Advanced Materials Research Vols. 374-377

Abstract: Excess sludge disintegration at normal temperature to promote hydrolysis and acidification is an effective method. The mechanisms, treatment effects and future prospects of commonly studied techniques, such as mechanical treatment, acid-base treatment, ultrasonication and ozonation were reviewed and analyzed. It is put forward that combination of different techniques is the most effective way to improve the efficiency of sludge treatment.

Abstract: Numerical modeling of open channel flows with dam-break using explicit finite difference schemes is constrained by the choice of time step, which is limited by the CFL stability criteria. To overcome this limitation, in this work we introduce the application of an algorithm to the field of computational hydraulics. By coupling this algorithm to a second-order accurate MacCormack scheme, we demonstrate that the solution can be accelerated to the desired transient state. The present formulation has been tested to simulate a dam-break flow. The close agreement between the obtained results and the theoretical findings indicates the reliability of the proposed algorithm.

Abstract: In this study, the poly(vinylidene fluoride) (PVDF) Flat ultrafiltration membrane was prepared the gel phase inversion method using different polymer(PEG,PMMA,PVA,PVP) as addition. The flux attenuation and resistance of membrane used for treating the secondary treated water of Urban sewage were studied by ultrafiltration (UF) experiments. The influence of addition to the morphology structure and anti-fouling performance of PVDF UF membrane was analyzed.Result show that using PVA and PVP as addition, the PVDF membranes had through macropore structure in cross-section and the appearance of larger macrovoids in the porous substructure,with the lower contact angle, high efficiency producing water percentage, good washing recovery rate. Meanwhile, adding PEG and PMMA in membrane,which was easy to form irreversible plugging hole pollution owing to distribute some teardrop deadend hole.

Abstract: The feasibility of saving energy for A2/O processes was studied in a wastewater treament plant located in beijing by means of field investigation and lab-scale experiment. The results indicate that there are two operable ways to save energy in A2/O processes. One is to control the DO strictly within 2～3 mg/L in aeration tank and to aviod over-aeration,the other is to shift the forepart of the aerated tank into anoxic tank,by which 17.1% of aration could be reduced and about 13.6% of TN removal rate could be increased.

Abstract: A numerical model for simulating of 2D flow around a spur dike was presented by using the physical fractional-step method. The water governing equations were separated into three parts. The first is a convective problem; the second is a diffusive problem; and the third is a source term. The advantage of this method is that in the convective-diffusion equation a more reasonable scheme for the convective and diffusive operator is adopted respectively. Numerical simulation for 2D flow around a spur dike was implemented. The comparisons with other numerical solutions show that the proposed method can be capable of dealing with 2D spur-dike flows.

Abstract: The paper presents a qualitative effect of ventilation mode at daytime, night ventilation flow and outdoor air temperature, the temperature differences between of indoor air setting and outdoor air on cooling load reduction and indoor air temperature fluctuation at nighttime using thermal mass and night ventilation. A simple residential building model is chosen to obtain the hourly variation of cooling load at daytime and indoor air temperature at nighttime. It is noted that the temperature distribution of thermal mass material governed by an one-dimensional non-steady heat conduction equation .is considered in the paper. The dependence of the cooling load and indoor air temperature at nighttime on night ventilation flow, the outdoor air temperature, the temperature differences between of indoor air setting and outdoor air is further validated. Our results show that only suitable night ventilation flow with suitable outdoor climates and the appropriate temperature differences between of indoor air setting and outdoor air will benefit most. The present work provides guidance for designing night ventilation.

Abstract: Dusts and condensation which exist in the application of solar light pipes can affect daylighting performance. The influence of daylighting performance of solar light pipes by dusts and condensation was studied in this paper. Through measuring daylighting performance of skylight dome on different condensation conditions, it was proved that as the drop’s mean diameter from small to big, the transmitting efficiency is directly proportional to the drop’s mean diameter, and then is inversely proportional to a certain value. Through measuring the overall daylighting performance of solar light pipes on three different conditions—clean, dusts and condensation on sunny and cloudy days, the illuminance flux was obtained. The experimental results indicated that dusts and condensation worsen the daylighting performance of solar light pipes, and dusts had bigger influences than condensation.

Abstract: Indoor air quality of commercial kitchen is investigated and analyzed through velocity, temperature, humidity, and CO2 concentration under different air change rate and supply air temperature. the best air change rate is 30 times per hour and air supply temperature is 301.15K for kitchen, the mean value of the minimum velocity and standard deviation is 0.410m/s and 0.129 respectively, the maximum of the average concentration of CO2 is 659.78ppm, which is less than the acceptance criteria (CO2<1000ppm), and the energy utilization coefficient is maximum of 1.352. Research results show that this air supply mode can optimize indoor air quality.

Abstract: The balcony type flat solar heating water system is becoming the first choice of high residential building for it’s high thermal efficiency, simple structure, safety,high building integration and so on. But the main load of this system is large and all on the south balcony, so we need structure analysis. This paper takes YIN CHEN balcony type flat solar as an example, choosing three buildings, respectively with 18, 24 and 34 storeys, applying PKPM--SATWE to analyze the structure. By comparing the results we find this system has minor effect on structure, reinforcement,structure foundation.

Abstract: With the rapid development of social economy, the noise pollution of road traffic increasingly serious. In 2010 the roads with quality road traffic noise account for 68%. This paper will study the measure to reduce the traffic noise from the urban master plan. Moreover the measures and recommendations will be proposed directly and indirectly, which includes road material, road supplementary facilities, residence number, city layout and others.