Search results for: multidisciplinary investigation

Authors: Alexander Glebovskiy

Abstract:

Practitioners charged with fraud prevention and investigation strongly rely on the Fraud Triangle framework developed by Joseph T. Wells in 1997 while analyzing the causes of fraud at business organizations. The Fraud Triangle model explains fraud by elements such as pressure, opportunity, and rationalization. This view is not fully suitable for effective fraud prevention as the Fraud Triangle model provides limited insight into the causation of fraud. Fraud is a multifaceted phenomenon, the contextual factors of which may not fit into any framework. Employee criminal behavior in business organizations is influenced by environmental, individual, and organizational aspects. Therefore, further criminogenic factors and processes facilitating fraud in organizational settings need to be considered in the root-cause analysis: organizational culture, leadership style, groupthink effect, isomorphic behavior, crime of obedience, displacement of responsibility, lack of critical thinking and unquestioning conformity and loyalty.

Keywords: criminogenesis, fraud triangle, fraud prevention, organizational culture

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Authors: Henry Okechukwu Onyeiwu

Abstract:

Nigeria, with its rich tapestry of ethnicities, cultures, and religions, serves as a critical case study in understanding how law influences and shapes collective identities. This abstract delves into the historical context of legal systems in Nigeria, examining the colonial legacies that have influenced contemporary laws and how these laws interact with traditional practices and beliefs. This study examines the critical role of law in shaping and transforming collective identities in Nigeria, a nation characterized by its rich tapestry of ethnicities, cultures, and religions. The legal framework in Nigeria has evolved in response to historical, social, and political dynamics, influencing the way communities perceive themselves and interact with one another. This research highlights the interplay between law and collective identity, exploring how legal instruments, such as constitutions, statutes, and judicial rulings, have contributed to the formation, negotiation, and reformation of group identities over time. Moreover, contemporary legal debates surrounding issues such as citizenship, resource allocation, and communal conflicts further illustrate the law's role in identity formation. The legal recognition of different ethnic groups fosters a sense of belonging and collective identity among these groups, yet it simultaneously raises questions about inclusivity and equality. Laws concerning indigenous rights and affirmative action are essential in this discourse, as they reflect the necessity of balancing majority rule with minority rights—a challenge that Nigeria continues to navigate. By employing a multidisciplinary approach that integrates legal studies, sociology, and anthropology, the study analyses key historical milestones, such as colonial legal legacies, post-independence constitutional developments, and ongoing debates surrounding federalism and ethnic rights. It also investigates how laws affect social cohesion and conflict among Nigeria's diverse ethnic groups, as well as the role of law in promoting inclusivity and recognizing minority rights. Case studies are utilized to illustrate practical examples of legal transformations and their impact on collective identities in various Nigerian contexts, including land rights, religious freedoms, and ethnic representation in government. The findings reveal that while the law has the potential to unify disparate groups under a national identity, it can also exacerbate divisions when applied inequitably or favouring particular groups over others. Ultimately, this study aims to shed light on the dual nature of law as both a tool for transformation and a potential source of conflict in the evolution of collective identities in Nigeria. By understanding these dynamics, policymakers and legal practitioners can develop strategies to foster unity and respect for diversity in a complex societal landscape.

Keywords: law, collective identity, Nigeria, ethnicity, conflict, inclusion, legal framework, transformation

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Authors: Sedrak Vardanyan

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The investigation of the vibrational character of magnetic cylindrical shells placed in an axial magnetic field has important practical applications. In this work, we study the vibrational behaviour of such a cylindrical shell by making use of the so-called exact space treatment, which does not assume any hypothesis. We discuss the effects of several practically important boundary conditions on the vibrations of the described setup. We find that, for some cases of boundary conditions, e.g. clamped, simply supported or peripherally earthed, as well as for some values of the wave numbers, the vibrational frequencies of the shell are approximately zero. The theoretical and numerical exploration of this fact confirms that the vibrations are absent or attenuate very rapidly. For all the considered cases, the imaginary part of the frequencies is negative, which implies stability for the vibrational process.

Keywords: bending vibrational frequencies, exact space treatment, free vibrations, magnetic cylindrical shells

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Authors: Hocine Terrab , Abdelhafid Bayadi, Adel Kara, Ayman El-Hag

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Insulator flashover under polluted conditions has been a serious threat on the reliability of power systems. It is known that the flashover process is mainly affected by the environmental conditions such as; the pollution level and humidity. Those are the essential parameters influencing the wetting process. This paper presents an investigation of the characteristics of leakage current (LC) developed on the surface of porcelain insulator at contaminated conditions under AC voltage. The study is done in an artificial fog chamber and the LC is characterized for different stages; dry, wetted and presence of discharge activities. Time-frequency and spectral analysis are adopted to calculate the evolution of LC characteristics with various stages prior to flashover occurrence. The preliminary results could be used in analysing the LC to develop more effective diagnosis of early signs of dry band arcing as an indication for insulation washing.

Keywords: flashover, harmonic components, leakage current, phase angle, statistical analysis

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Authors: M. Guemmadi, A. Ouibrahim

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This numerical investigation aims to evaluate how a viscoelastic lubricant described by a generalized Maxwell model, affects the pressure distribution, the load capacity and thermal effect in a journal bearing lubrication. We use for the purpose the CFD package software completed by adapted user define functions (UDFs) to solve the coupled equations of momentum, of energy and of the viscoelastic model (generalized Maxwell model). Two parameters, viscosity and relaxation time are involved to show how viscoelasticity substantially affect the pressure distribution, the load capacity and the thermal transfer by comparison to Newtonian lubricant. These results were also compared with the available published results.

Keywords: journal bearing, lubrication, Maxwell model, viscoelastic fluids, computational modelling, load capacity

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Authors: Tímea Gerzsenyi, Ágnes M. Ilosvai, László Vanyorek, Emma Szőri-Dorogházi

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DNA isolation is a crucial step in many molecular biological applications for diagnostic and research purposes. However, traditional extraction requires toxic reagents, and commercially available kits are expensive, this leading to the recently wide-spread method, the magnetic nanoparticle (MNP)-based DNA isolation. Different ferrite containing MNPs were examined and compared in their plasmid DNA isolation efficiency. Among the tested MNPs, one has never been used for the extraction of plasmid molecules, marking a distinct application. pDNA isolation process was optimized for each type of nanoparticle and the best protocol was selected based on different criteria: DNA quantity, quality and integrity. With the best-performing magnetic nanoparticle, which excelled in all aspects, further tests were performed to recover genomic DNA from bacterial cells and a protocol was developed.

Keywords: DNA isolation, nanobiotechnology, magnetic nanoparticles, protocol optimization, pDNA, gDNA

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Authors: Shahruhaida Adayu Mohd Paili, Abd Latif Abdul Rahman, Asmadi Mohammed Ghazali

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Digital library was developed by many organizations, especially universities. The digital library can be considered as a new information system. Digital library brings many benefits to the users. There are many researches that have investigated the importance of the digital library, the acceptance, and continuance use of digital library. The investigation towards the digital library is important and it is crucial to understand the reason why users accept and continued use of digital library. Users can search the information and available resources through the digital library website. It is important to know the user’s perception towards the aesthetics of the digital library. Besides that, because of digital library provided information to the users, the researcher also needed to investigate the quality of information in digital library. This study used Extending the Unified Theory of Acceptance and Use of Technology (UTAUT2) in order to know the user’s intention to continued use of digital library.

Keywords: digital library, aesthetics, information quality, intention to continued use of digital library, UTAUT2

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Authors: Petr Šimek

Abstract:

This work deals with the problem of synchronization of bus frames during transmission using USB (Universal Serial Bus). The principles for synchronization between USB and the non-deterministic CAN (Controller Area Network) bus will be described here. Furthermore, the work deals with ensuring the time sequence of communication frames when receiving from multiple communication bus channels. The structure of a general object for storing frames from different types of communication buses, such as CAN and LIN (Local Interconnect Network), will be described here. Finally, an evaluation of the communication throughput of bus frames for USB High speed will be performed. The creation of this architecture was based on the analysis of the communication of control units with a large number of communication buses. For the design of the architecture, a test HW with a USB-HS interface was used, which received previously known messages, which were compared with the received result. The result of this investigation is the block architecture of the control program for test HW ensuring correct data transmission via the USB bus.

Keywords: analysis, CAN, interface, LIN, synchronization, USB

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Authors: Yusuf Seller

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Classical Arabic poetry was narrated by the followers of poets, who were memorizing and repeating all the couplets of their master constantly. Although the students established their own styles, it was very natural for them to reflect the style and expression of their masters. This reflection was discussed in classical Arabic literary criticism and rhetoric (al-‘ilm al-balagha), as “al-Sariqah al-shiriyyah”, plagiarism in poetry. This study tests the claim that the reflection of the master's style and expressions in the student's poetry cannot be considered plagiarism. In addition, one of the goals of this essay is also to investigate the methodological emergence of plagiarism phenomena in classical Arabic poetry. The investigation of the methodological origins of plagiarism helps us see the relationship of plagiarism with literary property and the extent of the property`s authenticity. Therefore, the focus is directed towards uncovering the underlying ethical principles governing literary works and academic research in classical Arabic poetry.

Keywords: Arabic literary criticism, classical Arabic poetry, plagiarism, al-Sariqah al-shiriyyah

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Authors: Brahim Mahfoud, Rachid Bessaïh

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In this paper, a numerical study of steady and oscillatory flows with heat transfer submitted to an axial magnetic field is studied. The governing Navier-Stokes, energy, and potential equations along with appropriate boundary conditions are solved by using the finite-volume method. The flow and temperature fields are presented by stream function and isotherms, respectively. The flow between counter-rotating end disks is very unstable and reveals a great richness of structures. The results are presented for various values of the Hartmann number, Ha=5, 10, 20, and 30, and Richardson numbers , Ri=0, 0.5, 1, 2, and 4, in order to see their effects on the value of the critical Reynolds number, Recr. Stability diagrams are established according to the numerical results of this investigation. These diagrams put in evidence the dependence of Recr with the increase of Ha for various values of Ri.

Keywords: swirling, counter-rotating end disks, magnetic field, oscillatory, cylinder

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Authors: Tarique Jamil Khan, Swapnil Pande

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The investigation deals with the study of heat transfer enhancement using protruded square fin. This study is enough to determine whether protrusion in forced convection is enough to enhance the rate of heat transfer. It includes the results after performing experiments by using a plane rectangular fin of aluminum material and the same dimension rectangular fin of the same material but having protruded circular shape extended normally. The fins made by a sand casting method. The results clearly mentioned that the protruded surface is effective enough to enhance the rate of heat transfer. This research investigates a modern fin topologies heat transfer characteristics that will clearly outdated the conventional fin to increase the rate of heat transfer. Protruded fins improve the rate of heat transfer compared to solid fin by varying shape of the protrusion in diameter and height.

Keywords: heat transfer enhancement, forced convection, protruted fin, rectangular fin

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Authors: Ashkan Shafee, Ahmad Fahimifar

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There is a growing demand for construction of high-rise buildings and infrastructures in large cities, which sometimes require deep excavations in the vicinity of pile foundations. In this study, a two-dimensional finite element analysis is used to gain insight into the response of pile groups adjacent to deep excavations in sand. The numerical code was verified by available experimental works, and a parametric study was performed on different working load combinations, excavation depth and supporting system. The results show that the simple two-dimensional plane strain model can accurately simulate the excavation induced changes on adjacent pile groups. It was found that further excavation than pile toe level and also inclined loading on adjacent pile group can severely affect the serviceability of the foundation.

Keywords: deep excavation, inclined loading, lateral deformation, pile group

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Authors: Tarek Litim, Ouahiba Taamallah

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The present paper is an investigation of the effect of burnishing on the surface integrity of a component made of 15NiCr6 steel. This work shows a statistical study based on regression, and Taguchi's design has allowed the development of mathematical models to predict the output responses as a function of the technological parameters studied. The response surface methodology (RSM) showed a simultaneous influence of the burnishing parameters and observe the optimal processing parameters. ANOVA analysis of the results resulted in the validation of the prediction model with a determination coefficient R=90.60% and 92.41% for roughness and hardness, respectively. Furthermore, a multi-objective optimization allowed to identify a regime characterized by P=10kgf, i=3passes, and f=0.074mm/rev, which favours minimum roughness and maximum hardness. The result was validated by the desirability of D= (0.99 and 0.95) for roughness and hardness, respectively.

Keywords: 15NiCr6 steel, burnishing, surface integrity, Taguchi, RSM, ANOVA

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Authors: H. Fazlinejad, A. Halvaee

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In this study, characteristics of ATIG welds using ZnO flux on aluminum was investigated and compared with TIG welds. Autogenously AC-ATIG bead on plate welding was applied on Al1050 plate with a coating of ZnO as the flux. Different levels of welding current and flux layer thickness was considered to study the effect of heat input and flux quantity on ATIG welds and was compared with those of TIG welds. Geometrical investigation of the weld cross sections revealed that penetration depth of the ATIG welds with ZnO flux, was increased up to 2 times in some samples compared to the TIG welds. Optical metallographic and Scanning Electron Microscopy (SEM) observations revealed similar microstructures in TIG and ATIG welds. Composition of the ATIG welds slag was also analyzed using X-ray diffraction. In both TIG and ATIG samples, the lowest values of microhardness were observed in the HAZ.

Keywords: ATIG, active flux, weld penetration, Al 1050, ZnO

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Authors: Zaaraoui Abdelkader, Kerfah Rabeh, Noura Belkheir, Matene Elhacene

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The trapezoidal bluff body is a typical configuration of vortex shedding bodies. The aim of this work is to study flow behaviour over a trapezoidal cylinder at low Reynolds number. The geometry was constructed from a prototype device for measuring the volumetric flow-rate by counting vortices. Simulations were run for this geometry under steady and unsteady flow conditions using finite volume discretization. Laminar flow was investigated in this model with rigid walls and homogeneous incompressible Newtonian fluid. Calculations were performed for Reynolds number range 5 ≤ Re ≤ 180 and several flow parameters were documented. The present computations are in good agreement with the experimental observations and the numerical calculations by several investigators.

Keywords: bluff body, confined flow, numerical calculations, steady and unsteady flow, vortex shedding flow meter

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Authors: Wiem Gadri

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This study delves into the intriguing properties of Pisot and Salem numbers within the framework of formal Laurent series over finite fields, a domain where these numbers’ spectral charac-teristics, Λm(β) and lm(β), have yet to be fully explored. Utilizing a methodological approach that combines algebraic number theory with the analysis of power series, we extend the foundational work of Erdos, Joo, and Komornik to this new setting. Our research uncovers bounds for lm(β), revealing how these depend on the degree of the minimal polynomial of β and thus offering a novel characterization of Pisot and Salem formal power series. The findings significantly contribute to our understanding of these numbers, highlighting their distribution and properties in the context of formal power series. This investigation not only bridges number theory with formal power series analysis but also sets the stage for further interdisciplinary research in these areas.

Keywords: Pisot numbers, Salem numbers, formal power series, over a finite field

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Authors: M. Salih Taci, N. Tayebi, I. Bozkır

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In this paper, the equivalent circuit of the ideal single-phase power transformer with its appropriate voltage current measurement was presented. The calculated values of the voltages and currents of the different connections single phase normal transformer and the results of the simulation process are compared. As it can be seen, the calculated results are the same as the simulated results. This paper includes eight possible different transformer connections. Depending on the desired voltage level, step-down and step-up application transformer is considered. Modelling and analysis of a system consisting of an equivalent source, transformer (primary and secondary), and loads are performed to investigate the combinations. The obtained values are simulated in PSpice environment and then how the currents, voltages and phase angle are distributed between them is explained based on calculation.

Keywords: transformer, simulation, equivalent model, parallel series combinations

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Authors: Vinita Choudhary

Abstract:

The solidly mounted resonator (SMR) is a bulk acoustic wave-based device consisting of a piezoelectric layer sandwiched between two electrodes upon Bragg reflectors, which then are attached to a substrate. To transform the effective acoustic impedance of the substrate to a near zero value, the Bragg reflectors are composed of alternating high and low acoustic impedance layers of quarter-wavelength thickness. In this work presents the design and investigation of acoustic Bragg reflectors (ABRs) for solidly mounted bulk acoustic wave resonators through analysis and simulation. This performance of the resonator is analyzed using 1D Mason modeling. The performance parameters are the effect of Bragg pairs number on transmissivity, reflectivity, insertion loss, the electromechanical and quality factor of the 5GHz operating resonator.

Keywords: bragg reflectors, SMR, insertion loss, quality factor

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Authors: Arash Mir Abdolah Lavasani, M. Ebrahimisabet

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In this paper, the 2-D unsteady viscous flow around two cam shaped cylinders in tandem arrangement is numerically simulated in order to study the characteristics of the flow in turbulent regimes. The investigation covers the effects of high subcritical and supercritical Reynolds numbers and L/D ratio on total drag coefficient. The equivalent diameter of cylinders is 27.6 mm The space between center to center of two cam shaped cylinders is define as longitudinal pitch ratio and it varies in range of 1.5 < L/D < 6. Reynolds number base on equivalent circular cylinder varies in range of 27×103 < Re < 166×103 Results show that drag coefficient of both cylinders depends on pitch ratio. However drag coefficient of downstream cylinder is more dependent on the pitch ratio.

Keywords: cam shaped, tandem, numerical, drag coefficient, turbulent

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Authors: Antonio Martín-Pardo

Abstract:

With regard to the context in which this paper is inserted, it is noteworthy that the current criminal policy model in which we find immersed, denominated by some doctrine sector as the citizen security model, is characterized by a marked tendency towards the discredit of expert knowledge. This type of technic knowledge has been displaced by the common sense and by the daily experience of the people at the time of legislative drafting, as well as by excessive attention to the short-term political effects of the law. Despite this criminal-political adverse scene, we still find valuable efforts in the side of experts to bring some rationality to the legislative development. This is the case of the proposal for a new cannabis regulation model in Spain carried out by the Cannabis Policy Studies Group (hereinafter referred as ‘GEPCA’). The GEPCA is a multidisciplinary group composed by authors with multiple/different orientations, trajectories and interests, but with a common minimum objective: the conviction that the current situation regarding cannabis is unsustainable and, that a rational legislative solution must be given to the growing social pressure for the regulation of their consumption and production. This paper details the main lines through which this technical proposal is developed with the purpose of its dissemination and discussion in the Congress. The basic methodology of the proposal is inductive-expository. In that way, firstly, we will offer a brief, but solid contextualization of the situation of cannabis in Spain. This contextualization will touch on issues such as the national regulatory situation and its relationship with the international context; the criminal, judicial and penitentiary impact of the offer and consumption of cannabis, or the therapeutic use of the substance, among others. In second place, we will get down to the business properly by detailing the minutia of the three main cannabis access channels that are proposed. Namely: the regulated market, the associations of cannabis users and personal self-cultivation. In each of these options, especially in the first two, special attention will be paid to both, the production and processing of the substance and the necessary administrative control of the activity. Finally, in a third block, some notes will be given on a series of subjects that surround the different access options just mentioned above and that give fullness and coherence to the proposal outlined. Among those related issues we find some such as consumption and tenure of the substance; the issue of advertising and promotion of cannabis; consumption in areas of special risk (work or driving v. g.); the tax regime; the need to articulate evaluation instruments for the entire process; etc. The main conclusion drawn from the analysis of the proposal is the unsustainability of the current repressive system, clearly unsuccessful, and the need to develop new access routes to cannabis that guarantee both public health and the rights of people who have freely chosen to consume it.

Keywords: cannabis regulation proposal, cannabis policies studies group, criminal policy, expertise participation

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Authors: Jin-Lung Guan, Jyh-Cherng Gu, Chun-Wei Huang, Hsin-Hung Chang

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This investigation develops a revisable method for estimating the estimate value of equivalent 10 Hz voltage flicker (DV10) of a DC Electric Arc Furnace (EAF). This study also discusses three 161kV DC EAFs by field measurement, with those results indicating that the estimated DV10 value is significantly smaller than the survey value. The key point is that the conventional means of estimating DV10 is inappropriate. There is a main cause as the assumed Qmax is too small. Although DC EAF is regularly operated in a constant MVA mode, the reactive power variation in the Main Transformer (MT) is more significant than that in the Furnace Transformer (FT). A substantial difference exists between estimated maximum reactive power fluctuation (DQmax) and the survey value from actual DC EAF operations. However, this study proposes a revisable method that can obtain a more accurate DV10 estimate than the conventional method.

Keywords: voltage flicker, dc EAF, estimate value, DV10

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Authors: Uzu-Kuei Hsu, Chang-Hsien Tai, Kai-Wun Jin

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When sinters are filled into the cooler from the sintering machine, and the non-uniform distribution of the sinters leads to uneven cooling. This causes the temperature difference of the sinters leaving the cooler to be so large that it results in the conveyors being deformed by the heat. The present work applies CFD method to investigate the thermo flowfield phenomena in a sinter cooler by the Porous Media Model. Using the obtained experimental data to simulate porosity (Ε), permeability (κ), inertial coefficient (F), specific heat (Cp) and effective thermal conductivity (keff) of the sinter packed beds. The physical model is a similar geometry whose Darcy numbers (Da) are similar to the sinter cooler. Using the Cooling Index (CI) and Uniformity Index (UI) to analyze the thermo flowfield in the sinter packed bed obtains the cooling performance of the sinter cooler.

Keywords: porous media, sinter, cooling index (CI), uniformity index (UI), CFD

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Authors: Paata Sitchinava

Abstract:

It has been studied phenomena subjected on the water physical (hydrophysical, mineralogy containing, specific hydrophysical) class of heavy clay soils of the Colchis lowland, according to various categories and forms of the porous water, which will be the base of the distributed used methods of the engineering practice and reclamation effectiveness evaluation. According to of clay grounds data, it has been chosen three research bases section in the central part of lowland, where has implemented investigation works by using a special program. It has been established, that three of cuts are somewhat identical, and by morphological grounds separated layers are the difference by Gallic quality. It has been implemented suitable laboratory experimental research at the samples taken from the cuts, at the base of these created classification mark of physical-technical characteristic, which is the base of suitable calculation of hydrophysical researches.

Keywords: Colchis lowland, drainage, water, soil-ground

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Authors: M. Mourad, K. Mahmoud

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Recently hybrid vehicles have become a major concern as one alternative vehicles. This type of hybrid vehicle contributes greatly to reducing pollution. Therefore, this work studies the influence of electrification phase of hybrid electric vehicle on emission of vehicle at different road conditions. To accomplish this investigation, a simulation model was used to evaluate the external characteristics of the hybrid electric vehicle according to variant conditions of road resistances. Therefore, this paper reports a methodology to decrease the vehicle emission especially greenhouse gas emission inside cities. The results show the effect of electrification on vehicle performance characteristics. The results show that CO₂ emission of vehicle decreases up to 50.6% according to an urban driving cycle due to applying the electrification strategy for hybrid electric vehicle.

Keywords: electrification strategy, hybrid electric vehicle, driving cycle, CO2 emission

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Authors: Megha, Diksha, Seema Rani, Balwinder Kaur, Harminder Kaur

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Fe₃O₄@SiO₂@SB functionalized magnetic nanoparticles were synthesized and used to detect heavy metal ions such as Pb²⁺, Hg²⁺, and Cd²⁺ in water. The formation of Fe₃O₄@SiO₂@SB nanocatalyst was confirmed by XRD, SEM, TEM, and IR. The simultaneous determination of analyte cations was carried out using square wave anodic stripping voltammetry (SWASV). Investigation and optimisation were done to study how experimental variables affected the performance of the modified magnetic electrode. Pb²⁺, Hg²⁺, and Cd²⁺ were successfully detected using the designed sensor in the presence of various possibly interfering ions. The recovery rate was found to be 97.5% for Pb²⁺, 96.2% for Hg²⁺, 103.5% for Cd²⁺. The electrochemical sensor was also employed to determine the presence of heavy metal ions in drinking water samples, which are well below the World Health Organization (WHO) guidelines.

Keywords: magnetic nanoparticles, heavy metal ions, electrochemical sensor, environmental water samples

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Authors: Zlatina Peteva, Stanislava Georgieva, Mona Stancheva, Lubomir Makedonsky

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Yessotoxins (YTX) and pectenotoxins (PTX) are lipophilic polyether marine biotoxins that accumulate in shellfish and are regulated in the European Union. Aim of this study is investigation of the presence of YTXs and PTXs in Black Sea mussel (Mytilus galloprovincialis) on the North Black Sea cast of Bulgaria. YTX and PTX-2 have been identified in samples of the digestive glands of wild and cultivated samples. Mussel samples are harvested from two locations in important farming area on the Bulgarian North Black Sea coast in the period September 2016 – May 2017. Samples are analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS). In about 50 % of the samples analyzed the obtained concentration of YTX ranged from 10 – 5000 pg/g hepatopancreas and PTX-2 ranged from 300-7000 pg/g hepatopancreas. This is to our knowledge the first report of occurrence of lipophilic toxins in mussels from Bulgaria.

Keywords: yessotoxins, pectenotoxins, Black sea, mussels

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Authors: Ehsan Heidaryan

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Gas hydrate sediments are ice like permafrost in deep see and oceans. Methane production in sequestration process and reducing atmospheric carbon dioxide, a main source of greenhouse gas, has been accentuated recently. One focus is capture, separation, and sequestration of industrial carbon dioxide. As a hydrate former, carbon dioxide forms hydrates at moderate temperatures and pressures. This phenomenon could be utilized to capture and separate carbon dioxide from flue gases, and also has the potential to sequester carbon dioxide in the deep seabeds. This research investigated the effect of synthetic surfactants on carbon dioxide hydrate formation, catalysis and consequently, methane production from hydrate permafrosts in sediments. It investigated the sequestration potential of carbon dioxide hydrates in ocean sediments. Also, the catalytic effect of biosurfactants in these processes was investigated.

Keywords: carbon dioxide, hydrate, sequestration, surfactant

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Authors: M. Yousaf, S. Usman

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The present study focused on the investigation of the effects of roughness elements on heat transfer during natural convection in a rectangular cavity using a numerical technique. Roughness elements were introduced on the bottom hot wall with a normalized amplitude (A*/H) of 0.1. Thermal and hydrodynamic behavior was studied using a computational method based on Lattice Boltzmann method (LBM). Numerical studies were performed for a laminar natural convection in the range of Rayleigh number (Ra) from 103 to 106 for a rectangular cavity of aspect ratio (L/H) 2 with a fluid of Prandtl number (Pr) 1.0. The presence of the sinusoidal roughness elements caused a minimum to the maximum decrease in the heat transfer as 7% to 17% respectively compared to the smooth enclosure. The results are presented for mean Nusselt number (Nu), isotherms, and streamlines.

Keywords: natural convection, Rayleigh number, surface roughness, Nusselt number, Lattice Boltzmann method

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Authors: Feng Fu, Maria Karli

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In this paper, experimental studies were carried out to investigate the behaviour of recycled aggregate concrete (RAC). A number of compressive tests, tensile splitting tests, as well as impact tests were conducted. In the tests, different recycled aggregate replacement ratio, different mix design and different water to cement ratio have been chosen in the investigation. The behavior of the RAC concrete was investigated in detail. The results of the tests show that the water-cement ratio plays an important role in the strength of the concrete and RAC concrete exhibit sufficient strength in comparison to the normal aggregate concrete; the relevant design recommendations are also made.

Keywords: recycled aggregate concrete, compressive test, tensile splitting test, flexural strength test, impact test

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Authors: Pantip Kayee, Yuwadee Yaponha, Jiranit Pongtubthai

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This study focused on the determination of heavy metal concentration in wastewater and the investigation of heavy metal removal of wastewater treatment system of Suan Sunandha Rajabhat University. Heavy metals (Pb, Cu, Mn, Ni and Zn) were found in wastewater of Suan Sunandha Rajabhat University. Wastewater treatment systems of Suan Sunandha Rajabhat University showed the performance to remove heavy metals. However, heavy metals were still presented in effluent but these residue heavy metals were not over the standard for industrial wastewater. Wastewater treatment system can remove heavy metal by different process such as bioaccumulation by microorganism and biosorption on activated sludge.

Keywords: heavy metal, wastewater, bioaccumulation, biosorption

Procedia PDF Downloads 451