Search

In order to enhance ships' security and stable energy efficiency,there are new challenges about the means on power quality assessment improvement of marine electric system. This paper analyzed the importance to the ship’s safety for quality of electricity,and discussed present situations about the question of poor power quality in marine electric system; moreover,especially proposed reasonable means on power quality assessment and more effective and practical means on improvement of marine electric system,through massive studies the experiment repeatedly using the mature control theory and computer simulation technology,as well as instance of three-phase harmonic filter for controlling harmonic distortion,based on the Matlab simulation software to establish the 12 pulse (AC - DC) converter simulation model; finally emphasized the future research directions and prospects of the electric utilization and marine engineering technology development.These important means may promote energy conservation and reliability enhancement to more deeply research on power quality assessment improvement of marine electric system.

The Rumei core wall rockfill dam hydropower station is in Lancang River in the Mangkang county of the Tibet autonomous region with maximum height of 315m and crest length of 666.2m. Due to the high core wall rockfill dam has been more than 300m high, water level sudden drawdown of the unsteady seepage condition shall be taken into consideration, according to the given water level drop speed (5m/d) calculate condition, analysis of the seepage field distribution of the different water level, free surface of different time, each material partition of the dam and foundation soil seepage gradient, etc are given. The results showed that the free surface of the upstream dam shell rockfill body dropping fast than the water level dropping speed of the reservoir. The seepage gradient of the upstream shell is very small, which will not cause adverse effect on the upstream dam slope stability. The free surface of the downstream dam shell rockfill body changes little, which will not cause adverse effect on the downstream of the dam slope stability. As the water level falls, the free surface of the core wall dropping speed is slow, far less than the water dropping speed of the reservoir. In the process of emptying reservoir, the free surface of the core wall remains in a high position, which should cause enough attention.

The risks of air conditioning system were found out by analyzing safety accident in recent years, and the derivative and secondary disasters were identified about air conditioning system. On the basis of the theory of man-machine-environment-management of system safety analysis, the risk index system of the possibility and consequences severity was established by identifying the possibility and the consequence severity factors resulting in the occurrence of air conditioning. The risk grades were determined by using the risk matrix to conduct the risk assessment for air conditioning system of a Commercial building in Tianjin. The preventive measures and control safety measures were proposed for air conditioning system Security.

This paper results the tension of putting thread machine by analyzing and calculating the polarization grid technology requirements; uses CATIA and ANSYS Workbench to build a three-dimensional solid model and analyze the static characteristics and provides a reliable reference In order to improve the structure of put thread machine.

This paper presents the results of a study regarding the relationship between temperature and power load of the electric power system. Weather-influenced load part is picked up from original load series data with the conclusion that the lagged effect of temperature on load is within 12 hours. Furthermore, decision tree and step regression methods are employed to get a group of decision trees and corresponding regression equations which are able to quantitatively describe the relationship between load and temperature. A short-term load forecasting algorithm is then developed and its practical implementation shows this quatitative analysis method could reliably reflect the influence of the temperature changes on the load and effectively improve the accuracy of short-term load forecasting.

In the paper, energy storage system and charge and discharge control strategy for large-scale photovoltaic generation are designed. The optimal energy storage capacity is configurated for PV array. The energy storage system and control module for PV generation are built in MATLAB-Simulink platform. Supercapacitor (SC) is the energy storage element. Considering the insolation and temperature under the changing meteorological conditions, the output power would be fluctuant. By controlling MOSFET switches based on power signal, SC will charge when the lighting is adequate and discharge in the instance of lack of light to keep DC bus voltage in constant. Configuring the optimal energy storage capacity by simulation, the result proves that the control strategy is feasible and the configuration is optimal.

PV (Photovoltaic) generation output with MPPT (Maximum power point tracking) is unadjustable. In this paper, PV generation is expected to regulate grid frequency. Thus a power tracking control strategy based on feedback frequency instead of MPPT is put forward. The feedback frequency is transferred to controlling unit of DC-DC inverter. The DC bus voltage is adjusted by controlling the duty cycle of DC-DC invertor. A grid-connected PV system with a power tracking control strategy based on feedback frequency and a DC-AC inverter control module are built in MATLAB-Simulink platform. Experiment result indicates that PV generation could regulate grid frequency by the control strategy based on feedback frequency.

Coal consumption characteristics data provided by on-line monitoring system are crucial for Energy-saving generation dispatching. Therefore contrastive tests are required for checking the accuracy of the coal consumption on-line monitoring system. In the paper, factors affecting coal consumption characteristics data were analyzed, methods and contents of the contrastive tests were also achieved. By comparing three test conditions with the base condition, computing program, measuring points, manual inputting data and other influencing factors were checked. This tests could provide accurate coal consumption characteristics data. This study has been applied successfully in many plant units, and the formation of local standard in Guizhou Province, China.

Juglone is isolated from many plant species belonging to Juglandaceae family. Recent studies have shown that Juglone exhibits various bioactivities including anti-tumor functions. However, its anti-cancer activity on human ovarian cancer SKOV3 cell has not been examined. Thus, the current study was designed to elucidate the effect of Juglone on migration of human ovarian cancer SKOV3 cells. In the present study, SKOV3 cells were incubated with Juglone at various concentrations. Wound healing assay and Transwell chambers were used to detect migration of SKOV3 treated with Juglone for 24h. The result showed that Juglone inhibited the migration of SKOV3 cells with concentration of Juglone at 25, 50 or 100μM compared with control cells. Therefore, our results indicated that Juglone may be a potential candidate of drug for ovarian cancer.

An intelligent module is design for monitoring air pipeline pressure on ship. The project is proposed adopting DSP as control core and employing redundant CAN bus to ensure the data transmission reliability. The key solution such as power supply, signal conditioning and communication are introduced in detail. The intelligent diagnosis and communication protocol are also discussed in the end.

A bacterial strain S5-1capable of degrading chlorimuron-ethyl was isolated from paddy soil using enrichment technique. On the basis of traditional culture characteristics, colony and cell morphology, physiological and biochemical characteristics, type of internal photosynthetic membrane and combined with 16S rRNA gene sequence analysis, the strain was identified as aRhodopseudomonassp.. The optimal temperature and pH for biodegradation of chlorimuron-ethyl byRhodopseudomonassp. strain S5-1were 35°Cand pH 7.0, and the degradation rate reached 87.8% within 10 days under the optimal conditions. The results revealed that strain S5-1could degrade chlorimuron-ethyl efficiently and for further study it could potentially be used as a biological agent for the remediation of soil, water or crops, contaminated by chlorimuron-ethyl herbicide.

This paper investigates the feasibility of MA600 reduced-power take-off by finding the necessary conditions which reduced-power take-off must satisfy based on the performance characteristics and actual flight data of MA600 turboprop aircraft. Finally, we come to the conclusion that reduced-power take-off of MA600 aircraft can be achieved.

This paper aims to study the root activity of wheat and radish seeds with seven plant growth regulators in room through seed soaking. The results show that it mainly affects the stem height of wheat seed when it was 1000 dilution of the 7 plant growth regulators, but it mainly affects the main root length of wheat seed when it was 5000 dilution. when we treat radish seeds in 1000 and 5000 dilution , there were obvious effect on stem height and main root length, this study is helpful for field planting.

A method based on Gabor filter bank is presented to automatically detect the steel cord conveyor belt fault. Firstly, multi-channel filtering is implemented by Gabor filters. Then the characteristic differential and fusion images are calculated. Finally, the fault images are identified by white pixels statistics after the threshold segmentation. The results show that this method has good detection result for steel cord conveyor belt fault.

This paper evaluated module performance deterioration based on module performance baselines, and established a case-based aero-engine module maintenance level decision model. Then corrected the module maintenance level based on the limits of LLP, AD/SB, hardware damages, soft time to develop a reasonable maintenance level.

Based on the high-speed photography, the effect of phase relations on droplet transfer and welding seam was analyzed. To each TCGMAW (Twin-wire Co-pool Gas-shielded Metal Arc Welding) torch at four-wire welding robot, under the descriptive welding parameters, when the phase relation of the front wire and the back wire was alternate, the arcs of the two wires had no effect on each other basically; the welding seam shaped very well. When the phase relation was synchronized, the arcs attracted each other and the two arcs centralized to the middle of the two wires; the humping bead was formed. When the phase relation was random, now and then the arcs synchronized and attracted each other, and at times the arcs changed alternately and had no effect on each other; the appearance quality of the welding seam was moderate.

Composite roughness is an important parameter in river hydraulic calculations. In this paper, various typical methods for predicting composite roughness of river were summarized, including Einstein Method, Lotter Method, JIANG Method and Weighted Average Method, their theoretical rigors were discussed from both perspectives of minimum energy dissipation principle and analytical analysis, and their calculation precisions were verified by a large number of flume test data. Research shows that Einstein Method complies with the principle of minimum energy dissipation, also is the necessary and sufficient condition of resistance equation having unique solution, and its calculation precision is higher, therefore, Einstein Method is more suitable for composite resistance calculation of river with single cross section.

The basic faults detection logic of fuel flow metering valve can not detect all the faults. It may cause un-commanded in-flight shut-down (IFSD) on the aero-engine and threat the flight safety. The operation principle of fuel flow metering valve is introduced in this paper. The basic faults detection logic is given. Two IFSD examples are presented. To reduce the un-commanded IFSD, faults detection logic updating is discussed. It can be used to design the new control software of the aero-engine and improve the aero-engine’s reliability.

The effect of the interface states on the properties of (p+) a-Si:H/(n) c-Si heterojunction solar cells is studied by a set of simulations. The results show that there is almost no effect on the short-circuit current. At very low interface states, there is almost no effect on the open-circuit voltage VOC and the fill factor FF, and then the conversion efficiency. Although, at high interface states, VOC decreases due to the decrease of the excess minority carrier density at the c-Si neutral region and the increase of the effective interface recombination velocity at the heterojucntion interface, which also results in the decrease of FF. In particular, at very high interface states, the hole transport is limited by the interface potential barrier, which results in S-shaped J–V characteristics and low fill factors. As a result, the conversion efficiency decreases with interface states increasing at high interface states.

The high pressure turbine clearance control valve (HPTACCV) fuel leakage on CFM56-5B engine can cause some flight delays and cancellations. The basic structure of HPTACCV is introduced. The root cause of the fuel leakage is given. In the field, to provide a more reliable engine, Weibull Analysis can be used to determine the soft time. This paper presents how to use Weibull Distribution to calculate the soft time life and forecast the spare parts equipments. This method can be used to evaluate the other failures of the aero engine components.

Nanometer α-nickel hydroxide codoped with Cu and Al has been synthesized by the ultrasonic-assisted precipitation method. The crystal structure and particle size were analyzed by X-ray diffraction (XRD) and particle size distribution (PSD). The electrochemical performance of the samples was characterized by the charge/discharge test and cyclic voltammetry. The results of electrochemical tests demonstrated that the specific discharge capacity of Cu/Al codoped α-nickel hydroxide (330 mAh/g) is much higher than that of pure spherical nickel (240 mAh/g), and it exhibits a relatively good electrochemical reaction reversibility and large proton diffusion coefficient.

The aim of web-based 3D visualization of monitoring over materials haulage to rock-fill dam is to achieve 3D visual expression on internet for transporting vehicles and the surroundings, which is hydropower project construction site layout. On the basis of analysis on 3D visualization process based on 3DS MAX and principles of web-based 3D visualization based on ActiveX technology, the implementation scheme of web-based 3D visualization of monitoring over materials haulage to dam is designed and its implementation methods are analyzed in detail. The real-time motoring and analysis system of materials haulage to rock-fill dam with network, digitalization and visualization, which is developed in B/S architecture, provides supports to engineering construction management.

The hydraulic characteristics of curved channel flow are one of the most important subjects to hydraulic researchers and engineers. Among them the magnitude of circulation velocity and its calculation method is of great interests. Experimentation of generalized curved channel was carried out to explore the flow velocity parameters and circulation velocity characteristics by adopting the ADV to measure and analyze the 3D velocity datum. Theoretic formula was established for calculating the circulating velocity in the curved channel. Comparison with the results calculated from the formulas of other researchers the formula proposed in the paper is relatively quite good. The paper provides a basis to explore the hydraulic characteristics of the curved channel profoundly.

The traditional algorithm of searching a new radio signal is not from the nature of the signal, but from the simple statistics and four arithmetic operation. So, there must be a big gap to decide which signal is a abnormal signal. This paper draws the innate character of the signal and then uses the ordered weighted averaging aggregation operators (OWA) and k-means to deal with the datum. The signal type is decided by multiple attribute decision making (MADM). The result of experiment show the method is effective.

An improved project based on double thresholds method in noisy environments is proposed for robust endpoints detection. Firstly, in this method, the distribution of zero crossing rate (ZCR) on the preprocessed signal is taken into account, and then the speech signal is divided into different parts to obtain appropriate thresholds with decision trees on the basis of the ZCR distribution. Finally, the double thresholds method, focusing on different importance of the energy and ZCR, is taken in the corresponding situation to determine the input segment is speech or non-speech. Simulation results indicate that the proposed method with decision trees obtains more accurate data than the traditional double thresholds method.

This article dissertated the status of classification to desulfurization agent CaCO3, designed a kind of new-type whirlpool grader, dissertated the principle and excellence of its impeller, at last we established its math model.

In the light of Information Island phenomenon existing in the current police system and inadequate excavation of data, this paper advances the necessity of establishing police intelligence data warehouse system. Vs.net 2008 and SQL Server 2008 are used to design and implement the police intelligence data warehouse system, and more over probes deeply into the technology of ETL.

In order to improve the dispersion performance of nano-C60 crystals, the surface metallization was achieved by electro less nickel plating; By the laser-induced way, a new composite coating was got on a micromechanical device, which contained some metalized nano-C60 crystals. Research on the fretting friction and wear behavior of the composite coating, its ability of Wear Resistance were improved evidently.

Magnetic catalyst was made of magnetic core and surface coating layer and obtained a core-shell complex materials. The magnetic γ-Fe2O3 core has a relatively higher saturation magnetization, coercivity and good thermal stability even at 500°C. In order to prevent magnetic core forming spinel structure and migrating of Fe3+, a layer of silicon dioxide was coated by sol-gel method. During the process iron atoms scattered in –Si-O-Si- network and produced a γ-Fe2O3@SiO2 structure. Finally, the γ-Fe2O3@SiO2 powder was put into the alumina sol and evenly sprayed into a column of oil, after calcination the carrier of alumina layer was prepared.

For the high cost, poor nano-size controlling and the complex technology in the existing Preparation of nano-materials, Gas-Powder Mixed Spark Discharge Reaction (GPMSGR) was used for the preparation of nano-powders. Nano-powders, average particle diameter of 100-150nm were obtained by using GPMSGR with improving the existing ordinary column type EDM machines.

In this paper, we present a fast method for segmentation of triangular meshes into simple patches. The method is suitable for commonly used CAD models. Given a mesh surface, all faces of it cluster to a user-specified number of patches according to similarity of curvatures. Experimental results show that our algorithm is very efficient and effective.

This paper has summarized the current ranking method for interval-valued intuitionistic fuzzy numbers, and then through the introduction of decision-makers’ mentality indicator, presented a new ranking method for interval-valued intuitionistic fuzzy numbers based on mentality function. Not only the nature of mentality function is deeply discussed but also the decision-making model based on the interval-valued intuitionistic fuzzy numbers is constructed. At last, an example is illustrated to prove the model's accuracy and effectiveness.

Due to the popularity of knowledge discovery and data mining, in practice as well as among academic and corporate professionals, association rule mining is receiving increasing attention. The technology of data mining is applied in analyzing data in databases. This paper puts forward a new method which is suit to design the distributed databases.

In this paper, the influences of different binders (Hydroxypropyl Methyl Cellulose (HPMC), Carboxymethyl Cellulose Sodium (CMC), Polytetrafluoroethylene (PTFE) and Styrene- butadiene Rubber (SBR)) on high-rate discharge performances at low temperature for the negative electrode of Ni/MH battery have been studied by orthogonal experimental design. Electrochemical measurements have been conducted to investigate the capacity, charge-discharge performance, cyclic voltammetry and electrochemical impedance characteristics. The surface morphology and chemical compositions have been investigated by SEM and EDS. Based on the range analysis, the primary and secondary influence factors as well as the optimization results were obtained. From the CV characteristic curves, the oxidization peaks and reduction peaks are not clearly shown, which indicates that the redox reaction does not occur clearly after binders added. The EIS experiments show that the deterioration of the voltage characteristic of the battery is due to drying out of the separator that increases the ohmic resistance (Rs ), and the decay of the discharge capacity is due to the passivity surface that increases the charge-transfer resistance (Rt) of the battery.