Search results for: combined loads

Authors: Hazha Hidayat, Shayma Ibrahim

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Folate metabolism plays a crucial role in the normal development of the neonatal central nervous system. It is regulated by MTHFR gene polymorphism. Any factors, which will affect this metabolism either by hereditary or gene mutation will lead to many mental disorders. The purpose of this study was to investigate whether MTHFR gene mutation contributes to the development of mental retardation and CP combined with mental retardation in Erbil city. DNA was isolated from the peripheral blood samples of 40 cases suffering from mental retardation (MR) and CP combined with MR were recruited, sequence the 4, 6, 7, 8 exons of the MTHFR gene were done to identify the variants. Exons were amplified by PCR technique and then sequenced according to Sanger method to show the differences with MTHFR reference sequences. We observed (14) mutations in 4, 6, 7, 8 exons in the MTHFR gene associated with Cerebral Palsy combined with mental retardation included deletion, insertion, Substitution. The current study provides additional evidence that multiple variations in the MTHFR gene are associated with mental retardation and Cerebral Palsy.

Keywords: methylenetetrahydrofolate reductase (MTHFR) gene, SNPs, homocysteine, sequencing

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Authors: Siti Nurma Hanim Hadie, Asma’ Hassan, Zul Izhar Ismail, Ahmad Fuad Abdul Rahim, Mohd. Zarawi Mat Nor, Hairul Nizam Ismail

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Anatomy is a medical subject, which contributes to high cognitive load during learning. Despite its complexity, anatomy remains as the most important basic sciences subject with high clinical relevancy. Although anatomy knowledge is required for safe practice, many medical students graduated without having sufficient knowledge. In fact, anatomy knowledge among the medical graduates was reported to be declining and this had led to various medico-legal problems. Applying cognitive load theory (CLT) in anatomy teaching particularly lecture would be able to address this issue since anatomy information is often perceived as cognitively challenging material. CLT identifies three types of loads which are intrinsic, extraneous and germane loads, which combine to form the total cognitive load. CLT describe that learning can only occur when the total cognitive load does not exceed human working memory capacity. Hence, managing these three types of loads with the aim of optimizing the working memory capacity would be beneficial to the students in learning anatomy and retaining the knowledge for future application.

Keywords: cognitive load theory, intrinsic load, extraneous load, germane load

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Authors: Benalia Nadia, Bensiali Nadia, Zerzouri Noura

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This paper presents an analysis of the effects of parameters np and nq for exponential load on the transmission line voltage profile, transferred power and transmission losses for different shunt compensation size. For different values for np and nq in which active and reactive power vary with it is terminal voltages as in exponential form, variations of the load voltage for different sizes of shunt capacitors are simulated with a simple two-bus power system using Matlab SimPowerSystems Toolbox. It is observed that the compensation level is significantly affected by the voltage sensitivities of loads.

Keywords: static load model, shunt compensation, transmission system, exponentiel load model

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Authors: Ivan D. Ortega, Juan D. Castro, Alberto Pertuz, Manuel Martinez

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One of the problems considered when scientists talk about climate change is the necessity of utilizing renewable sources of energy, on this category there are many approaches to the problem, one of them is wind energy and wind turbines whose designs have frequently changed along many years trying to achieve a better overall performance on different conditions. From that situation, we get the two main types known today: Vertical and Horizontal axis wind turbines, which have acronyms VAWT and HAWT, respectively. This research aims to understand how well suited a composite material, which is still in development, made with natural origin fibers is for its implementation on vertical axis wind turbines blades under certain wind loads. The study consisted on acquiring the mechanical properties of the materials to be used which where bactris guineenis, also known as pama de lata in Colombia, and adhesive that acts as the matrix which had not been previously studied to the point required for this project. Then, a simplified 3D model of the airfoil was developed and tested under some preliminary loads using finite element analysis (FEA), these loads were acquired in the Colombian Chicamocha Canyon. Afterwards, a more realistic pressure profile was obtained using computational fluid dynamics which took into account the 3D shape of the complete blade and its rotation. Finally, the blade model was subjected to the wind loads using what is known as one way fluidstructure interaction (FSI) and its behavior analyzed to draw conclusions. The observed overall results were positive since the material behaved fairly as expected. Data suggests the material would be really useful in this kind of applications in small to medium size turbines if it is given more attention and time to develop.

Keywords: CFD, FEA, FSI, natural fiber, VAWT

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Authors: Muna Jalal Ali, Essam A. Makky, Mashitah M. Yusoff

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Objectives: The aim of this study to evaluate the antimicrobial susceptibility of combined toothpaste with medicinal plants and the relations between the commercial toothpaste to its price and the patient age as well. Materials and Methods: Oral isolates of different patients aged 3 to 60 years were obtained, purified, and tested against four different ethnomedicinal plant extracts for antimicrobial activity. A total of 10 different commercial toothpastes (different brands and prices) were collected from the market, and the combined action of the medicinal plants and toothpaste was studied. Results: We found a higher bacterial population in the age group of 3–40 years than the group of 40–60 years, with approximately 44% and 32%, respectively. The combined action of ethanolic extract (alone) against oral isolates showed a synergistic effect, with 32.20, 30.50, and 25.42% for combinations A (Ci/Ca), B (Ci/Ca/P), and C (Ci/Ca/P/N), respectively. By contrast, the combined action of ethnomedicinal plants with 10 different toothpastes improved the antimicrobial sensitivity by 60, 100, and 0% for combinations A, B, and C respectively. Clinical relevance: The ethanolic extract of only combinations A and B with commercial toothpaste showed high antibacterial activity against oral isolates and the effectiveness of toothpaste is not related to the price.

Keywords: microbial evolution, oral isolates, ethnomedicinal plants, antimicrobial activity, toothpaste

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Authors: Wangxu Xia

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BACKGROUND BI-RADS 4 lesions raise the possibility of malignancy that warrant further clinical and radiologic work-up. This study aimed to evaluate the predictive performance of diffusion-weighted imaging(DWI) and microcalcifications on mammography for predicting malignancy of BI-RADS 4 lesions. In addition, the predictive performance of DWI combined with microcalcifications was alsocompared with the Kaiser score. METHODS During January 2021 and June 2023, 144 patients with 178 BI-RADS 4 lesions underwent conventional MRI, DWI, and mammography were included. The lesions were dichotomized intobenign or malignant according to the pathological results from core needle biopsy or surgical mastectomy. DWI was performed with a b value of 0 and 800s/mm2 and analyzed using theapparent diffusion coefficient, and a Kaiser score > 4 was considered to suggest malignancy. Thediagnostic performances for various diagnostic tests were evaluated with the receiver-operatingcharacteristic (ROC) curve. RESULTS The area under the curve (AUC) for DWI was significantly higher than that of the of mammography (0.86 vs 0.71, P<0.001), but was comparable with that of the Kaiser score (0.86 vs 0.84, P=0.58). However, the AUC for DWI combined with mammography was significantly highthan that of the Kaiser score (0.93 vs 0.84, P=0.007). The sensitivity for discriminating malignant from benign BI-RADS 4 lesions was highest at 89% for Kaiser score, but the highest specificity of 83% can be achieved with DWI combined with mammography. CONCLUSION DWI combined with microcalcifications on mammography could discriminate malignant BI-RADS4 lesions from benign ones with a high AUC and specificity. However, Kaiser score had a better sensitivity for discrimination.

Keywords: MRI, DWI, mammography, breast disease

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Authors: Mohammad Soltani, Ayoub Saeidi, Nikoo Khosravi, Hanieh Nohbaradar, Seyedeh Parya Barzanjeh, Hassane Zouhal

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Exercise training and herbs supplement represent have role in the treatment for patients with type 2 diabetes (T2D). However, it is unclear combined effects of exercise training and herbs supplements on diabetic risk markers. This study aimed to determine the effect of 12 weeks of combined exercise and broccoli supplementation on decitin-1 and insulin resistance in men with type 2 diabetes. Forty-four type 2 diabetes men (age, 48.52 ± 4.36) were randomly allocated to training -supplement (TS, n = 11), training- placebo (TP, n = 11), supplement (S, n = 11) and control- placebo (CP, n = 11) groups. The combined exercise program included 12 weeks, three sessions per week, that each session contained 45 minutes of resistance training with intensity 60-70% of one maximal repetition and 30 minutes aerobic training (running) with intensity 60-70% of maximum heart rate. In addition supplement groups consumed 10 grams of Broccoli per day for 12 weeks. Plasma Decitin-1, HOMA-IR, Insulin, glucose and body composition were assessed before and after training. Plasma Dectin-1, HOMA-IR, glucose and BMI significantly decreased in TS, TP and S groups compared with CP group (P < .05). In addition Insulin and skeletal muscles mass showed significant increase in TS and TP groups compared with S and CP groups (P < .05). It is concluded that both combined exercise training (aerobic-resistance) or broccoli supplement can improve plasma Decitin-1 and insulin resistance in two diabetic patients however combine of exercise training and broccoli supplement have more effective on these markers.

Keywords: broccoli supplements, combined training, decitin-1, insulin resistance, type 2 diabetes

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Authors: P. Chantarawitoon, H. Askarinejad

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

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

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Authors: Ala Abobakr Abdulhafidh Al-Dubai

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Bone loss has risen due to fractures, surgeries, and traumatic injuries. Scientists and engineers have worked over the years to find solutions to heal and accelerate bone regeneration. The bone grafting technique has been utilized, which projects significant improvement in the bone regeneration area. An extensive study is essential on the relation between the mechanical properties of bone scaffolds and the pore size of the scaffolds, as well as the relation between the mechanical properties of bone scaffolds with the development of bioactive coating on the scaffolds. In reducing the cost and time, a mechanical simulation analysis is beneficial to simulate both relations. Therefore, this study highlights the simulated mechanical analyses on three-dimensional (3D) polylactic acid (PLA) scaffolds at two different pore sizes (P: 400 and 600 μm) and two different internals distances of (D: 600 and 900 μm), with and without the presence of hydroxyapatite (HA) coating. The 3D scaffold models were designed using SOLIDWORKS software. The respective material properties were assigned with the fixation of boundary conditions on the meshed 3D models. Two different loads were applied on the PLA scaffolds, including side loads of 200 N and vertical loads of 2 kN. While only vertical loads of 2 kN were applied on the HA coated PLA scaffolds. The PLA scaffold P600D900, which has the largest pore size and maximum internal distance, generated the minimum stress under the applied vertical load. However, that same scaffold became weaker under the applied side load due to the high construction gap between the pores. The development of HA coating on top of the PLA scaffolds induced greater stress generation compared to the non-coated scaffolds which is tailorable for bone implantation. This study concludes that the pore size and the construction of HA coating on bone scaffolds affect the mechanical strength of the bone scaffolds.

Keywords: hydroxyapatite coating, bone scaffold, mechanical simulation, three-dimensional (3D), polylactic acid (PLA).

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Authors: K. A. Ramesh

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Purpose: The study is to find out the effect of isolated and combined aerobic and anaerobic interval training on stride length and stride frequency of Soccer players. Method(s): To achieve this purpose, 45 women Soccer players who participated in the Anna University, Tamilnadu, India. Intercollegiate Tournament was selected as subjects and were randomly divided into three equal groups of fifteen each, such as an anaerobic interval training group (group-I), anaerobic interval training group (group-II) and combined aerobic-anaerobic interval training group (group-III). The training program was conducted three days per weeks for a period of six weeks. Stride length and Stride frequency was selected as dependent variables. All the subjects of the three groups were tested on selected criterion variables at prior to and immediately after the training program. The concepts of dependent test were employed to find out the significant improvement due to the influence of training programs on all the selected criterion variables. The analysis of covariance (ANCOVA) was also used to analyze the significant difference, if, any among the experimental groups. Result(s): The result of the study revealed that combined group was higher than aerobic interval training and anaerobic interval training groups. Conclusion(s): It was concluded that when experimental groups were compared with each other, the combined aerobic – anaerobic interval training program was found to be greater than the aerobic and the anaerobic interval training programs on the development of stride length and stride frequency. High intensity, combined aerobic – anaerobic interval training program can be carried out in a more soccer specific way than plain running.

Keywords: stride length, stride frequency, interval training, soccer

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Authors: M. S. Belashov, A. V. Benin, Lin Hong, Sh. Sh. Nazarova, O. B. Sabirova, A. M. Uzdin, Lin Hong

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The features of calculating structures for the action of weak earthquakes are analyzed. Earthquakes with a recurrence of 30 years and 50 years are considered. In the first case, the structure is to operate normally without damage after the earthquake. In the second case, damages are allowed that do not affect the possibility of the structure operation. Three issues are emphasized: setting elastic and damping characteristics of reinforced concrete, formalization of limit states, and combinations of loads. The dependence of damping on the reinforcement coefficient is estimated. When evaluating limit states, in addition to calculations for crack resistance and strength, a human factor, i.e., the possibility of panic among people, was considered. To avoid it, it is proposed to limit a floor-by-floor speed level in certain octave ranges. Proposals have been developed for estimating the coefficients of the combination of various loads with the seismic one. As an example, coefficients of combinations of seismic and ice loads are estimated. It is shown that for strong actions, the combination coefficients for different regions turn out to be close, while for weak actions, they may differ.

Keywords: weak earthquake, frequent earthquake, damage, limit state, reinforcement, crack resistance, strength resistance, a floor-by-floor velocity, combination coefficients

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Authors: Luis Amador Jimenez, Md. Shohel Amin

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Pavement performance models are based on projections of observed traffic loads, which makes uncertain to study funding strategies in the long run if history does not repeat. Neural networks can be used to estimate deterioration rates but the learning rate and momentum have not been properly investigated, in addition, economic evolvement could change traffic flows. This study addresses both issues through a case study for roads of Montreal that simulates traffic for a period of 50 years and deals with the measurement error of the pavement deterioration model. Travel demand models are applied to simulate annual average daily traffic (AADT) every 5 years. Accumulated equivalent single axle loads (ESALs) are calculated from the predicted AADT and locally observed truck distributions combined with truck factors. A back propagation Neural Network (BPN) method with a Generalized Delta Rule (GDR) learning algorithm is applied to estimate pavement deterioration models capable of overcoming measurement errors. Linear programming of lifecycle optimization is applied to identify M&R strategies that ensure good pavement condition while minimizing the budget. It was found that CAD 150 million is the minimum annual budget to good condition for arterial and local roads in Montreal. Montreal drivers prefer the use of public transportation for work and education purposes. Vehicle traffic is expected to double within 50 years, ESALS are expected to double the number of ESALs every 15 years. Roads in the island of Montreal need to undergo a stabilization period for about 25 years, a steady state seems to be reached after.

Keywords: pavement management system, traffic simulation, backpropagation neural network, performance modeling, measurement errors, linear programming, lifecycle optimization

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Authors: Abdulsalam A. Al-Tamimi, Chris Peach, Paulo Rui Fernandes, Paulo J. Bartolo

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Bone fixation implants currently used to treat traumatic fractured bones and to promote fracture healing are built with biocompatible metallic materials such as stainless steel, cobalt chromium and titanium and its alloys (e.g., CoCrMo and Ti6Al4V). The noticeable stiffness mismatch between current metallic implants and host bone associates with negative outcomes such as stress shielding which causes bone loss and implant loosening leading to deficient fracture treatment. This paper, part of a major research program to design the next generation of bone fixation implants, describes the combined use of three-dimensional (3D) topology optimization (TO) and additive manufacturing powder bed technology (Electron Beam Melting) to redesign and fabricate the plates based on the current standard one (i.e., locking compression plate). Topology optimization is applied with an objective function to maximize the stiffness and constraint by volume reductions (i.e., 25-75%) in order to obtain optimized implant designs with reduced stress shielding phenomenon, under different boundary conditions (i.e., tension, bending, torsion and combined loads). The stiffness of the original and optimised plates are assessed through a finite-element study. The TO results showed actual reduction in the stiffness for most of the plates due to the critical values of volume reduction. Additionally, the optimized plates fabricated using powder bed techniques proved that the integration between the TO and additive manufacturing presents the capability of producing stiff reduced plates with acceptable tolerances.

Keywords: additive manufacturing, locking compression plate, finite element, topology optimization

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Authors: A. El Amri, M. El Yakhloufi Haddou, A. Khamlichi

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The numerical simulation based on the Finite Element Method (FEM) is widely used in academic institutes and in the industry. It is a useful tool to predict many phenomena present in the classical manufacturing forming processes such as fracture. But, the results of such numerical model depend strongly on the parameters of the constitutive behavior model. The influences of thermal and mechanical loads cause damage. The temperature and strain rate dependent materials’ properties and their modelling are discussed. A Johnson-Cook Model of damage has been selected for the numerical simulations. Virtual software called the ABAQUS 6.11 is used for finite element analysis. This model was introduced in order to give information concerning crack initiation during thermal and mechanical loads.

Keywords: thermo-mechanical fatigue, failure, numerical simulation, fracture, damage

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Authors: Mokhtar Bouazza

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In this paper, the simplified theory will be used to predict the thermoelastic buckling behavior of rectangular functionally graded plates. The material properties of the functionally graded plates are assumed to vary continuously through the thickness, according to a simple power law distribution of the volume fraction of the constituents. The simplified theory is used to obtain the buckling of the plate under different types of thermal loads. The thermal loads are assumed to be uniform, linear, and non-linear distribution through the thickness. Additional numerical results are presented for FGM plates that show the effects of various parameters on thermal buckling response.

Keywords: buckling, functionally graded, plate, simplified higher-order deformation theory, thermal loading

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Authors: W. S. Lawal, T. Akande

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Abstract— Four (4) difference methods were employed to detoxify Jatropha carcas, they were physical method (it include soaking and sun drying) Chemical (the use of methylated sprit, hexane and methane). Biological (the use of Aspergillus niger and then sundry for 7days and then Bacillus lichiformis) and Combined method (the combination of chemical and biological methods). Phobol esther analysis was carried out after the detoxification methods and it was found that the combined method is better off (P<0.05). Detoxified Jatropha from each of this methods was sundry and grinded for easy inclusion into poultry feed, detoxified jatropha was included at 0%, 0.5%, 1%, 2%, 3%, 4%, and 5% but the combined method was increased up to 7% because the birds were able to tolerate it, the 0% was the control experiment. 405 day old broiler chicks was used to test the effect of detoxified Jatropha carcas on their performance, there are 5birds per treatment and there are 3 replicates, the experiment lasted for 8weeks,highest number of mortality was obtained in physical method, birds in chemical method tolerated up to 3% Jatropha carcas, biological method is better, as birds there were comfortable at 5% but the best of them is combined method the birds did very well at 7% as there were less mortality and highest weight gain was achieved here (P<0.05) and it was recommended.

Keywords: phobol esther, inclusion level, tolerance level, Jatropha carcas

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Authors: Agord M. Pinto Jr., Yuzo Iano, Leandro T. Manera, Raphael R. N. Souza

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This paper describes an optimization tool-based design strategy for a Current Mode Logic CML divide-by-2 circuit. Representing a building block for output frequency generation in a RFID protocol based-frequency synthesizer, the circuit was designed to minimize the power consumption for driving of multiple loads with unbalancing (at transceiver level). Implemented with XFAB XC08 180 nm technology, the circuit was optimized through MunEDA WiCkeD tool at Cadence Virtuoso Analog Design Environment ADE.

Keywords: divide-by-2 circuit, CMOS technology, PLL phase locked-loop, optimization tool, CML current mode logic, RF transceiver

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Authors: Lian Song, Shao-Bo Kang, Bo Yang

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Concrete filled steel tubular (CFST) structure has been widely used in construction practices due to its superior performances under various loading conditions. However, limited studies are available when this type of structure is subjected to impact or explosive loads. Current methods in relevant design codes are not specific for preventing progressive collapse of CFST structures. Therefore, it is necessary to carry out numerical simulations on CFST structure under impact loads. In this study, finite element analyses are conducted on the mechanical behaviour of composite frames which composed of CFST columns and steel beams subject to impact loading. In the model, CFST columns are simulated using finite element software ABAQUS. The model is verified by test results of solid and hollow CFST columns under lateral impacts, and reasonably good agreement is obtained through comparisons. Thereafter, a multi-scale finite element modelling technique is developed to evaluate the behaviour of a five-storey three-span planar composite frame. Alternate path method and direct simulation method are adopted to perform the dynamic response of the frame when a supporting column is removed suddenly. In the former method, the reason for column removal is not considered and only the remaining frame is simulated, whereas in the latter, a specific impact load is applied to the frame to take account of the column failure induced by vehicle impact. Comparisons are made between these two methods in terms of displacement history and internal force redistribution, and design recommendations are provided for the design of CFST structures under impact loads.

Keywords: planar composite frame, collapse analysis, impact loading, direct simulation method, alternate path method

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Authors: B. S. Jayashankarbabu, Karisiddappa

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The finite element method is used to obtain the elastic buckling load factor for square isotropic plate containing circular, square and rectangular cutouts. ANSYS commercial finite element software had been used in the study. The applied inplane loads considered are uniaxial and biaxial compressions. In all the cases the load is distributed uniformly along the plate outer edges. The effects of the size and shape of concentric cutouts with different plate thickness ratios and the influence of plate edge condition, such as SSSS, CCCC and mixed boundary condition SCSC on the plate buckling strength have been considered in the analysis.

Keywords: concentric cutout, elastic buckling, finite element method, inplane loads, thickness ratio

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Authors: O. Arikan, C. Kocatepe, G. Ucar, Y. Hacialiefendioglu

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In this paper, influence of harmonics on medium voltage distribution system of Bogazici Electricity Distribution Inc. (BEDAS) which takes place at Istanbul/Turkey is investigated. A ring network consisting of residential loads is taken into account for this study. Real system parameters and measurement results are used for simulations. Also, probable working conditions of the system are analyzed for %50, %75 and %100 loading of transformers with similar harmonic contents. Results of the study are exhibited the influence of nonlinear loads on %THDV, P.F. and technical losses of the medium voltage distribution system.

Keywords: distribution system, harmonic, technical losses, power factor, total harmonic distortion, residential load, medium voltage

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Authors: Ahmed Elsebaay, Maged A. Abu Adma, Mahmoud Ramadan

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This study presents a technique clarifying the effect of ambient air temperature and loads power factor changing from standard values on electric generator power rating. The study introduces an optimized technique for selecting the correct electric generator power rating for certain application and operating site ambient temperature. The de-rating factors due to the previous effects will be calculated to be applied on a generator to select its power rating accurately to avoid unsafe operation and save its lifetime. The information in this paper provides a simple, accurate, and general method for synchronous generator selection and eliminates common errors.

Keywords: ambient temperature, de-rating factor, electric generator, power factor

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Authors: Boukari Nassim

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This paper describes the use of odd pair autoregressive coefficients (Yule _Walker and Burg) for the feature extraction of electroencephalogram (EEG) signals. In the classification: the radial basis function neural network neural network (RBFNN) is employed. The RBFNN is described by his architecture and his characteristics: as the RBF is defined by the spread which is modified for improving the results of the classification. Five types of EEG signals are defined for this work: Set A, Set B for normal signals, Set C, Set D for interictal signals, set E for ictal signal (we can found that in Bonn university). In outputs, two classes are given (AC, AD, AE, BC, BD, BE, CE, DE), the best accuracy is calculated at 99% for the combined odd pair autoregressive coefficients. Our method is very effective for the diagnosis of epileptic EEG signals.

Keywords: epilepsy, EEG signals classification, combined odd pair autoregressive coefficients, radial basis function neural network

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Authors: A. Jomartov, A. Tuleshov, B. Tultaev

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One of the main tasks in the development of textile machinery is to increase the rapidity of automatic looms, and consequently, their productivity. With increasing automatic loom speeds, the dynamic loads on their separate mechanisms and moving joints sharply increase. Dynamic research allows us to determine the weakest mechanisms of the automatic loom. The modern automatic loom consists of a large number of structurally different mechanisms. These are cam, lever, gear, friction and combined cyclic mechanisms. The modern automatic loom contains various mechatronic devices: A device for the automatic removal of faulty weft, electromechanical drive warp yarns, electronic controllers, servos, etc. In the paper, we consider the multibody dynamic model of the automatic loom on the software complex SimulationX. SimulationX is multidisciplinary software for modeling complex physical and technical facilities and systems. The multibody dynamic model of the automatic loom allows consideration of: The transition processes, backlash at the joints and nodes, the force of resistance and electric motor performance.

Keywords: automatic loom, dynamics, model, multibody, SimulationX

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Authors: Ashkan Zargar, Ali Taheri Mirghaed, Zein Talal Barakat, Alireza Khosravi, Hamed Paknejad

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With the increase of bacterial resistance to the chemical antibiotics, replacing it with ecofriendly herbal materials and with no adverse effects in the host body is very important. Therefore, in this study, the effect of combined essential oil (Thymus vulgaris-Origanum magorana and Ziziphora clinopodioides) on the growth behavior of Yersinia ruckeri, Aeromonas hydrophila and Lactococcus garvieae was evaluated. The compositions of the herbal essential oils used in this study were determined by gas chromatography-mass spectrometry (GC-MS) while, the investigating of antimicrobial effects was conducted by the agar-disc diffusion method, determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), and bacterial growth curves determination relied on optical density (OD) at 630 nm. The main compounds were thymol (40.60 %) and limonene (15.98 %) for Thymus vulgaris while carvacrol (57.86 %) and thymol (13.54 %) were the major compounds in Origanum magorana. As regards Ziziphora clinopodiodes, α-pinene (22.6 %) and carvacrol (21.1 %) represented the major constituents. Concerning Yersinia ruckeri, disc-diffusion results showed that t.O.z (50 % Origanum majorana) combined essential oil was presented the best inhibition zone (30.66 mm) but it was exhibited no significant differences with other tested commercial antibiotics except oxytetracycline (P <0/05). The inhibitory activity and the bactericidal effect of the t.O.z, unveiled by the MIC= 0.2 μL /mL and MBC= 1.6 μL /mL values, were clearly the best between all combined oils. The growth behaviour of Yersinia ruckeri was affected by this combined essential oil and changes in temperature and pH conditions affected herbal oil performance. As regard Aeromonas hydrophila, its results were so similar to Yersinia ruckeri results and t.O.z (50 % Origanum majorana) was the best between all combined oils (inhibition zone= 26 mm, MIC= 0.4 μL /mL and MBC= 3.2 μL /mL, combined essential oil was affected bacterial growth behavior). Also for Lactococcus garvieae, t.O.z (50 % Origanum majorana) was the best between all combined oils having the best inhibition zone= 20.66 mm, MIC= 0.8 μL /mL and MBC= 1.6 μL /mL and best effect on inhibiting bacterial growth. Combined herbal essential oils have a good and noticeable effect on the growth behavior of pathogenic bacteria in the laboratory, and by continuing research in the host, they may be a suitable alternative to control, prevent and treat diseases caused by these bacteria.

Keywords: bacterial pathogen, herbal medicine, growth behavior, fish

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Authors: Phyo Wai Aung, Sysoev Oleg Evgenevich, Boris Necolavet Maryin

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The article deals with theoretical problems of correlation of processes of microstructure changes of structural materials under cyclic loading and acoustic emission. The ways of the evolution of a microstructure under the influence of cyclic loading are shown depending on the structure of the initial crystal structure of the material. The spectra of the frequency characteristics of acoustic emission signals are experimentally obtained when testing titanium samples for cyclic loads. Changes in the fractal dimension of the acoustic emission signals in the selected frequency bands during the evolution of the microstructure of structural materials from the action of cyclic loads, as well as in the destruction of samples, are studied. The experimental samples were made of VT-20 structural material widely used in aircraft and rocket engineering. The article shows the striving of structural materials for synergistic stability and reduction of the fractal dimension of acoustic emission signals, in accordance with the degradation of the microstructure, which occurs as a result of fatigue processes from the action of low cycle loads. As a result of the research, the frequency range of acoustic emission signals of 100-270 kHz is determined, in which the fractal dimension of the signals, it is possible to most reliably predict the durability of structural materials.

Keywords: cyclic loadings, material structure changing, acoustic emission, fractal dimension

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Authors: M. Inmaculada Alvarez-Fernández, Celestino González-Nicieza, M. Belén Prendes-Gero, Fernando López-Gayarre

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Among many factors affecting the stability of mining excavations, rock-bursts and tremors play a special role. These dynamic loads occur practically always and have different sources of generation. The most important of them is the commonly used mining technique, which disintegrates a certain area of the rock mass not only in the area of the planned mining, but also creates waves that significantly exceed this area affecting the structural elements. In this work it is analysed the consequences of dynamic loads over the structural elements in an underground room and pillar mine to avoid roof instabilities. With this end, dynamic loads were evaluated through in situ and laboratory tests and simulated with numerical modelling. Initially, the geotechnical characterization of all materials was carried out by mean of large-scale tests. Then, drill holes were done on the roof of the mine and were monitored to determine possible discontinuities in it. Three seismic stations and a triaxial accelerometer were employed to measure the vibrations from blasting tests, establish the dynamic behaviour of roof and pillars and develop the transmission laws. At last, computer simulations by FLAC3D software were done to check the effect of vibrations on the stability of the roofs. The study shows that in-situ tests have a greater reliability than laboratory samples because of eliminating the effect of heterogeneities, that the pillars work decreasing the amplitude of the vibration around them, and that the tensile strength of a beam and depending on its span is overcome with waves in phase and delayed. The obtained transmission law allows designing a blasting which guarantees safety and prevents the risk of future failures.

Keywords: dynamic modelling, long term instability risks, room and pillar, seismic collapse

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Authors: Jairo Aparecido Martins, Estaner Claro Romão

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This paper presents the static and cyclic stresses in combination with fatigue analysis resultant of loads applied on the friction discs usually utilized on industrial clutches. The material chosen to simulate the friction discs under load is aluminum. The numerical simulation was done by software COMSOL^TM Multiphysics. The results obtained for static loads showed enough stiffness for both geometries and the material utilized. On the other hand, in the fatigue standpoint, failure is clearly verified, what demonstrates the importance of both approaches, mainly dynamical analysis. The results and the conclusion are based on the stresses on disc, counted stress cycles, and fatigue usage factor.

Keywords: aluminum, industrial clutch, static and dynamic loading, numerical simulation

Procedia PDF Downloads 167

Authors: Rasheed A. Adebayo, Mehluli M. Moyo, Ignatius V. Nsahlai

Abstract:

Ruminants are known to relish roughage for productivity but the effect of its quality on digesta load in rumen, omasum, abomasum and other distal organs of the digestive tract is yet unknown. Reticulorumen fill is a strong indicator for long-term control of intake in ruminants. As such, the measurement and prediction of digesta load in these compartments may be crucial to productivity in the ruminant industry. The current study aimed at determining the effect of (a) diet quality on digesta load in digestive organs of goats, and (b) period of meal termination on the reticulorumen fill and digesta load in other distal compartments of the digestive tract of goats. Goats were fed with urea-treated hay (UTH), urea-sprayed hay (USH) and non-treated hay (NTH). At the end of eight weeks of a feeding trial period, upon termination of a meal in the morning, afternoon or evening, all goats were slaughtered in random groups of three per day to measure reticulorumen fill and digesta loads in other distal compartments of the digestive tract. Both diet quality and period affected (P < 0.05) the measure of reticulorumen fill. However, reticulorumen fill in the evening was larger (P < 0.05) than afternoon, while afternoon was similar (P > 0.05) to morning. Also, diet quality affected (P < 0.05) the wet omasal digesta load, wet abomasum, dry abomasum and dry caecum digesta loads but did not affect (P > 0.05) both wet and dry digesta loads in other compartments of the digestive tract. Period of measurement did not affect (P > 0.05) the wet omasal digesta load, and both wet and dry digesta loads in other compartments of the digestive tract except wet abomasum digesta load (P < 0.05) and dry caecum digesta load (P < 0.05). Both wet and dry reticulorumen fill were correlated (P < 0.05) with omasum (r = 0.623) and (r = 0.723), respectively. In conclusion, reticulorumen fill of goats decreased by improving the roughage quality; and the period of meal termination and measurement of the fill is a key factor to the quantity of digesta load.

Keywords: digesta, goats, meal termination, reticulo-rumen fill

Procedia PDF Downloads 353

Authors: A. A. Azemati, H. Hosseini

Abstract:

By using an adequate paint in buildings, energy consumption can be decreased. In this research, a range of wall paints in different climatic conditions has been investigated to observe its effect on energy consumption. In the current study, the researchers have investigated the effect of different parameters including climatic condition, absorption coefficient, and thermal loads on paint coating. In order to study these effects, heating and cooling loads of a typical building with different color paints have been calculated. The effect of building paint in different climatic condition was studied and a comparison was drawn between paints and painting coats with inorganic micro particles in temperate climate to obtain optimized energy consumption.

Keywords: climate, energy consumption, inorganic, painting coats

Procedia PDF Downloads 270

Authors: Saltanat Zhilkibayeva, Muratulla Utenov, Nurzhan Utenov

Abstract:

The distributed inertia forces of complex nature appear in links of rod mechanisms within the motion process. Such loads raise a number of problems, as the problems of destruction caused by a large force of inertia; elastic deformation of the mechanism can be considerable, that can bring the mechanism out of action. In this work, a new analytical approach for the definition of internal forces in links of robotic systems and mechanisms with statically indeterminate and determinate structures taking into account the distributed inertial and concentrated forces is proposed. The relations between the intensity of distributed inertia forces and link weight with geometrical, physical and kinematic characteristics are determined in this work. The distribution laws of inertia forces and dead weight make it possible at each position of links to deduce the laws of distribution of internal forces along the axis of the link, in which loads are found at any point of the link. The approximation matrixes of forces of an element under the action of distributed inertia loads with the trapezoidal intensity are defined. The obtained approximation matrixes establish the dependence between the force vector in any cross-section of the element and the force vector in calculated cross-sections, as well as allow defining the physical characteristics of the element, i.e., compliance matrix of discrete elements. Hence, the compliance matrixes of an element under the action of distributed inertial loads of trapezoidal shape along the axis of the element are determined. The internal loads of each continual link are unambiguously determined by a set of internal loads in its separate cross-sections and by the approximation matrixes. Therefore, the task is reduced to the calculation of internal forces in a final number of cross-sections of elements. Consequently, it leads to a discrete model of elastic calculation of links of rod mechanisms. The discrete model of the elements of mechanisms and robotic systems and their discrete model as a whole are constructed. The dynamic equilibrium equations for the discrete model of the elements are also received in this work as well as the equilibrium equations of the pin and rigid joints expressed through required parameters of internal forces. Obtained systems of dynamic equilibrium equations are sufficient for the definition of internal forces in links of mechanisms, which structure is statically definable. For determination of internal forces of statically indeterminate mechanisms (in the way of determination of internal forces), it is necessary to build a compliance matrix for the entire discrete model of the rod mechanism, that is reached in this work. As a result by means of developed technique the programs in the MAPLE18 system are made and animations of the motion of the fourth class mechanisms of statically determinate and statically indeterminate structures with construction on links the intensity of cross and axial distributed inertial loads, the bending moments, cross and axial forces, depending on kinematic characteristics of links are obtained.

Keywords: distributed inertial forces, internal forces, statically determinate mechanisms, statically indeterminate mechanisms

Procedia PDF Downloads 202