Search results for: external convective heat transfer coefficients

Authors: K. B. Ghazaryan, R. A. Ghazaryan

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Based on the constitutive model and anti-plane equations of anisotropic elastic body of monoclinic symmetry we consider the problem of shear wave propagation in multi-layered disordered composite structure with point defect. Using transfer matrix method the analytic expression is obtained providing solutions of shear Floquet wave propagation in periodic disordered anisotropic structure. The usefulness of the obtained analytical expression was discussed also in reflection and refraction problems from multi-layered reflector as well as in vibration problem of multi-layered waveguides. Numerical results are presented highlighting the effects arising in disordered periodic structure due to defects of multi-layered structure.

Keywords: shear elastic waves, monoclinic anisotropic media, periodic structure, disordered multilayer laminae, multi-layered waveguide

Procedia PDF Downloads 408

Authors: Sunday Ofum Ogon

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The 1648 Westphalia Conference in Europe ushered in the state as the only legal entity with powers to engage in interstate relations on matters that bothers on the development need of her citizens. This epochal entry of the state reshaped global relations with the curtailment of the powers of individual and groups in external relations as the state became the only entity that acted on behalf of any individual or non-state actors like NGOs residing within the parameters of such a country. Thus, the paper interrogated the extent at which the state determines her Politico-Economic relations with regards to development and growth within the state. To achieve these objectives, the paper relied on documentary evidences wherein the qualitative descriptive method was used for data collection and analysis. The paper exploited the facilities of the Rentier State theory as a guide to the study. It was revealed at the end of the study that the 21st century global economic relations is largely determine by international organizations as exemplified by the World Bank and the International Monitory Fund (IMF) where their activities in the continent has undermined state sovereignty. Hence the paper recommended amongst others that states should look inward for development strategies rather than relying on handout from supra-national organizations which has infringe on their sovereignty.

Keywords: State , Global , Rentier state, Twenty-First Century

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Authors: Min Ye Koo, Ji Ho Ahn, Byung Il You, Gyo Woo Lee

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Everything that is attached to the outside of the vehicle to improve the driving performance of the vehicle by changing the flow characteristics of the surrounding air or to pursue the external personality is called a tuning part. Typical tuning components include front or rear air dam, also known as spoilers, splitter, and side air dam. Particularly, the front air dam prevents the airflow flowing into the lower portion of the vehicle and increases the amount of air flow to the side and front of the vehicle body, thereby reducing lift force generation that lifts the vehicle body, and thus, improving the steering and driving performance of the vehicle. The purpose of this study was to investigate the role of anterior air dam in the flow around a sedan passenger car using computational fluid dynamics. The effects of flow velocity, trajectory of fluid particles on static pressure distribution and pressure distribution on body surface were investigated by varying flow velocity and size of air dam. As a result, it has been confirmed that the front air dam improves the flow characteristics, thereby reducing the generation of lift force of the vehicle, so it helps in steering and driving characteristics.

Keywords: numerical study, air dam, flow field, pressure distribution

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Authors: Seyed Mahdi Jameii

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Underwater wireless sensor networks have been attracting the interest of many ‎researchers lately, and the past three decades have beheld the rapid progress of ‎underwater acoustic communication. One of the major problems in underwater wireless ‎sensor networks is how to transfer data from the moving node to the base stations and ‎choose the optimized route for data transmission. Secure routing in underwater ‎wireless sensor network (UWCNs) is necessary for packet delivery. Some routing ‎protocols are proposed for underwater wireless sensor networks. However, a few ‎researches have been done on secure routing in underwater sensor networks. In this ‎article, a secure routing protocol is provided to resist against wormhole and sybil ‎attacks. The results indicated acceptable performance in terms of increasing the packet ‎delivery ratio with regards to the attacks, increasing network lifetime by creating ‎balance in the network energy consumption, high detection rates against the attacks, ‎and low-end to end delay.‎

Keywords: attacks, routing, security, underwater wireless sensor networks

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Authors: Jian-Xiu Wan, Yao Yin

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In complex terrain and poor geological conditions areas, Railway, highway and other transportation constructions are still strongly developing. However, various geological disasters happened such as landslide, rock heap and so on. According to the results of geological investigation, the form of skirt (trapezoidal), semicircle and triangle rock heaps are mainly due to complex internal force and external force, in a certain extent, which is related to the terrain, the nature of the rock mass, the supply area and the surface shape of rock heap. Combined with the above factors, discrete element numerical simulation of rock mass is established under different terrain conditions based on 3DEC, and accelerated formation process of rock heap under seismic action is simulated. The fragmentation structure supply area is calculated, in which the most dangerous area is located. At the same time, the formation mechanism and development process are studied in different terrain conditions, and the structure of rock heap is judged by section, which can provide a strong theoretical and technical support for the prevention and control of geological disasters.

Keywords: 3DEC, fragmentation structure, rock heap, slope, seismic action

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Authors: N. Bourayou, A. -H. Meniai, A. Gouaoura

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The presence of salt can either raise or lower the distribution coefficient of a solute acetic acid in liquid- liquid equilibria. The coefficient of solute is defined as the ratio of the composition of solute in solvent rich phase to the composition of solute in diluents (water) rich phase. The phenomena are known as salting–out or salting-in, respectively. The effect of monovalent salt, sodium chloride and the bivalent salt, sodium sulfate on the distribution of acetic acid between 1-butanol and water at 298.15K were experimentally shown to be effective in modifying the liquid-liquid equilibrium of water/acetic acid/1-butanol system in favour of the solvent extraction of acetic acid from an aqueous solution with 1-butanol, particularly at high salt concentrations of both salts. All the two salts studied are found to have to salt out effect for acetic acid in varying degrees. The experimentally measured data were well correlated by Eisen-Joffe equation. NRTL model for solvent mixtures containing salts was able to provide good correlation of the present liquid-liquid equilibrium data. Using the regressed salt concentration coefficients for the salt-solvent interaction parameters and the solvent-solvent interaction parameters obtained from the same system without salt. The calculated phase equilibrium was in a quite good agreement with the experimental data, showing the ability of NRTL model to correlate salt effect on the liquid-liquid equilibrium.

Keywords: activity coefficient, Eisen-Joffe, NRTL model, sodium chloride

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Authors: Naim Karasekreter, Ugur Fidan, Fatih Basciftci

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Wireless sensor networks are networks in which more than one sensor node is organized among themselves. The working principle is based on the transfer of the sensed data over the other nodes in the network to the central station. Wireless sensor networks concentrate on routing algorithms, energy efficiency and clustering algorithms. In the clustering method, the nodes in the network are divided into clusters using different parameters and the most suitable cluster head is selected from among them. The data to be sent to the center is sent per cluster, and the cluster head is transmitted to the center. With this method, the network traffic is reduced and the energy efficiency of the nodes is increased. In this study, clustering algorithms were examined in terms of clustering performances and cluster head selection characteristics to try to identify weak and strong sides. This work is supported by the Project 17.Kariyer.123 of Afyon Kocatepe University BAP Commission.

Keywords: wireless sensor networks (WSN), clustering algorithm, cluster head, clustering

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Authors: Wei Feilong

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In this study, an local invariant generalized Houghtransform (LI-GHT) method is proposed for integrated circuit (IC) visual positioning. The original generalized Hough transform (GHT) is robust to external noise; however, it is not suitable for visual positioning of IC chips due to the four-dimensionality (4D) of parameter space which leads to the substantial storage requirement and high computational complexity. The proposed LI-GHT method can reduce the dimensionality of parameter space to 2D thanks to the rotational invariance of local invariant geometric feature and it can estimate the accuracy position and rotation angle of IC chips in real-time under noise and blur influence. The experiment results show that the proposed LI-GHT can estimate position and rotation angle of IC chips with high accuracy and fast speed. The proposed LI-GHT algorithm was implemented in IC visual positioning system of radio frequency identification (RFID) packaging equipment.

Keywords: Integrated Circuit Visual Positioning, Generalized Hough Transform, Local invariant Generalized Hough Transform, ICpacking equipment

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Authors: I. K. Sharma

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Over the years world over system are being developed by research labs continuously monitor under water parameters in the coastal waters of sea such as conductivity, salinity, pressure, temperature, chlorophyll and biological blooms at different levels of water column. The research institutions have developed profilers which are launched by ship connected through cable, glider type profilers following underwater trajectory, buoy any driven profilers, wire guided profilers etc. In all these years, the effect was to design autonomous profilers with no cable quality connection, simple operation and on line date transfer in terms accuracy, repeatability, reliability and consistency. Hence for the Ministry of Communication and Information Technology, India sponsored research project to National Institute of Oceanography, GOA, India to design and develop autonomous vertical profilers, it has taken system and AVP has been successfully developed and tested.

Keywords: oceanography, water column, autonomous profiler, buoyancy

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Authors: Christian Luarca

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The study aims to define the efficiency of e-Trainings by the use of cloud platform as part of the onboarding process for IT support engineers. Traditional lecture based trainings involves human resource to guide and assist new hires as part of onboarding which takes time and effort. The use of electronic medium as a platform for training provides a two-way basic communication that can be done in a repetitive manner. The study focuses on determining the most efficient manner of learning the basic knowledge on IT support in the shortest time possible. This was determined by conducting the same set of knowledge transfer categories in two different approaches, one being the e-Training and the other using the traditional method. Performance assessment will be done by the use of Service Tracker Assessment (STA) Tool and Service Manager. Data gathered from this ongoing study will promote the utilization of e-Trainings in the IT onboarding process.

Keywords: cloud platform, e-Training, efficiency, onboarding

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Authors: Azeddine Ghodbane, David Bensoussan, Maher Hammami

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An innovative approach for controlling unstable and invertible systems has demonstrated superior performance compared to conventional controllers. It has been successfully applied to a levitation system and drone control. Simulations have yielded satisfactory performances when applied to a satellite antenna controller. This design method, based on sensitivity analysis, has also been extended to handle multivariable unstable and invertible systems that exhibit dominant diagonal characteristics at high frequencies, enabling decentralized control. Furthermore, this control method has been expanded to the realm of adaptive control. In this study, we introduce an alternative adaptive architecture that enhances both time and frequency performance, helpfully mitigating the effects of disturbances from the input plant and external disturbances affecting the output. To facilitate superior performance in both the time and frequency domains, we have developed user-friendly interactive design methods using the GeoGebra platform.

Keywords: control theory, decentralized control, sensitivity theory, input-output stability theory, robust multivariable feedback control design

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Authors: Meriam Khelifa

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In recent years, many studies have focused on the harvesting of the vibrations energy to produce electrical energy using contact separation (CS) triboelectric nanogenerators (TENG). The simplest design for a TENG consists of a capacitor comprising a single moving electrode. The conversion efficiency of vibration energy into electrical energy can, in principle, reach 100%. But to actually achieve this objective, it is necessary to optimize the parameters of the TENG, such as the dielectric constant and the thickness of the insulator, the load resistance, etc. In particular, the use of a switch which is actioned at optimal times within the TENG cycle is essential. Using numerical modeling and experimental design, we applied a methodology to find the TENG parameters which optimize the energy transfer efficiency (ETE) to almost 100% for any vibration frequency and amplitude. The rather simple design of a TENG is promising as an environment friendly device. It opens the doors for harvesting acoustic vibrations from the environment and to design effective protection against environmental noise.

Keywords: vibrations, CS TENG, efficiency, design of experiments

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Authors: Vladimir Messerle, Alexandr Ustimenko, Oleg Lavrichshev

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This work presents plasma technology for solid fuel ignition and combustion. Plasma activation promotes more effective and environmentally friendly low-rank coal ignition and combustion. To realise this technology at coal fired power plants plasma-fuel systems (PFS) were developed. PFS improve efficiency of power coals combustion and decrease harmful emission. PFS is pulverized coal burner equipped with arc plasma torch. Plasma torch is the main element of the PFS. Plasma forming gas is air. It is blown through the electrodes forming plasma flame. Temperature of this flame is varied from 5000 to 6000 K. Plasma torch power is varied from 100 to 350 kW and geometrical sizes are the following: the height is 0.4-0.5 m and diameter is 0.2-0.25 m. The base of the PFS technology is plasma thermochemical preparation of coal for burning. It consists of heating of the pulverized coal and air mixture by arc plasma up to temperature of coal volatiles release and char carbon partial gasification. In the PFS coal-air mixture is deficient in oxygen and carbon is oxidised mainly to carbon monoxide. As a result, at the PFS exit a highly reactive mixture is formed of combustible gases and partially burned char particles, together with products of combustion, while the temperature of the gaseous mixture is around 1300 K. Further mixing with the air promotes intensive ignition and complete combustion of the prepared fuel. PFS have been tested for boilers start up and pulverized coal flame stabilization in different countries at power boilers of 75 to 950 t/h steam productivity. They were equipped with different types of pulverized coal burners (direct flow, muffle and swirl burners). At PFS testing power coals of all ranks (lignite, bituminous, anthracite and their mixtures) were incinerated. Volatile content of them was from 4 to 50%, ash varied from 15 to 48% and heat of combustion was from 1600 to 6000 kcal/kg. To show the advantages of the plasma technology before conventional technologies of coal combustion numerical investigation of plasma ignition, gasification and thermochemical preparation of a pulverized coal for incineration in an experimental furnace with heat capacity of 3 MW was fulfilled. Two computer-codes were used for the research. The computer simulation experiments were conducted for low-rank bituminous coal of 44% ash content. The boiler operation has been studied at the conventional mode of combustion and with arc plasma activation of coal combustion. The experiments and computer simulation showed ecological efficiency of the plasma technology. When a plasma torch operates in the regime of plasma stabilization of pulverized coal flame, NOX emission is reduced twice and amount of unburned carbon is reduced four times. Acknowledgement: This work was supported by Ministry of Education and Science of the Republic of Kazakhstan and Ministry of Education and Science of the Russian Federation (Agreement on grant No. 14.613.21.0005, project RFMEFI61314X0005).

Keywords: coal, ignition, plasma-fuel system, plasma torch, thermal power plant

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Authors: Arnold S. Freitas Neto, Rodrigo E. Coelho, Erick S. Mendonça

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This study aimed to obtain an alloy of Iron and Aluminum in the proportion of 50% of atomicity for each constituent. Alloys were obtained by processing recycled aluminum and chips of 1200 series carbon steel in a high-energy mill. For the experiment, raw materials were processed thorough high energy milling before mixing the substances. Subsequently, the mixture of 1200 series carbon steel and Aluminum powder was carried out a milling process. Thereafter, hot compression was performed in a closed die in order to obtain the samples. The pieces underwent heat treatments, sintering and aging. Lastly, the composition and the mechanical properties of their hardness were analyzed. In this paper, results are compared with previous studies, which used iron powder of high purity instead of Carbon steel in the composition.

Keywords: Fe-Al alloys, high energy milling, metallography characterization, powder metallurgy

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Authors: Vanitha Dapparabail

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Dowry is a system attached to Indian marriage system, it is practice of exchanging the goods and articles in a majority of Indian weddings. Although its practice became illegal in 1961, dowry flourishes among all social classes. Families of the bride and groom negotiate transfer of assets to the groom and his family in exchange for marrying the bride, often within the context of an arranged marriage. Dissatisfaction with the amount of dowry may result in abuse of the bride. In extreme cases “dowry deaths” or the murder of the bride by her husband and his family take place. This article conducts a feminist psychological analysis of the dowry phenomenon, its link to domestic violence against women, and the role of the perpetrators. Existing and new explanations of the dowry system and its ramifications are explored. Psychologically dowry system is greater mental stress for the Indian women and it is a really a part of gender discrimination. This part of the study can explore the amount of gender discrimination in Indian society.

Keywords: Dowry system, violence, gender discrimination, India

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Authors: Hongjian Jia

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A finite-length cylindrical shell with a spherical cap is a typical engineering approximation model of actual underwater targets. The research on the omni-directional acoustic scattering characteristics of this target model can provide a favorable basis for the detection and identification of actual underwater targets. The elastic resonance characteristics of the target are the results of the comprehensive effect of the target length, shell-thickness ratio and materials. Under the conditions of different materials and geometric dimensions, the coincidence resonance characteristics of the target have obvious differences. Aiming at this problem, this paper obtains the omni-directional acoustic scattering field of the underwater hemispherical cylindrical shell by numerical calculation and studies the influence of target geometric parameters (length, shell-thickness ratio) and material parameters on the coincidence resonance characteristics of the target in turn. The study found that the formant interval is not a stable value and changes with the incident angle. Among them, the formant interval is less affected by the target length and shell-thickness ratio and is significantly affected by the material properties, which is an effective feature for classifying and identifying targets of different materials. The quadratic polynomial is utilized to fully fit the change relationship between the formant interval and the angle. The results show that the three fitting coefficients of the stainless steel and aluminum targets are significantly different, which can be used as an effective feature parameter to characterize the target materials.

Keywords: hemispherical cylindrical shell;, fine echo characteristics;, geometric and material parameters;, formant interval

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Authors: Nidal H. Abu-Zahra, Aruna P. Wanninayake

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Copper Oxide (CuO) is a p-type semiconductor with a band gap energy of 1.5 eV, this is close to the ideal energy gap of 1.4 eV required for solar cells to allow good solar spectral absorption. The inherent electrical characteristics of CuO nano particles make them attractive candidates for improving the performance of polymer solar cells when incorporated into the active polymer layer. The UV-visible absorption spectra and external quantum efficiency of P3HT/PC70BM solar cells containing different weight percentages of CuO nano particles showed a clear enhancement in the photo absorption of the active layer, this increased the power conversion efficiency of the solar cells by 24% in comparison to the reference cell. The short circuit current of the reference cell was found to be 5.234 mA/cm2 and it seemed to increase to 6.484 mA/cm2 in cells containing 0.6 mg of CuO NPs; in addition the fill factor increased from 61.15% to 68.0%, showing an enhancement of 11.2%. These observations suggest that the optimum concentration of CuO nano particles was 0.6 mg in the active layer. These significant findings can be applied to design high-efficiency polymer solar cells containing inorganic nano particles.

Keywords: copper oxide nanoparticle, UV-visible spectroscopy, polymer solar cells, P3HT/PCBM

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Authors: Nazia Mustafa, Aneela Maqsood

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Pediatric Quality of Life Inventory is the most widely used instrument for assessing children and adolescent health-related quality of life and has shown excellent markers of reliability and validity. The current study was carried out with the objectives of translation and cross-language validation along with the determination of factor Structure and psychometric properties of the Urdu version. It was administered on 154 Primary School Children with age range 10 to12 years (M= 10.86, S.D = 0.62); including boys (n=92) and girls (n = 62). The sample was recruited from two randomly selected schools from the Rawalpindi district of Pakistan. Results of the pilot phase revealed that the instrument had good reliability (Urdu Version α = 0.798; English Version α = 0.795) as well as test-retest correlation coefficients over a period of 15 days (r = 0.85). Exploratory factor analysis (EFA) resulted in three factorial structures; Social/School Functioning (k = 8), Psychological Functioning (k = 7) and Physical Functioning (k = 6) considered suitable for our sample instead of four factors. Bartlett's test of sphericity showed inter-correlation between variables. However, factor loadings for items 22 and 23 of the School Functioning subscale were problematic. The model was fit to the data after their removal with Cronbach’s Alpha Reliability coefficient of the scale (k = 21) as 0.87 and for subscales as 0.75, 0.77 and 0.73 for Social/School Scale, Psychological subscale and Physical subscale, respectively. These results supported the feasibility and reliability of the Urdu version of the Pediatric Quality of Life Inventory as a reliable and effective tool for the measurement of quality of life among Pediatrics Pakistani population.

Keywords: primary school children, paediatric quality of life, exploratory factor analysis, Pakistan

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Authors: Nirav J. Patel, Kalpesh K. Dudani

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Partial discharge (PD) is the dissipation of energy caused by localized breakdown of insulation. Power transformers are one of the most important components in the electrical energy network. Insulation degradation of transformer is frequently linked to PD. This is why PD detection is used in power system to monitor the health of high voltage transformer. If such problem are not detected and repaired, the strength and frequency of PD may increase and eventually lead to the catastrophic failure of the transformer. This can further cause external equipment damage, fires and loss of revenue due to an unscheduled outage. Hence, reliable online PD detection is a critical need for power companies to improve personnel safety and decrease the probability of loss of service. The PD phenomenon is manifested in a variety of physically observable signals including Ultra High Frequency (UHF) radiation and Acoustic Disturbances, Electrical pulses. Acoustic method is based on sensing the radiated acoustic emission from discharge sites in the insulation. Propagated wave from the PD fault site are captured sensor are consequently pre-amplified, filtered, recorded and analyze.

Keywords: acoustic, partial discharge, perfectly matched layer, sensor

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Authors: Nik Abdul Rahim Nik Abdul Ghani, Mat Noor Mat Zain, Ahmad Dahlan Salleh

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Ownership of asset is an important aspect in ensuring the validity of sale contract. Nevertheless, in Islamic finance, the issue of beneficial ownership as practiced in the current system is seriously debated among Shariah scholars. It has been argued as violating the real concept of ownership (milkiyyah) in Shariah law. This article aims at studying the status of beneficial ownership from the Shariah perspective. This study begins with examining the meaning of ownership and its attributes from the Islamic point of view and followed by the discussion on the origin of beneficial ownership from the legal perspective. The approach that is applied to clarify the concept of beneficial ownership is content analysis. Subsequently, this study explains some current applications of beneficial ownership in Islamic finance to be analyzed further from the Shariah aspect. The research finding suggests that beneficial ownership should be recognized as a real ownership due to the fact that Shariah allows the transfer of ownership after the execution of offer (ijab) and acceptance (qabul).

Keywords: beneficial ownership, ownership, Islamic finance, parameter

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Authors: Rodrigo Guimarães Santos

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The quality of public transport services has been considered as a critical factor by their users and also by users of individual transport. Thus, this dissertation aims to adapt a model that assesses the quality of public transport and determines its level of service based on the views of its users. The methodology is widely used by marketers and allows measuring the quality of services by assessing the perceptions and expectations of users. The adapted SERVQUAL was tested with users of public transport service users and car in Brasília-DF, city of Brazil. This research involved 241 questionnaires answered by people living in the various administrative regions of Brasília-DF. The analysis of the determinants pointed out that the quality of the public transport service offered in the city is low and users of public transport and cars have a high degree of expectations for improvement in all tested determinants. This method enabled the identification of the most critical determinants and those needing strategic actions for continuous improvement of quality. Adapting the SERVQUAL for a public transport service was satisfactory and demonstrated applicability to internal and external services, including measuring the public transport services in other cities with the opinion of the users.

Keywords: transportation services, quality services, servqual scale and marketing services

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Authors: Arash Najmaei, Jo Rhodes, Peter Lok, Zahra Sadeghinejad

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In this article, we endeavor to explore how a new business model comes into existence in the Australian cloud-computing eco-system. Findings from multiple case study methodology reveal that to develop a business model new ventures adopt a three-phase approach. In the first phase, labelled as business model ideation (BMID) various ideas for a viable business model are generated from both internal and external networks of the entrepreneurial team and the most viable one is chosen. Strategic consensus and commitment are generated in the second phase. This phase is a business modelling strategic action phase. We labelled this phase as business model strategic commitment (BMSC) because through commitment and the subsequent actions of executives resources are pooled, coordinated and allocated to the business model. Three complementary sets of resources shape the business model: managerial (MnRs), marketing (MRs) and technological resources (TRs). The third phase is the market-test phase where the business model is reified through the delivery of the intended value to customers and conversion of revenue into profit. We labelled this phase business model actualization (BMAC). Theoretical and managerial implications of these findings will be discussed and several directions for future research will be illuminated.

Keywords: entrepreneur business model, high-tech venture, resources, conversion of revenue

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Authors: Farid M. Abdel-Rahim

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In this study, Se90Te7Cu3 chalcogenide glass was prepared using the melt quenching technique. The amorphous nature of the as prepared samples was confirmed by scanning electron microscope (SEM). Result of differential scanning calorimetric (DSC) under nonisothermal condition on composition bulk materials are reported and discussed. It shows that these glasses exhibit a single-stage glass transition and a single-stage crystallization on heating rates. The glass transition temperature (Tg), the onset crystallization (Tc), the crystallization temperature (Tp), were found by dependent on the composition and heating rates. Activation energy for glass transition (Et), activation energy of the amorphous –crystalline transformation (Ec), crystallization reaction rate constant (Kp), (n) and (m) are constants related to crystallization mechanism of the bulk samples have been determined by different formulations.

Keywords: chalcogenides, heat treatment, DSC, SEM, glass transition, thermal analysis

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Authors: Lule Basha, Eralda Gjika

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This study is focused on analyzing climate change in Albania and its potential effects on cereal yields. Initially, monthly temperature and rainfalls in Albania were studied for the period 1960-2021. Climacteric variables are important variables when trying to model cereal yield behavior, especially when significant changes in weather conditions are observed. For this purpose, in the second part of the study, linear and nonlinear models explaining cereal yield are constructed for the same period, 1960-2021. The multiple linear regression analysis and lasso regression method are applied to the data between cereal yield and each independent variable: average temperature, average rainfall, fertilizer consumption, arable land, land under cereal production, and nitrous oxide emissions. In our regression model, heteroscedasticity is not observed, data follow a normal distribution, and there is a low correlation between factors, so we do not have the problem of multicollinearity. Machine-learning methods, such as random forest, are used to predict cereal yield responses to climacteric and other variables. Random Forest showed high accuracy compared to the other statistical models in the prediction of cereal yield. We found that changes in average temperature negatively affect cereal yield. The coefficients of fertilizer consumption, arable land, and land under cereal production are positively affecting production. Our results show that the Random Forest method is an effective and versatile machine-learning method for cereal yield prediction compared to the other two methods.

Keywords: cereal yield, climate change, machine learning, multiple regression model, random forest

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Authors: E. Eroglu, S. Semsit, E. Sener, U.S. Sener

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In Electromagnetics, there are three canonical boundary value problem with given initial conditions for the electromagnetic field sought, namely: Cavity Problem, Waveguide Problem, and External Problem. The Cavity Problem and Waveguide Problem were rigorously studied and new results were arised at original works in the past decades. In based on studies of an analytical time domain method Evolutionary Approach to Electromagnetics (EAE), electromagnetic field strength vectors produced by a time dependent source function are sought. The fields are took place in L2 Hilbert space. The source function that performs signal transferring, energy and surplus of energy has been demonstrated with all clarity. Depth of the method and ease of applications are emerged needs of gathering obtained results. Main discussion is about perfect electric conductor and hollow waveguide. Even if well studied time-domain modes problems are mentioned, specifically, the modes which have a hollow (i.e., medium-free) cross-section domain are considered.

Keywords: evolutionary approach to electromagnetics, time-domain waveguide mode, Neumann problem, Dirichlet boundary value problem, Klein-Gordon

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Authors: Pegah Zamani

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This multidisciplinary study interrogates the reformulation of socio-ecological systems by bringing different disciplines together and incorporating ecological, social, and technological components to the sustainable design. The study seeks for a holistic sustainable system to understand the multidimensional impact of the evolving innovative technologies on responding to the variable socio-environmental conditions. Through a range of cases, from the vernacular built spaces to the sophisticated optimized systems, the research unfolds how far the environmental elements would impact the performance of a sustainable building, its micro-climatic ecological requirements, and its human inhabitation. As a product of the advancing technologies, an optimized and environmentally responsive building offers new identification, and realization of the built space through reformulating the connection to its internal and external environments (such as solar, thermal, and airflow), as well as its dwellers. The study inquires properties of optimized buildings, by bringing into the equation not only the environmental but also the socio-cultural, morphological, and phenomenal factors. Thus, the research underlines optimized built space as a product and practice which would not be meaningful without addressing and dynamically adjusting to the diversity and complexity of socio-ecological systems.

Keywords: ecology, morphology, socio-ecological systems, sustainability

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Authors: Mona Almansoori, Ahmed Mustafa, Ahmad Elshamy

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Wireless sensor network was formed by a combination of nodes, systematically it transmitting the data to their base stations, this transmission data can be easily compromised if the limited processing power and the data consistency from these nodes are kept in mind; there is always a discussion to address the secure data transfer or transmission in actual time. This will present a mechanism to securely transmit the data over a chain of sensor nodes without compromising the throughput of the network by utilizing available battery resources available in the sensor node. Our methodology takes many different advantages of Z-MAC protocol for its efficiency, and it provides a unique key by sharing the mechanism using neighbor node MAC address. We present a light weighted data integrity layer which is embedded in the Z-MAC protocol to prove that our protocol performs well than Z-MAC when we introduce the different attack scenarios.

Keywords: hybrid MAC protocol, data integrity, lightweight encryption, neighbor based key sharing, sensor node dataprocessing, Z-MAC

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Authors: Aynur Aker, Hasan Kaya

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Al-12.6wt.%Si-2wt.%Cu ternary alloy of near eutectic composition was directionally solidified upward at a constant temperature gradient in a wide range of growth rates (V=8.25-165.41 µm/s). The microstructures (λ), microhardness (HV), tensile stress (σ) and electrical resistivity (ρ) were measured from directionally solidified samples. The dependence of microstructures, microhardness and electrical resistivity on growth rate (V) was also determined by statistical analysis. According to these results, it has been found that for increasing values of V, the values of HV, σ and ρ increase. Variations of electrical resistivity for casting Al-Si-Cu alloy were also measured at the temperature in range 300-500 K. The enthalpy (ΔH) and the specific heat (Cp) for the Al-Si-Cu alloy were determined by differential scanning calorimeter (DSC) from heating trace during the transformation from solid to liquid. The results obtained in this work were compared with the similar experimental results in the literature.

Keywords: Al-Si-Cu alloy, microstructures, micro-hardness, tensile stress electrical resistivity, enthalpy

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Authors: Jan Schmidt, Pierre Köhring

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Permanently excited machines are set up with magnets that are made of highly energetic magnetic materials. Inherently, the permanent magnets warm up while the machine is operating. With an increasing temperature, the electromotive force and hence the degree of efficiency decrease. The reasons for this are slot harmonics and distorted armature currents arising from frequency inverter operation. To prevent or avoid demagnetizing of the permanent magnets it is necessary to ensure that the magnets do not excessively heat up. Demagnetizations of permanent magnets are irreversible and a breakdown of the electrical machine is inevitable. For the design of an electrical machine, the knowledge of the behavior of heating under operating conditions of the permanent magnet is of crucial importance. Therefore, a calculation model is presented with which the machine designer can easily calculate the eddy current losses in the magnetic material.

Keywords: analytical model, eddy current, losses, lattice network, permanent magnet

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Authors: Anne E. Goodenough

Abstract:

Students often learn best ‘on the job’ through holistic real-world projects. They need real-world experiences to make classroom learning applicable and to increase their employability. Academics typically value working on projects where new knowledge is created and have a genuine desire to help students engage with learning and develop new skills. They might also have institutional pressure to enhance student engagement, retention, and satisfaction. External organizations - especially non-governmental bodies, charities, and small enterprises - often have fundamental and pressing questions, but lack the manpower and academic expertise to answer them effectively. They might also be on the lookout for talented potential employees. This study examines ways in which these diverse requirements can be met simultaneously by creating three-way projects that provide excellent academic and real-world outcomes for all involved. It studied a range of innovative projects across natural sciences (biology, ecology, physical geography and social sciences (human geography, sociology, criminology, and community engagement) to establish how to best harness the potential of this powerful approach. Focal collaborations included: (1) development of practitioner-linked modules; (2) frameworks where students collected/analyzed data for link organizations in research methods modules; (3) placement-based internships and dissertations; and (4) immersive fieldwork projects in novel locations to allow students engage first-hand with contemporary issues as diverse as rhino poaching in South Africa, segregation in Ireland, and gun crime in Florida. Although there was no ‘magic formula’ for success, the approach was found to work best when small projects were developed that were achievable in a short time-frame, both to tie into modular curricula and meet the immediacy expectations of many link organizations. Bigger projects were found to work well in some cases, especially when they were essentially a series of linked smaller projects, either running concurrently or successively with each building on previous work. Opportunities were maximized when there were tangible benefits to the link organization as this generally increased organization investment in the project and motivated students too. The importance of finding the right approach for a given project was found to be key: it was vital to ensure that something that could work effectively as an independent research project for one student, for example, was not shoehorned into being a project for multiple students within a taught module. In general, students were very positive about collaboration projects. They identified benefits to confidence, time-keeping and communication, as well as conveying their enthusiasm when their work was of benefit to the wider community. Several students have gone on to do further work with the link organization in a voluntary capacity or as paid staff, or used the experiences to help them break into the ever-more competitive job market in other ways. Although this approach involves a substantial time investment, especially from academics, the benefits can be profound. The approach has strong potential to engage students, help retention, improve student satisfaction, and teach new skills; keep the knowledge of academics fresh and current; and provide valuable tangible benefits for link organizations: a real triple win.

Keywords: authentic learning, curriculum development, effective education, employability, higher education, innovative pedagogy, link organizations, student experience

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