Dynamic response analysis of the submarine suspended pipeline impacted by dropped objects based on LS-DYNA

Based on ANSYS/LS-DYNA, the dynamics analysis software, and using nonlinear dynamic finite element method, the process of a submarine pipeline impacted by dropped objects is simulated, Some conclusions are drawn： First, the damage depth of suspended pipe is smaller than that of the bare pipe in case of the same fall energy, and with the increase of fall energy, the difference grows; Second, with the falling object＇s speed and mass rising, the deformation of pipeline intensifies at the impact site and the maximum vibration amplitude of submarine pipeline increases; Third, when the fall energy is equal, the smaller the contact area of falling objects and pipeline is, the greater the damage depth of pipeline becomes; Fourth, changes of seabed soil parameters （shear elastic modulus, internal friction angle, density） have less influence on the suspended pipeline＇s dent depths and maximum vibration amplitude,

Micro-process model of hydraulic shock absorber with abnormal structural noise

In order to discover the causes of the abnormal noise of shock absorbers, it is necessary to identify the operating characteristics of the shock absorbers. A micro-process model for operation of the hydraulic shock absorber was presented. A novel concept, which describes the process of hydraulic shock absorber by dividing it into smaller steps, was proposed. The dynamic model and the differential equations were established. The results of numerical simulation agree well with data obtained from the vibrostand test, indicating that the collision between the piston and the oil, the alternation of static friction and sliding friction acted between the piston and the cylinder, and the adherence between valve plate and piston result in impact on the piston head near the top dead center and the bottom dead center. Ultimately, the impact excites the high-frequency vibration of the piston structure, which can generate the abnormal noise in the hydraulic shock absorber after its transfer. And the maximum vibration acceleration on the piston head and the abnormal noise increase with the increase of the gap between the oil and piston rod head, the maximum static friction force and the adhering function, respectively.

Rigid-Plastic Dynamic Response of Reinforced Concrete Bridge Pier Impacted by Automobile

Bridge piers are impacted by autos sometimes. The pier usually has not been destroyed after once impact by auto. But there are few research on damage which will affect pier's capability, and most relative studies have focused the problems on piers impacted by vessels. The methods involve mainly sutra experience theory, numerical analysis, and experimental method. Owing to the complicacy of the bridge pier impacted by a vessel, there are few research derived with the sutra mechanics model and the piers impacted by autos. The dynamic response is studied here under the assumption of the rigid-plastic small-deformation for the pier impacted by auto. According to the Parkes beam model, the rigid-plastic theoretical solution is deduced. The final deformation is calculated by a practical example for the pier impacted by auto.

Dynamic Behavior of a New Hydraulic Steel Gate

A new style of hydraulic steel gate based on the principle of bionics is proposed in this paper. It has a fish-like shape and consists of right arches, invert arches, connection components and a face plate. It would be first applied in the project of Caoe River Sluice, used as both tidal barrage and flood gate. Compared with conventional hydraulic steel gate of beam grids, this new style of hydraulic steel gate can save up to 30%-50% of steel consumption. The dynamic behavior of the new gate under the impact load of tidal bore is investigated. The impact load of tidal bore is considered by a load spectrum obtained by field observation over a long period of time. Then a numerical analysis of the gate under the load spectrum is carried out by finite element method. The fluid-structure interaction is considered in the analysis. And a comparison between the response of the gate under the impact load and the response of the gate under the corresponding static load is conducted and indicates that the gate has a dynamic magnification factor of 1.2.

Dynamic Response Analysis of a Floating Mooring System

An innovative floating mooring system with two or more independent floating mooring platforms in the middle and one rigid platform on each side is proposed for improving efficiency and safety in shallow water. For this new system, most of collision energy is absorbed through the displacement of floating platforms. In order to illustrate the validity of the system, a series of model tests were conducted at a scale of 1:40. The coupled motion characteristics of the floating mooring platforms were discussed under regular and irregular waves, and the influences of wave direction and other characteristics on dynamic response of the system were analyzed. The results show that the mooring system is safest at 0° of wave incident angle, whereas the most dangerous mooring state occurs at 90° of wave incident angle. Motion responses increase with the increase of wave height, but are not linearly related to changes in wave height.

夜幕下的宝岭寺

猴年除夕之夜,宝岭寺外工棚。三只满溢节日喜庆的酒杯碰响,一盆吐出蓬勃春意的炭火正红——应佛雕师赵司保和女儿赵心景之邀请,老警“没门”和他们爷俩一块儿吃年夜饭。“没门”是个看一眼就能记住的人:圆脑壳,蒜头鼻,豁牙咧嘴露黑洞,活脱脱一副菩萨尊容。他还是个一人吃饱,全家不饿的人。曾任宝岭派出所头儿的他,一次偶然提前回家,逮住了妻子的奸情。尴尬的是,离所前他还振振有词地调解了一起老婆给老公戴绿帽子的纠纷。

How Does Debt Structure Influence Stock Price Crash Risk?

This paper uses the financial data of Chinese listed firms to explore the relationship between the debt structure, which is measured as the ratio of trade credit to bank loan, and future stock price crash risk. The empirical results show that the ratio of trade credit to bank loan is positively associated with the firm-specific crash risk while a good institutional environment reduces this positive relationship. In addition, considering the firm＇s ownership type, the authors find that the positive relationship between the debt structure and crash risk is more significant in the SOEs.

Influence of thermalization on the initial condition for heavy ion collisions

In this paper,we discuss the important role of the thermalization process in the initial distribution of QGP.We find that the negligible heat conduction inside QGP can be expressed as an effective Fourier law and we further analyse qualitatively the results caused by a thermalized initial condition.Based on this arguments,we construct a simple phenomenological model and work with the hydro code,and then we compare our results with the experimental data and the results of the standard initial model.It is found that,as we have argued,a thermalized initial condition suppresses the value of the elliptic flow.