An improved efficiency of fuzzy logic control of PMBLDC for PV pumping system

This paper presents an analysis by which the dynamic performances of a permanent magnet brushless DC (PMBLDC) motor is controlled through a hysteresis current loop and an outer speed loop with different controllers. The dynamics of the photovoltaic pumping drive system with (PI) and a fuzzy logic (FL) speed controllers are presented. In order to optimize the overall system efficiency, a maximum power point tracker is also used. Simulation is carried out by formatting the mathematical model for photovoltaic source, MPPT, motor and pump load. The results for such complicated and nonlinear system, with FL speed controller show improvement in transient response of PMBLDC drive over conventional PI. The effectiveness of the FL controller is also demonstrated.     

“统计信息”与“信息高速公路”

本文从我国统计信息事业的现状，提出了关于第一类统计与第二类统计。同时指出统计信息事业的迅速发展与繁荣，首先必须实现两类统计的相互渗透；其二必须与计算机技术密切结合，以建立起各级各类统计信息的高速公路，使统计信息更好地为我国的科技、经济、社会的全面发展提供有效的服务。     

Volumetric behaviour of binary and ternary liquid systems composed of ethanol, isooctane, and toluene at temperatures from (298.15 to 328.15) K. Experimental data and correlation

The densities and speeds of sound of (ethanol + isooctane), (ethanol + toluene), and (ethanol + isooctane + toluene) were measured at four temperatures over the range (298.15 to 328.15) K, and the respective values of excess volumes and adiabatic compressibility κ_S were calculated. The and κ_S values for the binary systems were fitted to the Redlich–Kister equation. The respective ternary data together with corresponding binary data were then fitted to the modified Redlich–Kister equation considering various numbers of ternary constants. It was found that even for the systems containing self-associating alcohol, only one ternary parameter is sufficient to describe well the ternary system.     

Wasserstein convergence rates for random bit approximations of continuous Markov processes

We determine the convergence speed of a numerical scheme for approximating one-dimensional continuous strong Markov processes. The scheme is based on the construction of certain Markov chains whose laws can be embedded into the process with a sequence of stopping times. Under a mild condition on the process' speed measure we prove that the approximating Markov chains converge at fixed times at the rate of 1/4 with respect to every p-th Wasserstein distance. For the convergence of paths, we prove any rate strictly smaller than 1/4. Our results apply, in particular, to processes with irregular behavior such as solutions of SDEs with irregular coefficients and processes with sticky points.     

Computerized instrumentation system for monitoring the tractor performance in the field

A high precision computerized instrumentation package was developed and mounted on a 50 kW tractor to monitor and measure various performance parameters of a tractor and implement system. The system was intended to be used for the compilation of a database of draft requirements of tillage implements. The system designed to measure: three-point linkage forces, ground speed, tillage depth, fuel consumption, forward speed, slip, engine speed, hydraulic pressure and fluid temperatures. The data acquisition unit was based on a high speed multi processors Campbell Scientific CR3000 data logger linked to a microcomputer using suitable transducer. The average calibration constants for the rear wheel speed, fuel consumption and three point linkage transducers were 0.0364 m/pulse, 0.000142857 l/pulse and 0.66 mV/kN respectively. The data acquisition system was capable of scanning rate up to 100 K sample/s. Data acquisition system was developed to measure draft of primary tillage implements in vertisol.     

Predicting thermophysical properties of biodiesel fuel blends using the SAFT-VR approach

Modeling of thermophysical properties and phase equilibria of long-chain methylesters mixtures are presented, using the SAFT-VR approach for mixtures. Molecules are represented as chains of spherical segments that can associate due to the presence of short-ranged attractive sites, using previous molecular parameters obtained for pure fatty acid methyl esters. These attractive sites as well as the intermolecular interactions between monomers segments are modeled via variable-ranged square-well potentials. The cross-energy binary-interaction parameter of the extended Berthelot combining rule was fitted to liquid densities and speed of sound. Very good predictions are obtained for isochoric heat capacities and for binary and ternary phase diagrams.     

Photoglottographic measures in parkinson's disease

This study examines the usefulness of photoglottographic measures in reflecting the phonatory effect of Parkinson's disease. In the first experiment, data obtained by photoglottography were compared between 15 male patients with Parkinson's disease and 15 normal male speakers of similar age. Six photoglottographic parameters, mean open quotient (OQ), mean speed quotient (SQ), perturbation of open quotient (POQ), perturbation of speed quotient (PSQ), frequency perturbation ratio (FPR), and amplitude perturbation ratio (APR), in sustained vowel phonation were investigated. Increased SQ (t = -2.731, df = 28, P = 0.011) and POQ (t = -2.584, df = 28, P = 0.015) were significantly associated with data from patients in comparison to normal speakers. The FPR, APR, and OQ were not significantly different between normal subjects and patients. A follow-up experiment, including 12 female and 19 male patients with Parkinson's disease, was designed to evaluate the sensitivity of SQ and POQ in detecting vocal dysfunction. The sensitivity of SQ was found to be relatively high (93.5%), while that of POQ was low (45.2%). Methodological issues regarding the effects of gender, age, stage of the disease, and treatment on photoglottographic measures in Parkinson's disease were discussed.     

Reducing temperature influence on dry quantitative ultrasound bone assessment with constant temperature control

Nowadays, ultrasonic bone assessment is increasingly being used to assess bone status. Therefore, the purpose of this study was to enhance the precision of ultrasonic bone assessment by reducing the influence of temperature in a dry, gel coupled transducer system. A warm airflow generator was designed to make the measurement temperature constant (35 ± 1 °C). Thirty people were recruited for the evaluation of in-vivo performance. The short-term precision was performed 10 times with repositioning during a consecutive measurement session within 20 min. It was expressed as root-mean square average of coefficient of variation, which is abbreviated for CV_RMS. The CV_RMS was 3.84% for broadband ultrasound attenuation, and 0.30% for speed of sound. The Pearson correlations between gel coupled transducer system and dual energy X-ray absorptiometry (DEXA) were 0.808 (p < 0.001) for broadband ultrasound attenuation, and 0.586 (p < 0.005) for speed of sound. The result showed the high performance of reproducibility and the significant (p < 0.005) correlations with DEXA in the dry, gel coupled transducer system.     

多卜勒计程仪

本文简要回顾多卜勒计程仪的发展和用途，分析了多卜勒计仪为导航设备的优点，工作原理，主要性能及组成部件，最后介绍了多卜勒计程仪在我国的设计情况。     

Feedback control strategies for the Liu chaotic system

This Letter proposed three strategies of the dislocated feedback control, enhancing feedback control and speed feedback control of the Liu chaotic system to its unstable equilibrium points. It is found that the coefficients of enhancing feedback control and speed feedback control are smaller than those of ordinary feedback control, so, the complexity and cost of the system control are reduced. Theoretical analysis and numerical simulation are given, revealing the effectiveness of these strategies.