ppxscal/embedding_network huggingface dataset:
Uncoordinated orthogonal frequency division multiple access: to spread or not to spread
Authors: Harish Viswanathan
Venue: IEEE Transactions on Wireless Communications (2009)

We study uncoordinated multiple access using the orthogonal frequency division multiple access (OFDMA) technique where multiple users independently and randomly pick a sub-carrier from a set of sub-carriers for transmission in each slot. Signals transmitted on distinct sub-carriers are orthogonal to each other while signals transmitted by different users on the same sub-carrier interfere with each other. We study average throughput and outage probability performance of such a system in the asymptotic limit of large numbers of sub-carriers and users while keeping the ratio of number of users to sub-carriers fixed, for non-fading, flat fading, and frequency-selective fading additive white Gaussian noise channels. The performance is compared to that of a system in which all users spread their signal over all the sub-carriers as in a code division multiple access (CDMA) system. Our results show that at high signal-to-noise ratio (SNR), transmission without spreading results in higher throughput but requires more retransmissions on the average. At low SNRs, the throughput performance is comparable but the system with spreading requires smaller average number of retransmissions.
Hands-On Remote Labs: Collaborative Web Laboratories as a Case Study for IT Engineering Classes
Authors: Antonella Longo, Mario Bochicchio
Venue: IEEE Transactions on Learning Technologies (2009)

The development of a reusable collaborative software framework for the remote control of a large range of laboratory equipments is an interesting topic to teach information technologies in an engineering school. The design and implementation of this kind of framework, in fact, requires the ability to integrate skills about software engineering, computer networks, human-computer interaction, distributed architectures, and remote control of hardware devices (i.e., laboratory equipments). In the paper, we describe our experience in the development of a reusable framework for remote laboratories, which has been adopted as a case study in two different scenarios at our university.
A method of workload compression basing on characteristics for index selection
Authors: Xin Zhang, Zhihao Zhang, Jinlong Lin
Venue: Proceeding of the ACM first international workshop on Data-intensive software management and mining (2009)

This paper presents a novel method of database workload compression basing on the queries' characteristics for purpose of solving Index Selection Problem (ISP). The algorithm applies a close analysis on the queries in workload to capture their characteristics, which are used to build the relationships between pairs of queries. Using these relationships, the original workload can be filtered out into the compressed workload, which can be used for the task without degrading the performance. This method has been implemented and the experiments on workloads illustrate that proposed solution can achieve a high performance with a little quality loss.
Linear beamforming and superposition coding with common information for the Gaussian MIMO broadcast channel
Authors: Hieu T. Do, Sae-Young Chung
Venue: IEEE Transactions on Communications (2009)

A Gaussian multiple-input multiple-output broadcast channel (MIMO GBC) is considered. Throughout the paper it is assumed that 1) input signals are Gaussian and 2) perfect channel state information is available at the transmitter and at the receivers. By considering each data stream as a single user, the uplink-downlink signal-to-interference-plus-noise (SINR) duality is generalized to the MIMO case with general cross-talk matrix. The duality is subsequently applied to finding the solution for the SINR-balancing problem. The result serves as a tool for characterizing achievable rate regions of different coding strategies. Next, we investigate a superposition coding scheme proposed by Cover-van der Meulen-Hajek and Pursley (nicknamed CMHP [1]), where there is a common message to both users. We consider a MIMO broadcast channel with two users, each user has two antennas and the transmitter has four antennas. Assuming one common stream is sent by CMHP coding and successive decoding, a lower bound to the CMHP rate region is found. Behaviors of the CMHP rate region and sumrate are analyzed. We find the sumrate gaps between DPC, CMHP, and MMSE at high SNR for general 2-user multiple-input single-output (MISO) Gaussian broadcast channel. The result suggests when CMHP is beneficial for sumrate.
Identical-capacity channel decomposition for design of universal LDPC codes
Authors: Ali Sanaei, Mahdi Ramezani, Masoud Ardakani
Venue: IEEE Transactions on Communications (2009)

Design of low-density parity-check (LDPC) codes suitable for all channels which exhibit a given capacity C is investigated. Such codes are referred to as universal LDPC codes. First, based on numerous observations, a conjecture is put forth that a code working on N equal-capacity channels, also works on any convex combination of these N channels. As a supporting evidence, we prove that a code satisfying the stability condition on N channels, also satisfies the stability condition on the convex hull of these N channels. Then, a channel decomposition method is suggested which spans any given channel with capacity C in terms of a number of identical-capacity basis channels. We expect codes that work on the basis channels to be suitable for any convex combination of the bases, i.e., all channels with capacity C. Such codes are found over a wide range of rates. An upper bound on the achievable rate of universal LDPC codes is suggested. Through examples, it is shown that our codes achieve rates extremely close to this upper bound. In comparison with existing LDPC codes designed for a given channel, significant performance gain is reported when codes are used over various channels of equal capacity.
Improving cell broadcasting scheme to support multi-lingual service in wireless networks
Authors: Yi Zhu, Xiaofeng Gao, James K. Willson, Changcun Ma, Jason P. Jue, Weili Wu
Venue: IEEE Communications Letters (2009)

In this paper we propose a new problem named energy-efficient multi-lingual cell broadcasting(EEML-CB) to support multi-lingual service in cell broadcasting system. We prove that the problem is NP-hard and then propose ILP model as well as a greedy algorithm named smart multi-lingual cell broadcasting (SMCB). We evaluated our heuristic by simulations.
Efficient scanning algorithm for integrated mobile and nomadic systems: a hierarchical approach
Authors: Jung-Min Moon, Dong-Ho Cho
Venue: IEEE Communications Letters (2009)

We consider a wireless communication environment in which a large number of local area cells are deployed within the coverage of wide area cells. In this environment, a scanning operation to detect a suitable local area cell for handoff can degrade the performance of a mobile station, because repeated scanning trials are likely to cause disruption of service and require considerable consumption of power. Therefore, we propose and analyze a hierarchical scanning algorithm that is capable of providing MS-specific neighbor cell information. Simulation results show that the proposed algorithm can significantly reduce the number of scanning trials required to detect a suitable local area cell for handoff.
Short-Term Power Load Forecasting Using Least Squares Support Vector Machines(LS-SVM)
Authors: Junfang Wu, Dongxiao Niu
Venue: Proceedings of the 2009 Second International Workshop on Computer Science and Engineering - Volume 01 (2009)

Accurate forecasting of electricity load has been one of the most important issues in the electricity industry. Modern data mining methods have played a crucial role in forecasting electricity load. Support vector machines (SVMs) have been successfully employed to solve nonlinear regression and time series problems. Based on the Nyström approximation and the primal-dual formulation of the Least Squares Support Vector Machines (LS-SVM), it becomes possible to apply a nonlinear model to a large scale regression problem. With an active selection of support vectors based on quadratic Renyi entropy criteria, approximation of the nonlinear mapping induced by the kernel matrix. The methodology is applied to the case of load forecasting in Inner Mongolia of China.
An internally coded TH/OCDMA scheme for fiber optic communication systems and its performance analysis-Part II: using frame time hopping code
Authors: Mahdi Karimi, M. Nasiri-Kenari
Venue: IEEE Transactions on Communications (2009)

In Part I, a new internally coded time hoping optical code division multiple access (TH/OCDMA) scheme for fiber optic communication systems has been proposed and its multiple access performance has been evaluated using optical orthogonal code (OOC). Due to low cardinality of OOCs with a correlation value of 1, the capability of the proposed scheme could not be utilized effectively for an increasing number of simultaneous users. In this part, we consider applying the internally coded technique introduced in part one to the frame time hopping/OCDMA scheme. We evaluate the multiple access performance of the system for the three detectors introduced in Part I. Our results demonstrate the capability of the internally coded TH/CDMA scheme to substantially increase the maximum number of simultaneous users when using FTH codes instead of OOCs.
Guest Editors' Introduction: Strategic Planning in Today's IT Environment
Authors: Frank E. Ferrante, G. Reza Djavanshir, Tom Costello
Venue: IT Professional (2009)

This introduction to the special issue dedicated to strategic planning presents the complexity and dynamics of global enterprise IT management in today's tight and unstable economic environment. IT managers and enterprise executives can achieve their overall business success by opening channels of communications among their normally independent organizational silos and by creating an enterprise-shared culture that recognizes the critical role IT has in this endeavor.
Extracting problem solved concepts from patent documents
Authors: Shahzad Tiwana, Ellis Horowitz
Venue: Proceeding of the 2nd international workshop on Patent information retrieval (2009)

In this paper, we report the results for the experiments we carried out to automatically extract "problem solved concepts" from a patent document. We introduce two approaches for finding important information in a patent document. The main focus of our work is to devise methods that can efficiently find the problems an invention solves, as this can help in searching for the prior art and can be used as a mechanism for relevance feedback. We have used software and business process patents to carry out our studies.
Simulation Soft System on the Fatigue Life Loss of Startup and Shutdown for a 600MW Steam Turbo Unit
Authors: Yunchun Xia
Venue: Proceedings of the 2009 Second International Workshop on Computer Science and Engineering - Volume 02 (2009)

The simulation system on the thermal stress & fatigue life loss of the rotor during startup & shutdown for a domestic 600MW steam turbo generator unit, by the simulation, the surface of the shaft was suffered a crushing stress, but it was a pulling stress when a unit shutdown. The max thermal stress & the max combined stress produced on the rotor of a medium pressure cylinder was about 17.6% bigger than those on the rotor of the high pressure cylinder when they had the same increase rate of temperature. When thought from economics & safety, the optimal temperature-increase-rate of the rotor was 2.05℃℃/min when the unit startup at hot state, and shut down the unit, it’s optimal for slipping-parameter and the optimal temperature-decease-rate of the rotor was 0.78℃/min.
Virtual Teams and the Importance of Building Trust
Authors: Georgina Harell, Tugrul U. Daim
Venue: IT Professional (2009)

Trust in the workplace is both an ethical and a management issue. Virtual teams have become common in IT, but the importance of building trust in such teams is often underappreciated. In this installment of IT Ethics, the authors look at several definitions and theories of trust and their application in virtual IT teams.
Hierarchical Conflict Detection for Cluster's Transactional Memory
Authors: Ruibo Wang, Kai Lu
Venue: Proceedings of the 2009 Fifth International Joint Conference on INC, IMS and IDC (2009)

Transactional Memory (TM) research has focused on multi-core processors; limited research has been aimed at the clusters. The intention of deploying TM on clusters is using more processors to solve big problems with this convenient technique. But the performance of the existing cluster’s TM is poor because of the expensive remote access. The conflict detection, which is the most frequent operation of TM, is highly depending on the remote memory access. The remote memory access is usually 10 to 100 times slower than the local one in a cluster. We introduce a hierarchical conflict detection strategy. By dividing the conflict detection process into two levels, the hierarchical strategy provides a good practical performance.
An average velocity-based routing protocol with low end-to-end delay for wireless sensor networks
Authors: Sung-Chan Choi, Seong-Lyong Gong, Jang-Won Lee
Venue: IEEE Communications Letters (2009)

To reduce energy consumption, in most MAC protocols for wireless sensor networks, listen-sleep cycles are adopted. However, even though it is a good solution for energy efficiency, it may introduce a large end-to-end delay due to sleep delay, since a node with a packet to transmit should wait until the next-hop node of the packet awakes. To resolve this issue, in this paper, we propose the Average Velocity-Based Routing (AVR) protocol for wireless sensor networks that aims at reducing the end-to-end delay. The AVR protocol is a kind of a geographic routing protocol that considers both location of a node and waiting time of a packet at the MAC layer. When a node can use information of n-hop away neighbor nodes, it calculates the n-hop average velocity for each of its one-hop neighbor nodes and forwards a packet to the neighbor node that has the highest n-hop average velocity. Simulation results show that as the knowledge range, n, increases, the average end-to-end delay decreases.
Spatial correlation of alien crosstalk in MIMO DSL systems
Authors: Leif Sandstrom, Kevin W. Schneider, Laurie L. Joiner, Arlynn Wilson
Venue: IEEE Transactions on Communications (2009)

We statistically characterize the spatial correlation of measured far-end crosstalk collected on 2 kft of 26 AWG twisted-pair copper cable. We then develop and verify a parameterized model of this spatial correlation and use it to investigate the behavior of the spatial correlation of far-end crosstalk in a twisted-pair environment.
A geo-spatial data management system for potentially active volcanoes-GEOWARN project
Authors: Radu C. Gogu, Volker J. Dietrich, Bernhard Jenny, Florian M. Schwandner, Lorenz Hurni
Venue: Computers Geosciences (2006)

Integrated studies of active volcanic systems for the purpose of long-term monitoring and forecast and short-term eruption prediction require large numbers of data-sets from various disciplines. A modern database concept has been developed for managing and analyzing multi-disciplinary volcanological data-sets. The GEOWARN project (choosing the ''Kos-Yali-Nisyros-Tilos volcanic field, Greece'' and the ''Campi Flegrei, Italy'' as test sites) is oriented toward potentially active volcanoes situated in regions of high geodynamic unrest. This article describes the volcanological database of the spatial and temporal data acquired within the GEOWARN project. As a first step, a spatial database embedded in a Geographic Information System (GIS) environment was created. Digital data of different spatial resolution, and time-series data collected at different intervals or periods, were unified in a common, four-dimensional representation of space and time. The database scheme comprises various information layers containing geographic data (e.g. seafloor and land digital elevation model, satellite imagery, anthropogenic structures, land-use), geophysical data (e.g. from active and passive seismicity, gravity, tomography, SAR interferometry, thermal imagery, differential GPS), geological data (e.g. lithology, structural geology, oceanography), and geochemical data (e.g. from hydrothermal fluid chemistry and diffuse degassing features). As a second step based on the presented database, spatial data analysis has been performed using custom-programmed interfaces that execute query scripts resulting in a graphical visualization of data. These query tools were designed and compiled following scenarios of known ''behavior'' patterns of dormant volcanoes and first candidate signs of potential unrest. The spatial database and query approach is intended to facilitate scientific research on volcanic processes and phenomena, and volcanic surveillance.
The effect of different presentation strategies with educational software
Authors: Haya Shamir, Sam Vanous
Venue: Proceedings of the 10th IASTED International Conference on Computers and Advanced Technology in Education (2007)

This study examined the effects that presenting material in various methods using a computer had on children's reading skills. There were 185 preschool children who participated in one of four groups: mastery sequencer, adaptive sequencer, picture menu, and control. Children were pretested and posttested to determine which method of presentation was the most efficient. Gains were calculated for a variety of skills, including initial sound, letter naming, segmenting, and reading nonsense words. It was found that the children utilizing the mastery sequencer had the largest gains overall compared to any of the other three groups. This study emphasizes the importance of how material is presented using a computer. The content is not the only important aspect; how content is relayed to children has significant impact on their learning.
Extraction of sources of tremor in hand movements of patients with movement disorders
Authors: Ramana Vinjamuri, Donald J. Crammond, Douglas Kondziolka, Heung-No Lee, Zhi-Hong Mao
Venue: IEEE Transactions on Information Technology in Biomedicine (2009)

This paper proposes an efficient method to acquire sources of tremor in patients with movement disorders based on blind source separation of convolutive mixtures. The extracted sources indicated neural activities that might be generated in the central nervous system. Four patients with essential tremor were tested in a set of movement tasks. Subjects wore a data glove that measured finger movements of the hand. The experimental data were then fed to a convolutive-mixture model, which revealed sources that imbibed in them the tremor frequency components of 2-8 Hz. Time-frequency analysis of these sources might be of potential help to clinicians to devise tasks that can manifest visible tremor from patients.
A simplified approach for modelling and simulation of network reconfiguration in radial distribution systems
Authors: K. Prasad, N. C. Sahoo
Venue: Proceedings of the IASTED Asian Conference on Modelling and Simulation (2007)

In radial distribution system (RDS), network reconfiguration is frequently performed for optimizing system performance. Before the actual reconfiguration operation is physically performed, it is necessary to have computer-aided performance assessment of the reconfigured RDS from load flow analysis. The purpose of this paper is to clearly and illustratively explain the various underlying sub-processes involved in the simulation experiment of RDS reconfiguration.
Selective Encryption for G.729 Speech Using Chaotic Maps
Authors: Zhaopin Su, Jianguo Jiang, Shiguo Lian, Donghui Hu, Changyong Liang, Guofu Zhang
Venue: Proceedings of the 2009 International Conference on Multimedia Information Networking and Security - Volume 01 (2009)

Speech encryption is becoming increasingly important as the increasing relevance of multimedia applications such as video conference and news broadcasting. However, multimedia encryption and decryption are often computationally demanding and unpractical for power-constrained devices and narrow bandwidth environments. To tackle this situation, two novel selective encryption schemes are presented for G.729 speech in this paper. In the proposed schemes, speech bitstreams are partitioned into two parts based on bit sensitivity, i.e., one is encrypted by a high degree of encryption, and the other is encrypted by a lesser degree. To test the schemes, we introduce two chaotic maps, i.e., cat map and logistic map, and give contrast experiments addressed in signal inspection and objective distortion measure. Additionally, we discuss the two schemes' cryptanalysis and computational complexity. The results demonstrate the effectiveness of our selective encryption schemes for power-constrained devices and narrow bandwidth environments.
Assessment of a stochastic interpolation based parameter sampling scheme for efficient uncertainty analyses of hydrologic models
Authors: Faisal Hossain, Emmanouil N. Anagnostou
Venue: Computers Geosciences (2005)

This study assesses a stochastic interpolation based parameter sampling scheme for efficient uncertainty analyses of stream flow prediction by hydrologic models. The sampling scheme is evaluated within the generalised likelihood uncertainty estimation (GLUE; Beven and Binley, 1992) methodology. A primary limitation in using the GLUE method as an uncertainty tool is the prohibitive computational burden imposed by uniform random sampling of the model's parameter distributions. Sampling is improved in the proposed scheme by stochastic modeling of the parameters' response surface that recognizes the inherent non-linear parameter interactions. Uncertainty in discharge prediction (model output) is approximated through a Hermite polynomial chaos approximation of normal random variables that represent the model's parameter (model input) uncertainty. The unknown coefficients of the approximated polynomial are calculated using limited number of model simulation runs. The calibrated Hermite polynomial is then used as a fast-running proxy to the slower-running hydrologic model to predict the degree of representativeness of a randomly sampled model parameter set. An evaluation of the scheme's improvement in sampling is made over a medium-sized watershed in Italy using the TOPMODEL (Beven and Kirkby, 1979). Even for a very high (8) dimensional parameter uncertainty domain the scheme was consistently able to reduce computational burden of uniform sampling for GLUE by at least 15-25%. It was also found to have significantly higher degree of consistency in sampling accuracy than the nearest neighborhood sampling method. The GLUE based on the proposed sampling scheme preserved the essential features of the uncertainty structure in discharge simulation. The scheme demonstrates the potential for increasing efficiency of GLUE uncertainty estimation for rainfall-runoff models as it does not impose any additional structural or distributional assumptions.
GT cells design and implementation in a glass mould production system
Authors: M. Bulent Durmusoglu, Affan Nomak
Venue: Computers and Industrial Engineering (2005)

Cellular production is maintained to be a popular manufacturing and management philosophy, which is increasingly interested and intensified. In this study, group technology cells design and implementation project in a real life glass mould production system is described. All the stages of the project, the difficulties encountered, the strategies developed that overcome these difficulties and the performance improvements after the implementation of cellular production are explained in detail.