A new methodology via using an adaptive fuzzy algorithm to obtain solutions of “Two-dimensional Navier-Stokes equations” (2-D NSE) is presented in this investigation. The design objective is to find two fuzzy solutions to satisfy precisely the 2-D NSE frequently encountered in practical applications. In this study, a rough fuzzy solution is formulated with adjustable parameters firstly, and then, a set of adaptive laws for optimally tuning the free parameters in the consequent parts of the proposed fuzzy solutions are derived from minimizing an error cost function which is the square summation of approximation errors of boundary conditions, continuum equation and Navier-Stokes equations. In addition, elegant approximated error bounds between the exact solution and the proposed fuzzy solution with respect to the number of fuzzy rules and solution errors have also been proven. Furthermore, the error equations in mesh points can be proven to converge to zero for the 2-D NSE with two sufficient conditions.

Aero-engines usually contain a lot of pipes and cables which have an important influence on product performance and reliability. In this paper, a new pipe routing approach for aero-engines is proposed. First, an adaptive octree modeling method is presented according to the characteristics of the layout space. After considering three types of engineering constraints, the total length of pipelines, the total number of bends and the natural frequency of pipelines are modeled as the optimal objective. Then, a Modified Max-Min Ant System optimization algorithm (MMMAS), which uses layered node selection and dynamic update mechanism, is proposed for pipe routing. For branch pipelines, ant colony searches in groups and parallel to improve the solution quality and speed up the convergence greatly. Finally, numerical comparisons with other current approaches in literatures demonstrate the efficiency and effectiveness of the proposed approach. And a case study of pipe routing for aero-engines is conducted to validate this approach.

With good combustion characteristics, hydrogen has been developing as a clean alternative fuel of engines. This study is to develop a diesel/hydrogen dual fuel engine. The hydrogen was added at inlet port in a 4-cylinder direct injection turbocharged diesel engine with an EGR (Exhaust Gas Recirculation) system to investigate engine performance and exhaust pollutant. The measured items are composed of the gas pressure of cylinder, crank angle, consumption rate of diesel, consumption rate of hydrogen, air flow rate, emissions (HC, CO2, NOX, and Smoke), and so on. The authors analyze how the addition of hydrogen with EGR system influences the engine performance and emissions. The diesel/hydrogen dual fuel turbocharged engine can increase the brake thermal efficiency with a greater decrease in emissions compared with the turbocharged diesel engine. Furthermore, the authors little altered the engine structure to get the positive effect of energy saving and pollutant decreasing.

In noise control, the reactance of a mechanical system needs to be minimized while the resistance is chosen suitably. This work illustrates the possibility of and the ease at which such design tasks may be accomplished by utilizing strong electromechanical coupling. Moving-coil loudspeaker is chosen as the vehicle of illustration and it is considered as a simple spring-mass system when operated below its first diaphragm mode. It is shown that the system mechanical property may be tuned easily by a simple R-LC circuit. In addition to the assigned resonance frequency, there can be a maximum of two other resonances. It is argued that the ability to tune the system mechanical resonance to any frequency, such as the ones at very low frequencies, can be very useful for noise and vibration control applications.

This study explored the target sound source location at unknown situation and processed the received signal to determine the location of the target, including the reconstructed signal of source immediately. In this paper, it used triangulation sound sources localization and time reversal method (TRM) to reconstruct the source signals. The purpose is to use a sound source localization method with a simple device to quickly locate the position of the sound source. This method uses the microphone array to measure signal from the target sound source. Then, the sound source location is calculated and is indicated by Cartesian coordinates. The sound source location is then used to evaluate free field impulse response function which can replace the impulse response function used in time-reversal method. This process reduces the computation time greatly which makes possible for a real time source localization and source signal separation.

A physics-based model of residual stress in minimum quantity lubrication (MQL) machining is presented. The stresses resulting from thermal and mechanical loading in the MQL machining process are coupled into an incremental thermal-elastic-plastic model for predicting the final resultant residual stress in the machined workpiece. Comparative analysis is made between the stresses produced by the thermal load and mechanical load in the machining process. Results manifest that for the surface of the machined workpiece, the stress produced by thermal load is on par with the contact stress produced by mechanical load in the magnitude. With the increase of depth into the workpiece, the stress produced by mechanical load is dominant of the total stresses. The rationale demonstrates that thermal load is prone to generate the tensile residual stress at the surface of the machined workpiece, while the mechanical load is prone to generate the compressive residual stress at the surface of the machined workpiece. Finally, the residual stress prediction model is verified by orthogonal cutting of AISI 4130 alloy steel.

The study attempted to observe the surface characteristics of the flank lock type precision locknut which was assembled in a vertical type and operates under different tightening speed. The speed setting was in according with the specifications of 4rpm, 6rpm and 8rpm conditions to set up this experiment. A type of 2TML lubricant was used. The experiment investigated the surface characteristics of a locknut, including contact surface flatness, contact surface roughness, and thread surface roughness before and after the designed test. According to the contact surface flatness of the locknut obtained from this study, it was found that the surface of the locknut contacting with the bearing resulted into a deterioration of the surface flatness and surface roughness during the tests. Furthermore, the thread surface roughness has been changed at different thread for different tightening speed during the test, especially at threads 1, 2, 7 and 8. The study found that some of variations occurred in the values of Ra, Rz and Rmax at different thread of a locknut. The variation of Rmax is the most among them.

The study investigates three-dimensional kinematics of lower limb for female Chinese population during normal squatting activity. 25 young female and 25 elder female Chinese subjects were recruited. With each subject's data collected, the means of three-dimensional rotation angles of knee, hip, and ankle joints of those two groups were calculated and analyzed. Measured results showed that the maximal eccentric range of hip flexion/extension of 128.6° for the young female group (P < 0.05) was compared with that of 158.8° for the elder female group. Thus, the elder female undergoes more hip flexion/extension angles than the young female in the posture of squatting. The mean range of motion (ROM) of knee flexion/extension was 140.2° for the young female group and 138.7° (significant level P > 0.05) for the elder female group. The mean ROM of ankle flexion/extension was 47.90° for the young female group and 31.9° (P > 0.05) for the elder female group. The ROMs obtained in the experiment during squatting were greater than the reported ones achieved after joint arthroplasty. These data may be invaluable in providing designers of lower limb prosthesis with basic mechanical parameters, and assessing the effect of kinematics of low limb on rehabilitation for the Chinese population.

The insert groove geometry is an important part of turning tool design. In this article, a systematic design approach is presented for the chip breaker design in turning. The chip breaking ability of various groove geometry of a turning insert is investigated. The ratio of chip thickness to chip curl radius is taken as the index of chip breaking performance. Taguchi method is applied to analyze the contribution to chip breaking performance of each geometric parameter. Response surface methodology is then used to construct a predictive model evaluating the effect of turning conditions and groove geometry on chip breaking performance. The result of this study shows that the feed rate significantly affects chip breaking performance, and that insert with larger land angle, higher back wall and smaller groove is more effective in chip breaking. Among the parameters of the insert groove, the width of the groove has the greatest contribution to chip breaking than the others. The simulation results and predictions are validated by turning experiments.