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Issue 2 • Date Mar 1989

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Displaying Results 1 - 25 of 3886032
  • Characteristics of high-transmission-probability tunnel junctions for use as particle detectors

    Page(s): 1343 - 1346
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    Interest in the problem of the galactic dark matter has stimulated development of particle detectors sensitive to very low energies. The authors describe superconducting tunnel junctions with thin barriers which may be suitable for this purpose. They present I-V (current-voltage) characteristics and data on the temperature dependence of the subgap tunneling current. They examine the barrier transmission probability and the resistance of the null junction. They also present some scanning-electron-microscope observations of the thin films of the tunnel junctions, which show that faster deposition produces smaller grains and increasing film thickness results in larger grains from an apparent fusing of smaller grains View full abstract»

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  • A Hexagonal Coverage LED-ID Indoor Positioning Based on TDOA with Extended Kalman Filter

    Page(s): 742 - 747
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (220 KB) |  | HTML iconHTML  

    In this paper we propose a positioning approach based on the time different of arrival (TDOA) algorithm from light emitting diodes to localize mobile targets in indoor environments. The hexagonal lattice alignment of LED transmitters is proposed to reduce the coverage holes and the areas of overlapping radiation. The accuracy of the position estimation is compared to the one in a typical rectangular grid alignment. In addition, an extended Kalman filter is adopted together with the TDOA method to enhance the position estimation performance. View full abstract»

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  • Geminate electron-hole recombination in organic solids in the presence of a donor-acceptor heterojunction

    Page(s): 162102 - 162102-3
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    Geminate electron-hole recombination is one of the main factors limiting the efficiency of organic solar cells. We present a systematic study of this process based on both analytical and simulation models. We determine how the charge-pair separation probability is affected by the hopping length of charge carriers, the presence of a donor-acceptor heterojunction, electron and hole mobilities, and other factors. We show that the charge-pair separation probability of an electron and a hole which are initially at the contact distance is maximized when the electron and hole mobilities are equal to each other. View full abstract»

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  • Resistive mixers for reconfigurable wireless front-ends

    Page(s): 513 - 516
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (210 KB) |  | HTML iconHTML  

    Two resistive mixers realized in a 0.13 μm CMOS process are presented. The mixers are designed for implementation in a reconfigurable mobile terminal that supports the WCDMA mobile phone standard and the IEEE 802.11a and HIPERLAN/2 WLAN standards, respectively. The mixer design process, as well as simulated and measured results, are given and discussed. The entirety of properties and performance makes these mixer types very attractive for reconfigurable architectures. View full abstract»

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  • Phonon-mediated detection of X-rays in silicon crystals using superconducting transition edge phonon sensors

    Page(s): 1347 - 1350
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    The authors present data on the operation of thin-film superconducting strips of titanium as phonon sensors on the surface of silicon crystals. The superconducting films are biased at the foot of the resistive transition in temperature and below the critical latching current (the current above which a normal region in the film grows from self-heating). The interaction of an incident X-ray in the Si crystal generates a phonon source which propagates to the surface at the speed of sound. Such an event produces a several-microsecond-long self-terminating voltage pulse which is proportional to the amount of the sensor area driven normal. It is shown that these Ti superconducting transition edge sensors operated at 0.3 K have sufficient resolution for detecting particles with energy deposition above several keV, which makes them good candidates for use in neutrino (and other) experiments View full abstract»

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  • A Multiple Security Domain Model of a Drive-by-Wire System

    Page(s): 369 - 374
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1166 KB) |  | HTML iconHTML  

    Traditional security models partition the security universe into two distinct and completely separate worlds: us and them. This partition is absolute and complete. More complex situations are most commonly treated as sets of increasingly more secure domains. This view is too simplistic for cyber-physical systems. Absolute divisions are conceptually clean, but they do not reflect the real world. Security partitions often overlap, frequently provide for the high level to have complete access to the low level, and are more complex than an impervious wall. We present a model that handles situations where the security domains are complex or the threat space is ill defined. To demonstrate our method, we examine a 'drive by wire' system from both the traditional view and in light of the modern reality. This paper examines the system from the viewpoint of the driver with special emphasis on the driver's inability to determine who, or what, is actually in control of the automobile during critical situations. View full abstract»

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  • Long range resonant tunneling in quantum cascade structures

    Page(s): 162103 - 162103-3
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    Tunneling transport in a quantum cascade detector is investigated. With regard to coherent transport in quantum cascade lasers, a Kazarinov–Suris approach R. F. Kazarinov and R. A. Suris, [Sov. Phys. Semicond. 6, 120 (1972)] needs to be modified through the introduction of an additional Fermi–Dirac factor in order to properly model the experimental data at low temperature. Electronic current is completely dominated by tunneling transport; the model here presented should help to suppress it in the future design of efficient quantum cascade detectors. View full abstract»

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  • Characterization of talker radiation pattern using a microphone array

    Page(s): II/257 - II/260 vol.2
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (360 KB)  

    A microphone array has the capability of capturing the properties of a significant portion of a talker's radiation pattern. In this paper, potential implications of measuring the radiation pattern of a talker for the recognition and enhancement of speech are discussed. Current applications of microphone arrays entail their installation in small enclosures such as a conference room or an automobile, typically placing a talker in the array's near field. Fitting a nominal acoustic model to a sparse sampling of the radiation pattern yields parameter estimates which should prove useful as features for speech recognition. Parameter-estimation results using fixed-radius sources (loudspeakers) are presented. Other considerations unique to placement of a talker in close proximity to an array are discussed View full abstract»

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  • Real-time Hardware-in-the-Loop simulation for optimal Dc microgrid control development

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1097 KB) |  | HTML iconHTML  

    Microgrids are an emerging approach to achieve the goals of increased reliability, availability, efficiency and renewable energy usage. Many advanced control strategies have been developed to achieve these goals. However, final development and validation of the controls can be difficult due to the need for large and costly hardware testbeds. Real-time hardware-in-the-loop (HIL) simulators can enable the emulation of complex microgrid testbeds while developing the real-time control hardware to implement and verify theoretical optimal control strategies. This paper presents the development of loss-optimal and energy storage optimization of dc microgrids in distributed digital signal processor (DSP) hardware using HIL test setup. View full abstract»

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  • A Picture Archiving and Communication System based on an open and distributed architecture

    Page(s): 1197 - 1198
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (138 KB)  

    The Picture Archiving and Communication System (PACS) under development at the University Hospital of Geneva is part of a large hospital information system and is intended as a hospital-wide image management system for radiological and non-radiological images. This system is based on an open architecture regrouping equipment from multiple vendors in a distributed topology. The image archival is organized in multiple locations geographically distributed in the hospital. These regional archives are logically linked together to provide a virtual access to all images generated from different imaging modalities. View full abstract»

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  • Design and Implementation of Robust Time/Frequency Offset Tracking Algorithm for MIMO-OFDM Receivers

    Page(s): 1191 - 1195
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2886 KB) |  | HTML iconHTML  

    In this paper, the robust time and frequency offset tracking algorithms and architecture for high throughput wireless local area network (WLAN) systems are presented. The designed architecture has feedback and feed forward compensation loop with well defined loop filter coefficients obtained by various experiments for practical implementation. Considered functional blocks include residual CFO estimator, carrier phase estimator, and timing error estimator. In addition to the algorithm descriptions of these blocks, the implementation method is presented, as they are modeled in the floating/cycle and bit true fixed point C model. These C models have been used as a reference for RTL coding and its verification. The design has been implemented successfully on an FPGA device. The proposed tracking method produces results very close to that of the offset-free system View full abstract»

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  • Characteristics of Nb-based Josephson junctions at a temperature below 1 K

    Page(s): 1354 - 1357
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    A lithographic technique for Josephson LSI (large scale integrated) circuits was applied to the production of a superconducting tunnel junction for radiation detection. Nb-Al/aluminum oxide/Nb tunnel junctions with different junction sizes and barrier oxidation times have been fabricated. The current-voltage curves were measured in the temperature range from 4.2 to 0.45 K. The junctions showed some amounts of leakage current, which remained below 2 K. The behavior of the leakage current was successfully understood from its experimental dependence on the junction size View full abstract»

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  • EINSPECT: Evolution-Guided Analysis and Detection of Malicious Web Pages

    Page(s): 375 - 380
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (457 KB) |  | HTML iconHTML  

    Most existing work to thwart malicious web pages capture maliciousness via discriminative artifacts, learn a model, and detect by leveraging static and/or dynamic analysis. Unfortunately, there is a two-sided evolution of the artifacts of web pages. On one hand, cybercriminals constantly revamp attack payloads in malicious web pages. On the other hand, benign web pages evolve to improve content rendering and interaction with users. Consequently, the onceprecise detection techniques suffer from limitations to cope with the evolution, resulting in malicious web pages that escape detection. In this paper, we present EINSPECT, an evolution-aware and learning-based approach to address evolution of web page artifacts to more precisely analyze and detect malicious web pages. EINSPECT continuously tunes its detection models to automatically decide the best interplay of features and learning algorithms to embrace the evolution of web page artifacts into the analysis and detection. We have implemented and evaluated our approach and the results show that EINSPECT is able to improve the effectiveness of analysis and detection ofmalicious web pages while aligning the detection models with the continuous evolution of web page artifacts. View full abstract»

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  • Synthesis of difference patterns via uniform amplitude sparse arrays

    Page(s): 554 - 556
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (238 KB)  

    The synthesis of difference patterns via linear arrays, the elements of which are fed with the same amplitude, is proposed as a way to simplify the receiving chain and improve the efficiency of the antenna. The problem is solved by means of suitable analytical procedures based on a `density taper` approach. In particular, two different techniques are introduced and compared on the basis of a set of numerical examples. It is shown that one of them definitely outperforms the other one, and that constraints of practical interest can be satisfactorily fulfilled. View full abstract»

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  • An approach for the higher efficiency in the HIT cells

    Page(s): 866 - 871
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (326 KB) |  | HTML iconHTML  

    The highest conversion efficiency to date of 21.5% (confirmed by AIST) with a size of 100.3 cm2 has been achieved in an HIT cell. Because of this high efficiency and the cell's superior temperature characteristics, HIT cells are highly regarded by consumers. Sanyo will increase the production volume of cells and modules to meet the demand both inside and outside of Japan. We have been investigating suitable materials based on Sanyo's technology for fabricating high-quality a-Si solar cells to obtain higher build-in potential and control the junction properties, and have been studying how to treat the surface to create a good interface without introducing any damage. We will continue our efforts to obtain even higher levels of conversion efficiency by using the high potential that this structure has. View full abstract»

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  • Advantages and disadvantages of Shanxi FDI Absorption Capacity based on Grey Relational Entropy

    Page(s): 2376 - 2380
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (181 KB) |  | HTML iconHTML  

    By using the analyzing method of Grey Relational Entropy, this paper makes specific analysis of the elements which affected. Combined with the status of Shanxi investment environment, we can find the primary and secondary order of the specific elements. And it is easy for seeking the channels and countermeasures to enhance Shanxi FDI Absorption Capacity effectively by conducting in-depth analysis. View full abstract»

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  • A model-based technique for the fault detection of rolling element bearings using detection filter design and sliding mode technique

    Page(s): 2593 - 2598 vol.3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (584 KB)  

    A model-based technique for the fault detection of rolling element bearings in a rotor-bearing system is presented. First, a one-dimensional, multiple degree-of-freedom vibration model for rotor-bearing systems is derived. Based on the theory of detection filter design, two outputs (inner and outer ring acceleration) are defined to enable the detection of inner and outer raceway faults. Simulation is used to illustrate the results of the detection filter. Moreover, due to the noise susceptibility of vibration signals a robust monitoring system, a sliding mode detector, is presented. The sliding mode detector is capable of isolating fault surfaces in the residual space of the detection filter View full abstract»

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  • Study about injury and control of vehicle emission to person

    Page(s): 745 - 747
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (151 KB) |  | HTML iconHTML  

    With the development of vehicle industry, the vehicles bring much convenience as well as much pollution to our daily life which took injury and threaten to our health. This paper has elaborated the current domestic and international vehiclemotive emission pollution situation and characteristics. it also analyzed the injury mechanism and consequences of emission gas such as carbon monoxide and nitrogen oxides, sulfur dioxide, hydrocarbons, exhaust particulate and so on. According to our country's actual situation, it has put forward specific measures to control emissions. View full abstract»

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  • Technical Committee - INFOCOM 2007

    Page(s): vii - xii
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    Freely Available from IEEE
  • Fuzzy logic: issues, contentions and perspectives

    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (84 KB)  

    There has been a rapid growth in the number and variety of applications of fuzzy logic. The successes of fuzzy logic have also generated a skeptical reaction. Most of the criticisms directed at fuzzy logic are rooted in a misunderstanding of what it is and/or a lack of familiarity with it. In many cases, what is not recognized is that the term fuzzy logic (FL) is actually used in two different senses. In a narrow sense, fuzzy logic (FLn) is a logical system which is an extension of multivalued logic and is intended to serve as a logic of approximate reasoning. But in a wider sense, fuzzy logic (FLw) is more or less synonymous with the theory of fuzzy sets (FST). Today the term fuzzy logic is used predominantly in its wider sense. It is in this sense that any field X can be fuzzified-and hence generalized by replacing the concept of a crisp set in X by a fuzzy set. What is gained through fuzzification is greater generality, higher expressive power, an enhanced ability to model real-world phenomena and a methodology for exploiting the tolerance for imprecision. Most of the applications of fuzzy logic relate to control in the context of industrial systems and consumer products. What is discernible, however, is (a) the trend toward the use of fuzzy logic in task-oriented-rather than set-point-oriented-control; and (b) the incorporation of fuzzy logic and neural network techniques in the conception and design of complex systems in which control and expert system techniques are used in combination View full abstract»

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  • [Copyright notice]

    Page(s): 1
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    Freely Available from IEEE
  • Causal probabilistic modelling for clinical decision support in the high dependency environment

    Page(s): 869 - 870
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (172 KB)  

    A physiologically-based model of the relevant cardiovascular, respiratory and associated processes of a patient resident in a high dependency environment is described. The model will be implemented using a Causal Probabilistic Network, and will be tuned to represent the individual patient. It will provide advice, for instance regarding changes in ventilator therapy, and the model will also be used to detect and correct equipment malfunction and operator error. View full abstract»

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  • SNMP-Based Approach to Load Distribution in IEEE 802.11 Networks

    Page(s): 1196 - 1200
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2252 KB) |  | HTML iconHTML  

    In an IEEE 802.11 network, the traffic load collectively given by wireless stations (WSs) is usually not fairly shared by all available access points (APs), as WSs independently select APs to camp on. Prior approaches toward this problem either need to modify AP's behavior or require bandwidth negotiation and agreement enforcement between APs and WSs. These approaches are not practical due to their inability to apply to APs already in use. This paper proposes an application-layer approach, where a dedicated server is deployed to collect load-related information from APs utilizing SNMP (simple network management protocol). Our approach applies to off-the-shelf APs and has been proven very effective through thoughtful experiments View full abstract»

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  • Environmentally Robust MEMS Vibratory Gyroscopes for Automotive Applications

    Page(s): 1895 - 1906
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3397 KB) |  | HTML iconHTML  

    Automotive applications are known to impose quite harsh environmental conditions such as vibration, shock, temperature, and thermal cycling on inertial sensors. Micromachined gyroscopes are known to be especially challenging to develop and commercialize due to high sensitivity of their dynamic response to fabrication and environmental variations. Meeting performance specifications in the demanding automotive environment with low-cost and high-yield devices requires a very robust microelectromechanical systems (MEMS) sensing element. This paper reviews the design trend in structural implementations that provides inherent robustness against structural and environmental parameter variations at the sensing element level. The fundamental approach is based on obtaining a gain and phase stable region in the frequency response of the sense-mode dynamical system in order to achieve overall system robustness. Operating in the stable sense frequency region provides improved bias stability, temperature stability, and immunity to environmental and fabrication variations. View full abstract»

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