An Transaction Cost Analysis on Products’ Adaptability to E-Commerce

Based on theories of transaction cost economics, this paper study up on the relationship between product cognitive, transaction complexity and transaction cost, and examined the impact of product cognitive, transaction complexity on the product suitable for E-commerce. Being difference from the previous point of view that the product cognitive would reduce transaction cost, and transaction complexity would increase transaction cost, that combination with previous researches, we conclude that transaction cost tends to influence product suitable for E-commerce; and with the product cognitive increasing and transaction complexity reducing, transaction cost reduced so that the product are more suitable for E-commerce

Hit Ratio Driven Mobile Edge Caching Scheme for Video on Demand Services

More and more scholars focus on mobile edge computing (MEC) technology, because the strong storage and computing capabilities of MEC servers can reduce the long transmission delay, bandwidth waste, energy consumption, and privacy leaks in the data transmission process. In this paper, we study the cache placement problem to determine how to cache videos and which videos to be cached in a mobile edge computing system. First, we derive the video request probability by taking into account video popularity, user preference and the characteristic of video representations. Second, based on the acquired request probability, we formulate a cache placement problem with the objective to maximize the cache hit ratio subject to the storage capacity constraints. Finally, in order to solve the formulated problem, we transform it into a grouping knapsack problem and develop a dynamic programming algorithm to obtain the optimal caching strategy. Simulation results show that the proposed algorithm can greatly improve the cache hit ratio

Further Paleomagnetic Results from the Permian Emeishan Basalt in SW China

In recent years scientists at home and abroad have been conducting paleomagnetic investigations on the Permian Emeishan Basalt in SW China. The results reported, however, vary from one locality to another. We report here some new paleomagnetic results for the Emeishan Basalt from three localities in W. Sichuan and Yunnan provinces and compare them with relevant data published hitherto

Resisting flow-laboratory study of rheotaxis of the estuarine copepod Pseudodiaptomus annandalei

【英文文摘】Rheotaxis is a ubiquitous phenomenon among aquatic animals and thought to be an adaptation to maintain populations in flowing waters. While many estuarine copepods can retain their populations in estuaries with net seaward flow, rheotaxis of individual copepods has not been reported before. In this study, the behavior of a calanoid copepod Pseudodiaptomus annandalei in flow was examined in a recirculating laboratory flume. This estuarine copepod displayed different responses to ambient flow fields while swimming in the water column or attaching to the flume bed (walls). Copepods in the water column showed vigorous countercurrent swimming by occasional bounding when flow velocity was increased up to 2.1 cm s 1, but none of the individuals in the water column were retained in the flume when flow speeds were higher than 4 cms 1. This indicates P. annandalei profits little from rheotaxis to withstand flow when they were swimming in the water column. Instead, more individuals attempted sinking downwards to the slow flow region near the flume bed (walls) and showed active substrate attachment to avoid being flushed out by the high-velocity channel flow. The results suggest that P. annandalei benefits from rheotaxis and association with the substrate which allows them to hold position well at ambient flow velocities up to 3 cms 1. These adaptive responses might be important for population maintenance

Preliminary study of the retention mechanism of planktonic copepods in the Jiulong Estuary in China

【中文摘要】 The horizontal and vertical distribution patterns of five planktonic copepods,Calanus sinicus, Acartia pacifica, Tortanus derjugini, Acartiella sinensis and Pseudodiaptomus poplesia, predominant in the Jiulong Estuary, were investigated from May 2003 to April 2004. The results showed that the distribution of these copepods was related to the tidal period but that each species had its own specific pattern. C. sinicus showed no tidal vertical migration behavior and was thought to be a non-residen

Mechanism Study on the Axial Compressive Performance of Short Square CFST Columns with Different Stiffeners

In order to limit the disengaging of short square concrete-filled steel tube (CFST) columns and strengthen the combined action of steel tubes and concrete, a reinforcing method of stiffener is put forward in this paper. The axial compression performance and mechanism are studied through experiments, which indicate that (1) the buckling model of stiffening members changes into double wave, (2) stiffeners enforce the constraint in core concrete, (3) stiffeners can effectively improve the ultimate bearing capacity, (4) the stiffeners increase the stress in the middle of the steel tube and improve the distribution of stress for the core concrete, and (5) the direct ribs have more influence on the bearing capacity while ribs with holes have more impact on the deformation of the tube. At the end of the article, a formula for calculating the ultimate bearing capacity is presented, which can bring out a more accurate bearing capacity value

Analysis of Large-Strain Consolidation Behavior of Soil with High Water Content in Consideration of Self-Weight

Based on the axisymmetric large-strain consolidation (ALSC) model with the void ratio as the variable under equal strain condition, difference schemes of model’s equation, initial condition, and boundary condition were given. Taking phosphatic clay in Florida as a research object, the consolidation behaviors of soil with high water content by axisymmetric large-strain theory and one-dimensional large-strain theory were analyzed. The effect of different kinds of consolidation theories and self-weight stress on an average degree of consolidation was evaluated. The development of the void ratio and excess pore water pressure along the soil layer was clarified. The results show that the theoretical value of Terzaghi’s consolidation degree is always less than that of ALSC (Us, the average degree of consolidation defined by strain)-vertical drainage in the consolidation process. Terzaghi’s solution overestimates the dissipation rate of excess pore water pressure during the earlier consolidation period but underestimates it during the later consolidation period. The degree of consolidation calculated by Hansbo develops faster than ALSC (Up, the average degree of consolidation defined by stress)-radial drainage, but slower than ALSC (Us)-radial drainage. In the ALSC model, Us is always been faster than Up. The effect of self-weight on the consolidation degree of axisymmetric large-strain consolidation theory is relatively small (maximum error is less than 16%), while it can accelerate the consolidation rate of soil in one-dimensional large-strain consolidation theory largely. When only the vertical drainage occurs, the consolidation rate in the middle of the soil is obviously lagging the upper and lower parts, while the radial drainage can reduce the void ratio and the excess pore water pressure along the soil layer uniformly and more rapidly