Abstract:A hardware platform consisting of a point of load (POL) converter with a digital controller is built. The digital controller is analyzed and designed using digital redesign and direct digital approaches. The digital controller parameters are designed employing analytic methods for continuous and discrete systems, including the Bode graph method, discretetime frequency method and rootlocus method. The crossover frequency and phase margin are compared. Then the digital redesign and direct digital approaches are verified by experimentation. The steady state performances and dynamic responses are analyzed comparatively. Theoretical analysis and experimental results suggest that using the direct digital approach lowers the output voltage adjustment rate and improves the dynamic response speed.

Abstract:Reasons for the occurrence of low frequency oscillations in power system are analyzed, and the damping characteristics of asynchronized turbogenerators (ASTG) are investigated thoroughly. Based on these damping characteristics, a theory of restraining low frequency oscillation by partially replacing the traditional synchronous generator in power systems with an ASTG is proposed. A typical two machines, two area power system model is established. A simulation studying ASTG restraint of low frequency oscillation in power systems is carried out. The simulation results show that power systems incorporating an ASTG possess excellent dynamic and transient operation characteristics, and that low frequency oscillation in power systems is effectively restrained.

Abstract:We present an aeroelastic model design and method creation based on the case of an ±800 kV ultrahigh voltage (UHV) power transmission line from Xiang Jiaba to Shanghai, P. R. Chin, Both the centralized and discreted stiffness modeling methods are unsuitable for tower aeroelastic modeling. Taking these stiffness and aerodynamic characteristics into account, we introduce a new method to create an aeroelastic model that includes a semirigid model segment and Ushaped springs. Because the span of this transmission line is too long to fit within the wind tunnel in the same proportions as the tower, the proportions of the line model is condensed further. Aeroelastic test requirements can be satisfied by comparing theoretical analysis and actual measurements of the system model dynamics.

Abstract:We measure power electricfield intensity at a substation in southwestern P. R. China at various humidity levels and temperatures. Measurement data and a back propagation neural network are used to construct a model of electrical field intensity responses to fluctuations in humidity and ambient temperatures. The maximum error is 0.047 5. The results show that the power electricfield intensity increases as humidity rises when the temperature is constant; when humidity is a constant, temperature changes do not affect the regularity of the electricfield intensity in a consistent manner regularly.

Abstract:When contactless power transmission (CPT) systems are operating normally, load variation will cause the system operating frequency to drift and the resonance frequency scope to deviate from the desired level. These fluctuations in turn cause the system to vary substantially and affect its normal operation. Considering the slip road track of the primary circuit and the phase angle change between the front of the subnetwork rectifier circuit current and the voltage, we employ different circuit models to analyze the nature and size of the load for the two types of antiperceptual situations. An algorithm is derived to calculate the junior circuit parameters with the load on the rails. Simulation analysis for the load identification under two different load conditions is conducted, and the expected results achieved.

Abstract:Total least squares (TLS) is proposed to complete harmonic state estimation when parameter and measurement errors are both taken into consideration. The buses are partitioned into subsets of nonsource buses and suspicious buses, thereby reducing the number of unknown state variables. The validity and practicability of this approach is validated using the IEEE14bus harmonic testing system. The estimation precision is analyzed by random sampling 10 000 times in Matlab when measurement errors and parameter errors followed a Gaussian distribution. The results show that an accurate estimate can be obtained using TLS if parameter and measurement errors are considered.

Abstract:The effective assessment of circuit breaker status is crucially important for developing condition maintenance. Due to faults in the existing assessment method, we develop a method based on matterelement theory to assess the condition of highvoltage circuit breakers. A method based on electrical testing, mechanical properties, appearance, working environment and maintenance condition can analyze the ascription degree of each index with relevant functions and evaluate the circuit breaker status qualitatively and quantitatively. At the same time, using the analytic hierarchy process(AHP) method to determine the constant weight of every index, we introduce a variable weight model based on a balanced function. This model considers the proportionality synthetically among every index and derives variable weights by modifying the constant weights, thereby improving assessment accuracy. The condition assessment method for highvoltage circuit breakers based on matterelement theory is shown to be effective based on experimentation with an actual circuit breaker.

Abstract:The properties of silica fume concrete in natural sea water are studied, with special focus on the relationship between the freezethaw durability and chloride ion diffusion coefficients. The influence of various factors on concrete resistance to frost and chloride diffusion is studied, including the watercement ratio, equivalent silica fume dosage substitution for cement, and the amount of airentraining agent and compared with that of ordinary concrete. The results show that adding silica fume cannot improve the frost resistance of concrete but it increases resistance to chloride diffusion. Both the frost resistance and chloride diffusion properties can be improved simultaneously when silica fume is used with an airentraining agent. A silica fume content of approximately 10% is the optimum value for the composite resistance to frost and chloride diffusion. A new assessment method (Rvalue method) is proposed to evaluate the composite properties of frost resistance and chloride diffusion of marine concrete.

Abstract:The influence of calcined alum on the hydration process, the structure and intensity of hardened anhydrite, the degree of solution supersaturation, and other properties are investigated by determining setting time, hydration rate and hydration temperature increases in combination with analyzing the microstructure and intensity of hardened paste. The alum action mechanism also is revealed. The results indicate that calcined alum is a highly active excitant for anhydrite. Calcined alum can reduce setting time, increase the hydration process and intensity of anhydrite, and refine crystals. Calcined alum improves the hydration and solution performance of anhydrite and sulfate radical concentration. This subsequently raises the degree of dihydrate gypsum supersaturation. Anhydrite hydration and solution, and the spontaneous homogeneous nucleation and growth of dihydrate gypsum crystals are all accelerated.

Abstract:The type and percentage of sand affect the gradation of coarsefine aggregate and the amount of spare mortar in concrete, which further affects the resistance of fresh concrete to initial plastic shrinkage. Taking into account the engineering characteristics of sand in the area of Chongqing, P. R. China, three fine aggregates composed of superfine, medium, mixed and manufactured sand, are used to prepare high performance concrete (HPC). The effects of these three fine aggregates on initial plastic shrinkage crack are investigated. The results show that the HPC prepared with superfine sand possesses a higher initial shrinkage value than HPC prepared with mixed or medium sand. An optimal sand percentage is necessary to reduce the initial shrinkage cracking of HPC prepared with mixed or medium sand.

Abstract:Fluid flow and temperature distribution in a wide slab continuous caster mold are simulated using the commercial software FLUENT. The research results show that the longitudinal cracks in the wide slab surface with an original submerged entry nozzle (SEN) mainly are caused by weak upper flow circulation in the mold, slow heat exchange near the meniscus, and nonuniform melting of the mold powder. Therefore, a modified SEN with smaller outlet thickness, a 15° downward port angle, and convex bottom is designed to overcome the disadvantages of the original nozzle. The characteristics of the molten steel flow are analyzed by numerical simulation. The results indicate that the parameters of the optimum SEN are more highly optimized than the original SEN. The trial results also show that the optimum SEN possesses a better application effect.

Abstract:Use of the Xray diffraction method to measure microball coat thickness is studied. A mathematical model of Xray diffraction of microballs is created and solved using computer aided simulation. The relationship between diffracted X ray intensity and coat thickness is calculated with the help of a standard sample possessing a known thickness. The coat thickness of other samples can be calculated by the intensity of diffracted Xray based on the same condition. The experimental result shows that this method is a rapid, convenient, nondestructive means of measuring microball coat thickness.

Abstract:The effects of three foaming accelerators, ZnO, nanometer ZnO, and ZnO/Zn(st)2, on the thermal decomposition property of foaming agents and the ability to create microcellular foam in polypropylene (PP) microcellular foaming plastics are studied. The influence of these accelerators on the microcellular structure of PP microcellular foaming plastics is analyzed by using a thermogravimetry technique. The dispersion of foaming accelerators in resins is observed using scanning electron microscopy. It is shown that the compositing foaming accelerators exhibite a comparatively better dispersion. The properties of different accelerators containing foaming materials are investigated and compared. Compared to those without foaming accelerators, the impact strength of PP microcellular foaming plastics with foaming accelerators is significantly enhanced.

Abstract:A new hybrid respirometer is used to measure the oxygen uptake rate (OUR) of COD aerobic biodegradation process. Parameter identification and estimation of carbon oxidation process of an Activated Sludge Model are studied by combining the OUR data and mathematical fitting of curves. Coefficients of variation (CVs) for the three combined parameters estimated are below 13% for activated sludge from a laboratory and below 8% for activated sludge from a wastewater treatment plant. For single parameter estimation, the CVs are below 25% and below 10%, respectively. High measurement frequency and precision of the hybrid respirometer can improve the precision of parameter estimation. Initial concentrations of the substrate and the activated sludge of the respirometric experiment are key conditions that must be optimized to obtain highprecision parameter estimation due to their effect on OUR curve characteristics.

Abstract:We use an inexpensive adsorbent produced from orange residue found to remove the Cr(Ⅵ) from an aqueous solution. We investigate the factors influencing adsorption performance and the adsorption mechanism of the orange residue adsorbance of Cr(Ⅵ). The results show that the contact time, pH, and initial Cr(Ⅵ) solution concentration affect the adsorption process. At pH 4 and 40℃, the equilibrium is attained in about 11 hours, and adsorption quantity of the adsorbent is 12.85 mg/g with liquid/solid (hexavalent chromium vs. adsorbent) of 18 mg/g. The ideal saturated amount is 13.74 mg/g as determined by the linear least squares method. The adsorption process fits the Bangham adsorption kinetics model. At a low concentration range, the process also follows the Langmuir and Freundlich adsorption isotherms. Experimental results and the adsorption mechanism show that the orange residue adsorbent is an effective treatment for wastewater containing Cr(Ⅵ).

Abstract:The characteristics of conventional triaxial creep are obtained via a conventional triaxial creep test of gascontaining coal under different stress levels. Mathematical fitting research regarding an experimental curve is done. A constitutive model of conventional triaxial creep of gascontaining coal is developed by improving a generalized KB model. The results show that the characteristics of conventional triaxial creep of gascontaining coal are related to the load step, and creep deformation is limited by the gas and confining pressures. Curves of the order 3ε(t) describe the three steps of conventional triaxial creep tests of gascontaining coal very well; the improved generalized KB model can represent a constitutive model of the conventional triaxial creep of gascontaining coal.

Abstract:To create a model for recycling technology, a waste FR4 printed circuit board (PCB) recycling process employing supercritical fluid CO2 (SCFCO2) is studied using central composite design. The influence of temperature and treatment time on the PCB delamination ratio, latitudinal tensile strength of glass fiber sheets, and their synthesized effect are analyzed. The optimal temperature and treatment time for FR4 PCB recycling with SCFCO2 are found by building a quadratic polynomial equation model of output parameters in recycling technology. The accuracy of the derived optimal temperature and treatment time is validated by a series of experiments.

Abstract:We develop a nonlinear red tide dynamic model to study the effect on a system of two harmful phytoplankton and zooplankton and of a toxicant emitted into the environment from external sources and a toxin excreted by phytoplankton. We use modern nonlinear dynamics to discuss stability and bifurcation, and obtain the thresholds of persistence and extinction for each species. Numerical simulations are used to validate the theoretical results. The results show that a sequence of Hopf bifurcations occur at the interior equilibrium as the delay increases or the growth rates increase.

Abstract:Coal mining waste dumps are representative artificial accumulations of bulky rock and soil material. Certain factors make these dumps possess characteristics such as selforganized criticality, nonlinear shear strength of the waste accumulation. We discusse the main waste dump characteristics and subsequently produced numerical simulations of the stability of waste dumps of various heights using the Fast Lagrangian Analysis of Continua and based on the HoekBrown nonlinear strength criterion. The simulation calculation results show that the stability is a dynamic evolving process corresponding to increasing waste dump height. Safety factors, based on a nonlinear rule, vary with the waste dump height. Theoretical analysis and calculated outcomes reveal a progressive failure rule of waste dumps, and all indicate the methods we put forward are reasonable.

Abstract:To analyze the influence of the platform screen doors (PSD) on energy consumption of subway environmental control systems in northern cities and to make good use of piston wind, EnergyPlus, an energy analysis and thermal load simulation program, is used to evaluate such systems in northern cities. A computational fluid dynamics (CFD) simulation is made to model the velocity and temperature field of a subway station and to predict the effect on PSD reconstruction using Airpak. Compared to a system with automatic platform gates, a PSD system has 2% lower energy consumption. Thus, PSDs are inefficient for saving energy in northern cities. Because electricity consumption by ventilation equipment increases notably when PSDs are used, particularly by under platform exhaust fans, little difference exists in the overall energy consumption with or without PSD. More thoroughly using piston wind in transition seasons and the winter is the key to solving the high energy consumption problem. The energy analysis and CFD simulation results show that the adjustable vents in PSD can use the piston process to introduce outside air, thereby reducing ventilation energy consumption notably. Because the vents can be closed, PSDs also can save energy in the summer. Using these recommendations can reduced annual energy consumption 30%.

Abstract:Our objective is to develop a method to quantify lowconcentration metformin hydrochloride in beagle dog plasma using High Performance Liquid Chromatography(HPLC). HPLC is conducted on a Dikma Diamonsil C18 (150 mm×4.6 mm, 5μm) with acetonitrile-10.0 mmol/L sodium dihydrogen phosphate (7.5 mmol/L SDS, pH5.5)(32:68) as a mobile phase, column temperature 30℃, detection wavelength 235 nm, and flow rate 1.0 mL/min. The internal standard method is used. The results show that the identified characteristics of metformin hydrochloride and the internal standard are distinct. The regression equation is Y =0.686 8X +(-0022 2) r=0.999 5 and the linear range is 0.05~4.0 μg/L. The recovery rates are within 9978%~107.90%. The intraprecision RSD is less than 3.85%, and the interprecision is less than 563%. The developed method is sensitive, accurate, rapid and simple, and can be adopted to determine lowconcentration metformin hydrochloride in beagle dog plasma and in pharmacokinetic study.

Abstract:The effects of magnesium stress on the growth and photosynthetic character of cucumber seedlings are studied at various temperatures using artificial climate box. This is done to investigate the functional mechanism of magnesium in cucumbers. The results show that at low temperature, magnesium stress evidently inhibits plant growth, while at suitable temperatures it decreases the plant diameter, total number of leaves, leaf area, and dry weight of the aboveground parts, and increases the plant height and root/shoot ratio. Excessive magnesium promotes belowground cucumber growth. The value of chlorphyl A/chlorophyl B (Chla/Chlb) increases more under conditions of magnesium deficiency than under magnesium excess. The Chla, Chlb and Cxc content decreases when magnesium is deficient, increase when excessive magnesium exists at suitable temperatures, but decreases if excessive magnesium exists at low temperatures. Pn and Gs decrease under magnesium stress, and are at the lowest level when excessive magnesium exists at low temperatures. The effects of magnesium stress on Ci, WUE, Tr and Ls vary at different magnesium concentrations and temperatures. The main factor limiting photosynthesis of cucumber seedlings is nonstomata factor when magnesium is deficient, but is a stomata factor if there is excessive magnesium.

Abstract:Six haptens of pyrethrins are synthesized by preparing carboxyl of a ketone group of fivemembered rings．Six complete antigens are made by conjugating haptens to Bovine serum albumin (BSA) using a carbodiimide method．Ultraviolet spectrophotometry is used to demonstrate that the molecule conjugation ratios of Pyrethrin I-II, Cinerin I-II, and Jasmolin I-II to BSA are 6∶1, 13∶1, 9∶1, 11∶1, 7∶1, and 9∶1, respectively．The complete antigens are used as immunogens to immunize BALB/c mice to prepare antiserum．The antibody titers exceed 105 when measured using indirect enzymelinked immunoassay (ELISA). The polyclonal antibodies against pyrethrins are obtained via saturated ammonium sulfate precipitation．This research is may improve enzymelinked antibody detection and immunosorbent assay of pyrethrins．

Abstract:The effects of an αolefin polymer drag reduction agent (DRA) created using solution polymerization on the efficiency of drag reduction are studied. The results show that αolefin polymer DRA begins to reduce drag when the concentration is 5 mg/L. Up to a constant value, the drag reduction percentage of the samples improves as the concentration increases. The drag reduction percentage drops rapidly as shearing times increase. The effects of polymer characteristics on drag reduction efficiency are further studied. Particle density and concentration are obtained through viscosimetry. The results show that with αolefin polymer DRA, the characteristic viscosity is lower, density is higher, particle concentration is lower, and molecular weight is higher resulting in improved drag reduction efficiency. Other conditions worsen drag reduction efficiency.