Energy consumption analysis and reconstruction of subway platform screen doors in northern cities for energy saving

To analyze the influence of the platform screen doors (PSD) on energy consumption of subway environmental control systems in northern cities and to make good use of piston wind, EnergyPlus, an energy analysis and thermal load simulation program, is used to evaluate such systems in northern cities. A computational fluid dynamics (CFD) simulation is made to model the velocity and temperature field of a subway station and to predict the effect on PSD reconstruction using Airpak. Compared to a system with automatic platform gates, a PSD system has 2% lower energy consumption. Thus, PSDs are inefficient for saving energy in northern cities. Because electricity consumption by ventilation equipment increases notably when PSDs are used, particularly by under platform exhaust fans, little difference exists in the overall energy consumption with or without PSD. More thoroughly using piston wind in transition seasons and the winter is the key to solving the high energy consumption problem. The energy analysis and CFD simulation results show that the adjustable vents in PSD can use the piston process to introduce outside air, thereby reducing ventilation energy consumption notably. Because the vents can be closed, PSDs also can save energy in the summer. Using these recommendations can reduced annual energy consumption 30%.     

Anti sliding pile performance under acid stress coupling

Anti sliding piles are an important engineering structure used extensively in landslide prevention. Their durability influences their work lives. In a laboratory model experiment of a cantilevered anti sliding pile under acid stress coupling, the pile body displacement variation is monitored continuously, and both concrete strength and neutralization depth are tested. The results indicate that the concrete strength decreases gradually under acid stress coupling, while the displacement increases continuously. The neutralization depth of the concrete in the anti sliding pile is linear to the square of duration in acid stress coupling.     

Reproducing kernel particle method for numerical analysis of Mindlin plate bending on a Winkler foundation

The reproducing kernel particle method (RKPM) is a typical meshless method based on kernel function simulation. Based on the interpolating shape function of RKPM and Mindlin plate theory, the governing equations of RKPM to the deflection solution of Mindlin plate bending on a Winkler elastic soil foundation are established. Numerical results indicate that the above method and the corresponding program are effective and accurate.     

A new parameter for evaluating waveform distortion of partial discharge signals after de noising

The alternating detail parameter (ADP) is a new parameter to represent waveform micro distortion. It is proposed to overcome the shortcomings of the traditional evaluation parameters, the normalized correlation coefficient (NCC) and the variation trend parameter. This proposal is based on the principle that two discrete waveforms are more similar if the ratio of their corresponding differentials is close to one. ADP is shown to be correct by power spectrum analysis. Simulation research demonstrated that ADP is valid for evaluating the effect on the de noised partial discharge signal by associating NCC with signal noise ratio.     

The effect of Ce addition on As cast microstructures of AZ31 magnesium alloy

Various opinions still exist regarding the grain refinement of magnesium alloys resulting from Ce addition. We investigate effect of Ce addition on the as cast microstructures of AZ31 magnesium alloy. The research results indicate that adding from 0.5 wt% to 1.5 wt% Ce to AZ31 magnesium alloy does not effectively refine the alloy grains; instead, the opposite effect results, causing obvious grain coarsening. The coarsening trend is related to the amount of Ce. After adding 0.5 wt% Ce to AZ31 magnesium alloy, the average alloy grain size increases from 60 μm to 164 μm. Furthermore, increasing the amount of Ce added from 0.5 wt% to 1.5 wt% causes the average grain size to decrease gradually. The average grain size of AZ31 magnesium alloy with and additional 1.5 wt% Ce still exceeds that of the AZ31 magnesium alloy without additional Ce, however.     

Model and algorithm of transmission congestion management basedon matchmaking tradeoff competition mechanism settlement

A new congestion management model based on high low settlement is proposed for the electricity market. The model combines the transaction mechanism and congestion management to eliminate congestion in branches with the minimum equivalent increase in the system regulating fee. The equality constrains are the branch overloads, the generator sensitivities, and the corresponding adjustments, respectively. By introducing the Lagrange multiplier and a relaxation factor, the nonlinear programming problem with constraints can be translated into an unconstrained nonlinear programming problem. The regulating values of the generators thus can be obtained. The proposed algorithm is verified by a 6 bus system.     

Study on thermal performance of vessel type green roof

The thermal parameter measurements was carried out for vessel type green roof and bare roof in the air conditioned indoor environment in summer 2008 in Xiamen, China. The results show that temperature difference between internal surface of green roof and indoor air is about 1.5 ℃, and the heat flow from green roof is about 5.0 W/m the additional equivalent thermal resistance of vessel type green is larger than 1.0 m2·K/W.     

Deformation Monitoring and Its Control in a Shallow buried Large span Tunnel Constructed Using the Pile Beam Arch Method

Deformation monitoring and control measures of a shallow buried large span tunnel constructed using the pile beam arch (PBA) method are described, taking the North Gongti Road Station of Beijing Metro line 10 as an example. Based on the monitoring datum, the crown settlement, convergence, ground settlement of the tunnel and the bridge foundation settlement are analyzed. The results show that (1) the PBA tunneling method can restrain the ground settlement and deformation of a shallow buried large span tunnel; (2) the depth, tunnel span and pilot tunnel construction may influence the deformation of a shallow buried large section tunnel significantly; and, (3) advanced conduit grouting, timely preliminary support and permanent lining construction can reduce the deformation effectively.     

Deformation of Soft Ground with Consideration of the Concomitant Damage

On the basis of continuum damage mechanics theory, the effective stress theory of damaged porous media was presented and its modified self contained seepage differential equation was deduced. The traditional Drucker Prager yield criterion subsequently was modified, and a coupled seepage and damage finite element computer program compiled that was combined with the modified Biot consolidation equation. A simple roadbed foundation model then was analyzed and calculated using the computer program we compiled, and the typical node settlement, pore pressure, and damage variables were discussed and compared with those from the analytic solution. The results show that the damage finite element program we compiled is reasonable and effective.     

A Small Scaled Liquid Dehumidification Air Conditioning System

We studied the dynamic characteristics of dehumidification and regeneration of CaCl2 solution, based on building dehumidification load and economical operation and conducting an experiment on a small scaled liquid dehumidification air conditioning system. Experimental results show that three main factors affect the performance of CaCl2 solution: solution temperature, solution concentration, and inlet air humidity. The dehumidification capacity of the CaCl2 solution is 32 g/kg in experimental conditions. Its regenerating performance is approximately 1.3~9 times than that of dehumidifying. After summarizing, we consider the liquid desiccant dehumidification with CaCl2 solution has substantial potential to be improved and generalized.