improve the resource utilization rate of network nodes,we carried out optimization analysis based on the theory and applied it to the adjustment of the node’s duty cycle *** this strategy to ensure that the network lifetime remains the same,can minimize system delay and maximize energy ***,the problems of the existing RED algorithm are *** introduce the improved SIG-RED algorithm into the ADCOC *** the data traffic changes,the RED protocol cannot automatically adjust the duty cycle.A scheduler is added to the buffer area manager,referring to a weighted index of network congestion,which can quickly determine the status of network *** value of the weighting coefficient W is adjusted by the Bayesian *** scheduler preferably transmits severely urgent data,alleviating the memory *** we combined improved data fusion technology and information gain methods to adjust the duty cycle *** simulating the algorithm,it shows that it has faster convergence speed and smaller queue ***,we combine the adjusted congestion weight and the duty cycle growth value to adjust the data processing rate capability in the real-time network by dynamically adjusting it to adapt to bursts of data ***,the frequency of congestion is reduced to ensure that the system has higher processing efficiency and good adaptability.

关键词： duty cycle congestion data fusion network lifetime delay weight data processing capability

Design of the pulse duty cycle of the pseudolite signal in local area augmentation systems

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2011年第6期54卷 1004-1008页

作者： LI ChunXia CHEN JinPing CHU HengLin Beijing Global Information Application and Development Center Beijing 100094China

The short-pulse TDMA signal is an excellent solution to the near-far problem in the pseudolite augmentation systems,and the pulse duty cycle is an important element in the *** paper aims at designing the duty cycle of the pseudolite pulse signals with a theoretical *** first,the scope of the duty cycle is derived theoretically with the object of ensuring the reception of both the pseudolite signals and the satellite signals,and the expression for the theoretical upper limit is *** based on the proposed expression,the duty cycles of Galileo pseudolite pulse signals are *** theoretical upper limit can guide the design of the short-pulse TDMA pseudolite signals.

关键词： pseudolite short-pulse TDMA duty cycle

A novel slot scheduling technique for duty-cycle based data transmission for wireless sensor network

在线全文

学校读者我要写书评

暂无评论

Digital Communications and Networks 2022年第3期8卷 351-358页

作者： Yogesh Tripathi Arun Prakash Rajeev Tripathi Department of Electronics and Communication Engineering Motilal Nehru National Institute of Technology AllahabadPrayagraj211004India

The duty cycling process involves turning a radio into an active and dormant state for conserving energy. It is a promising approach for designing routing protocols for a resource-constrained Wireless Sensor Networks (WSNs). In the duty cycle-based WSNs, the network lifetime is improved and the network transmission is increased as compared to conventional routing protocols. In this study, the active period of the duty cycle is divided into slots that can minimize the idle listening problem. The slot scheduling technique helps determine the most efficient node that uses the active period. The proposed routing protocol uses the opportunistic concept to minimize the sender waiting problem. Therefore, the forwarder set will be selected according to the node's residual active time and energy. Further, the optimum routing path is selected to achieve the minimum forwarding delay from the source to the destination. Simulation analysis reveals that the proposed routing scheme outperforms existing schemes in terms of the average transmission delay, energy consumption, and network throughput.

关键词： duty cycle Energy model Wireless sensor network Slot scheduling technique

Flow Control over a Conical Forebody by duty-cycle Actuations

在线全文

学校读者我要写书评

暂无评论

Plasma Science and Technology 2012年第1期14卷 58-63页

作者： ZHENG Borui GAO Chao LI Yibin LIU Feng LUO Shijun Northwestern Polytechnical University Xi’an 710072China University of California IrvineCA 92697-3975USA

duty-cycle modulation alternately blowing from two opposite-facing plasma actu- ators on the leeward surface near the apex of a cone with a 10° semi-apex angle is adopted to control mean lateral force and moment, and the flow control mechanisms are presented. Pressure distributions over the forebody of the cone are measured by steady pressure tappings. The experiments are performed in a 3.0×1.6 m open-circuit wind tunnel at a wind speed of 20 m/s, a 45° angle of attack and a Reynolds number of 2×10^5, based on the diameter of the base of the cone. Almost linearly proportional control of the lateral forces and moments over a slender conical forebody at a high angle of attack has been demonstrated by employing a pair of single dielectric barrier discharge plasma actuators near the apex of the cone, combined with a duty-cycle tech- nique. The pressure distribution measurements indicate that the hi-stable vortex pattern appears to be shifted in the opposite direction when the port or starboard actuator is activated, while the other is kept off during the test. It is shown that the reduced pulse-repetition frequency based on the local diameter at the plasma actuator equal to one yields the highest effectiveness among the cases considered.

关键词： conical forebody plasma actuator flow control duty cycle

Adjusting Sink Location to Reduce End-to-End Delay in Low-duty-cycle Wireless Sensor Networks

在线全文

学校读者我要写书评

暂无评论

Journal of Electronic Science and Technology 2015年第1期13卷 20-26页

作者： Yu-Yuan Lin Kuo-Feng Ssu Hau-Yu Chiang Institute of Computer and Communication Engineering National Cheng Kung University Department of Electrical Engineering National Cheng Kung University Data Systems Consulting Co. Ltd

Low-duty-cycle mechanisms can reduce the energy consumption significantly in wireless sensor networks（WSNs）. Sensors stay dormant most of the time to save their energy and wake up based on their needs. However, such a technique, while prolonging the network lifetime, sets excessive challenges for reducing the end-to-end（E2E） delay within the network. In this paper, the centralized cluster-based location finding（CCLF） algorithm is proposed to reduce the high latency in low-duty-cycle WSNs by finding a suitable position for the sink. The algorithm is mainly composed of three steps： a） the cluster construction, b） the fast look-up table（FLU-table） construction, and c） the sink location decision. The simulation results show that the performance of the CCLF algorithm is significantly similar to that of the optimal algorithm. Moreover, the CCLF algorithm requires less operation time compared with the optimal algorithm.

关键词： duty cycle latency sink wireless sensor networks

Proposal of High Gain, Reduced Stress with Low-duty-cycle Two-Input Boost Converter for Renewable Energy Systems

在线全文

学校读者我要写书评

暂无评论

Circuits and Systems 2016年第4期7卷 489-496页

作者： L. Chitra M. Karpagam K. Saranyadevi Department of Electrical and Electronics Engineering Dr Mahalingam College of Engineering and Technology Pollachi Tamil Nadu India Department of Electrical and Electronics Engineering Hindusthan College of Engineering and Technology Coimbatore Tamil Nadu India

A two-input boost converter with voltage multiplier cell is proposed in this paper. Then a family of two-input converters with and without voltage multiplier cell are derived and their results are compared to achieve high voltage gain, low duty cycle, and reduced voltage stress. From the analysis of different topologies, a modified two-input converter with two-stage voltage multiplier cell has good operating characteristics. The switch voltage stress and duty cycle of the modified converter is significantly very less than that of the other converter topologies. The modified DC-DC converter with 50% duty cycle achieves a voltage gain of 10 and the results are verified by using MATLAB/Simulink software.

关键词： Voltage Multiplier Cell (VMC) DC-DC Converter Boost Converter Simulink Voltage Gain Voltage Stress duty cycle

Command functions of open loop galvanometer scanners with optimized duty cycles

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2012年第4期2卷 34-39页

作者： V.F.Duma 3OM Optomechatronics Group Faculty of EngineeringAurel Vlaicu University of AradArad 310130Romania

The paper approaches the problem of the command functions of galvanometer-based scanners （GS） that are necessary to produce the linear plus parabolic scanning function of the GS, which we have proved previously to produce the highest possible duty cycle （i.e., time efficiency） of the device. We have completed this theoretical aspect （which contradicted what has been stated previously in the literature, where it has been considered that the linear plus sinusoidal scanning function was the best） with the experimental study of the most used scanning functions of the GSs （sawtooth, sinusoidal and triangular）, with applications in biomedical imaging, in particular in optical coherence tomography, demonstrating that the triangular function is always the best one to be applied, from both an optical and a mechanical point of view. In the present study the input voltage/command function which should be applied to the GS to produce the desired triangular scanning function （with controlled non-linearity for the fastest possible stop-and-turn portions） was determined analytically, in relationship with the active torque that drives the device. This command function is analyzed with regard to the specific, respectively required parameters of the GS： natural frequency and damping factor, respectively scan speed and amplitude. The modeling in an open loop control structure of the GS is finally discussed as a trade-off between using the highest possible duty cycle and minimizing the maximum peaks of the input voltage.

关键词： scanners galvanometer scanner optomechatronics scanning functions command func-tions duty cycle driving torque

DC-Gear:Gearing duty cycles in Delay-Constrained Wireless Sensor Networks

在线全文

学校读者我要写书评

暂无评论

China Communications 2011年第1期8卷 50-57页

作者：刘文远郭振格李镇江莫路锋肖崇蕙 Yanshan University Hong Kong University of Science and Technology Xi'an Jiaotong University

Many Wireless Sensor Network (WSN) systems are deployed in unattended areas using non-rechargeable *** enable sustainable operations,most WSN systems employ duty-cycling mechanisms,such as Low Power Listening (LPL).For reliable delivery of each packet with LPL,the sender has to transmit a preamble that is long enough to span over a complete sleep interval of the *** this way,the sensor nodes avoid idle listening,however,at the cost of remarkably increased end-to-end delay of multi-hop packet *** address this issue,in this paper we propose a new duty-cycling mechanism called ***-Gear exploits a "sleep less but save more" phenomenon,which means increasing the duty cycle in a timely and appropriate manner whileminimizing the overall energy cost and satisfying the end-to-end delay *** have implemented DC-Gear with TelosB motes and demonstrated its performance advantages through extensive experiments.

关键词： DC-Gear wireless sensor networks duty cycle energy cost delay-constrained

SR-MAC: A Low Latency MAC Protocol for Multi-Packet Transmissions in Wireless Sensor Networks

在线全文

学校读者我要写书评

暂无评论

Journal of Computer Science & Technology 2013年第2期28卷 329-342页

作者：唐宏伟曹建农刘雪峰孙彩霞 School of Computer National University of Defense Technology Department of Computing Hong Kong Polytechnic University

Event detection is one of the major applications of wireless sensor networks （WSNs）. Most of existing medium access control （MAC） protocols are mainly optimized for the situation under which an event only generates one packet on a single sensor node. When an event generates multiple packets on a single node, the performance of these MAC protocols degrades rapidly. In this paper, we present a new synchronous duty-cycle MAC protocol called SR-MAC for the event detection applications in which multiple packets are generated on a single node. SR-MAC introduces a new scheduling mechanism that reserves few time slots during the SLEEP period for the nodes to transmit multiple packets. By this approach, SR-MAC can schedule multiple packets generated by an event on a single node to be forwarded over multiple hops in one operational cycle without collision. We use event delivery latency （EDL） and event delivery ratio （EDR） to measure the event detection capability of the SR-MAC protocol. Through detailed ns-2 simulation, the results show that SR-MAC can achieve lower EDL, higher EDR and higher network throughput with guaranteed energy efficiency compared with R-MAC, DW-MAC and PR-MAC.

关键词： medium access control protocol synchronous duty cycle event delivery latency event delivery ratio