Applied Mechanics and Materials Vols. 229-231

Abstract: This paper conducts a comprehensive study on the optimization design for crank arc guide bar gathering mechanism of crab claw type loading machine. The optimization aim is to make reality locus of gathering claw end-point be as in-accordance as possible with ideal locus, and so on. Formulae are derived for displacement of gathering claw end-point and position angle of the gathering claw. An optimization design model is established for the crank arc guide bar gathering mechanism. The crank arc guide bar gathering mechanism is optimized of crab claw type loading machine with 2100 mm wide, and the optimization result is satisfactory. Compared to the optimized crank straight line guide bar gathering mechanism in literature [2], the locus error function of gathering claw end-point has been largely improved with a reduction of 25.8%.

Abstract: An open three coordinates computer numerical control (CNC) system was developed, which was based on PC and PMAC motion controller. A three coordinate's miniature CNC milling machine was researched with a simple structure, low cost, small volume and suitability for teaching, and so on. Meanwhile the CNC system had the advantages of 3-axis linkage, program editing, manual operation, inching operation, simulation processing operation, automatic operation and dynamic display of the trace. The system is based on the Windows XP platform and it is convenient to manipulate with friendly interface.

Abstract: To drive multiple parallel-axis to rotate synchronously，this paper put forward a kind of new transmission mechanism——crank-group driving mechanism， introduced the concept of it and its working principles，and demonstrated the feasibility of its movement .

Abstract: The liquid-solid two-phase turbulent flow in an axial flow pump was numerically simulated by using the SIMPLEC algorithm based Navier-Stoker and RNG k-ε turbulent model and after the secondary development of the software Fluent. The distributions of solid concentration, velocity and pressure on the impellers of the axial flow pump were analyzed at different volume concentrations at the pump inlet. The numerical results show that the head and the efficiency of the pump will reduce with the increasing of the sediment concentration in sandy rivers. This research shows that the numerical simulation results are consistent with the actual situations.

Abstract: The bad shunting of track circuit results from the contact resistance between wheel and rail and its solution becomes a disturbing problem for electrical engineer technicians. Based on the Holm electrical contact model, Greenwood model and thermal breakdown theory, this paper analyzed the mechanism of contact resistance between wheel and rail. Then breakdown characteristic of the imperfect electrical layer is analyzed. Through field test, its character is similar to reversed breakdown of diode and the contact resistance decreases as the current ascending. The conclusions of the experiments not only prove the validity of Holm and Greenwood model, but also provide the professional and practical parameters for solving bad shunting. And these parameters involve the breakdown voltage and short-circuit current.

Abstract: Unsteady flow field in a centrifugal pump causes significant radial load on the impeller leading to the vibration in consequence. In order to reduce radial load, a special slope volute was proposed. The full 3D-URANS equations were solved for several flow rates between 60%~150% of rated conditions. The magnitude of average radial load was estimated by empirical formula. It was found that the numerical results agree with the results obtaining from empirical formula quite well. When adopting slope volute, the radial load on the impeller is much smaller compared with conventional spiral volute. So it is convinced that the radial load can be reduced significantly when using slope volute.

Abstract: The evaporator is a critical component when using organic Rankine cycle (ORC) to recover waste heat from an internal combustion engine. Evaluating the amount of heat quantity that can be transferred in a designed evaporator is very important for a successful ORC system. In this paper, a finned tube evaporator used for recovering the exhaust waste heat of a diesel engine was presented. The mathematical model for the evaporator was set up according to the dimensions of the designed evaporator along with the specified working conditions of ORC. The evaporator performance was analyzed as the matched diesel engine operating at the rated power point. The results indicate that the heat transfer quantity of the designed evaporator can be reached at 76 kW, and the exhaust temperature at the evaporator exit can be reduced to 115°C.

Abstract: Kinematics and dynamics of planar 3-RRR parallel robots are presented. Firstly, kinematic equations of planar 3-RRR parallel robots are given. Then, dynamic model of the system based on Lagrange equations is obtained. Finally, the change of the drive torque and energy consumption of active joints are analyzed under the different trajectories and different loads of the moving platform is given, the results showed that the mass and trajectory of the moving platform have a critical influence on drive torque and energy consumption of the active joint. These are very important for the optimum design of the manipulator and the excellent design of the dynamic controller.

Abstract: Incinerator is an important prevent pollution equipment on ship, usually it is used to deal with some combustible rubbish, such as waste food waste, oil dishcloth, especially dirty oil and oil sludge. Through analyze the quantity of dirty oil and oil sludge that produced on ship, and calculate the exhaust gas heat energy that can be used from incinerator, the exhaust gas heat energy has plenty of energy from incinerator, it should be utilized and it will be a new way that to improve ship energy utilization efficiency.

Abstract: This paper presents a high precision position stage which has the movement range of 0.4 micrometer and 1 nanometer precision. The piezoelectric actuator stage is composed of vertical position control part and horizontal position control part. With the three vertical piezoelectric actuators and three horizontal piezoelectric actuators, the stage can adjust the position in three directions and three angles around. The simulation and experimental results show that the first natural frequencies of the stage in three directions are bigger than 400Hz with the 600kg load, which means that the system are very strong to satisfy the stiff requirement. To evaluate the performance of the precision stage, vertical and horizontal movement and resolution are experimented with capacitance type displacement sensor whose sensitivity is 0.1V/um. The results show the stage can satisfy the design requirement.