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Now showing items 1 - 16 of 72

  • Trade credit contract in the presence of retailer investment opportunity

    Zha, Yong   Chen, Kehong   Yue, Xiaohang   Yu, Yugang   Mukhopadhyay, Samar  

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  • Estimating monthly average temperature by remote sensing in China

    Li, Long   Zha, Yong  

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  • Service supply chain coordination with platform effort-induced demand

    Zha, Yong   Zhang, Jiahong   Yue, Xiaohang   Hua, Zhongsheng  

    In this study we investigate the effort of a service platform in cooperation with a hotel and its influence on the hotel’s decision about the quantity of reserved rooms. We begin with a newsvendor hotel facing two kinds of customers: D-customers and C-customers. The D-customers order rooms from the hotel’s front desk while the C-customers book rooms through a service platform, i.e., Ctrip.com. The hotel makes decisions about how many rooms to allot to Ctrip.com to achieve optimal profit. Two newsvendor settings are proposed that depict the demands of the two parties independently. We discuss a fixed payment contract and a cost sharing contract and find that the cost sharing contract achieves channel coordination and that the division of profit depends upon the hotel’s payment to Ctrip.com. We then extend our study by taking into consideration the effort Ctrip.com exerts. We verify that a cost sharing contract can achieve channel coordination imperfectly if the idle cost of a vacant reserved room is shared between the hotel and Ctrip.com. Further, given that the cost of effort is shared, the channel is coordinated and a win–win is guaranteed as well if the terms of the new cost sharing contract are properly chosen.
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  • Efficiency improvement based upon overall value judgment and weight restriction

    Zha, Yong   Wang, Jun   Linlin, Zhao   Liang, Liang  

    Purpose – The purpose of this paper is to consider the following problem: the authors consider a new constructed unit system to indicate the characteristics of the inputs and outputs of different decision-making units (DMUs) and propose several modified models to calculate their efficiencies based on overall value judgment and weight restriction in the production process. Design/methodology/approach – This paper applies principal component analysis (PCA) to analyze the original value judgment information, and the key indices in the production process are extracted. The modified data envelopment analysis (DEA) models are proposed and DEA efficiencies and their projections are calculated. Findings – By incorporate PCA and DEA, the authors propose new virtual DMUs composed of unique optimal multipliers of each DMU. Crucial indexes are extracted and the weights of inputs and output are ranked through using PCA by taking the preference and value judgments of all DMUs into consideration. Weight constraints from the ranking are utilized to improve the traditional CCR-DEA model. The empirical results validate the feasibility of the approach. Practical implications – The method can be used in many organizations which have excessive amounts of inputs and outputs variables, such as banks, chain stores, car factory, etc. Originality/value – This paper presents an integrated methodology of using PCA and DEA for considering the preferences of the inputs and outputs and value judgment of all DMUs and ranks the importance of the indicators from the overall perspectives.
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  • The Prevention of Major Bile Duct Injures in Laparoscopic Cholecystectomy

    Zha, Yong   Chen, Xun-Ru   Luo, Ding   Jin, Yun  

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  • Simulation analysis of atmospheric SO2 contributions from different regions in China

    Jiang, Jie   Zha, Yong   Li, Long  

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  • Aerosol Indices Derived from MODIS Data for Indicating Aerosol-Induced Air Pollution

    He, Junliang   Zha, Yong   Zhang, Jiahua   Gao, Jay  

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  • A New Spectral Index for Estimating the Oriental Migratory Locust Density

    Zha, Yong   Ni, Shaoxiang   Gao, Jay   Liu, Zhenbo  

    It is very important to acquire timely information on the spatial distribution of locust populations in order to bring a locust outbreak under control quickly. In this study, we propose a new method for estimating the Oriental migratory locust density using a Locust Density Index (LDI). This index is based on the change in vegetation before an outbreak and shortly after the outbreak, taking into account the pre-outbreak vegetation conditions as well. This method was applied to study three locust-infested sites in Huanghua City, Hebei Province in China during a 2002 outbreak. NDVI images were derived from radiometrically corrected multi-temporal Landsat TM/ETM+ data recorded during and after the outbreak. After radiometry of the post-outbreak NDVI image was standardized to that of its during-outbreak counterpart, their difference multiplied by the pre-outbreak NDVI (termed LDI) was used to map the density of locusts at five levels of no locust, low, moderate, high, and very high. Nearly 90 percent of the study sites had a low to moderate locust density. Results produced with the proposed LDI method are similar to those observed on the ground with an accuracy of 88.9 percent. This proposed LDI method is easy to implement. It allows quick and accurate mapping of locust density from satellite data.
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  • Utility-based two-stage models with fairness concern

    Zha, Yong   Wang, Jun   Liang, Nannan   Zhou, Chuiri  

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  • Quantitative detection of change in grass cover from multi-temporal TM satellite data

    Zha, Yong   Gao, Jay  

    In this paper, change in grassland cover near Lake Qinghai, west China was quantitatively detected from satellite remote-sensing data. Two Thematic Mapper images recorded in 1987 and 2000 were radiometrically corrected and used to derive the Normalized Difference Vegetation Index (NDVI). The NDVI image in 2000, after standardization via in situ measured spectra, was converted to a map of grass cover with the aid of in situ grass-cover samples. Another map was produced from the 1987 image after it was radiometrically benchmarked to the 2000 image using the calibration to like-values method. Comparison of these two maps revealed that a total of 36.28 km 2 of grassland had a higher cover, versus 44.72 km 2 that experienced grassland degradation in the study area. The absolute cover changed by a net value of -1.27%. The magnitude of change is related inversely to the value of the cover. The large majority of the area (82.6%), however, had a small change that was within plusmn20%. With this proposed method, it is possible to quantify changes in grassland cover from multi-temporal satellite data if one set of ground samples are concurrently collected with one of the satellite images.
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  • Dynamic pricing in the presence of reference price effect and consumer strategic behaviour

    Chen, Kehong   Zha, Yong   Alwan, Layth C.   Zhang, Lu  

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  • Gallbladder-preserving Cholelithotomy in Laparoscopic and Flexible Choledochoscopic Era

    Zha, Yong   Zhou, Zheng-Zhong   Chen, Xun-Ru   Gan, Ping   Tan, Jing  

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  • Normalized difference haze index: a new spectral index for monitoring urban air pollution

    Zha, Yong   Gao, Jay   Jiang, Jianjun   Lu, Heng   Huang, Jiazhu  

    Haze is an undesirable meteorological and environmental phenomenon that can cause enormous harm to the environment, people's lives and health, and economic activities. This study focuses on Nanjing, Yangzhou and Suzhou in the lower reaches of the Yangtze River valley, China, which have suffered from the adverse effects of hazy weather in recent years. The spectral influence of haze on surface features was determined through analysis of the spectral variations of surface covers between hazy and haze-free days. On the basis of the established relationship, a new index called the normalized difference haze index (NDHI) was derived using moderate resolution imaging spectroradiometer (MODIS) data from winter 2008-2009. Correlation analysis of the derived NDHI with in situ observed PM 10 (particulate matter with diameter <10 mum) data reveals that NDHI over water bodies has a coefficient of 0.74, 0.57 and 0.67 with PM 10 for Nanjing, Yangzhou and Suzhou, respectively. It is concluded that NDHI is a reliable indicator of air pollution. It can be used as a new method of effectively monitoring air pollution from remotely sensed data.
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  • Optimal pricing and availability strategy of a bike-sharing firm with time-sensitive customers

    Chen, Yujing   Wang, Dong   Chen, Kehong   Zha, Yong   Bi, Gongbing  

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  • Research on Theory and Application of Multidisciplinary Design Optimization of Flight Vehicles

    Chen, Xiaoqian   Yan, Li   Luo, Wencai   Xu, Ling   Zha, Yong   Wang, Zhenguo   Multidisciplinary Aerospace Design Optimization Research Center, College ofAerospace and Material Engineering, National University of Defense Technology, Changsha, China, 410073  

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  • Characteristics of desertification and its rehabilitation in China

    Zha, Yong   Gao, Jay  

    The definition of desertification and its causes in the Chinese literature are reviewed and compared with those in international publications. Both Chinese researchers and their western counterparts have difficulty in reaching a generally accepted definition for desertification and an agreement upon the exact role played by human activities and environmental settings in desertification initiation and development. Tremendous efforts in China have gone into rehabilitating desertified land into productive uses with great contribution to existing knowledge in reclaiming desertified land. The early biological-oriented measures based solely on economic return have recently been replaced by a much more successful, multi-disciplinary approach of rehabilitation combined with preventive measures that follow sound ecological principles.
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