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An Improved Algorithm for Matrix Bandwidth and Profile Reduction in Finite Element Analysis
Qing Wang;Xiao-Wei Shi
PIER Letters , 2009, DOI: 10.2528/PIERL09042305
Abstract: In finite element analysis, methods for the solution of sparse linear systems of equations usually start out with reordering the coefficient matrix to reduce its bandwidth or profile. The location of pseudo-peripheral nodes is an important factor in the bandwidth and profile reduction algorithm. This paper presents a heuristic parameter, called the "width-depth ratio" and denoted by . With such a parameter, suitable pseudo-peripheral nodes could be found; the distance between which could be much close to or even to be the diameter of a graph compared with Gibbs-Poole-Stockmeyer (GPS) algorithm. As the new parameter was implemented in GPS algorithm, a novel bandwidth and profile reduction algorithm is proposed. Simulation results show that with the proposed algorithm bandwidth and profile could be reduced by as great as 33.33% and 11.65%, respectively, compared with the outcomes in GPS algorithm, while the execution time of both algorithms is close. Empirical results show that the proposed algorithm is superior to GPS algorithm in reducing bandwidth or profile.
BANDWIDTH REDUCTION ON SPARSE MATRICES BY INTRODUCING NEW VARIABLES
Glüge,Rainer;
Ingeniare. Revista chilena de ingeniería , 2010, DOI: 10.4067/S0718-33052010000300013
Abstract: a sparse matrix bandwidth reduction method is analyzed. it consists of equation splitting, substitution and introducing new variables, similar to the substructure decomposition in the finite element method (fem). it is especially useful when the bandwidth cannot be reduced by strategically interchanging columns and rows. in such cases, equation splitting and successive reordering can further reduce the bandwidth, at cost of introducing new variables. while the substructure decomposition is carried out before the system matrix is built, the given approach is applied afterwards, independently on the origin of the linear system. it is successfully applied to a sparse matrix, the bandwidth of which cannot be reduced by reordering. for the exemplary fem simulation, an increase of performance of the direct solver is obtaine.
A Bandwidth-Efficient Service for Local Information Dissemination in Sparse to Dense Roadways  [PDF]
Estrella Garcia-Lozano,Celeste Campo,Carlos Garcia-Rubio,Alberto Cortes-Martin,Alicia Rodriguez-Carrion,Patricia Noriega-Vivas
Sensors , 2013, DOI: 10.3390/s130708612
Abstract: Thanks to the research on Vehicular Ad Hoc Networks (VANETs), we will be able to deploy applications on roadways that will contribute to energy efficiency through a better planning of long trips. With this goal in mind, we have designed a gas/charging station advertising system, which takes advantage of the broadcast nature of the network. We have found that reducing the number of total sent packets is important, as it allows for a better use of the available bandwidth. We have designed improvements for a distance-based flooding scheme, so that it can support the advertising application with good results in sparse to dense roadway scenarios.
Exploiting Sparse Dynamics For Bandwidth Reduction In Cooperative Sensing Systems  [PDF]
Harish Ganapathy,Constantine Caramanis,Lei Ying
Mathematics , 2012, DOI: 10.1109/TSP.2013.2260336
Abstract: Recently, there has been a significant interest in developing cooperative sensing systems for certain types of wireless applications. In such systems, a group of sensing nodes periodically collect measurements about the signals being observed in the given geographical region and transmit these measurements to a central node, which in turn processes this information to recover the signals. For example, in cognitive radio networks, the signals of interest are those generated by the primary transmitters and the sensing nodes are the secondary users. In such networks, it is critically important to be able to reliably determine the presence or absence of primary transmitters in order to avoid causing interference. The standard approach to transmit these measurements from sensor the nodes to the fusion center has been to use orthogonal channels. Such an approach quickly places a burden on the control-channel-capacity of the network that would scale linearly in the number of cooperating sensing nodes. In this paper, we show that as long as one condition is satisfied: the dynamics of the observed signals are sparse, i.e., the observed signals do not change their values very rapidly in relation to the time-scale at which the measurements are collected, we can significantly reduce the control bandwidth of the system while achieving the full (linear) bandwidth performance.
Digital Road Profile Using Kinematic GPS
Ashraf Farah
Artificial Satellites , 2009, DOI: 10.2478/v10018-009-0023-6
Abstract: A Digital Road Profile (DRP) is a digital representation of road surface topography or terrain in the longitudinal direction. The need for accurate DRP is vital in two stages; before the road construction starts and after the road construction finished where the verification of its geometrical characteristics is essential for engineering safety purposes. Classical surveying techniques are traditionally used for the DRP generation with limitation of high-cost and time-waste. Kinematic DGPS or Real Time Kinematic DGPS positioning can provide accurate enough results for such application. This paper presents an assessment study of using kinematic GPS technique for DRP generation comparing with classical survey in south Egypt. The results shows that, vehicle-GPS system used in combination with post processing kinematic DGPS gave satisfactory accuracy for nearly all points for a distance of nearly 2 km. with max. and min. difference not more than 7.7 cm, a mean value of 0.10 cm and a Root Mean Square RMS value of 4.11 cm.
Reducing Handover Delay By Pre-Selective Scanning Using GPS  [PDF]
Debabrata Sarddar,Joydeep Banerjee,Jaydeep Ghosh Chowdhury,Ramesh Jana
International Journal of Distributed and Parallel Systems , 2010,
Abstract: IEEE 802.11 based mobile communication towers is used very much in many personal and industrial purposes as it provides a continuous connectivity to Mobile Nodes (MNs) and allows them to change their attachment point from old Access Point (A)P to new AP while needed. But one main problem of continuous connectivity is handover latency which consists of scanning, authentication and re-association phases. Scanning is the most time consuming part of handover process. In this paper, we introduce a prescanning mechanism using Global Positioning System (GPS) to reduce handover delay. In our method, scanning is completed almost before actual handover starts. From the simulation results, it can be seen that our proposed mechanism reduces handover delay by a great deal.
On sparse sensing and sparse sampling of coded signals at sub-Landau rates  [PDF]
Michael Peleg,Shlomo Shamai
Mathematics , 2013,
Abstract: Advances of information-theoretic understanding of sparse sampling of continuous uncoded signals at sampling rates exceeding the Landau rate were reported in recent works. This work examines sparse sampling of coded signals at sub-Landau sampling rates. It is shown that with coded signals the Landau condition may be relaxed and the sampling rate required for signal reconstruction and for support detection can be lower than the effective bandwidth. Equivalently, the number of measurements in the corresponding sparse sensing problem can be smaller than the support size. Tight bounds on information rates and on signal and support detection performance are derived for the Gaussian sparsely sampled channel and for the frequency-sparse channel using the context of state dependent channels. Support detection results are verified by a simulation. When the system is high-dimensional the required SNR is shown to be finite but high and rising with decreasing sampling rate, in some practical applications it can be lowered by reducing the a-priory uncertainty about the support e.g. by concentrating the frequency support into a finite number of subbands.
DEM production for Dome-A combining GPS and GLAS data
结合GPS和GLAS数据生成Dome-A区域DEM

WANG Xianwei,CHENG Xiao,HUANG Huabing,LI Zhan,
王显威
,程晓,黄华兵,李展

遥感学报 , 2013,
Abstract: A method is presented for combining GPS and GLAS data to produce a high-quality DEM. First, the GLAS data was transformed so that it could be combined with GPS data to produce a DEM. An algorithm was selected to locate GLAS points and the GPS points covered by GLAS footprints were highlighted. Comparison of the two types of data indicates that the maximum and minimum mean height differences are 1.118 m and 0.997 m, respectively, with a stable standard of about 5-6 cm. The maximum and minimum values became 0.405 m and 0.284 m after rectification by ellipsoid transformation. Detailed components of the error are also discussed. Next, sparse GPS data were extracted as feature points along the GPS measurement profile using a revised angle limitation method. Finally, a DEM was produced for the Dome-A using processed GPS data and transformed GLAS data. 1199 of the GPS points and 53 of the GLAS footprints were used to validate the DEM, with 5 cm and 12 cm as the mean and absolute maximum, respectively, of residuals. Additionally, three other DEMs were produced using original GPS data, original GPS data and GLAS data, and processed GPS data. The DEM produced with processed GPS data exhibited better accuracy than that produced from original GPS data according to comparison of contours and residuals of check points, confirming the importance of the GPS process.
The profile of general practitioners (GPs) who publish in selected family practice journals
J Soler-González, C Ruiz, C Serna, JR Marsal
BMC Research Notes , 2011, DOI: 10.1186/1756-0500-4-164
Abstract: The authors of all articles published in 2006 and 2007 in three international Family Medicine journals - Annals of Family Medicine, Family Practice, and Journal of Family Practice - were contacted by E-mail. They were asked to complete a questionnaire investigating the following variables: availability of specific time for research, time devoted to research, number of patients attended, and university affiliation. Only GPs were included in the study. Three hundred and ten relevant articles published between 2006 and 2007 were identified and the authors contacted using a survey tool. 124 researchers responded to our questionnaire; 45% of respondents who were not GPs were excluded. On average GPs spent 2.52 days per week and 6.9 hours per day on patient care, seeing 45 patients per week. Seventy-five per cent of GPs had specific time assigned to research, on average 13 hours per week; 79% were affiliated to a university and 69% held teaching positions.Most GPs who publish original articles in leading journals have time specifically assigned to research as part of their normal working schedule. They see a relatively small number of patients. Improving the working conditions of family physicians who intend to investigate is likely to lead to better research results.The promotion of quality research contributes to a successful Primary Care service. However, when family physicians spend most of their time attending patients, their opportunities for conducting research are limited.Research in Primary Care has three positive effects: patients receive improved quality of care; physicians' job satisfaction and motivation increase; and the health system benefits from improved clinical efficacy and effectiveness [1-3].For many years, family physicians have sought to increase funding and to extend the time available for research that would aid public health and university teaching [4]. GPs need answers to clinical questions from studies related to family medicine [5].Several stu
Differentiated Bandwidth Allocation in Mobile Ad Hoc Networks (MANET)-A Profile Based Approach
R. Gunasekaran,V. Rhymend Uthariaraj
Asian Journal of Information Technology , 2012,
Abstract: A major proliferating architecture, that extends its services globally in wireless networks, is Ad Hoc network, which endows more research areas to work with. In next generation networks, user can be accurately determined and maintained by the network on per-user basis. This study investigates the design of Ad Hoc network architecture that exploits user profiles to maximize network efficiency and promote better quality of service by differentiated bandwidth reservation and resource allocation to different classes of users. A model called High-Privileged and Low-Privileged Architecture (HPLP) for the forthcoming Ad Hoc network is proposed through which differentiated services can be achieved for different class of users. A new MAC protocol named as D-MACAW is also suggested for the proposed architecture. Among the various factors influencing the differentiated services, bandwidth reservation is only considered and different factors that can influence the efficiency of the bandwidth reservation are identified. Two classes of users are considered as high-privileged, a high-cost and efficient service users and low-privileged, low-cost and best effort service users. The differentiated service provided for the different classes of users is proved through simulation analysis. The results obtained using ns2 show that efficient quality of service is guaranteed to users who subscribe high-privileged profile.
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