Search results for: fixed parameters

Authors: Hatem Ghith

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This research paper experimentally investigates the effect of burning by fire flame from one face on the behavior and load carrying capacity for reinforced columns. Residual ultimate load carrying capacity, axial deformation, crack pattern and maximum crack width for column specimens with and without burning were recorded and discussed. Tested six reinforced concrete columns were divided into control specimen and two groups. The first group was exposed to a fire with a different temperature (300, 500, 700 °C) for an hour with reinforcement ratio 0.89% and the second group was exposed to a fire with a temperature 500 °C for an hour with different reinforcement ratio (0.89%, 2.18%, and 3.57%), then all columns were tested under short-term axial loading. From the obtained results, it could be concluded that the fire parameters significantly influence the fire resistance of R.C columns. The fire parameters cause axial deformation and moment on the column due to the eccentricity that generated from the difference in temperature and consequently the compressive stresses of both faces of the columns but the increased reinforcement ratio enhanced the resistance of columns for axial deformation and moment on the column due to the eccentricity.

Keywords: columns, reinforcement ratio, strength, time exposure

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Authors: Hyeong-Gyu Park, Hak-Gon Noh, Beom-Soo Kang, Jeong Kim

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Electromagnetic forming (EMF) process is one of a high-speed forming process, which uses an electromagnetic body (Lorentz) force to deform work-piece. Advantages of EMF are summarized as improvement of formability, reduction in wrinkling, non-contact forming. In this study, the spiral coil is considered to evaluate formability in terms of pressure distribution of the forming process. It also is represented forming results of numerical analysis using ANSYS code. In the numerical simulation, RLC circuit coupled with spiral coil was made to consider the design parameters such as system input current and electromagnetic force. The simulation results show that even though input peak currents level are same level in each case, forming condition is certainly different because of frequency of input current and magnitude of current density and magnetic flux density. Finally, the simulation results appear that electromagnetic forming force apparently affected by input current frequency which determines magnitude of current density and magnetic flux density.

Keywords: electromagnetic forming, high-speed forming, RLC circuit, Lorentz force

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Authors: Martins Gbenga., Orosun M. M., Olowookere C. J., Bamidele Lateef

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Radiation exposures from diagnostic medical examinations are almost always justified by the benefits of accurate diagnosis of possible disease conditions. The aim is to assess the influence of selected exposure parameters on scattered dose rates. The research was carried out using Gamma Scout software installation on the Computer system (Laptop) to record the radiation counts, pulse rate, and dose rate for 136 patients. Seventy-three patients participated in the male category with 53.7%, while 63 females participated with 46.3%. The mean and standard deviation value for each parameter is recorded, and tube potential is within 69.50±11.75 ranges between 52.00 and 100.00, tube current is within 23.20±17.55 ranges between 4.00 and 100.00, focus skin distance is within 73.195±33.99 and ranges between 52.00 and 100.00. Dose Rate (DRate in µSv/hr) is significant at an interval of 0.582 and 0.587 for tube potential and body thickness (cm). Tube potential is significant at an interval of 0.582 and 0.842 of DRate (µSv/hr) and body thickness (cm). The study was compared with other studies. The exposure parameters selected during each examination contributed to scattered radiation. A quality assurance program (QAP) is advised for the center.

Keywords: x-radiation, exposure rate, dose rate, tube potentials, scattered radiation, diagnostic examination

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Authors: Sanyka Banerjee, Saikat Nandi, P. K. Dan

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Synchronizers as an integral part of gearbox is a key element in the transmission system in automotive. The performance of synchronizer affects transmission efficiency and driving comfort. Synchronizing mechanism as a major component of transmission system must be capable of preventing vibration and noise in the gears. Gear shifting efficiency improvement with an aim to achieve smooth, quick and energy efficient power transmission remains a challenge for the automotive industry. Performance of the synchronizer is dependent on the features and characteristics of its sub-components and therefore analysis of the contribution of such characteristics is necessary. An important exercise involved is to identify all such characteristics or factors which are associated with the modeling and analysis and for this purpose the literature was reviewed, rather extensively, to study the mathematical models, formulated considering such. It has been observed that certain factors are rather common across models; however, there are few factors which have specifically been selected for individual models, as reported. In order to obtain a more realistic model, an attempt here has been made to identify and assimilate practically all possible factors which may be considered in formulating the model more comprehensively. A simulation study, formulated as a block model, for such analysis has been carried out in a reliable environment like MATLAB. Lower synchronization time is desirable and hence, it has been considered here as the output factors in the simulation modeling for evaluating transmission efficiency. An improved synchronizer model requires optimized values of sub-component design parameters. A parametric optimization utilizing Taguchi’s design of experiment based response data and their analysis has been carried out for this purpose. The effectiveness of the optimized parameters for the improved synchronizer performance has been validated by the simulation study of the synchronizer block model with improved parameter values as input parameters for better transmission efficiency and driver comfort.

Keywords: design of experiments, modeling, parametric optimization, simulation, synchronizer

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Authors: Raviraja Shetty G., K. G. Poojitha

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An experiment was conducted at College of Horticulture, Mudigere to study the effect of different growth regulators on seed germination and vegetative propagation by cuttings of Celastrus paniculata an endangered medicinal plant. The extracted seeds are subjected to 11 different pre-soaking treatments which include control, GA3 at 300, 350, 400ppm, KNO3 at 1.0%, 1.5%, 2.0%, H2SO4 at 0.5%, 1.0% and HCl 0.5%,1.0% for 100 seeds per treatment. Among the different germination inducing treatments, seeds treated with gibberellins responded well with high seed germination and vigorous seedling growth. The seeds treated with GA3 400 ppm recorded maximum germination and growth parameters like rate of germination, shoot length, root length, plant vigour, fresh and dry weight of which was followed GA3 350 ppm. The commencement of germination and 50 per cent germination was also earlier in the same treatment. The cuttings of C. paniculata took more time for root initiation up to four months and sprouting percent was moderate as compared to other easy to root species. Among different treatments, IBA 2000 ppm was found to be the best, which recorded the maximum shoot and also root parameters. The results of present investigation will be helpful for conservation of this endangered medicinal plant through propagation

Keywords: conservation, germination, growth, germination, propagation

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Authors: Karthick Gopalan, Selvamohan Thankiah

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Biosurfactants are lipid compounds produced by microbes, which are amphipathic molecules consisting of hydrophophic and hydrophilic domains. In the present investigation, ten bacterial strains were isolated from petroleum oil contaminated sites near petrol bunk. Oil collapsing test, haemolytic activity were used as a criteria for primary isolation of biosurfactant producing bacteria. In this study, all the bacterial strains gave positive results. Among the ten strains, two were observed as good biosurfactant producers, they utilize the diesel as a sole carbon source. Optimization of biosurfactant producing bacteria isolated from petroleum oil contaminated sites was carried out using different parameters such as, temperature (20ºC, 25ºC, 30ºC, 37ºC and 45ºC), pH (5,6,7,8 & 9) and nitrogen sources (ammonium chloride, ammonium carbonate and sodium nitrate). Biosurfactants produced by bacteria were extracted, dried and quantified. As a result of optimization of parameters the suitable values for the production of more amount of biosurfactant by the isolated bacterial species was observed as 30ºC (0.543 gm/lt) in the pH 7 (0.537 gm/lt) with ammonium nitrate (0.431 gm/lt) as sole carbon source.

Keywords: isolation and identification, biosurfactant, microorganism, bioaugmentation

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Authors: Alexander de Tomás, Miquel Sierra, Stefan Pfenninger, Francesco Lombardi, Ines Campos, Cristina Madrid

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Environmental parameters are key in the definition of sustainable energy systems yet excluded from most energy system optimization models. Still, decision-making may be misleading without considering them. Environmental analyses of the energy transition are a key part of industrial ecology but often are performed without any input from the users of the information. This work assesses the systemic impacts of energy transition pathways in Portugal. Using the Calliope energy modeling framework, 250+ optimized energy system pathways are generated. A Delphi study helps to identify the relevant criteria for the stakeholders as regards the environmental assessment, which is performed with ENBIOS, a python package that integrates life cycle assessment (LCA) with a metabolic analysis based on complex relations. Furthermore, this study focuses on how the uncertainty propagates through the model’s consortium. With the aim of doing so, a soft link between the Calliope/ENBIOS cascade and Brightway’s data capabilities is built to perform Monte Carlo simulations. These findings highlight the relevance of including uncertainty analysis as a range of values rather than informing energy transition results with a single value.

Keywords: energy transition, energy modeling, uncertainty, sustainability

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Authors: Ebrahim Mansoori, Datin Joriah Muhammad

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Recent studies in finance have focused on the effect of external variables on working capital management. This study investigates the effect of corruption indexes on firms' working capital management. A large data set that covers data from 2005 to 2013 from five ASEAN countries, namely, Malaysia, Indonesia, Singapore, Thailand, and the Philippines, was selected to investigate how the level of corruption in these countries affect working capital management. The results of panel data analysis include fixed effect estimations showed that a high level of countries' corruption indexes encourages managers to shorten the CCC length. Meanwhile, the managers reduce the level of investment in cash and cash equivalents when the levels of corruption indexes increase. Therefore, increasing the level of countries' corruption indexes encourages managers to select conservative working capital strategies by reducing the level of NLB.

Keywords: ASEAN, corruption indexes, panel data analysis, working capital management

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Authors: B. Guezzen, M.A. Didi, B. Medjahed

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A factorial design of experiments and a response surface methodology were implemented to investigate the liquid-liquid extraction process of zinc (II) from acetate medium using the 1-Butyl-imidazolium di(2-ethylhexyl) phosphate [BIm⁺][D2EHP^-]. The optimization process of extraction parameters such as the initial pH effect (2.5, 4.5, and 6.6), ionic liquid concentration (1, 5.5, and 10 mM) and salt effect (0.01, 5, and 10 mM) was carried out using a three-level full factorial design (3³). The results of the factorial design demonstrate that all these factors are statistically significant, including the square effects of pH and ionic liquid concentration. The results showed that the order of significance: IL concentration > salt effect > initial pH. Analysis of variance (ANOVA) showing high coefficient of determination (R² = 0.91) and low probability values (P < 0.05) signifies the validity of the predicted second-order quadratic model for Zn (II) extraction. The optimum conditions for the extraction of zinc (II) at the constant temperature (20 °C), initial Zn (II) concentration (1mM) and A/O ratio of unity were: initial pH (4.8), extractant concentration (9.9 mM), and NaCl concentration (8.2 mM). At the optimized condition, the metal ion could be quantitatively extracted.

Keywords: ionic liquid, response surface methodology, solvent extraction, zinc acetate

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Authors: Vanessa A. Segovia, Sonia E. Ruiz

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The use of energy dissipation systems for seismic applications has increased worldwide, thus it is necessary to develop practical and modern criteria for their optimal design. Here, a direct displacement-based seismic design approach for frame buildings with hysteretic energy dissipation systems (HEDS) is applied. The building is constituted by two individual structural systems consisting of: 1) A main elastic structural frame designed for service loads and 2) A secondary system, corresponding to the HEDS, that controls the effects of lateral loads. The procedure implies to control two design parameters: A) The stiffness ratio (α=K_frame/K_(total system)), and B) The strength ratio (γ= V_damper / V_(total system)). The proposed damage-controlled approach contributes to the design of a more sustainable and resilient building because the structural damage is concentrated on the HEDS. The reduction of the design displacement spectrum is done by means of a damping factor (recently published) for elastic structural systems with HEDS, located in Mexico City. Two limit states are verified: Serviceability and near collapse. Instead of the traditional trial-error approach, a procedure that allows the designer to establish the preliminary sizes of the structural elements of both systems is proposed. The design methodology is applied to an 8-story steel building with buckling restrained braces, located in soft soil of Mexico City. With the aim of choosing the optimal design parameters, a parametric study is developed considering different values of α and γ. The simplified methodology is for preliminary sizing, design, and evaluation of the effectiveness of HEDS, and it constitutes a modern and practical tool that enables the structural designer to select the best design parameters.

Keywords: damage-controlled buildings, direct displacement-based seismic design, optimal hysteretic energy dissipation systems, hysteretic dampers

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Authors: Rashid Ahmed , John N. Avaritsiotis

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Many signal subspace-based approaches have already been proposed for determining the fixed Direction of Arrival (DOA) of plane waves impinging on an array of sensors. Two procedures for DOA estimation based neural networks are presented. First, Principal Component Analysis (PCA) is employed to extract the maximum eigenvalue and eigenvector from signal subspace to estimate DOA. Second, minor component analysis (MCA) is a statistical method of extracting the eigenvector associated with the smallest eigenvalue of the covariance matrix. In this paper, we will modify a Minor Component Analysis (MCA(R)) learning algorithm to enhance the convergence, where a convergence is essential for MCA algorithm towards practical applications. The learning rate parameter is also presented, which ensures fast convergence of the algorithm, because it has direct effect on the convergence of the weight vector and the error level is affected by this value. MCA is performed to determine the estimated DOA. Preliminary results will be furnished to illustrate the convergences results achieved.

Keywords: Direction of Arrival, neural networks, Principle Component Analysis, Minor Component Analysis

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Authors: Cagri Memis, Muzaffer Kapanoglu

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The school bus routing problem (SBRP) is a variant of the Vehicle Routing Problem (VRP) classified as a location-allocation-routing problem. In this study, the SBRP is decomposed into two sub-problems: (1) bus route generation and (2) bus stop selection to solve large instances of the SBRP in reasonable computational times. To solve the first sub-problem, we propose a genetic algorithm to generate bus routes. Once the routes have been fixed, a sub-problem remains of allocating students to stops considering the capacity of the buses and the walkability constraints of the students. While the exact method solves small-scale problems, treating large-scale problems with the exact method becomes complex due to computational problems, a deficiency that the genetic algorithm can overcome. Results obtained from the proposed approach on 150 instances up to 250 stops show that the matheuristic algorithm provides better solutions in reasonable computational times with respect to benchmark algorithms.

Keywords: genetic algorithm, matheuristic, school bus routing problem, vehicle routing problem

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Authors: O. M. Couto Junior, I. Matos, I. M. Fonseca, P. A. Arroyo, E. A. Silva, M. A. S. D. Barros

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This study was the adsorption of paracetamol from aqueous solutions on fixed beds of activated carbon from babassy coconut shell. Several operation conditions on the shape of breakthrough curves were investigated and proposed model is successfully validated with the literature data and obtained experimental data. The initial paracetamol concentration increases from 20 to 50 mg.L-1, and the break point time decreases, tb, from 18.00 to 10.50 hours. The fraction of unused bed length, HUNB, at break-through point is obtained in the range of 1.62 to 2.81 for 20 to 50 mg.L-1 of initial paracetamol concentration. The presence of Ca+2 and Mg+2 are responsible for increasing the hardness of the water, affects significantly the adsorption kinetics, and lower removal efficiency by adsorption of paracetamol on activated carbons. The axial dispersion coefficients, DL, was constants for concentrated feed solution, but this parameter has different values for deionized and hardness water. The mass transfer coefficient, Ks, was increasing with concentrated feed solution.

Keywords: paracetamol, adsorption, water hardness, activated carbon.

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Authors: Ece Cigdem Mutlu, Burak Alakent

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Maintaining the quality of manufactured products at a desired level depends on the stability of process dispersion and location parameters and detection of perturbations in these parameters as promptly as possible. Shewhart control chart is the most widely used technique in statistical process monitoring to monitor the quality of products and control process mean and variability. In the application of Xbar control charts, sample standard deviation and sample mean are known to be the most efficient conventional estimators in determining process dispersion and location parameters, respectively, based on the assumption of independent and normally distributed datasets. On the other hand, there is no guarantee that the real-world data would be normally distributed. In the cases of estimated process parameters from Phase I data clouded with outliers, efficiency of traditional estimators is significantly reduced, and performance of Xbar charts are undesirably low, e.g. occasional outliers in the rational subgroups in Phase I data set may considerably affect the sample mean and standard deviation, resulting a serious delay in detection of inferior products in Phase II. For more efficient application of control charts, it is required to use robust estimators against contaminations, which may exist in Phase I. In the current study, we present a simple approach to construct robust Xbar control charts using average distance to the median, Qn-estimator of scale, M-estimator of scale with logistic psi-function in the estimation of process dispersion parameter, and Harrell-Davis qth quantile estimator, Hodge-Lehmann estimator and M-estimator of location with Huber psi-function and logistic psi-function in the estimation of process location parameter. Phase I efficiency of proposed estimators and Phase II performance of Xbar charts constructed from these estimators are compared with the conventional mean and standard deviation statistics both under normality and against diffuse-localized and symmetric-asymmetric contaminations using 50,000 Monte Carlo simulations on MATLAB. Consequently, it is found that robust estimators yield parameter estimates with higher efficiency against all types of contaminations, and Xbar charts constructed using robust estimators have higher power in detecting disturbances, compared to conventional methods. Additionally, utilizing individuals charts to screen outlier subgroups and employing different combination of dispersion and location estimators on subgroups and individual observations are found to improve the performance of Xbar charts.

Keywords: average run length, M-estimators, quality control, robust estimators

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Authors: Jonathan Heng, Yoong Cheah Huei

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A strategic model that does not trigger any false alarms to detect anomalies in Secure Water Treatment (SWaT) test bed is presented. This model uses machine learning invariants formulated from streamlining the general form of Auto-Regressive models with eXogenous input. A creative generalized CUSUM algorithm to integrate the invariants and the detection strategy technique is successfully developed and tested in the SWaT Programmable Logic Controllers (PLCs). Three steps to fine-tune parameters, b and τ in the generalized algorithm are stated and an example used to demonstrate the tuning process is discussed. This approach can swiftly and effectively detect various scopes of cyber-attacks such as multiple points single stage and multiple points multiple stages in SWaT. This technique can be applied in water treatment plants and other cyber physical systems like power and gas plants too.

Keywords: machine learning invariants, generalized CUSUM algorithm with invariants and detection strategy, scope of cyber attacks, strategic model, tuning parameters

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Authors: Mahdieh Khalilinezhad, Silvana Dellepiane, Gianni Vernazza

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The aim of the present work is to build a model based on tissue characterization that is able to discriminate pathological and non-pathological regions from three-phasic CT images. Based on feature selection in different phases, in this research, we design a neural network system that has optimal neuron number in a hidden layer. Our approach consists of three steps: feature selection, feature reduction, and classification. For each ROI, 6 distinct set of texture features are extracted such as first order histogram parameters, absolute gradient, run-length matrix, co-occurrence matrix, autoregressive model, and wavelet, for a total of 270 texture features. We show that with the injection of liquid and the analysis of more phases the high relevant features in each region changed. Our results show that for detecting HCC tumor phase3 is the best one in most of the features that we apply to the classification algorithm. The percentage of detection between these two classes according to our method, relates to first order histogram parameters with the accuracy of 85% in phase 1, 95% phase 2, and 95% in phase 3.

Keywords: multi-phasic liver images, texture analysis, neural network, hidden layer

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Authors: Bader Eddin Al Asali, N. Srinivasa Reddy

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Cities are dynamic in nature and are characterized by concentration of people, infrastructure, services and markets, which offer opportunities for production and consumption. Often growth and development in urban areas is not systematic, and is directed by number of factors like natural growth, land prices, housing availability, job locations-the central business district (CBD’s), transportation routes, distribution of resources, geographical boundaries, administrative policies, etc. One sided spatial and geographical development in cities leads to the unequal spatial distribution of population and jobs, resulting in high transportation activity. City development can be measured by the parameters such as urban size, urban form, urban shape, and urban structure. Urban Size is the city size and defined by the population of the city, and urban form is the location and size of the economic activity (CBD) over the geographical space. Urban shape is the geometrical shape of the city over which the distribution of population and economic activity occupied. And Urban Structure is the transport network within which the population and activity centers are connected by hierarchy of roads. Among the urban land-use systems transportation plays significant role and is one of the largest energy consuming sector. Transportation interaction among the land uses is measured in Passenger-Km and mean trip length, and is often used as a proxy for measurement of energy consumption in transportation sector. Among the trips generated in cities, work trips constitute more than 70 percent. Work trips are originated from the place of residence and destination to the place of employment. To understand the role of urban parameters on transportation interaction, theoretical cities of different size and urban specifications are generated through building block exercise using a specially developed interactive C++ programme and land use transportation modeling is carried. The land-use transportation modeling exercise helps in understanding the role of urban parameters and also to classify the cities for their urban form, structure, and shape. Muscat the capital city of Oman underwent rapid urbanization over the last four decades is taken as a case study for its classification. Also, a pilot survey is carried to capture urban travel characteristics. Analysis of land-use transportation modeling with field data classified Muscat as a linear city with polycentric CBD. Conclusions are drawn suggestion are given for policy making for the sustainability of Muscat City.

Keywords: land-use transportation, transportation modeling urban form, urban structure, urban rule parameters

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Authors: Amdouni Hamida, Gammoudi Mohamed Mohsen

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In order to help the expert to validate association rules extracted from data, some quality measures are proposed in the literature. We distinguish two categories: objective and subjective measures. The first one depends on a fixed threshold and on data quality from which the rules are extracted. The second one consists on providing to the expert some tools in the objective to explore and visualize rules during the evaluation step. However, the number of extracted rules to validate remains high. Thus, the manually mining rules task is very hard. To solve this problem, we propose, in this paper, a semi-automatic method to assist the expert during the association rule's validation. Our method uses rule-based classification as follow: (i) We transform association rules into classification rules (classifiers), (ii) We use the generated classifiers for data classification. (iii) We visualize association rules with their quality classification to give an idea to the expert and to assist him during validation process.

Keywords: association rules, rule-based classification, classification quality, validation

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Authors: Mahsa Shafaei Bajestani, Mahmoud Yazdani, Aliakbar Golshani

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Artificial lightweight aggregates have a wide range of applications in industry and engineering. Nowadays, the usage of this material in geotechnical activities, especially as backfill in retaining walls has been growing due to the specific characteristics which make it a competent alternative to the conventional geotechnical materials. In practice, a material with lower weight but higher shear strength parameters would be ideal as backfill behind retaining walls because of the important roles that these parameters play in decreasing the overall active lateral earth pressure. In this study, two types of Light Expanded Clay Aggregates (LECA) produced in the Leca factory are investigated. LECA is made in a rotary kiln by heating natural clay at different temperatures up to 1200 °C making quasi-spherical aggregates with different sizes ranged from 0 to 25 mm. The loose bulk density of these aggregates is between 300 and 700 kN/m³. The purpose of this research is to determine the stress-strain behavior, shear strength parameters, and the energy absorption of LECA materials. Direct shear tests were conducted at five normal stresses of 25, 50, 75, 100, and 200 kPa. In addition, conventional triaxial compression tests were operated at confining pressures of 50, 100, and 200 kPa to examine stress-strain behavior. The experimental results show a high internal angle of friction and even a considerable amount of nominal cohesion despite the granular structure of LECA. These desirable properties along with the intrinsic low density of these aggregates make LECA as a very proper material in geotechnical applications. Furthermore, the results demonstrate that lightweight aggregates may have high energy absorption that is excellent alternative material in seismic isolations.

Keywords: expanded clay, direct shear test, triaxial test, shear properties, energy absorption

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Authors: Mansouri Ouarda, Adbdennour Cherif, Boukarma Ziad

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Environmental and biological monitoring are used for the evaluation of exposure to industrial chemicals, and provide a tool for assessing workers’ exposure to chemicals. The organs or tissues where the first biological effects can be observed with increasing amounts of lead toxicity. This study aims at evaluating the effect of the metal element-trace; lead, on the sex hormones in male workers, exposed to this metal on the level of the manufacturing plant of lead accumulators. The results indicate a significant reduction of the testosterone concentration in exposed workers compared to the control. However, the rate of LH was strongly increased at the individuals exposed to Pb. A significant difference concerning the rate of FSH, the hormone Prolactin and cortisol was recorded. The indicators of the lead poisoning indicate a very highly significant increase in the value of Pbs which vary between (142-796 µg/L) among which 50% of the workers present a high lead poisoning and the value of PPZ which vary between (43-554µg/L). The biochemical parameters show a significant increase in the rate of the créatinine, the urea and the acid urique. The hepatic results show no significant differentiation in the rate of TGO and TGP between both groups of study. However the rates of the enzyme phosphatase alkaline, triglyceride, and cholesterol a significant difference were registered.

Keywords: hormons, parameters, physilogical, Pbs, PPZ

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Authors: Amitkumar Barot, Vijaykumar Sinha

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There is growing interest in the development of new materials based on recycled polymers from plastic waste, and also in the field of lubricants much effort has been spent on substitution of petro-based raw materials by natural-based renewable ones. This is due to the facts of depleting fossil fuels and due to strict environmental laws. In relevance to this, new technique for the formulation of grease that combines the chemical recycling of poly (ethylene terephthalate) PET with the use of castor oil (CO) has been developed. Comparison to diols used in chemical recycling of PET, castor oil is renewable, easily available, environmentally friendly, economically cheaper and hence sustainability indeed. The process parameters like CO concentration and temperature were altered, and further, the influences of the process parameters have been studied in order to establish technically and commercially viable process. Further thereby formed depolymerized product find an application as base oil in the formulation of grease. A depolymerized product has been characterized by various chemical and instrumental methods, while formulated greases have been evaluated for its tribological properties. The grease formulated using this new environmentally friendly approach presents applicative properties similar, and in some cases superior, compared to those of a commercial grease obtained from non-renewable resources.

Keywords: castor oil, grease formulation, recycling, sustainability

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Authors: Francisco Espinosa, Juan Chavarría

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Glycerol is a byproduct of biodiesel production that can be used for aqueous-phase reforming to obtain hydrogen. Iridium is a material that has high activity and hydrogen selectivity for steam phase reforming. Nevertheless, a drawback for the use of iridium in aqueous-phase reforming is the low activity in water-gas shift reaction. Therefore, in this work, it is proposed the use of nickel and copper as a second metal in the catalyst to reach a synergetic effect. Iridium, iridium-nickel and iridium-copper catalysts were prepared by incipient wetness impregnation and evaluated in the aqueous-phase reforming of glycerol using CeO₂ or La₂O₃ as support. The catalysts were characterized by XRD, XPS, and EDX. The reactions were carried out in a fixed bed reactor feeding a solution of glycerol 10 wt% in water at 270°C, and reaction products were analyzed by gas chromatography. It was found that IrNi/CeO₂ reached highest glycerol conversion and hydrogen production, slightly above 70% and 43 vol% respectively. In terms of conversion, iridium is a promising metal, and its activity for hydrogen production can be enhanced when adding a second metal.

Keywords: aqueous-phase reforming, glycerol, hydrogen production, iridium

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Authors: Jinan B. Al-Dabbagh, Rozman Mohd Tahar, Mahadzir Ishak

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TiAl alloy nano-powder was successfully produced by a mechanical alloying (MA) technique in a planetary ball mill. The influence of milling parameters, such as the milling duration, rotation speed, and balls-to-powder mass ratio, on the characteristics of the Ti50%Al powder, including the microstructure, crystallite size refinement, and phase formation, were investigated. It was found that MA of elemental Ti and Al powders promotes the formation of TiAl alloys, as Ti (Al) solid solution was formed after 5h of milling. Milling without the addition of process control agents led to a dramatic decrease in the crystallite size to 17.8 nm after 2h of milling. Higher rotation energy and a higher ball-to-powder weight ratio also accelerated the reduction in crystallite size. Subsequent heating up to 850°C resulted in the formation of a new intermetallic phase with a dominant TiAl3 phase plus minor γ-TiAl or α2-Ti3Al phase or both. A longer milling duration also exhibited a better effect on the micro-hardness of Ti50%Al powders.

Keywords: TiAl alloys, nanocrystalline materials, mechanical alloying, materials science

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Authors: Akshay Paranjape, Nils Plettenberg, Robert Schmitt

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Producing faulty products can be costly for manufacturing companies and wastes resources. To reduce scrap rates in manufacturing, process parameters can be optimized using machine learning. Thus far, research mainly focused on optimizing specific processes using traditional algorithms. To develop a framework that enables real-time optimization based on a predictive model for an arbitrary production process, this study explores the application of reinforcement learning (RL) in this field. Based on a thorough review of literature about RL and process parameter optimization, a model based on maximum a posteriori policy optimization that can handle both numerical and categorical parameters is proposed. A case study compares the model to state–of–the–art traditional algorithms and shows that RL can find optima of similar quality while requiring significantly less time. These results are confirmed in a large-scale validation study on data sets from both production and other fields. Finally, multiple ways to improve the model are discussed.

Keywords: reinforcement learning, production process optimization, evolutionary algorithms, policy optimization, actor critic approach

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Authors: Nitin Singh, Meng Ling, Talha Ahmed, Tianxia Zhao, Reinier van de Pol

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We propose the use of reinforcement learning (RL) as a viable alternative for optimizing supply chain management, particularly in scenarios with stochasticity in product demands. RL’s adaptability to changing conditions and its demonstrated success in diverse fields of sequential decision-making makes it a promising candidate for addressing supply chain problems. We investigate the impact of demand fluctuations in a multi-product supply chain system and develop RL agents with learned generalizable policies. We provide experimentation details for training RL agents and statistical analysis of the results. We study the generalization ability of RL agents for different demand uncertainty scenarios and observe superior performance compared to the agents trained with fixed demand curves. The proposed methodology has the potential to lead to cost reduction and increased profit for companies dealing with frequent inventory movement between supply and demand nodes.

Keywords: inventory management, reinforcement learning, supply chain optimization, uncertainty

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Authors: Atabak Rahimzadeh Ilkhch

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Friction stir processing (FSP) has promised for application of thermo-mechanical processing techniques where aims to change the micro structural and mechanical properties of materials in order to obtain high performance and reducing the production time and cost. There are lots of studies focused on the microstructure of friction stir welded aluminum alloys. The main focus of this research is on the grain size obtained in the weld zone. Moreover in second part focused on temperature distribution effect over the entire weld zone and its effects on the microstructure. Also, there is a need to have more efforts on investigating to obtain the optimal value of effective parameters such as rotational speed on microstructure and to use the optimum tool designing method. the final results of this study will be present the variation of structural and mechanical properties of materials in the base of applying Friction stir processing and effect of (FSP) processing and tensile testing on surface quality. in the hand, this research addresses the FSP f AA-7020 aluminum and variation f ration of rotation and translational speeds.

Keywords: friction stir processing, AA-7020, thermo-mechanical, microstructure, temperature

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Authors: Bilge Yaman Islak, Erhan Ayas

Abstract:

The densification behavior of TiB₂ – Ti₃SiC₂ composites is investigated for temperatures in the range of 1200°C to 1400°C, for the pressure of 40 and 50MPa, and for holding time between 15-30 min by spark plasma sintering (SPS) technique. Ti, Si, TiC and 5 wt.% TiB₂ were used to synthesize TiB₂ – Ti₃SiC₂ composites and the effect of different sintering parameters on the densification and phase evolution of these composites were investigated. The bulk densities were determined by using the Archimedes method. The polished and fractured surfaces of the samples were examined using a scanning electron microscope equipped with an energy dispersive spectroscopy (EDS). The phase analyses were accomplished by using the X-Ray diffractometer. Sintering temperature and holding time are found to play a dominant role in the phase development of composites. TiₓCᵧ and TiSi₂ secondary phases were found in 5 wt.%TiB₂ – Ti₃SiC₂ composites densified at 1200°C and 1400°C under the pressure of 40 MPa, due to decomposition of Ti₃SiC₂. The results indicated that 5 wt.%TiB₂ – Ti₃SiC₂ composites were densified into the dense parts with a relative density of 98.77% by sintering at 1300 °C, for 15 min, under a pressure of 50 MPa via SPS without the formation of any other ancillary phase. This work was funded and supported by Scientific Research Projects Commission of Eskisehir Osmangazi University with the Project Number 201915C103 (2019-2517).

Keywords: densification, phase evolution, sintering, TiB₂ – Ti₃SiC₂ composites

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Authors: Benallou Yassine, Amara Kadda, Bouazza Boubakar, Soudini Belabbes, Arbouche Omar, M. Zemouli

Abstract:

The study of the pressure effect on the materials, their functionality and their properties is very important, insofar as it provides the opportunity to identify others applications such the optical properties in the alkaline earth chalcogenides, as like the SrS. Here we present the first-principles calculations which have been performed using the full potential linearized augmented plane wave method (FP-LAPW) within the Generalized Gradient Approximation developed by Perdew–Burke–Ernzerhor for solids (PBEsol). The calculated structural parameters like the lattice parameters, the bulk modulus B and their pressure derivative B' are in reasonable agreement with the available experimental and theoretical data. In addition, the elastic properties such as elastic constants (C11, C12, and C44), the shear modulus G, the Young modulus E, the Poisson’s ratio ν and the B/G ratio are also given. The treatments of exchange and correlation effects were done by the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential for the electronic. The pressure effect on the electronic properties was visualized by calculating the variations of the gap as a function of pressure. The obtained results are compared to available experimental data and to other theoretical calculations

Keywords: SrS, GGA-PBEsol+TB-MBJ, density functional, Perdew–Burke–Ernzerhor, FP-LAPW, pressure effect

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Authors: Fabiola M. Villalobos-Castaldi, Nicolás C. Kemper, Esther Rojas-Krugger, Laura G. Ramírez-Sánchez

Abstract:

This paper presents the classification results about exploring the combination of a motion based approach with a local appearance method to describe the facial motion caused by the muscle contractions and expansions that are presented in facial expressions. The proposed feature extraction method take advantage of the knowledge related to which parts of the face reflects the highest deformations, so we selected 4 specific facial regions at which the appearance descriptor were applied. The most common used approaches for feature extraction are the holistic and the local strategies. In this work we present the results of using a local appearance approach estimating the correlation coefficient to the 4 corresponding landmark-localized facial templates of the expression face related to the neutral face. The results let us to probe how the proposed motion estimation scheme based on the local appearance correlation computation can simply and intuitively measure the motion parameters for some of the most relevant facial regions and how these parameters can be used to recognize facial expressions automatically.

Keywords: facial expression recognition system, feature extraction, local-appearance method, motion-based approach

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Authors: Gurpreet Singh, Hazoor Singh, Kulbir Singh Sandhu

Abstract:

Friction Stir Welding Process emerged as promising solid-state welding and eliminates various welding defects like cracks and porosity in joining of dissimilar aluminum alloys. In the present research, Friction Stir Welding (FSW) is carried out on dissimilar aluminum alloys 2000 series and 6000 series this combination of alloys are highly used in automobile and aerospace industry due to their good strength to weight ratio, mechanical, and corrosion properties. The joints characterized by applying various destructive and non-destructive tests. Three critical welding parameters were considered i.e. Tool Rotation speed, Transverse speed, and Tool Geometry. The effective range of tool rotation speed from 1200-1800 rpm and transverse speed from 60-240 mm/min and tool geometry was studied. The two-different difficult to weld alloys were successfully welded. All the samples showed different microstructure with different set of welding parameters. It has been revealed with microstructure scans that grain refinement plays a crucial role in mechanical properties.

Keywords: aluminum alloys, friction stir welding, mechanical properties, microstructure

Procedia PDF Downloads 281