The hydraulic power-split architecture, or the hydromechanical transmission, can exist in over 1000 configurations. Since a specific hydromechanical transmission configuration has a unique kinematic characteristic, the optimal hydromechanical transmission configuration for one application is different from the optimal hydromechanical transmission configurations for other applications. This study finds the optimal hydromechanical transmission configuration for a hybrid hydraulic city bus. Since a hydromechanical transmission uses at least one planetary gear set, the process of finding a suitable hydromechanical transmission configuration for a hybrid hydraulic city bus is very time consuming, but this study simplifies the procedure by utilizing the critical speed ratio ω_crit, where ω_crit is the missing link between the planetary gear set configuration, its gear ratio and its kinematic characteristic. This simplification also allows complex dual-stage hydromechanical transmission architecture configurations to be considered as candidates for the optimal drivetrain of the hybrid hydraulic city bus. The hydromechanical transmission configuration candidates are simulated over three city bus driving cycles and, to ensure that they operate at the optimal conditions for each driving cycle, dynamic programming is used. This study also establishes two power recirculation modes, one of which is useful because of its high efficiency. A single-stage power-split architecture configuration candidate is found to be the optimal drivetrain for a hydromechanical transmission bus.

Obstacle avoidance is a desirable capability for Unmanned Aerial Systems (UASs)/drones which prevents crashes and reduces pilot fatigue, particularly when operating in the Beyond Visual Line of Sight (BVLOS). In this paper, we present QuickNav, a solution for obstacle detection and avoidance designed to function as a pre-planned onboard navigation system for UAS flying in a known obstacle-cluttered environment. Our method uses a geometrical approach and a predefined safe perimeter (square area) based on Euclidean Geometry for the estimation of intercepting points, as a simple and efficient way to detect obstacles. The square region is treated as the restricted zone that the UAS must avoid entering, therefore providing a perimeter for manoeuvring and arriving at the next waypoints. The proposed algorithm is developed in a MATLAB environment and can be easily translated into other programming languages. The proposed algorithm is tested in scenarios with increasing levels of complexity, demonstrating that the QuickNav algorithm is able to successfully and efficiently generate a series of avoiding waypoints. Furthermore, QuickNav produces shorter distances as compared to those of the brute force method and is able to solve difficult obstacle avoidance problems in fractions of the time and distance required by the other methods. QuickNav can be used to improve the safety and efficiency of UAV missions and can be applied to the deployment of UAVs for surveillance, search and rescue, and delivery operations.

Hydraulic hybrid technology offers superior power density, when compared to competing vehicle hybrid technologies. This allows the hydraulic hybrid vehicle (HHV) to absorb most of the kinetic energy during braking. This paper estimates the fuel economy of a parallel HHV, based on Perodua Myvi passenger vehicle, controlled by a rule-based control strategy. The study simulates the HHV on city and highway drive cycles that are based on Malaysian roads. The simulation results show the parallel HHV offers 39% fuel economy improvement when operates on the city drive cycle and 31% fuel economy improvement on highway drive cycle.

MATEC Web of Conferences, open access proceedings in Materials science, Engineering and Chemistry

This study investigates and optimizes the laser metal deposition (LMD) process for fabricating AlCoCrFeNi_2.1 high entropy alloy (HEA). An orthogonal experiment combined with response surface methodology (RSM) was employed to establish quantitative relationships between key process parameters and melt pool geometry. Results show that laser power (P) predominantly influences the Track width (W), while scanning speed (V) primarily affects the track height (H); both exhibit a coupling effect on the aspect ratio (λ). Regression analysis based on a central composite design (CCD) revealed that the W model achieved excellent fitting accuracy (R² = 0.9997), indicating a strong nonlinear dependence on P. The H model followed a linear trend (R² = 0.7285), whereas λ showed limited predictability. Multi-objective optimization identified the optimal parameters as P = 1100 W and V = 540 mm/min, achieving λ values within the desired range of 2.5–4. Samples produced under optimized conditions exhibited uniform microstructures with refined grains and no visible defects. Mechanical testing demonstrated superior performance, achieving a tensile strength of 877.4 ± 6.3 MPa and an elongation of 4.0 ± 0.18%, alongside uniformly distributed Vickers hardness. These results confirm the reliability of the RSM model and highlight the critical role of energy input in controlling solidification behavior and mechanical response. Overall, this work provides a validated optimization framework for LMD-processed HEAs, offering both theoretical insights and practical guidance for the additive manufacturing of high-performance metallic materials.

Synthetic Jet generates turbulence flow in cooling the microelectronic devices. In this paper, the experiment investigation of the cooling performance of pneumatic synthetic jet with single slot rectangular orifices at low frequency motion is presented. The velocity profile at the end of the orifice was measured and used as characteristic performance of synthetic jet in the present study. Frequencies of synthetic jet and the compressed air pressure supplied to the pneumatic cylinder (1bar to 5bar) were the parameters of the flow measurement. The air velocity of the synthetic jet was measured by using anemometer air flow meter. The maximum air velocity was 0.5 m/s and it occurred at frequency motion of 8 Hz. The optimum compressed air supplied pressure of the synthetic jet study was 4 bar. The cooling performance of synthetic jet at several driven frequencies from 0 Hz to 8 Hz and heat dissipation between 2.5W and 9W were also investigate in the present study. The results showed that the Nusselt number increased and thermal resistance decreased with both frequency and Reynolds number. The lowest thermal resistance was 5.25°C/W and the highest Nusselt number was 13.39 at heat dissipation of 9W and driven frequency of 8Hz.