Search results for: mixed integer non-linear programming

Authors: Lv Shizeng, Han Xiao, Zhang Yi, Ding Wenjing

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The lunar sample storage device is mainly used for the preparation of the lunar samples, observation, physical analysis and other work. The lunar samples and operating equipment are placed directly inside the storage device. The inside of the storage device is a high purity nitrogen environment to ensure that the sample is not contaminated by the Earth's environment. In order to ensure that the water and oxygen indicators in the storage device meet the sample requirements, a dynamic gas cycle is required between the storage device and the external purification equipment. However, the internal gas disturbance in the storage device can affect the operation of the sample. In this paper, the storage device model is established, and the tetrahedral mesh is established by Tetra/Mixed method. The influence of different inlet position and gas flow on the internal flow field disturbance is calculated, and the disturbed flow area should be avoided during the sampling operation.

Keywords: lunar samples, gas disturbance, storage device, characteristic analysis

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Authors: Hamid Ahmadi, Neda Azari Dodaran

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This paper aims to study the structural behavior of tubular KT-joints subjected to axial loading at fire induced elevated temperatures. At first, a finite element (FE) model was developed and validated against the data available from experimental tests. Then, a set of 810 FE analyses were performed to study the influence of temperature and dimensionless geometrical parameters (β, γ, θ, and τ) on the ultimate strength and initial stiffness. The joints were analyzed under two types of axial loading and five different temperatures (20 ºC, 200 ºC, 400 ºC, 550 ºC, and 700 ºC). Results show that the ultimate strength and initial stiffness of KT-joints decrease considerably by increasing the temperature. In the joints having bigger values of the β, the temperature elevation leads to less reduction in ultimate strength; while in the joints with bigger values of the γ, the temperature elevation results in more reduction in ultimate strength. The influence of the θ on the ultimate strength is independent from the temperature. To our knowledge, there is no design formula available for determining the ultimate strength of KT-joints at elevated temperatures. Hence, after parametric study, two equations were developed through nonlinear regression, for calculating the ultimate strength of KT-joints at elevated temperatures.

Keywords: axial loads, fire condition, parametric formula, static strength, tubular KT-joint

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Authors: Babagana Mohammed, Fidelis Patrick Afangide

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This research investigated the possibility of using waste low-dense polyethylene and waste plastic bottles for the production of interlock pavement blocks. In many parts of the world, interlock pavement block is used widely as modern day solution to outdoor flooring applications and the blocks have different shapes, sizes and colours suiting the imagination of landscape architects. Using suitable and conventional mould having a 220 x 135 x 50 mm³ shape, the interlock blocks were produced. The material constituents of the produced blocks were waste low-dense polyethylene and waste plastic bottles mixed in varying, respective percentage-weight proportions of; 100%+0%, 75%+25%, 50%+50% and 25%+75%. The blocks were then tested for unconfined compressive strength and water absorption properties. The test results compared well with those of conventional concrete interlock blocks and the research demonstrates the possibility of value recovery from the waste streams which are currently dumped in open-spaces thereby affecting the environment.

Keywords: pavement blocks, polyethylene, plastic bottle, wastes, valorization

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Authors: Albert Gyamfi

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Cocoa plays critical role in the socio-economic development of Ghana. Meanwhile, smallholder farmers most of whom are illiterate dominate the industry. According to the cocoa-based agricultural knowledge and information system (AKIS) model knowledge is created and transferred to the industry between three key actors: cocoa researchers, extension experts, and cocoa farmers. Dwelling on the SECI model, the media richness theory (MRT), and the AKIS model, a conceptual model of web 2.0-based AKIS model (AKIS 2.0) is developed and used to assess the possible effects of social media usage for knowledge creation in the Ghanaian cocoa industry. A mixed method approach with a survey questionnaire was employed, and a second-order multi-group structural equation model (SEM) was used to analyze the data. The study concludes that the use of web 2.0 applications for knowledge creation would lead to sustainable interactions among the key knowledge actors for effective knowledge creation in the cocoa industry in Ghana.

Keywords: agriculture, cocoa, knowledge, media, web 2.0

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Authors: Marjan Golmaryami, Marzieh Behzadi

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Recent developments in stock exchange highlight the need for an efficient and accurate method that helps stockholders make better decision. Since stock markets have lots of fluctuations during the time and different effective parameters, it is difficult to make good decisions. The purpose of this study is to employ artificial neural network (ANN) which can deal with time series data and nonlinear relation among variables to forecast next day stock price. Unlike other evolutionary algorithms which were utilized in stock exchange prediction, we trained our proposed neural network with metaheuristic bat algorithm, with fast and powerful convergence and applied it in stock price prediction for the first time. In order to prove the performance of the proposed method, this research selected a 7 year dataset from Parsian Bank stocks and after imposing data preprocessing, used 3 types of ANN (back propagation-ANN, particle swarm optimization-ANN and bat-ANN) to predict the closed price of stocks. Afterwards, this study engaged MATLAB to simulate 3 types of ANN, with the scoring target of mean absolute percentage error (MAPE). The results may be adapted to other companies stocks too.

Keywords: artificial neural network (ANN), bat algorithm, particle swarm optimization algorithm (PSO), stock exchange

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Authors: Babanyara Y. Y., Ibrahim D. B., Garba T., Bogoro A. G., Abubakar, M. Y.

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Medical care is vital for our life, health, and well-being. However, the waste generated from medical activities can be hazardous, toxic, and even lethal because of their high potential for diseases transmission. The hazardous and toxic parts of waste from healthcare establishments comprising infectious, medical, and radioactive material as well as sharps constitute a grave risks to mankind and the environment, if these are not properly treated/disposed or are allowed to be mixed with other municipal waste. In Nigeria, practical information on this aspect is inadequate and research on the public health implications of poor management of medical wastes is few and limited in scope. Findings drawn from Literature particularly in the third world countries highlights financial problems, lack of awareness of risks involved in MWM, lack of appropriate legislation and lack of specialized MWM staff. The paper recommends how MWM practices can be improved in medical facilities.

Keywords: environmental pollution, infectious, management, medical waste, public health

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Authors: Reza Mohammadzadeh

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The major challenges in geotechnical engineering in underground spaces arise from uncertainties and different probabilities. The collection, collation, and collaboration of existing data to incorporate them in analysis and design for given prospect evaluation would be a reliable, practical problem solving method under uncertainty. Machine learning (ML) is a subfield of artificial intelligence in statistical science which applies different techniques (e.g., Regression, neural networks, support vector machines, decision trees, random forests, genetic programming, etc.) on data to automatically learn and improve from them without being explicitly programmed and make decisions and predictions. In this paper, a conceptual database schema of geotechnical risks in underground coal mining based on a cloud system architecture has been designed. A new approach of risk assessment using a three-dimensional risk matrix supported by the level of knowledge (LoK) has been proposed in this model. Subsequently, the model workflow methodology stages have been described. In order to train data and LoK models deployment, an ML platform has been implemented. IBM Watson Studio, as a leading data science tool and data-driven cloud integration ML platform, is employed in this study. As a Use case, a data set of geotechnical hazards and risk assessment in underground coal mining were prepared to demonstrate the performance of the model, and accordingly, the results have been outlined.

Keywords: data model, geotechnical risks, machine learning, underground coal mining

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Authors: Abbas Fazelinia

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Terrorism is not a new phenomenon to the world, yet it remains difficult to define and to counter. Countering terrorism requires several measures that must be taken at the same time. Counterterrorism strategies of most countries depend on military measures. However, those strategies should also focus on nonlethal measures, such as economic, political, and social measures. The psychological dimensions of terrorism must be understood, evaluated, and used in countering terrorism. This study suggests that psychological operations, as nonlethal military operations, can be used to influence individuals not to join terrorist organizations and to facilitate defections from terrorist organizations. However, in order to implement effective psychological operations, one has to have appropriate intelligence about terrorist organizations. Examining terrorist organizations help us to identify their vulnerabilities and obtain this intelligence. This article concludes that terrorists’ motivations, terrorist organizations’ radicalization, recruitment, and conversion processes, ideology, goals, strategies, and general structure form the intelligence requirement for psychological operations in counterterrorism. The methodology used in this article is a mixed method.

Keywords: psychological operations, terrorist, counterterrorism, terrorism

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Authors: Zaouche Mohammed, Amini Mohammed, Foughali Khaled, Hamissi Aicha, Aktouf Mohand Arezki, Boureghda Ilyes

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In this paper, we present a piloting law based on the adaptive differentiators via high order sliding mode controller, by using an aircraft in virtual simulated environment. To deal with the design of an autopilot controller, we propose a framework based on Software in the Loop (SIL) methodology and we use Microsoft^TM Flight Simulator (FS-2004) as the environment for plane simulation. The aircraft dynamic model is nonlinear, Multi-Input Multi-Output (MIMO) and tightly coupled. The nonlinearity resides in the dynamic equations and also in the aerodynamic coefficients' variability. In our case, two (02) aircrafts are used in the flight tests, the Zlin-142 and MQ-1 Predator. For both aircrafts and in a very low altitude flight, we send the piloting control inputs to the aircraft which has stalled due to a command disconnection. Then, we present the aircraft’s dynamic behavior analysis while reestablishing the command transmission. Finally, a comparative study between the two aircraft’s dynamic behaviors is presented.

Keywords: adaptive differentiators, second order sliding modes, dynamic adaptation of the gains, microsoft flight simulator, Zlin-142, MQ-1 predator

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Authors: Ishtiaque Qureshi, Erum Muzaffar

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This study aimed to analyze the causes of non-disclosure of intrafamilial childhood sexual abuse (IFCSA) among survivors studying in higher education institutions in Sindh, Pakistan. Employing a mixed-method approach, the research investigated the reasons behind non-disclosure. A quantitative survey conducted in higher education institutions identified IFCSA victims through purposive sampling, and the causes were assessed through in-depth interviews with 18 respondents. Subsequent analysis of the interview transcripts resulted in the categorization of respondents into three groups: (1) those fearing the consequences of revealing facts to their parents, (2) individuals unwilling to subject their parents to conflict with the perpetrator, and (3) those who could not disclose the abuse due to reasons not understood by them. Correlations among non-disclosing respondents were examined with respect to their socio-economic status, family structure, emotional availability of parents, and parenting style.

Keywords: intrafamilial childhood sexual abuse, non-disclosure, survivors of IFCSA, in-depth interviews

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Authors: B. Mahfoud, A. Bendjagloli

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The effect of an axial magnetic field on the flow produced by co-rotation of the top and bottom disks in a vertical cylindrical heated from below is numerically analyzed. The governing Navier-Stokes, energy, and potential equations are solved by using the finite-volume method. It was observed that the Reynolds number is increased, the axisymmetric basic state loses stability to circular patterns of axisymmetric vortices and spiral waves. In mixed convection case the axisymmetric mode disappears giving an asymmetric mode m=1. It was also found that the primary thresholds Recr corresponding to the modes m=1and 2, increase with increasing of the Hartmann number (Ha). Finally, stability diagrams have been established according to the numerical results of this investigation. These diagrams giving the evolution of the primary thresholds as a function of the Hartmann number for various values of the Richardson number.

Keywords: bifurcation, co-rotating end disks, magnetic field, stability diagrams, vortices

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Authors: Asifa Amara, Prachi Singh, Kanishka, Debargho Pathak, Akshat Kumar, Jayakumar Eravelly

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Today's generation is totally dependent on technology that uses data as its fuel. The present study is all about innovations and developments in data science and gives an idea about how efficiently to use the data provided. This study will help to understand the core concepts of data science. The concept of artificial intelligence was introduced by Alan Turing in which the main principle was to create an artificial system that can run independently of human-given programs and can function with the help of analyzing data to understand the requirements of the users. Data science comprises business understanding, analyzing data, ethical concerns, understanding programming languages, various fields and sources of data, skills, etc. The usage of data science has evolved over the years. In this review article, we have covered a part of data science, i.e., machine learning. Machine learning uses data science for its work. Machines learn through their experience, which helps them to do any work more efficiently. This article includes a comparative study image between human understanding and machine understanding, advantages, applications, and real-time examples of machine learning. Data science is an important game changer in the life of human beings. Since the advent of data science, we have found its benefits and how it leads to a better understanding of people, and how it cherishes individual needs. It has improved business strategies, services provided by them, forecasting, the ability to attend sustainable developments, etc. This study also focuses on a better understanding of data science which will help us to create a better world.

Keywords: data science, machine learning, data analytics, artificial intelligence

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Authors: Andriy Didenko, Zanin Kavazovic

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Engineering students often have certain difficulties in mastering major theoretical concepts in mathematical courses such as differential equations. Student projects were proposed to motivate students’ learning and can be used as a tool to promote students’ interest in the material. Authors propose a student project that includes the use of Microsoft Excel. This instructional tool is often overlooked by both educators and students. An integral component of the experimental part of such a project is the exploration of an interactive spreadsheet. The aim is to assist engineering students in better understanding of Euler’s method. This method is employed to numerically solve first order differential equations. At first, students are invited to select classic equations from a list presented in a form of a drop-down menu. For each of these equations, students can select and modify certain key parameters and observe the influence of initial condition on the solution. This will give students an insight into the behavior of the method in different configurations as solutions to equations are given in numerical and graphical forms. Further, students could also create their own equations by providing functions of their own choice and a variety of initial conditions. Moreover, they can visualize and explore the impact of the length of the time step on the convergence of a sequence of numerical solutions to the exact solution of the equation. As a final stage of the project, students are encouraged to develop their own spreadsheets for other numerical methods and other types of equations. Such projects promote students’ interest in mathematical applications and further improve their mathematical and programming skills.

Keywords: student project, Euler's method, spreadsheet, engineering education

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Authors: Ali Reza Sattarzadeh, Ronny J. Kutadinata, Pubudu N. Pathirana, Van Thanh Huynh

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Traffic congestion has become a severe worldwide problem, affecting everyday life, fuel consumption, time, and air pollution. The primary causes of these issues are inadequate transportation infrastructure, poor traffic signal management, and rising population. Traffic flow forecasting is one of the essential and effective methods in urban congestion and traffic management, which has attracted the attention of researchers. With the development of technology, undeniable progress has been achieved in existing methods. However, there is a possibility of improvement in the extraction of temporal and spatial features to determine the importance of traffic flow sequences and extraction features. In the proposed model, we implement the convolutional neural network (CNN) and long short-term memory (LSTM) deep learning models for mining nonlinear correlations and their effectiveness in increasing the accuracy of traffic flow prediction in the real dataset. According to the experiments, the results indicate that implementing Conv-LSTM networks increases the productivity and accuracy of deep learning models for traffic flow prediction.

Keywords: deep learning algorithms, intelligent transportation systems, spatiotemporal features, traffic flow prediction

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Authors: Navid Khayat

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Drained shear strength of saturated soils is fully understood. Shear strength of unsaturated soils is usually expressed in terms of soil suction. Evaluation of shear strength of compacted mixtures of sand–clay at optimum water content is main purpose of this research. To prepare the required samples, first clay and sand are mixed in 10, 30, 50, and 70 percent by dry weight and then compacted at the proper optimum water content according to the standard proctor test. The samples were sheared in direct shear machine. Stress –strain relationship of samples indicated a ductile behavior. Most of the samples showed a dilatancy behavior during the shear and the tendency for dilatancy increased with the increase in sand proportion. The results show that with the increase in percentage of sand a decrease in cohesion intercept c' for mixtures and an increase in the angle of internal friction Φ’is observed.

Keywords: clay, sand, drained shear strength, cohesion intercept

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Authors: Mustafa Kara, Yasemin Kilic, Bahattin Murat Demir, Ümit Ustaoglu, Cavit Unal

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This paper reports utilization of different kind of construction and demolition wastes (C&D) in the production of bricks at industrial scale. Plastered brick waste and tile wastes were collected from ISTAÇ Co. Compost and Recovery Plant, Istanbul, Turkey. Plastered brick waste and tile waste are mixed with brick clay in the proportion of 0-30% and fired at 900ºC. The physical and mechanical properties of the produced bricks were determined and evaluated according to IKIZLER Brick Company Production values, Brick Industry Association (BIA) and Turkish Standards (TS). The resulted showed that plastered brick waste and tile waste can be used to produce good quality brick for various engineering applications in construction and building. The replacement of brick clay by plastered brick waste and tile waste at the levels of 30% has good effects on the compressive strength of the bricks.

Keywords: commercial brick, construction and demolition waste, manufacturing, recycling

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Authors: Saemee Jun, Dong-Hyeon Shin, Tae-Sang Ahn, Hyung-Joon Kim

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Building loss estimation methodologies which have been advanced considerably in recent decades are usually used to estimate socio and economic impacts resulting from seismic structural damage. In accordance with these methods, this paper presents the evaluation of an annual loss probability of a reinforced concrete moment resisting frame designed according to Korean Building Code. The annual loss probability is defined by (1) a fragility curve obtained from a capacity spectrum method which is similar to a method adopted from HAZUS, and (2) a seismic hazard curve derived from annual frequencies of exceedance per peak ground acceleration. Seismic fragilities are computed to calculate the annual loss probability of a certain structure using functions depending on structural capacity, seismic demand, structural response and the probability of exceeding damage state thresholds. This study carried out a nonlinear static analysis to obtain the capacity of a RC moment resisting frame selected as a prototype building. The analysis results show that the probability of being extensive structural damage in the prototype building is expected to 0.004% in a year.

Keywords: expected annual loss, loss estimation, RC structure, fragility analysis

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Authors: Linyu Wang, Jiahui Ma, Jianhong Xiang, Hanyu Jiang

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For the pilot design of the sparse channel estimation model in Multiple Input Multiple Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems, the observation matrix constructed according to the matrix cross-correlation criterion, total correlation criterion and other optimization criteria are not optimal, resulting in inaccurate channel estimation and high bit error rate at the receiver. This paper proposes a pilot design method combining high-power sum and high-power variance criteria, which can more accurately estimate the channel. First, the pilot insertion position is designed according to the high-power variance criterion under the condition of equal power. Then, according to the high power sum criterion, the pilot power allocation is converted into a cone programming problem, and the power allocation is carried out. Finally, the optimal pilot is determined by calculating the weighted sum of the high power sum and the high power variance. Compared with the traditional pilot frequency, under the same conditions, the constructed MIMO-OFDM system uses the optimal pilot frequency for channel estimation, and the communication bit error rate performance obtains a gain of 6~7dB.

Keywords: MIMO-OFDM, pilot optimization, compressed sensing, channel estimation

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Authors: Guangyuan Zhao, Nan Huang, Xuesong Han, Xu Huang

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In order to solve the problem of sample dilution in the traditional particle filter algorithm and achieve accurate state estimation in a nonlinear system, a particle filter method based on an improved artificial bee colony (ABC) algorithm was proposed. The algorithm simulated the process of bee foraging and optimization and made the high likelihood region of the backward probability of particles moving to improve the rationality of particle distribution. The opposition-based learning (OBL) strategy is introduced to optimize the initial population of the artificial bee colony algorithm. The convergence factor is introduced into the neighborhood search strategy to limit the search range and improve the convergence speed. Finally, the crossover and mutation operations of the genetic algorithm are introduced into the search mechanism of the following bee, which makes the algorithm jump out of the local extreme value quickly and continue to search the global extreme value to improve its optimization ability. The simulation results show that the improved method can improve the estimation accuracy of particle filters, ensure the diversity of particles, and improve the rationality of particle distribution.

Keywords: particle filter, impoverishment, state estimation, artificial bee colony algorithm

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Authors: Sperisa Distantina, Rieke Ulfha Noviyanti, Sri Sutriyani, Fadilah Fadilah, Mujtahid Kaavessina

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In this research, carrageenan extracted from seaweed Eucheuma cottonii was mixed with polyvinyl alcohol (PVA) and then crosslinked using glutaraldehyde (GA). The obtained hydrogel films were applied to control the drug release rate of paracetamol. The aim of this research was to develop a mathematical model that can be used to describe the mass transfer rate of paracetamol from the hydrogel film into buffer solution. The effect of weight ratio carrageenan-PVA (5: 0, 1: 0.5, 1: 1, 1: 2, 0: 5) on the parameters of the mathematical model was investigated also. Based on the experimental data, the proposed mathematical model could describe the mass transfer rate of paracetamol. The weight ratio of carrageenan-PVA greatly affected the amount of paracetamol absorbed in the hydrogel film and the mass transfer rate of paracetamol.

Keywords: carrageenan-PVA, crosslinking, glutaraldehyde, hydrogel, paracetamol, mass transfer

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Authors: Yemalin D. Agossou, Andre Lecomte, Remi Boissiere, Edmond C. Adjovi, Abdelouahab Khelil

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This paper presents a mixed design trial of structural concretes with laterites from Benin. These materials are often the only granular resources readily available in many tropical regions. In the first step, concretes were designed with raw laterites, but the performances obtained were rather disappointing in spite of high cement dosages. A detailed physical characterization of these materials then showed that they contained a significant proportion of fine clays and that the coarsest fraction (gravel) contained a variety of facies, some of which were not very dense or indurated. Washing these laterites, and even the elimination of the most friable grains of the gravel fraction, made it possible to obtain concretes with satisfactory properties in terms of workability, density and mechanical strength. However, they were found to be slightly less stiff than concretes made with more traditional aggregates. It is, therefore, possible to obtain structural concretes with only laterites and cement but at the cost of eliminating some of their granular constituents.

Keywords: laterites, aggregates, concretes, mix design, mechanical properties

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Authors: Flávia M. Oliveira, Marcos V. Rodrigues, Mônica L. Aguiar

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Synthetic fibers are widely used in gas filtration. Previous attempts to optimize the filtration process have employed mixed fibers as the filter medium in gas-solid separation. Some of the materials most frequently used this purpose are composed of polyester, polypropylene, and glass fibers. In order to improve the retention of cement particles in bag filters, the present study investigates the use of synthetic glass fiber filters and polypropylene fiber for particle filtration, with electrostatic discharge of 0 to -2 kV in cement particles. The filtration curves obtained showed that charging increased the particle collection efficiency and lowered the pressure drop. Particle diameter had a direct influence on the formation of the dust cake, and the application of electrostatic discharge to the particles resulted in the retention of more particles, hence increasing the lifetime of fabric filters.

Keywords: glass fiber filter, particle, electrostatic discharge, cement

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Authors: A. Sivakumar, S. S. Darun Prakash, P. Navaneethakrishnan

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In and around Erode District, it is estimated that more than 1250 chemical and allied textile processing fabric industries are affected, partially closed and shut off for various reasons such as poor management, poor supplier performance, lack of planning for productivity, fluctuation of output, poor investment, waste analysis, labor problems, capital/labor ratio, accumulation of stocks, poor maintenance of resources, deficiencies in the quality of fabric, low capacity utilization, age of plant and equipment, high investment and input but low throughput, poor research and development, lack of energy, workers’ fear of loss of jobs, work force mix and work ethic. The main objective of this work is to analyze the existing conditions in textile fabric sector, validate the break even of Total Productivity (TP), analyze, design and implement fuzzy sets and mathematical programming for improvement of productivity and quality dimensions in the fabric processing industry. It needs to be compatible with the reality of textile and fabric processing industries. The highly risk events from productivity and quality dimension were found by fuzzy systems and results are wrapped up among the textile fabric processing industry.

Keywords: break even point, fuzzy crisp data, fuzzy sets, productivity, productivity cycle, total productive maintenance

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Authors: A. Apostolopoulou, D. Sygkridou, A. N. Kalarakis, E. Stathatos

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Mesoscopic perovskite solar cells (mp-PSCs) with mesoporous bilayer were fabricated under ambient conditions. The bilayer was formed by capping the mesoporous TiO₂ layer with a layer of In₂O₃. CH₃NH₃I_3-xCl_x mixed halide perovskite was prepared through the one-step method and was used as the light absorber. The mp-PSCs with the composite TiO₂/In₂O₃ mesoporous layer exhibited optimized electrical parameters, compared with the PSCs that employed only a TiO₂ mesoporous layer, with a current density of 23.86 mA/cm², open circuit voltage of 0.863 V, fill factor of 0.6 and a power conversion efficiency of 11.2%. These results indicate that the formation of a proper semiconductor capping layer over the basic TiO₂ mesoporous layer can facilitate the electron transfer, suppress the recombination and subsequently lead to higher charge collection efficiency.

Keywords: ambient conditions, high efficiency solar cells, mesoscopic perovskite solar cells, TiO₂ / In₂O₃ bilayer

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Authors: Gilbert Makanda, Roelf Sypkens

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A mathematical model for knowledge acquisition in teaching and learning is proposed. In this study we adopt the mathematical model that is normally used for disease modelling into teaching and learning. We derive mathematical conditions which facilitate knowledge acquisition. This study compares the effects of dropping out of the course at early stages with later stages of learning. The study also investigates effect of individual interaction and learning from other sources to facilitate learning. The study fits actual data to a general mathematical model using Matlab ODE45 and lsqnonlin to obtain a unique mathematical model that can be used to predict knowledge acquisition. The data used in this study was obtained from the tutorial test results for mathematics 2 students from the Central University of Technology, Free State, South Africa in the department of Mathematical and Physical Sciences. The study confirms already known results that increasing dropout rates and forgetting taught concepts reduce the population of knowledgeable students. Increasing teaching contacts and access to other learning materials facilitate knowledge acquisition. The effect of increasing dropout rates is more enhanced in the later stages of learning than earlier stages. The study opens up a new direction in further investigations in teaching and learning using differential equations.

Keywords: differential equations, knowledge acquisition, least squares nonlinear, dynamical systems

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Authors: Sergey Kopysov, Nikita Nedozhogin, Leonid Tonkov

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The article presents a parallel iterative solver for large sparse linear systems which can be used on a heterogeneous platform. Traditionally, the problem of solving linear systems does not scale well on multi-CPU/multi-GPUs clusters. For example, most of the attempts to implement the classical conjugate gradient method were at best counted in the same amount of time as the problem was enlarged. The paper proposes the pipelined variant of the conjugate gradient method (PCG), a formulation that is potentially better suited for hybrid CPU/GPU computing since it requires only one synchronization point per one iteration instead of two for standard CG. The standard and pipelined CG methods need the vector entries generated by the current GPU and other GPUs for matrix-vector products. So the communication between GPUs becomes a major performance bottleneck on multi GPU cluster. The article presents an approach to minimize the communications between parallel parts of algorithms. Additionally, computation and communication can be overlapped to reduce the impact of data exchange. Using the pipelined version of the CG method with one synchronization point, the possibility of asynchronous calculations and communications, load balancing between the CPU and GPU for solving the large linear systems allows for scalability. The algorithm is implemented with the combined use of technologies: MPI, OpenMP, and CUDA. We show that almost optimum speed up on 8-CPU/2GPU may be reached (relatively to a one GPU execution). The parallelized solver achieves a speedup of up to 5.49 times on 16 NVIDIA Tesla GPUs, as compared to one GPU.

Keywords: conjugate gradient, GPU, parallel programming, pipelined algorithm

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Authors: Abdulsamee Halahla, Emad Allout

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The purpose of this research is to study the behavior of exterior beam-column joints (BCJs) strengthened with ultra-high performance concrete (UHPC), in terms of the shear strength and maximum displacement using pushover analysis at the tip of the beam. A finite element (F.E) analysis was performed to study three main parameters – the level of the axial load in the column (N), the beam shear reinforcement (Av/s)B, and the effect of using UHPC. The normal concrete at the studied joint region was replaced by UHPC. The model was verified by using experimental results taken from the literature. The results showed that the UHPC contributed to the transference of the plastic hinge from the joint to the beam-column interface. In addition, the strength of the UHPC-strengthened joints was enhanced dramatically from 8% to 38% for the joints subjected to 12.8MPa and zero axial loads, respectively. Moreover, the UHPC contributed in improving the maximum deflection. This improvement amounted to 1% and 176% for the joints subjected to zero and 12.8MPa axial load, respectively.

Keywords: ultra high performance concrete, ductility, reinforced concrete joints, finite element modeling, nonlinear behavior; pushover analysis

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Authors: Osungwu Emeka

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Until recently, Port Harcourt was known as the “Garden City of Nigeria” because of its neatness and the overwhelming presence of vegetation all over the metropolis. But today, the presence of piles of refuse dotting the entire city may have turned Port Harcourt into a “Garbage City”. Indiscriminate dumping of industrial, commercial and household wastes such as food waste, paper, polythene, textiles, scrap metals, glasses, wood, plastic, etc. at street corners and gutters, is still very common. The waste management problem in the state affects the citizens both directly and indirectly. The dumping of waste along the roadside obstructs traffic and, after mixing with rain water may sip underground with the possibility of the leachate contaminating the groundwater. The basic solid waste management processes of collection, transportation, segregation and final disposal appear to be very inefficient. This study was undertaken to assess waste utilization using metal waste scavengers. Highlighting their activities as a part of the informal sector of the solid waste management system with a view to identifying their challenges, prospects and possible contributions to the solid waste management system in the Port Harcourt metropolis. Therefore, the aim was to understand and assess scavenging as a system of solid waste management in Port Harcourt and to identify the main bottlenecks to its efficiency and the way forward. This study targeted people who engage in scavenging metal scraps across 5 major waste dump sites across Port Harcourt. To achieve this, a mixed method study was conducted to provide both experiential evidence on this waste utilization method using a qualitative study and a survey to collect numeric evidence on this subject. The findings from the qualitative string of this study provided insight on scavenging as a waste utilization activity and how their activities can reduce the gross waste generated and collected from the subject areas. It further showed the nature and characteristics of scavengers in the waste recycling system as a means of achieving the millennium development goals towards poverty alleviation, job creation and the development of a sustainable, cleaner environment. The study showed that in Port Harcourt, the waste management practice involves the collection, transportation and disposal of waste by refuse contractors using cart pushers and disposal vehicles at designated dumpsites where the scavengers salvage metal scraps for recycling and reuse. This study further indicates that there is a great demand for metal waste materials/products that are clearly identified as genuinely sustainable, even though they may be perceived as waste. The market for these waste materials shall promote entrepreneurship as a profitable venture for waste recovery and recycling in Port Harcourt. Therefore, the benefit of resource recovery and recycling as a means of the solid waste management system will enhance waste to wealth that will reduce pollution, create job opportunities thereby alleviate poverty.

Keywords: scavengers, metal waste, waste-to-wealth, recycle, Port Harcourt, Nigeria, waste reduction, garden city, waste

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Authors: Isaac Owusu Asante, Yushi Jiang, Hailin Tao

Abstract:

Live streaming marketing, the new electronic commerce element, became an optional marketing channel following the COVID-19 pandemic. Many sellers have leveraged the features presented by live streaming to increase sales. Studies on live streaming have focused on gaming and consumers’ loyalty to brands through live streaming, using interview questionnaires. This study, however, was conducted to measure real-time observable interactions between consumers and sellers. Based on the affordance theory, this study conceptualized constructs representing the interactive features and examined how they drive consumers’ purchase willingness during live streaming sessions using 1238 datasets from Amazon Live, following the manual observation of transaction records. Using structural equation modeling, the ordinary least square regression suggests that live viewers, new followers, live chats, and likes positively affect purchase willingness. The Sobel and Monte Carlo tests show that new followers, live chats, and likes significantly mediate the relationship between live viewers and purchase willingness. The study introduces a new way of measuring interactions in live streaming commerce and proposes a way to manually gather data on consumer behaviors in live streaming platforms when the application programming interface (API) of such platforms does not support data mining algorithms.

Keywords: livestreaming marketing, live chats, live viewers, likes, new followers, purchase willingness

Procedia PDF Downloads 81

Authors: Rafal Sochaczewski, Grzegorz Baranski, Adam Majczak

Abstract:

This paper presents the bench research results on a CNG injector at steady state. The quantities measured included voltage and current in a solenoid, pressure of gas behind an injector and injector’s flow rate. Accordingly, injector’s operation parameters were determined according to needle’s lift and injection pressure. The discrepancies between the theoretical (electric) and actual time of injection were defined to specify injector’s opening and closing lag times and the uniqueness of these values in successive cycles of gas injection. It has been demonstrated that needle’s lift has got a stronger impact on injector’s operating parameters than injection pressure. With increasing injection pressure, the force increases and closes an injection valve, which adversely affects uniqueness of injector’s operation. The paper also describes the concept of an injector dedicated to direct CNG injection into a combustion chamber in a dual-fuel engine. The injector’s design enables us to replace 80% of diesel fuel in a dual-fuel engine with a maximum power of 85 kW. Minimum injection pressure is 1,4 MPa then. Simultaneously, injector’s characteristics for varied needle’s lifts and injector’s nonlinear operating points were developed. Acknowledgement: This work has been financed by the Polish National Centre for Research and Development, under Grant Agreement No. PBS1/A6/4/2012.

Keywords: CNG injector, diesel engine, direct injection, dual fuel

Procedia PDF Downloads 276