Study on Dynamic Characteristics of Drill String Considering Rock-Breaking Process

Using various tools to obtain downhole data to reach a precise pore pressure model is an important means to predict overpressure. Most downhole tools are connected to the lower end of drill string and move with it. It is necessary to understand the motion state and dynamic characteristics of drill string, which will affect the use of downhole tools. In this paper, a drilling process considering rock-breaking process in vertical wells is simulated using finite element method. In the simulation, gravity is applied to the whole drill string. The contact force between PDC bit and formation is the weight on bit (WOB). And a rotation speed is applied to the upper end of drill string. Analysis of the results shows that the vibration amplitude of bottom hole WOB (contact force between PDC bit and formation, which is the real WOB in drilling process) is bigger than the amplitude of wellhead WOB (acquired through conversion using Hook load, which is on behalf of the WOB obtained on drilling site). Both wellhead WOB and bottom hole WOB decline with a fluctuation in drilling process. In small initial WOB and low rotation speed conditions, the fluctuation of wellhead WOB focuses on low frequency, the fluctuation of bottom hole WOB focus on high frequency, and the phase of them are not identical. In large initial WOB and high rotation speed conditions, the fluctuation of wellhead WOB and bottom hole WOB both become more irregular. As for wellhead torque and bottom hole torque, the fluctuation of them mainly focuses on low frequency. And in high rotation speed conditions, wellhead torque may become negative. The research results are beneficial to the usage of downhole tools.

Vibration Measurement of a Rotating Shaft using Electrostatic Sensor

Measuring Vibration parameter for rotating machinery is essential for monitoring and diagnosis system in industrial plants. This paper demonstrates another approach to vibration measurement for rotating machine using electrostatic sensor and signal processing techniques. A single electrostatic sensor is used to detect charges surrounding the moving shaft of the machine. The signal from the electrostatic sensor is processed in MATLAB using Autocorrelation, Fast-Fourier, and Root Mean Square. The implementation of this technical approach was conducted on a modified test rig using three different shafts. The three shafts represent three different vibration modes: normal, abnormal, and severe. Each shaft was experimented under low and high rotation speed to observe amplitude and frequency level. Although the results of the tests did not show a direct measure of vibration displacement, due to the complex nature of the induced charges by the surface pattern. However, the results showed an indicative level of vibration at different amplitudes for the three shafts.

The System Modification of Transmission on The RCWS Prototype UGV Robot (Unmanned Ground Vehicle)

An automotive transmission system is a system that has the function for conversion torsion and the rapidity (rotation) from the torsion machine and it has a different rapidity to keep on to the last activator. This conversion changes the high rotation speed becomes lower, but it has more energy conversely. The highest torsion in certain machines generally occurs in a half from the limit from the machine rotation which allowed, while the vehicle needs the highest torsion start from it could be moved. The purpose of this study is to modify the accuracy and the exact transmission, so that the activator transmission which uses a pulley system (part of the automobile chassis) and belt will have a gentle rotation by activator use motor stepper with more energy in it. This machine works by having a battery to supply electricity to the motor stepper, then it is controlled by azimuth and elevation moving control so that transmission of weapon bipod will move with elevation-100 s/d 600 degrees. Azimuth moving control will be pressed so it will move the motor stepper and make the weapon move to 360 degrees. The result of the rotation of the motor will move gently and the comparison between use motor DC gearbox which not really soft at the rotation itself.

Self-powered ammonia synthesis under ambient conditions via N2 discharge driven by Tesla turbine triboelectric nanogenerators

Ammonia synthesis using low-power consumption and eco-friendly methods has attracted increasing attention. Here, based on the Tesla turbine triboelectric nanogenerator (TENG), we designed a simple and effective self-powered ammonia synthesis system by N2 discharge. Under the driving of the simulated waste gas, the Tesla turbine TENG showed high rotation speed and high output. In addition, the performance of two Tesla turbine TENGs with different gas path connections was systematically investigated and discussed. A controllable series-parallel connection with the control of gas supply time was also proposed. Taking advantage of the intrinsic high voltage, corona discharge in a N2 atmosphere was simply realized by a Tesla turbine TENG. With the flow of N2, the generated high-energy plasma can immediately react with water molecules to directly produce ammonia. The self-powered system achieved a yield of 2.14 μg h−1 (0.126 μmol h−1) under ambient conditions, showing great potential for large-scale synthesis.

Effect of grain shape on the dynamics of granular materials in 2D rotating drum

We experimentally investigate the effect of the grain shape on the flow of granular material. The grain shape is modified to highlight the effect of grain circularity on granular flow in a 2D rotating drum. Using a laser cutter, we create particles with decreasing circularity. We observe that the effect of grain shape depends on the rotation speed of the drum. For high rotation speed, granular flow is influenced by the packing’s dilatancy whereas, at low rotation speed, packing fraction seems to influence flowing dynamics. We link these two measurements to grain shape in order to explain its effect on granular flow.

Optimal Design of Cash Circulation Module Gear for Financial Machinery Based on Tribology

To achieve the characteristics of the cash cycle module of a financial machine, such as a compact transmission mechanism, high transmission accuracy, large torque, high rotation speed, high service temperature, no lubrication, and long service life, this work presented a solution to optimize the tooth shape of a thermoplastic gear and the design of a thermoplastic gear with a limit pressure angle of 35°. Through the modeling and simulation analysis of the factors affecting the life of the gear, it was found that the gear with the improved tooth profile was superior to the control gear without the improved tooth profile in terms of sliding wear of the tooth surface, thermal deformation wear, and interference wear. The experimental results demonstrated that the wear resistance of a thermoplastic gear with a tooth profile of 35° was 1.1 times higher than that of the gear with a tooth profile of 20°, which was consistent with the simulation analysis results and can be used as a theoretical basis for thermoplastic gear design in related fields.

Effect of turbulence generator structures to the performance of medium-consistency pump at high rotation speed excesses 2000 rpm

The medium-consistency (MC) pump is the key unit in modern pulp and paper industry, especially in medium-consistency bleaching plant. Use of MC pump improves the efficiency of bleaching sequences and reduces the pollution load of bleaching effluents. In this work, the component of MC pump, e. g. turbulence generators with three typical structures were studied to evaluate the effects of turbulence generator structure on the performance of MC pump. An automatic control system was built to control operation condition and to collect data online. Head and efficiency were calculated to evaluate the differences among three turbulence generators. The results showed that the linear-type, twist-type and screw-type turbulence generators exhibited similar performance (pump head and efficiency) of MC pump at high rotation speed (2000 rpm to 2900 rpm) compared to the well-known performance of MC pump at rotation speed lower than 2000 rpm which are significant different for the three turbulence generators.