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One- and two-way communication with digital compressed visual signals is now an integral part of the daily life of millions. Such commonplace use has been realized by decades of advances in visual signal compression. The design of...
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One- and two-way communication with digital compressed visual signals is now an integral part of the daily life of millions. Such commonplace use has been realized by decades of advances in visual signal compression. The design of effective, efficient compression and transmission strategies for visual signals may benefit from proper incorporation of human visual system (HVS) characteristics. This paper overviews psychophysics and engineering associated with the communication of visual signals. It presents a short history of advances in perceptual visual signal compression, and describes perceptual models and how they are embedded into systems for compression and transmission, both with and without current compression standards.
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In this paper, the problem of stability on stochastic systems with state-dependent switching is investigated. To analyze properties of the switched system by means of Itô's formula and Dynkin's formula, it is critical to show swi...
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In this paper, the problem of stability on stochastic systems with state-dependent switching is investigated. To analyze properties of the switched system by means of Itô's formula and Dynkin's formula, it is critical to show switching instants being stopping times. When the given active-region set can be replaced by its interior, the local solution of the switched system is constructed by defining a series of stopping times as switching instants, and the criteria on global existence and stability of solution are presented by Lyapunov approach. For the case where the active-region set can not be replaced by its interior, the switched systems do not necessarily have solutions, thereby quasi-solution to the underlying problem is constructed and the boundedness criterion is proposed. The significance of this paper is that all the results presented depend on some easily-verified assumptions that are as elegant as those in the deterministic case, and the proofs themselves provide design procedures for switching controls.
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This paper investigates the problems of state observer design and observer-based integral sliding-mode control (SMC) for a class of Itô stochastic systems subject to simultaneous input and output disturbances. A new type of slidi...
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This paper investigates the problems of state observer design and observer-based integral sliding-mode control (SMC) for a class of Itô stochastic systems subject to simultaneous input and output disturbances. A new type of sliding-mode-based descriptor observer method is developed to approximate the system state and disturbance vectors. An integral-type SMC scheme is proposed based on the state estimation to stabilize the overall system. The main contributions of this approach are as follows: 1) The desired estimations of state and disturbance vectors can be obtained simultaneously, and 2) in the designed sliding-mode observer, the integral term of the Itô stochastic noise is eliminated in the proposed sliding-mode surface by a matrix design; thus, the reachability of the sliding-mode surface is strictly guaranteed. Finally, the proposed approach is applied to the disturbance reconstruction problem of an F-18 aircraft model to illustrate the effectiveness and applicability.
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Sleep apnea is a common condition that poses serious health risks. Current state-of-the-art technology for diagnosing and assessing sleep apnea is obtrusive, expensive, and lacks integration/analysis of important cardiovascular an...
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Sleep apnea is a common condition that poses serious health risks. Current state-of-the-art technology for diagnosing and assessing sleep apnea is obtrusive, expensive, and lacks integration/analysis of important cardiovascular and respiratory parameters. This paper evaluates a novel unobtrusive multiparameter sleep apnea monitor, namely, the Biopeak chest belt monitor, and describes a collection of associated algorithms for the detection of sleep apnea and assessment of the extent of the resulting physiological disturbance. The system uses dry electrodes to acquire electrocardiogram, respiratory, and stroke volume data and analyzes multiple physiological parameters from it. In a pilot investigation on eight healthy subjects simulating a total of 66 obstructive sleep apnea (OSA) events with Mueller maneuvers, the proposed system achieves an accuracy of 95.6%, a specificity of 97.2%, and a sensitivity of 93.8% for identifying these events. Moreover, the response of the simulated OSA events on the multiple physiological parameters conforms to earlier published work. We thus conclude that the proposed chest belt system has potential to be used for reliable sleep apnea detection and comprehensive evaluation of cardiovascular and respiratory parameters in sleep apnea.
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Oscillometry is a popular technique for automatic estimation of blood pressure (BP). However, most of the oscillometric algorithms rely on empirical coefficients for systolic and diastolic pressure evaluation that may differ in va...
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Oscillometry is a popular technique for automatic estimation of blood pressure (BP). However, most of the oscillometric algorithms rely on empirical coefficients for systolic and diastolic pressure evaluation that may differ in various patient populations, rendering the technique unreliable. A promising complementary technique for automatic estimation of BP, based on the dependence of pulse transit time (PTT) on cuff pressure (CP) (PTT–CP mapping), has been proposed in the literature. However, a theoretical grounding for this technique and a nonparametric BP estimation approach are still missing. In this paper, we propose a novel coefficient-free BP estimation method based on PTT–CP dependence. PTT is mathematically modeled as a function of arterial lumen area under the cuff. It is then analytically shown that PTT–CP mappings computed from various points on the arterial pulses can be used to directly estimate systolic, diastolic, and mean arterial pressure without empirical coefficients. Analytical results are cross-validated with a pilot investigation on ten healthy subjects where 150 simultaneous electrocardiogram and oscillometric BP recordings are analyzed. The results are encouraging whereby the mean absolute errors of the proposed method in estimating systolic and diastolic pressures are 5.31 and 4.51 mmHg, respectively, relative to the Food and Drug Administration approved Omron monitor. Our work thus shows promise toward providing robust and objective BP estimation in a variety of patients and monitoring situations.
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The main goal of this paper is to provide an analytical study on the statistical behaviors of the electricity price at various conditions of the load and the network. In order to achieve this goal, a novel two-step modeling is pro...
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The main goal of this paper is to provide an analytical study on the statistical behaviors of the electricity price at various conditions of the load and the network. In order to achieve this goal, a novel two-step modeling is proposed for the electricity price. At the first step, it is proved that there is a linear relationship between the locational marginal prices (LMP) and the strategies of generating companies (GenCos). In this linear relationship, the LMP is decomposed to the weighted summation of the strategies of marginal units plus constant value. At the second step, the LMP is modeled by classic central limit theorem (CLT). Using this model an analytical relationship is derived between the price discovery mechanism and characteristics of its probability density function (pdf). As a result, this paper shows analytically that increasing system load causes the price pdf deviates from the normal distribution. On the other hand, by decreasing system load, the electricity price distribution tends toward the normal distribution. The statistical studies on the real power markets data confirm these analytical results. Furthermore, the simulation results of the IEEE 300-bus test system illustrate the efficiency of the proposed model.
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Among the benefits obtained by the cabling of telephone circuits is the substantial reduction in magnetically induced voltages that can be realized from the shielding action of the lead sheath. Even greater shielding is attainable...
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Among the benefits obtained by the cabling of telephone circuits is the substantial reduction in magnetically induced voltages that can be realized from the shielding action of the lead sheath. Even greater shielding is attainable if the cable is provided with a steel armor or is installed in iron pipe conduit. In this paper is presented a method for the quantitative prediction of the electromagnetic shielding effected by such iron-surrounded telephone cable sheaths, experimental verification of its applicability, and the necessary impedance data for its utilization.
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A single feed printed monopole antenna with switchable polarisation with reduced antenna size is proposed. The radiating element is in the form of two monopole rectangular patches fed by a single microstrip line. To reduce the siz...
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A single feed printed monopole antenna with switchable polarisation with reduced antenna size is proposed. The radiating element is in the form of two monopole rectangular patches fed by a single microstrip line. To reduce the size of the patches and to provide dual polarised operation, each patch is perturbed by two L-shaped slots. Such a structure can produce two orthogonal linear polarisations by switching only one pin diode, which is the most interesting feature of the design. To further reduce the size of the antenna a meandered stub attached to the transmission line is employed. The antenna is fabricated on the low-cost FR4 substrate with an overall size of 26 ?? 19 mm2.
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Stator faults contribute to 38% of all electrical machine failures. The detection of inter-turn stator fault has therefore been the focus of research for many years. The aim of this research is to provide new condition monitoring ...
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Stator faults contribute to 38% of all electrical machine failures. The detection of inter-turn stator fault has therefore been the focus of research for many years. The aim of this research is to provide new condition monitoring technique for doubly fed induction generator during inter-turn fault. The contribution of this research is to formulate a method of doubly-fed induction generator (DFIG) inter-turn stator fault detection that is applicable when this machine operates during steady-state condition. New proposed hybrid model (ABC/dq) has been presented for modelling of DFIG with inter-turn stator fault. Finally a new index has been defined for the detection of inter-turn stator fault in DFIG that employs wavelet analysis of the stator currents and energy of a signal which has been called fault detection index. Proposed index is robust to variation of operating point, percentage of turn fault, stator and rotor resistance and sampling frequency.
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