Search results for: ratio of shear modulus and rolling shear modulus

Authors: Joe Hachem, Marianne Cuif-Sjostrand, Thierry Schuhler, Dominique Orhon, Assaad Zoughaib

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The exhaust gas recirculation, EGR, implementation on gas turbines is increasingly gaining the attention of many researchers. This emerging technology presents many advantages, such as lowering the NOx emissions and facilitating post-combustion carbon capture as the carbon dioxide concentration in the cycle increases. As interesting as this technology may seem, the gas turbine, or its thermodynamic equivalent, the Brayton cycle, shows an intrinsic efficiency decrease with increasing EGR rate. In this paper, a thermodynamic model is presented to show the cycle efficiency decrease with EGR, alternative values of design parameters of both the pressure ratio (PR) and the turbine inlet temperature (TIT) are then proposed to optimize the cycle efficiency with different EGR rates. Results show that depending on the given EGR rate, both the design PR & TIT should be increased to compensate for the deficit in efficiency.

Keywords: gas turbines, exhaust gas recirculation, design parameters optimization, thermodynamic approach

Procedia PDF Downloads 134

Authors: H. Golchoobian, S. Saedodin, M. H. Taheri, A. Sarafraz

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In this paper, natural convection in an attic is numerically investigated. The geometry of the problem is considered to be a triangular enclosure. ANSYS Fluent software is used for modeling and numerical solution. This study is for steady state. Four right-angled triangles with height to base ratios of 2, 1, 0.5 and 0.25 are considered. The behavior of various parameters related to its performance, including temperature distribution and velocity vectors are evaluated, and graphs for the Nusselt number have been drawn. Also, in this study, the effect of geometric shape of enclosure with different height-to-base ratios has been evaluated for three types of boundary conditions of winter, summer day and one another state. It can be concluded that as the bottom side temperature and ratio of base to height of the enclosure increases, the convective effects become more prominent and circulation happened.

Keywords: enclosure, natural convection, numerical solution, Nusselt number, triangular

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Authors: Austin Ikechukwu Gbasouzor, Sam Nna Omenyi, Sabuj Malli

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This study is an extension of the previous work done with ARS-680 Environmental Chamber. Drying is a complex operation that demands much energy and time. Drying is essentially important for preservation of ginger rhizome. Drying of ginger was modeled, and then the effective diffusion coefficient and activation energy where determined. For this purpose, the experiments were done at six levels of varied temperature ranging from (10, 20, 30, 40, 50, 60°C). The average effective diffusion coefficient for their studies samples for temperature range of 40°C to 70°C was 4.48 x10-10m²/s, 4.96 x10-10m²/s, and 5.31 x10-10m²/s for 0.8, 1.5 and 3m/s drying air velocity respectively. These values closely agreed with the values of effective diffusion coefficients obtained in these studies for the variously treated ginger rhizomes and test conducted.

Keywords: activation energy, diffusion coefficients, drying model, drying time, ginger rhizomes, moisture ratio, thin layer

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Authors: Amir Mahmoudi

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In this research the effects of adding silica and alumina nanoparticles on flow ability and compressive strength of cementitious composites based on Portland cement were investigated. In the first stage, the rheological behavior of different samples containing nanosilica, nanoalumina and polypropylene, polyvinyl alcohol and polyethylene fibers were evaluated. With increasing of nanoparticles in fresh samples, the slump flow diameter reduced. Fibers reduced the flow ability of the samples and viscosity increased. With increasing of the micro silica particles to cement ratio from 2/1 to 2/2, the slump flow diameter increased. By adding silica and alumina nanoparticles up to 3% and 2% respectively, the compressive strength increased and after decreased. Samples containing silica nanoparticles and fibers had the highest compressive strength.

Keywords: Portland cement, composite, nanoparticles, compressive strength

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Authors: Siti Rahmah Shamsuri, Eiichiro Matsubara, Shohei Shiomi

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The 1D nanomaterial is far surpassed the 0D nanomaterial. It does not just offer most of the benefit of the 0D nanomaterial such as the large surface area, a great number of active site and an efficient interfacial charge transfer but also can assemble into free-standing and flexible electrode due to their high aspect ratio. Thus, it is essential to develop a simple and ease synthesis of this 1D nanomaterial for the practical application. Here, nickel nanowire/cellulose hybrid has been successfully fabricated via a simple liquid-phase method with the assist of the magnetic field. A finer nickel nanowire was heterogeneously nucleated on the surface of the cellulose fiber, which demonstrated the effect of the hydroxyl group on the cellulose structure. The result of the nickel nanowire size was found to vary from 66-114 nm. A detailed discussion on the mechanism of the nickel nanowire/ cellulose hybrid formation is also shown in this paper.

Keywords: cellulose nanofiber, liquid-phase reduction, metal nanowire, nano hybrid material

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Authors: Mustafa M. Donma, Orkide Donma

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Obesity is a low-grade inflammatory state. Childhood obesity is a multisystem disease, which is associated with a number of complications as well as potentially negative consequences. Gender is an important universal risk factor for many diseases. Hematological indices differ significantly by gender. This should be considered during the evaluation of obese children. The aim of this study is to detect hematologic indices that differ by gender in morbid obese (MO) children. A total of 134 MO children took part in this study. The parents filled an informed consent form and the approval from the Ethics Committee of Namik Kemal University was obtained. Subjects were divided into two groups based on their genders (64 females aged 10.2±3.1 years and 70 males aged 9.8±2.2 years; p ≥ 0.05). Waist-to-hip as well as head-to-neck ratios and body mass index (BMI) values were calculated. The children, whose WHO BMI-for age and sex percentile values were > 99 percentile, were defined as MO. Hematological parameters [haemoglobin, hematocrit, erythrocyte count, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, red blood cell distribution width, leukocyte count, neutrophil %, lymphocyte %, monocyte %, eosinophil %, basophil %, platelet count, platelet distribution width, mean platelet volume] were determined by the automatic hematology analyzer. SPSS was used for statistical analyses. P ≤ 0.05 was the degree for statistical significance. The groups included children having mean±SD value of BMI as 26.9±3.4 kg/m² for males and 27.7±4.4 kg/m² for females (p ≥ 0.05). There was no significant difference between ages of females and males (p ≥ 0.05). Males had significantly increased waist-to-hip ratios (0.95±0.08 vs 0.91±0.08; p=0.005) and mean corpuscular hemoglobin concentration values (33.6±0.92 vs 33.1±0.83; p=0.001) compared to those of females. Significantly elevated neutrophil (4.69±1.59 vs 4.02±1.42; p=0.011) and neutrophil-to-lymphocyte ratios (1.70±0.71 vs 1.39±0.48; p=0.004) were detected in females. There was no statistically significant difference between groups in terms of C-reactive protein values (p ≥ 0.05). Adipose tissue plays important roles during the development of obesity and associated diseases such as metabolic syndrom and cardiovascular diseases (CVDs). These diseases may cause changes in complete blood cell count parameters. These alterations are even more important during childhood. Significant gender effects on the changes of neutrophils, one of the white blood cell subsets, were observed. The findings of the study demonstrate the importance of considering gender in clinical studies. The males and females may have distinct leukocyte-trafficking profiles in inflammation. Female children had more circulating neutrophils, which may be the indicator of an increased risk of CVDs, than male children within this age range during the late stage of obesity. In recent years, females represent about half of deaths from CVDs; therefore, our findings may be the indicator of the increasing tendency of this risk in females starting from childhood.

Keywords: children, gender, morbid obesity, neutrophil-to-lymphocyte ratio

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Authors: Oluwagbenga O. Isaac Orimoogunje, Omolola Helen Oshosanya

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The study examined land management in a typical watershed in southwestern Nigeria with a view to ascertaining its impact on land suitability analysis for rice cultivation and production. The study applied the analytical hierarchy process (AHP), weighted overlay analysis (WOA), multi-criteria decision-making techniques, and suitability map calculations within a Geographic Information System environment. Five main criteria were used, and these include climate, topography, soil fertility, macronutrients, and micronutrients. A consistency ratio (CR) of 0.067 was obtained for rice cultivation. The results showed that 95% of the land area is suitable for rice cultivation, with pH units ranging between 4.6 and 6.0, organic matter of 1.4–2.5 g kg-1 and base saturation of more than 80%. The study concluded that the Ofiki watershed is a potential site for large-scale rice cultivation in a sustainable capacity.

Keywords: land management, land characteristics, land suitability, rice production, watershed

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Authors: Ilhem Ouelhazi, Mouna Elakhdar, Lakdar Kairouani

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A computer simulation model for a combined ejector-vapor compression cycle that uses working fluid R134a. A refrigeration system was developed which combines a basic vapor compression refrigeration cycle with an ejector cooling cycle. A one-dimensional mathematical model was developed using the equations governing the flow and thermodynamics based on the constant area ejector flow model. The effects of the operating parameters on the cooling capacity, the performance coefficient, and the entrainment ratio are studied. The current model is based on the NIST-REFPROP database for refrigerants properties calculations. The simulated performance is compared with the available experimental data from the literature for validation.

Keywords: combined refrigeration cycle, constant area ejector, R134a, ejector-cooling cycle, performance, mathematical simulation, vapor compression cycle

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Authors: Noor-ul-Amin, Lubna Nawab, Sabiha Sultana

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Geopolymer with different silica to alumina ratio with iron have been synthesized using sodium silicate, aluminum, and iron salts as a source of silica, alumina and iron source, and sodium/potassium hydroxide as an alkaline medium. The iron source will be taken from iron (III) salts and laterite clay samples. Laterite has been used as a natural source of iron in modified geopolymer. The synthesized iron modified geopolymer was submitted to the different aggressive environment, including chloride and sulphate solutions in different concentration. Different experimental techniques, including XRF, XRD, and FTIR, were used to study the bonding nature and effect of aggressive environment on geopolymer. The major phases formed during geopolymerization are sodalite (Na₄Al₃Si₃O₁₂Cl), albite (NaAlSi₃O₈), hematite (Fe₂O₃), and chabazite as confirmed from the XRD results. The resulting geopolymer showed greater resistance to sulphate and chloride as compared to the normal geopolymer.

Keywords: modified geopolymer, laterite, chloride, sulphate

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Authors: Alla V. Goncharova, Tatyana A. Karpenyuk, Yana S. Tsurkan, Rosa U. Beisembaeva, Togzhan D. Mukasheva, Ludmila V. Ignatova, Ramza Z. Berzhanova

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In this work the effect of culturing conditions of filamentous fungi Penicillium raistrickii, Penicillium anatolicum, Fusarium sp. on biomass yield, the content of total lipids and fatty acids was studied. It has been established that in time the process of lipids accumulation correlated with biomass growth of cultures, reaching maximum values in stationary growth phase. Biomass yield and accumulation of general lipids was increased by adding zinc to the culture medium. The more intensive accumulation of biomass and general lipids was observed at temperature 18°C. Lowering the temperature of culturing has changed the ratio of saturated: Unsaturated fatty acids in the direction of increasing the latter.

Keywords: biomass, culturing conditions, fungi, fatty acids (FA), growth dynamics, lipids

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Authors: Amandeep Singh, Surinder Singh

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A slotted Bow-Tie microstrip patch antenna utilizing input of coplanar waveguide for high frequency wireless applications is proposed and analyzed in this work. RT/Duroid 5880 with its dielectric constant 2.2 is opted for the experimentation to analyze the proposed microstrip slot antenna. This antenna is exclusively designed for the frequency range of 10 GHz to 11 GHz and modelling parameters are obtained from the already existing data and dimensions of antenna are adjusted by employing some corrugated slots in the Bowtie shape to obtain the required bandwidth so that it can radiate within the specified range. The characteristics of proposed antenna are measured by a FEM electromagnetic field solver and it is found that the reflection coefficient, voltage standing wave ratio, radiated gain, feed point impedance, radiation efficiency are in a good agreement. This antenna is also exhibiting an absolute bandwidth of 1000 MHz. The validated results indicate that the proposed bowtie microstrip slot antenna comes under the wideband category and utilized in the wireless application ranges between the 10 GHz – 11 GHz.

Keywords: CPW, bowtie, FEM, corrugated

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Authors: Yassine Meraihi, Dalila Acheli, Rabah Meraihi

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Vehicular Ad hoc Network (VANET) is a special case of Mobile Ad hoc Network (MANET) used to establish communications and exchange information among nearby vehicles and between vehicles and nearby fixed infrastructure. VANET is seen as a promising technology used to provide safety, efficiency, assistance and comfort to the road users. Routing is an important issue in Vehicular Ad Hoc Network to find and maintain communication between vehicles due to the highly dynamic topology, frequently disconnected network and mobility constraints. This paper evaluates the performance of two most popular proactive routing protocols OLSR and DSDV in real city traffic scenario on the basis of three metrics namely Packet delivery ratio, throughput and average end to end delay by varying vehicles density and transmission range.

Keywords: DSDV, OLSR, quality of service, routing protocols, VANET

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Authors: Brenda Cecilia Ledesma, Andrea Beltramone

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This work deals with the bio-waste valorization approach for catalyst development, the use of products derived from biomass as raw material and the obtaining of biofuels. In this research, activated carbons were synthesized from the orange peel using different synthesis conditions. With the activated carbons obtained with the best structure and texture, PtIr bimetallic catalysts were prepared. Carbon activation was carried out through a chemical process with phosphoric acid as an activating agent, varying the acid concentration, the ratio substrate/activating agent and time of contact between them. The best support was obtained using a carbonization time of 1 h, the temperature of carbonization of 470oC, the phosphoric acid concentration of 50 wt.% and a BET area of 1429 m2/g. Subsequently, the metallic nanoparticles were deposited in the activated carbon to use the solid as a catalytic material for the hydrogenation of HMF to 2,5-DMF. The catalyst presented an excellent performance for biofuels generation.

Keywords: orange peel, bio-waste valorization, platinum, iridium, 5-hydroxymethylfurfural

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Authors: Hong Kai, Zhong Jun Jie, Chen Lin Qi, Wang Chen Guang

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There are inefficient global scheduling parallelism and local scheduling parallelism prone to processor starvation in current scheduling algorithms. Regarding this issue, this paper proposed a load-aware queue partitioning scheduling strategy by first allocating the queues according to the number of processor cores, calculating the load factor to specify the load queue capacity, and it assigned the awaiting nodes to the appropriate perceptual queues through the precursor nodes and the communication computation overhead. At the same time, real-time computation of the load factor could effectively prevent the processor from being starved for a long time. Experimental comparison with two classical algorithms shows that there is a certain improvement in both performance metrics of scheduling length and task speedup ratio.

Keywords: load-aware, scheduling algorithm, perceptual queue, heterogeneous multi-core

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Authors: Jamal A. Radaideh, Ziad N. Shatnawi

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Both indoor and outdoor air quality is investigated throughout residential areas of Al Hofuf city/ Eastern province of Saudi Arabia through a multi‐week multiple sites measurement and sampling survey. Concentration levels of five criteria air pollutants, including carbon dioxide (CO2), carbon monoxide (CO), nitrous dioxide (NO2), sulfur dioxide (SO2) and total volatile organic compounds (TVOC) were measured and analyzed during the study period from January to May 2014. For this survey paper, three different sites, roadside RS, urban UR, and rural RU were selected. Within each site type, six locations were assigned to carryout air quality measurements and to study varying indoor/outdoor air quality for each pollutant. Results indicate that a strong correlation between indoor and outdoor air exists. The I/O ratios for the considered criteria pollutants show that the strongest relationship between indoor and outdoor air is found by analyzing of carbon dioxide, CO2 (0.88), while the lowest is found by both NO2 and SO2 (0.7).

Keywords: criteria air pollutants, indoor/outdoor air pollution, indoor/outdoor ratio, Saudi Arabia

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Authors: Debraj Gangopadhyay, Moumita Das, Ranjan K. Singh, Poonam Tandon

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Creatinine is a toxic chemical waste generated from muscle metabolism. Abnormally high levels of creatinine in the body fluid indicate possible malfunction or failure of the kidneys. This leads to a condition termed as creatinine induced nephrotoxicity. N-acetylcysteine is an antioxidant drug which is capable of preventing creatinine induced nephrotoxicity and is helpful to treat renal failure in its early stages. Taurine is another antioxidant drug which serves similar purpose. The kidneys have a natural power that whenever reactive oxygen species radicals increase in the human body, the kidneys make an antioxidant shell so that these radicals cannot harm the kidney function. Taurine plays a vital role in increasing the power of that shell such that the glomerular filtration rate can remain in its normal level. Thus taurine protects the kidneys against several diseases. However, taurine also has some negative effects on the body as its chloramine derivative is a weak oxidant by nature. N-acetylcysteine is capable of inhibiting the residual oxidative property of taurine chloramine. Therefore, N-acetylcysteine is given to a patient along with taurine and this combination is capable of suppressing the negative effect of taurine. Both N-acetylcysteine and taurine being affordable, safe, and widely available medicines, knowledge of the mechanism of their combined effect on creatinine, the favored route of administration, and the proper dose may be highly useful in their use for treating renal patients. Raman spectroscopy is a precise technique to observe minor structural changes taking place when two or more molecules interact. The possibility of formation of a complex between a drug molecule and an analyte molecule in solution can be explored by analyzing the changes in the Raman spectra. The formation of a stable complex of creatinine with N-acetylcysteinein vitroin aqueous solution has been observed with the help of Raman spectroscopic technique. From the Raman spectra of the mixtures of aqueous solutions of creatinine and N-acetylcysteinein different molar ratios, it is observed that the most stable complex is formed at 1:1 ratio of creatinine andN-acetylcysteine. Upon drying, the complex obtained is gel-like in appearance and reddish yellow in color. The complex is hygroscopic and has much better water solubility compared to creatinine. This highlights that N-acetylcysteineplays an effective role in reducing the toxic effect of creatinine by forming this water soluble complex which can be removed through urine. Since the drug taurine is also known to be useful in reducing nephrotoxicity caused by creatinine, the aqueous solution of taurine with those of creatinine and N-acetylcysteinewere mixed in different molar ratios and were investigated by Raman spectroscopic technique. It is understood that taurine itself does not undergo complexation with creatinine as no additional changes are observed in the Raman spectra of creatinine when it is mixed with taurine. However, when creatinine, N-acetylcysteine and taurine are mixed in aqueous solution in molar ratio 1:1:3, several changes occurring in the Raman spectra of creatinine suggest the diminishing toxic effect of creatinine in the presence ofantioxidant drugs N-acetylcysteine and taurine.

Keywords: creatinine, creatinine induced nephrotoxicity, N-acetylcysteine, taurine

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Authors: Bhaveek Maini, Sanjay Dhanka, Surita Maini

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Electroencephalography (EEG) is used to classify several epileptic seizures worldwide. It is a very crucial task for the neurologist to identify the epileptic seizure with manual EEG analysis, as it takes lots of effort and time. Human error is always at high risk in EEG, as acquiring signals needs manual intervention. Disease diagnosis using machine learning (ML) has continuously been explored since its inception. Moreover, where a large number of datasets have to be analyzed, ML is acting as a boon for doctors. In this research paper, authors proposed two different ML models, i.e., logistic regression (LR) and Naïve Bayes (NB), to predict epileptic seizures based on general parameters. These two techniques are applied to the epileptic seizures recognition dataset, available on the UCI ML repository. The algorithms are implemented on an 80:20 train test ratio (80% for training and 20% for testing), and the performance of the model was validated by 10-fold cross-validation. The proposed study has claimed accuracy of 81.87% and 95.49% for LR and NB, respectively.

Keywords: epileptic seizure recognition, logistic regression, Naïve Bayes, machine learning

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Authors: M. S. E. Hamroun, K. Bachari, A. Berrayah, L. Mechernene, L. Guerbous

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Composite films containing homogeneously dispersed scintillation nano-particles of Lu₂SiO₅:Ce³⁺, in optically transparent polymer matrix, have been prepared and characterized through X-ray diffraction, differential scanning calorimetric (DSC), thermogravimetric analysis (ATG), dynamic mechanical analysis (DMA), electron scanning microscopy morphology (SEM) and photoluminescence (PL). Lu₂SiO₅:Ce³⁺ scintillator powder was successfully synthesized via Sol-Gel method. This study is realized with different mass ratios of nano-particles embedded in polystyrene and polylactic acid polymer matrix (5, 10, 15, 20%) to see the influence of nano-particles on the mechanical, structural and optical properties of films. The composites have been prepared with 400 µm thickness. It has found that the structural proprieties change with mass ratio on each sample. PL photoluminescence shows the characteristic Lu₂SiO₅:Ce³⁺ emission in the blue region and intensity varied for each film.

Keywords: nano-particles, sol gel, photoluminescence, Ce³⁺, scintillator, polystyrene

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Authors: M. Nafis Alfarizi, Dinda A. Utami, Arif Hidayat

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Biodiesel is one solution to overcome the use of petroleum fuels. Many alternative feedstocks that can be used among which canola oil. The purpose of this study was to determine the ability of canola oil and KOH for the trans-esterification reaction in biodiesel production. Canola oil has a very high purity that can be used as an alternative feedstock for biodiesel production and expected it will be produced biodiesel with excellent quality. In this case of study, we used trans-esterification process wherein the triglyceride is reacted with an alcohol with KOH as a catalyst, and it will produce biodiesel and glycerol as byproduct and we choose trans-esterification process because canola oil has a 0,445% FFA content. The variables studied in this research include the comparison of canola oil and methanol, temperature, time, and the percent of catalyst used. In this study the method of analysis we use GCMS and FTIR to know what the characteristic in canola oil. Development of canola oil seems to be the perfect solution to produce high-quality biodiesel. The reaction conditions resulted in 97.87% -w methyl ester (biodiesel) product by using a 0.5% wt KOH catalyst with canola and methanol ratio 1:8 at 60°C.

Keywords: biodiesel, canola oil, KOH, trans-esterification

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Authors: W. T. Hsu, H. L. Tsai

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The rapid aging of the population is a common trend in the world. However, the progress of modern medical technology has increased the average life expectancy. The global population structure has changed dramatically, and the elderly population has risen rapidly. In the face of rapid population growth, it must be noted issues of the aging population must face up to, which are the physiological, psychological, and social problems associated with aging. This study aims to investigate how insurance agents are actively dealing with an aging society, their own aging anxiety, and their exercise habits. Purposive sampling was the sampling method of this study, a total of 204 respondents were surveyed and 204 valid surveys were returned. The returned valid ratio was 100%. Statistical method included descriptive statistics, t-test, and one-way ANOVA. The results of the study found that the insurance agent’s age, seniority, exercise habits to aging anxiety are significantly different.

Keywords: insurance practitioners, aging anxiety, exercise habits, elderly

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Authors: E. L. Elghazy, A. M. Sanad, M. G. Ghoneim

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Over the past two decades research has shown that fiber reinforced polymers can be efficiently, economically and safely used for strengthening and rehabilitation of reinforced concrete (RC) structures. Designing FRP confined concrete columns requires reliable analytical tools that predict the level of performance and ductility enhancement. A numerical procedure is developed aiming at determining the type and thickness of FRP jacket needed to achieve a certain level of ductility enhancement. The procedure starts with defining the stress strain curve, which is used to obtain moment curvature relationship then displacement ductility ratio of reinforced concrete cross-sections subjected to bending moment and axial force. Three sets of published experimental tests were used to validate the numerical procedure. Comparisons between predicted results obtained by using the proposed procedure and actual results of experimental tests proved the reliability of the proposed procedure.

Keywords: columns, confinement, ductility, FRP, numerical

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Authors: Adriana Hernandez-Martinez, Edgar D. Ramon-Raygoza

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Currently, there has been a great interest, during the last years, on graphene due to its lubricant properties on friction and antiwear processes. Likewise, fluorographene has also been gaining renown due to its excellent chemical and physical properties which have been mostly applied in the electronics industry. Nevertheless, its tribological properties haven’t been analyzed thoroughly. In this paper, fluorographene was examined as an extreme pressure additive and the nano lubricant made with a cutting fluid and fluorographene in the range of 0.01-0.5% wt, which proved to withstand 53.78% more pounds than the conventional product and 7.12% more than the nano lubricant with graphene in a range between 0.01-0.5% wt. Said extreme pressure test was carried out with a Pin and Vee Block Tribometer following an ASTM D3233A test. The fluorographene used has a low C/F ratio, which reflects a greater presence of atomic fluorine and its low oxygen percentage, supports the substitution of oxygen-containing groups by fluorine. XPS Spectra shows high atomic fluorine content of 56.12%, and SEM analysis details the formation of long and clear crystalline structures, in the fluorographene used.

Keywords: extreme pressure additive, fluorographene, nanofluids, nanolubricant

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Authors: L. O. Luengas, E. V. Morales, L. F. G. De Souza, I. S. Bott

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Duplex Stainless Steels are well known for its good mechanical properties, and corrosion resistance. However, when submitted to heating, these features can be lost since the good properties are strongly dependent on the austenite-ferrite phase ratio which has to be approximately 1:1 to keep the phase balance. In a welded joint, the transformation kinetics at the heat affected zone (HAZ) is a function of the cooling rates applied which in turn are dependent on the heat input. The HAZ is usually ferritized at these temperatures, and it has been argued that small variations of the chemical composition can play a role in the solid state transformation sequence of ferrite to austenite during cooling. The δ → γ transformation has been reported to be massive and diffusionless due to the fast cooling rate, but it is also considered a diffusion controlled transformation. The aim of this work is to evaluate the effect of different heat inputs on the HAZ of two duplex stainless steels UNS S32304 and S32750, obtained by physical simulation.

Keywords: duplex stainless steels, HAZ, microstructural characterization, physical simulation

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Authors: Mihir Mouchum Hazarika, Maddali Ramgopal, Souvik Bhattacharyya

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The thermodynamic analysis shows that the performance of the R744 based transcritical refrigeration cycle drops drastically for higher ambient temperatures. This is due to the peculiar s-shape of the isotherm in the supercritical region. However, subcooling of the refrigerant at the gas cooler exit enhances the performance of the R744 based system. The present study is carried out to analyze the R744 based transcritical system with dedicated mechanical subcooling cycle. Based on this proposed cycle, the thermodynamic analysis is performed, and optimum operating parameters are determined. The amount of subcooling and the pressure ratio in the subcooling cycle are the parameters which are needed to be optimized to extract the maximum COP from this proposed cycle. It is expected that this study will be helpful in implementing the dedicated subcooling cycle with R744 based transcritical system to improve the performance.

Keywords: optimization, R744, subcooling, transcritical

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Authors: T. Mohanarajah, J. Rizk, M. Nagrial, A. Hellany

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This paper analyses numerous features of the synchronous Reluctance Motor (Syn-RM) and propose a rotor for high electrical torque, power factor & efficiency using Finite Element Method (FEM). A comprehensive analysis completed on solid rotor structure while the total thickness of the flux guide kept constant. A number of tests carried out for nine different studies to find out optimum location of the flux guide, the optimum location of multiple flux guides & optimum wall thickness between flux guides for high-performance reluctance machines. The results are concluded with the aid of FEM simulation results, the saliency ratio and machine characteristics (location, a number of barriers & wall width) analysed.

Keywords: electrical machines, finite element method, synchronous reluctance machines, variable reluctance machines

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Authors: Essam Al Daoud

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Genome rearrangement is an important area in computational biology and bioinformatics. The basic problem in genome rearrangements is to compute the edit distance, i.e., the minimum number of operations needed to transform one genome into another. Unfortunately, unsigned genome rearrangement problem is NP-hard. In this study an improved ant colony optimization algorithm to approximate the edit distance is proposed. The main idea is to convert the unsigned permutation to signed permutation and evaluate the ants by using Kaplan algorithm. Two new operations are added to the standard ant colony algorithm: Replacing the worst ants by re-sampling the ants from a new probability distribution and applying the crossover operations on the best ants. The proposed algorithm is tested and compared with the improved breakpoint reversal sort algorithm by using three datasets. The results indicate that the proposed algorithm achieves better accuracy ratio than the previous methods.

Keywords: ant colony algorithm, edit distance, genome breakpoint, genome rearrangement, reversal sort

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Authors: Zoubida Lounis, Naouel Boumesla, Abd El Kader Bengueddach

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The main objective of this study is to synthesize a composite materials by direct synthesis at atmospheric pression having the MFI structure and MCM-41 by using double structuring. In the first part of this work we are interested in the study of the synthesis parameters, in addition to temperature, the crystallization time and pH. The second part of this work is to vary the ratio of the concentrations of both structuring C9 [C9H19(CH3)3NBr] and C16 [C16H33(CH3)3NBr] and determining the area of formation of the two materials (microporous and mesoporous at same time), for this reason we performed a battery of experiments ranging from 0 to 100% for both structural. To enhance the economic purposes of this study, the experiments were carried out by using very cheap and simple process, the pyrex tubes were used instead of the reactors, and the synthesis were done at atmospheric pressure and moderate temperature. The final products (composite materials) were obtained at high and pure quality.

Keywords: composite materials, syntheisis, catalysts, mesoporous materials, microporous materials

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Authors: J. E. Oti, J. M. Kinuthia, R. Robinson, P. Davies

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In this study, The Compressive strength of concretes made with Ground Granulated Blast furnace Slag (GGBS), pulverised Fuel Ash (PFA), rice Husk Ash (RHA) and Waste Glass Powder (WGP) after they were exposed 7800C (exposure duration of around 60 minutes) and then allowed to cool down gradually in the furnace for about 280 minutes at water binder ratio of 0.50 was investigated. GGBS, PFA, RHA and WGP were used to replace up to 20% Portland cement in the control concrete. Test for the determination of workability, compressive strength and tensile splitting strength of the concretes were carried out and the results were compared with control concrete. The test results showed that the compressive strength decreased by an average of around 30% after the concretes were exposed to the heating and cooling scenario.

Keywords: concrete, heating, cooling, pulverised fuel ash, rice husk ash, waste glass powder, GGBS, workability

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Authors: Chia-Ling Chang, Hao-Bo Chang

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Global climate change alters rainfall characteristics, while the variation of these characteristics further influences environmental conditions, such as hydrologic responses, landslide areas, and the amounts of diffuse pollution. The variations of environmental conditions may impact the stability of water resource systems. The objective of this study is to assess the present conditions of major water resource systems in Taiwan. The impact of climate change on each system is also discussed herein. Compared to the water resource systems in northern Taiwan, the ratio of the precipitation during the rainy season to that during the dry season has a larger increase in southern Taiwan. This variation of hydrologic condition impacts the stability of water resource systems and increases the risk of normal water supply. The findings in this work can be important references for water resource management.

Keywords: basin management, climate change, water resource system, water resource management

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Authors: Attaullah Khawaja, Amna Shabbir

Abstract:

Channel inversion is one of the simplest techniques for multiuser downlink systems with single-antenna users. In this paper regularized channel inversion under equal power constraint in the multiuser multiple input multiple output (MU-MIMO) broadcast channels has been considered. Sum capacity with plain channel inversion also known as Zero Forcing Beam Forming (ZFBF) and optimum sum capacity using Dirty Paper Coding (DPC) has also been investigated. Analysis and simulations show that regularization enhances the system performance and empower linear growth in Sum Capacity and specially work well at low signal to noise ratio (SNRs) regime.

Keywords: broadcast channel, channel inversion, multiple antenna multiple-user wireless, multiple-input multiple-output (MIMO), regularization, dirty paper coding (DPC), sum capacity

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