Selection of Protector Parameters for Right Bidirectional Transducers

The paper compares experimental and calculated pulse shapes and spectra of signals for bidirectional right transducers with radically different protectors, namely, those from epoxy glue with a filler and ceramic. The new data support the previously made conclusion (from calculated parameters of emitted pulses) that in protectors from composite materials (with low propagation velocities of longitudinal elastic waves) signal spectra can have several pronounced peaks, and their waveforms can exhibit beats (oscillating amplitude modulation).     

Performance evaluation of a multichannel transceiver system forADSL and VHDSL services

The authors study the performance of a multichannel modulation method for asymmetric digital subscriber lines (ADSLs) and very high-speed digital subscriber lines (VHDSLs). In the ADSL case, over all unloaded North American subscriber lines in the test set, a unidirectional 1.536 Mb/s data rate service from the end office to the customer premises is possible on a single twisted pair at an error rate of 10^-7 with at least a 6 dB margin used coded multichannel modulation with sufficient transmit power. In the VHDSL case, data rates in excess of 100 Mb/s can be transmitted reliably, at an error rate of 10^-7, using uncoded multichannel modulation on a single twisted pair over a distance ⩽150 ft with a sufficiently high sampling rate (≈24 MHz) and transmit power. It is shown that a cost-effective multichannel transceiver design suggested for high-speed digital subscriber line (HDSL) service will also work well for ADSL and VHDSL services with only minimal modifications     

Management of the patient with minor traumatic brain injury

Staff in the accident and emergency department and critical care unit are often confronted with patients who have sustained life-threatening injuries. In such situations the symptoms of a minor traumatic brain injury (MTBI) may be missed. It is important that, when the physical symptoms begin to subside, nurses are aware of the symptoms of MTBI and respond accordingly. A post-concussion syndrome may develop 2 weeks to 2 months after a MTBI. This syndrome can affect the patient's ability to perform the usual activities of living. This article defines MTBI, describes the symptoms encountered in patients with MTBI, and outlines the pathophysiology, clinical findings, treatment and nursing interventions.     

Virtual Models of the Synthesis of Nanosystems

The problem of synthesis of nanosystems reproducible on the microscopic level is analyzed in the framework of the adiabatic approximation. Different methods for describing the structure of polyatomic systems are discussed. Special attention is focused on algorithmic information. The operation of a configurational machine that makes it possible to simulate actually proceeding chemical processes, in particular, synthesis of nanosystems, is considered in detail.     

Dynamical adaptive synchronization

The notions of dynamical synchronization and adaptive dynamical synchronization problems are introduced. The algorithm solving adaptive synchronization problem for a subclass of Lurie systems with exciting input is proposed. The performance and potentialities of proposed solutions are demonstrated by two examples related to formation control and self‐organization of swarm systems. Copyright © 2006 John Wiley & Sons, Ltd.     

Assessment of underground cable ratings based on distributed temperature sensing

Numerous power utilities have installed advanced distributed temperature sensing (DTS) systems to measure the temperature of underground cables. This paper presents a general procedure for real-time assessment of underground cable ratings based on DTS. After the identification and location of hot spots on a cable, the cable installation data, load, and DTS-recorded temperature over a period of time are used to estimate soil thermal parameters and assess cable ratings under normal and overloading conditions. In order to accurately estimate soil thermal parameters, a combined technique of the finite-element method and gradient-based optimization is used. The technique was validated in the laboratory and applied to a rating assessment of a 230-kV/500-MVA cable circuit. The assessed continuous and emergency ratings are helpful in improving the operation of this circuit.     

Probabilistic Wind Farms Generation Model for Reliability Studies Applied to Brazilian Sites

This paper presents a computer model for the probabilistic representation of wind farms generation for reliability studies, which can provide an annual estimation of energy production and calculate several performance indexes. The model combines the stochastic characteristics of wind speed with the operational information of the turbines, such as the failure and repair rates, representing the wind farm by a Markov process. The simulations are made with real time series of wind speed of several Brazilian regions and actual turbine models. The influence of some wind farm and installation site characteristics on the results are evaluated, such as the wind speed statistical clustering technique, the number and type of the turbines, and the failure and repair rates. The results obtained reproduce successfully the behavior of the components considered in the model     

Electric arcing burn hazards

The paper presents recent results in the area of high-power testing aimed at improving the safety of electrical staff working on live equipment. The driver for this work is the American Guide (IEEE 1584) on such exposure hazards, which has the potential for international adoption and, in the authors' opinion, does not provide a suitable methodology for assessing the hazard. A selection of results is presented, obtained in a high-power-system-supplied commercial test laboratory, using the latest charge-coupled device (CCD)-based high-speed video-recording methods. Results are reported for 415-V currents in the range of 1000-70 000 prospective root mean square (rms) amperes and for tests at 5000 V in the range of 1000-27 000 A. The impact of conventional protective devices is included together with some disturbing video results for circuit-breaker-protected systems. The major part of the material in this paper was first presented at the 7th International Conference on Electric Fuses and Their Applications, Jurata, Poland, in 2003.