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Swarm-initialized adaptive controller with beetle antenna searching of wearable lower limb exoskeleton for sit-to-stand and walking motions
No full textIn recent years, exoskeleton robots have attracted great interest from researchers in the area of robotics due to their ability to assist human functionality improvement. A wearable lower limb exoskeleton is aimed at supporting the limb functionality rehabilitation process and to assist physical therapists. Development of a stable and robust control system for multi-joint rehabilitation robots is a challenging task due to their non-linear dynamic systems. This paper presents the development of a Swarm-Initialized Adaptive (SIA) based controller, which is a combination of a swarm-based intelligence, named Swarm Beetle Antenna Searching (SBAS), and an adaptive Lyapunov-based controller. The SBAS initializes the parameters of SIA to efficiently improve the performance of the control system and then these controller parameters are updated by an adaptive controller. The control system is validated in a lower limb exoskeleton prototype with four degrees of freedom, using a healthy human subject for sit-to-stand and walking motions. The experimental results show the applicability of the proposed method and demonstrate that our approach obtained efficient control performance in terms of steady-state error and robustness and can be used for a lower limb exoskeleton to improve human mobility
Speaking anxiety among TVET undergraduates and its implication on graduate employability
Full text linkSpeaking skill is an important predictor in graduate employability. Many job seekers suffer from speaking anxiety and this has affected their job employment opportunities. The focus of this research is to examine the TVET undergraduates’ speech anxiety level and determine what makes them apprehensive when speaking. The study also finds out the anxiety level differences between male and female TVET learners. The 313 research participants who answered McCroskey's Personal Report of Public Speaking Anxiety (PRPSA) questionnaire were undergraduates from a public technical university. The findings revealed that the learners
had moderate levels of speech anxiety (M=115.7) and t-test results indicated that the mean scores for speaking anxiety levels of male and female learners did not differ in a way that was statistically significant though TVET female learners (M=113.30, SD =14.309) experienced slightly higher levels of speaking anxiety compared to their male counterparts (M=111.58, SD=15.996). The idea of giving a speech sent fears to the learners while losing concentration during speech heightened the learners’ speech anxiety level. Higher
learning institutions could include public speaking trainings in their TVET syllabi. Additional soft skills such as public speaking helps ensure TVET graduates become industry priority in the employment market
Review on the air temperature and humidity produce by solar dryer and potential to be reused
Full text linkThis article presents a comprehensive review of recent advancements in the reuse of waste heat from solar food dryers, a strategy that holds significant potential to improve system efficiency and sustainability. Solar drying systems typically discharge air at temperatures between 40°C and 70°C, resulting in a substantial loss of free solar thermal energy up to 50% of total energy. This review introduces novel approaches to capturing and reusing this low-quality heat, including the integration of desiccant materials that can boost drying efficiency by up to 64%, and innovative designs like rotating dryer wheels, which increase effective heat gains by an average of 153%. Unlike previous studies, this article not only aggregates and analyzes field test data such as outlet temperatures, humidity levels, and heat recovery efficiencies but also identifies practical and scalable solutions for heat reuse, such as water heating, space heating, and heating nearby cold rooms. By providing quantitative results and exploring the potential for continuous 24-hour operation through advanced heat management techniques, this review offers new insights and practical guidelines for engineers and researchers aiming to make solar drying processes more energy-efficient and commercially viable. This work is particularly relevant for those interested in developing sustainable agricultural practices, as it highlights the most promising methods for reducing energy waste and enhancing the overall performance of solar dryers. The novel synthesis of existing technologies and the identification of key areas for future research make this article a valuable resource for advancing the field of solar drying
Citizen satisfaction of e-policing system in the UAE
Full text linkIntegrating technology has become a key component of evolving global police operations in the quickly evolving field of law enforcement today. In this regard, the United Arab Emirates is distinguished as a leader in innovation, demonstrating a dedication to technical progress by introducing electronic policing, or e-policing. This study looks into how many aspects affect how satisfied citizens are with e-policing systems, a topic that is becoming more and more important in the digital era. E-policing systems, which use technology to improve law enforcement services, are now necessary to guarantee that the public and police can engage and communicate effectively. The purpose of this study is to pinpoint the precise components of e-policing that have a major impact on citizen satisfaction in order to offer a thorough grasp of the factors that contribute to favorable public impression. Through the use of a robust methodology that includes bootstrapping techniques in SmartPLS 4.0 software and Partial Least Squares Structural Equation Modeling (PLS-SEM), the study looks at how citizen satisfaction is influenced by perceived integrity, transparency, responsiveness, interactivity, serviceability, community engagement, and response time. A standardized questionnaire was utilized to gather data from a randomly chosen sample of participants, guaranteeing an impartial and representative sample for the investigation. Perceived responsiveness, integrity, response time do not significantly affect citizen satisfaction, according to the data, but perceived transparency, interactivity, serviceability, and community engagement conduct significantly. In conclusion, three of the seven direct effect hypotheses integrity, responsiveness, and response time were not supported, while four transparency, interactivity, serviceability, and community engagement were supported. There was no substantial mediation role, as evidenced by the fact that none of the seven demographic segmentation-related hypotheses were supported. These findings highlight how crucial it is for e-policing systems to promote transparent communication, interactive platforms, effective service delivery, and quick reaction times in order to increase public satisfaction and trust. The constructs' validity and reliability were ensured by the establishment of convergent validity, whereby all variables satisfied the criteria for Cronbach's Alpha, Composite Reliability, and Average Variance Extracted (AVE). Through the provision of empirical data on the crucial elements impacting citizen satisfaction with e-policing systems, this study adds to the body of knowledge already in existence. In order to cultivate good attitudes among citizens, it emphasizes the significance of transparency, interactivity, serviceability, response times, and community engagement. In order to raise citizen satisfaction and improve e-policing services, the study provides policymakers and law enforcement organizations with useful ideas. Law enforcement organizations can more effectively serve the communities they serve and better satisfy public expectations by concentrating on these important areas
Intelligent algorithm based modeling of renewable and green energy resources for microgrid optimization
Full text linkThe reduction of fossil fuels, rising oil prices and environmental awareness have attracted attention to the use of renewable energy (RE)-based distributed generation (DG) systems. Among the various types of renewable energy-based DG, photovoltaic (PV) and fuel cell (FC) technology have shown great potential in electricity generation due to rapid technological development, high efficiency, clean operation and slight influence by weather conditions. To ensure optimal DG output, the RE system must be coordinated using a voltage controller and optimisation techniques to determine the optimal DG output voltage and power value. To improve the AC bus arrangement, battery power is connected to a down/up converter to ensure continuous power flow between the Alternating Current (AC) bus and the battery. In order to control the voltage source inverter (VSI) of the PV/fuel cell/battery cell system, conventional methods of control voltage modes and currents with improved controllers of the artificial intelligence (AI) of both the internal current control loop and the output voltage were built. The proposed tuned Artificial Neural Network (ANN) controller has an advantage over the Adaptive Neuro-Fuzzy Inference System (ANFIS) controller while maintaining the simplicity and robustness of the Proportional Integral (PI) controller. The inverter-based DG model is applied to the microgrid system to review its effectiveness as a complete model as well as to evaluate the performance of its use in large network systems. Since the VSI model is built on a P-Q control scheme that allows separate control of active and reactive power output, DG can operate based on active and reactive power reference on the inverter. A new smart technique has been developed to manage active and reactive power reference for DG by using ANN to ensure that the DG unit operates at optimal power values while reducing the amount of power loss as well as maintaining the voltage profile within acceptable limits. The results showed that the proposed tuned ANN technique could accurately predict the active and reactive power references of DG with minimal error. A comparison was made between the ANN DG controller and the ANFIS DG controller for the power management strategy in terms of the generation by standard forecasting metrics. The comparison between the proposed AI controller and the conventional PI controller has been conducted, and the results showed that the proposed tuned artificial NN technique could accurately predict the active and reactive power references of DG with minimal error. For active power of Battery, is 0.23%, Fuel Cell is 0.23%, reactive power of Battery is 0.0175%, Fuel Cell is 0.097%, Photovoltaic PV1, 0.078% and PV2 is 0.021%. At the end of the research, the AI controller was evaluated/validated for effectiveness by comparative means also conducted to assess the performance and forecast accuracy of the tuned AI that has been chosen by forecasting metrics, which show good estimation performance in only 1.6E-14% for the coefficient of determination (R²), 5.86E-05% for root mean square error (RMSE), 9.1E-06% mean absolute error (MAE) and 0.011% for mean absolute percentage error (MAPE)
Big data technology information extraction and fusion from non-homogenous web data sources
Full text linkBig data has played an ever-increasing role in various sectors of the economy. Despite the availability of big data technologies, many companies and organizations in Malaysia remain reluctant to adopt them. This study was conducted to develop a web extraction framework to extract data from the internet to assist adoption of big data technology. Web scrapping has been a popular method for collecting data from websites. This is because data on the internet is updated frequently thus making it a good source for getting accurate information. Analyzing data requires a large quantity of information to yield a good analysis result. However, the non-homogeneous nature of each website may cause the data from the different internet web sources to have different data making the quality of the data inconsistent. Previous study has propose the use of record linkage method to merge data from multiple website. The record linkage method proposed by previous study used deterministic technique to match data which match the string of matching variable to merge data. However, deterministic technique requires the matching variable to be an exact match to be able to match. Therefore, deterministic matching cannot take into account the dissimilarity such as spacing and different letter cases which can be common in web data due to it non￾homogenous nature. This study will explore the use of fuzzy matching technique in matching web data. Fuzzy matching uses Levenshtein distance to calculate the similarity of string and a threshold will be used to decide how similar to trigger a match. This enables fuzzy matching to match string that are only partially match instead of exact match. This study will begin by conducting a systematic review to determine the challenge of big data adoption and what data to extract. This study will implement the Technology-Organization-Environment (TOE) framework to examine the challenges faced by Malaysian organizations with regards to big data adoption. After the systematic review, a web data extraction framework will be developed to extract data that can assist big data adoption. The extracted data will then be merged to enhance the quality of the data. A comparison is made between deterministic matching and fuzzy matching on the performance of merging web data. The finding from this comparison shows that fuzzy matching has a slightly better performance in merging web data. This is due to fuzzy matching can match the string of matching variable that has different spacing and letter cases. A survey case study carried out in this study also shows that the extracted data is very helpful in helping user while purchasing the required big data software on the software market
Studies of corrugated antipodal Vivaldi wideband antenna with notched band and rectenna integration
Full text linkA wideband rectenna based on a Corrugated Antipodal Vivaldi Antenna (AVA) with a notched band is proposed
for energy harvesting applications. The antenna performance is studied parametrically by varying the corrugated and rectangular spiral slot (RSS) structures and also by integrating the antenna with a rectenna for energy harvesting applications. The AVA rectenna achieves an S₁₁ of less than -10 dB from 2.38 GHz to beyond 20 GHz. An AVA with two corrugations at the lower position of the radiator increases the bandwidth by 300 MHz compared to an AVA without corrugation. At 2 GHz, AVAs with three and four corrugations exhibit a directivity of 5.73 dBi, compared to 2.9 dBi for an AVA without corrugation. Increasing the corrugation depth enhances the gain, ranging from 3.05 dBi to 9 dBi. The notched band shifts to lower frequencies as the spiral strip slot lengthens, so we can set the desired notched band by adjusting the length and position of the RSS. Furthermore,
Integration of a rectangular spiral slot (RSS) enables tunable notched bands, providing flexibility to reject interference from unwanted frequency ranges. The agreement between simulation and measurement confirms that the proposed AVA rectenna is also a strong candidate for wideband energy harvesting applications
Quantitative study on the combustion characteristics of water-in-oil emulsion droplets using high-speed imaging technique
No full textUnderstanding the combustion characteristics of fuel droplets is essential for optimizing combustion processes in internal combustion engines and industrial burners. Fuel droplets govern initial fuel-air mixing, vaporization, and combustion, making their study crucial. While previous research suggests that elevated water content in emulsion droplets can lead to increased burning rates, the underlying mechanism remains unclear. Potential contributors including micro-explosions, puffing, sub-droplet ejections, and surface distortions, all of which impacts the burning rates of emulsion fuel. This study aims to investigate the combustion characteristics based on the burning rate and liquid stability of water-in-diesel (WD) and ethanol-in-diesel (ED) emulsion fuels across varying temperatures. High-speed imaging and combustion analysis revealed that WD emulsions exhibit higher burning rates, with evaporation rates increased by 87.35% for WD10, 120.46% for WD20, and 130.66% for WD30 as the temperature rises from 250°C to 350°C. In contrast, ED emulsions showed smaller increases, with rates of 12.33% for ED10, 9.97% for ED20, and 10.31% for ED30 under the same conditions. WD emulsions also experienced larger droplet expansion (D² = 3.3) compared to ED emulsions (D² = 2.97) at 250°C. These findings suggest that WD emulsions, due to their volatile water content, undergo more chaotic combustion characterized by puffing and micro-explosions, while ED emulsions provide more stable combustion behaviour due to the miscibility of ethanol and diesel, which reduces the need for emulsification. This study provides critical insights into the combustion dynamics of WD and ED emulsions, highlighting their potential to improve combustion efficiency and reduce emissions. The results underscore the importance of emulsification in stabilizing combustion for WD fuels and the role of temperature and additive volume in influencing combustion behaviour. These findings contribute to the development of sustainable fuel compositions for industrial applications
Torque ripple minimization of rotating pole piece concentric magnetic gear using rotor skewing and pole piece modification
Full text linkRotating pole piece magnetic gear (RPMG) produces higher average torque than the conventional concentric magnetic gear (CMG). However, it also exhibits a higher torque ripple at the outer rotor as a result of switching of the rotating
component from the outer pole pair (OPP) to the ferromagnetic pole piece (FMP). This paper explores a torque ripple suppression strategy through rotor skewing
applied to the inner pole pair (IPP), outer pole pair (OPP), and ferromagnetic pole piece (FMP). Additionally, this study evaluates the impact of four distinct FMP shapes on the RPMG torque profile. Two gear ratio structures were tested at 4.33 and 5.66 ratio using 2D JMAG Designer finite element software. When skewing was performed on the IPP, it is observed that the inner torque ripple was reduced in both gear ratios when compared to the original structure with a slight drop in average torque for both rotors and gear ratios. Similarly, when smooth shape FMP was used in RPMG, it produced nearly the same average torque and slightly
minimized the torque ripple in both gear ratios versus the original structure. The inner torque ripple was reduced to 2.9% at a 4.33 gear ratio and 4.1% at a 5.66 gear ratio, compared to the original structure. This improvement resulted in a slight average torque decrease of 1-2.5% across both rotors and gear ratios. Theoretically, simulation results have shown that rotor skewing, and FMP shape modification could minimize the torque ripple in RPMG especially at the inner rotor with moderately declined average torque for EV application where minimizing torque ripple is essential for smoother driving experience and reducing mechanical stress on components
Analysis of cascaded H-Bridge multilevel inverters using SPWM with multi-sinusoidal reference
Full text linkMultilevel inverters have become the preferred choice for medium voltage and high-power applications due to their superior waveform quality, reduced stress on switching components, and overall enhanced performance. Among
these, the cascaded H-bridge inverter stands out for its simpler control and modulation techniques, as well as its greater efficiency compared to other multilevel inverter topologies. This paper presents the design and performance evaluation of a cascaded H-bridge multilevel inverter (CHMI)
for five, seven, nine, eleven, thirteen, and fifteen levels, utilizing sinusoidal pulse width modulation (SPWM) in MATLAB Simulink. The proposed technique, the multi-sinusoidal reference, is implemented by comparing multiple sinusoidal wave signals with a carrier triangular signal, with the resulting comparison pulses used to control the inverter's switching. The output results indicate that as the number of levels in multilevel inverters increases, the total harmonic distortion (THD) decreases, and the output voltage improves