Abdul Aziz Nuraini

This paper outlines the conceptual design of a support mechanism developed to improve the lateral stability of electric unicycles (EUCs), specifically the existing Flexi-UC design, during mounting and dismounting without compromising its compact and lightweight features. The study highlights the application of the Theory of Inventive Problem Solving (TRIZ), which enables the mechanism concept to be developed systematically according to the specified design requirements. Several TRIZ tools were applied, namely Functional Analysis, Cause-and-Effect Chain Analysis, Engineering Contradiction, and Physical Contradiction. As a result, Inventive Principle 7, the Nested Doll Principle, was selected and applied in developing the automatic stand design. Finite Element Analysis (FEA) was conducted to verify the automatic stand’s structural reliability. The results showed that the structure could safely support a maximum rider mass of 100 kg. The corresponding load produced a maximum von Mises stress of 66.723 MPa and a maximum deformation of 0.363 mm, both of which are below the allowable limits for mild steel. In addition, theoretical stability analysis indicates that the critical angle increases from ?6.01° without the stand to 10.9° with the automatic stand deployed, providing a significantly wider stability margin. Overall, the results demonstrate that the TRIZ-based approach is an effective method for generating conceptual designs that enhance the lateral stability of the Flexi-UC during mounting and dismounting. ABSTRAK: Kajian ini menekankan aplikasi Teori Penyelesaian Masalah Inventif (TRIZ), membolehkan konsep mekanisme dibangunkan secara sistematik dalam memenuhi keperluan reka bentuk yang ditetapkan. Beberapa kaedah TRIZ telah digunakan iaitu Analisis Fungsi, Analisis Rantaian Sebab dan Akibat, Percanggahan Kejuruteraan dan Percanggahan Fizikal. Hasilnya, Prinsip Rekacipta 7 iaitu Nested Doll telah terpilih dan rekabentuk tongkat automatik telah digunakan. Analisis Unsur Terhingga (FEA) telah dijalankan bagi mengesahkan kebolehpercayaan struktur tongkat automatik tersebut, dan hasil analisis menunjukkan bahawa struktur tersebut mampu menampung beban penunggang maksimum seberat 100 kg dengan selamat. Beban tersebut menghasilkan tegasan Von Mises maksimum sebanyak 66.723 MPa dan ubah bentuk maksimum sebanyak 0.363 mm, kedua-duanya berada di bawah had yang dibenarkan bagi bahan keluli ringan. Selain itu, analisis kestabilan secara teori menunjukkan bahawa sudut kecondongan kritikal meningkat daripada ?6.01° tanpa sokongan tambahan kepada 10.9° dengan penggunaan tongkat automatik, sekaligus memberikan margin kestabilan yang lebih besar. Secara keseluruhan, dapatan kajian menunjukkan bahawa pendekatan berasaskan TRIZ merupakan kaedah berkesan dalam menghasilkan reka bentuk konseptual yang dapat meningkatkan kestabilan lateral Flexi-UC semasa proses naik dan turun.

An increased use of simulation models to solve problems and assist in decision making has led to a doubt on how to access the confidence of the simulation and modelling. Thus, the simulation models are in dire to be verified. Verification is a process of checking the accuracy of the simulation model by comparing with the known solutions. In this study, the computer model of the bus rollover according to Annex 9 UNECE R66 is verified using two methods which is mesh convergence analysis and through the energy balance and ratio. In mesh convergence analysis, it is important to choose the suitable size of the element of the bus superstructure to be used in the simulation to ensure that the bus structure is not too soft or too rigid. Three elements across the ring pillars of 50x50mm square hollow section (SHS) is chosen based on the intrusion into residual space and the amount of the internal energy absorbed. Energy ratio is the ratio of input energy to output which is total energy and must be in the range of 1.00+/- 0.07. The energy ratio obtained is between 0.963 to 1.0148 in this study.

Emissions from internal combustion engines (ICEs) significantly impact the environment, leading continents worldwide to work towards reducing them. The industry is increasingly leaning towards electric powertrains. However, power plants still utilize ICEs as generators, contributing to global pollution. Consequently, ICE emissions are garnering international attention. Alternatives like the Homogeneous Charge Compression Ignition (HCCI) engine and biodiesel fuels are being explored. HCCI engines have not been extensively tested with Used Cooking Oil (UCO) biodiesel. This study investigates the performance and emissions of HCCI engines using UCO-based biodiesel. This study tested an air-cooled, single-cylinder, 4-stroke diesel engine operating at 3600 rpm with a displacement of 0.219 liters. The HCCI mode was activated during preheating and run at 2700 rpm under varying biodiesel blend percentages and intake temperatures. In HCCI mode, brake-specific fuel consumption (BSFC) increased, peaking at a 90°C intake temperature. Diesel fuel in-cylinder pressure reached a maximum of 81 bars at 90°C, decreasing to 79 bars at 70°C. The HCCI mode resulted in lower NOx, CO, and UHC emissions. Higher biodiesel blend ratios further reduced CO emissions. Raising the intake air temperature to 90°C lowered NOx emissions by 96.66%, from 150 ppm to 5 ppm. Using green energy sources as fuel in HCCI engines significantly reduced emissions in this study, suggesting their potential as a future fuel for advanced engines.

For some highly nonlinear problems, the general second-order response surface method (RSM) cannot satisfy the accuracy requirement. To improve accuracy, the highest order number has to be determined in advance. Thus, a progressive trigonometric mixed response surface method (PTMRSM) was proposed to enhance the approximation accuracy and define the highest order number, rather than determining it in advance. After that, a double-loop interval optimization process could be constructed using this PTMRSM to save time while maintaining accuracy when compared to other experimental or computational methods. Unfortunately, the traditional double-loop interval optimization method had issues with the probability of reliable constraints. Then, for the construction of this double-loop interval optimization process, the modified reliable constraints were introduced. A more reliable and effective double-loop interval optimization was introduced for addressing practical engineering problems using the effective approximate method of the PTMRSM and the amended reliable constraints. Two numerical test functions and a composite submersible hull were performed to verify the accuracy and effectiveness of the PTMRSM and the double-loop interval optimization.

MXenes possess unique features that are useful for broader industrial development. However, although many different compositions of MXenes have been discovered, little research has been conducted on the optimal synthesis strategy for producing the best MXenes yield. Therefore, substantial work is performed on the synthesis’ structure and property relationship for direct methanol fuel cell (DMFC) applications since MXenes have been successfully hybridised with rice husk ash (RHA). In this study, to produce titanium-based MXene, Ti₃C₂ nanopowders are added to the rice husk ash matrix to synthesise hybrid RHA/MXene composites (R-MX). Using different weight percentages of MXene hybridised with rice husk ash (2 wt. % R-MX, 4 wt. % R-MX and 6 wt. % R-MX), different electrochemical properties are obtained. Meanwhile, electrochemical analysis is undertaken to investigate the methanol oxidation performance using Linear Sweep Voltammetry (LSV). The highest percentage of the R-MX hybrid composite, 6 wt. % MXene, showed the lowest Tafel slope (148 mV/dec) and the highest ionic exchange current density in the same Tafel analysis. Moreover, the incorporation of MXene into RHA produced good results from the chronoamperometry analysis (CA), with the highest percentage of the hybrid composite, R-6MX, showing the highest retention rate of 97.28%. Meanwhile, the Nyquist plot analysis showed an increasing semicircle arc diameter at the lower-frequency region, implying a lower interfacial charge resistance upon the addition of MXene into RHA. This outcome corresponded to the CA and LSV analysis findings, R-6MX showed a remarkable performance in terms of having the highest peak current density of 0.9454 mA/cm² and retention rate of 97.28%. Both of these values show that hybrid R-6MX was able to maintain a high current for the entire duration. The current is maintained in a stable form for some time, proving that R-6MX was the most stable, with a minimal corrosion reaction and tolerance in a methanol medium. The results from this study enabled an evaluation of the possibility of utilising low-cost, green RHA material for fuel cell applications to promote sustainability. The novelty of this work is that a cheap source of silica-based RHA, a type of waste material, is incorporated with MXene through hybridisation processes.

This article discusses the design and preparation of a modified MXene-based nanocomposite for increasing the power conversion efficiency and long-term stability of perovskite solar cells. The MXene family of materials among 2D nanomaterials has shown considerable promise in enhancing solar cell performance because of their remarkable surface-enhanced characteristics. Firstly, there are a variety of approaches to making MXene-reinforced composites, from solution mixing to powder metallurgy. In addition, their outstanding features, including high electrical conductivity, Young’s modulus, and distinctive shape, make them very advantageous for composite synthesis. In contrast, its excellent chemical stability, electronic conductivity, tunable band gaps, and ion intercalation make it a promising contender for various applications. Photovoltaic devices, which turn sunlight into electricity, are an exciting new area of research for sustainable power. Based on an analysis of recent articles, the hydro-thermal method has been widely used for synthesizing MXene-based nano-composites because of the easiness of fabrication and low cost. Finally, we identify new perspectives for adjusting the performance of MXene for various nanocomposites by controlling the composition of the two-dimensional transition metal MXene phase.

Research on the underground filling mining of Cemented Paste Backfilling (CPB) slurry shows that it alleviates the underground subsidence and environmental problems caused by mining, making a strong contribution to the realization of green mining. To optimize performance, cost reductions, and the recycling of agricultural solid waste, some researchers have studied using volcanic fly ash (FA) to replace part of cement. Corn straw fly ash (CSFA) may be used to replace the same amount of part of cement or FA, as corn straw can improve the mechanical properties of FA to make the CPB slurry for filling goaf. On this basis, in order to ensure a good flow of the CPB slurry in the pipeline, we need to conduct pipeline tests on the slurry of these different cement materials to verify their feasibility. In this article, Fluent has been used to study the CPB slurry transport properties in the two cases mentioned above through numerical simulation. Comparing the velocity distribution and pressure loss changes of the CPB slurry with different proportions in the horizontal pipeline provides a reference for future CPB slurry research. The results show that: (1) FA forms a lubricating layer in the pipe wall due to its "ball effect", which effectively reduces the yield stress and pressure loss of the CPB slurry in the pipe, and plays a positive role in the transportation of CPB in the pipe; and (2) CSFA increases the CPB slurry transport pressure loss due to its irregular particle size, increasing the risk of pipe wear. The results are helpful for better understanding and designing paste filling material for mine.

With the development of coal mining, the use of elbows has diversified the forms of underground backfill pipelines, which has inevitably complicated the transportation characteristics of filling slurry in the pipeline, thus affecting the entire backfilling system. The objective of this study is to numerically investigate the running state of cemented paste backfilling (CPB) slurry and coarse particles at different velocities by transporting in bend pipes. To better understand the transportation state of CPB slurry in pipeline, a computational fluid dynamics (CFD) model—mixture model was developed to study the transportation of CPB slurry. The volume distribution of coarse particles in slurry under different pipe types and different flow rates, as well as the velocity profiles of slurry at different positions, were simulated and analyzed, and the pressure losses under different pipe types were compared. The results show that the distribution of coarse particles varies with the tube type, and the effect of coarse particles on the position of tube wall changes with the increase in velocity. The high-speed zone of CPB slurry will move toward the outer wall of the elbow with the increase in velocity. The pressure loss of CPB slurry in the vertical–horizontal pipeline is larger than that in the horizontal–vertical pipeline, and the difference is larger in the bend section. This study provides a theoretical and meaningful reference for CPB slurry backfilling operations in different bends.

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