3D finite elements analysis of vertically loaded composite piled raft

In recent years,a new type of foundation named composite piled raft foundation (also called long short composite piled raft) has been developed.Where designing shallow foundations would mean unacceptable settlement,or other environmental risks exist which could impair the structure in the future,composite piled raft foundations could be used.Finite element method was applied to study the behavior of this type of foundation subjected to vertical loading.In order to determine an optimal pile arrangement pattern which yields the minimum settlement,various pile arrangements under different vertical stress levels were investigated.Results show that with increasing the vertical stress on the raft,the effectiveness of the arrangements of short and long piles become more visible.In addition,a new factor named "composite piled raft efficiency" (CPRE) has been defined which determines the efficiency of long short piles arrangement in a composite piled raft foundation.This factor will increase when short piles take more axial stresses and long piles take less axial stresses.In addition,it is found that the changes in settlements for different long short piles arrangement are in a well agreement with changes in values of CPRE ratio.Thus,CPRE ratio can be used as a factor to determine the efficiency of piles arrangements in composite piled raft foundation from the view point of reducing raft settlements.

Influence of the Feed Gas Composition on the Fischer-Tropsch Synthesis in Commercial Operations

Key technical challenges relating to the Fischer-Tropsch （F-T） synthesis applied in the commercialization of coal/gas-to-liquids （CTL/GTL） technologies have been reviewed. Based on the experiences accumulated from pilot plant, semi-work test and lab researches, the influences of the H2/CO ratio and the CO2 in the feed gas on the F-T process as well as on CTL/GTL complex in terms of product yields, energy efficiency and carbon utilization efficiency have been studied. Being contrary to the current design schemes for F-T process using the coal derived syngas and the iron-based cata lyst, it is suggested to feed the F-T synthesis unit with a syngas having a H2/CO ratio of 0.5 and then adjusting to 1.4 via the recycling process. As a result, the carbon efficiency of the whole plant could be reached to as high as 50%. For the issue of CO2 addition to the feed gas, it is proved that only a diluting role is played under the current commercial slurry phase F-T process.

Distributed Algorithms for Event Reporting in Mobile-Sink WSNs for Internet of Things

Wireless Sensor Networks（WSNs） have many applications, such as climate monitoring systems, fire detection, smart homes, and smart cities. It is expected that WSNs will be integrated into the Internet of Things（IoT）and participate in various tasks. WSNs play an important role monitoring and reporting environment information and collecting surrounding context. In this paper we consider a WSN deployed for an application such as environment monitoring, and a mobile sink which acts as the gateway between the Internet and the WSN. Data gathering is a challenging problem in WSNs and in the IoT because the information has to be available quickly and effectively without delays and redundancies. In this paper we propose several distributed algorithms for composite event detection and reporting to a mobile sink. Once data is collected by the sink, it can be shared using the IoT infrastructure. We analyze the performance of our algorithms using WSNet simulator, which is specially designed for event-based WSNs. We measure various metrics such as average residual energy, percentage of composite events processed successfully at the sink, and the average number of hops to reach the sink.