By Topic

This IEEE Publication is an Open Access only journal. Open Access provides unrestricted online access to peer-reviewed journal articles.

Date 5-8 Sept. 2004

Filter Results

Displaying Results 1 - 25 of 3655902
  • System-level benefit of combined power control and multiuser detection for CDMA uplink over a frequency selective channel

    Publication Year: 2004 , Page(s): 2187 - 2191 Vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (728 KB) |  | HTML iconHTML  

    This paper analyzes the benefit of power control and multiuser linear detection for CDMA uplink transmissions. Several papers have recently shown a benefit for such an approach in the case of synchronous uplink transmissions without multipath propagation. We study the impact of a multipath channel on the system level performance. ZF and MMSE multiuser block linear receivers are considered for various scenarios to compare them and to analyze the influence of multipath propagation and of out-cell interference. The results are compared to the performance obtained with a RAKE receiver. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • k-weighted minimum dominating sets for sparse wavelength converters placement under nonuniform traffic

    Publication Year: 2003 , Page(s): 56 - 61
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (306 KB) |  | HTML iconHTML  

    In WDM all-optical networks, the deployment of wavelength converters improves the blocking performance. One solution is to equip every node in the network with converters (full wavelength conversion); however the cost and the technological limitations make it not practical. The alternative is to choose a subset of nodes and equip them with wavelength converters (sparse wavelength conversion). This paper makes the first known attempt to solve the sparse wavelength converters placement problem using the k-weighted minimum dominating set (k-WMDS) approach. To evaluate our proposed scheme under nonuniform traffic, we compared it against the well-known approach (referred to as k-BLK) of placing converters in nodes having the highest blocking percentage. The two algorithms were compared under different nonuniform traffic loads using network simulation with the U.S Long Haul and NSFNET topologies. For different values of the hop-distance parameter, k, the proposed k-WMDS algorithm has consistently given better blocking performance than k-BLK under the constraint that the number of converters in both algorithms is equal to the cardinality of the k-weighted minimum dominating set. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transient analysis of branch-line coupler by using the modified central difference method

    Publication Year: 2004 , Page(s): iii - 351-4 vol.3
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (454 KB) |  | HTML iconHTML  

    In this paper we present an approach to the transient analysis of a branch-line coupler by using the modified central difference (MCD) method with the signal flow graph boundary treatment for the line discontinuities. Multiple reflections on the transmission lines with T-junctions are demonstrated for a step and sinusoidal wave excitations. Additionally, the frequency response is also obtained from the pulse responses of the simulated results. Some examples are presented to illustrate the validity of the proposed method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A 90-GHz InP-HEMT lossy match amplifier with a 20-dB gain using a broadband matching technique

    Publication Year: 2004 , Page(s): 145 - 148
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (579 KB) |  | HTML iconHTML  

    We demonstrated a 90-GHz InP-HEMT lossy match amplifier (LMA) with a 20-dB gain for the first time. We obtained this performance with the power consumption of 220 mW, which is the smallest one ever reported for an over 80-GHz broadband amplifier. The amplifier acts as a C-R coupled amplifier in the low to medium frequency range and as an L-C match amplifier at the high frequencies. Therefore, this configuration provides both high gain and wide bandwidth. The key to achieve a 90-GHz bandwidth is broadband matching in the L-C match amplifier. In this paper, we propose a broadband matching technique with a low Q network and describe the design guideline for the excellent performance. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reed-Muller universal logic module networks

    Publication Year: 1993 , Page(s): 105 - 108
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (220 KB)  

    Describes Reed-Muller universal logic modules (RM-ULMs) and their use for the implementation of logic functions given in Reed-Muller (RM) form. A programmed algorithm is presented for the synthesis and optimisation of RM-ULM networks. The level-by-level minimisation procedure is based on the selection of control variables at different levels with the aim of maximising the number of discontinued branches and hence minimising the number of modules required to implement a given function. The algorithm is programmed in Fortran and can be used to realise fixed-polarity generalised Reed-Muller (GRM) expansions of any polarity and any number of variables. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Transmission power control in wireless ad hoc networks: challenges, solutions and open issues

    Publication Year: 2004 , Page(s): 8 - 14
    Cited by:  Papers (73)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (279 KB) |  | HTML iconHTML  

    Recently, power control in mobile ad hoc networks has been the focus of extensive research. Its main objectives are to reduce the total energy consumed in packet delivery and/or increase network throughput by increasing the channel's spatial reuse. In this article, we give an overview of various power control approaches that have been proposed in the literature. We discuss the factors that influence the selection of the transmission power, including the important interplay between the routing (network) and the medium access control (MAC) layers. Protocols that account for such interplay are presented. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Unified approach for masses and microcalcifications detection in mammograms

    Publication Year: 2004 , Page(s): 329 - 330
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (324 KB) |  | HTML iconHTML  

    Mammography is the most effective method for the detection of early breast cancer. However, many studies showed that radiologists, even the experienced ones, couldn't detect all breast cancer that appears on the mammograms. Thus, computer-assisted diagnosis (CAD), based on advanced image processing and pattern recognition techniques, is used to locate and classify possible lesions. In this paper, we present a general approach for the lesions detection in mammograms. This approach performs the detection in the both cases of masses and microcalcifications. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Distribution of slanted write field for perpendicular recording heads with shielded pole

    Publication Year: 2005 , Page(s): 579 - 580
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (61 KB) |  | HTML iconHTML  

    In this paper, the write field distribution for the perpendicular writer with and without shielded pole is investigated using 2D and 3D finite element methods (FEM). The slanted write fields due to shielded pole at the trailing edge and the leading edge of the main pole tip and the influence of the design parameters are analyzed in details. The analysis shows that the use of the shielded pole leads to change in the saturation levels in the main pole tip. As such, careful design is necessary to achieve optimal distribution of the slant field and maximum possible field amplitude that is limited by the saturation induction of the soft-magnet material of the pole tip. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Xenon discharge produced plasma radiation source for EUV lithography

    Publication Year: 2005 , Page(s): 2320 - 2323 Vol. 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (369 KB) |  | HTML iconHTML  

    EUV radiation with wavelengths of 11 to 14 nm is seen as the most promising candidate for a new lithographic technology. Compared to synchrotron radiation sources and laser produced plasmas, gas discharge produced plasma (GDP) sources for EUV radiation are expected to offer lower cost of ownership. Using xenon a broadband emission in the investigated wavelength range from 10 to 18 nm is observed. Very short current pulses, having a fast rise time with 85 ns or 140 ns duration and 20 kA amplitude, were applied across the xenon-filled z-pinch capillary (3 mm diameter and 5 mm length) to produce EUV radiation. A EUV radiation from the z-pinch plasma was characterized, which is based on the temporal behavior of EUV intensity and the pinhole images. Two maximum EUV radiations occur, which are sensitive to the xenon flow rate and the discharge current. The 1st radiation is relatively short duration while the 2nd radiation lasts as long as the 1st period of the current flows. EUV source size due to the 1st radiation is approximately 300 μm that is half of one due to the 2nd radiation. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimise the dynamic range of a sigma-delta modulator

    Publication Year: 2004 , Page(s): iii - 375-8 vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (382 KB) |  | HTML iconHTML  

    This paper introduces analytic and numerical methods to optimise the dynamic range of a third-order sigma-delta analogue-to-digital converter (ADC). Quantisation noise in a specified bandwidth is predicted and expressed relative to the maximum sinusoidal output from the ADC, for a range of design parameters, in order to establish the optimum design to achieve maximum dynamic range. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Implementation of CMRC on HBT power amplifier for WCDMA application

    Publication Year: 2004 , Page(s): 2242 - 2245 vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (141 KB) |  | HTML iconHTML  

    An InGaP/GaAs heterojunction bipolar transistor (HBT) is developed. By using this HBT, a power amplifier is designed for WCDMA user equipment, band-1 power class-2 application. The HBT power amplifier demonstrates a maximum output power (Pout) of 29.4 dBm and a PAE of 48% at the frequency of 1.95 GHz. When it operates in the WCDMA standard, it achieves a Pout of 27 dBm and a PAE of 32.4%. The adjacent channel leakage power ratio (ACLR) is -33 dBc. To improve the PAE, ACLR and IM3 performance further, a CMRC (compact microstrip resonance cell) circuit has been implemented on the HBT amplifier. The effect of CMRC on PAE and ACLR is investigated using a low power HBT amplifier. The results show that the ACLR can be improved by the CMRC. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A framework for applying inventory control to capacity management for utility computing

    Publication Year: 2005 , Page(s): 237 - 250
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (181 KB) |  | HTML iconHTML  

    A key concern in utility computing is managing capacity so that application service providers (ASPs) and computing utilities (CUs) operate in a cost effective way. To this end, we propose a framework for applying inventory control to capacity management for utility computing. The framework consists of: conceptual foundations (e.g., establishing connections between concepts in utility computing and those in inventory control); problem formulations (e.g., what factors should be considered and how they affect computational complexity); and quality of service (QoS) forecasting, which is predicting the future effect on QoS of ASP and CU actions taken in the current period (a critical consideration in searching the space of possible solutions). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Network information content security: a framework for intelligent analysis and monitoring

    Publication Year: 2005 , Page(s): 841 - 843 Vol. 2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB) |  | HTML iconHTML  

    The security assurance of network is critical to the whole modern world. As the increasingly occurred common network security incidents, current network security approaches are not sufficient. To transcend these limits, we should synthetically analyze security related factors from various kinds of sources and visual perspectives. Therefore we present a general framework for intelligent analysis and monitoring the security of network information content in high-speed network. The system can intelligently gather and transform various channels of non-structured, semi-structured and structured data based on broadband network; carry on security assurance related characteristic selections and topic identification; perform social network analysis of email and BBS; and fuse analysis of technical, social, economic and political triggers to information security incidents. The system can help information security experts find the association rules in the results from various analyzing levels, and visualize association patterns by their relational structures from link analysis techniques and provide early warning to system administrators. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Mode-filtering characteristics of hard-polymer cladding fiber

    Publication Year: 2003 , Page(s): 15 - 16 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (313 KB) |  | HTML iconHTML  

    Bandwidth improvement due to the mode-filtering effect caused by mode-dependent loss mechanism in a hard-polymer cladding fiber was investigated experimentally as well as numerically. We believe this principle can be applied to silica and plastic multimode fibers. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Value of storage devices in congestion constrained distribution networks

    Publication Year: 2004 , Page(s): 624 - 629 Vol.1
    Cited by:  Papers (6)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (334 KB) |  | HTML iconHTML  

    This paper investigates the value of storage devices in congestion constrained distribution networks. Subject of the investigations is a load, which cannot be supplied with the desired security at all times during the day. It is analyzed what the requirements would be if a storage device would be installed at the load bus instead of network reinforcement. To compare these two possible solutions, the implications on the load flow, including loss reduction and the possibility of local voltage control, are investigated. Furthermore the availability of a system with three lines is used to determine failure and repair rate requirements for a storage device. Finally some general economical considerations are outlined. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Addressing the electronic bottleneck to virtual topology design of optical networks

    Publication Year: 2003 , Page(s): 925 - 930 vol.2
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (431 KB) |  | HTML iconHTML  

    The virtual topology design of optical networks is generally formulated as an optimization problem with the objective of attain the minimum congestion on the traffic load of the lightpaths. However, the data transmission capacity of the networks is not being limited by the optical layer any more. Nowadays, the electronic data processing capacity of the nodes, the so-called electronic bottleneck, is the most severe limitation to the traffic transmission rate growth of high-speed optical networks, due to the great development of the optical layer resources in the past years. This work presents a novel formulation to design virtual topologies of optical networks that minimizes the electronic data processing in the networks nodes, focusing the optimization objective on node congestion, (electronic data processing) instead of on lightpath congestion (optical data transmission). A comparison between the former congestion minimization formulation and the new one proposed in this work is done, analyzing the impact on congestion and the electronic data processing distribution among the network nodes. A significant reduction in the processing time of the proposed mixed-integer optimization problem is also reported. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A dynamic probabilistic multimedia retrieval model

    Publication Year: 2004 , Page(s): 1607 - 1610 Vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (702 KB) |  | HTML iconHTML  

    We describe the application of a probabilistic multimedia model to video retrieval. From video shots, we compute Gaussian-mixture models that capture correlations in time and space, such as the appearance and disappearance of objects. These models improve the precision of "query by example/s" results in the TRECVID 2003 collection when compared to models that only make use of static visual information. Furthermore, integrated with information from automatic speech recognition (ASR) transcripts, they outperform ASR only results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Neural network identification and performance assessment of a multipath time-varying satellite channel

    Publication Year: 2005 , Page(s): 2221 - 2225
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (282 KB) |  | HTML iconHTML  

    First Page of the Article
    View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Development of a hybrid CVD/SOD integration sequence for reliable, high performance interconnect systems

    Publication Year: 2004 , Page(s): 433 - 436
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (359 KB) |  | HTML iconHTML  

    The use of hybrid integration schemes is investigated using a combination of a SiOC film at the via level and a porous SiLK Y film at the trench level. Sequential finite element analysis is used to determine the mechanics and, subsequently, a hybrid damascene interconnect is built to demonstrate the approach. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Prototype of a stochastic optimal control based approach to incident-responsive coordinated ramp control

    Publication Year: 2004 , Page(s): 255 - 260 Vol.1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1562 KB)  

    This paper presents a real-time coordinated ramp control approach in response to incident-induced traffic congestion on freeways. The proposed control methodology includes two major functions to alleviate in real time incident impact on multi-segment traffic flows of freeways, i.e. (1) identification of control zone-based congestion patterns, and (2) stochastic optimization of group-based ramp metering control. To reduce congestion, the modified generalized sequential probability ratio testing (M-GSPRT) technology together with stochastic optimal control methods are used, respectively, in the above two mechanisms. With the aid of the Paramics microscopic traffic simulator, numerical results obtained under various simulated incident-induced congestion conditions indicate the feasibility of the proposed method. Numerical test results indicate both the feasibility of the proposed ramp control method in responding to diverse lane-blocking incident conditions, and its efficiency, particularly in improving the averaged hourly throughput by 67.5% in medium-volume incident cases, compared with the no-control strategy. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ocean winds retrieved from X-band radar-image sequences

    Publication Year: 2003 , Page(s): 1261 - 1263 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2912 KB) |  | HTML iconHTML  

    A new method for retrieving wind speeds and directions using nautical radar-image sequences is presented. The method consists of two parts, one for wind direction and another for wind speed retrieval. Wind directions are locally extracted from wind induced streaks, which are approximately in line with the mean wind direction. The algorithm assumes wind direction as normal to the local gradients of the amplitude image. Wind speeds are derived from the radar cross section, by parameterization of its dependency on the wind vector, which is performed by training of a neural network. For verification of the method the wind direction and speed from nearly 1400 radar-image sequences are compared to in situ data from a wind sensor. The accuracy and limitations of the method are discussed. A second new method is introduced, which enables to retrieve spatial and temporal wind fields from radar-image sequences. Thereby the wind streaks are available in space and time. The local velocity and direction of the wind pattern of each point in the investigated area is determined using tensor-based techniques. This method has the advantage that no calibration of the radar images or training of a neural network is necessary. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • An analytical model for user satisfaction in WCDMA systems based on the ETSI criteria

    Publication Year: 2003 , Page(s): 382 - 386 vol.1
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB) |  | HTML iconHTML  

    Most analytical models for the evaluation of convergence and capacity of WCDMA systems aim at evaluating only the outage probability of a given cellular deployment scenario. This is not in line with the ETSI guidelines for performance evaluation, which state that the coverage and the capacity of the system should be measured in terms of a given percentage of unsatisfied users. In this paper, we elaborate an analytical model capable of giving such a figure. In addition, a comparison between analytical and simulation results confirms the validity of the proposed model. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A step forward in manual welding: demonstration of augmented reality helmet

    Publication Year: 2003 , Page(s): 309 - 310
    Cited by:  Papers (7)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1745 KB) |  | HTML iconHTML  

    A new welding helmet for the manual welding process has been developed. The welders working conditions are improved by augmenting the visual information before and during welding. The image is improved by providing a better view of the working area. An online quality assistant is available during welding, suggesting the correction of the guns position or pointing out welding errors, by analyzing the electrical welding parameters. An assembly advisor will suggest the assembly sequence, by displaying the type and the position of the following piece into the actual ensemble. In addition, an available online documentation of the welding process gives an opportunity to reduce the effort of post process quality assurance which often uses expensive X-ray investigations. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Coronographic results and myocardiac scintigraphy data relationship: towards coronary artery disease prognosis

    Publication Year: 2004 , Page(s): 333 - 334
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (288 KB) |  | HTML iconHTML  

    In this paper, we define the relationship between the location and the degree of the stenosis in coronary arteries and the observed perfusion on the myocardiac scintigraphy. This allows us to model the impact evolution of these stenoses in order to justify a coronarography or to avoid it for patients suspected being in the gray zone. Our approach is decomposed in two steps. The first step consists in modelling a coronary artery bed and stenoses of different location and degree. The second step consists in evaluating the badly perfused volume using only myocardial scintigraphic data. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • A branch-based method to break-point determination for coordination of over-current and distance relays

    Publication Year: 2004 , Page(s): 1857 - 1862 Vol.2
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (272 KB) |  | HTML iconHTML  

    Modern power systems have a multiloop structure. Coordination of distance and over-current relays in these networks is a tedious and time consuming task. The most complicated part of this problem is determination of break-point set (BPS) to start relays setting. As BPS is not unique, it is desirable to determine a BPS with a minimum or near to minimum number of members. This paper presents a new BPS determination method based on the network branches. Two lemmas are presented to simplify the network. Application of these lemmas splits the network into some reduced subnetworks, if possible. This reduces the problem dimension and computational burden. This method is so simple it even can be applied on a network manually. Moreover, this method has the capability of considering the three-end branches such as three-terminal transmission lines and three-winding transformers, which graph theory based methods can not handle these cases. The validity of the new method has been tested for an Iranian network. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.