Applied Mechanics and Materials Vols. 90-93

Abstract: There are different numerical models performed on hydrodynamic behavior of dam break flood in canals and floodplains based on 1D and 2D modeling approaches. In recognition of increasing demand to precise modeling of dam break flood, and due to the limited instructions to choose the best computational model, this article appraises the difference between 1D and 2D modeling of the phenomenon based on the logical comparison of the results. For this purpose the Zayandeh-Rood dam in Iran was used as the case study and MIKE11 and MIKE21 are used for numerical exploration of the problem. The reliability of each approach is assessed and the applicability of each method for exact analyzing the dam break phenomena was demonstrated.

Abstract: Abrupt changes of the channel bed elevation in hydraulic systems, e.g. in chutes, drops and steeped spillways, results to create a sever flow kinematic energy. This excess energy, can tend to different phenomena, such as tremendous forces, scouring and degrading the channel bed, resulting to destruction of the downstream hydraulic structures. The most important source to cause this phenomena is the the existence of sequent vertical drops along the the channel. In this study, the energy dissipation efficiency was increased by installing a new type of dissipaters namely netting dissipater on the crest of the vertical drops based on model experimtation. Also, the features of hydraulic jump, created in the stilling basin, were compared to those of a simple vertical drop. By assembling the above mentioned structure to the top of the stilling basin, the jet flow direction is changed, the degree of turbulence is increased and as the results, the kinematic energy loss increases and the length of the hydraulic jump decreses. The enhanced efficiency of the proposed structure was quantified based on the achieved experimental data.

Abstract: The national coordinates system used in Nigeria is the Universal Transverse Mercator projection, while China adopts the Gauss Krugger Transverse Mercator projection (GKTM). This paper studied the difference between UTM and Gauss(TM) projections and the regulation of projection deformation, and put forward the model of the coordinates system for the Nigeria railway, which shall be of great benefit in the survey, design, construction and referencing of the Nigeria railway project.

Abstract: The hydration ZrOH was loaded in the powdered activated carbon（PAC）,the aim to modify activated carbon, then the mixed liquor including poval(PVA) and sodium alginate tech grade (SV) , as the embedding agent ,embedded the modified PAC.The main investigation were that the hydration ZrOH concentration,the ratio of embedding agent composition and Curing liquid ingredient etc. influence the phosphorus removal . The orthogonal experiment determined the optimum prepared conditions of embedding adsorbent. The experimental results showed that : the optimum loaded conditions were that PAC average particle size was 0.5-1.0mm, hydration ZrOH concentration was 0.04mol/L;the optimum embedded preparation conditions were PVA mass concentration for 8%，SV mass concentration for 1.2%; the optimum cured conditions were the curing liquid ingredient was saturated boric acid with 2% CaCl2. The adsorption of phosphorus removal efficiency was 99.27%.

Abstract: To investigate the domestic sewage treatment processes fitting for small mountain towns in Three Gorges Reservoir Region, a demonstration project was built to treat domestic sewage which combined with anaerobic hydrolysis, natural water-dropping aeration and improved artificial soil rapid infiltration and was based on the features of large terrain elevation and many barren ravines. Changes of major pollutants were analyzed in the combined process. The impact of temperature and influent loadings on removal rates of pollutants was investigated. The results showed that, the treatment system had a strong resistance to the influent loadings with good removal rates of pollutants. There was a relationship between temperature and the removal rates of chemical oxygen demand, ammonia and total nitrogen in the system, where the removal rate of total phosphorus was not associated with temperature. There was a clear linear relationship between effluent concentration and influent loadings, effluent concentration increased with influent loadings. There were approximate logarithmic relationships between removal loadings per unit area and influent loadings.

Abstract: The simplified of fluctuating wind field and the basic theory of Spectral Proper Transformation（SPT）were expatiated. SPT was used to simulate the random wind field on long-span cable-stayed bridge, then the random wind field of the bridge was simulated by MATLAB program, an actual example was used to validate the validity and correctness of the MATLAB program. The results showed that SPT had the advantage of explicit physical meaning, high computational efficiency. It is an effective method to simulate the random wind field.

Abstract: Under the effect of water pressure in karst cave before tunnel face, water inrush happens when excavation face enters into the minimal value of safe thickness. Aiming at comparatively intact rock ahead of karst tunnel face, rock wall often appears to be tensile fracture. With some hypotheses, a mechanical model of water inrush for tunnel face instability has been established, furthermore, the analytical expression to calculate safe thickness of rock wall has been given based on the criteria of tension strength through elastical theories. Combined with Maluqing tunnel in Yiwan line, applicability and reliability of formula is discussed.

Abstract: Healthy indoor air environment quality is needed for healthy building hospital. Mycobacterium tuberculosis (MTB) is a microbial infectious agent which causes tuberculosis (TB) disease in human. Hence, health care workers (HCWs) are belonged to a highly potential risk group to be infected by MTB. This research aims to investigate the source and factor(s) of TB transmission in sustainable indoor air environment at the Hospital Sultanah Aminah Johor Bahru (HSAJB), Malaysia. The view taken in this paper is that the transmission dynamic of MTB from an active pulmonary TB (PTB) patient to another person via indoor air environment in the health care setting is generated as a result of an interaction between architect, building planner and owner, design and facility engineer, construction engineer, occupational health and safety professionals, hospital and HCWs, epidemiologist and public health officer. The findings were obtained by combining questionnaire and interview approaches using five ordinal measures of agreement using Likert Scale measurement. Analysis of qualitative data found that the source of MTB transmission was coming from active PTB patients especially those with sputum smear positive (SS+). The studied ambient parameters and factors affecting indoor air environment sustainability were thermal comfort, humidity, air pressure, temperature, duration exposure, area and volume, direction of air flow, lighting, air circulation exchange and MTB density in the air.

Abstract: For the problem of wetting collapsible loess foundation in loess area, and common methods used in dealing with collapsible loess foundation are insufficiency, new treatment technologies, including loess solidified by polymer and comprehensive method of dynamic compaction and chemical solidification, were proposed. Experimental studies on loess solidified by a series of SH were carried out. The results show that the loess solidified by SH has advantages of high strength, good water-resistance, and frost resisting, low-cost. Consequently, SH is feasible to deal with loess foundation. Because it fits in with the development trend for new combined technology in reinforcement of rock and soil, dynamic compaction and chemical solidification has some applying prospects. In order to establish this new method, things correlated with the study should be done.

Abstract: In this paper secondary lining of an underwater tunnel which had appeared I-longitudinal crack was taken as study object according to theory of fracture mechanics. Finite Element analysis was carried out to calculate the stress intensity factor at the tip of I-longitudinal crack which located in vault, then to analyze the extended state of crack based on double-K fracture criteria. The computation results indicate that the stress intensity factor at the tip of I-longitudinal cracks which appear within 20 degrees of the vault do not exceed unstable fracture toughness, lining is in stable growth stage and do not occur instable failure. The stress intensity factor at the tip of I-longitudinal cracks appeared in vault is maximum and appeared in both side of vault is minor, the further away from vault the less of stress intensity factor. When water level below the top of tunnel, with the rise of water level the stress intensity factor at the tip of I-longitudinal decrease and the external water pressure has restrain effect to the crack extension. When water level exceed the top of tunnel, with the rise of water level the stress intensity factor at the tip of large depth of crack decrease rapidly until arrive negative value, then increase backward until greater than unstable fracture toughness and cause lining structural local instable failure.