bluuebunny/crossref_metadata_2025 huggingface dataset:
The Synthesis and Properties of the Modified Bentonite-Starch Absorbent Polymer
Authors: Sun Rui Jian , Li Meng Yao , Zhang Jin Chi , Zhu Li Jun
Published: August 2013

The composite absorbent polymer was synthesized by the solution polymerization method with acrylic acid, starch and bentonite as raw materials, N, N-methylene-bis-acrylamide as cross-linking agent, and ammonium persulphate as initiator. The whole process was under nitrogen protection. Factors including amount of starch, crosslinker, initiator, monomer, and neutralization degree and reaction temperature were investigated in terms of their influences on water absorbency. Effect of bentonite amount on polymer strength and water absorption rate was also tested. The modified polymer, with the composition of 10% corn starch, 0.15% initiator, 0.05% crosslinking agent and 8% bentonite, showed a significant strength enhancement at 65°C and 80% neutralization degree (molar ratio) with water absorption of 1012g/g in deionized water and 92g/g in 0.9% NaCl solution.
Pilot Scale Evaluation of Pellet Fluidized Bed Process for the Conditioning of Alum Sludge
Authors: Zhang Gang , Zhang Li Qing
Published: August 2013

As a burgeoning technology based on conventional clarifier technology, pellet fluidized bed (PFB) technology has been widely applied in kinds of high SS water treatment process. In this paper, PFB process was used to thicken the alum sludge in a water plant in south China with scale of 1.0~2.5m3/h. The experimental results showed that, increasing flocculent (PAM) dosage could decrease outlet turbidity, and average up pellets settling behavior. Under the experimental condition, there exist negatively linear relationship between process maximum flow rate which ranged from 1.6m3/h to 2.2 m3/h and raw sludge concentration. Moreover, because of the improvement of pH environment and flocs chemical structure, additional lime dosage would enhance maximum surface loading and save PAM dosage. The pilot scale experiment proved that by applying PFB, alum sludge conditioning could achieve satisfied results characterised by high surface loading, low outlet turbidity, and high concentration thicken sludge with fine dewaterability.
Chronic Effect of Cadmium on Serum Concentrations of Estradiol and Testosterone in Male Rana nigromaculata
Authors: Huang Min Yi , Duan Ren Yan , Kong Xiao Quan , Zhu Hai Yan
Published: August 2013

The adult maleRana nigromaculatawere exposed to different doses of cadmium for 30d, serum concentrations of the steroid hormones, testosterone and estradiol were examined. Chronic exposure to cadmium caused significant changes both at the testosterone and estradiol levels. Exposure to cadmium resulted in lesser serum testosterone concentrations and more estradiol in 0.05 and 0.1 ppm. Although not statistically significant, frogs exposed to 0.2 ppm had smaller drop in testosterone and significant more estradiol. The results suggest that cadmium exhibited the non-monotonic dose-response relationship with the serum hormone concentrations, testosterone and estradiol.
Study on Xylanase-Aided Bleaching of Wheat Straw KP
Authors: Zhao Li Jun , Niu Mei Hong , Zhang Jian , Sun Yan Ning , Li Na
Published: August 2013

Before oxygen bleaching and hydrogen peroxide bleaching, wheat straw pulp was bleached using xylanase. The effect of enzymatic stage on pulp properties and bleachability has been studied and compared with reference (control) pulps, processed without enzyme addition. Experimental results showed that, the optimal concentration of wheat straw pulp was 10%, the optimal treatment time and dose of enzyme was 60 min and 1.25AXU/g respectively. Oxygen pressure decreased from 0.6MPa to 0.5MPa when conditions of hydrogen peroxide bleachingremained unchanged and wheat straw pulp achieved the same whiteness. Hydrogen peroxide consumption decreased from 2% to 1.8% when oxygen bleaching has the same conditions and achieved the same white degree.
Study on Inhibitory Effect of Wheat Stalk on Algae by Different Treatments
Authors: Liao Ri Hong , Xu Zhi Lan , He Xu Wen , Hu Xiu Lin
Published: August 2013

This paper reports the effects of wheat stalk anaerobic extract and wheat stalk powder on the inhibition ofMicrocystis aeruginosain the laboratory, and the broken wheat stalk on the growth of the phytoplankton and zooplankton in natural water. The results show that: (1) the Wheat stalk Anaerobic extract has inhibitory effect on theMicrocystis aeruginosa, the average inhibiting rate was 59%; (2) the Wheat stalk powder has obvious inhibitory effect on theMicrocystis aeruginosa, the average inhibitory rate was 74% and the effect increased with the passage of time. The inhibitory rate remained the range of 75%~96% from the 3rd day to 13th day after adding the Wheat stalk powder; (3) In natural water, the addition of broken wheat stalk can cause change of the dominant phytoplankton species in which cyanophyte is not obvious dominant species anymore, and the broken wheat stalk has inhibitory effect on the growth of phytoplankton cells; (4) The addition of broken wheat stalk can promote the growth of poor-middle nutrition species zooplankton in natural water, and make their abundance soars rapidly.
Adsorption Behaviors of Oxytetracycline on Synthetic Resins
Authors: Wang Meng Qiao , Liu Xiao Han , Wu Liu Yan , Li Ai Min
Published: August 2013

Three commercial resins (NDA150, NDA88 and NDA77) with different physicochemical properties were selected to investigate the adsorption behavior and primary factors controlling the adsorption of oxytetracycline (OTC) onto the resins. The adsorption kinetics of OTC onto all resins were fitted well to pseudo-second-order model. NDA150 had the largest adsorption capacity due to its higher surface area and larger total pore volume. Moreover, all of the three resins exhibited nearly the same equilibrium time because of their nearly the same particle size. The suitable pH for the effective adsorption of NDA150 and NDA77 is from 4 to 7, while the ideal pH for NDA88 is 10. OTC adsorption on all of the three resins increased with the increasing ionic concentration.
Studies on Mechanical and Chemical Property Changes of Environmental Degradation Polyethylene Mulching Film Immersed in Water Environment
Authors: Zhao Bin Bin , Luo Xue Gang , Lin Xiao Yan , Zhang Hong Ping
Published: August 2013

This research studied the effects of the water environment on the mechanical, chemical and morphological changes of environmental degradation polyethylene mulching film. The mechanical characteristics of the environmental degradation polyethylene mulching film immersed in water environment or exposed in air declined. The elongation at break retention of the sample immersed in water reached minimum value for 70 days while 40 days for sample exposed in air. FTIR showed new hydroxyl absorption band appeared at 1717cm-1after exposed for 60 days. The relative intensity of absorption band of sample exposed in air is higher than sample immersed in water. AFM images showed large fluctuation on the surface after immersed in water or exposed in air for 60days.
Zeolites P1 Formation by Hydrothermal Alkali Fusion of Coal Fly Ash
Authors: Zhang Feng Xia , Yang Bin , Ma Ming Yu , Sun Shu Hong
Published: August 2013

Fly ash is produced from the combustion of powdered coal and used to synthesize zeolite by alkali fusion followed by hydrothermal treatment with stirring. By varying the experimental conditions different types of zeolite were produced. In this study, mixture of sodium hydroxide and fly ash in a pre-determined ratio, was milled and fused at 700°C for 1h.The resultant fused mixture added to water in a Teflon reaction vessel and incubated at a temperature of 100°C and autogenously pressure. At the end, the reaction products recovered by filtration. The synthesized zeolite was characterized using various techniques such as X-ray diffraction, scanning electron microscopy. The zeolite-P1 was tested for decontamination potential of mine water. High removal efficiency was observed in the first treatment, but varied for different contaminants. The synthesised zeolite-P1 exhibited a high efficiency for the removal of heavy metal cations, such as zinc, copper, lead and cadmium from contaminated mine water.
Effect of Annealing on Photocatalytic Performance of BiOCL Nanosheets
Authors: Cui Zhan Kui , Mi Li Wei , Zheng Zhi , Wang Guang Hui , Fa Wen Jun
Published: August 2013

BiOCl nanosheets were annealed at different temperatures. The effect of annealing on structures and properties was characterized by X-ray diffraction (XRD), N2 adsorption-desorption, UV-visible diffuse reflectance spectroscopy (DRS) and photoluminescence spectroscopy (PL). The photocatalytic performance was evaluated by photodegrading Rhodamine B (RhB) under UV light irradiation. It was found oxygen vacancy defects (OVDs) could be generated during the annealing treatment and the best photocatalytic efficiency was obtained when the annealing temperature was 450 °C. The enhanced photocatalytic efficiency was ascribed to the high separation efficiency of the photogenerated electron-hole pairs due to the existence of the OVDs as positively charged centers.
Preparation and Characterization of CNT/C Composite Membranes from 6FAPB-PMDA Type Polyimide
Authors: Zhang Bing , Shi Yi , Wu Yong Hong , Lu Yun Hua , Wang Tong Hua
Published: August 2013

A novel precursor, 6FAPB-PMDA type polyimide, was developed to prepare carbon membranes and carbon nanotube (CNT) composite carbon membranes. The thermal stability of precursors was characterized by TGA. The morphology of carbon membrane was observed by SEM. The microstructure was measured by XRD and nitrogen adsorption technique. Results have shown that 6FAPB-PMDA type polyimide is a promising precursor, and the introduction of CNT can obviously modify the thermal stability, as well as the carbon and porous structure of resultant carbon membranes.
Application of Extenics in Evaluation of Risk of Dam
Authors: Shi Yong Chao , Cao Ai Wu , Wang Jin
Published: August 2013

According to the extension of matter element, a quantitative evaluation model of dam risk analysis of multiple parameters is developed. Matter-element model was constructed to assess dam behavior by matter-element transform. The emergency capacity besides safety of dam and failure losses is taken into concerned during the analysis of risk of dam. Finally, a simple example shows that is more reasonable compared with traditional methods.
Optimizational Model of Transmission of Infectious Disease SARS
Authors: Liu Wen Bin
Published: August 2013

SARS is first worldwide transmitting infectious disease of the 21st Century.In this paper,we set a model of differential equation about transmission of infectious disease SARS. Three parameters simply describe transmitting law of SARS. Then, we forecast epidemic situation, and analyze sensitivity .Finally we analyze that SARS affect tourism.
Research and Application of Mobile Gas-Extraction Technology on the Upper Corner of Working Face
Authors: Hua Ming Guo , Yu Zhen Jiang , Lei Bo Wei
Published: August 2013

Aiming at solving the existing problems of gas treatments on the upper corner presently,poor drainage effect and the high cost of engineering quantity included , gas drag pipe drainage technology and processes on the upper corner is designed.It can make the drainage point matching working face advance speed, realize continuous drainage points in space.And research on the drainage parameters is the foundation of the successful implementation of drag drainage pipe technology.It introduced Brinkman equation, Fick's law of diffusion and gas diffusion translational equations to describe the behavior of gas flow diffusion ,established the migration and diffusion gas flow model at working face ,and the two models are combined in a unified flow field., establishing a coupling model of multi-physics gas flow at the working face.And the model is solved by fluent to determine the optimal parameters of towing pipe drainage.Finally,it makes a practical application and testing results in Changcun coal mine working face N3-8. The results show that gas drag pipe drainage technology is conducing to governing on the accumulation of corner gas,and the gas concentration on the upper corner down to 1%,determining the best the drainage location for distance back plane 2.4m, an inclined direction distance back to the wind tunnel 1.6m, along strike depth to goaf 15m .Taking measures to block the upper corner,which can improve the drainage concentration,and make the concentration of gas on the upper corner down to 0.6%.The application of field basically agrees with the simulation results,so pipe drainage technology has feasibility and good applicability of top corner gas drag
River Eco-Environmental Challenges during Urbanization Process Lesson Learned from Beijing Rainstorm on July 21st
Authors: Jiang Yun , Chen Fan
Published: August 2013

During the process of urbanization, impermeable surface areas enlarge and rain runoff and peak discharges grow, rainstorm become more frequent. As more rain water and pollutants mixed with each other, more areas of urban runoff are polluted, causing significant change to aquatic organisms, especially fish, their population and structure. In order to balance the relations between urban development and river eco-environmental protection, avoid reappearance of mega rainstorm disaster like the one on July 21st in Beijing, we suggest protecting and safeguarding the structure and function of urban river ecological system from perspectives of urban planning, eco-environment improvement and integrated management over urban river system.
Velocity Calculation of Lahar in Changbai Mountain Region
Authors: Sheng Jian , Wang Yu Meng , Lv Han , Yang Qing Fu
Published: August 2013

Lahar as one of most serious volcanic hazards, threats peoples lives and property securities of volcanic region. Velocity is the most important parameter for lahar hazard assessment and prevention. The calculation result of lahar velocity can provide reference materials for making hazard prevention plan, and make the hazard relief measure of lahar transition from passive to active. Selected the area near the Tianchi as the research region, and divided the research region into forming region, circulation region and accumulation region. In order to establish the calculation model, divided the circulation region and accumulation region into many meshes, which were small enough to meet the calculation accuracy. The calculation time step length was also identified very small as 0.001 min. Calculated the average and peak velocity of lahar, triggered by the assuming medium and small eruption of Tianchi volcano. The longitudinal variation of lahar frontal average and peak velocity was acquired by the numerical simulation result. Although there is some different between the assumption of this research and the actual condition, flow velocity and accumulation situation of lahar are calculated in quantity and extension by numerical simulation, these result has reference value for preventing and reducing lahar disaster.
Long-Term Probability Prediction on the Extreme Sea States Induced by Typhoon of the South China Sea
Authors: Pang Liang , Chen Xuan , Li Yu Long
Published: August 2013

The sea state of the South China Sea is influenced by tropical cyclone obviously. It is important to carry out the long-term prediction and probability analysis of typhoon wind, wave height and wave period for the coastal and offshore engineering. In this paper the measured wind and wave data during typhoon processes from 1964-1989 are used to predict the long-term extreme sea states by using Grey Markov Chain Model. And the joint probability analysis of extreme wave height with concomitant wave period and wind speed is performed by using Multivariate Compound Extreme Distribution model which involves typhoon occurrence frequency and corresponding joint probability distribution of typhoon induced extreme sea environmental events. The proposed model shows that the mean value of typhoon occurring frequency per year plays the significant role in long term prediction of typhoon induced joint return values of extreme sea events.
Assessing Human Carcinogenic Risk of Heavy Metal Exposure in a Tourist Area
Authors: Yang Hong , Wang Min , Dong Xiao Ya
Published: August 2013

Environmental safety in a tourism area is one of the basic security for tourists health. Thus, it is of great significance to assess the heavy metal-based potential health risk of a tourism area and its surrounding areas. This study mapped the carcinogenic risk of heavy metal polluted soil in a tourism area of XX City through procedures including on-site sampling, exposure dose estimation, toxicity assessment, carcinogenic risk calculation, and GIS (Geographic Information System) spatial interpolation. Results show that the soil of the tourism area was contaminated by heavy metals such as As, Cd. The maximum Cd concentration in soil was 41.60 times more than the second level of Soil Environmental Quality Standard of China (SEQSC). Meanwhile, the carcinogenic risk of heavy metal polluted soil is much higher than the international acceptable limits (i.e. 1.0E-06) with maximum risk value at 148.7E-06. Source contribution analysis also disclosed that the carcinogenic risk in the tourism area is mainly attributed to As. It therefore can be concluded that As and Cd polluted soil in the tourism area of XX City needs to be recovered immediately in order to protect tourists health.
Distribution of Exchangeable Ca and Mg in the Soil Environment of Yunnan Plateau
Authors: Wang Ai Guo , Wang Wen , Hu Chen Cheng , Li Qin , He Zhong Jun
Published: August 2013

Ca and Mg in soil are essential nutrient elements for plants, and their exchangeable state is mainly effective. This paper studied the characteristic of statistics, distribution and exchangeable Ca/Mg for Chinese herbs plantation base soil of Yunnan Baiyao Group Co.LTD. The results of 214 soil samplings data show that 93.55% soil samplings of exchangeable Ca content were above 800 mg/kg, so the Baiyao base soil was rich in Ca element. 79.44% of the samples were seriously potential Mg deficiency. The moderate exchangeable Ca/Mg (between 5 and 10) accounts for 41.1%. Baiyao base soil with higher exchangeable Ca and Mg mainly distributed in southwest and north parts, and exchangeable Mg content in the southeast corner was also higher.
Effect of the Change of Nitrite Content in Natural Fermentation on the Edible Security of Chinese Sauerkraut
Authors: Du Shu , Wu Jun Rui , Sun Xin , Yue Xi Qing
Published: August 2013

During the course of fermentation of Chinese sauerkraut, it would produce nitrite. However, the presence of nitrite made Chinese sauerkraut cause edible security problem. In this study, the change regularity of nitrite during natural fermentation was analysed, and the best edible time was determined. The results showed that content of nitrite was increased in the early stage of fermentation, after reaching to a peaking content, it reduced significantly to a low level, and then it changed little at the mature stage. That is to say, it could guarantee the edible security when Chinese sauerkraut matured.
Numerical Simulation of the Dust Suppression with Forced Ventilation Shunt Mode in Fully Mechanized Workface
Authors: Meng Jun , Jiang Zhen Jun , Zhang Miao Miao , Qin Yue Ping
Published: August 2013

Based on fluid mechanics, the theory of gas-solid flow and jet theory etc. Dust migration regularity in fully mechanized workface was studied and simulated under far-pressing-near-suction ventilation with FLUENT Simulation technology. When the ratio of blowing to suction (μ) is larger than 1, the range of high dust concentration reduces and the maximum dust concentration decreases. The sketch of flow field of the different μ, the short of traditional far-pressing-near-suction ventilation and the superiority in practical of dust removal mode with the forced ventilation shunt were summarized and analyzed. The dust migration regularity in different shunt parameters (K) in this mode was simulated. Increasing shunted air quantities (Q) is beneficial to the control of dust diffusion in the roadway. But dust concentration near pressure air side will increase if the value of the shunted air quantities is over a critical value.
The Impact of Heat Waves on Mortality in Nanjing Area from 2004 to 2010
Authors: Jing Yuan Shu , Zhang Di , Yan Min Fei , Tan Jian Guo
Published: August 2013

This paper analyzed the excess mortality change in nine districts of Nanjing city, based on mortality data and meteorological data from 2004 to 2010. Taken a typical heat waves process in summer of 2006 as an example, it was discussed of the effect of the heat process on different gender, different age groups , and various disease death toll and excess mortality changes. The excess mortality was associated with the average maximum temperature and average minimum temperature during the heat waves. Excess mortality occurred in the middle of June heat wave when excess mortality was much higher than in other time periods. In late June, early July to early August, the excess mortality is relatively small. The average daily deaths are increasing with increasing age for male and female, and every age death numbers is higher than that with no heat waves during the heat wave period. In addition to the respiratory system diseases, diseases of the genitourinary system, other diseases, residual disease in the heat waves has increased, and diseases of the nervous system and the endocrine system diseases of excess mortality rate reached a staggering 342.93% and 119.63%, accounting for almost half of the total heat excess mortality. The heat waves effect is very obvious. The conclusion is of great significance for prevention of high temperature heat harm.
Effect of Oil Water-Accommodated Fraction on Growth and Chlorophyll-A of Marine Microalgae
Authors: Zhang Yu Bai , Tang Xue Xi
Published: August 2013

The experiment studied the 96h acute toxicity effects on three kinds of microalgae caused by Water-Accommodated Fraction (WAF), and effects of different concentrations WAF (Platymonas helgolandicavar.tsingtaoensis,Nitzschia closteriumf.minutissima00.524816 mg/L;Isochrysis galbana00.52.551020 mg/L) on chlorophyll-a content and chlorophyll fluorescence parameters. It showed that the WAF 96h EC50of thePlatymonas helgolandicavar.tsingtaoensis,Nitzschia closteriumf.minutissima,Isochrysis galbanawere 13.84mg/L, 18.83mg/L and 6.73mg/L. The level of WAF sensitivity wasNitzschia closteriumf.minutissima>Platymonas helgolandicavar.tsingtaoensis>Isochrysis galbana. The WAF caused inhibition of chlorophyll-a content except in condition of the low concentration. It showed the higher of the WAF concentration, the stronger the inhibition.
Study on Plant Oxygen Generating and Oxygen Concentration Detection Technology for Plateau
Authors: Wang Wei Jun , Wang Peng Wei
Published: August 2013

In order to solve the hypoxia problem of the people living in plateau, this article took plants oxygen generating to supply oxygen-enrich air for them based on the research of the main oxygen generator method, and designed plant oxygen generating system and the oxygen concentration detection system. Practice has proved that the plant oxygen generating system can provide the oxygen-enriched air and the oxygen concentration detecting system can get the real-time acquisition of oxygen concentration data quickly and high accuracy.
Ecological Impact Assessment on the China's Ice Storm in 2008
Authors: Zhou Ben Zhi , Cao Yong Hui , Wang Xiao Ming , Ge Xiao Gai
Published: August 2013

An unprecedented ice storm occurred in south China in early 2008, bringing extensive damages and huge losses to human beings and natural ecosystems. By site specific survey, coupled with review of the government documents and reports, we made an ecological impact assessment on the ice storm. 19 provinces were attacked with a population of over 100 million affected. The ice storm caused extensive damage to vegetation, crops, wildlife and insects. A total forestland of 19.4 million hectares impacted, with 340 million m3 standing volume lost. The ecological service of the forests considerably impaired, with the capacity of the water and soil conservation, water resources conservancy and carbon sequestration weakened largely. An area of 14.32 million hectares crops were impacted, with oilseed rape, vegetable and fruit severely damaged. 30,000 wild animals under special state protection were died or injured due to the storm, and distribution and population density of some insects were impacted.
Cooperated Control Strategy of DFIG Wind Power Generation System under Unbalanced Grid Condition
Authors: Deng Ya , Hu Shu Ju , Meng Yan Feng , Xu Hong Hua
Published: August 2013

This paper proposes a cooperated control of the grid side converter (GSC) and rotor side converter (RSC) in doubly-fed induction generator (DFIG) wind power generation system under unbalanced grid condition. Mathematical model of doubly-fed induction generator (DFIG) and GSC under unbalanced grid voltage condition are investigated. Dual-dq current control strategies of the RSC and GSC under unbalanced grid condition are detailed studied. A cooperated control strategy of the GSC and RSC under unbalanced grid condition is proposed to provide enhance operation of DFIG system. The GSC is controlled to remove the total active power fluctuation of the system and RSC is controlled to eliminate the DFIG electromagnetic torque oscillation. Simulation based on Matlab/Simulink of a 1.5 MW DFIG prototype was carried out to validate the proposed cooperated control strategy.
Comparison of Borehole Thermal Resistance Values of Ground Heat Exchanger Obtained by Several Methods
Authors: Kang Han Byul , Yoon Seok , Go Gyu Hyun , Lee Seung Rae
Published: August 2013

The Ground-Coupled or Source Heat Pump (GCHP/GSHP) system is increasingly being considered as an alternative to traditional cooling/heating system because it can reduce the emission of greenhouse gases. The GCHP/GSHP system uses sustainable ground temperature to emit heat during the summer and to extract heat during the winter. It is a ubiquitous system because it can be used at any time or place and semi-permanent energy. The geothermal system is composed of Ground Heat Exchanger (GHE), heat pump and load facilities. The GHE is embedded in a borehole, which is made up of GHE and grout. The borehole thermal resistance is the most important parameter in designing the geothermal system because it shows the quantity of heat transfer in the borehole. There are many methods to estimate the borehole thermal resistance. Thermal Performance Tests (TPTs) were conducted to directly measure the borehole thermal resistance of several kinds of GHEs. Then the experiment results and analytical results were compared in order to select the most accurate methods to evaluate the borehole thermal resistance.
Transient Stability Assessment of Power System Using Support Vector Machine with Generator Phase Plane Trajectory Inputs
Authors: Wang Ke , You Da Hai , Long Cheng , Chen Wei Hua , Wang Gang
Published: August 2013

Transient stability assessment (TSA) is part of dynamic stability assessment of power systems, which involves the assessment of the systems ability to remain synchronism under credible disturbances. Recent research shows that transient stability status of a power system following a large disturbance such as a fault can be early predicted based on phase plane trajectories of generator variables. Based on this, a binary support vector machine (SVM) classifier with generator phase plane trajectory inputs was trained to predict the transient stability status. In order to find the best trajectory inputs, three different types of phase plane trajectories were designed. By investigating effectiveness of the three trajectories with New England 39-bus test system, classifiers with phase plane trajectories of electromagnetic power as inputs achieved better predictions than other two types of trajectories. The highest accuracy achieved by the classifier with inputs of electromagnetic power phase plane trajectories is 99.336% which can meet requirements of practical application.
Pitch Control for Smoothing Doubly Fed Induction Generator Rotor-Side Power Fluctuations
Authors: Tian Qiang , Wang Xiao Lan
Published: August 2013

Dramatic wind speed variations result in the fluctuations of output power in DFIG. This paper presents a pitch control to suppress DFIG Rotor-side active power fluctuations. Though pitch angle changes too quickly could result in generator power fluctuations, the pitch control adopts PID controller and an angle rate limiter to prevent rapid pitch angle changes. The pitch control strategy is simulated by Matlab simulation platform, and the results have shown the correctness and validity of the pitch control.
The Influence of Motor Low Voltage Trip on under-Frequency Load Shedding in the Electric Network of Refinery Enterprise
Authors: Han Tian Zhen , Yang Qi , Song Yun Ting , Tang Xiao Jun , Guo Qing Kui , Yuan Yong Yu , Sun Jian Jun
Published: August 2013

A simple frequency response model is generally used in UFLS (under-frequency load shedding) design, without considering the impact of voltage on the frequency. In fact, in the case of large active and reactive shortage power, the system will suffer from the low voltage problem by the emergence of low frequency, which easily leads a large number of motors tripping due to low voltage protection trip in the UFLS process. The influence on UFLS is compared and problems needed to solve are put forward.
The Novel Control Technologies Used in Permanent Magnet Synchronous Motor
Authors: Zhang Jun Li , Li Yu Ren , Xie Li Li
Published: August 2013

In order to improve the torque control performance of permanent magnet synchronous motor, variable frequency variable speed control technology, vector control technology, direct torque control technology and sensorless control technology were analyzed. The fuzzy + PID control technology used in permanent magnetic synchronous motor was introduced in detail. The conventional sliding mode observer based on the counter electromotive force estimate control technology and the structure of improved sliding mode observer was given separately. The fuzzy + PID control technology and improved sliding mode observer control technology proposed could improve the dynamic performance and static performance of the permanent magnet synchronous motor.
Energy Scavenging Device Based on Electric Field in Substations
Authors: Li Hong Wei , Yu Chun Hui , Zhang Li
Published: August 2013

Wireless sensor network has many advantages while energy supplying is a main limit. However, energy scavenging technology affords an efficient solution, especially in high voltage substations, there is swarmed with strong electromagnetic field, and the scavenging device based on electric field has an irreplaceable advantage. An equivalent mathematical model of the converter was established to study the energy harvesting effect. Another model of conditioning circuitry was further built to analyze the factors affecting charging current. Finally, several main factors and corresponding methods are analyzed to improve the energy scavenging efficiency.
Numerical Analysis of Hot Ends Length Effect on the Performance of Energy Separation in Vortex Tube
Authors: Wu Zhong Ye , Fang Xiang Jun , Sun Wen Long
Published: August 2013

In this paper, effects of the vortex tube hot end lengths on the performance are studied, using a three-dimensional numerical fluid dynamic model. The hot end and cold end structure of vortex tube adapts the conical tube with the dilated side connecting a straight pipe. Structural mesh is employed. Different turbulence models are used, compared with experiment, considered of convergence and computing time, eventually, SST model is applied. In contrast to experimental data, numerical results are acceptable. By numerical analysis, it is observed that as the length of hot ends increases, the performance of energy separation increases significantly. However, while the length diameter ratio is more than 20, the performance does not increase any more. Even, it begins to decrease. Meanwhile, different hot end lengths flow is compared, and attemptable analysis is conducted to the flow phenomenon.
Unified Controller Design for Two-Stage Converter Based on Feed-Forward Compensation
Authors: Xia Tao , Yuan Zhi Chang , Li Yong Xing , Guo Hai Feng , Zhang Bai Hua
Published: August 2013

A unified control structure for two-stage power converter system (PCS) is proposed which incorporates both charging and discharging modes within the same controller. Detailed modeling process is presented using sub-system approach. Power feed-forward compensation with direct battery current reference is engaged to enable fast response to power change on battery side, thus reducing DC bus voltage fluctuation during transients. Simulation and experiments show that the proposed control structure can effectively improve dynamic response without compromising steady-state performance.
Efficiency Evaluation Model of Power Transmission & Transformation Project Investment Based on AHP-Fuzzy Method
Authors: Tian Gui Shen , Liu Ji Cheng , Zhou Jing Jing , Liu Jun Li , Li Bing
Published: August 2013

This article builds an efficiency evaluation model. Using AHP method, an evaluation indicator system is established, and the weights of the indicators are calculated. This paper applies Fuzzy Evaluation method to determine the membership function of qualitative and quantitative indicators, and then synthesizes the indicator weights and the evaluation matrix to get the fuzzy comprehensive evaluation result. Finally, a case of a certain power transmission & transformation project is studied, and the comprehensive evaluation result of its economic benefit is moderate.
Substation Optimization Planning Considering Distributed Generation
Authors: Liu Zi Fa , Liu Gang , Zhang Wei
Published: August 2013

This paper established a transformer substation comprehensive optimal planning model considering distribution generation (DG) and different block geographic information factors (GIF), set form, volume, location of existing DG in planning area and transformer substation load-bearing capacity as constraint condition, taking construction cost of distribution transform substation and feeder and operation cost including current supply loss into account, in the meantime, regarding the influence of GIF such as land properties and so on to location and cost of construction with load demand satisfied. Furthermore, influence factors of different block information factor to construction cost were work out by means of interval analytical hierarchy process. On the basis of the established objective function, an particle swarm optimization (PSO) algorithm is proposed to solve the problem in this paper. By empirical study of certain planning area, the proposed model and algorithm are proved to be scientific and effective.
Numerical Simulation of O2/CO2 Pulverized Coal in 300MW Boiler
Authors: Li Li Li , Qu Chao
Published: August 2013

O2/CO2combustion technology is an effective method to capture and store coal-fired boiler flue gas CO2. With a 300MW subcritical pulverized coal boiler as the research subject investigated, Fluent numerical simulation software is used to simulate the process of pulverized coal combustion both in air and O2/CO2conditions. The comparative analyses are made both in the former conditions, such as the combustion characteristics of pulverized coal, the influence of oxygen volume fraction, the effect of the secondary air temperature on the temperature field in the furnace of pulverized coal boiler. As for the following results of the pulverized coal combusted in the O2/CO2condition, compared with the results in the air condition, its time of ignition is delayed, and the combustion temperature is low and the central position of flame rises. With the increasing percentage of the oxygen volume and the rising temperature of secondary air, the time of ignition speeds up, which improves the overall furnace temperature level and transferring capability of the radiation heat.
Analysis and Control on Oscillation Characteristics of Smart Grid with Large-Scale Wind Power Integration
Authors: Zhong Jia Chen , Liu Wen Ying , Zheng Wei
Published: August 2013

To deal with the problem of large-scale wind power integration and its influence on low frequency oscillation characteristics of Gansu power network, this paper built the low frequency oscillation simulation model with large amount of wind power integration, and proposed an index, namely grid structural weakness degree, based on the damping ratio index, to investigate low frequency oscillation characteristics. The simulation shows that the damping ratio decreases as the wind turbine output increases; and when the damping ratio is lower than 3%, or weakness degree lower than 4, it is more likely to cause low frequency oscillation in Gansu power network, and early-warning should be taken. The analysis provides a reference for low frequency oscillation early-warning and control.
Analysis on Guarantee Strategies of Reliability for Hengqin Power System
Authors: Chen Hui , Zheng Wen Jie , Zheng Ya Ru
Published: August 2013

In this paper, reliability guarantee strategies for Hengqin were proposed based on reliability affecting factor system and Hengqin needs of high reliability power system and smart grid, and the reliability enhancing degree of these strategies were assessed. Firstly, the indices of reliability were analyzed, and the reliability affecting factor system was built up. Then, combined with the development need of Hengqin power system, four specific reliability guarantee strategies-network structure construction, advanced distribution automation, intelligent operation and maintenance center and the end-line monitoring system-were proposed and the reliability effects were quantitatively assessed. Finally, the reliability effect of the strategies was compared with the reliability goal of Hengqin power system, and the adequacy and completeness of the strategies were verified.
Decoupling Droop Control Method for Power Distribution of Microgrid
Authors: Yang Shi Wang , Li Peng , Wang Chang , Li Jia Ming
Published: August 2013

How to ensure the security, stability and economic operation of microgrid in different operation modes is a difficult problem of microgrid research. There is active power and reactive power coupling in the regulation of frequencies and voltages because of the line parameter characteristics of microgrid. The defect of the traditional active power-frequency, reactive power-voltage droop control is analyzed and a novel decoupling droop control method for low voltage microgrid is proposed in this paper. At last, the multiple feedback loop control strategy for inverters on the basis of this proposed method and a microgrid simulation model are established. The comparative analysis between the new method and the traditional method based on the simulation results can prove that the proposed control method is simple in design, and it can assure an excellent power quality and realize the reasonable distribution of active power and reactive power between distributed generations.
Design and Implementation of Microgrid SCADA Platform
Authors: Shen Zi Qi , Deng Wei , Pei Wei , Mu Lian Shun , Ouyang Hong
Published: August 2013

Microgrid and traditional power system are different in terms of operation and control. SCADA reliability directly affects the operational control capacity of the microgrid. Based on the actual needs of the microgrid operation control and energy management, the author designed microgrid SCADA platform, including architecture, information exchange mechanism and data services, and then developed actual microgrid SCADA test platform. Through long-time test, the SCADA platform could achieve reliable microgrid operation and management.
Smart Grid in China: A Review
Authors: Shen Jia Kun , Zhao Chang Hong , Yuan Jia Hai
Published: August 2013

With the acceleration of economic development, the development of the power system is facing greater challenges to meet this challenge, the concept of smart grid is able to generate. This article provides an overview about the motivation for developing smart grid of the major countries in the world. Then it provides a review about the development and the relevant policies about smart grid in China. It also described the planning and roadmaps by Power Grid Companies, analyzed the problems of domestic smart grid development briefly and gave recommendations about what should be focused on in the future.
Modal Sensitivity Analysis for Parallel Harmonic Resonance in Power System
Authors: Yang Cai Xia , Liu Kai Pei , Zheng Xue , Wang Dong Xu
Published: August 2013

Parallel harmonic resonance is closely related to the singularity of a node admittance matrix. It was found that the smallest eigenvalue of the matrix defines the mode of parallel harmonic resonance. This paper applies eigenvalue theory and modal sensitivity analysis method to determine which network components contribute significantly to a harmonic resonance phenomenon. Case study results further confirm the theoretical correctness and effectiveness. Thus, this practical method not only provides significant measures for harmonic resonance manage, but also support theoretical and experimental bases for the component parameter design.
Design and Analysis of Distributed Pump-System in District Heating Network
Authors: Jiao Jing , Wang Hai , Wang Hai Ying
Published: August 2013

This paper presents a new scheme of distributed pump-system for district heating network. As no circulating pumps for the heat sources and no throttle valves for the users, much energy is saved. And the control of hydraulic parameters can be adjusted without interfering with that of the thermodynamic parameters. The novel scheme is available for both looped pipeline networks (LPNs) with multiple heat sources and dendritic pipeline networks (DPNs) with single heat source. Moreover, for users located at the hydraulic intersection points of the looped pipe network with multi-heat sources, their water temperature can be less affected by their own water consumption. A case study was presented and about 22% power saved when the new scheme was employed.
Research of Vacuum Degree Influence on Performance of Vacuum Heat Insulation Oil Pipe
Authors: Wang Zhong Hua , Zhao Hai Qian
Published: August 2013

In this paper, mathematical model for heat transfer in thermal barrier is established based on the experiment which tested apparent heat conductivity of heat insulation oil pipes. Vacuum degree influence on performance of vacuum heat insulation oil pipe is analyzed by contrasting heat insulation oil pipes in different grades. The main conclusions are as follow. When internal pressure in the thermal barrier is between 0~20Pa or greater than 40Pa, the apparent heat conductivity increases with the pressure. And when internal pressure in the thermal barrier is between 20~40Pa, the apparent heat conductivity decreases with the pressure in volatility. When internal pressure in the thermal barrier is between 30~40Pa, the apparent heat conductivity of heat insulation oil pipe is lesser.
Experimental Investigation of Methane/Air Penetration Combustion and Flame Stability Characteristics on Porous Wall Surface
Authors: Zheng Xiao Feng , Feng Yaoxun , Jia Ming Sheng
Published: August 2013

Aimed to optimize the design of micro combustor whose chamber based on porous medium wall surface, combustion and flame stability characteristics on porous wall surface with methane/air flat flame were investigated experimentally in this paper. The experimental results show that stable flat flame can be formed on the porous medium surface within given ranges of fuel equivalence ratio and flow rate. When mixture flow rate increasing, the thickness of flame decreases firstly and then increases, and standoff distance of flames decreases quickly and then is unchanged. At higher mean velocity of mixture, the flame moves closer to the porous plate surface, and the minimum distance needing for keeping stable flames decreases. The heat exchange between the porous plate and the mixture can not only preheat mixture but also cool the porous plate.
Flow Patterns Identification in a High-flux Circulating Fluidized Bed with Shannon Entropy Increment Rate
Authors: Yin Shang Yi , Jin Bao Sheng , Zhong Wen Qi
Published: August 2013

Experiments of gas-solid suspension were carried out in a high-flux circulating fluidization bed with the solid mass flux up to 536 kg/(m2·s). Differential pressure fluctuation time series were obtained at different locations in the riser. Shannon entropy increment rate analysis was developed to identify the flow pattern and transformation and characterize the dynamic behavior. Effect of superficial gas velocity on the Shannon entropy increment rate was examined under high solid mass flux. It was demonstrated that a circulating fluidization bed at high solid mass flux was a deterministic chaos system and the sensitivity of the system's chaotic characteristic to operating parameters at different flow regimes was different. Shannon entropies increment rate of different flow regimes were distinct. Shannon entropy increment rate analysis method results in high degree of recognition for flow pattern and transformation.
Performance Characteristics of a Class of External Combustion Engines
Authors: Zheng Shi Yan , Yang Hui Shan
Published: August 2013

The general cycle model of a class of external combustion engines is established in which the influence of the multi-irreversibilities mainly resulting from the linear heat-loss model between the high and low heat reservoir, and the irreversible adiabatic processes. Some important parameters such as the power output, efficiency and the temperatures of the working substance are calculated and some important characteristic curves are given. The results obtained in this paper may provide some theoretical guidance for the optimal design of the Carnot, Brayton, Braysson and some new heat engines.
Thermodynamic Modeling of Air Reservoir for CAES Power Plant
Authors: Song Xiao Na , Hu Yan Ping , Zheng Jun , Li Pei , Hou Xiao Xia , Liu Wen Yi
Published: August 2013

CAES (Compressed Air Energy Storage) is an energy storage method which preserves electric energy in the form of air pressure potential energy. As the storage space, the internal air pressure of air reservoir significantly affects the performance of the CAES system. Based on a thorough study of variable pressure air reservoir of CAES, this paper puts forward a thermodynamic modeling method which could be perfectly applied in air pressure and temperature variation analysis. Modeling parameters are fitted by serving Huntorf power plant in Germany as reference case; results show that the obtained pressure curves match the actual curves, which in turn demonstrate the high accuracy of the model presented. By comparing different pressures under several working conditions, it is clear that alternately air releasing and air inflation effectively reduce throttling loss and the energy consumption of compressor, also system efficiency is improved.
Investigation and Application of Forced Cooling of WH 600MW Steam Turbine
Authors: Shi Yong Feng , Xu Jian Qun , Ma Lin
Published: August 2013

With a long natural cooling time after a shutdown of steam turbine restricting its available coefficient, this paper presented the analysis and application of a forced cooling process to sub-critical steam turbine. The radiating mechanism of natural cooling was analyzed theoretically, and the required amount of cooling air was calculated for a WH 600MW steam turbine. Moreover, the cooling rate with no life loss principle was determined by the method of quantitative calculation and numerical analysis, together with safety analysis. The research discussed the control strategy of practical application according with steam turbine characteristic and applied to operation, which provided theoretical guidance for the optimization of cooling condition.