Applied Mechanics and Materials Vols. 121-126

Abstract: Aimed to enhance the efficiency of heart sound signal energy detection, a kind of heart sound signal energy detection system based on LabVIEW 8.5 is developed in this paper. The system makes use of saddlebag of signal processing and analysis tool of LabVIEW to detect and analyze energy of the heart sound signal. The system can detect, display, record and analyze the energy of heart sound signal. From the results of experiments, the detection and analysis of heart sound signal energy have importance clinical value to the earlier period diagnosis of coronary artery disease (CAD).

Abstract: Based on the vehicle dynamic equation in starting engine in-motion process for HEV, theoretical derivation is conducted to obtain the impact hardness equation in the process. By using matlab/simulink, the law of influence the parameters have on the impact hardness equation is analyzed. Then, coordinated control stategy between the clutch pressure and motor torque, and between motor torque and engine torque is proposed based on the influence law. At last a test bed of the starting engine in-motion for HEV is implemented. The test results show that the change rate of clutch pressure, motor torque and engine torque, can effectively coordinate the change relation between the clutch pressure, the motor torque, and the engine torque. And the test results satisfy the requirements of ride comfort in starting engine in-motion process for HEV well.

Abstract: Aiming at the limitation of the roadway-type barrier explosion device which is being used in the coal mine, this paper suggests to establish the gas recoil type barrier explosion device. Using the mechanism of the gas recoil type, it made the structure design of the solid barrier explosion device of the circle-arch roadway. The device has the better effect on the elimination of the damage and the influence of the high-temperature flame of the gas and coal dust explosion and the overpressure damage of the shock wave. Especially, it can have a more realistic function for the secondary explosion or multiple explosions of the underground gas explosion.

Abstract: Stress corrosion cracking behavior of the six heterogenic welding joints was investigated under the 1300ppm; 2300ppm and saturated H2S concentration by slow strain rate tests and influencing factors of different H2S concentration and welding material are analyzed to the stress corrosion cracking. It is showed that stress corrosion cracking is more sensitive above 1300ppm H2S concentration. With the H2S concentration increase, the maximal stress, elongation and the time of rapture decrease on heterogenic welding joints 1Cr9Mo/45 and 0Cr18Ni9/1Cr9Mo. But they are not influenced to the joint 0Cr18Ni9/45. It is also concluded that replacement of A302 by Inconel182 can improve the corrosion resistance of 1Cr9Mo/45 but can not make any influence on the joints 0Cr18Ni9/45 and 0Cr18Ni9/1Cr9Mo

Abstract: Since the expansion of the cement during curing was constraint by the steel tube, the concrete core in the self-stressing concrete-filled steel tubes (SSCFST) is under tri-axially compression before applying load, which increases the axial capacity of the SSCFST. In addition, Carbon fiber reinforced polymer (CFRP) wrapping can avoid bucking of the steel tube, increase the axial capacity and improve the durability of SSCFST. This study presents a theoretical study on axial capacity of the SSCFST wrapped with CFRP sheets. Several basic assumptions are proposed. The ultimate equilibrium method was employed to analyze the axial capacity, of which two limit states, including steel tube bucking and CFRP sheets rupturing were considered. The analytical results from an example show that the initial self-stress improves axial capacity of the SSCFST by about 30% and the CFRP reinforcement improves axial capacity by about 15%.

Abstract: Urban traffic system in Jinan is an vital important sphere to show the city image，as well as a carrier for the local culture. With the development of various lifestyles, it is not merely ornamental, but a cultural experience. At the same time, when the local culture functionality is combined with functionality and times, in order to get a better understanding of it ,modern technology and materials is indispensable to the explore. In this way, citizens will be granted with a better aesthesis.

Abstract: With the era of high oil prices and prominent contradict between domestic oil and gas supply and demand, a boom of unconventional natural gas development has set off. While a major success of shale gas development has been made in the United States, it has also brought a successful experience and advanced technology to China. China also have carried out deep research and have achieved certain results in coal bed methane and tight sandstone gas, etc. However, difficulties and problems faced in the development process need to be carefully dealt with .

Abstract: The application of urea peroxide in ramie oxidation degumming was discussed in this paper. And urea peroxide impact on the effect of ramie degumming was analyzed. The experimental results show that four parameters such as time, temperature, the amount of urea peroxide and the dosage of sodium hydroxide have influence on the fiber strength. At the same time, fiber strength with the increase of the amount of urea peroxide is reduced. The fiber strength and the dosage of urea peroxide basically appear linear characteristics. With the increase of time and the amount of sodium hydroxide, the single fiber strength of ramie increases firstly and then decreases. When the temperature is 95°C and the time is 3 hours, the fiber strength is the highest.

Abstract: SiO2 coatings were deposited on silver foils substrate by sol–gel method and their atomic oxygen (AO) erosion resistance was tested in a ground-based AO simulator. The surface morphologies and structures of the SiO2 coatings were investigated by Scanning Electron Microscopy (SEM) 、X-Ray Photoelectron Spectroscopy (XPS). The experimental results clearly demonstrate that this kind of coatings provided a good protection from AO attack. The erosion yield of the coatings was 2×10-26 cm3/atom, decreased by 30 times compared with that of the uncoated silver foils. This SiO2 layer significantly retarded the penetration of oxygen atoms, preventing further oxidation of the bulk silver. It was found that after AO exposure, the film structure tends to transfer from SiOH to amorphous SiO2. This implies that a more stable amorphous SiO2 structure could be formed in sol-gel SiO2 film during AO exposure. The results demonstrate that the coatings prepared by sol-gel technique can protect the silver from atomic oxygen erosion and can be used easily for practical application.

Abstract: Dynamic kill drilling is a technology which is applied in order to control the deep water drilling shallow gas or shallow wells flowing by establish a normal cycle automatically in the deepwater shallow wells section. Equivalent circulating density (ECD) is an important parameters to control the bottom hole pressure, in the ECD estimate, if we don’t consider the effects of low temperature on rheological parameters of drilling fluid, it will result in errors in ECD estimates. Considering the impact of low temperature on the rheological parameters, this paper determines the temperature, rheological parameters and the annulus circulating pressure loss of each well section. Then Superposing each well section annular circulating pressure loss together, and finally calculate the equivalent circulating density. The deeper the water the greater of difference between ECD prediction model and the results calculated by rheological parameters on ground, and the more shallow wells the larger of difference. Therefore, in the process of deep water surface layer dynamic killing, We need to predict the equivalent circulating density of drilling fluids (ECD) accurately.