Enhancing mechanical properties of aluminum foam through optimized artificial aging: temperature and time effects

This research focuses on optimizing artificial aging parameters to enhance the mechanical properties of aluminum foam, specifically targeting industries where lightweight yet durable materials are critical. The primary object of this study is to identify optimal temperature and time conditions during artificial aging that will improve the foam’s hardness and compressive strength. The problem addressed is the variability in mechanical properties caused by inconsistent aging parameters, which affect the performance of aluminum foam in high-stress applications such as aerospace and automotive industries. Using Response Surface Methodology (RSM) and a Central Composite Design (CCD), the study systematically examines the effects of aging temperature and time on aluminum foam. A total of 13 experimental runs were conducted to observe the interaction of these parameters. Results obtained through ANOVA analysis reveal that temperature has a more substantial effect on foam hardness than time. The optimal conditions for aging were determined to be 165 °C for 2 hours, resulting in a hardness of 62.4 HV and compressive strength of 2.512 N/mm2. The findings are explained by the formation of fine, uniformly distributed precipitates at lower temperatures and shorter durations, which block dislocation motion and enhance material strength. In contrast, over-aging at higher temperatures leads to precipitate coarsening, which reduces the foam’s mechanical properties. The results of this study provide valuable insights for industries requiring materials with high strength-to-weight ratios, such as aerospace and automotive sectors, where aluminum foam can be used for structural components and energy absorption

Low-voltage temperature-insensitive logarithmic and exponential function current generators using only npn transistors

The continuing reduction of supply voltage for reliable operation of analog integrated circuits is widely recognized. Analog circuits must adhere to this trend. As a result, researchers are currently developing low-voltage analog circuit methodologies. Current-mode signal processing circuits are examples of these concepts. Therefore, the objective of this work is to present circuit realizations of low-voltage current-mode logarithmic and exponential function generators with temperature compensation. Both the input and output signals operate in current mode. The design approach utilizes the current-mode translinear technique to produce the output currents that exhibit a directly proportionality to the absolute values of the logarithmic and exponential functions. By simply adjusting the external bias currents, one can electronically tune the output currents and transfer current gains for both proposed circuits. The proposed circuits utilize only npn bipolar transistors and can operate with low-level supply voltages of ±1V, which are appropriate for low-power, high-frequency applications. Nonideality performance considerations are also discussed in detail. In order to verify the operational function of the circuits and illustrate their superior thermal stability, the PSPICE simulation has been performed using real transistor models provided for the HFA3096 mixed bipolar array technology. The simulation findings illustrate that the proposed logarithmic and exponential amplifier circuits can compensate for temperature variations, as evidenced by the good stability of their output currents over a temperature range of -40 °C to 100 °C

The development of a fully balanced active-RC low-pass filter

This research presents the comprehensive development and analysis of a fully balanced active-RC low-pass filter, specifically designed to deliver high efficiency, tunability, and precision in signal processing applications. The filter architecture comprises four bipolar junction transistors (BJTs) as active elements, connected to two resistors (RL and Ree) and one capacitor as passive components, ensuring a robust configuration. This balanced design facilitates the generation of high-resolution and stable signals, with circuit performance closely aligning with simulation results obtained using the PSpice program. By methodically adjusting the bias current (If), capacitance (C), and resistance values (RL and Ree), the operating frequency (f0) of the filter can be finely tuned to meet specific application requirements. The results indicate that the transfer function exhibits a response of approximately –37.00 dB, with a phase shift of –45 degrees. Further analysis reveals that the operating frequency (f0) can be effectively increased by reducing the values of the capacitor (C) and the resistors (RL and Ree). Additionally, the total harmonic distortion (THD) of the output waveform was measured at 9.563 % using fast Fourier transform (FFT) analysis, demonstrating the filter’s capacity to maintain signal integrity. Key highlights of the fully balanced active-RC low-pass filter include high efficiency, flexible tuning capabilities, and accurate performance evaluation through simulation. Suggestions for future development focus on optimizing the filter to minimize THD, testing performance under various environmental conditions, exploring circuit integration for specialized applications, and investigating potential uses in digital signal processing system

Verification of artillery systems' shots: selection of the most appropriate sensors based on the fuzzy evaluation model

Long-range artillery remains vital in modern warfare, where precision and innovative methods are key to completing fire missions with fewer rounds. Developing advanced techniques of artillery shots verification based on sensor systems that maximize target destruction with minimal ammunition and exposure time is essential for maintaining the combat effectiveness of artillery units. Moreover, one of the complex and important tasks that must be solved in the verification process before each shot is to determine the optimal combination of three sensors from the entire available set included in the sensor system in the firing zone. To solve this problem the paper introduces an approach for selecting the three most appropriate acoustic sensors for artillery shot verification using a fuzzy evaluation model. The approach considers location, measurement error, and probability of failure-free operation at selecting sensors to effectively register ballistic and muzzle waves, with further assessment of the suitability of each sensor. For adequate assessment of acoustic sensors, the presented approach uses a developed fuzzy logic model that allows calculating the value of the sensor suitability criterion for the verification of the current artillery shot. A computational experiment with fixed artillery shot parameters was conducted to evaluate the proposed approach and fuzzy model, successfully identifying three optimal acoustic sensors for precise recording of ballistic and muzzle waves. The obtained results confirm the effectiveness and feasibility of the proposed approach and fuzzy model for selecting the best sensors for artillery shot verification and determining projectile impact coordinates under random disturbances

Optimized GMAW parameters for enhancing mechanical properties of dissimilar AA6061 and AA7075 alloy welds using hybrid ANN-GA approach

Connecting aluminum alloys AA6061 and AA7075 presents significant challenges due to differences in thermal behaviors and metallurgical characteristics, often causing issues like cracking or warping during welding. Gas Metal Arc Welding (GMAW) is commonly used for aluminum alloys, but optimizing welding parameters for high-quality joints remains complex. Traditional methods are often inefficient and inadequate in multi-objective scenarios. Recent advancements in artificial intelligence (AI) offer promising alternatives, but applying AI in GMAW optimization for dissimilar aluminum alloys is still in the early stages. This study uses a hybrid Artificial Neural Network-Genetic Algorithm (ANN-GA) model to optimize GMAW parameters for these alloys, addressing gaps in traditional approaches. The ANN model, trained on experimental data, predicts tensile strength and hardness, while GA optimizes key welding parameters, including current, speed, and wire feed rate, to improve joint performance. The ANN-GA model achieved optimal settings, reaching a peak tensile strength of 237.47 MPa and maximum hardness of 98.72 HV, substantially enhancing the mechanical properties of the welded joints. These findings underscore the effectiveness of the hybrid ANN-GA approach in GMAW process optimization for dissimilar aluminum alloys. This study advances welding technology and establishes a strong framework for applying AI-driven optimization techniques to complex manufacturing processes. These insights provide valuable guidance for improving weld quality in industrial applications and pave the way for further integration of AI techniques to enhance welding performanc

Train timetable design under passenger demand using skip-stop plans for a new railway transportation in express train service from Ban Phai to Nakhon Phanom

The transportation system is a key component of Thailand's infrastructure improvements. In this study, let’s concentrate on the new railway line from Ban Phai District, Khon Kaen Province, to the third Thai-Lao Friendship Bridge, Nakhon Phanom Province. This new double-track railway line project will connect the old railway lines from Bangkok that are upgrading single-track railways to double-track systems. After completing a feasibility study and technical suitability for this railway line, the State Railway of Thailand has commenced construction, with an expected completion date of 2027. However, the feasibility study and technical suitability for this railway line have not yet taken into account the number of passengers and the number of train services. The objective of this research is to investigate the optimal balance between passenger demand and the number of express train services to maximize service capacity using skip-stop strategies. The skip-stop plan offers trains the opportunity to bypass certain stations. By concentrating service on stations with high demand, this method aims to cut travel times and prevent overcrowding. The simulation results show that the all-stop pattern causes the number of passengers loaded onto the train to exceed the express train capacity, but the introduction of the stop-skipping strategy using integer linear programming (ILP) can effectively reduce the number of unserved passengers than stopping at every station when there is a passenger capacity constraint per train. This skip-stop strategy can be an alternative solution for planning other future new railways services when capacity constraints of passenger volume and number of trains are limited

Prospects for the creation of small-sized high-speed unmanned aerial vehicles based on WIG-craft

WIG-craft are high-speed vehicles that use the dynamic principle of support above the ground. Today, the current examples and projects of such vessels concern, mainly, only large-sized or medium-sized manned vehicles, for which it is possible to ensure stable aerodynamic characteristics during flight. At the same time, modern trends in the development of vehicles indicate a growing interest in small unmanned vehicles. Currently, the issue of creating small manned and unmanned WIG-crafts has become relevant. In the presented work, based on the von Karman–Gabrielli methodology, the efficiency of transport WIG-craft among other types of vehicles was evaluated. The possibility of using such small-sized devices as unmanned devices is considered. The productivity of a WIG-craft is depends on its aerodynamic characteristics. Scale factor is very important for WIG-craft, because the aerodynamics is depended on wings size. The design of a small-sized WIG-craft based on the aerodynamic scheme of an airplane is proposed. The aerodynamic characteristics of the proposed device were evaluated using CFD modeling. Outcomes indicates that the aerodynamic properties of a ship are greatly affected by clearance and velocity. Ground effect is allowed to increase the aerodynamic quality up to 1.5 times, provide the transport of payloads at velocities as high as 250 km/h with a take-off weight of 2.7 tons. The analysis of computation results shows that the proposed project of an unmanned WIG-craft is fully operational and promising for solving the problems of high-speed delivery of small payloads. According to the computation results of the aerodynamic characteristics, the specific power of the device was determined, which indicates the high theoretical efficiency of the proposed means

VIOLATION OF PUBLISHING ETHICS. Robust tracking control for twin rotor multiple-input multiple-output system modelled by uncertain fully-actuated mechanical form with additive disturbances

 VIOLATION OF PUBLISHING ETHICSTRMS finds applications across various fields, including aerospace, robotics, education, and research. In control system development field, TRMS provides an excellent platform for developing and testing control algorithms due to its nonlinear and coupled dynamics. This research aims to develop a robust tracking control approach for twin rotor multiple-input multiple-output system (TRMS). First, the model of TRMS is written in the space state of uncertain fully-actuated mechanical form with additive disturbances caused by existence of measurement errors, payload variations, and external disturbances. The robust controller is then designed using the sign function and auxiliary controller to ensure that the closed system including TRMS system and robust controller is always adjusted so that the position-tracking errors tend to the origin, the closed-loop system is globally robust and stable with the lumped system uncertainties caused by modeling errors, the aerodynamic coupling between the vertical and horizontal movements, and friction forces that affect the motions of TRMS. The advantages of this method are a fast transient period, high precision, and strong robustness, and without the adaptive mechanism, it can be applied widely to practical applications such as high nonlinear systems, robotic manipulators, and rigid spacecraft attitude control systems. Finally, to show the advantages this control method is applied to the angles tracking control problem of TRMS which has high nonlinear characteristics, input torque disturbances, and the coupling between the vertical and horizontal movements. The experimental results are presented with the choosing of parameters as nominal parameters that validate the proposed solution. The prominent advantages of this method include a zero percent overshoot, a transient response time of approximately 1s for the yaw angle and 1.5 s for the pitch angle, and superior impulse disturbance rejection compared to linear control. Specifically, the proposed controller stabilizes the pitch angle to its desired initial value within 1s, while the stabilization time for the yaw angle is also 1 s

Assessment of Azerbaijan's geothermal potential for enhanced greenhouse heating systems

The appropriate use of geothermal energy, a notable renewable resource, presents considerable potential for greenhouse heating, particularly in areas such as Azerbaijan, which has abundant geothermal resources. This article examines the utilization of geothermal energy for greenhouse heating, emphasizing the technical and economic advantages, notably in Azerbaijan's geothermal-abundant regions including Lankaran, Khudat, and Absheron. The research offers a comprehensive examination of a suggested greenhouse heating system that combines geothermal energy with solar power, with the objective of optimizing energy efficiency and diminishing dependence on fossil fuels. Significant findings include the ability of hybrid systems to achieve up to 85 % thermal efficiency and reduce greenhouse energy consumption by 30 %. For example, the Talysh region’s geothermal water, operating between 30–64 °C with a flow rate of 14,404 m3/day, can support substantial greenhouse operations. Geothermal integration in Khachmaz sustains consistent heating for 3 hectares of greenhouse space, aligning with global benchmarks from nations such as Iceland, the Netherlands, and Turkey, which have successfully reduced energy usage and carbon emissions. This report emphasizes the significance of utilizing Azerbaijan's geothermal potential to enhance sustainable farming practices. The study offers a thorough examination of current geothermal resources, recent technological innovations, and a meticulously organized proposed system, yielding significant insights into the future of greenhouse heating in Azerbaijan and promoting the wider implementation of renewable energy solutions in agriculture

Experiments comparing the efficency between watering vegetable crops with traditional methods and automatic watering systems

This article experiments comparing the efficiency between watering vegetable crops with traditional methods and automatic watering systems. Objectives: 1. To study the operation of sensors, including temperature and relative humidity sensors and soil moisture sensors. 2. To compare the conventional irrigation of crops with automatic irrigation and to assess the satisfaction of 5 farmers. This is to be used as information to support farmers' decisions. In smart agriculture that is on the rise around the world. Install 1 Relative Temperature and Humidity Sensor (AM2315 I2C) to measure air temperature and humidity values converted into digital signals. Transmit via Wi-Fi signal to the WeMos Arduno UNoR3+ microcontroller ESP8266, and 1 capacitive moisture sensor that sends an analog signal to the WeMos Arduno UNoR3+ESP8266 microcontroller. Experiments are carried out in greenhouses for growing vegetables measuring 6x3 meters. Results: 1. Automatic irrigation of the house with sensors. By experimenting with growing white cabbage, it was found that the temperature control was at an average of 37 degrees Celsius. Average relative humidity inside greenhouses 52.3 %, average soil moisture retention 55 %. 2. The results of the questionnaire of 5 farmers showed that the conventional irrigation of crops had an average value of 1.68 and an S.D value of 0.42. Irrigation with automation. The average value is 4.84 and the S.D value is 0.29, which shows that the irrigation system is automated. Efficient work shortening the working time can solve the problem of changing global climate conditions. This makes it easy for farmers to make decisions when choosing to use the automation system