Search results for: structural efficiency

Authors: M. Ramesh, Manish K. Niranjan

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The electronic, structural and thermoelectric properties of Mg₂SiSn (110) surface are investigated within the framework of first principle density functional theory and semi classical Boltzmann approach. In particular, directional dependent thermoelectric properties such as electrical conductivity, thermal conductivity, Seebeck coefficient and figure of merit are explored. The (110)-oriented Mg₂SiSn surface exhibits narrow indirect band gap of ~0.17 eV. The thermoelectric properties are found to be significant along the y-axis at 300 K and along x-axis at 500 K. The figure of merit (ZT) for hole carrier concentration is found to be significantly large having magnitude 0.83 (along x-axis) at 500 K and 0.26 (y-axis) at 300 K. Our results suggest that Mg₂SiSn (110) surface is promising for various thermoelectric applications due to its overall good thermoelectric properties.

Keywords: thermoelectric, surface science, semiconducting silicide, first principles calculations

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Authors: Namrata Yaduvanshi, Shilpa Kapoor, Pooja Pawar, Sadhna Singh

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In the present paper, we have investigated the high-pressure structural phase transition and elastic properties of cerium mononitride. We studied theoretically the structural properties of this compound (CeN) by using the Improved Interaction Potential Model (IIPM) approach. This compound exhibits first order crystallographic phase transition from NaCl (B1) to tetragonal (BCT) phase at 37 GPa. The phase transition pressures and associated volume collapse obtained from present potential model (IIPM) show a good agreement with available theoretical data.

Keywords: phase transition, volume collapse, elastic constants, three body interaction

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Authors: S. V. Prabhakar Vattikuti, Chan Byon

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In this paper, we report a facile synthetic strategy of randomly disturbed Bi₂S₃ nanorods on WS₂ nanosheets, which are synthesized via a controlled hydrothermal method without surfactant under an inert atmosphere. We developed a simple hydrothermal method for the formation of heterostructured of Bi₂S₃/WS₂ with a large scale (>95%). The structural features, composition, and morphology were characterized by XRD, SEM-EDX, TEM, HRTEM, XPS, UV-vis spectroscopy, N₂ adsorption-desorption, and TG-DTA measurements. The heterostructured Bi₂S₃/WS₂ composite has significant photocatalytic efficiency toward the photodegradation of organic dye. The time-dependent UV-vis absorbance spectroscopy measurement was consistent with the enhanced photocatalytic degradation of rhodamine B (RhB) under visible light irradiation with the diminishing carrier recombination for the Bi₂S₃/WS₂ photocatalyst. Due to their marked synergistic effects, the supported Bi₂S₃ nanorods on WS₂ nanosheet heterostructures exhibit significant visible-light photocatalytic activity and stability for the degradation of RhB. A possible reaction mechanism is proposed for the Bi₂S₃/WS₂ composite.

Keywords: photocatalyst, heterostructures, transition metal disulfides, organic dye, nanorods

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Authors: S. A. Faizi, S. Yoshitomi

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The optimal design procedure of buckling restrained braces (BRBs) in reinforced concrete (RC) building structures can provide the distribution of horizontal stiffness of BRBs at each story, which minimizes story drift response of the structure under the constraint of specified total stiffness of BRBs. In this paper, a simple rule is proposed to convert continuous horizontal stiffness of BRBs into sectional sizes of BRB which are available from standardized section list assuming realistic structural design stage.

Keywords: buckling restrained brace, building engineering, optimal damper placement, structural engineering

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Authors: Genevaive Melendres

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School administrators face the reality of teachers losing their engagement, or schools losing the teachers. This study is then conducted to identify a structural model that best predict work engagement of private secondary teachers in Davao City. Ninety-three teachers from four sectarian schools and 56 teachers from four non-sectarian schools were involved in the completion of four survey instruments namely Organizational Climate Questionnaire, Leader Behavior Descriptive Questionnaire, Organizational Commitment Scales, and Utrecht Work Engagement Scales. Data were analyzed using frequency distribution, mean, standardized deviation, t-test for independent sample, Pearson r, stepwise multiple regression analysis, and structural equation modeling. Results show that schools have high level of organizational climate dimensions; leaders oftentimes show work-oriented and people-oriented behavior; teachers have high normative commitment and they are very often engaged at their work. Teachers from non-sectarian schools have higher organizational commitment than those from sectarian schools. Organizational climate and leadership behavior are positively related to and predict work engagement whereas commitment did not show any relationship. This study underscores the relative effects of three variables on the work engagement of teachers. After testing network of relationships and evaluating several models, a best-fitting model was found between leadership behavior and work engagement. The noteworthy findings suggest that principals pay attention and consistently evaluate their behavior for this best predicts the work engagement of the teachers. The study provides value to administrators who take decisions and create conditions in which teachers derive fulfillment.

Keywords: leadership behavior, organizational climate, organizational commitment, private secondary school teachers, structural model on work engagement

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Authors: Devendra Kumar Pandey, Debabrata Chakraborty

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The advancement in various concrete ingredients like plasticizers, additives and fibers, etc. has enabled concrete technologists to develop many viable varieties of special concretes in recent decades. Such various varieties of concrete have significant enhancement in green as well as hardened properties of concrete. A prudent selection of appropriate type of concrete can resolve many design and application issues in construction projects. This paper focuses on usage of self-compacting concrete, high early strength concrete, structural lightweight concrete, fiber reinforced concrete, high performance concrete and ultra-high strength concrete in the structures. The modified properties of strength at various ages, flowability, porosity, equilibrium density, flexural strength, elasticity, permeability etc. need to be carefully studied and incorporated into the design of the structures. The paper demonstrates various mixture combinations and the concrete properties that can be leveraged. The selection of such products based on the end use of structures has been proposed in order to efficiently utilize the modified characteristics of these concrete varieties. The study involves mapping the characteristics with benefits and savings for the structure from design perspective. Self-compacting concrete in the structure is characterized by high shuttering loads, better finish, and feasibility of closer reinforcement spacing. The structural design procedures can be modified to specify higher formwork strength, height of vertical members, cover reduction and increased ductility. The transverse reinforcement can be spaced at closer intervals compared to regular structural concrete. It allows structural lightweight concrete structures to be designed for reduced dead load, increased insulation properties. Member dimensions and steel requirement can be reduced proportionate to about 25 to 35 percent reduction in the dead load due to self-weight of concrete. Steel fiber reinforced concrete can be used to design grade slabs without primary reinforcement because of 70 to 100 percent higher tensile strength. The design procedures incorporate reduction in thickness and joint spacing. High performance concrete employs increase in the life of the structures by improvement in paste characteristics and durability by incorporating supplementary cementitious materials. Often, these are also designed for slower heat generation in the initial phase of hydration. The structural designer can incorporate the slow development of strength in the design and specify 56 or 90 days strength requirement. For designing high rise building structures, creep and elasticity properties of such concrete also need to be considered. Lastly, certain structures require a performance under loading conditions much earlier than final maturity of concrete. High early strength concrete has been designed to cater to a variety of usages at various ages as early as 8 to 12 hours. Therefore, an understanding of concrete performance specifications for special concrete is a definite door towards a superior structural design approach.

Keywords: high performance concrete, special concrete, structural design, structural lightweight concrete

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Authors: Pisut Painmanakul, Thawatchai Chintateerachai, Supanid Lertlapwasin, Nusara Rojvilavan, Tanun Chalermsinsuwan, Nattawin Chawaloesphonsiya, Onanong Larpparisudthi

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Conventional coagulation, advance oxidation process (AOPs), and the combined process were evaluated and compared for its suitability to treat the stabilized cutting-oil wastewater. The 90% efficiency was obtained from the coagulation at Al2(SO4)3 dosage of 150 mg/L and pH 7. On the other hands, efficiencies of AOPs for 30 minutes oxidation time were 10% for acoustic oxidation, 12% for acoustic oxidation with hydrogen peroxide, 76% for Fenton, and 92% sono-Fenton processes. The highest efficiency for effective oil removal of AOPs required large amount of chemical. Therefore, AOPs were studied as a post-treatment after conventional separation process. The efficiency was considerable as the effluent COD can pass the standard required for industrial wastewater discharge with less chemical and energy consumption.

Keywords: cutting oily-wastewater, advance oxidation process, sono-fenton, combined process

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Authors: Bukhari M. S. Sillah, Imran Khokhar, Muhammad Nauman Khan

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This paper studies the technical efficiency of Saudi banking sector using stochastic frontier model. A sample of 12 banks over the period 2000-2011 is selected to investigate their technical efficiencies in mobilizing deposits, producing investment and generating income. The banks are categorized as Saudi-owned banks, Saudi-foreign-owned banks and Islamic banks. The findings show some consistent pattern of these bank types; and there exist significant disparities among the banks in term of technical efficiency. The Banque Saudi Fransi stands out as a benchmark bank for the industry, and it is a Saudi-foreign owned bank type. The Saudi owned bank types have shown fluctuating performance during the period; and the Islamic bank types are no significantly different from Saudi-owned bank types.

Keywords: technical efficiency, production frontier model, Islamic banking

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Authors: S. Nqayi

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Understanding the structural, electronic, and magnetic properties of nanomaterials is essential for developing next-generation electronic and spintronic devices, contributing to the progress of nanoscience and nanotechnology applications. Multiferroic materials, with intimately coupled ferroic-order parameters, are widely considered to breed fascinating physical properties and provide unique opportunities for the development of next-generation devices, like multistate non-volatile memory. In this study, we are set to investigate the structural, electronic, and magnetic properties of the frustrated Feᴵᴵ/Smⱽᴵ sublattice in relation to the widely studied perovskites for spintronics applications. The atomic composition, microstructure, crystallography, magnetization, thermal, and dielectric properties of a pyrochlore Sm₂Fe₂O₇ system synthesized using sol-gel methods are currently being investigated. Precursor powders were dissolved in citric acid monohydrate to obtain a solution. The obtained solution was stirred and heated using a magnetic stirrer to obtain the gel phase. Then, the gel was dried at 200°C to remove water and organic compounds and form an orange powder. The X-ray diffraction analysis confirms that the structure crystallized as a pyrochlore structure with a tetragonal F4mm (107) symmetry. The presence of Fe³⁺/Fe⁴⁺ mixed states is also revealed by XPS analysis.

Keywords: nanostructures, multiferroic materials, pyrochlores, spintronics

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Authors: Carlos Alberto Riveros, Edwin Fabián García, Javier Enrique Rivero

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The measured data obtained from sensors in continuous monitoring of civil structures are mainly used for modal identification and damage detection. Therefore when modal identification analysis is carried out the quality in the identification of the modes will highly influence the damage detection results. It is also widely recognized that the usefulness of the measured data used for modal identification and damage detection is significantly influenced by the number and locations of sensors. The objective of this study is the numerical implementation of two widely known optimum sensor placement methods in beam-like structures

Keywords: optimum sensor placement, structural damage detection, modal identification, beam-like structures.

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Authors: Thanh N. Do

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This paper addresses the modeling of two critical behaviors of concrete material in reinforced concrete components: (1) the increase in strength and ductility due to confining stresses from surrounding transverse steel reinforcements, and (2) the progressive deterioration in strength and stiffness due to high strain and/or cyclic loading. To improve the state-of-the-art, the author presents a new 3D constitutive model of concrete material based on plasticity and continuum damage mechanics theory to simulate both the confinement effect and the strength deterioration in reinforced concrete components. The model defines a yield function of the stress invariants and a compressive damage threshold based on the level of confining stresses to automatically capture the increase in strength and ductility when subjected to high compressive stresses. The model introduces two damage variables to describe the strength and stiffness deterioration under tensile and compressive stress states. The damage formulation characterizes well the degrading behavior of concrete material, including the nonsymmetric strength softening in tension and compression, as well as the progressive strength and stiffness degradation under primary and follower load cycles. The proposed damage model is implemented in a general purpose finite element analysis program allowing an extensive set of numerical simulations to assess its ability to capture the confinement effect and the degradation of the load-carrying capacity and stiffness of structural elements. It is validated against a collection of experimental data of the hysteretic behavior of reinforced concrete columns and shear walls under different load histories. These correlation studies demonstrate the ability of the model to describe vastly different hysteretic behaviors with a relatively consistent set of parameters. The model shows excellent consistency in response determination with very good accuracy. Its numerical robustness and computational efficiency are also very good and will be further assessed with large-scale simulations of structural systems.

Keywords: concrete, damage-plasticity, shear wall, confinement

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Authors: P. Chantarawitoon, H. Askarinejad

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The steel beams with web opening including the cellular and castellated I-beams are fabricated from a solid web I-beam through a double cutting method to a specific shape and size along the beam. The two halves of the beams are then welded together, increasing the overall depth of the web section. In this paper, the deflection of the cellular and castellated beams subject to uniform vertical loads are investigated using Finite Element Autodesk simulation package. The structural response of the beams with web opening are compared with regular solid beams. Additionally, parametric studies are carried out to study the influence of the geometric properties of a cellular beam to its structural responses.

Keywords: beams with web opening, cellular and castellated beams, finite element analysis, vertical deflection

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Authors: Raghda El-Nagara, Maher I. Nessim, Carmen E. Elshafee, Renee I. Abdallah, Yasser M. Moustafa

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Three asymmetric dicationic ionic liquids (ADILs), 1-(2-(1-dodecyl-2-methyl-1H-imidazolium-3-yl)ethyl)-3-methyl pyridinium bromide (IL₁), 1-(6-(1-dodecyl-2-methyl-1H-imidazolium-3-yl)hexyl)-3-methyl pyridinium bromide (IL₂) and 1-(10-(1-dodecyl-2-methyl-1H-imidazolium-3-yl)decyl)-3-methyl pyridinium bromide (IL₃) were synthesized with yield of 83.54, 84.12 & 83.05% respectively. They were elucidated via conventional tools of analysis (elemental analysis, FT-IR, and 1H-NMR). The thermogravimetric analysis confirmed that the three ADILs possessed high thermal stability (up to 500ᵒC). Their critical micelle concentration (CMC) was investigated and exhibited values of 5.5-1*10⁻³ Mol./L. They were evaluated as oil spill dispersants were at different temperatures (10, 30 & 50ᵒC) with different concentrations (750, 1500, 2000, 3000 ppm). Data reveals that the efficiency is ranked as follows: IL₂ > IL₁ > IL₃, which showed high dispersion efficiency reached to 63% with the concentration of 1500 ppm.

Keywords: ionic liquids, amphiphilic, oil spill dispersants, dicationic, efficiency test

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Authors: L. K. Davis

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The effects of the evolution force are observable in nature at all structural levels ranging from small molecular systems to conversely enormous biospheric systems. However, the evolution force and work associated with formation of biological structures has yet to be described mathematically or theoretically. In addressing the conundrum, we consider evolution from a unique perspective and in doing so we introduce the “Fundamental Theory of the Evolution Force: FTEF”. We utilized synthetic evolution artificial intelligence (SYN-AI) to identify genomic building blocks and to engineer 14-3-3 ζ docking proteins by transforming gene sequences into time-based DNA codes derived from protein hierarchical structural levels. The aforementioned served as templates for random DNA hybridizations and genetic assembly. The application of hierarchical DNA codes allowed us to fast forward evolution, while dampening the effect of point mutations. Natural selection was performed at each hierarchical structural level and mutations screened using Blosum 80 mutation frequency-based algorithms. Notably, SYN-AI engineered a set of three architecturally conserved docking proteins that retained motion and vibrational dynamics of native Bos taurus 14-3-3 ζ.

Keywords: 14-3-3 docking genes, synthetic protein design, time-based DNA codes, writing DNA code from scratch

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Authors: Mamdouh Y. Saleh, Gaber El Enany, Medhat H. Elzahar, Moustafa H. Omran

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The discharge limits of industrial waste water effluents are subjected to regulations which are getting more restricted with time. A former research occurred in Port Said city studied the efficiency of treating industrial wastewater using the first stage (A-stage) of the multiple-stage plant (AB-system).From the results of this former research, the effluent treated wastewater has high rates of total dissolved solids (TDS) and chemical oxygen demand (COD). The purpose of this paper is to improve the treatment process in removing TDS and COD. Thus, a pilot plant was constructed at wastewater pump station in the industrial area in the south of Port Said. Experimental work was divided into several groups adding activated carbon with different dosages to waste water, and for each group waste water was filtered after being mixed with activated carbon. pH and TSS as variables were also studied. At the end of this paper, a comparison was made between the efficiency of using activated carbon and the efficiency of using limestone in the same circumstances.

Keywords: adsorption, COD removal, filtration, TDS removal

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Authors: Jordan Fallow

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Service and advocacy organisations that serve refugee populations are often staffed by a large percentage of former refugees themselves, and this carries a number of implications for refugee rights, specifically economic and social rights. This paper makes an argument for the importance of introducing an understanding of intersectionality theory into organizations who provide services to and employ, refugee staff. The benefits of this are threefold; on an individual level it reduces the risks of burn out, vicarious trauma and compassion fatigue while increasing employee satisfaction and development, at an organizational level services become more effective, and at a systems level it helps reduce structural violence, which may itself have been a contributing factor in the movement of refugee staff from their origin countries. In support of this argument, a case study of an Australian settlement services organization is provided. Mixed methods research, utilising both qualitative and quantitative data, measured the perceived efficacy of diversity management tools at the organization and the impact this had on staff performance, retention and wellbeing. The paper also draws on strategic human resource and reward management, diversity management, international development and intersectionality texts.

Keywords: structural violence, employment, human resource management, intersectionality

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Authors: Abdulmagid A. Khattabi, Abdul Fatah M. Emhamed

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The steel alloy Introduced after becoming carbon-steel does not meet the requirements of engineering industry; and it cannot be obtained tensile strength from carbon-steel higher than (700MPa), the low alloy steel enters in a lot of heavy engineering equipment parts, molds, agricultural equipment and other industry. In addition, that may be exposed to in-service failure, which may require returned to work, to do the repairs or maintenance by one of the welding methods available. The ability of steel weld determined through palpation of the cracks, which can reduce by many ways. These ways are often expensive and difficult to implement, perhaps the control to choose the type of electrode welding user is one of the easiest and least expensive applications. It has been welding the steel low alloys high resistance by manual metal arc (MMA), and by using a set of welding electrodes which varying in chemical composition and in their prices as well and test their effect on tensile strength. Results showed that using the poles of welding, which have a high proportion of iron powder and low hydrogen. The Tensile resistance is (484MPa) and the weld joint efficiency was (56.9%), but when (OK 47.04) electrode was used the tensile strength increased to (720MPa) and the weld joint efficiency to (84.7%). Using the cheapest electrode (OK 45.00) the weld joint efficiency did not exceed (24.2%), but when using the most expensive electrode (OK 91.28) the weld joint efficiency is (38.1%).

Keywords: steel low alloys high resistance, electrodes welding, tensile test

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Authors: Vesta Kohlmeier, George C. Dragan, Juergen Orasche, Juergen Schnelle-Kreis, Dietmar Breuer, Ralf Zimmermann

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Aerosols from hazardous semi-volatile organic compounds (SVOC) may occur in workplace air and can simultaneously be found as particle and gas phase. For health risk assessment, it is necessary to collect particles and gases separately. This can be achieved by using a denuder for the gas phase collection, combined with a filter and an adsorber for particle collection. The study focused on the suitability of carbonaceous monolithic multi-channel denuders, so-called Novacarb™-Denuders (MastCarbon International Ltd., Guilford, UK), to achieve gas-particle separation. Particle transmission efficiency experiments were performed with polystyrene latex (PSL) particles (size range 0.51-3 µm), while the time dependent gas phase collection efficiency was analysed for polar and nonpolar SVOC (mass concentrations 7-10 mg/m3) over 2 h at 5 or 10 l/min. The experimental gas phase collection efficiency was also compared with theoretical predictions. For n-hexadecane (C16), the gas phase collection efficiency was max. 91 % for one denuder and max. 98 % for two denuders, while for diethylene glycol (DEG), a maximal gas phase collection efficiency of 93 % for one denuder and 97 % for two denuders was observed. At 5 l/min higher gas phase collection efficiencies were achieved than at 10 l/min. The deviations between the theoretical and experimental gas phase collection efficiencies were up to 5 % for C16 and 23 % for DEG. Since the theoretical efficiency depends on the geometric shape and length of the denuder, flow rate and diffusion coefficients of the tested substances, the obtained values define an upper limit which could be reached. Regarding the particle transmission through the denuders, the use of one denuder showed transmission efficiencies around 98 % for 1-3 µm particle diameters. The use of three denuders resulted in transmission efficiencies from 93-97 % for the same particle sizes. In summary, NovaCarb™-Denuders are well applicable for sampling aerosols of polar/nonpolar substances with particle diameters ≤3 µm and flow rates of 5 l/min or lower. These properties and their compact size make them suitable for use in personal aerosol samplers. This work is supported by the German Social Accident Insurance (DGUV), research contract FP371.

Keywords: gas phase collection efficiency, particle transmission, personal aerosol sampler, SVOC

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Authors: M. Nuhu, S. Bilal, A. A. Hamisu, J. A. Abbas, Y. Z. Aminu, P. O. Helen

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Exergy and energy analysis of preheating unit of FCCU of KRPC has been calculated and presented in this study. From the design, the efficiency of each heat exchanger was 86%. However, on completion of this work the efficiencies was calculated to be 39.90%, 55.66%, 56.22%, and 57.14% for 16E02, 16E03, 16E04, and 16E05 respectively. 16E04 has the minimum energy loss of 0.86%. The calculated second law and exergy efficiencies of the system were 43.01 and 56.99% respectively.

Keywords: exergy analysis, ideal work, efficiency, exergy destruction, temperature

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Authors: Ruqaya H. Aljabery

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Reinforced Concrete (RC) deep beams are one of the main critical structural elements in terms of safety since significant loads are carried in a short span. The shear capacity of these sections cannot be predicted accurately by the current design codes like ACI and EC2; thus, they must be investigated. In this research, non-linear behavior of RC deep beams strengthened in shear with Fiber Reinforced Polymer (FRP) strips, and the efficiency of FRP in terms of enhancing the shear capacity in RC deep beams are examined using Finite Element Analysis (FEA), which is conducted using the software ABAQUS. The effect of several parameters on the shear capacity of the RC deep beam are studied in this paper as well including the effect of the cross-sectional area of the FRP strip and the shear reinforcement area to the spacing ratio (As/S), and it was found that FRP enhances the shear capacity significantly and can be a substitution of steel stirrups resulting in a more economical design.

Keywords: Abaqus, concrete, deep beam, finite element analysis, FRP, shear strengthening, strut-and-tie

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Authors: Taher S. Ababneh, Taghreed M. A. Jazzazi, Tareq M. A. Alshboul

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The inhibiting action against aluminum corrosion by three derivatives of 1,8-bis (benzylideneamino) naphthalene (BN) Schiff base has been investigated by means of DFT quantum chemical calculations at the B3LYP/6-31G(d) level of theory. The derivatives (CBN, NBN and MBN) were prepared from the condensation reaction of 1,8-diaminonaphthalene with substituted benzaldehyde (4-CN, 3-NO₂ and 3,4-(OMe)₂, respectively). Calculations were conducted to study the adsorption of each Schiff base on aluminum surface to evaluate its potential as a corrosion inhibitor. The computational structural features and electronic properties of each derivative such as relative energies and energies of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) have been reported. Thermodynamic functions and quantum chemical parameters such as the hardness of the inhibitor, the softness and the electrophilicity index were calculated to determine the derivative of the highest inhibition efficiency.

Keywords: corrosion, aluminum, DFT calculation, 1, 8-diaminonaphthalene, benzaldehyde

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Authors: Thapelo Aubrey Motsieng

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Fluidized bed combustion (FBC) is a clean coal technology used in the combustion of low-grade coals for power generation. The production of large solid wastes such as bottom ashes from this process is a problem. The bottom ash contains some toxic elements which can leach out soils and contaminate surface and ground water; for this reason, they can neither be disposed of in landfills nor lagoons anymore. The production of geopolymers from bottom ash for structural and concrete applications is an option for their disposal. In this study, the waste bottom ash obtained from the combustion of three low grade South African coals in a bubbling fluidized bed reactor was used to produce geopolymers. The geopolymers were cured in a household microwave. The results showed that the microwave curing enhanced the reactivity and strength of the geopolymers.

Keywords: bottom ash, geopolymers, coal, compressive strength

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Authors: Dinesha Siriwardhane, Indralal De Silva, Sampath Amaratunge

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Objective of this study is to explore the recent trends, patterns and the structural changes in the labour migration from Sri Lanka to Middle East countries and to discuss the possible impacts of those changes on the remittance flow. Study uses secondary data published by Sri Lanka Bureau of Foreign Employment and Central Bank. Thematic analysis of the secondary data revealed that the migration for labour has increased rapidly during past decades. Parallel with that the gender and the skill composition of the migration flow has been changing. Similarly, the destinations for male migration have changed over the period. These show positive implications on the international remittance receipts to the country.

Keywords: migration, middle east, Sri Lanka, social sciences

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Authors: Mehmet Akköse

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In ground motions recorded in recent major earthquakes such as 1994 Northridge earthquake in US, 1995 Kobe earthquake in Japan, 1999 Chi-Chi earthquake in Taiwan, and 1999 Kocaeli earthquake in Turkey, it is noticed that they have large velocity pulses. The ground motions with the velocity pulses recorded in the vicinity of an earthquake fault are quite different from the usual far-fault earthquake ground motions. The velocity pulse duration in the near-fault ground motions is larger than 1.0 sec. In addition, the ratio of the peak ground velocity (PGV) to the peak ground acceleration (PGA) of the near-fault ground motions is larger than 0.1 sec. The ground motions having these characteristics expose the structure to high input energy in the beginning of the earthquake and cause large structural responses. Therefore, structural response to near-fault ground motions has received much attention in recent years. Interactions between neighboring, inadequately separated buildings have been repeatedly observed during earthquakes. This phenomenon often referred to as earthquake-induced structural pounding, may result in substantial damage or even total destruction of colliding structures during strong ground motions. This study focuses on effects of near-fault ground motions on earthquake-induced pounding response of RC buildings. The program SAP2000 is employed in the response calculations. The results obtained from the pounding analyses for near-fault and far-fault ground motions are compared with each other.

Keywords: near-fault ground motion, pounding analysis, RC buildings, SAP2000

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Authors: Hikmet Cicek

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Metal nitrides show excellence tribological properties and they used for especially on machine parts. In this work, the vacuum gas nitriding proses were applied to the titanium, D2 and 52100 steel substrates at three different proses temperatures (500 °C, 600°C and 700 °C). Structural, mechanical and tribological properties of the samples were characterized. X-Ray diffractometer, scanning electron microscope and energy dispersive spectroscopy analyses were conducted to determine structural properties. Microhardness test and pin-on-disc wear test were made to observe tribological properties. Coefficient of friction, wear rate and wear traces were examined comparatively. According to the test results, the process temperature very effective parameter for the vacuum gas nitriding method.

Keywords: gas nitriding, tribology, wear, coating

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Authors: Krishnamoorthy Sathiyan, Shanti Gopal Patra, Ronen Bar-Ziv, Tomer Zidki

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Developing efficient non-noble metal catalysts that are cheap and durable for oxygen evolution reaction (OER) is a great challenge. Moreover, altering the electronic structure of the catalyst and structural engineering of the materials provide a new direction for enhancing the OER. Herein, we have successfully synthesized Fe and Co incorporated MoS₂ catalysts, which show improved catalytic activity for OER when compared with MoS₂, Fe-MoS₂, and Co-MoS₂. It was found that at an optimal ratio of Fe and Co, the electronic and structural modification of MoS₂ occurs, which leads to change in orientation and thereby enhances the active catalytic sites on the edges, which are more exposed for OER. The nanocomposites have been well characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and energy dispersive X-ray analysis (EDX), Elemental Mapping, transmission electron microscope (TEM), and high-resolution transmission electron microscope (HR-TEM) analysis. Among all, a particular ratio of FeCo-MoS₂ exhibits a much smaller onset with better catalytic current density. The remarkable catalytic activity is mainly attributed to the synergistic effect from the Fe and Co. Most importantly, our work provides an essential insight in altering the electronic structure of MoS₂ based materials by incorporating promoters such as Co and Fe in an optimal amount, which enhances OER activity.

Keywords: electrocatalysts, molybdenum disulfide, oxygen evolution reaction, transition metals

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Authors: Ahmed Shaban Abdel Hay Gabr

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Water hyacinth (W-H) has an adverse effect on Nile river in Egypt, it absorbs high quantities of water, it needs to serve these quantities especially at this time, so by burning W-H, it can be used in concrete mix to reduce the permeability of concrete and increase both the compressive and splitting strength. The effect of W-H on non-structural concrete properties was studied, but there is a lack of studies about the behavior of structural concrete containing W-H. Therefore, in the present study, the behavior of 15 RC beams with 100 x 150 mm cross section, 1250 mm span, different reinforcement ratios and different W-H ratios were studied by testing the beams under two-point bending test. The test results showed that Water Hyacinth is compatible with RC which yields promising results.

Keywords: beams, reinforcement ratio, reinforced concrete, water hyacinth

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Authors: Yeliz Ekinci, Raife Merve Ön

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Nowadays, technological progress is one of the most important components of economic growth and the efficiency of R&D activities is particularly essential for countries. This study is an attempt to analyze the R&D efficiencies of EU countries. The indicators related to R&D efficiencies should be determined in advance in order to use DEA. For this reason a list of input and output indicators are derived from the literature review. Considering the data availability, a final list is given for the numerical analysis for future research.

Keywords: data envelopment analysis, economic growth, EU countries, R&D efficiency

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Authors: Chin-Shan Lu, Yi-Pei Liu

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This study examines the factors influencing the adoption of MASS in Taiwan's shipping industry. Digital technology and unmanned vehicle advancements have enhanced efficiency and reduced environmental impact in the shipping industry. The IMO has set regulations to promote low-carbon emissions and autonomous ship technology. Using the TOE framework and DOI theory, a research model was constructed, and data from 132 Taiwanese shipping companies were collected via a questionnaire survey. A structural equation modeling (SEM) was conducted to examine the relationships between variables. Results show that technological and environmental factors significantly influence operators' attitudes toward MASS, while organizational factors impact their willingness to adopt. Enhancing technological support, internal resource allocation, top management support, and cost management are crucial for promoting adoption. This study identifies key factors and provides recommendations for adopting autonomous ships in Taiwan's shipping industry.

Keywords: MASS, technology-organization-environment, diffusion of innovations theory, shipping industry

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Authors: A. Mekroud, A. Khemis, M. S. Mecibah

Abstract:

The tribological behavior of a pin of paramagnetic material (aluminum), rolling on a rotating disk made of ferromagnetic material (steel XC48) in the presence of an externally applied alternating magnetic field, with the passage of electric current were studied. All tests were performed using a conventional tribometer pin- disk. Structural characterization of the surfaces in contact, oxides and wear debris, by X-ray diffraction (θ-2θ angle), showed the significant effect of magnetic field on the activation of the contact surface of the pin in no ferromagnetic material. The absence of the magnetic field causes a change of wear mode.

Keywords: structural characterization of the surfaces, oxides and wear debris, X-ray diffraction

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