Search results for: beam division multiple access

Authors: N. Larbi, F. Debbat

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Wireless communication systems have changed dramatically and shown spectacular evolution over the past two decades. These radio technologies are engaged in a quest endless high-speed transmission coupled to a constant need to improve transmission quality. Various radio communication systems being developed use code division multiple access (CDMA) technique. This work analyses a hybrid honey bees mating optimization algorithm (HBMO) applied to multiuser detection (MuD) in CDMA communication systems. The HBMO is a swarm-based optimization algorithm, which simulates the mating process of real honey bees. We apply a hybridization of HBMO with simulated annealing (SA) in order to improve the solution generated by the HBMO. Simulation results show that the detection based on Hybrid HBMO, in term of bit error rate (BER), is viable option when compared with the classic detectors from literature under Rayleigh flat fading channel.

Keywords: BER, DS-CDMA multiuser detection, genetic algorithm, hybrid HBMO, simulated annealing

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Authors: Winfred Okoe Addy, Jean Jacques Dominique Beraud

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Access control systems (ACs) are some of the most important components in safety areas. Inaccuracies of regulatory frameworks make personal policies and remedies more appropriate than standard models or protocols. This problem is exacerbated by the increasing complexity of software, such as integrated Big Data (BD) software for controlling large volumes of encrypted data and resources embedded in a dedicated BD production system. This paper proposes a general access control strategy system for the diffusion of Big Data domains since it is crucial to secure the data provided to data consumers (DC). We presented a general access control circulation strategy for the Big Data domain by describing the benefit of using designated access control for BD units and performance and taking into consideration the need for BD and AC system. We then presented a generic of Big Data access control system to improve the dissemination of Big Data.

Keywords: access control, security, Big Data, domain

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Authors: Mustafa Kaya

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After the 1999 Marmara earthquake in Turkey research by the Turkish Precast Union stated that 24.50% of the precast structures were damaged with some of this damage being observed in the beam to column connections of the structures. Since it is essential to provide those rendered homeless by the earthquake with safe, habitable accommodation repairing medium and slight levels of damage at the connection parts should be undertaken. In order to prove that a repaired connection was sufficiently strong, a precast beam to column post tensioned connection was tested in three phases. In phase one, the middle level damage was observed at 6% drift at these connections. As a result of the extra loads applied, little damage was observed. In the last phase, the four connections tested in the first phase were repaired using epoxy resin and then retested. The results from the tests on the repaired precast and the undamaged specimens showed that the repaired specimens were sufficiently strong, thus proving that repair to damaged precast beam to column post tensioned connections can be undertaken.

Keywords: precast beam to column connection, moment-resisting connection, post-tensioned connections, repair of precast connections

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Authors: Kwame Kodua-Ntim

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The study explored the authors self-archiving to create awareness of open-access institutional repositories in universities. The qualitative approach of the study was informed by the interpretive paradigm as well as the case research design. The target population for the study was all twelve (12) open-access institutional repositories managers and administrators purposively selected from the five (5) universities in Ghana. The universities were chosen since they were the only ones listed in the Directory of Open Access Repositories. Interviews were conducted using a semi-structured interview guide and data were analyzed using thematic analysis. The study revealed that academics had some information about self-archiving in open-access institutional repositories and university libraries with open-access institutional repositories were using DSpace software. Managers and administrators of open-access institutional repositories mediated content uploaded and believed that author self-archiving could improve awareness of open-access institutional repositories. The study recommended that universities should fully implement the author’s self-archiving protocol, and academics should be trained to be able to upload research works onto open-access institutional repositories. Furthermore, the university and university library should provide rigorous policies on author self-archiving and incentives for author self-archiving in the open access institutional repositories.

Keywords: author, awareness, institutional repositories, open access, open archive, self-archiving

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Authors: Gholamreza Koochaki

Abstract:

This paper presents the buckling analysis of functionally graded beams with various boundary conditions. The first order shear deformation beam theory (Timoshenko beam theory) and the classical theory (Euler-Bernoulli beam theory) of Reddy have been applied to the functionally graded beams buckling analysis The material property gradient is assumed to be in thickness direction. The equilibrium and stability equations are derived using the total potential energy equations, classical theory and first order shear deformation theory assumption. The temperature difference and applied voltage are assumed to be constant. The critical buckling temperature of FG beams are upper than the isotropic ones. Also, the critical temperature is different for various boundary conditions.

Keywords: buckling, functionally graded beams, Hamilton's principle, Euler-Bernoulli beam

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Authors: Abdulkadir Cuneyt Aydin, Mahyar Maali, Mahmut Kılıç, Merve Sağıroğlu

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The moment-rotation curves of semi-rigid connections are the visual expressions of the actual behaviour discovered in beam-to-column connections experiments. This research was to determine the behaviour of the connection using full-scale experiments under statically loaded. The stiffeners which are typically attached to beams web or flanges to control local buckling and to increase shear capacity in a beam web are almost always used in modern designs. They must also provide sufficient moment of inertia to control out of plane deformations. This study was undertaken to analyse the influence of stiffeners in the angles and beams on the behaviour of the beam-to-column joints. In addition, the aim was to provide necessary data to improve the Eurocode 3. The main parameters observed are the evolution of the resistance, the stiffness, the rotation capacity, the ductility of a joint and the Energy Dissipation. Experimental tests show that the plastic flexural resistance and the energy dissipation increased when thickness of stiffener beam, thickness of stiffener angles were increased in the test specimens. And also, while stiffness of joints, the bending moment capacity and the maximum bending moment increased with the increasing thickness of stiffener beam, these values decreased with the increasing thickness of stiffener angles. So, it is observed that the beam stiffener of angles are important in improving resistance moment of beam-to-column semi-rigid joints.

Keywords: bolted angles connection, semi-rigid joints, ductility of a joint, angles and beams stiffeners

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Authors: Veronika Přivřelová

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Well-designed composite steel and concrete structures highlight the good material properties and lower the deficiencies of steel and concrete, in particular they make use of high tensile strength of steel and high stiffness of concrete. The most common composite steel and concrete structure is a simply supported beam, which concrete slab transferring the slab load to a beam is connected to the steel cross-section. The aim of this paper is to find the most adequate numerical model of a simply supported composite beam with the cross-sectional and material parameters based on the results of a processed parametric study and numerical analysis. The paper also evaluates the suitability of using compact concrete with the lightweight aggregates for composite steel and concrete beams. The most adequate numerical model will be used in the resent future to compare the results of laboratory tests.

Keywords: composite beams, high-performance concrete, high-strength steel, lightweight concrete slab, modeling

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Authors: Facundo L. Vasconsellos, Erwin

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In building construction, the use of web opening as a passage for service pipes is very common with the main purpose of space saving. The strength of the beam may be reduced by this opening, and thus, the configuration of the web opening should be well-designed. A design guide to aid the design of the beam with web opening is available, but it was established based on studies on the beam subjected to gravity-type loading. In simple words, there are no clear design guidelines for the design of beams with web openings subjected to seismic-type loading, which is required in Taiwan. Without any clear guidelines, engineers tend to design the web opening based on their experience, and in most cases, the design is too conservative. A massive amount of reinforcement is sometimes required even though the opening is introduced to the web in low-stress regions. The cost of the reinforcement is usually high. In view of the current situation, there exists a need to investigate the seismic behavior of beams subjected to seismic-type loading so that practical solutions can be provided to aid the engineer in designing the beams with web openings. The current study focuses on investigating the seismic behavior of beams with unreinforced web openings subjected to seismic-type loading. As the preliminary study, the scope of the study is limited to the beam that is only subjected to uniformly distributed gravity load before being subjected to seismic-type loading. The main objective of this study is to confirm that there exists a chance for introducing a web opening without any reinforcement on a beam subjected to seismic-type loading. Three beams, one without and two with circular web openings, were tested to observe how web openings will affect the beam performance under seismic load. The test result shows that for the beam section and length tested in this study, the presence of the web opening located relatively close to the beam plastic hinge region did not affect the overall performance of the beam. No distinct difference in hysteretic behavior can be observed between the beams with and without web opening. The chance of introducing unreinforced web openings on beams designed as highly ductile members exists. Following the test, numerical simulation was also conducted to investigate the hysteretic behavior of various dimensions of beams with one large unreinforced circular web opening. As a result, a design recommendation is proposed to aid the engineer in judging whether the opening reinforcement is required or not. Without reinforcement, considerable cost savings can be achieved.

Keywords: circular web opening, seismic design, steel beam design, unreinforced web opening

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Authors: Veerpaul Maan, Gaurav Mishra

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The evolution of omnichannel has revolutionized the supply chain of the organizations by enhancing customer shopping experience. For these organizations need to develop well-integrated multiple distribution channels to leverage the benefits of omnichannel. To adopt an omnichannel system in the supply chain has resulted in structuring and reconfiguring the practices of the traditional supply chain distribution network. In this paper a multiple distribution supply chain network (MDSCN) have been proposed which integrates online giants with a local retailers distribution network in uncertain environment followed by sustainability. To incorporate sustainability, an additional objective function is added to reduce the carbon content through minimizing the travel distance of the product. Through this proposed model, customers are free to access product and services as per their choice of channels which increases their convenience, reach and satisfaction. Further, a numerical illustration is being shown along with interpretation of results to validate the proposed model.

Keywords: sustainable supply chain network, omnichannel, multiple distribution supply chain network, integrate multiple distribution channels

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Authors: Raja Rajeswari K

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Orthogonal Frequency Division Multiplexing (OFDM), a multi Carrier transmission technique that has been used in implementing the majority of wireless applications like Wireless Network Protocol Standards (like IEEE 802.11a, IEEE 802.11n), in telecommunications (like LTE, LTE-Advanced) and also in Digital Audio & Video Broadcast standards. The latest research and development in the area of orthogonal frequency division multiplexing, Universal Filtered Multi Carrier (UFMC) & Filtered OFDM (F-OFDM) has attracted lots of attention for wideband wireless communications. In this paper UFMC & F-OFDM system are implemented and comparative analysis are carried out in terms of M-ary QAM modulation scheme over Dolph-chebyshev filter & rectangular window filter and to estimate Bit Error Rate (BER) over Rayleigh fading channel.

Keywords: UFMC, F-OFDM, BER, M-ary QAM

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Authors: Chidiebere Joy Nwankwo, Benjamin S. C. Uzochukwu, Florence T. Sibeudu

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Background: Family planning is one of the most cost-effective ways to prevent maternal, infant, and child mortality. It can decrease maternal mortality by reducing the number of unintended pregnancies, the number of abortions, and the proportion of births at high risk. It has been seen to improve the health and economic well-being of families and communities and ensures women’s planned childbearing in order to achieve education and career goals which could raise family income thereby reducing poverty. The choice and use of a particular family planning method and their sources vary globally. Rural Communities often face significant challenges in accessing and utilizing family planning services. Aim: This study set out to assess Access and Utilization of Family Planning Services among Women of Reproductive Age in a Rural Community of Enugu state, Nigeria. Rural communities were chosen for this study because past demographic surveys have shown that women in urban areas are more likely to accept and practice family planning compared to those in rural areas. Method: A Descriptive Cross-sectional Research design was employed to achieve the aim and objectives of the study. Data collected from 177 consenting participants using interviewer-administered questionnaires was analysed using Descriptive statistics to summarize the Socio-demographic characteristics of the participants and Access and Utilization of Family Planning Services among the participants including Reasons for using different Family Planning Methods and Barriers encountered in Access and Utilization of these services. A Cross-tabulation between Socio-demographic Characteristics of respondents and the use of Family Planning services was carried out. Result: The findings of this study revealed that majority of the participants (72.9%) have not utilized any family planning service. Out of those (27.1%) that have used any family planning service, majority of them are still currently using a form of family planning service and have access to them in health facilities, patent medicine vendors and others based on multiple responses. Male condoms were the most utilized modern family planning service. Based on multiple responses, inaccessibility, personal beliefs and partner’s objection were the most identified barriers encountered in accessing family planning services. Conclusion: Access and uptake of family planning services in rural communities is lower than the national average. Increasing access to family planning is an urgent priority for rural areas Interventions that will scale up Access and Utilization of family planning services in rural communities should be intensified.

Keywords: access, family planning, rural community, utilization

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Authors: Muhammad Sameer Ahmed, Piotr Remlein, Tansal Gucluoglu

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The technique called as Generalized frequency division multiplexing (GFDM) used in the free space optical channel can be a good option for implementation free space optical communication systems. This technique has several strengths e.g. good spectral efficiency, low peak-to-average power ratio (PAPR), adaptability and low co-channel interference. In this paper, the impact of weather conditions such as haze, rain and fog on GFDM over the gamma-gamma channel model is discussed. A Trade off between link distance and system performance under intense weather conditions is also analysed. The symbol error probability (SEP) of GFDM over the gamma-gamma turbulence channel is derived and verified with the computer simulations.

Keywords: free space optics, generalized frequency division multiplexing, weather conditions, gamma gamma distribution

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Authors: Carlos Joel Tchawouo Mbiada

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This paper intends to refrain from debating the different meanings of justice, such as its social or moral meaning, nor to discuss the different theories of justice. This paper focuses on the legal understanding of access to justice to mean access to the court. Using the Labour and Labour Appeal Courts as a case study, this paper investigates whether the composition of the bench, the personnel and state mechanisms to promote access to court offer ideal conditions to access to court. The investigation is benchmarked against the South African new constitutional order underpinned by the concept of social justice to eradicate past injustices. To provide justice to all, the Constitution of the Republic of South Africa 1996 guarantees the right to access to the court. The question that takes centre stage in this paper is whether litigants are denied the right to access the Labour and Labour Appeal Courts. The paper argues that factors such as the status of the Labour and Labour Appeal Courts, the number of judges, and the building structure prevent litigants from accessing these courts. The paper advocates for a legislative overhaul of the Labour and Labour Appeal Courts structure so that litigants may access the courts. Until such time, the paper argues that the right to access the Labour and Labour Appeal Courts would remain far from the reach of many litigants.

Keywords: access to justice, access to court, labour court, labour appeal court

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Authors: Ping Li, Bing Feng, Junpu Zhao, Xudong Xie, Dangpeng Xu, Kuixing Zheng, Qihua Zhu, Xiaofeng Wei

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In laser driven inertial confinement fusion (ICF), the control of the temporal shape of the laser pulse is a key point to ensure an optimal interaction of laser-target. One of the main difficulties in controlling the temporal shape is the foot part control accuracy of high contrast pulse. Based on the analysis of pulse perturbation in the process of amplification and frequency conversion in high power lasers, an approach of beam spatio-temporal multiplexing is proposed to improve the control precision of high contrast pulse. In the approach, the foot and peak part of high contrast pulse are controlled independently, which propagate separately in the near field, and combine together in the far field to form the required pulse shape. For high contrast pulse, the beam area ratio of the two parts is optimized, and then beam fluence and intensity of the foot part are increased, which brings great convenience to the control of pulse. Meanwhile, the near field distribution of the two parts is also carefully designed to make sure their F-numbers are the same, which is another important parameter for laser-target interaction. The integrated calculation results show that for a pulse with a contrast of up to 500, the deviation of foot part can be improved from 20% to 5% by using beam spatio-temporal multiplexing approach with beam area ratio of 1/20, which is almost the same as that of peak part. The research results are expected to bring a breakthrough in power balance of high power laser facility.

Keywords: inertial confinement fusion, laser pulse control, beam spatio-temporal multiplexing, power balance

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Authors: Monirah Alkathiry, Hanan Aljarwan

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Cloud computing is one of the most significant technologies that the world deals with, in different sectors with different purposes and capabilities. The cloud faces various challenges in securing data from unauthorized access or modification. Consequently, security risks and levels have greatly increased. Therefore, cloud service providers (CSPs) and users need secure mechanisms that ensure that data are kept secret and safe from any disclosures or exploits. For this reason, CSPs need a number of techniques and technologies to manage and secure access to the cloud services to achieve security goals, such as confidentiality, integrity, identity access management (IAM), etc. Therefore, this paper will review and explore various access controls implemented in a cloud environment that achieve different security purposes. The methodology followed in this survey was conducting an assessment, evaluation, and comparison between those access controls mechanisms and technologies based on different factors, such as the security goals it achieves, usability, and cost-effectiveness. This assessment resulted in the fact that the technology used in an access control affects the security goals it achieves as well as there is no one access control method that achieves all security goals. Consequently, such a comparison would help decision-makers to choose properly the access controls that meet their requirements.

Keywords: access controls, cloud computing, confidentiality, identity and access management

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Authors: G. Traini, G. Battistoni, F. Collamati, E. De Lucia, R. Faccini, C. Mancini-Terracciano, M. Marafini, I. Mattei, S. Muraro, A. Sarti, A. Sciubba, E. Solfaroli Camillocci, M. Toppi, S. M. Valle, C. Voena, V. Patera

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In Particle Therapy (PT) treatments a large amount of secondary particles, whose emission point is correlated to the dose released in the crossed tissues, is produced. The measurement of the secondary charged fragments component could represent a valid technique to monitor the beam range during the PT treatments, that is a still missing item in the clinical practice. A sub-millimetrical precision on the beam range measurement is required to significantly optimise the technique and to improve the treatment quality. In this contribution, a detector, named Dose Profiler (DP), is presented. It is specifically planned to monitor on-line the beam range exploiting the secondary charged particles produced in PT Carbon ions treatment. In particular, the DP is designed to track the secondary fragments emitted at large angles with respect to the beam direction (mainly protons), with the aim to reconstruct the spatial coordinates of the fragment emission point extrapolating the measured track toward the beam axis. The DP is currently under development within of the INSIDE collaboration (Innovative Solutions for In-beam Dosimetry in hadrontherapy). The tracker is made by six layers (20 × 20 cm²) of BCF-12 square scintillating fibres (500 μm) coupled to Silicon Photo-Multipliers, followed by two plastic scintillator layers of 6 mm thickness. A system of front-end boards based on FPGAs arranged around the detector provides the data acquisition. The detector characterization with cosmic rays is currently undergoing, and a data taking campaign with protons will take place in May 2017. The DP design and the performances measured with using MIPs and protons beam will be reviewed.

Keywords: fragmentation, monitoring, particle therapy, tracking

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Authors: Amandeep Singh Dhaliwal

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Networking solutions, particularly wireless local area networks have revolutionized the technological advancement. Wireless Local Area Networks (WLANs) have gained a lot of popularity as they provide location-independent network access between computing devices. There are a number of access methods used in Wireless Networks among which DCF and PCF are the fundamental access methods. This paper emphasizes on the impact of DCF and PCF access mechanisms on the performance of the IEEE 802.11a, 802.11b and 802.11g standards. On the basis of various parameters viz. throughput, delay, load etc performance is evaluated between these three standards using above mentioned access mechanisms. Analysis revealed a superior throughput performance with low delays for 802.11g standard as compared to 802.11 a/b standard using both DCF and PCF access methods.

Keywords: DCF, IEEE, PCF, WLAN

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Authors: S. H. Bae, D. W. Cho, W. B. Jeong, J. R. Cho

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Fatigue fracture of an aluminum welded structure is a phenomenon frequently occurring from pores in a weld. In order to grasp the state of the welded structure in operation in real time, the acceleration signal of the structure is measured. At this time, the vibration characteristic of the signal according to the fatigue load is an important parameter of the state diagnosis. This paper was an experimental study on the variation of vibration characteristics of welded beams with vibration aging (especially bending vibration). First simple beams were produced according to welding conditions. Each beam was vibrated and measured beam's PSD (power spectral density) according to the degree of aging. Also, modal testing was conducted to compare the transfer functions of welded beams. Testing result shows that the natural frequencies of the beam changed with the vibration aging due to the change of stiffness in welding part and its stiffness was estimated by the finite element method.

Keywords: modal testing, natural frequency, vibration aging, welded structure

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Authors: Mustafa Kaya

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In this study, the effect of pre-stressed strand diameters, providing the beam-to-column connections, was investigated from both experimental, and analytical aspects. In the experimental studies, the strength and stiffness, the capacities of the precast specimens were compared. The precast specimen with strands of 15.24 mm reached an equal strength of the reference specimen. Parallel results were obtained during the analytical studies from the aspects of strength, and behavior, but in terms of stiffness, it was seen that the initial stiffness of the analytical models was lower than that of the tested specimen.

Keywords: post-tensioned connections, beam to column connections, finite element method, strand diameter

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Authors: Abdulsamee Halahla, Emad Allout

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

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

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Authors: Samvel H. Sargsyan

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Together with the study of electron-optical properties of nanostructures and proceeding from experiment-based data, the study of the mechanical properties of nanostructures has become quite actual. For the study of the mechanical properties of fullerene, carbon nanotubes, graphene and other nanostructures one of the crucial issues is the construction of their adequate mathematical models. Among all mathematical models of graphene or carbon nano-tubes, this so-called discrete-continuous model is specifically important. It substitutes the interactions between atoms by elastic beams or springs. The present paper demonstrates the construction of the discrete-continual beam model for carbon nanotubes or graphene, where the micropolar beam model based on the theory of moment elasticity is accepted. With the account of the energy balance principle, the elastic moment constants for the beam model, expressed by the physical and geometrical parameters of carbon nanotube or graphene, are determined. By switching from discrete-continual beam model to the continual, the models of micropolar elastic cylindrical shell and micropolar elastic plate are confirmed as continual models for carbon nanotube and graphene respectively.

Keywords: carbon nanotube, discrete-continual, elastic, graphene, micropolar, plate, shell

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Authors: Bukhari Badamasi, Chidi G. Ononiwu

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Globally, educational technology (EdTech) has become a known catalyst for gaining access to education, job creation, and national development of a nation. Howbeit, it is common understanding that higher institutions continue to deploy digital technologies, to help provide access to education, but in most case, it is somehow institutional access not epistemological access especially in sub Saharan African higher institutions. Some scholars, however, lament the fact that studies on educational technology affordances are mostly fragmented because they focus on specific theme or sub aspect of access (i.e., institutional access). Thus, drawing from the Archer Morphogenetic approach, and Gibson Affordance theory, and applying critical realist based Danermark model for explanatory research, the study seeks to conduct a realist case study on underprivileged students in Higher institutions on how they gain epistemological access by enacting educational technology (EdTech) affordances.

Keywords: affordance, epistemological access, educational technology, underprivileged students

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Authors: H. M. Alfrihidi, H.A. Albarakaty

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Flattening filter-free (FFF) photon beam radiotherapy has increased in the last decade, which is enabled by advancements in treatment planning systems and radiation delivery techniques like multi-leave collimators. FFF beams have higher dose rates, which reduces treatment time. On the other hand, FFF beams have a higher surface dose, which is due to the loss of beam hardening effect caused by the presence of the flatting filter (FF). The possibility of improving FFF beam quality using filters from low-z materials such as steel and aluminium (Al) was investigated using Monte Carlo (MC) simulations. The attenuation coefficient of low-z materials for low-energy photons is higher than that of high-energy photons, which leads to the hardening of the FFF beam and, consequently, a reduction in the surface dose. BEAMnrc user code, based on Electron Gamma Shower (EGSnrc) MC code, is used to simulate the beam of a 6 MV True-Beam linac. A phase-space (phosphor) file provided by Varian Medical Systems was used as a radiation source in the simulation. This phosphor file was scored just above the jaws at 27.88 cm from the target. The linac from the jaw downward was constructed, and radiation passing was simulated and scored at 100 cm from the target. To study the effect of low-z filters, steel and Al filters with a thickness of 1 cm were added below the jaws, and the phosphor file was scored at 100 cm from the target. For comparison, the FF beam was simulated using a similar setup. (BEAM Data Processor (BEAMdp) is used to analyse the energy spectrum in the phosphorus files. Then, the dose distribution resulting from these beams was simulated in a homogeneous water phantom using DOSXYZnrc. The dose profile was evaluated according to the surface dose, the lateral dose distribution, and the percentage depth dose (PDD). The energy spectra of the beams show that the FFF beam is softer than the FF beam. The energy peaks for the FFF and FF beams are 0.525 MeV and 1.52 MeV, respectively. The FFF beam's energy peak becomes 1.1 MeV using a steel filter, while the Al filter does not affect the peak position. Steel and Al's filters reduced the surface dose by 5% and 1.7%, respectively. The dose at a depth of 10 cm (D10) rises by around 2% and 0.5% due to using a steel and Al filter, respectively. On the other hand, steel and Al filters reduce the dose rate of the FFF beam by 34% and 14%, respectively. However, their effect on the dose rate is less than that of the tungsten FF, which reduces the dose rate by about 60%. In conclusion, filters from low-z material decrease the surface dose and increase the D10 dose, allowing for a high-dose delivery to deep tumors with a low skin dose. Although using these filters affects the dose rate, this effect is much lower than the effect of the FF.

Keywords: flattening filter free, monte carlo, radiotherapy, surface dose

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Authors: Talebi Aliasghar, Ebrahimpour Komeleh Hooman, Maghsoudi Ali Akbar

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In reinforced concrete (RC) structures, beam-column connection region has a considerable effect on the behavior of structures. Using fiber reinforcement polymer (FRP) for the strengthening of connections in RC structures can be one of the solutions to retrofitting this zone which result in the enhanced behavior of structure. In this paper, these changes in behavior by using FRP for high strength concrete beam-column connection have been studied by finite element modeling. The concrete damage plasticity (CDP) model has been used to analyze the RC. The results illustrated a considerable development in load-bearing capacity but also a noticeable reduction in ductility. The study also assesses these qualities for several modes of strengthening and suggests the most effective mode of strengthening. Using FRP in flexural zone and FRP with 45-degree oriented fibers in shear zone of joint showed the most significant change in behavior.

Keywords: HSC, beam-column connection, Fiber Reinforcement Polymer, FRP, Finite Element Modeling, FEM

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Authors: Aissa Hanifi

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People across different world societies are using information and communication technology (ICT) for different purposes. Unfortunately, in contemporary societies, some people have little access to ICT and thus cannot have effective participation in society compared with those who have better access. The purpose of this study is to test the impact of ICTs on university life in general and students' performance in particular. The study relied on an online survey questionnaire that was administered to 30 undergraduate students at Chef University. The findings of the survey revealed that there is still an important number of students who do not have easy access to ICT. Such limited access to ICTs is attributed to varied factors. Some students live in rural areas, where due to the poor internet coverage, they face difficulties in competing with students who live in urban areas with better ICT access. The lack of ICT access has hindered the students' university performance in general and their language skills, and the exchange of information with teachers and classmates.

Keywords: access, communication, ICT, performance, technology

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Authors: Shuyuan Lin, Zhaohui Huang, Mizi Fan

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In the majority of previous research into modelling large scale composite floor subjected to fire, the beam-to-column and beam-to-beam connections were assumed to behave either as pinned or rigid for simplicity, and the vertical shear and axial tension failures of the connection were not taken into account. We have recently developed robust two-noded connection models for modeling endplate and partial endplate steel connections under fire conditions. The main objective of this research is to systematically investigate the impact of the connections of protected beams, on the tensile membrane actions of supported floor slabs in which the failures of the connections, such as, axial tension, vertical shear and bending are accounted for. The models developed have very good numerical stability under a static solver condition, and can be used for large scale modelling of composite buildings in fire.

Keywords: fire, steel structure, component-based model, beam-to-column connections

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Authors: Elmahdi Mohammadine, Ahouzi Esmail, Najid Abdellah

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This contribution aims to present a new protected hybrid WDM/TDM PON architecture using Wavelength Selective Switches and Optical Line Protection devices. The objective from using these technologies is to improve flexibility and enhance the protection of GPON networks.

Keywords: Wavlenght Division Multiplexed Passive Optical Network (WDM-PON), Time Division Multiplexed PON (TDM-PON), architecture, Protection, Wavelength Selective Switches (WSS), Optical Line Protection (OLP)

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Authors: Ren Zuo Wang

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In this paper, in order to investigate the joint behaviors of the Dieh-Dou structure. A pushover experiment of Dieh-Dou Jia-Dong is implemented. NDI, LVDT and image measurement system are used to measure displacements of joints and deformations of Dieh-Dou Jia-Dong. In addition, joint rotation-moment relationships of column restoring force, purlin-supporting, Dou-Shu, Dou-Gong brackets, primary beam-Gua Tong, secondary beam-Gua Tong, Tertiary beam are builied. From Jia-Dong experiments, formulations of joint rotation are proposed.

Keywords: pushover experiment, Dieh-Dou timber frame, image measurement system, joint rotation-moment relationships

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Authors: A. R. Nezamabadi, M. Veiskarami

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This paper studies free vibration of simply supported functionally graded beams with piezoelectric layers based on the first order shear deformation theory. The Young's modulus of beam is assumed to be graded continuously across the beam thickness. The governing equation is established. Resulting equation is solved using the Euler's equation. The effects of the constituent volume fractions, the influences of applied voltage on the vibration frequency are presented. To investigate the accuracy of the present analysis, a compression study is carried out with a known data.

Keywords: mechanical buckling, functionally graded beam, first order shear deformation theory, free vibration

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Authors: Wu Yiqun, Weng Jiantao

Abstract:

The human settlements of China are picked up from the land use vector map by interpreting the Thematic Map of 2014. This paper established the sustainable human settlements geographical division evaluation system and division model using GIS. The results show that: The density of human residential areas in China is different, and the density of sustainable human areas is higher, and the west is lower than that in the West. The regional differences of sustainable human settlements are obvious: the north is larger than that the south, the plain regions are larger than those of the hilly regions, and the developed regions are larger than the economically developed regions. The geographical distribution of the sustainable human settlements is measured by the degree of porosity. The degree of porosity correlates with the sustainable human settlement density. In the area where the sustainable human settlement density is high the porosity is low, the distribution is even and the gap between the settlements is low.

Keywords: GIS, geographical division, sustainable human settlements, China

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