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排序方式: 共有95条查询结果,搜索用时 21 毫秒
1.
The objective of this study is to analyze volatile organic compound (VOC) concentrations in Taiwan's drinking water supply. Focusing on Taiwan's three major metropolitan areas--Taipei, Taichung and Kaohsiung (in the north, middle and south, respectively)--171 samples were taken from tap water and 68 from boiled water. Tests showed VOC concentrations were highest in Kaohsiung. This is due to different water sources and methods of treatment. Except for bromoform, trihalomethane (THM) concentrations were highest. Detection rates of toluene and 1,2-dichloroethane were slightly higher than other VOC compounds. VOC concentrations decreased significantly after water was boiled. THMs had a removal rate from 61% to 82%. The authors conclude that the three metropolitan areas contain significantly different levels of VOCs and that boiling can significantly reduce the presence of VOCs. Other sources of pollution that contaminate drinking water such as industrial plants and gas stations must be further investigated. 相似文献
2.
Molecular spiders are nanoscale walkers made with DNA enzyme legs attached to a common body. They move over a surface of DNA substrates, cleaving them and leaving behind product DNA strands, which they are able to revisit. Simple one-dimensional models of spider motion show significant superdiffusive motion when the leg-substrate bindings are longer-lived than the leg-product bindings. This gives the spiders potential as a faster-than-diffusion transport mechanism. However, analysis shows that single-spider motion eventually decays into an ordinary diffusive motion, owing to the ever increasing size of the region of cleaved products. Inspired by cooperative behavior of natural molecular walkers, we propose a symmetric exclusion process model for multiple walkers interacting as they move over a one-dimensional lattice. We show that when walkers are sequentially released from the origin, the collective effect is to prevent the leading walkers from moving too far backwards. Hence, there is an effective outward pressure on the leading walkers that keeps them moving superdiffusively for longer times, despite the growth of the product region. Multi-spider systems move faster and farther than single spiders or systems with multiple simple random walkers. 相似文献
3.
Mihajlo C. Stefanovic Jelena A. Anastasov Aleksandra M. Cvetkovic Goran T. Djordjevic 《Wireless Communications and Mobile Computing》2015,15(18):2141-2149
The outage performance of the amplify‐and‐forward relaying strategies over mutually uncorrelated extended generalized‐K fading channels is addressed in this paper. The attention is dedicated to the analyses of the noise‐limited and also interference‐limited environment. The new analytical expression for outage probability of observed relaying system in the presence of thermal noise is derived using the method for approximating equivalent signal‐to‐noise ratio. In addition, the outage performance is studied for the dual‐hop system when only the single dominant co‐channel interference is inherent at the relay and destination node. The correctness of the proposed mathematical derivations is verified by simulations. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
4.
Anna Fensel Slobodanka Tomic Vikash Kumar Milan Stefanovic Sergey V. Aleshin Dmitry O. Novikov 《Informatik-Spektrum》2013,36(1):46-57
As the urgent need for efficient and sustainable energy usage becomes ever more apparent, interest in Smart Homes is on the rise. The SESAME-S project (SEmantic SmArt Metering – Services for Energy Efficient Houses) uses semantically linked data to actively assist end-consumers in making well-informed decisions and controlling their energy consumption. By integrating smart metering and home automation functionality, SESAME-S works to effectively address the potential mass market of end-consumers with an easily customizable solution that can be widely implemented in domestic or business environments, with expected savings of over 20?% from the total energy bill. The developed system is a basis for conceptualizing, demonstrating, and evaluating a variety of innovative end-consumer services and their user interface paradigms. In this paper, we present the SESAME-S system as a whole and discuss the semantically enabled services, demonstrating that such systems may have broad acceptance in the future. The data obtained through such systems will be invaluable for future global energy-efficiency strategies and businesses. 相似文献
5.
An approach to the performance analyses of dual selection combining (SC) diversity receiver over correlated a ?m fading channels with the arbitrary parameters is presented. Fading between the diversity branches and interferers is correlated and distributed with α ? μ distribution. Infinite series expressions are obtained for the output SIR?s probability density function (PDF), cumulative distribution function (CDF) and an important measure of the system?s performances, the outage probability (OP). An average error probability is efficiently evaluated for coherent and non-coherent modulation schemes such as coherent frequency-shift keying (CFSK), coherent phase-shift keying (CPSK), binary frequency-shift keying (BFSK) and binary differentially phase-shift keying (BDPSK). Numerical results are presented to show the effects of various parameters such as fading severity, input SIR unbalance and the level of correlation between received desired signals and interferences on system?s performances. 相似文献
6.
Several inverter power circuits suitable for switched reluctance motor (SRM) drives are analyzed and compared. Five inverter circuits are considered with the objective of establishing the most appropriate topology for an SRM drive. The comparison is based on the peak voltage and peak current ratings of the DC link components. Because the power converter choice depends on the motor design, the converter analysis and selection are done for a high-speed, 6/2 SRM suitable for a spindle drive and a high-torque 8/6 motor. Experimental results obtained for a high-torque drive are included 相似文献
7.
Krishnan R. Stefanovic Victor R. Lindsay James F. 《Industry Applications, IEEE Transactions on》1983,(1):94-104
Efficient use of an inverter-fed induction motor drive necessitates a knowledge of the characteristics of the induction motor from a " control" point of view. The characteristics of both the voltage -and the current-source inverter-fed induction motor drive are investigated, neglecting the filter time constants in the link and feedback loops. Of particular interest is the role played by the voltage/current and frequency inputs. Their effects on variables that are not often discussed such as torque angle, stator real power, airgap flux- linkages and stator and rotor voltages/currents are studied. A by- product of this aspect of the study leads to the nature of feedback signals and their suitability for control purposes. It is also found that the link filter has little effect on relative suitability of these signals. A study of the current source induction motor drive dynamics for torque angle feedback is included. 相似文献
8.
Ioannou P.A. Stefanovic M. 《Intelligent Transportation Systems, IEEE Transactions on》2005,6(1):79-89
Almost every automobile company is producing vehicles with adaptive cruise control (ACC) system onboard that enables a vehicle to do automatic vehicle following in the longitudinal direction. The ACC system is designed for driver's comfort and safety and to operate with manually driven vehicles. These characteristics of ACC were found to have beneficial effects on the environment and traffic flow characteristics by acting as filters of a wide class of traffic disturbances. It has been argued that the smooth response of ACC vehicles to high-acceleration disturbances or large position errors creates large gaps between the ACC vehicle and the vehicle ahead inviting cut-ins and therefore generating additional disturbances that would not have been created if all vehicles had been manually driven. In this paper, we examine the effect of lane changes on the benefits suggested by Bose and Ioannou as well as the sensitivity of these benefits with respect to various variables such as the penetration of the ACC vehicles, level of traffic disturbances etc. We demonstrate, using theory, simulations, and experiments, that during lane changes, the smoothness of the ACC vehicle response attenuates the disturbances introduced by a cut-in or an exiting vehicle in a way that is beneficial to the environment when compared with similar situations where all vehicles are manually driven. We concluded that a higher number of possible cut-ins that may occur due to the larger gaps created during high-acceleration maneuvers by the vehicle in front of the ACC vehicle, will not annul the benefits obtained in the absence of such cut-ins when compared with the situation of similar maneuvers but with no cut-ins in the case of 100% manually driven vehicles. 相似文献
9.
The goal of this paper is to investigate the relation between object-oriented design choices and defects in software systems, with focus on a real-time telecommunication domain. The design choices are measured using the widely accepted metrics suite proposed by Chidamber and Kemerer for object oriented languages [S.R. Chidamber, C.F. Kemerer, A metrics suite for object oriented design, IEEE Transactions on Software Engineering 20 (6) (1994) 476-493].This paper reports the results of an extensive case study, which strongly reinforces earlier, mainly anecdotal, evidence that design aspects related to communication between classes can be used as indicators of the most defect-prone classes.Statistical models applicable for the non-normally distributed count data are used, such as Poisson regression, negative binomial regression, and zero-inflated negative binomial regression. The performances of the models are assessed using correlations, dispersion coefficients and Alberg diagrams.The zero-inflated negative binomial regression model based on response for a class shows the best overall ability to describe the variability of the number of defects in classes. 相似文献
10.
Cottonseed and soybean oils were partially hydrogenated using various commercial nickel catalysts. Methods were investigated
by which commercial catalysts can be changed with respect to the rate of reaction, selectivity ortrans-isomerization during hydrogenation of the oils. Catalysts which were treated with hydrogen sulfide produce considerably moretrans isomers but catalysts treated with air often cause higher selectivity ratios. Factors affecting the hydrogenation characteristics
of a catalyst are discussed.
Present Address: University of Cincinnati, Cincinnati, Ohio 相似文献