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Search Results: 1 - 10 of 78569 matches for " Huijun Chen "
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Research on Skill Testing Standard of Marketing Major of Wuhan City Vocational College  [PDF]
Hui Li, Huijun Chen
Creative Education (CE) , 2017, DOI: 10.4236/ce.2017.82017
Abstract:
Higher vocational education scale expands rapidly in the recent years, followed by the contradiction between expansion scale and education quality, which has become increasingly prominent nowadays. In order to improve the teaching quality, the most important is to improve daily teaching activity of the harmonious combination of teaching quality monitoring and evaluation system, which focuses on the teaching quality in higher vocational colleges through monitoring and the objective requirement of the long-term quality assurance mechanism. Based on investigation and analysis of present situation, analysis of professional practice skill testing of students majoring in marketing of Wuhan City Vocational College, we develop skill-testing standard in the hope of improving students’ marketing professional skills in future.
A Cognitive Model for Recognition of Genre
Huijun Chen
Asian Social Science , 2009, DOI: 10.5539/ass.v5n3p25
Abstract: This paper discusses the cognitive process (es) in recognizing instances of genre and the effects of generic features have on recognition of genre. Following the ESP tradition, the paper takes the communicative purpose as the defining feature of a genre and follow Martin’s stratified model of language and context in for the analysis. Based on a preliminary study conducted among three geologists, this paper proposes a model revealing the cognitive process (es) in recognition of instances of genre. According to the model, the cognitive recognition of a genre basically goes from the bottom up, and the effects that the generic features have on recognition of instances of genres decrease from the top down. However, as the cognitive processes are very complicated, the top-down and bottom-up processes may sometimes interweave. Even at each stratum alone, the reader may have to experience a complicated interactive process. The schema theory is an important theory that works as a general thread throughout the model proposed. Apart from the general schema-matching processes at the beginning and the end of the whole processes, there might exist a schema-matching process at each processing stratum, too.
Joint Decoding of Concatenated VLEC and STTC System
Chen Huijun,Cao Lei
EURASIP Journal on Wireless Communications and Networking , 2008,
Abstract: We consider the decoding of wireless communication systems with both source coding in the application layer and channel coding in the physical layer for high-performance transmission over fading channels. Variable length error correcting codes (VLECs) and space time trellis codes (STTCs) are used to provide bandwidth efficient data compression as well as coding and diversity gains. At the receiver, an iterative joint source and space time decoding scheme are developed to utilize redundancy in both STTC and VLEC to improve overall decoding performance. Issues such as the inseparable systematic information in the symbol level, the asymmetric trellis structure of VLEC, and information exchange between bit and symbol domains have been considered in the maximum a posteriori probability (MAP) decoding algorithm. Simulation results indicate that the developed joint decoding scheme achieves a significant decoding gain over the separate decoding in fading channels, whether or not the channel information is perfectly known at the receiver. Furthermore, how rate allocation between STTC and VLEC affects the performance of the joint source and space-time decoder is investigated. Different systems with a fixed overall information rate are studied. It is shown that for a system with more redundancy dedicated to the source code and a higher order modulation of STTC, the joint decoding yields better performance, though with increased complexity.
Joint Decoding of Concatenated VLEC and STTC System
Huijun Chen,Lei Cao
EURASIP Journal on Wireless Communications and Networking , 2008, DOI: 10.1155/2008/890194
Abstract: We consider the decoding of wireless communication systems with both source coding in the application layer and channel coding in the physical layer for high-performance transmission over fading channels. Variable length error correcting codes (VLECs) and space time trellis codes (STTCs) are used to provide bandwidth efficient data compression as well as coding and diversity gains. At the receiver, an iterative joint source and space time decoding scheme are developed to utilize redundancy in both STTC and VLEC to improve overall decoding performance. Issues such as the inseparable systematic information in the symbol level, the asymmetric trellis structure of VLEC, and information exchange between bit and symbol domains have been considered in the maximum a posteriori probability (MAP) decoding algorithm. Simulation results indicate that the developed joint decoding scheme achieves a significant decoding gain over the separate decoding in fading channels, whether or not the channel information is perfectly known at the receiver. Furthermore, how rate allocation between STTC and VLEC affects the performance of the joint source and space-time decoder is investigated. Different systems with a fixed overall information rate are studied. It is shown that for a system with more redundancy dedicated to the source code and a higher order modulation of STTC, the joint decoding yields better performance, though with increased complexity.
Optimal ratios of the piston speeds for a finite speed endoreversible Carnot heat engine cycle
Feng, Huijun;Chen, Lingen;Sun, Fengrui;
Revista mexicana de física , 2010,
Abstract: the performance of an endoreversible carnot heat engine cycle is analyzed and optimized using the theory of finite time thermodynamics based on agrawal and menon'si model of finite speed of the piston on the four branches and curzon and ahlborn'sii model of finite rate of heat transfer. the finite speeds of the piston on the four branches are further assumed to be different, which is unlike the model of constant-speed of the piston on the four branches. the analytical formula between power and efficiency of the cycle is derived for a fixed cycle period. there exist optimal ratios of the finite piston speeds on the four branches. the effects of the temperature ratio of the heat reservoirs on the dimensionless power versus efficiency of the cycle and isothermal expansion ratio are obtained by numerical examples.
Heating load, COP, exergy loss rate, exergy output rate and ecological optimizations for a class of generalized irreversible universal heat pump cycles
Chen, Lingen;Feng, Huijun;Sun, Fengrui;
Revista mexicana de física , 2010,
Abstract: the optimal performance of a class of generalized irreversible universal steady flow heat pump cycle model, which consists of two heat-absorbing branches, two heat-releasing branches and two irreversible adiabatic branches with the losses of heat-resistance, heat leakage and internal irreversibility is analyzed by using finite time thermodynamics. the analytical formulae about heating load, coefficient of performance (cop), exergy loss rate, exergy output rate and ecological function of the universal heat pump cycle are derived. moreover, performance comparisons among maximum cop condition, a given exergy output rate condition and maximum ecological function condition are carried out by using numerical examples. it is shown that the ecological function objective is an excellent candidate objective with the ideal of an ecological and long-term goal. the effects of heat leakage and internal irreversibility on the cycle performance are discussed. the universal cycle model gives a unified description of seven heat pump cycles, and the results obtained include the performance characteristics of brayton, otto, diesel, atkinson, dual, miller and carnot heat pump cycles with the losses of heat-resistance, heat leakage and internal irreversibility.
Finite time exergoeconomic performance optimization for an irreversible universal steady flow variable-temperature heat reservoir heat pump cycle model
Huijun Feng, Lingen Chen, Fengrui Sun
International Journal of Energy and Environment , 2010,
Abstract: An irreversible universal steady flow heat pump cycle model with variable-temperature heat reservoirs and the losses of heat-resistance and internal irreversibility is established by using the theory of finite time thermodynamics. The universal heat pump cycle model consists of two heat-absorbing branches, two heat-releasing branches and two adiabatic branches. Expressions of heating load, coefficient of performance (COP) and profit rate of the universal heat pump cycle model are derived, respectively. By means of numerical calculations, heat conductance distributions between hot- and cold-side heat exchangers are optimized by taking the maximum profit rate as objective. There exist an optimal heat conductance distribution and an optimal thermal capacity rate matching between the working fluid and heat reservoirs which lead to a double maximum profit rate. The effects of internal irreversibility, total heat exchanger inventory, thermal capacity rate of the working fluid and heat capacity ratio of the heat reservoirs on the optimal finite time exergoeconomic performance of the cycle are discussed in detail. The results obtained herein include the optimal finite time exergoeconomic performances of endoreversible and irreversible, constant- and variable-temperature heat reservoir Brayton, Otto, Diesel, Atkinson, Dual, Miller and Carnot heat pump cycles.
Optimal ratios of the piston speeds for a finite speed endoreversible Carnot heat engine cycle
Huijun Feng,Lingen Chen,Fengrui Sun
Revista mexicana de física , 2010,
Abstract: Se analiza y optimiza el funcionamiento cíclico de un motor endoreversible de Carnot, utilizando la teoría termodinámica de tiempo finito basada en el modelo de Agrawal y Menon i de velocidad finita del pistón en los cuatro cilindros, y en el modelo de rapidez finita de transporte de calor de Curzon y Ahlborn ii. También se supone que las velocidades del pistón en los cuatro cilindros son diferentes. Se deduce la fórmula analítica de la potencia y la eficiencia para un período del ciclo. Resultan cocientes óptimos para las velocidades finitas del pistón en los cuatro cilindros. Se obtienen, mediante ejemplos numéricos, los efectos del cociente de temperatura de los focos térmicos sobre la potencia versus la eficiencia del ciclo y el coeficiente de dilatación isotérmica.
Heating load, COP, exergy loss rate, exergy output rate and ecological optimizations for a class of generalized irreversible universal heat pump cycles
Lingen Chen,Huijun Feng,Fengrui Sun
Revista mexicana de física , 2010,
Abstract: Se analiza el funcionamiento óptimo de una clase de modelo universal irreversible generalizado del ciclo de una bomba térmica de flujo constante, que consiste en dos ramas de absorción térmica, dos ramas de liberación de calor y dos ramas adiabáticas irreversibles con pérdidas de resistencia al calor, de salida del calor y de irrevocabilidad interna, usando la termodinámica de tiempos finitos. Se obtienen las fórmulas analíticas de la carga de calor, del coeficiente del funcionamiento (CF), del índice de pérdida de exergía, del índice de salida de exergía, así como de la función ecológica del ciclo universal de la bomba de calor. Por otra parte, se compara el funcionamiento de la condición máxima del CF dada una condición de razón de salida de exergía con la condición del máximo de la función ecológica usando ejemplos numéricos. Se demuestra que el objetivo de la función ecológica es un excelente de candidato para el ideal de una meta ecológica y de largo plazo. Se discuten los efectos del escape de calor y de la irreversibilidad interna sobre el funcionamiento del ciclo. El modelo universal del ciclo da una descripción unificada de siete ciclos de la bomba de calor, y los resultados obtenidos incluyen las características de funcionamiento de los ciclos de Brayton, de Otto, Diesel, Atkinson, Dual, Miller y Carnot para bombas térmicas con pérdidas de la resistencia al calor, del escape de calor y de irreversibilidad interna.
Correlation between platelet gelsolin levels and different types of coronary heart disease
Yue Liu,HuiJun Yin,YueRong Jiang,Mei Xue,KeJi Chen
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-011-4926-9
Abstract: Gelsolin is an important cytoskeletal protein of platelets and studies have shown a close relationship between gelsolin and cardiovascular disease. However, the role of gelsolin in the development of coronary heart disease (CHD) is unclear. In this study, we record the distribution of gelsolin in human platelets and plasma and its association with different types of CHD. This study included 114 cases, with 33 stable angina pectoris (SAP) cases, 81 acute coronary syndrome (ACS) cases—composed of 39 unstable angina pectoris (UAP) and 42 acute myocardial infarction (AMI) cases, and 31 healthy control participants. Gelsolin concentration in platelet rich plasma (PRP) and platelet poor plasma (PPP), actin filament (F-actin) and Gc-globulin of PPP were determined by enzyme-linked immunoadsorbent assay (ELISA). The fluorescence intensity of CD62p and cytoplasmic calcium ([Ca2+]i) in human platelets measured by flow cytometry. We also used turbidimetry to detect the platelet aggregation rate (PAR). We analyzed the correlation between platelet gelsolin concentration and CD62p or plasma F-actin levels among each different patient group. Compared with the control group, the gelsolin level in PRP of UAP and AMI groups increased significantly (P<0.01), while the gelsolin level in PPP of all the three patient groups decreased markedly (P<0.01), and the CD62p, PAR, [Ca2+]i of platelets, F-actin and Gc-globulin of the UAP and AMI groups increased significantly (P<0.01). Compared with the SAP group, the gelsolin level in PRP, the PAR, [Ca2+]i of platelets and CD62p of other two groups increased significantly (P<0.01), F-actin of the AMI group increased markedly (P<0.01). Platelet cytoskeleton protein dynamics vary among the different types of CHD. Platelet gelsolin levels are markedly increased and accompanied by increased platelet activity, F-actin and [Ca2+]i of ACS patients, while gelsolin levels in PPP are markedly lower. Abnormally increased platelet gelsolin levels show high positive correlation with the level of platelet activity. Therefore, platelet gelsolin might be a novel molecular marker and/or a new potential therapeutic target of anti-platelet therapy of ACS.
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