Engineering Science & Technology

An Efficient Approach to the Simulation-Based Sensitivity Analysis of Building Performance: OPAT-based LSA and Sobol-based GSA

Masoud Nasouri — 2024-03-25

This work presents a new efficient approach to the simulation-based sensitivity analysis (SBSA) of building performance. To this end, through a new initiative, the whole building energy simulation program EnergyPlus is combined with the local sensitivity analysis (LSA) and global sensitivity analysis (GSA) through the C++ programming language. The developed method is applied to a dwelling house in the hot semi-arid climate region of Iran. Hereupon, the building design parameters including BR, WWR, DSH, CSPT, HSPT, SA_{IN_W}, SA_{Ex_W}, Th_{Ex_W}, ST_win, VT_win, Th_win, and Th_gas-win are adopted as input variables. Moreover, four major building criteria including annual heating energy consumption (AHC), annual cooling energy consumption (ACC), annual lighting energy consumption (ALC), and predicted percentage of dissatisfied (PPD) index are adopted as output variables. The one-parameter-at-a-time (OPAT) as the LSA and Sobol's analysis as the GSA are carried out to explore the behavior of outputs versus inputs changes and to quantify the total sensitivity of outputs-to-inputs (S_T). In the LSA approach, a new sensitivity indicator called the Dispersion Index (DI) is proposed to define the influence of inputs on outputs. The results demonstrate that for our typical building under study, AHC is most sensitive to the HSPT and SA_{Ex_W}, with S_T of respectively 80% and 79%. While ACC is most sensitive to the CSPT and SA_{Ex_W} with S_T of respectively 72% and 63%. Besides, WWR, VT_win, and BR with S_T of respectively 33%, 25%, and 21% are the most influential inputs on the ALC. Furthermore, CSPT, HSPT, SA_{Ex_W}, and WWR with S_T of respectively 81%, 40%, 36%, and 21% are the most influential inputs on the PPD. ALC has no dependence on the CSPT and HSPT of VAV and thermo-physical traits of wall and window. Besides, the sensitivity results obtained by the proposed DI in OPAT-based LSA are in good accordance with the Sobol-based GSA ones.

A Fresh Perspective on the Concatenation Model in Optical Fibers with Kerr Law of Self-Phase Modulation

Anwar Ja'afar Mohamad Jawad — 2024-03-11

The current work revisits the concatenation model having Kerr law of self-phase modulation and takes a fresher look with three different forms of integration technologies. The extended simple equation approach, the tanh-coth method, and the improved modified extended tanh-function approach yielded a spectrum of soliton solutions to the model. These reveal a spectrum of 1-soliton solutions to the model and they are all classified as well. The surface plots are also presented.

Bitter Kola (Garcinia Kola): Exploring Its Uncharted Territory in Polymer Composites-A Pathway to Enhanced Mechanical Attributes and Sustainable Innovation

D. A. Ekpechi — 2024-05-21

This study unveils the hitherto unexplored mechanical attributes and chemical composition of bitter kola (Garcinia kola), shedding light on its promising role as a constituent in polymeric fillers. Three random bitter kola fruits were selected for the experiment. Employing advanced techniques, including Scanning Electron Microscopy (SEM) and mechanical testing, we comprehensively investigated the physico-chemical properties of bitter kola seeds. Our findings revealed a density of 1.2944 g/cm³, a moisture content of 22.3%, a water absorption rate of 4.48%, and a compressive strength of 0.179 MPa for bitter kola. These quantitative results characterize bitter kola and underscore its potential as a valuable material for diverse applications. Moreover, this research bridges the gap between traditional medicine and mechanical engineering, offering a unique perspective on bitter kola's untapped potential. The study opens doors for the development of innovative materials and products with vastly improved mechanical attributes, catering to a wide array of industries. From pharmaceuticals to sustainable packaging, bitter kola's promise extends into multiple sectors, promising groundbreaking advancements.

Simulation of Automotive Components to Optimize Best Application from Different Grades of Steel Using Finite Element Method (FEM)

Amarjeet Kumar Singh — 2024-04-25

The automotive industry has been continuously striving to reduce weight in order to improve fuel efficiency and enhance safety. One approach to achieve this is by utilizing high-strength structural components. With each new model, automotive designers make changes to the structural components and material specifications to enhance efficiency and safety. Due to the availability of various high-strength steels with different formability characteristics, it is important to study and identify the most suitable grade of steel for different critical components. To determine the optimal and cost-effective grade of steel for specific applications, FEA-based models offer a cost-effective solution. In this study, a finite element analysis (FEA) model was developed using PAMSTAMP to simulate the forming process of the B-pillar and hood of a car. This model was used to conduct forming simulations of the B-pillar & hood components using six commonly used advanced high-strength steels (AHSS) in the automotive industry: DP590, DP780, DP980, DP1180, and CP780. The developed model predicted and compared potential crack locations, major/minor strains, stress distribution, and thinning profiles for the selected steel grades. The results revealed that DP590 exhibited a higher tendency for wrinkling, while DP980 and DP1180 showed a propensity for cracking at the bend section due to their lower formability. On the other hand, DP780 and CP780 were found to be ideal for the selected B-pillar & hood design. However, CP780 would require a higher blank force compared to DP780. Currently, this model is being utilized for the development of new steel grades and for assessing the suitability of design specifications offline. This reduces the need for physical experiments and enables more efficient advancements in the field.

Influence of the Height Value of Cylindrical Specimens of Copper Grade M3 on the Kinetics of Their Cooling and Heat Transfer Processes

Z. Nizomov — 2024-04-25

The paper presents the results of the influence of height values on the kinetics of their cooling and heat transfer processes of cylindrical samples made of copper M3 grade with a diameter of 1.0 cm. Characteristic cooling times for these processes are calculated. It is found that the characteristic cooling time increases in the series of radiation, heat conduction, and convection, linearly depending on the ratio of the sample volume to its surface area. Using experimental data on the cooling rate of the samples and theoretically calculated values of heat capacity by the Neumann-Kopp rule, the heat transfer coefficients for the processes of convection, heat conduction, and radiation as a function of temperature are estimated. It was found that with increasing temperature, the coefficients of radiative and conductive heat transfer increase, while the convective heat transfer coefficient decreases. A comparison of the heat transfer coefficients shows that within the experimental error, they do not depend on the sample length.

Mechanical and Thermal Properties of Hybrid Rice Husk/Kenaf Reinforced Polyethylene Terephthalate (PET)/High-Density Polyethylene (HDPE) Blends/Composites

Emmanuel Duniya Kambai — 2024-03-22

Polymer blends offer corrosion resistance, lightweight properties, and toughness, which are vital for fuel economy in the automotive and aerospace sectors. Rice husks and kenaf fiber enhance mechanical and thermal properties, offering cost-effective and eco-friendly reinforcement options. This study aims to incorporate natural fibers such as kenaf and rice husks into a blend of High-Density Polyethylene Blow (HDPEb) and Polyethylene Terephthalate (PET) to fabricate a hybrid composite with enhanced mechanical and thermal properties suitable for automotive applications such as car bumpers. Compression moulding was used for the composite fabrication, while Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), and mechanical and thermal properties of the hybrid composite were determined. SEM analysis elucidates the improved dispersion and interfacial adhesion between the rice husk-kenaf fiber (RK) particles and the polymer matrix. Notably, 30% RH/KENAF hybrid composite exhibits commendable mechanical properties, including a tensile strength of 350.19 MPa, elongation at break of 9.92%, impact strength of 0.228 J/m², average hardness of 64.8 Hv, flexural strength of 70.43 MPa, flexural modulus of 2,838.86 MPa, and an initial decomposition temperature of 693.50 °C, with a final maximum rate of decomposition reaching 800 °C. The results of this work extend to diverse applications, particularly in the automotive industry, where enhanced materials are sought for applications such as replacement parts and car bumpers.

Application of Quantitative Models for Enhancing Supply Chain Efficiency and Mitigating Risks in Water Tank Manufacturing Industry Nigeria

N. I. Ezeaku — 2024-05-24

The study investigates quantitative models for analyzing the supply chain risks associated with a water tank manufacturing company's facility in Aba, Abia State. Aba, renowned for its bustling commercial activities in the southern part of Nigeria, faces challenges in the supply process due to the combined factors of water tank weight and size. This research explores the intricacies of supply chain management, aiming to identify risk assessment models and vulnerabilities, propose optimal scenarios, and recommend improved risk management strategies. Various methods such as risk factor identification, route time estimation, critical path analysis, cost-related risk assessment, comparison of logistic choices, decision tree analysis, and mitigation strategies were employed to determine the most efficient supply path and reduce costs. The analysis reveals that PATH 6 emerges as the most time-efficient route, with a critical path identified at 62 hours. From the result obtained by applying the developed paths to the supply chain mechanism of five major distributors of the company to observe the cost-effectiveness of each path between the budgeted cost, previous cost, and the cost of supplying the goods by following the developed path, which the budgeted cost and paths cost are closely related compared to the previous cost, for Global Chidozie Nzelu (G.C.N) Enterprise, the overall cost reduction from budgeted, actual, and total path costs stood at 7.89% and 9.44%, respectively. Similar trends were observed for St. Chris Global (S.C.G) Limited. (LTD.) (7.04% and 6.34%), Adiliaba Trading Company (A.T.C) LTD (5.76% and 7.31%), Rechard Romeo International (R.R.I) Company (6.07% and 5.46%), and Ndubia Goddy Lines (N.G.L) LTD (5.76% and 7.31%), showing a total reduction of 6.851%. This research empowers the water tank manufacturing company in Aba and Nigeria at large, to optimize its supply chain; furthermore, the implications extend to shaping a more efficient and adaptable landscape for manufacturing industries in the region.

Effect of Radiation on Casson Hybrid Nano-fluid Flow over an Inclined Surface Using Blasius Rayleigh-Stokes Variable: Application in Solar Aircraft

Olayinka Akeem Oladapo — 2024-03-07

Solar energy is the most important heat source from the sun, with photovoltaic cells, solar power plates, photovoltaic lights, and solar pumping water being widely used. This study looks at solar energy analysis and a method for increasing the efficacy of solar aircraft by combining solar and nano-technological energy. To enrich the research on solar aircraft wings, the study is built on the investigation of heat transfer by employing a hybrid nano-fluid past inside the parabolic trough solar collector (PTSC). The thermal source is referred to as the solar radiative flow. The heat transfer efficiency of the wings was validated for different qualities such as porous medium, viscous dissipation, play heating, and thermal energy flow. The modelled energy and momentum equations were controlled by utilizing the Galerkin-weighted residual method (GWRM). This study used two types of nano-solid particles, copper (Cu) and zirconium dioxide (ZrO₂), in ethylene glycol (EG) as the standard fluid. Various control parameters for velocity, temperature outlines, frictional factor, and Nusselt number were explained and shown in figures and tables. Also, analyses reveal that the thermal profile reduces with an increase in variable thermal conductivity parameters. This study will be of considerable economic value to marine engineers, mechanical engineers, physicists, chemical engineers, and others since its application will help them improve their operations. The findings revealed that the magnetic term is positively impacted by the Cu-ZrO₂/EG hybrid nanofluid's thermal distribution.

PiRATe: A Comprehensive Set of Statistical Tests for Evaluation of Quantum Random Number Generators

Soheil Hajibaba — 2024-05-22

As true random numbers are essential for many applications, high-quality Random Number Generators (RNGs) are highly demanded. Several different statistical test suites have been developed to evaluate the quality of RNGs. However, some programming skills are required to work with these statistical tests as they are not available as self-contained software and often are without a Graphical User Interface (GUI). In this work, we have developed PiRATe (Pi Randomness Assessment Test) an easy-to-use wrapper software for the assessment of RNGs using a comprehensive set of statistical tests, including DIEHARDER, NIST SP800-22, NIST SP800-90B, Entropy-Nonlinearity-Test (ENT), Borel Normality, and four Chaitin-Schwartz-Solovay-Strassen tests. We then used PiRATe to evaluate the quality of five different (Commercial and Experimental) Quantum Random Number Generators (QRNGs).

Use of Commercial Starch, Starches Derived from Cassava, Potato, and Yam as Additives for Synthesising Metakaolin-Based Geopolymer Composites

Cedrick Mbiakop Dieuhou — 2024-05-24

The main objective of this work is to investigate the use of different starch sources (yam, sweet potato, cassava, and commercial starch) as additives for the production of metakaolin-based geopolymer composites. Geopolymer composites were prepared by replacing metakaolin with 0 and 15 wt% of each type of starch. The different powders obtained were separately mixed with a hardener containing a molar ratio of SiO₂/Na₂O of 1.6. X-ray diffraction and Fourier transform infrared spectroscopy analysis were used to determine the structural properties. The compressive strength and morphology of the prepared geopolymer composites were investigated. Results show that the reference geopolymer compressive strength is 36.25 MPa. These are 64.66, 48.49, 46.03, and 44.71 MPa when commercial starch, yam starch, cassava starch, and sweet potato starch, respectively have been used as additives. It can be seen that the compressive strength values of the geopolymers containing starches are higher than those of the reference geopolymer. The compressive strength of the geopolymer composite made by replacing metakaolin with commercial starch is higher than those made with yam starch, cassava starch, and sweet potato starch. The X-ray patterns of all the geopolymers show the same mineral and the infrared spectra show the same absorption bands, except for the one at 2,935 cm^-1 which appears on the spectra of the geopolymers containing starch. The geopolymer composite containing commercial starch has a more compact and dense microstructure. Those containing starches from yam, cassava, sweet potato, and the reference geopolymer material have a coarser microstructure. Compressive strength is consistent with the more compact and dense microstructure of geopolymer composite containing commercial starch. The incorporation of 15 wt% of starches derived from yam, cassava, sweet potato, and commercial starch was found to increase compressive strength. It was found that starches from various crops could be used as additives in the synthesis of geopolymer composites.

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

Cedric M. Dieuhou — 2024-03-07

The main objective of the present study is the investigation of the behaviour of starch powder incorporated at different levels (0, 5, 10, 15, 20, 25, and 30 wt%) on the compressive strength and microstructural properties of metakaolin-based geopolymers. Sodium silicate with a molar ratio of SiO₂/Na₂O of 1.6 was used as the hardener and standard metakaolin was used as the aluminosilicate source. The results showed that when metakaolin was replaced by starch from 0 to 15 wt%, the compressive strength increased from 36.50 to 64.12 MPa. When metakaolin was replaced by starch above 15 wt%, the compressive strength decreased from 64.12 to 29.43 MPa. That of the reference geopolymer material is 36.50 MPa.The infrared spectra of the geopolymer composites indicate that the Si-O-C bonds are formed. The thermal behaviour of geopolymer composites containing starch shows a mass loss at around 100 and 278 °C. The geopolymer material without starch only shows a loss of mass at around 100 °C. The micrographs of the geopolymer composite with 15% by weight of starch show that the matrix is more compact, more homogeneous, and denser than the one without starch. On the contrary, possibly due to a large amount of unreacted starch in its network, the micrographs of the geopolymer composite obtained after the incorporation of 30 wt% starch show a heterogeneous microstructure. It can be concluded that suitable starch content for the synthesis of geopolymer composites would be around 15% by weight.

Design and Implementation of a Charge Controller for Solar PV Systems for Emergency Situations in Health Facilities in Rural Areas of Uganda

David Kibirige — 2024-04-25

This paper presents the design and implementation of a solar charge controller system (SCCS) for emergencies in health facilities located in rural areas of Uganda. The SCCS is a Direct Current (DC) voltage regulator and controller that controls the production of power from solar panels and stores the power in battery backup systems. The charge controller reduces the voltage to prevent overcharging of the battery, which reduces its life expectancy. The SCCS also prevents the batteries from over-discharging, protecting the system from electrical overloading. The methodology utilized in this study is clearly outlined, detailing the design and implementation process of the SCCS. The experimental setup and testing show that the SCCS works accurately and low sunlight does not affect its efficiency. The SCCS efficiently protects the system from excessive current flow due to overloading and overvoltage. The average efficiency of the designed renewable energy system is 96.52% over eight days of testing. The SCCS presented in this paper is a cost-effective solution for emergencies in health facilities located in rural areas of Uganda, where access to electricity is limited.

Contribution to the Optimization of the Energy Efficiency of Fixed Collector Panel and Solar Tracking Systems Aimed at Technical-Economic Forecasting

Boaz Wadawa — 2024-04-25

The objective of the study is to establish a decision support and design tool that will minimize the costs of installation and maintenance of solar collection systems while guaranteeing efficient performance. To do this, an algorithm is proposed to first determine the solar radiation on a flat surface with optimal inclinations fixed annually, monthly, and seasonally. Then, secondly, to carry out the evaluation of solar radiation using models of one and two-axis solar tracking systems. In addition, a χ² homogeneity test tool is proposed to predict the techno-economic profitability of several solar collection systems at the same time. It appears that the capture yield by monthly tilt is higher than approximately 1.2% and 0.2% respectively compared to the annual and seasonal fixed tilt methods. Moreover, the capture rate by dual-axis sun tracking is about 19% and 27% higher than single-axis sun tracking methods and fixed optimal tilt methods respectively. According to the χ² test, the two-axis tracking method is the most advantageous from a technical and economic point of view. From the results of the χ² test, we can say by analogy that the performances of the TR-axis, IEW-axis, and V-axis models prove to be more profitable than the two-axis model. However, to avoid the practical difficulties linked to the search for technical-economic compromises, some solar field developers prefer the method of fixed capture of the optimal inclination.

Effect of Size on Cooling Kinetics of Spherical Samples from Different Grades of Aluminum

Z. Nizomov — 2024-05-24

The influence of the size of spherical specimens of different aluminum grades (A0, A5, A6, AB98, and A5N) on their characteristic cooling times and heat transfer coefficients in a wide temperature range has been investigated. It is shown that the cooling process of spherical samples in all cases is carried out by convective and radiative mechanisms of heat exchange with the environment, possessing characteristic times. The values of characteristic times of cooling due to convection and radiation are estimated. Using experimental data on the cooling rate of samples and theoretically calculated values of their heat capacity according to the Neumann-Kopp rule, the coefficients of radiant and convective heat transfer as a function of temperature are determined. It was compared with the regularities of the effect of sample size on the thermophysical properties of cylindrical samples. It is found that spherical specimens cool faster than cylindrical specimens of the same mass, and the heat transfer coefficients are larger. During the experiment, it turned out that the convective heat transfer coefficient lies in the range of 10-20 W/m²·K.

Numerical Approach for Nonlinear Dynamics Simulation of Belt-Pulley XY Positioning Mechanism

M. R. Homaeinezhad — 2024-05-14

In this article, the kinematics and dynamics of the CoreXY mechanism are explored, taking into account the motion of the collar plate. Within such mechanisms, the role of friction in the system dynamics is emphasized, necessitating its careful consideration during the derivation of equations. Friction, manifesting in both static and kinetic forms, can lead to the creation of dead zone regions in the system's operations. These zones are thoroughly discussed in this paper, and friction is accurately computed in various modes across the system components. Among the significant factors contributing to the creation of dead zones are the tension forces within the belts, with their effects on the mechanical dynamics also being meticulously examined. The impact of dead zones on the system dynamics is revealed through simulation results of the dynamic equations, shedding light on the various scenarios in which actuator inputs fall within or outside these dead zone regions. By employing the equations derived from this article, a comprehensive insight can be gained into the prevalent practice of modeling friction-exposed systems, along with a thorough understanding of the dynamic behavior of the CoreXY mechanism.

Condition Synthesis and Performance of Alkali-Activated Composites Incorporating Clay-Based Materials – A Review

Rodrigue Cyriaque Kaze — 2024-05-24

Studies over the years have shown that alkali-activated composite (AAC) binders are viable alternatives to conventional Portland cement (PC) composites. However, the increasing interest in AACs for the construction of various infrastructures has called for a need to find alternatives to the conventional materials used in their production. Various types of 1:1 clay which are available in different forms in different parts of the world can be used as an aluminosilicate source in the production of AACs. However, compared to the use of conventional aluminosilicate sources such as slag and fly ash, there is limited understanding, research, and application of AAC incorporating clay-based materials. Thus, this comprehensive review was carried out to explore and discuss various properties of AACs made with clayey materials. Discussions were made on both the fresh and hardened properties of clay-based AACs. Discussions are held regarding the effects of various alkaline solution types, their concentrations, the combination of various alkaline activators, the fine aggregate to binder ratio, the alkaline solution to binder ratio, and the curing temperature and duration. However, in terms of the hardened properties, more focus was placed on durability performance as these properties are critical to the behaviour of the AACs in various environments.

A Comprehensive Survey of Post-Quantum Cryptography and Its Implications

Bharat S. Rawal — 2024-03-25

Cryptography has been in existence since before the advent of computers. It encompasses a variety of techniques designed to secure information, whether it is at rest or in transit. Symmetric key cryptography includes symmetric keys, which serve the dual purpose of encrypting and decoding communications. Descriptions have been provided for public/private key pairs, also known as asymmetric keys. Such pairs may be categorized as secret/public key pairs, where the private key remains confidential, while the public key is accessible to all relevant parties for communication and information exchange. The realm of private and public key cryptography is diverse. Recently, the National Institute of Standards and Technology (NIST) endorsed four post-quantum cryptography systems. This paper presents a comprehensive survey of cryptography, examining the implications of intricate cryptographic systems on our existing networks.