道路雨水口布设方案对泄流能力影响的模拟研究

雨水口作为城市排水系统的重要组成部分,其布设情况对周边小区及道路积水的消除至关重要。为此,利用耦合了水文和水动力过程的数值模型,研究雨水口在不同道路纵坡坡度、布设数量和径流流量条件下的泄流能力。结果表明,道路纵坡坡度越大,雨水口的泄流能力越差,在小流量、雨水口数量为5个(间距为20 m)的条件下,当道路纵坡坡度从0.3%增至8%时,雨水口泄水率从55.64%降至21.05%;雨水口数量越多,其泄流能力越强,在小流量、道路纵坡坡度为0.3%的条件下,当雨水口数量从2个增至5个(间距由50 m降至20 m)时,雨水口泄水率由25.60%增至55.64%;径流流量越大,雨水口的泄流能力越差,在道路纵坡坡度为0.3%且布设5个雨水口的条件下,小、中、大3种流量下雨水口泄水率分别为55.64%、46.92%、37.28%。

Temperature Distribution in Ethylene Pyrolyzer

A good understanding of the detailed temperature distribution in the furnace plays an important role in the implementation of operation optimization and design improvement of ethylene pyrolyzer. Numerical simulation of the turbulent flow, combustion and heat transfer was carried out to investigate the temperature distribution in industrial furnace. Inhomogeneities of the flue-gas temperature distribution were observed in X, Y, and Z direction of the furnace from the simulated results. Along the height of the furnace, the average flue-gas temperature increased initially and decreased afterward, and reached its peak at the height of 5 m. The reactor tube skin temperature varied not only along the height of the furnace, but also around the circumference of the tube. The heat flux profiles from the furnace towards the reactor tubes followed the shape of the average flue-gas temperature profile. The heat flux of the inlet tubes was constantly higher than that of the outlet tubes at the same height in the furnace.

Short-Term Financing of Economic Order Quantity （EOQ） Inventory Model With Probabilistic Quality

In this paper, the classical economic order quantity （EOQ） inventory model assumption that all items of a certain product received from a supplier are of perfect quality is relaxed. Another basic assumption that the payment for the items is made at the beginning of the inventory cycle when they are received is also eased. We consider an inventory situation where items received from the supplier are of two types of quality, perfect and imperfect, and a short deferral in payment is allowed. The split between perfect and imperfect quality items is assumed to follow a known probability distribution. Both qualities of items have continuous demands, and items of imperfect quality are sold at a discount. A mathematical model is developed using the net present value of all cash flows involved in the inventory cycle. A numerical method for obtaining the optimal order quantity is presented, and the impact of the short-term financing is analyzed. An example is presented to validate the equations and illustrate the results.

Impact of Mobile Access to the Internet on Sales Completion Time in E-Commerce

Supported by a new generation of mobile devices, e-commerce is now in the process of being converted into m-commerce. While the traditional fixed PC access to the Internet continues to be important, the mobile access appears to attract more people because of its flexibility. The purpose of this paper is to develop and analyze a mathematical model for capturing how e-commerce performance would be affected by the mobile access to the Internet, where the original paper by Sumita and Yoshii （2010） is extended for better reality. The traditional e-commerce via the fixed PC access is compared with m-commerce which accommodates both the fixed PC access and the mobile access. The distribution of the number of products purchased by time t and the distribution of the time required for selling K products are derived explicitly. Numerical examples are given for illustrating behavioral differences between m-commerce consumers and traditional e-commerce consumers.

Weight distribution of Preparata codes over Z_4 and the construction of 3-designs

In this paper,we calculate the number of the codewords(with Hamming weight 7)of each type in the Preparata codes over Z4,then give the parameter sets of 3-designs constructed from the supports of the codewords of each type.Moreover,we prove that the first two families of 3-designs are simple and the third family of the 3-designs has repeated blocks.