Search results for: bearing capacity ratio

Authors: Sarra Sobti, Baelhadj Hamdi-Aïssa

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The bacteria of the soil, usually called rhizobium, have a considerable importance in agriculture because of their capacity to fix the atmospheric nitrogen in symbiosis with the plants of the family of legumes. The present work was to study the effect of the salinity on growth and nodulation of alfalfa-rhizobia symbiosis at different agricultural experimental sites in Ouargla. The experiment was conducted in 3 steps. The first one was the isolation and characterization of the Rhizobia; next, the evolution of the isolates tolerance to salinity at three levels of NaCl (6, 8,12 and 16 g/L); and the last step was the evolution of the tolerance on symbiotic characteristics. The results showed that the phenotypic characterizations behave practically as Rhizobia spp, and the effects of salinity affect the symbiotic process. The tolerance to high levels of salinity and the survival and persistence in severe and harsh desert conditions make these rhizobia highly valuable inoculums to improve productivity of the leguminous plants cultivated under extreme environments.

Keywords: rhizobia, symbiosis, salinity, tolerance, nodulation, soil, Medicago sativa L.

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Authors: Fidiana Suwitho

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Research and community service is one of important lecturer assignment in Indonesia. This article was made to meet those needs by assisting home industry entrepreneurs of various chips in Banyuwangi. Community service in this scheme are intended to increase the revenue of craftsmen of chips by improving value added of chips through food engineering technology. Ibu Anisa has produced various kinds of chips that are breadfruit chips, banana chips, yam chips, and cassava chips. In business development, Ibu Anisa facing various problems both in terms of production and management aspects. The process of production and management and marketing are still conventional so that increased demand cannot be offset by production capacity. A researcher team of STIESIA has assist partners in the processing stage, from manually to the technologically. This activity has a positive impact to However, this process has not been reached on sustainable marketing aspect, which is where the partners are still difficult to reach a wider market because of limited access.

Keywords: food engineering technology, value added of chips, community service

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Authors: Nilay Tanrıver, Birgül Benli, Nilgün Kızılcan

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Polysulfone (PSU) is a specialty engineering polymer having various industrial applications. PSU is especially used in waste water treatment membranes due to its good mechanical properties, structural and chemical stability. But it is a hydrophobic material and therefore its surface aim to pollute easily. In order to resolve this problem and extend the properties of membrane, PSU surface is rendered hydrophilic by addition of the sepiolite nanofibers. Sepiolite is one of the natural clays, which is a hydrate magnesium silicate fiber, also one of the well known layered clays of the montmorillonites where has several unique channels and pores within. It has also moisture durability, strength and low price. Sepiolite channels give great capacity of absorption and good surface properties. In this study, nanocomposites of commercial PSU and Sepiolite were prepared by solvent mixing method. Different organic solvents and their mixtures were used. Rheological characteristics of PSU-Sepiolite solvent mixtures were analyzed, the solubility of nanocomposite content in those mixtures were studied.

Keywords: nanocomposite, polysulfone, rheology, sepiolite, solution mixing

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Authors: Padma Chutoo, Elena Kulinskaya, Ilyas Bakbergenuly, Nicholas Steel, Dmitri Pchejetski

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Stroke is associated with a significant risk of morbidity and mortality. There is scarcity of research on the long-term survival after first-ever ischaemic stroke (IS) events in England with regards to effects of different medical therapies and comorbidities. The objective of this study was to model the all-cause mortality after an IS diagnosis in the adult population of England. Using a retrospective case-control design, we extracted the electronic medical records of patients born prior to or in year 1960 in England with a first-ever ischaemic stroke diagnosis from January 1986 to January 2017 within the Health and Improvement Network (THIN) database. Participants with a history of ischaemic stroke were matched to 3 controls by sex and age at diagnosis and general practice. The primary outcome was the all-cause mortality. The hazards of the all-cause mortality were estimated using a Weibull-Cox survival model which included both scale and shape effects and a shared random effect of general practice. The model included sex, birth cohort, socio-economic status, comorbidities and medical therapies. 20,250 patients with a history of IS (cases) and 55,519 controls were followed up to 30 years. From 2008 to 2015, the one-year all-cause mortality for the IS patients declined with an absolute change of -0.5%. Preventive treatments to cases increased considerably over time. These included prescriptions of statins and antihypertensives. However, prescriptions for antiplatelet drugs decreased in the routine general practice since 2010. The survival model revealed a survival benefit of antiplatelet treatment to stroke survivors with hazard ratio (HR) of 0.92 (0.90 – 0.94). IS diagnosis had significant interactions with gender and age at entry and hypertension diagnosis. IS diagnosis was associated with high risk of all-cause mortality with HR= 3.39 (3.05-3.72) for cases compared to controls. Hypertension was associated with poor survival with HR = 4.79 (4.49 - 5.09) for hypertensive cases relative to non-hypertensive controls, though the detrimental effect of hypertension has not reached significance for hypertensive controls, HR = 1.19(0.82-1.56). This study of English primary care data showed that between 2008 and 2015, the rates of prescriptions of stroke preventive treatments increased, and a short-term all-cause mortality after IS stroke declined. However, stroke resulted in poor long-term survival. Hypertension, a modifiable risk factor, was found to be associated with poor survival outcomes in IS patients. Antiplatelet drugs were found to be protective to survival. Better efforts are required to reduce the burden of stroke through health service development and primary prevention.

Keywords: general practice, hazard ratio, health improvement network (THIN), ischaemic stroke, multiple imputation, Weibull-Cox model.

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Authors: Assamen Ayalew Ejigu, Liang-Chiun Chao

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In recent semiconductor and nanotechnology, quality material synthesis, proper characterizations, and productions are the big challenges. As cuprous oxide (Cu2O) is a promising semiconductor material for photovoltaic (PV) and other optoelectronic applications, this study was aimed at to grow and characterize high quality Cu2O nanorods for the improvement of the efficiencies of thin film solar cells and other potential applications. In this study, well-structured cuprous oxide (Cu2O) nanorods were successfully fabricated using IBSD method in which the Cu2O samples were grown on silicon substrates with a substrate temperature of 400°C in an IBSD chamber of pressure of 4.5 x 10-5 torr using copper as a target material. Argon, and oxygen gases were used as a sputter and reactive gases, respectively. The characterization of the Cu2O nanorods (NRs) were done in comparison with Cu2O thin film (TF) deposited with the same method but with different Ar:O2 flow rates. With Ar:O2 ratio of 9:1 single phase pure polycrystalline Cu2O NRs with diameter of ~500 nm and length of ~4.5 µm were grow. Increasing the oxygen flow rates, pure single phase polycrystalline Cu2O thin film (TF) was found at Ar:O2 ratio of 6:1. The field emission electron microscope (FE-SEM) measurements showed that both samples have smooth morphologies. X-ray diffraction and Rama scattering measurements reveals the presence of single phase Cu2O in both samples. The differences in Raman scattering and photoluminescence (PL) bands of the two samples were also investigated and the results showed us there are differences in intensities, in number of bands and in band positions. Raman characterization shows that the Cu2O NRs sample has pronounced Raman band intensities, higher numbers of Raman bands than the Cu2O TF which has only one second overtone Raman signal at 2 (217 cm-1). The temperature dependent photoluminescence (PL) spectra measurements, showed that the defect luminescent band centered at 720 nm (1.72 eV) is the dominant one for the Cu2O NRs and the 640 nm (1.937 eV) band was the only PL band observed from the Cu2O TF. The difference in optical and structural properties of the samples comes from the oxygen flow rate change in the process window of the samples deposition. This gave us a roadmap for further investigation of the electrical and other optical properties for the tunable fabrication of the Cu2O nano/micro structured sample for the improvement of the efficiencies of thin film solar cells in addition to other potential applications. Finally, the novel morphologies, excellent structural and optical properties seen exhibits the grown Cu2O NRs sample has enough quality to be used in further research of the nano/micro structured semiconductor materials.

Keywords: defect levels, nanorods, photoluminescence, Raman modes

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Authors: Merbouha Barka, K. H. Benrahou, A. Fakrar, A. Tounsi, E. A. Adda Bedia

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This paper presents an analytical investigation on the buckling and postbuckling behaviors of thick functionally graded plates subjected to thermal load .Material properties are assumed to be temperature dependent, and graded in the thickness direction according to a simple power law distribution in terms of the volume fractions of constituents. The formulations are based on first order shear deformation plate theory taking into account Von Karman nonlinearity and initial geometrical imperfection. By applying Galerkin method, closed-form relations of postbuckling equilibrium paths for simply supported plates are determined. Analysis is carried out to show the effects of material and geometrical properties, in-plane boundary restraint, and imperfection on the buckling and postbuckling loading capacity of the plates.

Keywords: functionally graded materials, postbuckling, first order shear deformation theory, imperfection

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Authors: Lokeswara Rao P., Naga Venkata Rakesh N., V. Anantha Subramanian

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It is important to estimate, predict, and avoid the dynamic instability of high speed planing crafts. It is known that design parameters like relative location of center of gravity with respect to the dynamic lift centre and length to beam ratio of the craft have influence on the tendency to porpoise. This paper analyzes the hydrodynamic performance on the basis of the semi-empirical Savitsky method and also estimates the same by numerical simulations based on Reynolds Averaged Navier Stokes (RANS) equations using a commercial code namely, STAR- CCM+. The paper examines through the same numerical simulation considering dynamic equilibrium, the changing running trim, which results in porpoising. Some interesting results emerge from the study and this leads to early detection of the instability.

Keywords: CFD, planing hull, porpoising, Savitsky method

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Authors: Asım Egitmen, Aysen Demir, Burcu Darendeli, Fatma Ulusal, Bilgehan Güzel

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Synthesizing supercritical carbon dioxide (scCO₂) soluble precursors would be helpful for many processes of material syntheses based on scCO₂. Ligand (amphi-(1Z, 2Z)-N-(2-fluoro-3-(trifluoromethyl) phenyl)-N'-hydroxy-2-(hydroxyimino) were synthesized from chloro glyoxime and flourus aniline and Pd(II) complex (precursor) prepared. For scCO₂ deposition method, organometallic precursor was dissolved in scCO₂ and impregnated onto the SBA-15 at 90 °C and 3000 psi. Then the organometallic precursor was reduced with H₂ in the CO₂ mixture (150 psi H₂ + 2850 psi CO₂). Pd deposited support material was characterized by ICP-OES, XRD, FE-SEM, TEM and EDX analyses. The Pd loading of the prepared catalyst, measured by ICP-OES showed a value of about 1.64% mol/g Pd of catalyst. Average particle size was found 5.3 nm. The catalytic activity of prepared catalyst was investigated over Suzuki-Miyaura C-C coupling reaction in different solvent with K₂CO₃ at 50 ^oC. The conversion ratio was determined by gas chromatography.

Keywords: nanoparticle, nanotube, oximes, precursor, supercritical CO2

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Authors: Hari Krishan Sharma, Sanjay Kumar Sharma, Sushil Kumar Swar

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Inadequate transverse reinforcement is considered as the main reason for the beam column joint shear failure observed during recent earthquakes. DSP matrix consists of cement and high content of micro-silica with low water to cement ratio while the aggregates are graded quartz sand. The use of reinforcing fibres leads not only to the increase of tensile/bending strength and specific fracture energy, but also to reduction of brittleness and, consequently, to production of non-explosive ruptures. Besides, fibre-reinforced materials are more homogeneous and less sensitive to small defects and flaws. Recent works on the freeze-thaw durability (also in the presence of de-icing salts) of fibre-reinforced DSP confirm the excellent behaviour in the expected long term service life.DSP materials, including fibre-reinforced DSP and CRC (Compact Reinforced Composites) are obtained by using high quantities of super plasticizers and high volumes of micro-silica. Steel fibres with high tensile yield strength of smaller diameter and short length in different fibre volume percentage and aspect ratio tilized to improve the performance by reducing the brittleness of matrix material. In the case of High Performance Densified Small Particle Concrete (HPDSPC), concrete is dense at the micro-structure level, tensile strain would be much higher than that of the conventional SFRC, SIFCON & SIMCON. Beam-column sub-assemblages used as moment resisting constructed using HPDSPC in the joint region with varying quantities of steel fibres, fibre aspect ratio and fibre orientation in the critical section. These HPDSPC in the joint region sub-assemblages tested under cyclic/earthquake loading. Besides loading measurements, frame displacements, diagonal joint strain and rebar strain adjacent to the joint will also be measured to investigate stress-strain behaviour, load deformation characteristics, joint shear strength, failure mechanism, ductility associated parameters, stiffness and energy dissipated parameters of the beam column sub-assemblages also evaluated. Finally a design procedure for the optimum design of HPDSPC corresponding to moment, shear forces and axial forces for the reinforced concrete beam-column joint sub-assemblage proposed. The fact that the implementation of material brittleness measure in the design of RC structures can improve structural reliability by providing uniform safety margins over a wide range of structural sizes and material compositions well recognized in the structural design and research. This lead to the development of high performance concrete for the optimized combination of various structural ratios in concrete for the optimized combination of various structural properties. The structural applications of HPDSPC, because of extremely high strength, will reduce dead load significantly as compared to normal weight concrete thereby offering substantial cost saving and by providing improved seismic response, longer spans, and thinner sections, less reinforcing steel and lower foundation cost. These cost effective parameters will make this material more versatile for use in various structural applications like beam-column joints in industries, airports, parking areas, docks, harbours, and also containers for hazardous material, safety boxes and mould & tools for polymer composites and metals.

Keywords: high performance densified small particle concrete (HPDSPC), steel fibre reinforced concrete (SFRC), slurry infiltrated concrete (SIFCON), Slurry infiltrated mat concrete (SIMCON)

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Authors: Si-Gwan Kim

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In Delay Tolerant Networks (DTN), there may not exist an end-to-end path between source and destination at the time of message transmission. Employing ‘Store Carry and Forward’ delivery mechanism for message transmission in such networks usually incurs long message delays. In this paper, we present the modified Binary Spray and Wait (BSW) routing protocol that enhances the performance of the original one. Our proposed algorithm adjusts the number of forward messages depending on the number of neighbor nodes. By using beacon messages periodically, the number of neighbor nodes can be managed. The simulation using ONE simulator results shows that our modified version gives higher delivery ratio and less latency as compared to BSW.

Keywords: delay tolerant networks, store carry and forward, one simulator, binary spray and wait

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Authors: Siavash Mirahmadizoghi, Steven Bell, David Simpson

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In this work a new independent component analysis (ICA) based method for noise reduction in evoked potentials is evaluated on for auditory late responses (ALR) captured with a 63-channel electroencephalogram (EEG) from 10 normal-hearing subjects. The performance of the new method is compared with a single channel alternative in terms of signal to noise ratio (SNR), the number of channels with an SNR above an empirically derived statistical critical value and an estimate of the effect of attention on the major components in the ALR waveform. The results show that the multichannel signal processing method can significantly enhance the quality of the ALR signal and also detect the effect of the attention on the ALR better than the single channel alternative.

Keywords: auditory late response (ALR), attention, EEG, independent component analysis (ICA), multichannel signal processing

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Authors: Vinu Viswanath, Lawrence Dsouza, Ugo Ravon

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Syngas typically and intermediary gas product has a wide range of application of producing various chemical products, such as mixed alcohols, hydrogen, ammonia, Fischer-Tropsch products methanol, ethanol, aldehydes, alcohols, etc. There are several technologies available for the syngas production. An alternative to the conventional processes an attractive route of utilizing carbon dioxide and methane in equimolar ratio to generate syngas of ratio close to one has been developed which is also termed as Dry Reforming of Methane technology. It also gives the privilege to utilize the greenhouse gases like CO2 and CH4. The dry reforming process is highly endothermic, and indeed, ΔG becomes negative if the temperature is higher than 900K and practically, the reaction occurs at 1000-1100K. At this temperature, the sintering of the metal particle is happening that deactivate the catalyst. However, by using this strategy, the methane is just partially oxidized, and some cokes deposition occurs that causing the catalyst deactivation. The current research work was focused to mitigate the main challenges of dry reforming process such coke deposition, and metal sintering at high temperature.To achieve these objectives, we employed three different strategies of catalyst development. 1) Use of bulk catalysts such as olivine and pyrochlore type materials. 2) Use of metal doped support materials, like spinel and clay type material. 3) Use of core-shell model catalyst. In this approach, a thin layer (shell) of redox metal oxide is deposited over the MgAl2O4 /Al2O3 based support material (core). For the core-shell approach, an active metal is been deposited on the surface of the shell. The shell structure formed is a doped metal oxide that can undergo reduction and oxidation reactions (redox), and the core is an alkaline earth aluminate having a high affinity towards carbon dioxide. In the case of metal-doped support catalyst, the enhanced redox properties of doped CeO2 oxide and CO2 affinity property of alkaline earth aluminates collectively helps to overcome coke formation. For all of the mentioned three strategies, a systematic screening of the metals is carried out to optimize the efficiency of the catalyst. To evaluate the performance of them, the activity and stability test were carried out under reaction conditions of temperature ranging from 650 to 850 ̊C and an operating pressure ranging from 1 to 20 bar. The result generated infers that the core-shell model catalyst showed high activity and better stable DR catalysts under atmospheric as well as high-pressure conditions. In this presentation, we will show the results related to the strategy.

Keywords: carbon dioxide, dry reforming, supports, core shell catalyst

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Authors: M. M. Sadeghi, S. Vahdani

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Masonry dome structures had been widely used for covering large spans in the past. The seismic assessment of these historical structures is very complicated due to the nonlinear behavior of the material, their rigidness, and special stability configuration. The assessment method based on energy balance concept, as well as the standard pushover analysis, is used to evaluate the effectiveness of these methods in the case of masonry dome structures. The Soltanieh dome building is used as an example to which two methods are applied. The performance points are given from superimposing the capacity, and demand curves in Acceleration Displacement Response Spectra (ADRS) and energy coordination are compared with the nonlinear time history analysis as the exact result. The results show a good agreement between the dynamic analysis and the energy balance method, but standard pushover method does not provide an acceptable estimation.

Keywords: energy balance method, pushover analysis, time history analysis, masonry dome

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Authors: Dejene Ermias Mekango, Mussie Alemayehu, Gebremedhin Berhe Gebregergs, Araya Abrha Medhanye, Gelila Goba

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Background: Maternal near miss (MNM) can be used as a proxy indicator of maternal mortality ratio. There is a huge gap in life time risk between Sub-Saharan Africa and developed countries. In Ethiopia, a significant number of women die each year from complications during pregnancy, childbirth and the post-partum period. Besides, a few studies have been performed on MNM, and little is known regarding determinant factors. This study aims to identify determinants of MNM among women in Tigray region, Northern Ethiopia. Methods: a case-control study in hospital found in Tigray region, Ethiopia was conducted from January 30 - March 30, 2016. The sample included 103 cases and 205 controls recruited from women seeking obstetric care at six public hospitals. Clients having a life-threatening obstetric complication including haemorrhage, hypertensive diseases of pregnancy, dystocia, infections, and anemia or clinical signs of severe anemia in women without haemorrhage were taken as cases and those with normal obstetric outcomes were considered as controls. Cases were selected based on proportional to size allocation while systematic sampling was employed for controls. Data were analyzed using SPSS version 20.0. Binary and multiple variable logistic regression (odds ratio) analyses were calculated with 95% CI. Results: The largest proportion of cases and controls was among the ages of20–29 years, accounting for37.9 %( 39) of cases and 31.7 %( 65) of controls. Roughly 90% of cases and controls were married. About two-thirds of controls and 45.6 %( 47) of cases had gestational age between 37-41 weeks. History of chronic medical conditions was reported in 55.3 %(57) of cases and 33.2%(68) of controls. Women with no formal education [AOR=3.2;95%CI:1.24, 8.12],being less than 16 years old at first pregnancy [AOR=2.5; 95%CI:1.12,5.63],induced labor[AOR=3; 95%CI:1.44, 6.17], history of Cesarean section (C-section) [AOR=4.6; 95%CI: 1.98, 7.61] or chronic medical disorder[AOR=3.5;95%CI:1.78, 6.93], and women who traveled more than 60 minutes before reaching their final place of care[AOR=2.8;95% CI: 1.19,6.35] all had higher odds of experiencing MNM. Conclusions: The Government of Ethiopia should continue its effort to address the lack of road and health facility access as well as education, which will help reduce MNM. Work should also be continued to educate women and providers about common predictors of MNM like the history of C-section, chronic illness, and teenage pregnancy. These efforts should be carried out at the facility, community, and individual levels. The targeted follow-up to women with a history of chronic disease and C-section could also be a practical way to reduce MNM.

Keywords: maternal near miss, severe obstetric hemorrhage, hypertensive disorder, c-section, Tigray, Ethiopia

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Authors: Mehrnoosh Abouzari

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Artificial intelligence has covered all areas of human life and has helped or replaced many jobs. One of the areas of application of artificial intelligence in the police is to detect crime, identify the accused or victim and prove the crime. It will play an effective role in implementing preventive justice and creating security in the community, and improving judicial decisions. This will help improve the performance of the police, increase the accuracy of criminal investigations, and play an effective role in preventing crime and high-risk behaviors in society. This article presents and analyzes the capabilities and capacities of artificial intelligence in police and similar examples used worldwide to prove the necessity of using artificial intelligence in the police. The main topics discussed include the performance of artificial intelligence in crime detection and prediction, the risk capacity of criminals and the ability to apply arbitray institutions, and the introduction of artificial intelligence programs implemented worldwide in the field of criminal investigation for police.

Keywords: police, artificial intelligence, forecasting, prevention, software

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Authors: Chetna Tyagi, Ambuj Tripathi, Devesh Avasthi

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Graphene oxide consists of sp³ hybridization along with sp² hybridization due to the presence of different oxygen-containing functional groups on its edges and basal planes. However, its sp³ / sp² hybridization can be tuned by various methods to utilize it in different applications, like transistors, solar cells and biosensors. Ion beam irradiation can also be one of the methods to optimize sp² and sp³ hybridization ratio for its desirable properties. In this work, graphene oxide films were irradiated with 100 keV Argon ions at different fluences varying from 10¹³ to 10¹⁶ ions/cm². Synchrotron X-ray diffraction measurements showed an increase in crystallinity at the low fluence of 10¹³ ions/cm². Raman spectroscopy performed on irradiated samples determined the defects induced by the ion beam qualitatively. Also, identification of different groups and their removal with different fluences was done using Fourier infrared spectroscopy technique.

Keywords: graphene oxide, ion beam irradiation, spectroscopy, X-ray diffraction

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Authors: Marine Regnier, Pascal Bost, Matthieu Horgnies

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Some of the problems to be solved for the concrete industry are linked to the use of low-reactivity cement, the hardening of concrete under cold-weather and the manufacture of pre-casted concrete without costly heating step. The development of these applications needs to accelerate the hydration kinetics, in order to decrease the setting time and to obtain significant compressive strengths as soon as possible. The mechanisms enhancing the hydration kinetics of alite or Portland cement (e.g. the creation of nucleation sites) were already studied in literature (e.g. by using distinct additions such as titanium dioxide nanoparticles, calcium carbonate fillers, water-soluble polymers, C-S-H, etc.). However, the goal of this study was to establish a clear ranking of the efficiency of several types of additions by using a robust and reproducible methodology based on isothermal calorimetry (performed at 20°C). The cement was a CEM I 52.5N PM-ES (Blaine fineness of 455 m²/kg). To ensure the reproducibility of the experiments and avoid any decrease of the reactivity before use, the cement was stored in waterproof and sealed bags to avoid any contact with moisture and carbon dioxide. The experiments were performed on Portland cement pastes by using a water-to-cement ratio of 0.45, and incorporating different compounds (industrially available or laboratory-synthesized) that were selected according to their main composition and their specific surface area (SSA, calculated using the Brunauer-Emmett-Teller (BET) model and nitrogen adsorption isotherms performed at 77K). The intrinsic effects of (i) dry powders (e.g. fumed silica, activated charcoal, nano-precipitates of calcium carbonate, afwillite germs, nanoparticles of iron and iron oxides , etc.), and (ii) aqueous solutions (e.g. containing calcium chloride, hydrated Portland cement or Master X-SEED 100, etc.) were investigated. The influence of the amount of addition, calculated relatively to the dry extract of each addition compared to cement (and by conserving the same water-to-cement ratio) was also studied. The results demonstrated that the X-SEED®, the hydrated calcium nitrate, the calcium chloride (and, at a minor level, a solution of hydrated Portland cement) were able to accelerate the hydration kinetics of Portland cement, even at low concentration (e.g. 1%wt. of dry extract compared to cement). By using higher rates of additions, the fumed silica, the precipitated calcium carbonate and the titanium dioxide can also accelerate the hydration. In the case of the nano-precipitates of calcium carbonate, a correlation was established between the SSA and the accelerating effect. On the contrary, the nanoparticles of iron or iron oxides, the activated charcoal and the dried crystallised hydrates did not show any accelerating effect. Future experiments will be scheduled to establish the ranking of these additions, in terms of accelerating effect, by using low-reactivity cements and other water to cement ratios.

Keywords: acceleration, hydration kinetics, isothermal calorimetry, Portland cement

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Authors: Weitao Zhou, Qing Wang, Jianxin He, Shizhong Cui

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Mesoporous Tussah silk fibroin (TSF) spheres were fabricated via the self-assembly of TSF molecules in aqueous solutions. The results showed that TSF particles were approximately three-dimensional spheres with the diameter ranging from 500nm to 6μm without adherence. More importantly, the surface morphology is mesoporous structure with nano-pores of 20nm - 200nm in size. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) studies demonstrated that mesoporous TSF spheres mainly contained beta-sheet conformation (44.1 %) as well as slight amounts of random coil (13.2 %). Drug release test was performed with 5-fluorouracil (5-Fu) as a model drug and the result indicated the mesoporous TSF microspheres had a good capacity of sustained drug release. It is expected that these stable and high-crystallinity mesoporous TSF sphere produced without organic solvents, which have significantly improved drug release properties, is a very promising material for controlled gene medicines delivery.

Keywords: Tussah silk fibroin, porous materials, microsphere, drug release

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Authors: Sharon Hovav, Ilya Levner, Oren Nahum, Istvan Szabo

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In modern large-scale logistic centers (e.g., big automated warehouses), complex logistic operations performed by human staff (pickers) need to be coordinated with the operations of automated facilities (robots, conveyors, cranes, lifts, flow racks, etc.). The efficiency of advanced logistic centers strongly depends on optimizing picking technologies in synch with the facility/product layout, as well as on optimal distribution of material flows (products) in the system. The challenge is to develop a mathematical operations research (OR) tool that will optimize system cost-effectiveness. In this work, we propose a model that describes an automatic logistic center consisting of a set of workstations located at several galleries (floors), with each station containing a known number of flow racks. The requirements of each product and the working capacity of stations served by a given set of workers (pickers) are assumed as predetermined. The goal of the model is to maximize system efficiency. The proposed model includes two echelons. The first is the setting of the (optimal) number of workstations needed to create the total processing/logistic system, subject to picker capacities. The second echelon deals with the assignment of the products to the workstations and flow racks, aimed to achieve maximal throughputs of picked products over the entire system given picker capacities and budget constraints. The solutions to the problems at the two echelons interact to balance the overall load in the flow racks and maximize overall efficiency. We have developed an operations research model within each echelon. In the first echelon, the problem of calculating the optimal number of workstations is formulated as a non-standard bin-packing problem with capacity constraints for each bin. The problem arising in the second echelon is presented as a constrained product-workstation-flow rack assignment problem with non-standard mini-max criteria in which the workload maximum is calculated across all workstations in the center and the exterior minimum is calculated across all possible product-workstation-flow rack assignments. The OR problems arising in each echelon are proved to be NP-hard. Consequently, we find and develop heuristic and approximation solution algorithms based on exploiting and improving local optimums. The LC model considered in this work is highly dynamic and is recalculated periodically based on updated demand forecasts that reflect market trends, technological changes, seasonality, and the introduction of new items. The suggested two-echelon approach and the min-max balancing scheme are shown to work effectively on illustrative examples and real-life logistic data.

Keywords: logistics center, product-workstation, assignment, maximum performance, load balancing, fast algorithm

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Authors: B. Akturk, N. Yuzer, N. Kabay

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High temperature is one of the most detrimental effects that cause important changes in concrete’s mechanical, physical, and thermo-physical properties. As a result of these changes, especially high strength concrete (HSC), may exhibit damages such as cracks and spallings. To overcome this problem, incorporating polymer fibers such as polypropylene (PP) in concrete is a very well-known method. In this study, using RRH as a sustainable material instead of PP fiber in HSC to prevent spallings and improve physical and thermo-physical properties were investigated. Therefore, seven HSC mixtures with 0.25 water to binder ratio were prepared, incorporating silica fume and blast furnace slag. PP and RRH were used at 0.2-0.5% and 0.5-3% by weight of cement, respectively. All specimens were subjected to high temperatures (20 (control), 300, 600 and 900˚C) with a heating rate of 2.5˚C/min and after cooling, residual physical and thermo-physical properties were determined.

Keywords: high temperature, high strength concrete, polypropylene fiber, raw rice husk, thermo-physical properties

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Authors: Aziz Ikhlef

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Most of multi-slices CT scanners are built with detectors composed of scintillator - photodiodes arrays. The photodiodes arrays are mainly based on front-illuminated technology for detectors under 64 slices and on back-illuminated photodiode for systems of 64 slices or more. The designs based on back-illuminated photodiodes were being investigated for CT machines to overcome the challenge of the higher number of runs and connection required in front-illuminated diodes. In backlit diodes, the electronic noise has already been improved because of the reduction of the load capacitance due to the routing reduction. This translated by a better image quality in low signal application, improving low dose imaging in large patient population. With the fast development of multi-detector-rows CT (MDCT) scanners and the increasing number of examinations, the clinical community has raised significant concerns on radiation dose received by the patient in both medical and regulatory community. In order to reduce individual exposure and in response to the recommendations of the International Commission on Radiological Protection (ICRP) which suggests that all exposures should be kept as low as reasonably achievable (ALARA), every manufacturer is trying to implement strategies and solutions to optimize dose efficiency and image quality based on x-ray emission and scanning parameters. The added demands on the CT detector performance also comes from the increased utilization of spectral CT or dual-energy CT in which projection data of two different tube potentials are collected. One of the approaches utilizes a technology called fast-kVp switching in which the tube voltage is switched between 80kVp and 140kVp in fraction of a millisecond. To reduce the cross-contamination of signals, the scintillator based detector temporal response has to be extremely fast to minimize the residual signal from previous samples. In addition, this paper will present an overview of detector technologies and image chain improvement which have been investigated in the last few years to improve the signal-noise ratio and the dose efficiency CT scanners in regular examinations and in energy discrimination techniques. Several parameters of the image chain in general and in the detector technology contribute in the optimization of the final image quality. We will go through the properties of the post-patient collimation to improve the scatter-to-primary ratio, the scintillator material properties such as light output, afterglow, primary speed, crosstalk to improve the spectral imaging, the photodiode design characteristics and the data acquisition system (DAS) to optimize for crosstalk, noise and temporal/spatial resolution.

Keywords: computed tomography, X-ray detector, medical imaging, image quality, artifacts

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Authors: Aya Idriss, Esraa Othman, Lujain Malak

Abstract:

Artificial intelligence is the emulation of human intelligence processes by machines, particularly computer systems that act logically. Some of the specific applications of AI include natural language processing, speech recognition, and machine vision. Cortana is a virtual assistant and she’s an example of an AI Application. Microsoft made it possible for this app to be accessed not only on laptops and PCs but can be downloaded on mobile phones and used as a virtual assistant which was a huge success. Cortana can offer a lot apart from the basic orders such as setting alarms and marking the calendar. Its capabilities spread past that, for example, it provides us with listening to music and podcasts on the go, managing my to-do list and emails, connecting with my contacts hands-free by simply just telling the virtual assistant to call somebody, gives me instant answers and so on. A questionnaire was sent online to numerous friends and family members to perform the study, which is critical in evaluating Cortana's recognition capacity and the majority of the answers were in favor of Cortana’s capabilities. The results of the questionnaire assisted us in determining the level of Cortana's skills.

Keywords: artificial intelligence, Cortana, AI, abstract

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Authors: Mohini M. Sain, Vijay Kumar, Tasmia Tabassem, Jimi Tjong

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In the recent times, the Lithium-sulfur batteries (LiSBs) have emerged as a highly promising next generation of secondary batteries for their high theoretical specific capacity (1675 mAh/g) and low cost, and they have shown immense possibilities in utilizing in battery operated electric vehicles (BEVs). However, the commercialization of LiSBs is restricted due to the slow redox kinetics of sulfur cathode and shuttling effect of polysulfides during battery operation. Thus, the development of novel host materials is crucial for suppressing the dissolution of polysulfides into electrolyte, and this eventually helps in resolving the long-term cycling problem in LiSBs. This work provides a simple and straightforward method to design carbon materials with optimized nitrogen content with high surface area and thus simultaneously reveals new methods and strategies for realizing high performance host material design for practical LiSBs.

Keywords: Li ion battery, graphtitic carbon, electrode fabrication, BeV

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Authors: J. G. Batista, L. J. de Bessa Neto, M. A. F. B. Lima, J. R. Leite, J. I. de Andrade Nunes

Abstract:

The robot manipulator is an equipment that stands out for two reasons: Firstly because of its characteristics of movement and reprogramming, resembling the arm; secondly, by adding several areas of knowledge of science and engineering. The present work shows the development of the prototype of a robotic manipulator driven by a Programmable Logic Controller (PLC), having two degrees of freedom, which allows the movement and displacement of mechanical parts, tools, and objects in general of small size, through an electronic system. The aim is to study direct and inverse kinematics of the robotic manipulator to describe the translation and rotation between two adjacent links of the robot through the Denavit-Hartenberg parameters. Currently, due to the many resources that microcomputer systems offer us, robotics is going through a period of continuous growth that will allow, in a short time, the development of intelligent robots with the capacity to perform operations that require flexibility, speed and precision.

Keywords: Denavit-Hartenberg, direct and inverse kinematics, microcontrollers, robotic manipulator

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Authors: Aleksander Ostrowski, Hugh J. Byrne, Roland Sanctuary

Abstract:

Investigation of the polymer interphases is an emerging field nowadays. In many cases interphases determine the functionality of a system. There is a great demand for exploration of fundamental understanding of the interphases and elucidation of their formation, dimensions dependent on various influencing factors, change of functional properties, etc. The epoxy applied on porous glass penetrates its pores with an extent dependent on the pore size, temperature and epoxy components mixing ratio. Developed over the recent time challenging sample preparation procedure allowed to produce very smooth epoxy-porous glass cross-sections. In this study, Raman spectroscopy was used to investigate the epoxy-porous glass interphases. It allowed for chemical differentiation between different regions at the cross-section and determination of the degree of cure of epoxy system in the porous glass.

Keywords: interphases, Raman spectroscopy, epoxy, porous glass

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Authors: Nitin Ghule, S. G. Taji

Abstract:

A mathematical model of hot-wall condensers used in refrigerators is presented. The model predicts the heat transfer characteristics of condenser and the effects of various design and operating parameters on condenser tube length and capacity. A finite element approach was used to model the condenser. The condenser tube is divided into elemental units, with each element consisting of adhesive tape, refrigerant tube and outer metal sheet. The heat transfer characteristics of each section are then analyzed by considering the heat transfer through the tube wall, tape and the outer sheet. Variations in inner heat transfer coefficient and pressure drop are considered depending on temperature, fluid phase, type of flow and orientation of tube. Variation in outer heat transfer coefficient is also taken into account. Various materials were analysed for the tube, tape and outer sheet.

Keywords: condenser, domestic refrigerator, heat transfer, mathematical model

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Authors: Thidaya Thitiapichart

Abstract:

The effect of additional magnesium oxide (MgO) was investigated by using the tungsten oxide supported on silica catalyst (WOx/SiO2) physically mixed with MgO in a weight ratio 1:1. The both fresh and spent catalysts were characterized by FT-Raman spectrometer, UV-Vis spectrometer, X-Ray diffraction (XRD), and temperature programmed oxidation (TPO). The results indicated that the additional MgO could enhance the conversion of trans-2-butene due to isomerization reaction. However, adding MgO would increase the amount of coke deposit on the WOx/SiO2 catalyst. The TPO profile presents two peaks when the WOx/SiO2 catalyst was physically mixed with MgO. The further peak was suggested to be coming from the coke precursor that could be produced by isomerization reaction of the undesired product. Then, the occurred coke precursor could deposit and form coke on the acid catalyst.

Keywords: coke formation, metathesis, magnesium oxide, physically mix

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Authors: Sahar Elkaee Behjati

Abstract:

Air pollution, particularly with dust, is one of the biggest issues Tehran is dealing with, and the city's green space which consists of trees has a critical role in absorption of it. The question this study aimed to investigate was which tree species the highest uptake capacity of the dust and carbon have suspended in the air. On this basis, 30 samples of trees from two different districts in Tehran were collected, and after washing and centrifuging, the samples were oven dried. The results of the study revealed that Ulmus minor had the highest amount of deposited dust in both districts. In addition, it was found that in Chamran district Ailanthus altissima and in Gandi district Ulmus minor has had the highest absorption of deposited carbon. Therefore, it could be argued that decision making on the selection of species for urban green spaces should take the above-mentioned parameters into account.

Keywords: dust, leaves, uptake total carbon, Tehran, tree species

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Authors: Hategekimana Jean Paul, Irakoze Josiane, Ishimweyizerwe Valentin, Iradukunda Dieudonne, Uwanyirigira Jeannette

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Orange fleshed sweet potatoes (OFSP) are highly grown and are available plenty in rural and urban local markets and its contribution in reduction of food insecurity in Rwanda is considerable. But the postharvest loss of this commodity is a critical challenge due to its high perishability. Several research activities have been conducted on how fresh food commodities can be transformed into extended shelf life food products for prevention of post-harvest losses. However, such activity was not yet well studied in Rwanda. The aim of the present study was the processing of backed products from (OFSP)combined with wheat composite flour and assess the nutritional content and consumer acceptability of new developed products. The perishability of OFSP and their related lack during off season can be eradicated by producing cake, doughnut and bread with OFSP puree or flour. The processing for doughnut and bread were made by making OFSP puree and other ingredients then a dough was made followed by frying and baking while for cake OFSP was dried through solar dryer to have a flour together with wheat flour and other ingredients to make dough cake and baking. For each product, one control and three experimental samples, (three products in three different ratios (30,40 and50%) of OFSP and the remaining percentage of wheat flour) were prepared. All samples including the control were analyzed for the consumer acceptability (sensory attributes). Most preferred samples (One sample for each product with its control sample and for each OFSP variety) were analyzed for nutritional composition along with control sample. The Cake from Terimbere variety and Bread from Gihingumukungu supplemented with 50% OFSP flour or Puree respectively were most acceptable except Doughnut from Vita variety which was highly accepted at 50% of OFSP supplementation. The moisture, ash, protein, fat, fiber, Total carbohydrate, Vitamin C, reducing sugar and minerals (Sodium, Potassium and Phosphorus.) content was different among products. Cake was rich in fibers (14.71%), protein (6.590%), and vitamin c(19.988mg/100g) compared to other samples while bread found to be rich in reducing sugar with 12.71mg/100g compared to cake and doughnut. Also doughnut was found to be rich in fat content with 6.89% compared to other samples. For sensory analysis, doughnut was highly accepted in ratio of 60:40 compared to other products while cake was least accepted at ratio of 50:50. The Proximate composition and minerals content of all the OFSP products were significantly higher as compared to the control samples.

Keywords: post-harvest loss, OFSP products, wheat flour, sensory evaluation, proximate composition

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Authors: Funda Buyuk Mazari, Adnan Mazari, Antonin Havelka, Jakub Wiener, Jawad Naeem

Abstract:

The use of super absorbent polymers (SAP) for moisture absorption and comfort is still unexplored. In this research the efficiency of different SAP fibrous webs are determined under different moisture percentage to examine the sorption and desorption efficiency. The SAP fibrous web with low thickness and high moisture absorption are tested with multilayer sandwich structure of car seat cover to determine the moisture absorption through cover material. Sweating guarded hot plate (SGHP) from company Atlas is used to determine the moisture permeability of different car seat cover with superabsorbent layer closed with impermeable polyurethane foam. It is observed that the SAP fibrous layers are very effective in absorbing and desorbing water vapor under extreme high and low moisture percentages respectively. In extreme humid condition (95 %RH) the 20g of SAP layer absorbs nearly 3g of water vapor per hour and reaches the maximum absorption capacity in 6 hours.

Keywords: car seat, comfort, SAF, superabsorbent

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