Applied Mechanics and Materials Vols. 295-298

Abstract: The research assesses the water quality to tourism development, shows the complex and dynamic relationships between humans and the natural environment. In total, 55 sets of data were detected in 11 samples, with the index of negative oxygen ion, oxygen ion, dissolved oxygen, PH, salinity, turbidity, electrolytic rate, total nitrogen, total phosphorus. The results show Water is weak acid and salinity, turbidity is low, with low degree of contaminated, total nitrogen content in 1.13 ug/mL the following, the total phosphorus content in 0.14 ug/mL the following. In the air over sampling points negative oxygen ion are more than 1000 per cubic centimeter, belongs to the pure and fresh air. Water quality of Zharu valley is much better than other valleys, The difference between samples quality is obvious in the other three valleys. According to the assumptions, human activities didn’t affect surrounding water quality apparently.

Abstract: The traditional valve control hydraulic systems have serious challenges in the harsh environment underground. The mathematical model of this new form of "motor - quantitative pump" controll system was established and simulated by using AMESIM software in this paper. According to the results of comparative analysis of the orifice parameters and the way to input signal, related parameters was determined, which can meet the characteristics of the system.

Abstract: Mid-stage Pulping Wastewater was pretreated in a combined system of microelectrolysis and Fenton oxidation-coagulation . When the aeration was 6L/min, the ratio of iron-carbon mass was 4/1, the addition of iron was 1500mg/L, pH was 4, and reaction time was 30min, the removal rates of COD and chrominance reached 65% and 60% respectively and the concentration of generated Fe²⁺ reached 157mg/L. Fe²⁺ generated by micro-electrolysis process was used for the following Fenton oxidation. When the conditions was without additional Fe²⁺, the addition of H₂O₂ (concentration is 30%) was 3mL/L, pH was 4, and the reaction time was 15min, the removal rates of COD and chrominance both reached over 80% and the concentration of generated Fe²⁺ reached 217mg/L. Fe³⁺ generated by Fenton oxidation was used for following studies of flocculation. The treatment efficiency of three kinds of flocculants PAM, PAC and silicate was compared. The results showed that the effect of PAM was best, the treatment efficiency reached the best when its additon was 0.15mL/L as pH was 7. the removal efficiency of COD reached 41% and the chrominance removal efficiency reached 75%, the final effluent chrominance was 4 and the COD concentration was 45mg/L which was lower than 60mg/L, that met with the first order of effluent standard.

Abstract: This work presents an experimental study to detecting the faults of engine using its noise. The noises produced by the engine and its accessory systems are numerous: whines, squeals, knock, rattles, and many other sounds. Faults diagnosis for Mitsubishis car engine model 2006 has been conducted and this diagnosis includes normal operating conditions for the engine (without malfunction) and for malfunctions situations at variable engine speed 1000,2000, 3000 and 4000 rpm respectively The engine data is acquired from a four cylinder one- petrol engine test bed under consideration at different operating states, and then simulated. Most of the conventional fault diagnosis techniques using sound emission and vibration signals are based on analyzing the signal amplitude in the time or frequency domain. For engine under fired and misfires spark the all the domain parameters (RMS amplitude, peak amplitude and energy) was processed using MATLAB software.It was found that fault detection and diagnosis for internal combustion engines is complicated by the presence of engine noise during normal operation. The average of amplitude found to be 450 x10-3m for normal engine working without any malfunction and 458x10-3m for misfire of one spark plug and for misfire of two spark plugs 457.8 x10-3m. In this study, some of the engine malfunction such as failure spark plug has been recorded, but we can generalize it to include all engine breakdown. Generally, sound emission signal serves as a promising alternative to the condition monitoring and fault diagnosis in rotating machinery when the vibration signal is not available. This research paper explores that automobiles could be major sources of noise pollution. Condition monitoring and fault diagnosis of IC engine through acoustic signal analysis is an established technique for detecting early stages of component degradation.

Abstract: The effect of incoherency of seismic waves and wave travel on the displacement and force response of jacket structure are investigated from the maximum force, reaction force, the displacement, and so on. The conclusions illustrate it is necessary to consider the effect of multiple support excitation. The research of the differences of seismic response under multiple support excitation from uniform excitation presents the theoretical foundation on aseismatic projects for long span space structures such as jacket.

Abstract: The purpose of this paper is to present a tradeoff study of airframe noise and field length due to wing area and flap setting configuration during conceptual design. The aircraft takeoff and landing length is predicted by the Matlab synthesis code for airliner conceptual design. The NASA’s Aircraft Noise Prediction Program (ANOPP) is used to evaluate the airframe noise signature. It is found that: (1) with the increase in wing area both the landing and takeoff field length will be reduced, and approach noise decreases whereas the takeoff noise increases; (2) with the increase in flap setting from 50 to 200, both landing and takeoff field length reduces but the noise level increases during takeoff and decreases during the approach. The results can help designers to select suitable values of wing area and flap setting to meet both the requirements of field length and noise levels.

Abstract: Through in situ tests on the impact vibration of a typical muck ground treatment major project directed by the first author, the vibration propagation law under the impact load for the ultra soft soil ground is obtained, and quantitative environmental safe control distance on the vibration influence is also gained. The main results are the two aspects. (1) The attenuation law of both level and vertical peak vibration acceleration with the horizontal distance can be described well by the negative power function; and the ground vibrations caused by tamping impact can be distinguished between two types, i.e. near-field and far-field. Near-field tamping vibration influence is confined to a small range of the tamping center, which decays obviously faster than the one of far-field. (2) The radius of influence of tamping vibration depends not only on the tamping energy but also the soil type. Loose, slightly dense soft soil has a larger energy absorption capacity and a smaller effect radius of tamping vibration than the dense and hard soil; and the vibration safe control distance is determined as 27.3m in the tests according to the safe boundary determined code of industrial and civil architecture in China.

Abstract: Mine ventilation system is serious pollution to the surrounding environment. Due to the air flow rate, high speed, strong noise radiation. In addition to the scientific and reasonable design for muffler, ventilation resistance loss calculation is one of the key successful factors of project design, in order to eliminate the noise pollution of mine ventilation system.In recent years,people's awareness level of the harm of noise rises ceaselessly, the environmental protection departments also gradually enlarges the management and punishment to noise pollution.The noise control of coal mine ventilation system with strong radiation and harm has become a pressing matter of the moment. Because the theory calculation of noise control design is fuzzy, Some environmental protection company implement noise control by virtue of experience or imitation of other engineering, leading to a series of problems, such as noise control can not reach the design standard, large ventilation resistance, energy consumption increased, regeneration noise exceed the standard, system vibration. Based on the systematic study for engineering design, i summed up the theory calculation rule for the coal mine ventilation system noise control, as reference to technical personnel.

Abstract: In order to analyze the role of air damping in synthesized damping of litchi tree vibration, the fruit tree was simplified into a cantilever firstly. Then, according to equations of equivalent stiffness, equivalent damping, and equivalent mass, the damping ratio of air resistance was analyzed. The results showed that such damping ratio increases with the height of canopy center and the canopy size, and decreases with canopy mass and trunk radius. Within normal trunk radius, trunk length, canopy size, and canopy mass range, the damping ratio of air resistance is much smaller than 1.

Abstract: In order to improve recoil mechanism’s buffering function of automatic weapon, using Newton’s second law, its recoil movement is analyzed and design model of magneto-rheological (MR) damper under impact loads is built. Structure parameter and control strategy are defined. Dampers’ characteristic curves at different magnetizing currents and different recoil speeds are tested on a damper indicator test bench. Some weapon’s recoil forces are artificially computed. The research results indicate that MR dampers have a perfect damping plateau effect. Recoil force of automatic weapon will be reduced by a big margin using the property that MR fluid can change at applied magnetic to control damping rules.