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Search Results: 1 - 10 of 150329 matches for " Yang Zhang "
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Study of Integral Variable Structure Control Method for Stability of SI Engine Idling Speed  [PDF]
Yang Zhang, Nobuo Kurihara
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.38094
Abstract: The intake air control system of a gasoline engine is a typical nonlinear system, and included among the adverse fac-tors that always induce poor idle-speed control stability are dead time and disturbances in the intake air control process. In this paper, to improve the responsiveness when idling with regard to disturbances, a mean-value engine model (MVEM) with dead time was constructed as the control object, and the two servo structures of sliding mode control (SMC) were studied for better idle control performance, especially in transient process of speed change. The simulation results confirmed that under the constraint condition of control input, the robustness of idle speed control that is being subjected to torque disturbances and noise disturbances can be greatly improved by use of the servo structure II.
An Examination of the Effects of Aerosol ChemicalComposition and Size on Radiative Properties of Multi-Component Aerosols  [PDF]
Shaocai Yu, Yang Zhang
Atmospheric and Climate Sciences (ACS) , 2011, DOI: 10.4236/acs.2011.12003
Abstract: The sensitivity of aerosol radiative properties (i.e., scattering coefficient, extinction coefficient, single scatter albedo, and asymmetry factor) and radiation transmission to aerosol composition, size distributions, and relative humidity (RH) is examined in this paper. Mie calculations and radiation calculations using a tropospheric visible radiation model are performed. The aerosol systems considered include inorganic and organic ions (e.g., Cl-, Br-, , , Na+, , K+, Ca2+, Mg2+, HCOO-, CH3COO-, CH3CH2COO-, CH3COCOO-, OOCCOO2-, MSA1-), and (2) water-insoluble inorganic and organic compounds e.g., (black carbon, n-alkanes, SiO2, Al2O3, Fe2O3 and other organic compounds). The partial molar refraction method and the volume-average method are used to calculate the real and imaginary parts of refractive index of real aerosols, respectively. The sensitivity simulations show that extinction coefficient increases by 70% when RH varies from 0 to 80%. Both extinction coefficient and asymmetry factor increase by ~48% when real part varies from 1.40 to 1.65. Scattering coefficient and single scattering albedo decrease by 18% and 24%, respectively, when the imaginary part varies from –0.005 to –0.1. Scattering and extinction coefficients increase by factors of 118 and 123, respectively, when the geometric mean radius varies from 0.05 to 0.3 ?m. Scattering and extinction coefficients and asymmetry factor increase by factors of 389, 334, and 5.4, respectively, when geometric standard deviation varies from 1.2 to 3.0. The sensitivity simulations using a tropospheric visible radiation model show that the radiation transmission is very sensitive to the change in geometric mean radius and standard deviation; other factors are insignificant.
A Study of Multi-Node and Dual-Hop Collaborative Communication Performance Based on Harmonic Mean Method  [PDF]
Tingting YANG, Shufang ZHANG
Communications and Network (CN) , 2009, DOI: 10.4236/cn.2009.11006
Abstract: Closed form expressions for the PDF and MGF of the harmonic mean of two independent exponential variates are cited and derived, and then applied to study the performance of cellular multi-node and dual-hop cooperative communication systems with non-regenerative relays over flat Rayleigh fading channels. We derive the probability density function (PDF) and asymptotic symbol error rate (SER) expression with MRC scheme. Then we use Matlab to simulate the performance.
Research on Application of ZigBee Technology in Flammable and Explosive Environment  [PDF]
Yang Li, Ke Zhang
Wireless Sensor Network (WSN) , 2010, DOI: 10.4236/wsn.2010.26058
Abstract: Wireless Sensor Network based on ZigBee technology is a wireless network which is composed of many nodes of ZigBee RF chips, sensors and MCUs, especially suitable for application of the remote monitoring system in flammable and explosive environments. This paper presents the characteristics and advantages of ZigBee technology, also discusses the system for hardware and software design. This system effectively fulfills the remote monitoring in flammable and explosive environments and posses high practical values.
Complex Dynamics Analysis for Cournot Game with Bounded Rationality in Power Market  [PDF]
Hongming Yang, Yongxi Zhang
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2009, DOI: 10.4236/jemaa.2009.11009
Abstract: In order to accurately simulate the game behaviors of the market participants with bounded rationality, a new dynamic Cournot game model of power market considering the constraints of transmission network is proposed in this paper. The model is represented by a discrete differential equations embedded with the maximization problem of the social benefit of market. The Nash equilibrium and its stability in a duopoly game are quantitatively analyzed. It is found that there are different Nash equilibriums with different market parameters corresponding to different operating conditions of power network, i.e., congestion and non-congestion, and even in some cases there is not Nash equilibrium at all. The market dynamic behaviors are numerically simulated, in which the periodic or chaotic behaviors are focused when the market parameters are beyond the stability region of Nash equilibrium.
Structural Change Modeling of Singapore Private Housing Price in Simultaneous Equation Model  [PDF]
Weihong Huang, Yang Zhang
Journal of Financial Risk Management (JFRM) , 2012, DOI: 10.4236/jfrm.2012.12002
Abstract: This paper investigates the structural change behavior of Singapore’s private housing market and in particular the impact of government policies on housing price determination. A structural model of price is established and the “Regressive Segmentation (RS)” method is applied to detect the changing points without prior knowledge of the structural changes. Our study shows that the changing points indicated by the RS method are consistent with the timing of the policy changes.
Application, Evaluation, and Process Analysis of the US EPA’s 2002 Multiple-Pollutant Air Quality Modeling Platform  [PDF]
Kai Wang, Yang Zhang
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.23025
Abstract: A multiple-pollutant version of CMAQ v4.6 (i.e., CMAQ-MP) has been applied by the US EPA over continental US in 2002 to demonstrate the model’s capability in reproducing the long-term trends of ambient criteria and hazardous air pollutants (CAPs and HAPs, respectively) in support of regulatory analysis for air quality management. In this study, a comprehensive model performance evaluation for the full year of 2002 is performed for the first time for CMAQ-MP using the surface networks and satellite measurements. CMAQ-MP shows a comparable and improved performance for most CAPs species as compared to an older version of CMAQ that did not treat HAPs and used older versions of national emission inventories. CMAQ-MP generally gives better performance for CAPs than for HAPs. Max 8-h ozone (O3) mixing ratios are well reproduced in the O3season. The seasonal-mean performance is fairly good for fine particulate matter (PM2.5), sulfate (SO42-), and mercury (Hg) wet deposition and worse for other CAPs and HAPs species. The reasons for the model biases may be attributed to uncertainties in emissions for some species (e.g., ammonia (NH3), elemental carbon (EC), primary organic aerosol (POA), HAPs), gas/aerosol chemistry treatments (e.g., secondary or- ganic aerosol formation, meteorology (e.g., overestimate in summer precipitation), measurements (e.g., NO3-), and the use of a coarse grid resolution. CMAQ cannot well reproduce spatial and seasonal variations of column variables except for nitrogen dioxide (NO2) and the ratio of column mass of HCHO/NO2. Possible reasons include inaccurate seasonal allocation or underestimation of emissions, inaccurate BCONs at higher altitudes, lack of model treatments such as mineral dust or plume-in-grid process, and limitations and errors in satellite data retrievals. The process analysis results show that in addition to transport, gas chemistry or aerosol/emissions play the most important roles for O3 or PM2.5, respectively. For most HAPs, emissions are important sources and cloud processes are a major sink. Simulated P H2 H O2/P HNO3 and HCHO/NO2 indicate VOC-limited chemistry in major urban areas throughout the year and in other non-urban areas in winter, but NOx-limited chemistry in most areas in summer.
The Coupling of Voltage and Frequecncy Response in Splitting Island and Its Effects on Load-shedding Relays  [PDF]
Hao Yang, Baohui Zhang
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54B128
Abstract:

The voltage and frequency dynamics interact with each other in the island after splitting. The current frequency response model without considering the voltage effect would bring remarkable errors when analyzing the frequency dynamic progress in the island with large-capacity active-power shortage. In this paper, coupling effects of voltage and frequency are studied to indicate that initial reactive-power deficit and load characteristics have strong effects on the coupling effects of the voltage and frequency. Moreover, control effects of currently used under frequency load-shedding relays (UFLS) and under voltage load-shedding relays (UVLS) which are installed and executed independently are examined to find that it would sometimes cause excessive or inadequate control without considering the coupling, suggesting that it is necessary to develop coordinate control methods for voltage and frequency problems.

The Expression of VEGF-C and It’s Receptor VEGFR-3 Correlates with Lymph Node Metastasis in Gastric Cancer  [PDF]
Chun Yang, Zhaoda Zhang
Open Journal of Gastroenterology (OJGas) , 2014, DOI: 10.4236/ojgas.2014.412050
Abstract: Background: Regional lymph node invasion and metastasis may happen early during the progres-sion of gastric cancer. The lymphadenectomy is still the key method to treat lymph nodemetastasis. In the recent years, scientists have found some growth factors and receptors that can promote angiogenesis which also play an important role in adjusting the formation of the new lymph vessel, and lymphangiogenesis may play a key role in the process of lymph node metastasis. Objectives: This study aims to explore the correlation between the expression of vascular endothelial growth factor-C (VEGF-C), vascular endothelial growth factor receptor 3 (VEGFR-3) and lymph node me-tastasis (LNM), and its impact on prognosis of patients with gastric cancer. Methods: The samples were collected from gastric cancer database of Sichuan Provincial People’s Hospital from 2005 to 2007, which were registered and followed up. The samples were divided into two groups according to situation whether there is lymph node metastasis, which is lymph node metastasis N(+) and without lymph node metastasis N(﹣). The expression of VEGF-C, VEGFR-3 and CD34 were measured by immuno histochemistry staining with monoclonal antibody (anti-VEGF-C, anti-VEGFR-3, and anti-CD34). Kaplan-meier, logistic and Cox regression was performed to explore their impact on the prognosis of patients with gastric cancer. Results: In total 186 cases were collected, 96 cases in N(+) group and 90 cases in N(﹣) group. The percentage of VEGF-C expression is 54.83% (102/186) in all groups, 73.9% (71/96) in N(+) group, and 34.44% (31/90) in N(﹣) group (p = 0.001). The percentage of VEGFR-3 expression is 33.33% (62/186) in all groups, 44.78% (43/96) in N(+) group, and 21.11% (19/90) in N(﹣) group (p = 0.001). There are no statistical differences in microvessel density (MVD) between N(﹣) and N(+) group. The average lymphatic vessel density (LVD) was significant different between N(+) and N(﹣) group (26.23 ± 8.2 and 18.46 ± 7.4, t = ﹣2.427, p = 0.016). The five-year overall survival rate of N(+) group is 31% and the N(﹣) group is 66%; there are statistical differences between the two groups (Log rank = 27.15, p = 0.001). The five-year overall survival rates of VEGF-C positive group and VEGF-C negative group are 36% and 59%, with the statistical differences (Log rank = 27.15, p = 0.001). And the five-year overall survival rates of VEGFR-3 positive group and VEGFR-3 negative group are 31% and 43%, also with the statistical differences (Log rank = 5.241, p = 0.041). Conclusions: The
Service Cooperation Incentive Mechanism in a Dual-Channel Supply Chain under Service Differentiation  [PDF]
Qiaoru Yang, Meng Zhang
American Journal of Industrial and Business Management (AJIBM) , 2015, DOI: 10.4236/ajibm.2015.54025
Abstract: The co-principal-anent models of manufacturer and retailer are built under the complete information and asymmetric information. In addition, the optimal profit sharing and the optimal fixed payment ratio are analyzed and compared in both situations. A motivate mechanism about service effort provided by the manufacturer towards the retailer in a dual-channel supply chain is studied. It implies that the profit of manufacturer under asymmetric information decreases dramatically contrasted to complete information and the retailer can gain profits by providing lower services, thus refusing deficiency of the supply chain.
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