The Experts below are selected from a list of 109104 Experts worldwide ranked by ideXlab platform

Ian Oppermann - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Impulse Radio–Ultrawideband Based on Energy Collection on MAC Protocol Performance
    IEEE Transactions on Vehicular Technology, 2009
    Co-Authors: Jussi Haapola, Alberto Rabbachin, Leonardo Goratti, Carlos Pomalaza-raez, Ian Oppermann
    Abstract:

    In this paper, we analyze the effects of the probabilities of detection, false alarm, and frame collision survival (in the presence of simultaneous transmissions) on medium access control (MAC) protocols using impulse-radio-ultrawideband (IR-UWB) Energy-Collection noncoherent receivers. The MAC protocols that were considered are all IEEE 802.15.4 compatible, i.e., the IEEE 802.15.4a optional UWB clear-channel-assessment mode, the IEEE 802.15.4a ALOHA mode, and a protocol termed preamble sense multiple access (PSMA). The impact on the network throughput, Energy consumption, and delay are analytically derived and verified by simulation. The results show that these effects have a considerable impact on the performance of IR-UWB MAC protocols, and a classical analysis does not properly evaluate the protocolspsila performances. The results compare the performances of the MAC protocols and highlight a number of issues with regard to adapting narrowband protocols to UWB systems. The probability of frame collision survival on simultaneous transmissions is shown to have a significant impact on the performance of a MAC protocol. The comparison shows superior performance of the PSMA protocol under typical wireless-sensor-network operation ranges.

  • Synchronization analysis for UWB systems with a low-complexity Energy Collection receiver
    2004 International Workshop on Ultra Wideband Systems Joint with Conference on Ultra Wideband Systems and Technologies. Joint UWBST & IWUWBS 2004 (IEE, 2004
    Co-Authors: Alberto Rabbachin, Ian Oppermann
    Abstract:

    This paper presents analysis of a synchronization scheme for a low complexity, noncoherent ultrawideband (UWB) receiver. The receiver has very low complexity and the synchronization scheme does not increase drastically the complexity. A theoretical formula that helps in the definition of the preamble length is proposed and its validity provided for reasonable signal to noise ratio (SNR). The performance is examined in terms of probability of synchronization for both AWGN and Saleh-Valenzuela channel models. The synchronization results together with the BER performance show the suitability of this simple receiver structure for low cost devices in sensor networks.

Stephen William Rees - One of the best experts on this subject based on the ideXlab platform.

  • Factors influencing Collection performance of near surface interseasonal ground Energy Collection and storage systems
    Geomechanics for Energy and the Environment, 2016
    Co-Authors: J.j. Muñoz-criollo, Peter John Cleall, Stephen William Rees
    Abstract:

    The influence of surface boundary conditions, varying climatic conditions and engineering material parameters on the Collection performance of near surface interseasonal ground Energy Collection and storage systems are investigated. In particular, the performance of a proposed design of an interseasonal heat storage system which has also been investigated by others as part of a full scale demonstration project is considered. A numerical model is developed and validated against field data. It is then applied to undertake a series of simulations with varying system parameters. It is found that (i) higher values of thermal conductivity of the storage layer result in increased storage of thermal Energy and lower peak temperatures, (ii) system heat losses are strongly influenced by the performance of insulation layers, (iii) warmer climatic conditions provide more thermal Energy available to be stored; however, changes in the amplitude of seasonal air temperature variations have an effect on the rate of Collection of thermal Energy and (iv) the use of correct surface boundary conditions is critical in modelling the dynamics of these systems.

Azharul Karim - One of the best experts on this subject based on the ideXlab platform.

  • Effect of the Orientation Schemes of the Energy Collection Element on the Optical Performance of a Parabolic Trough Concentrating Collector
    Energies, 2018
    Co-Authors: Majedul Islam, Prasad K.d.v. Yarlagadda, Azharul Karim
    Abstract:

    While the circular shape is currently the proven optimum design of the Energy Collection element (ECE) of a parabolic trough collector, that is yet to be confirmed for parabolic trough concentrating collectors (PTCCs) like trough concentrating photovoltaic collectors and hybrid photovoltaic/thermal collectors. Orientation scheme of the ECE is expected to have significant effect on the optical performance including the irradiance distribution around the ECE and the optical efficiency, and therefore, on the overall Energy performance of the PTCC. However, little progress addressing this issue has been reported in the literature. In this study, a thorough investigation has been conducted to determine the effect of the orientation schemes of ECE on the optical performance of a PTCC applying a state-of-the-art Monte Carlo ray tracing (MCRT) technique. The orientation schemes considered are a flat rectangular target and a hollow circular, semi-circular, triangular, inverted triangular, rectangular and rectangle on semi-circle (RSc). The effect of ECE defocus, Sun tracking error and trough rim angle on the optical performance is also investigated. The MCRT study reveals that the ECE orientation schemes with a curved surface at the trough end showed much higher optical efficiency than those with a linear surface under ideal conditions. ECEs among the linear surface group, the inverted triangular orientation exhibited the highest optical efficiency, whereas the flat and triangular ones exhibited the lowest optical efficiency, and the rectangular one was in between them. In the event of defocus and tracking errors, a significant portion of the concentrated light was observed to be intercepted by the surfaces of the rectangular and RSc ECEs that are perpendicular to the trough aperture. This is an extended version of a published work by the current authors, which will help to design an optically efficient ECE for a parabolic trough concentrating collector.

Alberto Rabbachin - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Impulse Radio–Ultrawideband Based on Energy Collection on MAC Protocol Performance
    IEEE Transactions on Vehicular Technology, 2009
    Co-Authors: Jussi Haapola, Alberto Rabbachin, Leonardo Goratti, Carlos Pomalaza-raez, Ian Oppermann
    Abstract:

    In this paper, we analyze the effects of the probabilities of detection, false alarm, and frame collision survival (in the presence of simultaneous transmissions) on medium access control (MAC) protocols using impulse-radio-ultrawideband (IR-UWB) Energy-Collection noncoherent receivers. The MAC protocols that were considered are all IEEE 802.15.4 compatible, i.e., the IEEE 802.15.4a optional UWB clear-channel-assessment mode, the IEEE 802.15.4a ALOHA mode, and a protocol termed preamble sense multiple access (PSMA). The impact on the network throughput, Energy consumption, and delay are analytically derived and verified by simulation. The results show that these effects have a considerable impact on the performance of IR-UWB MAC protocols, and a classical analysis does not properly evaluate the protocolspsila performances. The results compare the performances of the MAC protocols and highlight a number of issues with regard to adapting narrowband protocols to UWB systems. The probability of frame collision survival on simultaneous transmissions is shown to have a significant impact on the performance of a MAC protocol. The comparison shows superior performance of the PSMA protocol under typical wireless-sensor-network operation ranges.

  • Synchronization analysis for UWB systems with a low-complexity Energy Collection receiver
    2004 International Workshop on Ultra Wideband Systems Joint with Conference on Ultra Wideband Systems and Technologies. Joint UWBST & IWUWBS 2004 (IEE, 2004
    Co-Authors: Alberto Rabbachin, Ian Oppermann
    Abstract:

    This paper presents analysis of a synchronization scheme for a low complexity, noncoherent ultrawideband (UWB) receiver. The receiver has very low complexity and the synchronization scheme does not increase drastically the complexity. A theoretical formula that helps in the definition of the preamble length is proposed and its validity provided for reasonable signal to noise ratio (SNR). The performance is examined in terms of probability of synchronization for both AWGN and Saleh-Valenzuela channel models. The synchronization results together with the BER performance show the suitability of this simple receiver structure for low cost devices in sensor networks.

John D. Garrison - One of the best experts on this subject based on the ideXlab platform.

  • A program for calculation of solar Energy Collection by fixed and tracking collectors
    Solar Energy, 2002
    Co-Authors: John D. Garrison
    Abstract:

    Abstract socol , a realistic and versatile fortran program, has been developed to estimate net solar Energy collected by a solar collector per unit Collection area. This program was developed to study the properties of various solar collectors. It is made useful to a wide spectrum of users by allowing them to choose any or all of 15 possible solar collector types for calculation and comparison. Additional collectors can be included without undue labor. Either or both of two selective absorbers can be selected for Energy Collection calculations. socol allows input for a third selective absorber. socol is programmed to use solar radiation and surface meteorological data taken from The National Solar Radiation Data Base (NSRDB) for 239 stations over the USA. It can be adjusted to read other data sets. It takes 20 s on a Compaq Presario 2700 1.13 GHz computer to calculate net solar Energy Collection per unit area for one solar collector design using each of two selective absorbers at five fixed absorber temperatures for all the daylight hours of 1 year at one location. The program output includes sums of solar Energy Collection for each day, month and year along with averages and distributions. Averages and distributions for the solar radiation and surface meteorological data are also obtained so solar Energy Collection can be related to these data. socol can be downloaded from the website: www.sci.sdsu.edu/SOCOL/ .