Recently, the trend in solar cell research has become highly competitive, with researchers striving to find the best material that strikes a balance between various factors, including fabrication speed, cost, material toxicity, abundance, and overall photovoltaic performance. Typically, cadmium sulfide serves as the buffer layer in CZTS solar cells, but this material is known for its high toxicity. On the other hand, zinc tin oxide (ZTO) has gained popularity in solar cell applications due to its transparency, conductivity, thermal stability, and non-toxic nature. Consequently, the idea of using ZTO as an alternative buffer layer in CZTS solar cells has emerged. In this study, we synthesized nanocomposite thin films of Zn(1−x)SnxO (x = 0.100, 0.133, 0.167, 0.200, and 0.233% w/w) using the sol–gel method and spin coating technique. Among the various concentrations tested, the thin film composed of Zn0.833Sn0.167O demonstrated the highest power conversion efficiency (PCE) of 0.54%. This outcome marked a successful result, indicating that this particular composition optimizes efficiency in our study. It is noteworthy that excessive tin doping did not lead to improved efficiency. However, it is important to acknowledge that the PCE in our experiment is relatively low compared to that of other researchers due to the use of ITO glass as the back contact, chosen for economic considerations. Furthermore, our fabrication method for ZTO thin films resulted in a bandgap energy (Eg) value of 0.78 eV. In summary, our findings suggest that ZTO has the potential to replace cadmium sulfide as the buffer layer in CZTS-based solar cells. These findings are expected to have a significant impact on promoting ZTO as the primary buffer material in CZTS solar cell technology.
An introductory study on simplified aircraft pitch control considering the different variants of the well-known proportional-integral-derivative (PID) controller is presented in this paper. Different control methods have been applied in the aircraft systems control. The linear control methods are not suitable due to highly nonlinear nature of the plant. The intelligent methods lack comprehensive models hampering more rigor research. The nonlinear require higher computing time making their real implementation impossible. The model of the aircraft is a simplified analytical model derived using one of Boeing aircraft models. Investigated are the performances of the PID, PI, and PD controllers. A pulse disturbance was considered to mimic wind, gust, or sudden torque change. Sensor error was considered in the evaluation. The work was achieved by simulation using MATLAB/SIMULINK software. Results showed that PID and PD controllers have similar results while the PI controller has oscillations. Further results show that both the PID and PD are able to suppress the disturbance whose value can result in deviation equals to the reference pitch angle that is; 11° to about 22°. The two controllers however show very poor performance in rejecting sensor errors that is; from 2.2° to just 2°. The PD controller can serve same purpose as the PID controller in aircraft pitch control. Consequently, the study would help to serve as basis for research in aircraft pitch control for beginning as well as new comers and naïve in the area of flight control.
Presented is a study on the application of the reaching law controller for suppressing the effect of backlash disturbance in parabolic antenna systems. The parabolic antennas are reflector antennas specifically designed to work at line-of-sight, otherwise there might be interruption or stoppage of communication. Backlash is one of the interferences that may affect the operation of such systems, and researches deduce that it could be reduced using suitable control systems. This will result in a reduced down time, maintenance costs, handling system complexities and enhanced life span. Many control methods have been tested on such systems ranging from linear methods to non-linear approaches. The antenna model in this study is adopted from a previous work. This study targets the performances of the controller in the presence of backlash disturbance which was then compared with that of the PID controller. The simulation work was done using MATLAB/SIMULINK software. Results portrayed that the Constant Rate Reaching Law Controller (CRC) was able to completely compensate for the disturbance created by the presence of backlash in the system. The PID compensation was not up to that of the CRC. Therefore, the CRC showed better performance in terms of robustness. Furthermore, it indicated the suitability of the scheme for this class of plants; that is parabolic antenna systems. Further studies may aid in achieving simple as well as robust control system for such systems.
One of the issues in manufacturing is implementing the standard for the exchange of product data-numerical control (STEP-NC) data interface model on computer numeric control (CNC) machines. The most often used STEP-NC programming techniques for this implementation are indirect, interpreted, and adaptive. Because of the ease of integration with existing control systems, the performance of the interpreted method was noticeably superior to that of the indirect and adaptive approaches. This concept has resulted in the creation of several tools, systems, designs, algorithms, and methods. In this study, a new STEP-NC implementation system has been created, in which the interpretation has been done using entity-plus string-based (double layer) for more precise data extractions, the tool paths system can create facing, pocket, drill, bore, ream, countersink, side, slot, and contour operations, the output file generation system can create output as per interpreted and hybrid programming approaches, and the execution system can handle multi-threaded operations. To enhance the overall interpretation system and automate implementation by reducing manual intervention, an expert system has also been incorporated. The STEP-NC part 21 examples 1 and 2 part programs were manufactured on the CNC prototype to validate the technology. The creation of the system, the design of the algorithm, the experimental verification, the conclusion, and the future suggestions are described in the paper’s content.
In tubular reactors, fouling issues are caused due to two reasons. One is the heating–cooling prerequisite, and the other is the exothermic nature of the low‐density polyethylene (LDPE) polymerization process. These issues must be considered while optimizing LDPE production to provide maximum productivity and a safe operation. However, it is not a simple process because the conversion of the monomer ( X M ) is generally related to significant profits. This conversion might be performed at high reaction temperatures, resulting in fouling formation. Therefore, in this research, a study of dynamic optimization to find the most efficient production of LDPE in the presence of fouling resistance ( R f ) restrictions is conducted. An R f is employed as a measure of fouling. To establish the highest reactor R f , this study employs variations in the heat transfer coefficient ( U ) calculated from industry data. This dynamic optimization study addresses the optimization challenges using dynopt coded programming based on orthogonal collocation (OC) and sequential quadratic programming methodologies. Beforehand, the LDPE model is validated with industrial data. This study evaluates three possibilities to determine the most optimum reactor performance. The most optimum reactor output is determined from the constrained maximum conversion, which gave 32.15% conversion, while the was effectively met at 47.37cm ² s K/cal.
Authentication is a security function that ensures the system's proper security by identifying and verifying users. Despite the advantages of quantum computers, it is still difficult to enforce authentication on behalf of multiple quantum channel users without the involvement of a third party because present protocols only consider two parties involved in communication. Scalability becomes an issue as the number of parties engaged in the quantum network increases. In addition, an eavesdropper may disguise herself among numerous participants and take advantage of the circumstances to gather information. The authentication method should be used throughout the quantum data exchange process to ensure that the parties participating in the protocol are who they claim to be. The suggested protocol's implementation has been tested using a simulation written in Python. This research aims to propose a protocol for multiparty authentication procedures without the assistance of a third party. The result of the proposed protocol is expected to be a simple and reliable quantum experiment. Importantly, this protocol can establish an environment that is more secure in terms of authentication and allows numerous parties to communicate freely and openly.
Recently, the trend of circular economy innovation (CEI) drive SMEs to initiate more sustainable practices to attain market competitiveness but rare attention has been paid in emerging economies. Hence, this study plans to explore the impacts of CEI on the triple bottom lines (TBL) efficiencies in the light of market competitiveness among the production SMEs in emerging economies. The study complied data by using a survey-based technique in Pakistan, Malaysia, and China. With a sample of 306 for each segment, data were evaluated with PLS-SEM to clarify results. The findings reveal that CEI has positive significant effects on the market competitiveness and TBL efficiencies among the production SMEs in emerging economies. The findings also clarify that market competitiveness mediates the relationship between CEI and the TBL efficiencies. The findings elaborate the theoretical foundations for environmental-based production SMEs to formulate more sustainable strategies in the light of CEI to gain market competitiveness. It also clarifies the understandings of policy makers and environmental regulators by providing a novel precursor to frame the environment-based TBL guidelines for SMEs. It adds to the UN sustainability agenda by elevating the role of CEI as a novel domain among emerging economies grounded on the resource-based view theory.
This research focuses on the manufacture of nano Rice Husk Ash (nRHA) by ball milling technique and critically analyzes the effect of milling time on particle size. The process starts with collection of raw rice husk from a local rice mill factory, followed by controlled incineration at a temperature of 700°C for 5 hours to get the amorphous RHA. Finally, the nano RHA is prepared by subjecting the RHA to grinding for the different period like 10, 20, 30, and 40 hrs. The particle size was analyzed with FESEM, and it was found that particles got smaller as grinding proceeded, reaching an optimal size of 28 nm following 30 h grinding. Nonetheless, prolonged grinding resulted into particle agglomeration that was caused by Van der Waal forces. Therefore, these findings are significant in that they help to comprehend the morphology changes and particle size alterations in nRHA that may be applied for different uses such sustainable construction materials.
Anisotropic flow characteristics in single-fractured tensile and shear fractures of granite subjected to various confining stress were investigated by experiments and experimental results-based flow simulations. Anisotropic characteristics in aspects like permeability reduction rate, stress dependency of permeability, flow path in fracture and fracture aperture distribution were analyzed and compared between tensile and shear fractures. The main conclusions are as follows: (1) for tensile fracture, k X is slightly lower than k Y , the average permeability anisotropic coefficient α k ( α k = k X / k Y ) is in the range of 0.236∼0.779. For shear fracture, k X is obviously lower than k Y , α k is in the range of 0.038∼0.163, therefore, the permeability anisotropy in shear fracture is stronger than tensile fracture. (2) Strong channeling effect exists in both shear and tensile fractures. The stress dependence coefficient of permeability is 0.731MPa ⁻¹ in X direction and 0.365MPa ⁻¹ in Y direction for tensile fracture and this data is 0.034 and 0.010MPa ⁻¹ respectively for shear fracture, indicating that the dependency of permeability on stress also shows anisotropic. (3) An empirical model of α k based on stress and fracture aperture variogram was proposed. Based on α k , permeability along both X and Y directions can be predicted well, especially under relatively high confining stress.
This article explores heat transfer characteristics of magnetohydrodynamics water-base silver (Ag) and iron oxide (Fe 3 O 4 ) hybrid nanomaterials flow in a Darcy-Forchheimer porous medium induced by a stretching/shrinking surface with impacts of heat sink/source. Moreover, thermal radiation effects and the slip boundary conditions are also incorporated in the given problem. Governing partial differential equations (PDEs) are first altered into the ordinary differential equations (ODEs) using suitable similarity transformations. These achieved ODEs are solved by the well-known shooting technique in Maple software to get the required numerical solutions for the variation in different physical parameters. Here, the numerical findings show duality in solutions in case of stretching/shrinking parameter over different ranges of the comprised distinguished parameters. In this regard, the stability analysis is done and the first solution is found stable and physically acceptable, while the second one unstable and physically infeasible. Besides, the skin friction increases for the case of shrinking but it decreases for case of stretching parameter due to the greater impacts of the mass transfer parameter while the heat transfer phenomenon upsurges for the case of shrinking parameter. Moreover, the skin friction, and the heat transfer rise with variation of the suction parameters when the quantity of solid nanoparticles volume fraction is increased.
The neural network is one of the techniques used to enhance the bit error rate performance in communication systems. The wireless communication system usually follows the standard Gaussian distribution, while the noise in underwater acoustic systems usually follows non-Gaussian distribution and leads the system to a high bit error rate value. In this paper, the deep forward neural network has been adopted to improve the bit error rate of the underwater aquatic system based on t-distribution. Furthermore, the parameters of the deep neural network, number of nodes, number of layers, and activation functions have been evaluated to note the behavior of the bit error rate performance of the system. The results show that the bit error rate value of the system declines when increasing the number of nodes and layers in the neural network, while the tanh activation function is a suitable function that can be used to improve the bit error rate performance of the system. Moreover, the complexity and latency pattern of the system increases by boosting the number of nodes and layers of the neural network.
There are at least four families of rodents identified in Peninsular Malaysia namely Muridae, Sciuridae, Hystricidae, and Rhyzomidae. Although rodents are widespread throughout Peninsular Malaysia, information on rodents at Padang Chong Forest Reserve (PCFR) is scarce. Therefore, the main objective of this study is to identify and document the species composition of rodents at PCFR. Samplings were carried out at two plots along the gradient from the border of PCFR namely Plot 1 (500m) and Plot 2 (1km). The size of the respective plot is 1ha with 10 transect lines (AJ), 100m in length separately. These plots were sampled for five times from June to November 2022. Based on this study, a total of 65 individuals from nine species of rodent were documented. These nine species were identified from two families namely, Muridae (5 spp) and Sciuridae (4 spp). Of these, Leopoldamys sabanus was recorded as the highest captured species (25 individuals), followed by Maxomys whiteheadi (19 individuals) and Callosciurus notatus (7 individuals). There is no significant difference in terms of species composition between these plots, Plot 1 (n=33) and Plot 2 (n=32), which further supported by t-test value result (t-test=0.928; p(value)> 0.05). However, there is a single representative of Sundamys muelleri captured in Plot 1 which prefers the riverine area (around 10m). Callosciurus notatus were captured most in Plot 2 (6 individuals) compared to Plot 1 (1 individual). Certain areas nearby to Plot 2 were opened for agricultural purposes which explained the existence of this species at Plot 2. From this information, it is hoped that further actions can be taken to conserve the area to ensure the small mammal communities are preserved.
Lactococcus lactis is a beneficial lactic acid bacterium commonly studied for its probiotic properties and role in dairy production. Here, we present a complete genome of Lactococcus lactis D1_2, isolated from peat swamp forests. To discover the potential antimicrobial properties, the complete genome of the strain was sequenced and analyzed.
The characteristics of nanomaterials have garnered significant attention in recent research on natural and forced convection. This study focuses on the forced convection characteristics of ternary nanofluids within convergent and divergent channels. The ternary nanofluid comprises titanium oxide (TiO 2), zinc oxide (ZnO), and silver suspended in water, which serves as the base fluid. Using COMSOL Multiphysics 6.0, a reliable software for finite element analysis, numerical simulations were conducted for steady and incompressible two-dimensional flow. Reynolds numbers varying from 100 to 800 were employed to investigate forced convection. Additionally, we explored aspect ratios (channel height divided by the height of the convergent or divergent section) of −0.4, −0.2, 0, 0.2, and 0.4. Our findings revealed that only at aspect ratio a = 0.4 did the average outlet temperature increase as the Reynolds number rose, while other aspect ratios exhibited decreasing average temperatures with declining Reynolds numbers. Moreover, as the Reynolds number increased from 100 to 800 and the total volume fraction of the ternary nanofluids ranged from 0.003 to 0.15, there was a significant 100% enhancement in the average Nusselt number. For clarity, this article briefly presents essential information, such as the study's numerical nature, fluid properties (constant-property fluid), and the methodology (COMSOL Multiphysics 6.0, finite element analysis). Key conclusions are highlighted to enable readers to grasp the main outcomes at a glance. These details are also adequately covered in the manuscript to facilitate a comprehensive understanding of the research. The utilization of this emerging phenomenon holds immense potential in various applications, ranging from the development of highly efficient heat exchangers to the optimization of thermal energy systems. This phenomenon can be harnessed in scenarios in which effective cost management in thermal production is a critical consideration.
Refactoring, a widely adopted technique, has proven effective in facilitating and reducing maintenance activities and costs. Nonetheless, the effects of applying refactoring techniques on software quality exhibit inconsistencies and contradictions, leading to conflicting evidence on their overall benefit. Consequently, software developers face challenges in leveraging these techniques to improve software quality. Moreover, the absence of a categorization model hampers developers’ ability to decide the most suitable refactoring techniques for improving software quality, considering specific design goals. Thus, this study aims to propose a novel refactoring categorization model that categorizes techniques based on their measurable impacts on internal quality attributes. Initially, the most common refactoring techniques used by software practitioners were identified. Subsequently, an experimental study was conducted using five case studies to measure the impacts of refactoring techniques on internal quality attributes. A subsequent multi-case analysis was conducted to analyze these effects across the case studies. The proposed model was developed based on the experimental study results and the subsequent multi-case analysis. The model categorizes refactoring techniques into green, yellow, and red categories. The proposed model, by acting as a guideline, assists developers in understanding the effects of each refactoring technique on quality attributes, allowing them to select appropriate techniques to improve specific quality attributes. Compared to existing studies, the proposed model emerges superior by offering a more granular categorization (green, yellow, and red categories), and its range is wide (including ten refactoring techniques and eleven internal quality attributes). Such granularity not only equips developers with an in-depth understanding of each technique’s impact but also fosters informed decision-making. In addition, the proposed model outperforms current studies and offers a more nuanced understanding, explicitly highlighting areas of strength and concern for each refactoring technique. This enhancement aids developers in better grasping the implications of each refactoring technique on quality attributes. As a result, the model simplifies the decision-making process for developers, saving time and effort that would otherwise be spent weighing the benefits and drawbacks of various refactoring techniques. Furthermore, it has the potential to help reduce maintenance activities and associated costs.
I am a woman microwave engineer ( Figure 1 ) and associate professor at Universiti Tun Hussein Onn Malaysia (UTHM) and a member of the Women in Microwaves (WIM) subcommittee of the IEEE Microwave Theory and Technology Society (MTT-S). I received a degree in electrical communication engineering from Universiti Teknologi Malaysia in 2001, a master’s degree from UTHM in 2003, and a Ph.D. degree from the Queen’s University of Belfast, U.K., in 2011. I have also been involved in the organizing committees for various conferences, and I was chair of the IEEE AP/MTT/EMC Malaysia Section in 2017–2020. I have served on the MTT-S WIM subcommittee since 2018 and have actively initiated discussions related to women in microwave engineering in Malaysia. Recently, I became involved with a community service related project funded under an IEEE Humanitarian Activities Committee project.
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