Lorentz Force Sigmometry

The present communication reports a new technique for the contactless measurement of the specific electrical conductivity of a solid conductor or an electrically conducting fluid.We tenn the techniqueLorentz Force Sigmometrywhere the neologismSigmometryis derived fiom the Greek letter sigma,often used to denote the electrical conductivity.Lorentz force sigmometry(abbreviated LoFoS)is based on similar principles as the traditional eddy current testing but allows a larger penetration depth and is less sensitive to variations in the distance between the sensor and the sample.Here we formulate the theory of LoFoS and numerically compute the calibration function which is necessary for determining the unknown electrical conductivity from the measurement of a Lorentz force.     

Efficient computation of the Zassenhaus formula

A new recursive procedure to compute the Zassenhaus formula up to high order is presented, providing each exponent in the factorization directly as a linear combination of independent commutators and thus containing the minimum number of terms. The recursion can be easily implemented in a symbolic algebra package and requires much less computational effort, both in time and memory resources, than previous algorithms. In addition, by bounding appropriately each term in the recursion, it is possible to get a larger convergence domain of the Zassenhaus formula when it is formulated in a Banach algebra.     

Identification of acid attack on concrete of a sewage system

A sewage system, 300 km long, showed superficial deterioration of concrete just 2 years after construction. In order to re-habilitate the structure, it was necessary to identify the main mechanism of deterioration and to understand the heterogeneous distribution of the damage observed. The study was performed in a three stepped program: site investigation and sampling, laboratory tests and concrete petrography. During the site inspection it was recognized that there was dissolution of the concrete in some sectors of the structure, with the aggregate particles protruding in relation to the undulated surface. In some places a white to yellowish putty-like product could be excavated by hand. The main deterioration was observed above the water level. The composition of the atmosphere inside the sewer was assessed and a high content of hydrogen sulfide was detected. Sampling was performed in different structural elements which showed diverse exposition to the aggressive environment. Impregnated thin sections of concrete with fluorescent yellow dye were analyzed by optical microscope. Concrete petrography showed to be crucial for the diagnoses. The study showed that the putty-like product was composed by gypsum with small residual particles of siliceous sand which resisted to the acid attack. SEM/EDS was used to evaluate the content of sulfur in different sections of the concrete cores and also to characterize the putty-like product at the surface of the concrete. This study led to the confirmation of the presence of an extensive sulfuric acid attack with rather minor sulfate attack within the concrete due to the exposition to aggressive environment. It also showed that behind the superficial deteriorated level, the concrete was sound with no signs of internal deleterious reactions. Ammonium content in residual water might have also contributed to the superficial deterioration of the concrete sewer.     

Assessing circuit breaker performance using condition-based data and Bayesian approach

This paper proposes a methodology to assess the performance of circuit breaker utilizing its control circuit data. Various performance indices are defined to assess the condition of breaker using probability distributions. Bayesian updating approach is implemented to update these indices as the new data becomes available. An approximation in implementing the Bayesian approach to deal with large amounts of data on-line is considered. The methodology is applied to data recorded at different times during both open and close operations on a group of similar circuit breakers. The methodology can be used to quantify the effect of maintenance making use of the defined performance indices, which further helps in developing system level risk-based decision approaches for maintenance optimization.     

An Algorithm-Hardware-System Approach to VLIW Multimedia Processors

Very Long Instruction Word (VLIW) processor architectures for multimedia applications are discussed from an algorithm, hardware and system based point of view. VLIW processors show high flexibility and processing power, as well as a good utilization of resources by compiler-generated code, but their exclusive exploitation of instruction level parallelism (ILP) decreases in efficiency as the degree of parallelism increases. This is mainly caused by characteristics of multimedia algorithms, increasing wiring delays, compiler restrictions, and a widening gap between on-chip processing speed and available bandwidth to external memory. As new multimedia applications and standards continue to evolve (MPEG-4), the demand for higher processing power will continue. Therefore, parallel processing in all its available forms will have to be exploited to achieve significant performance improvements. We show that, due to the diminishing returns from a further increase in ILP, multimedia applications will benefit more from an additional exploitation of parallelism at thread-level. We examine how simultaneous multithreading (SMT), a novel architectural approach combining VLIW techniques with parallel processing of threads, can efficiently be used to further increase performance of typical multimedia workloads.     

Use of smoothing splines for analysis of backscattered ultrasonic waveforms: application to monitoring of steroid treatment of dystrophic mice

Duchenne muscular dystrophy (DMD) is an X-linked genetic disease characterized by progressive weakness and wasting of skeletal and cardiac muscle; boys present with weakness by the age of 5 years and, if left untreated, are unable to walk without assistance by the age of 10 years. Therapy for DMD has been primarily palliative, with oral steroids emerging as a first-line approach even though this treatment has serious side-effects. Consequently, low-cost imaging technology suitable for improved diagnosis and treatment monitoring of DMD would be of great value, especially in remote and underserved areas. Previously, we reported use of the logarithm of the signal energy, log [E(f)], and a new method for ultrasound signal characterization using entropy, H(f), to monitor prednisolone treatment of skeletal muscle in a dystrophin-deficient mouse model. Three groups were studied: mdx mice treated with prednisolone, a control group of mdx mice treated with saline, and a control group of wild-type mice treated with saline. It was found that both log [E(f)] and H(f) were required to statistically differentiate the three groups. In the current study, we show that preprocessing of the raw ultrasound using optimal smoothing splines before computation of either log [E(f)] or a rapidly computable variant of Hf, denoted I(f,∞), permits delineation of all three groups by either metric alone. This opens the way to the ultimate goal of this study, which is identification and implementation of new diagnostically sensitive algorithms on the new generation of low-cost hand-held clinical ultrasonic imaging systems.     

Design of the adaptive piecewise uniform scalar quantizer with lossless coder and Golomb-Rice code on the output, for signals with Gaussian distribution

In this paper a new compression model for signals with Gaussian distribution is presented. It consists of a piecewise uniform scalar quantizer, a lossless coder and Golomb-Rice code. Forward adaptation of this proposed model is done and constant signal-to-quantization noise ratio (SQNR) in wide range of input variances is obtained. Joined design of lossy and lossless coder is done, achieving optimal performances. Our model has small complexity since all components of the model (piecewise uniform quantizer, lossless coder and Golomb-Rice code) are very simple for realization. As an example, this model is applied on the speech signal, and it is shown that the G.712 standard is satisfied with bit-rate decrease of 1.09 bits/sample, compared to the classic uniform quantizer.     

Reverse osmosis characteristics of composite membranes prepared by plasma polymerization of allylamine. Effects of deposition conditions

A study has been conducted to determine the effects of flow configuration and reaction conditions on the performance of composite reverse osmosis membranes prepared by plasma polymerization of allylamine over a porous polymer substrate. It was established that superior membranes were obtained by using a gas-flow configuration avoiding direct monomer flow over the substrate. High rejections of NaCl could be attained when the plasma-deposited film was sufficiently thick to bridge all of the pores in the substrate. It was observed that in addition to influencing the rate of polymerization, the conditions used to sustain the plasma also affected the reverse osmosis characteristics of the deposited film. The effects of these conditions and other preparation procedures are discussed. Attempts to use infrared spectroscopy and ESCA to identify the relationship between polymer structure and reverse osmosis performance were not successful. ESCA did prove useful, though, in confirming an earlier postulated hypothesis that degradation of reverse osmosis performance is associated with the hydrolysis of nitrogen-containing structures in the plasma-deposited film.