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The Resonance Suppression for Parallel Photovoltaic Grid-connected Inverters in Weak Grid

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International Journal of Automation and computing 2018年第6期15卷 716-727页

作者： Qiu-Xia Yang Kun Li cui-mei Zhao Hu Wang School of Electrical Engineering Yanshan University

Obvious resonance peak will be generated when parallel photovoltaic grid-connected inverters are connected to the weak grid with high grid impedance, which seriously affects the stability of grid-connected operation of the photovoltaic system. To overcome the problems mentioned above, the mathematical model of the parallel photovoltaic inverters is established. Several factors including the impact of the reference current of the grid-connected inverter, the grid voltage interference and the current disturbance between the photovoltaic inverters in parallel with the grid-connected inverters are analyzed. The grid impedance and the LCL filter of the photovoltaic inverter system are found to be the key elements which lead to existence of resonance peak. This paper presents the branch voltage and current double feedback suppression method under the premise of not changing the topological structure of the photovoltaic inverter, which effectively handles the resonance peak, weakens the harmonic content of the grid current of the photovoltaic grid-connected inverter and the voltage at the point of common coupling, and improves the stability of the parallel operation of the photovoltaic grid-connected inverters in weak grid. At last, the simulation model is established to verify the reliability of this suppression method.

关键词： Parallel photovoltaic grid-connected inverters weak grid grid impedance resonance peak branch voltage and current double feedback.

Scaffolds for central nervous system tissue engineering

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Frontiers of Materials Science 2012年第1期6卷 1-25页

作者： Jin HE Xiu-mei WANG Myron SPECTOR Fu-Zhai cui Institute for Regenerative Medicine and Biomimetic Materials State Key Laboratory of New Ceramics and Fine ProcessingDepartment of Materials Science and EngineeringTsinghua UniversityBeijing 100084China Orthopedic Research Laboratory Brigham and Women's HospitalHarvard Medical SchoolBostonMA 02115USA

Traumatic injuries to the brain and spinal cord of the central nervous system （CNS） lead to severe and permanent neurological deficits and to date there is no universally accepted treatment. Owing to the profound impact, extensive studies have been carried out aiming at reducing inflammatory responses and overcoming the inhibitory environment in the CNS after injury so as to enhance regeneration. Artificial scaffolds may provide a suitable environment for axonal regeneration and functional recovery, and are of particular importance in cases in which the injury has resulted in a cavitary defect. In this review we discuss development of scaffolds for CNS tissue engineering, focusing on mechanism of CNS injuries, various biomaterials that have been used in studies, and current strategies for designing and fabricating scaffolds.

关键词： central nervous system (CNS) tissue engineering scaffold hydrogel

Eco-compensation of Wetlands in Yellow River Delta of Shandong Province,China

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Chinese Geographical Science 2012年第1期22卷 119-126页

作者： HAN mei cui Jinlong HAO Zhen WANG Yi WANG Renqing College of Life Science Shandong University Jinan 250100 China College of Population Resource and Environment Shandong Normal University Jinan 250014 China School of Economies Nankai University Tianjin 300071 China

Wetlands play an important ecological role and provide many functions for people, yet wetlands are cur- rently decreasing and deteriorating. The ability to calculate an economic value for the loss of wetlands is becoming in- creasingly important for policy makers. In this study, remote sensing, field investigations, department visits, and other methods were used to survey wetland types, assess wetland area changes, and calculate wetland economic value. Mar- ket value loss and ecological ftmction value loss, caused by reduction of wetland area and environmental pollution were calculated using commonly accepted methods of market valuation, ecological valuation, environmental protection investment cost analysis, and outcome parameters. According to market value loss and ecological function value loss, preliminarily fund allocation for wetland and ecological compensation was calculated. This will provide an important reference for future Yellow River Delta eco-compensation studies.

关键词： Yellow River Delta wetland eco-compensation compensation standard

CRLB analysis of wireless cognitive location with different short-range measurements

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The Journal of China Universities of Posts and Telecommunications 2008年第2期15卷 1-6页

作者： cui Qi-mei LIU Jun TAO Xiao-feng ZHANG Ping Key Laboratoryof Universal Wireless Communications Beijing University of Posts and Telecommunications Beijing 100876 China

Because of the wide application and great market potential of location-aware services, the research of wireless location techniques for the fourth generation （4G） mobile communications is being paid more attention. Wireless cognitive location （WCL） techniques for next generation wireless networks have been proposed in recent years. This article investigates the changes of the positioning accuracy of WCL algorithm when different methods are adopted to measure the short-range （SR） information. By fJrst completing Cramer-Rao lower bound （CRLB） analysis of the WCL algorithm with SR measurements based on time of arrival （TOA） and received signal strength （RSS）, it is discovered that TOA-based or time difference of arrival （TDOA） -based SR measurement can make WCL algorithms achieve higher accuracy than RSS mode, which is also verified by numerical simulation in the article. The conclusions can instruct the design of novel WCL-based location algorithms.

关键词： wireless cognitive location short range (SR) longrange (LR) Cramer-Rao lower bound (CRLB)

Polyaspartic acid mediates the absorption and translocation of mineral elements in tomato seedlings under combined copper and cadmium stress

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Journal of Integrative Agriculture 2019年第5期18卷 1130-1137页

作者： HU mei-mei DOU Qiao-hui cui Xiu-min LOU Yan-hong ZHUGE Yu-ping National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources/College of Resource and Environment Shandong Agricultural University

Polyaspartic acid(PASP)is a nontoxic,biodegradable,environmentally friendly polymer and is widely used as a fertilizer synergist in agricultural *** many old orchards and vegetable gardens,highly fertile soil is often accompanied by severe heavy metal *** present study was designed to investigate mineral element interactions mediated by PASP under copper(Cu)+cadmium(Cd)combined stress to provide reasonable suggestions for scientific fertilization.A pot experiment was conducted in which tomato seedlings served as plant materials.A concentration of 700 mgPASP and foliar spraying application methods were selected based on previous *** treatments were applied:normal soil(control(CK)),Cu+Cd(combined stress),Cu+Cd+PASP,and normal soil+*** plant biomass,root activity,and mineral elements were measured,and these data were analyzed by Data Processing System(DPS)statistical *** results showed that,under Cu+Cd combined stress,PASP promoted stem diameter growth,root activity and chlorophyll content and ultimately increased the biomass of tomato seedlings to different ***,the content of both Cu and Cd and their individual accumulation in plants *** increased the distribution of Cu and Cd in the roots under Cu+Cd combined stress,and the translocation ability from the roots to shoots was significantly *** respect to essential elements,PASP promoted mainly the absorption and translocation of potassium(K),calcium(Ca),and magnesium(Mg),which greatly exerted physiological ***,the variation trends of Cu and Cd under normal soil conditions contrasted with those under stress *** respect to essential elements other than K,Ca,and Mg,PASP mostly restrained their absorption but promoted their *** regulatory mechanism of PASP differed between the combined stress conditions and normal soil *** the combined stress conditions,PASP seemed to mainly promote these

关键词： tomato seedlings polyaspartic acid Cu+Cd combined stress

Power allocation in cooperative MIMO systems under individual power constraints

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The Journal of China Universities of Posts and Telecommunications 2011年第5期18卷 1-6页

作者： YANG Shan cui Qi-mei XU Yue-qiao LUO Yuan Key Laboratory of Universal Wireless Communications Ministry of Education Beijing University of Posts and Telecommunications Beijing 100876 China

allocation （PA） plays an important role in capacity improvement for cooperative multiple-input multipleoutput （Co-MIMO） systems. Many contributions consider a total power constraint （TPC） on the sum of transmit power from all nodes in addressing PA problem. However, in practical implementations, each transmit node is equipped with its own power amplifier and is limited by individual power constraint （IPC）. Hence these PA methods under TPC are not realizable in practical systems. Meanwhile, the PA problem under IPC is essential, but it has not been studied. This paper extends the traditional non-cooperative water-filling PA algorithm to IPC-based Co-MIMO systems. Moreover, the PA matrix is derived based on the compound channel matrix from all the cooperative nodes to the user. Therefore, the cooperative gain of the IPC-based Co-MIMO systems is fully exploited, and further the maximal instantaneous capacity is achieved. Numerical simulations validate that, under the same IPC conditions, the proposed PA scheme considerably outperforms the non-cooperative water-filling PA and uniform PA design in terms of ergodic capacity.

关键词： power allocation cooperative MIMO individual power constraint ergodic capacity

Single and joint stress of acetochlor and Pb on three agricultural crops in northeast China

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Journal of Environmental Sciences 2007年第6期19卷 719-724页

作者： CHAO Lei ZHOU Qi-xing CHEN SU cui Shuang WANG mei-e Key Laboratory of Terrestrial Ecological Process Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China The Graduate School of Chinese Academy of Sciences Beijing 100039 China College of Environmental Science and Engineering Nankai University lianjin 300071 China

In order to evaluate ecological risk of agrochemicals in agricultural environment, single and joint toxic effects of an important herbicide and a typical heavy metal on root elongation of crops were investigated. Seeds of the three crops including wheat （Triticum aestivum）, Chinese cabbage （Brassica pekimensis） and soybean （Glycine max） as the main crops in northeast China were exposed to acetochior as a herbicide and lead （Pb） as a heavy metal using the pot-culture method, and meadow brown soil as one of the main soils distributed in northeast China was applied in the investigation. The results indicated that the interactive effects of the two pollutants on root elongation of the three crops were very complicated although they had markedly significant （P〈0.01） linear interrelationships based on the regression analyses. When the concentration of added Pb^2＋ reached 200 mg/kg, acetochlor and Pb had an antagonistic effect on the inhibition of root elongation of the three crops. However, acetochlor and Pb had significantly （P〈0.05） synergic effects on the inhibition of root elongation when concentration of added Pb^2＋ was up to 1000 mg/kg. At the low concentration of added Pb, joint toxicity of acetochlor and Pb was more dependent on the concentration of Pb. Among the three crops, wheat was the most sensitive to the toxicity of Pb and Chinese cabbage was the most sensitive to the toxicity of acetochlor.

关键词： acetochlor Pb ecotoxicology joint effect Chinese cabbage (Brassica pekimensis) soybean (Glycine max) wheat (Triticum aestivum)

Ischemic colitis after receiving the second dose of a COVID-19 inactivated vaccine: A case report

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World Journal of Clinical Cases 2022年第12期10卷 3866-3871页

作者： mei-Hua cui Xiao-Lin Hou Jun-Yuan Liu Department of Gastroenterology Aerospace Center HospitalBeijing 100049China

BACKGROUND The outbreak of the coronavirus disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2 has been the most important clinical challenge worldwide since January ***-19 inactivated vaccines play a crucial role in reducing the rates of morbidity and *** SUMMARY We presented a 48-year-old woman from Haidian District,Beijing,China who developed ischemic colitis after receiving the second dose of COVID-19 inactivated *** tomography of the abdomen showed edema and bowel wall thickening with hypodensity in the sigmoid colon and descending *** revealed hyperemia,edema and erosion of the mucosa with superficial ulceration and a yellow-white coating at the descending colon and sigmoid *** symptoms were relieved after 1 wk of receiving pinaverium bromide(50 mg,tid)and aspirin enteric-coated tablets(0.1 g,qd).CONCLUSION The possible occurrence of ischemic colitis should be considered after administration of the COVID-19 inactivated vaccines.

关键词： COVID-19 Vaccine Ischemic colitis Adverse event Case report

The effect of hydrogen peroxide on properties of Ce0.35Zr0.55La0.055Pr0.045O2 oxides and the catalytic performance usedon Pd supported three-way catalyst

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Journal of Rare Earths 2017年第11期35卷 1092-1101页

作者： Qi wang meisheng cui Xiaowei Huang Yongke Hou mei Yue Qiang Zhong YongqiZhang General Research Institute for Non-Ferrous Metals Beijing 100088 China Grirem Advanced Materials Co. Ltd Beijing 100088 China

In this study,two series of cerium zirconium mixed oxides CeZrLaPrOwere prepared under traditional co-precipitation and oxidation co-precipitation methods respectively. The physicochemical properties of the samples were compared under these two methods and assessed by XRD,Raman,BET,TEM,HTPR,OSC,XPS and catalysts measurements. The formation of homogeneity phase structure can be facilitated by changing the precipitating properties of Ce3+ under oxidation coprecipitation method, which is helpful to enhance the homogeneity of Ce and Zr at atomic ***’s more, it is conducive to remove impurities Na~+ and Cl~-by oxidation co-precipitation with hydrogen peroxide. The catalysts activities are related to both the redox properties and the textural properties of mixed oxides. The Pd-only TWCs supported on the CZLP-H-F exhibits better catalytic performance and thermal stability with wider air/fuel ratio operation window, lower light-off and full conversion temperatures of CHand NO. The homogeneity of phase structure for cerium zirconium mixed oxide can be predicted and deduced from detecting the atomic distribution uniformity of its precursor. So this work not only provides insights into the mechanisms for phase segregation of cerium zirconium mixed oxide, but also provides a guidance to improve homogeneity of cerium zirconium mixed oxide by adding additives.

关键词： Cerium zirconium mixed oxides Co-precipitation Hydrogen peroxide Catalytic performance