期刊文献+
共找到341篇文章
< 1 2 18 >
每页显示 20 50 100
Exploiting the Cellular Infrastructure for Data Transmission in Smart Metering Systems 被引量:1
1
作者 Athanasios Giannakopoulos Panayotis G. Cottis 《Journal of Computer and Communications》 2016年第7期31-41,共11页
To implement the access and backhaul networks for Smart Metering (SM) systems various technologies are combined with the existing communications infrastructure. This paper deals with data transmission in SM systems, f... To implement the access and backhaul networks for Smart Metering (SM) systems various technologies are combined with the existing communications infrastructure. This paper deals with data transmission in SM systems, focusing on how the existing cellular networks infrastructure is employed to implement SM access communication networks. The analysis aims at analyzing the role of the cellular communications infrastructure taking into account the spatial distribution and installation points of the smart meters, the urban and topological characteristics of the SM deployment areas and the common practice so far followed by the utilities. It is demonstrated that cellular communications, either exclusively or combined with power line communications, enable immediate and scalable deployment of SM access communication networks at low installation cost, thus constituting the basic option for the implementation of smart metering. 展开更多
关键词 Smart metering (SM) SM Access Communication Networks Cellular Communication Networks Power Line Communications
下载PDF
New Hybrid IoT LoRaWAN/IRC Sensors:SMARTWater Metering System
2
作者 Vlastimil Slany Petr Koudelka +6 位作者 Eva Krcalova Jan Jobbagy Lukas Danys Rene Jaros Zdenek Slanina Michal Prauzek Radek Martinek 《Computers, Materials & Continua》 SCIE EI 2022年第6期5201-5217,共17页
The massive development of internet of things(IoT)technologies is gaining momentum across all areas of their possible deployment—spanning from Industry 4.0 to eHealth,smart city,agriculture or waste management.This o... The massive development of internet of things(IoT)technologies is gaining momentum across all areas of their possible deployment—spanning from Industry 4.0 to eHealth,smart city,agriculture or waste management.This ongoing development is further pushed forward by the gradual deployment of 5G networks.With 5G capable smart devices,it will be possible to transfer more data with shorter latency thereby resulting in exciting new use cases such as Massive IoT.Massive-IoT(low-power wide area network-LPWAN)enables improved network coverage,long device operational lifetime and a high density of connections.Despite all the advantages of massive-IoT technology,there are certain cases where the original concept cannot be used.Among them are dangerous explosive environments or issues caused by subsurface deployment(operation during winter months or dense greenery).This article presents the concept of a hybrid solution of IoT LoRaWAN(long range wide area network)/IRC-VLC(infrared communication,visible light communication)technology,which combines advantages of both technologies according to the deployment scenario. 展开更多
关键词 IRC/VLC LoRaWAN LPWAN massive IoT smart metering
下载PDF
Control performance and energy saving of multi-level pressure switching control system based on independent metering control
3
作者 Cao Xiaoming Yao Jing +1 位作者 Sha Tong Wang Pei 《High Technology Letters》 EI CAS 2020年第2期224-234,共11页
Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure sw... Aiming at the problem of large energy consumption in hydraulic control system with large load and variable working conditions,based on the multi-level pressure switching control system(MPSCS),a multi-level pressure switching control system based on independent metering control is proposed combined with the independent metering control technology.The configuration principle of the system is given,the mathematical model of this system is established,and the control strategy of the system under 4 different working quadrants is put forward.Finally,the control performance and energy saving characteristics of the system are tested.The test results show that the switching of high and low pressure power supply has a certain effect on the response of step position and ramp position under impedance working condition.The displacement curves show slow climbing or abrupt change of ramp position,and the position accuracy is less than 1 mm.The multi-level pressure switching control system based on independent metering control can recover and store energy under the transcendence working conditions.The control accuracy is about 1 mm,and the energy recovery rate is about 70%~80%. 展开更多
关键词 MULTI-LEVEL pressure INDEPENDENT metering CONTROL DISPLACEMENT CONTROL energy SAVING hydraulic switching system
下载PDF
Design and experiment of the pneumatic cylinder type precision metering system for wheat
4
作者 Anas Dafaallah Abdallah Qingxi Liao +1 位作者 Elebaid Jabir Ibrahim Lei Wang 《International Journal of Agricultural and Biological Engineering》 SCIE 2023年第5期88-94,共7页
The main goal of this study was to design a pneumatic cylindrical-type metering device with six-rows for wheat precision and to analyze its output under different rotating speeds and vacuum pressure values.The effect ... The main goal of this study was to design a pneumatic cylindrical-type metering device with six-rows for wheat precision and to analyze its output under different rotating speeds and vacuum pressure values.The effect of the pressure,rotating speed and rows on seed suction,retention and dropping was shown inspected.Six levels of rotating speed(5,10,15,20,25 and 30 r/min.)combined with the applying of different vacuum pressures(1.8,2.1,2.4,2.7,3.0,and 3.3 kPa)were inspected to detect the optimum pressure which was adequate for seed sucking at each speed.In addition,to predict the vacuum pressure corresponding with each rotating speed,a regression model was developed.Based on seed mass analysis,statistical differences under the influence of velocities and negative pressure were found at 5 percent significance according to Duncan’s Test,whereas the differences were existed between and within rows.Results revealed that the highest seed mass means of 19.02 g and 22.64 g were obtained by row1while the lowest means of 18.02 g and 21.49 g were attained by row6 under the effect of the speed and vacuum pressure,respectively.The noticeable variation between row1 and row 6,particularly under high speeds(25 and 30 r/min),might be returned to the truth that row 1 was closer to vacuum inlet,and row 6 was the farthest one.Results concluded that the multiple-row pneumatic cylinder with oblong shape seed nozzle was found to be capable for single seed picking with a small rows variation but without seed damage. 展开更多
关键词 Multi-rows cylinder pneumatic metering device WHEAT PRECISION
原文传递
Simulation Analysis of Characteristics for Independent Metering Control System Based on Downstream Compensation
5
作者 Guotai Zhang Jie Xu +1 位作者 Jing Yang Kailei Liu 《World Journal of Engineering and Technology》 2019年第3期536-547,共12页
Aiming at the shortcomings of the separate meter in and separate meter out?hydraulic system, a new type of independent metering control system is proposed by referring to the principle of load-sensing system. The valv... Aiming at the shortcomings of the separate meter in and separate meter out?hydraulic system, a new type of independent metering control system is proposed by referring to the principle of load-sensing system. The valve group unit in the system is designed, and the AMESim/Matlab cosimulation model of the component and system is established. The actuator speed control, energy consumption and anti-flow saturation characteristics of the system are discussed. The simulation result shows that the system proposed in this article can achieve?better performances. 展开更多
关键词 INDEPENDENT metering Control Pressure COMPENSATION COSIMULATION
下载PDF
Independent metering systems
6
作者 Jürgen Weber 《International Journal of Hydromechatronics》 2018年第1期91-106,共16页
Measures of individualisation and integration offer a great potential for further development and optimisation in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. To ... Measures of individualisation and integration offer a great potential for further development and optimisation in hydraulic drive technology. Advantages are seen especially for energy efficiency and functionality. To exploit these benefits the independent metering technology appears to be very attractive which motivates the extensive research on this topic during the last decade. This article starts with a brief overview on common hardware arrangements and general control approaches. Furthermore an approach to the safety evaluation of novel independent metering systems is given. Afterwards different application examples are presented, such as a cardboard packaging press in the area of stationary machines and in the fields of mobile machines a working implement of an excavator and an active steering system for tractors. The article ends with a brief summary of the valve requirements for independent metering. 展开更多
关键词 individual drives displacement control independent metering.
原文传递
Intelligent Energy Utilization Analysis Using IUA-SMD Model Based Optimization Technique for Smart Metering Data
7
作者 K.Rama Devi V.Srinivasan +1 位作者 G.Clara Barathi Priyadharshini J.Gokulapriya 《Journal of Harbin Institute of Technology(New Series)》 CAS 2024年第1期90-98,共9页
Smart metering has gained considerable attention as a research focus due to its reliability and energy-efficient nature compared to traditional electromechanical metering systems. Existing methods primarily focus on d... Smart metering has gained considerable attention as a research focus due to its reliability and energy-efficient nature compared to traditional electromechanical metering systems. Existing methods primarily focus on data management,rather than emphasizing efficiency. Accurate prediction of electricity consumption is crucial for enabling intelligent grid operations,including resource planning and demandsupply balancing. Smart metering solutions offer users the benefits of effectively interpreting their energy utilization and optimizing costs. Motivated by this,this paper presents an Intelligent Energy Utilization Analysis using Smart Metering Data(IUA-SMD)model to determine energy consumption patterns. The proposed IUA-SMD model comprises three major processes:data Pre-processing,feature extraction,and classification,with parameter optimization. We employ the extreme learning machine(ELM)based classification approach within the IUA-SMD model to derive optimal energy utilization labels. Additionally,we apply the shell game optimization(SGO)algorithm to enhance the classification efficiency of the ELM by optimizing its parameters. The effectiveness of the IUA-SMD model is evaluated using an extensive dataset of smart metering data,and the results are analyzed in terms of accuracy and mean square error(MSE). The proposed model demonstrates superior performance,achieving a maximum accuracy of65.917% and a minimum MSE of0.096. These results highlight the potential of the IUA-SMD model for enabling efficient energy utilization through intelligent analysis of smart metering data. 展开更多
关键词 electricity consumption predictive model data analytics smart metering machine learning
下载PDF
SmartMicro Grid Energy System Management Based on Optimum Running Cost for Rural Communities in Rwanda
8
作者 Fabien Mukundufite Jean Marie Vianney Bikorimana Alexander Kyaruzi Lugatona 《Energy Engineering》 EI 2024年第7期1805-1821,共17页
The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by 2024.However,the aforementioned goal is challenged by households that are scattered in re... The governmental electric utility and the private sector are joining hands to meet the target of electrifying all households by 2024.However,the aforementioned goal is challenged by households that are scattered in remote areas.So far,Solar Home Systems(SHS)have mostly been applied to increase electricity access in rural areas.SHSs have continuous constraints to meet electricity demands and cannot run income-generating activities.The current research presents the feasibility study of electrifying Remera village with the smart microgrid as a case study.The renewable energy resources available in Remera are the key sources of electricity in that village.The generation capacity is estimated based on the load profile.The microgrid configurations are simulated with HOMER,and the genetic algorithm is used to analyze the optimum cost.By analyzing the impact of operation and maintenance costs,the results show that the absence of subsidies increases the levelized cost of electricity(COE)five times greater than the electricity price from the public utility.The microgrid made up of PV,diesel generator,and batteries proved to be the most viable solution and ensured continuous power supply to customers.By considering the subsidies,COE reaches 0.186$/kWh,a competitive price with electricity from public utilities in Rwanda. 展开更多
关键词 Load demand load profile optimum running cost power demand satisfaction smart meters and smart micro grid
下载PDF
Functional Confirmation Using a Medical X-Ray System of a Semiconductor Survey Meter
9
作者 Katsunao Suzuki Toru Negishi +2 位作者 Yoh Kato Yasuhisa Kono Michiharu Sekimoto 《Open Journal of Radiology》 2024年第1期1-13,共13页
In recent years, semiconductor survey meters have been developed and are in increasing demand worldwide. This study determined if it is possible to use the X-ray system installed in each medical facility to calculate ... In recent years, semiconductor survey meters have been developed and are in increasing demand worldwide. This study determined if it is possible to use the X-ray system installed in each medical facility to calculate the time constant of a semiconductor survey meter and confirm the meter’s function. An additional filter was attached to the medical X-ray system to satisfy the standards of N-60 to N-120, more copper plates were added as needed, and the first and second half-value layers were calculated to enable comparisons of the facility’s X-ray system quality with the N-60 to N-120 quality values. Next, we used a medical X-ray system to measure the leakage dose and calculate the time constant of the survey meter. The functionality of the meter was then checked and compared with the energy characteristics of the meter. The experimental results showed that it was possible to use a medical X-ray system to reproduce the N-60 to N-120 radiation quality values and to calculate the time constant from the measured results, assuming actual leakage dosimetry for that radiation quality. We also found that the calibration factor was equivalent to that of the energy characteristics of the survey meter. 展开更多
关键词 Semiconductor Survey Meter Functional Confirmation Medical X-Ray system Calibration Factor Time Constant
下载PDF
Design and Application of Automatic Test System of Soil Water Characteristic Curve
10
作者 唐玉邦 徐磊 +3 位作者 虞利俊 裴勤 王恒义 黄万喜 《Agricultural Science & Technology》 CAS 2014年第11期2026-2029,共4页
[Objective] In order to better meet the requirement of crops on a more and more accurate water content under various planting environment of modern agri-culture, an automatic test system of soil water characteristic c... [Objective] In order to better meet the requirement of crops on a more and more accurate water content under various planting environment of modern agri-culture, an automatic test system of soil water characteristic curve was designed by combining the conceptions of soil moisture content and soil water potential. [Method] Electronic soil moisture tension meter was used to determine the real-time tension value of soil moisture in the tested container, and the electronic Weigh sensor was used to determine soil Weigh. Minusing method was used to calculate soil moisture content, based on which the soil water characteristic curve was plotted. [Result] Through the filed survey of 2 different kinds of soil in Jiangsu Province, the results were as fol ows: soil of different composition showed different trend in soil water characteristic curve that the soil water characteristic relation of the sandy soil in the old course of the Yel ow River in Xuzhou was Y=-0.000 2X3+0.027 7X2-1.644 5X+38.161, R2=0.991 9; while the soil water characteristic relation of the saline-alkali soil in Jinhai Farm of Dafeng was Y=-0.00 2X2-0.426X+39.905, R2=0.991 3. [Con-clusion] The automatic test system of soil water characteristic curve soil water char-acteristics curve could reflect soil moisture content and soil water potential, as wel as reflect the effectiveness of soil water to plant growth, providing basis for the sci-entific irrigation. 展开更多
关键词 Soil water characteristics curve Water tension meter Automatic detec-tion Wireless charging
下载PDF
Discrete Particle Simulation of Gas-Solid Flow in Air-Blowing Seed Metering Device 被引量:7
11
作者 Zhengquan Li Pei Zhang +3 位作者 Yongchang Sun Chenglin Zheng Liang Xu Dianyu E 《Computer Modeling in Engineering & Sciences》 SCIE EI 2021年第6期1119-1132,共14页
In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The... In this paper,the gas and seed flow characters in the air-blowing seed metering device are investigated by using the coupled computational fluid dynamics and discrete element method(CFD-DEM)in three dimensions(3D).The method of establishing boundary model based on the computer-aided design(CAD)drawing,has been used to build the boundary model of seed metering device.The 3D laser scanning technique and multi-element method are adopted to establish the particle model.Through a combined numerical and experimental effort,using 3D CFD-DEM software,which is based on the in-house codes,the mechanisms governing the gas and solid dynamic behaviors in the seed metering device have been studied.The gas velocity field and the effect of different rotational speeds and air pressures on the seeding performance and particle velocity have been studied,similar agreements between numerical and experimental results are gained.This reveals that the 3D CFD-DEM model established is able to predict the performance of the air-blowing seed metering device.It can be used to design and optimize the air-blowing seed metering device and other similar agriculture devices. 展开更多
关键词 Seed metering device CFD-DEM CAD SIMULATION gas-solid flow
下载PDF
Investigation into the Independent Metering Control Performance of a Twin Spools Valve with Switching Technology-controlled Pilot Stage 被引量:6
12
作者 Qi Zhong Huiming Bao +3 位作者 Yanbiao Li Haocen Hong Bin Zhang Huayong Yang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2021年第5期226-242,共17页
In hydraulic area,independent metering control(IMC)technology is an effective approach to improve system efficiency and control flexibility.In addition,digital hydraulic technology(DHT)has been verified as a reasonabl... In hydraulic area,independent metering control(IMC)technology is an effective approach to improve system efficiency and control flexibility.In addition,digital hydraulic technology(DHT)has been verified as a reasonable method to optimize system dynamic performance.Integrating these two technologies into one component can combine their advantages together.However,few works focused on it.In this paper,a twin spools valve with switching technologycontrolled pilot stage(TSVSP)is presented,which applied DHT into its pilot stage while appending IMC into its main stage.Based on this prototype valve,a series of numerical and experiment analysis of its IMC performance with both simulated load and excavator boom cylinder are carried out.Results showed fast and robust performance of pressure and flow compound control with acceptable fluctuation phenomenon caused by switching technology.Rising time of flow response in excavator cylinder can be controlled within 200 ms,meanwhile,the recovery time of rod chamber pressure under suddenly changed condition is optimized within 250 ms.IMC system based on TSVSP can improve both dynamic performance and robust characteristics of the target actuator so it is practical in valve-cylinder system and can be applied in mobile machineries. 展开更多
关键词 High speed on/off valve(HSV) Digital hydraulic technology(DHT) Switching pilot control Twin spools valve Independent metering control(IMC)
下载PDF
Robust Non-fragile PID Controller Design for the Stroke Regulation of Metering Pumps 被引量:3
13
作者 余世明 吴江江 张端 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2011年第1期83-88,共6页
This job focuses on the stroke regulation of a class of high-precision metering pumps.A parametertuning method of robust non-fragile PID(proportional-integral-derivative)controllers is proposed with the assumption t... This job focuses on the stroke regulation of a class of high-precision metering pumps.A parametertuning method of robust non-fragile PID(proportional-integral-derivative)controllers is proposed with the assumption that a PID controller has additive gain perturbations.An H-infinite robust PID controller can be obtained by solving a linear matrix inequality.This approach can guarantee that the closed-loop control systems is asymptotically stable and the H-infinite norm of the transfer function from the disturbance to the output of a controlled system is less than a given constant to attenuate disturbances.The simulation case shows that the control performance of the proposed strategy is significantly better than the traditional PID approach in the situation with perturbations of controller parameters. 展开更多
关键词 metering pump stroke regulation H-infinite robust control PID control NON-FRAGILE
下载PDF
Iterative learning control approach for ramp metering 被引量:4
14
作者 ZhongshengHOU JianxinXU 《控制理论与应用(英文版)》 EI 2005年第1期27-34,共8页
An iterative learning control scheme is developed to the traffic densitycontrol in a macroscopic level freeway environment. With rigorous analysis, the proposed intelligentcontrol scheme guarantees the asymptotic conv... An iterative learning control scheme is developed to the traffic densitycontrol in a macroscopic level freeway environment. With rigorous analysis, the proposed intelligentcontrol scheme guarantees the asymptotic convergence of the traffic density to the desired one. Thecontrol scheme is applied to a freeway model, and simulation results confirm the efficacy of theproposed approach. 展开更多
关键词 macroscopic traffic flow model traffic density control iterative learningcontrol freeway ramp metering
下载PDF
Adaptive fault diagnosis of sucker rod pump systems based on optimal perceptron and simulation data 被引量:2
15
作者 Xiao-Xiao Lv Han-Xiang Wang +2 位作者 Zhang Xin Yan-Xin Liu Peng-Cheng Zhao 《Petroleum Science》 SCIE CAS CSCD 2022年第2期743-760,共18页
A highly precise and timely diagnosis technology can help effectively monitor and adjust the sucker rod production system(SRPS)used in oil wells to ensure a safe and efficient production.The current diagnosis method i... A highly precise and timely diagnosis technology can help effectively monitor and adjust the sucker rod production system(SRPS)used in oil wells to ensure a safe and efficient production.The current diagnosis method is pattern recognition of a dynamometer card(DC)based on feature extraction and perceptron.The premise of this method is that the training and target data have the same distribution.However,the training data are collected from a field SRPS with different system parameters designed to adapt to production conditions,which may significantly affect the diagnostic accuracy.To address this issue,in this study,an improved model of the sucker rod string(SRS)is derived by adding faultparameter dimensions,with which DCs under 16 working conditions could be generated.Subsequently an adaptive diagnosis method is proposed by taking simulated DCs generated near the working point of the target SRPS as training data.Meanwhile,to further improve the accuracy of the proposed method,the DC features are improved by relative normalization and using additional features of the DC position to increase the distance between different types of samples.The parameters of the perceptron are optimized to promote its discriminability.Finally,the accuracy and real-time performance of the proposed adaptive diagnosis method are validated using field data. 展开更多
关键词 Sucker rod pump Dynamometer card Adaptive fault diagnosis Sucker rod dynamics Output metering
下载PDF
Technologies Behind the Smart Grid and Internet of Things: A System Survey 被引量:1
16
作者 Kuldeep Sharma Arun Malik +3 位作者 Isha Batra A.S.M.Sanwar Hosen Md Abdul Latif Sarker Dong Seog Han 《Computers, Materials & Continua》 SCIE EI 2023年第6期5049-5072,共24页
Electric smart grids enable a bidirectional flow of electricity and information among power system assets.For proper monitoring and con-trolling of power quality,reliability,scalability and flexibility,there is a need... Electric smart grids enable a bidirectional flow of electricity and information among power system assets.For proper monitoring and con-trolling of power quality,reliability,scalability and flexibility,there is a need for an environmentally friendly system that is transparent,sustainable,cost-saving,energy-efficient,agile and secure.This paper provides an overview of the emerging technologies behind smart grids and the internet of things.The dependent variables are identified by analyzing the electricity consumption patterns for optimal utilization and planning preventive maintenance of their legacy assets like power distribution transformers with real-time parameters to ensure an uninterrupted and reliable power supply.In addition,the paper sorts out challenges in the traditional or legacy electricity grid,power generation,transmission,distribution,and revenue management challenges such as reduc-ing aggregate technical and commercial loss by reforming the existing manual or semi-automatic techniques to fully smart or automatic systems.This article represents a concise review of research works in creating components of the smart grid like smart metering infrastructure for postpaid as well as in prepaid mode,internal structure comparison of advanced metering methods in present scenarios,and communication systems. 展开更多
关键词 Electricity consumption BIDIRECTIONAL advanced meter infrastructure energy internet of things smart grid smart meter
下载PDF
Residential PV capacity estimation and power disaggregation using net metering measurements 被引量:1
17
作者 Bo Liu Jianmin Tian +3 位作者 Wenpeng Luan Yi Gao Xiaohui Wang Shuai Luo 《Global Energy Interconnection》 EI CAS CSCD 2022年第6期590-603,共14页
As the intermittency and uncertainty of photovoltaic(PV)power generation poses considerable challenges to the power system operation,accurate PV generation estimates are critical for the distribution operation,mainten... As the intermittency and uncertainty of photovoltaic(PV)power generation poses considerable challenges to the power system operation,accurate PV generation estimates are critical for the distribution operation,maintenance,and demand response program implementation because of the increasing usage of distributed PVs.Currently,most residential PVs are installed behind the meter,with only the net load available to the utilities.Therefore,a method for disaggregating the residential PV generation from the net load data is needed to enhance the grid-edge observability.In this study,an unsupervised PV capacity estimation method based on net metering data is proposed,for estimating the PV capacity in the customer’s premise based on the distribution characteristics of nocturnal and diurnal net load extremes.Then,the PV generation disaggregation method is presented.Based on the analysis of the correlation between the nocturnal and diurnal actual loads and the correlation between the PV capacity and their actual PV generation,the PV generation of customers is estimated by applying linear fitting of multiple typical solar exemplars and then disaggregating them into hourly-resolution power profiles.Finally,the anomalies of disaggregated PV power are calibrated and corrected using the estimated capacity.Experiment results on a real-world hourly dataset involving 260 customers show that the proposed PV capacity estimation method achieves good accuracy because of the advantages of robustness and low complexity.Compared with the state-of-the-art PV disaggregation algorithm,the proposed method exhibits a reduction of over 15%for the mean absolute percentage error and over 20%for the root mean square error. 展开更多
关键词 Behind-the-meter Residential photovoltaic Capacity estimation Power disaggregation Net metering
下载PDF
Embedded TLS 1.2 Implementation for Smart Metering & Smart Grid Applications 被引量:1
18
作者 Atta Kofi Nsiah Axel Sikora +1 位作者 Andreas Walz Artem Yushev 《Journal of Electronic Science and Technology》 CAS CSCD 2015年第4期373-378,共6页
Digital networked communications are the key to all Internet-of-things applications, but especially to smart metering systems and the smart grid. In order to ensure a safe operation of systems and the privacy of users... Digital networked communications are the key to all Internet-of-things applications, but especially to smart metering systems and the smart grid. In order to ensure a safe operation of systems and the privacy of users, the transport layer security (TLS) protocol, a mature and well standardized solution for secure communications, may be used. We implemented the TLS protocol in its latest version in a way suitable for embedded and resource-constrained systems. This paper outlines the challenges and opportunities of deploying TLS in smart metering and smart grid applications and presents performance results of our TLS implementation. Our analysis shows that given an appropriate implementation and configuration, deploying TLS in constrained smart metering systems is possible with acceptable overhead. 展开更多
关键词 Embedded software smart grids smart metering transport layer security.
下载PDF
Ratio K: a New Way of Metering and Evaluating the Risk and Return of Stock Investment 被引量:1
19
作者 朱淑珍 朱静怡 《Journal of Donghua University(English Edition)》 EI CAS 2003年第2期129-136,共8页
Although widely used, both the Markowitz model and VAR (Value at Risk) model have some limitations in evaluating the risk and return of stock investment. By the analysis of the conceptions of risk and return, together... Although widely used, both the Markowitz model and VAR (Value at Risk) model have some limitations in evaluating the risk and return of stock investment. By the analysis of the conceptions of risk and return, together with the three hypotheses of technological analysis, a novelty model of metering and evaluating the risk and return of stock investment is established. The major indicator of this model , risk-return ratio K, combines the characteristic indicators of risk and return. Regardless of the form of the risk-return probability density functions, this indicator K can always reflect the risk-return performances of the invested stocks clearly and accurately. How to use the model to make optimum investment and how to make portfolio combined with clustering analysis is also explained. 展开更多
关键词 Stock investment risk and return risk-return ratio K metering and evaluating
下载PDF
Design of Metering Device Key Parts of Pneumatic Grass Seeder 被引量:1
20
作者 Zhai Gaixia Wang Zhenhua He Gang Liu Guilin Yang Li 《Journal of Earth Science and Engineering》 2015年第5期289-295,共7页
Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and cent... Based on the mechanical and physical properties study of forage grass seeds, multi-line with one-device type metering device was designed. It was composed of adjustable screw, stirrer, metering device housing and central metering sheave and so on. The sowing rate can be set by turning the screw to change the working length of the central metering sheave relative to the metering device housing. The stirrer inside of the sheave housing is used to prevent seeds overhead. And metering of different sizes of seed is adjusted by changing the position of internal components of the slot wheel mechanism. Innovative design on the structure of the central metering sheave was finished. According to the structure parameters and physical characteristic parameters, different seed sowing rate of per hectares was calculated. And then the working length scale of the central metering groove wheel was made. And there is a one-to-one correspondence between scale values and sowing quantity per hectare of different kinds of seed. 展开更多
关键词 SEEDER metering device central metering sheave sowing rate.
下载PDF
上一页 1 2 18 下一页 到第
使用帮助 返回顶部