Search results for: steady state rolling

Authors: Huazhen Lin, Ruihua Xu, Zhibin Jiang

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In this real-world case, timetabling the LRT network as a whole is rather challenging for the operator: they are supposed to create a timetable to avoid various route conflicts manually while satisfying a given interval and the number of rolling stocks, but the outcome is not satisfying. Therefore, the operator adopts a computerised timetabling tool, the Train Plan Maker (TPM), to cope with this problem. However, with various constraints in the dual-line network, it is still difficult to find an adequate pairing of turnback time, interval and rolling stocks’ number, which requires extra manual intervention. Aiming at current problems, a one-off model for timetabling is presented in this paper to simplify the procedure of timetabling. Before the timetabling procedure starts, this paper presents how the dual-line system with a ring and several branches is turned into a simpler structure. Then, a non-linear programming model is presented in two stages. In the first stage, the model sets a series of constraints aiming to calculate a proper timing for coordinating two lines by adjusting the turnback time at termini. Then, based on the result of the first stage, the model introduces a series of inequality constraints to avoid various route conflicts. With this model, an analysis is conducted to reveal the relation between the ratio of trains in different directions and the possible minimum interval, observing that the more imbalance the ratio is, the less possible to provide frequent service under such strict constraints.

Keywords: light rail transit (LRT), non-linear programming, railway timetabling, timetable coordination

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Authors: Kirti Gosavi, Anita Bhole

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The paper demonstrates simulation and steady-state performance of three phase squirrel cage induction motor and detection of rotor broken bar fault using MATLAB. This simulation model is successfully used in the fault detection of rotor broken bar for the induction machines. A dynamic model using PWM inverter and mathematical modelling of the motor is developed. The dynamic simulation of the small power induction motor is one of the key steps in the validation of the design process of the motor drive system and it is needed for eliminating advertent design errors and the resulting error in the prototype construction and testing. The simulation model will be helpful in detecting the faults in three phase induction motor using Motor current signature analysis.

Keywords: squirrel cage induction motor, pulse width modulation (PWM), fault diagnosis, induction motor

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Authors: Galit Truman Zinman

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The 'Islamic State' (IS) is one of the most successful jihadist groups in the modern history. The 'Islamic State' strives to realize the idea of erasing the borders between Muslim countries and establishing a wide Islamic caliphate. The 'Islamic State' is based on religious unity and opposition to existing political order. In this paper, the main argument is that the 'Islamic State' is characterized by two significant tendencies of state-building: preservation and change. The methodology of this study is based on the process tracing method and the analysis of primary sources: decisions, announcements and speeches of religious leaders of the Islamic State, slogans, rituals and symbols, audio and video clips produced by the Al-Hayat Media Center, films distributed on YouTube, as well as the content analysis of Dabiq`s articles (IS official Journal) and nasheeds (jihadi songs). The major findings of this study indicate that in practice the 'Islamic State' uses the same socio-political functions typical to the modern state (preservation), but introduces a different religious-ideological content (change). On the one hand, there is a preservation of the principles of existing modern state. Even with the rejection of secularization, globalization, and nationalism, there is an establishment of typical modern nation-state patterns. It is still a state entity, which has an ideological infrastructure, territory, population, governance and a monopoly on the use of violence, security services, justice system, tax collection, etc. All these functions characterize the modern state, and despite the desire of the 'Islamic State' to create a new kind of state, it reminds patterns of the typical modern nation-state. As for the religious-ideological content of the new state, here we can see a tendency of great change. The 'Islamic State' aims to create an Islamic caliphate which would allow the establishment of religious law and order, under a big commitment to return civilization to a seventh-century environment. The 'Islamic State' favors the fight against Western culture and its liberal ideology. It supports the struggle for global jihad against the unbelievers. Today, despite the territorial 'contraction' and the undermining of the organization's governance in Iraq and Syria, the 'Islamic State' continues to maintain its brand among jihadist activists around the world.

Keywords: Islamic State, Islamic caliphate, modern nation-state, religious law and order

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Authors: Pramod Somvanshi, Manu Tomar, K. V. Venkatesh

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Insulin and glucagon are responsible for homeostasis of key plasma metabolites like glucose, amino acids and fatty acids in the blood plasma. These hormones act antagonistically to each other during the secretion and signaling stages. In the present work, we analyze the effect of macronutrients on the response from integrated insulin and glucagon signaling pathways. The insulin and glucagon pathways are connected by DAG (a calcium signaling component which is part of the glucagon signaling module) which activates PKC and inhibits IRS (insulin signaling component) constituting a crosstalk. AKT (insulin signaling component) inhibits cAMP (glucagon signaling component) through PDE3 forming the other crosstalk between the two signaling pathways. Physiological level of anabolism and catabolism is captured through a metric quantified by the activity levels of AKT and PKA in their phosphorylated states, which represent the insulin and glucagon signaling endpoints, respectively. Under resting and starving conditions, the phosphorylation metric represents homeostasis indicating a balance between the anabolic and catabolic activities in the tissues. The steady state analysis of the integrated network demonstrates the presence of a bistable response in the phosphorylation metric with respect to input plasma glucose levels. This indicates that two steady state conditions (one in the homeostatic zone and other in the anabolic zone) are possible for a given glucose concentration depending on the ON or OFF path. When glucose levels rise above normal, during post-meal conditions, the bistability is observed in the anabolic space denoting the dominance of the glycogenesis in liver. For glucose concentrations lower than the physiological levels, while exercising, metabolic response lies in the catabolic space denoting the prevalence of glycogenolysis in liver. The non-linear positive feedback of AKT on IRS in insulin signaling module of the network is the main cause of the bistable response. The span of bistability in the phosphorylation metric increases as plasma fatty acid and amino acid levels rise and eventually the response turns monostable and catabolic representing diabetic conditions. In the case of high fat or protein diet, fatty acids and amino acids have an inhibitory effect on the insulin signaling pathway by increasing the serine phosphorylation of IRS protein via the activation of PKC and S6K, respectively. Similar analysis was also performed with respect to input amino acid and fatty acid levels. This emergent property of bistability in the integrated network helps us understand why it becomes extremely difficult to treat obesity and diabetes when blood glucose level rises beyond a certain value.

Keywords: bistability, diabetes, feedback and crosstalk, obesity

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Authors: Ali Reza Tahavvor, Saeed Hosseini, Nazli Jowkar, Behnam Amiri

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Heat transfer of leaves is a crucial factor in optimal operation of metabolic functions in plants. In order to quantify this phenomenon in different leaves and investigate the influence of leaf shape on heat transfer, natural convection for pine, orange and olive leaves was simulated as representatives of different groups of leaf shapes. CFD techniques were used in this simulation with the purpose to calculate heat transfer of leaves in similar environmental conditions. The problem was simulated for steady state and three-dimensional conditions. From obtained results, it was concluded that heat fluxes of all three different leaves are almost identical, however, total rate of heat transfer have highest and lowest values for orange leaves and pine leaves, respectively.

Keywords: computational fluid dynamic, heat flux, heat transfer, natural convection

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Authors: Monika Florczak-Wator

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The model of positive obligations of the state concerning the protection of the rights of an individual was created within the jurisdiction of the German Federal Constitutional Court in the 1970s. That model assumes that the state should protect an individual against infringement of their fundamental rights by another individual. It is based on the idea concerning the modification of the function and duties of the state towards an individual and society. Initially the state was perceived as the main infringer of the fundamental rights of an individual formulating the individual’s obligations of negative nature (obligation of noninterference), however, at present the state is perceived as a guarantor and protector of the fundamental rights of an individual of positive nature (obligation of protection). Examination of the chosen judicial decisions of that court will enable us to determine what the obligation of protection is specifically about, when it is updated and whether it is accompanied by claims of an individual requesting the state to take actions protecting their fundamental rights against infringement by the private entities. The comparative perspective for the German model of positive obligations of the state will be an analogous model present in the jurisdiction of the European Court of Human Rights. It is justified to include it in the research as the Convention, similarly to the constitution, focuses on the protection of an individual against the infringement of their rights by the state and both models have been developed within the jurisdiction for several dozens of years. Analysis of the provisions of the Constitution of the Republic of Poland as well as judgements of the Polish Constitutional Tribunal will allow for the presentation of the application the model of the protective duties of the state in Poland.

Keywords: human rights, horizontal relationships, constitution, state protection

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Authors: M. Hadji, A. Haddad, Y. Hadji

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The effects of boronizing treatment on the friction coefficient and wear behavior of Ti2AlC were investigated. In order to modify the surface properties of Ti2AlC, boronizing treatment was carried out through powder pack cementation in the 1150-1350 °C temperature range. After boronizing treatment, one mixture layer, composed of TiB2 and SiC, forms on the surface of Ti2AlC. The growth of the coating is processed by inward diffusion of Boron and obeys a linear rule. The Boronizing treatment increases the hardness of Ti2AlC from 6 GPa to 13GPa. In the pin-on-disc test, it was found that the material undergoes a steady-state coefficient of friction of around 0.8 and 0.45 in case of Ti2AlC/Al2O3 tribocouple under 7N load for the non treated and the boronized samples, respectively. The wear resistance of Ti2AlC under Al2O3 ball sliding has been significantly improved, which indicated that the boronizing treatment is a promising surface modification way of Ti2AlC.

Keywords: MAX phase, wear, hardness, boronizing

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Authors: H. Aminfar, M. Mohammadpourfard, K. Khajeh

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This paper has focused on the most important parameters in the LSC uptake; inlet Re number and Sc number in the presence of non-uniform magnetic field. The magnetic field is arising from the thin wire with electric current placed vertically to the arterial blood vessel. According to the results of this study, applying magnetic field can be a treatment for atherosclerosis by reducing LSC along the vessel wall. Homogeneous porous layer as a arterial wall has been regarded. Blood flow has been considered laminar and incompressible containing Ferro fluid (blood and 4 % vol. Fe₃O₄) under steady state conditions. Numerical solution of governing equations was obtained by using the single-phase model and control volume technique for flow field.

Keywords: LDL surface concentration (LSC), magnetic field, computational fluid dynamics, porous wall

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Authors: Mohood A. Bamidele, Fadairo O. Olokesunsi, Muhammed A. Yunus

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This research work focuses on tourism and poverty alleviation in Osun State, it delves in the tourism resources of the state and strategic framework that has been put in place to manage the cultural base tourism that is most prominent in the state. The major instrument used for data collection was questionnaire which was designed for the area and data collected were analyzed using statistical table and chi-square analysis. The result revealed that tourism is under development in Osun State and the tourism potential of the state is yet to be exploited, this is due to lack of appropriate policy to master the development and management of tourism resources, poor publicity, awareness, and lack of adequate basic infrastructure. The research work, therefore, recommended, that, there should be proper and appropriate policy, and that the government should take a leading step to develop tourism in Osun State by creating a workable environment to the private sector and given a substantial budgetary allocation to the tourism in the state.

Keywords: appropriate policy, poor publicity, poverty alleviation, substantial budgetary allocation

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Authors: Anjali Uday, Yuting Wang, Andres Alfonso Pena Olare

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The Discrete Element Method is a promising approach to modeling microscopic behaviors of granular materials. The quality of the simulations however depends on the model parameters utilized. The present study focuses on calibration and validation of the discrete element parameters for Cuxhaven sand based on the experimental data from triaxial and oedometer tests. A sensitivity analysis was conducted during the sample preparation stage and the shear stage of the triaxial tests. The influence of parameters like rolling resistance, inter-particle friction coefficient, confining pressure and effective modulus were investigated on the void ratio of the sample generated. During the shear stage, the effect of parameters like inter-particle friction coefficient, effective modulus, rolling resistance friction coefficient and normal-to-shear stiffness ratio are examined. The calibration of the parameters is carried out such that the simulations reproduce the macro mechanical characteristics like dilation angle, peak stress, and stiffness. The above-mentioned calibrated parameters are then validated by simulating an oedometer test on the sand. The oedometer test results are in good agreement with experiments, which proves the suitability of the calibrated parameters. In the next step, the calibrated and validated model parameters are applied to forecast the micromechanical behavior including the evolution of contact force chains, buckling of columns of particles, observation of non-coaxiality, and sample inhomogeneity during a simple shear test. The evolution of contact force chains vividly shows the distribution, and alignment of strong contact forces. The changes in coordination number are in good agreement with the volumetric strain exhibited during the simple shear test. The vertical inhomogeneity of void ratios is documented throughout the shearing phase, which shows looser structures in the top and bottom layers. Buckling of columns is not observed due to the small rolling resistance coefficient adopted for simulations. The non-coaxiality of principal stress and strain rate is also well captured. Thus the micromechanical behaviors are well described using the calibrated and validated material parameters.

Keywords: discrete element model, parameter calibration, triaxial test, oedometer test, simple shear test

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Authors: Talal S. Abdullah, Shahin Mehraban, Geraint Lodwig, Nicholas P. Lavery

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The defining property of Interstitial Free (IF) steels is formability, comprehensively measured using the Lankford coefficient (r-value) on uniaxial tensile test data. The contributing factors supporting this feature are grain size, orientation, and elemental additions. The processes that effectively modulate these factors are the casting procedure, hot rolling, and heat treatment. An existing methodology is well-practised in the steel Industry; however, large-scale production and experimentation consume significant proportions of time, money, and material. Introducing small-scale rapid alloy prototyping (RAP) as an alternative process would considerably reduce the drawbacks relative to standard practices. The aim is to finetune the existing fundamental procedures implemented in the industrial plant to adapt to the RAP route. IF material is remelted in the 80-gram coil induction melting (CIM) glovebox. To birth small grains, maximum deformation must be induced onto the cast material during the hot rolling process. The rolled strip must then satisfy the polycrystalline behaviour of the bulk material by displaying a resemblance in microstructure, hardness, and formability to that of the literature and actual plant steel. A successful outcome of this work is that small-scale RAP can achieve target compositions with similar microstructures and statistically consistent mechanical properties which complements and accelerates the development of novel steel grades.

Keywords: rapid alloy prototyping, plastic anisotropy, interstitial free, miniaturised tensile testing, formability

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Authors: Julian David Rios Acuna

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This paper seeks to argue that the phenomenon of ‘paramilitarism’ in Colombia exhibits the role of violence as constitutive of the political process of state formation in the country. In order to do this, it takes as its point of departure a landmark moment in the long history of private armies known as the ‘paramilitary’ in Colombia. In 2001, paramilitary commanders, politicians, and members of the military and other branches of state power singed what is known as the ‘Pact of Ralito.’ In this pact, the paramilitary appropriated constitutional and legal language. The paper argues that this appropriation shows that the paramilitary and the state express the same claim to sovereign power and therefore have the same foundation. More precisely, paramilitary power shows itself to base its power on the same foundation as the legal order, namely, extreme forms of violence where death is generative of power. In this sense, the paper shows how, by sharing its foundation, Colombian paramilitarism exhibits that state power in Colombia can be characterized as necro-power as Achille Mbembe understands it. The paper argues that paramilitarism shows state power as necro-power by constituting itself as a symptom understood, following Zizek, as that which both shows and overthrows its own foundation. In this way, paramilitarism shows the foundation of the state, thereby reconfiguring this very state. This reconfiguration, explicitly based on necro-power, the paper concludes, transforms the state into a form more appropriate to the political demands of neo-liberalism. By exhibiting its foundation in necro-power through paramilitarism, the Colombian State turns from a liberal into a (neo)liberal democracy.

Keywords: necro-power, necropolitics, paramilitarism in Colombia, state formation, state power, sovereign power

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Authors: Beghdadi Lotfi, Bouziane Abdelhafid

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A finite volume method for quadrilaterals unstructured mesh is developed to predict the two dimensional steady-state solutions of conduction equation. In this scheme, based on the integration around the polygonal control volume, the derivatives of conduction equation must be converted into closed line integrals using same formulation of the Stokes theorem. To valid the accuracy of the method two numerical experiments s are used: conduction in a regular block (with known analytical solution) and conduction in a rotated block (case with curved boundaries).The numerical results show good agreement with analytical results. To demonstrate the accuracy of the method, the absolute and root-mean square errors versus the grid size are examined quantitatively.

Keywords: Stokes theorem, unstructured grid, heat transfer, complex geometry

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Authors: Liudmila Shabalinskaya, Victor Golovanov, Liudmila Milinis, Sergey Loponos, Alexander Maslov, D. O. Frolov

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The work is devoted to the rapid laboratory diagnosis of the condition of aircraft friction units, based on the application of the nondestructive testing method by analyzing the parameters of wear particles, or tribodiagnostics. The most important task of tribodiagnostics is to develop recommendations for the selection of more advanced designs, materials and lubricants based on data on wear processes for increasing the life and ensuring the safety of the operation of machines and mechanisms. The object of tribodiagnostics in this work are the tooth gears of the central drive and the gearboxes of the gas turbine engine of the civil aviation PS-90A type, in which rolling friction and sliding friction with slip occur. The main criterion for evaluating the technical state of lubricated friction units of a gas turbine engine is the intensity and rate of wear of the friction surfaces of the friction unit parts. When the engine is running, oil samples are taken and the state of the friction surfaces is evaluated according to the parameters of the wear particles contained in the oil sample, which carry important and detailed information about the wear processes in the engine transmission units. The parameters carrying this information include the concentration of wear particles and metals in the oil, the dispersion composition, the shape, the size ratio and the number of particles, the state of their surfaces, the presence in the oil of various mechanical impurities of non-metallic origin. Such a morphological analysis of wear particles has been introduced into the order of monitoring the status and diagnostics of various aircraft engines, including a gas turbine engine, since the type of wear characteristic of the central drive and the drive box is surface fatigue wear and the beginning of its development, accompanied by the formation of microcracks, leads to the formation of spherical, up to 10 μm in size, and in the aftermath of flocculent particles measuring 20-200 μm in size. Tribodiagnostics using the morphological analysis of wear particles includes the following techniques: ferrography, filtering, and computer analysis of the classification and counting of wear particles. Based on the analysis of several series of oil samples taken from the drive box of the engine during their operating time, a study was carried out of the processes of wear kinetics. Based on the results of the study and comparing the series of criteria for tribodiagnostics, wear state ratings and statistics of the results of morphological analysis, norms for the normal operating regime were developed. The study allowed to develop levels of wear state for friction surfaces of gearing and a 10-point rating system for estimating the likelihood of the occurrence of an increased wear mode and, accordingly, prevention of engine failures in flight.

Keywords: aviation, box of drives, morphological analysis, tribodiagnostics, tribology, ferrography, filtering, wear particle

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Authors: Muhamad Sani Buang, Shahrul Azam Abdullah, Juri Saedon

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There is not much effective guideline on development of design parameters selection on springback for advanced high strength steel sheet metal in U-channel process during cold forming process. This paper presents the development of predictive model for springback in U-channel process on advanced high strength steel sheet employing Response Surface Methodology (RSM). The experimental was performed on dual phase steel sheet, DP590 in U-channel forming process while design of experiment (DoE) approach was used to investigates the effects of four factors namely blank holder force (BHF), clearance (C) and punch travel (Tp) and rolling direction (R) were used as input parameters using two level values by applying Full Factorial design (24). From a statistical analysis of variant (ANOVA), result showed that blank holder force (BHF), clearance (C) and punch travel (Tp) displayed significant effect on springback of flange angle (β2) and wall opening angle (β1), while rolling direction (R) factor is insignificant. The significant parameters are optimized in order to reduce the springback behavior using Central Composite Design (CCD) in RSM and the optimum parameters were determined. A regression model for springback was developed. The effect of individual parameters and their response was also evaluated. The results obtained from optimum model are in agreement with the experimental values

Keywords: advance high strength steel, u-channel process, springback, design of experiment, optimization, response surface methodology (rsm)

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Authors: Aritras Roy, Rinku Mukherjee

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The current study couples a quasi-steady Vortex Lattice Method and a camber correcting technique, ‘Decambering’ for unsteady post-stall flow prediction. The wake is force-free and discrete such that the wake lattices move with the free-stream once shed from the wing. It is observed that the time-averaged unsteady coefficient of lift sees a relative drop at post-stall angles of attack in comparison to its steady counterpart for some angles of attack. Multiple solutions occur at post-stall and three different algorithms to choose solutions in these regimes show both unsteadiness and non-convergence of the iterations. The distribution of coefficient of lift on the wing span also shows sawtooth. Distribution of vorticity changes both along span and in the direction of the free-stream as the wake develops over time with distinct roll-up, which increases with time.

Keywords: post-stall, unsteady, wing, aerodynamics

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Authors: Rebecca Rumbul

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The operation of the state can often appear opaque to citizens wishing to access official information, who have to negotiate a path through numerous levels of bureaucracy rationalized through institutional policy to acquire what information they want. Even where individual states have 'Right to Information' legislation guaranteeing citizen access to information, public sector conformity to such laws vary between states and between state organizations. In response to such difficulties in bringing citizens and information together, many NGO's around the world have begun designing and hosting digital portals to facilitate the requesting and receiving of official information. How then, are these 'civic technology' tools affecting the behavior of the state? Are they increasing the transparency of the state? This study looked at 5 Right to Information civic technology sites in Chile, Uruguay, Ukraine, Hungary and the UK, and found that such sites were providing a useful platform to publish official information, but that states were still reluctant to comply with all requests. It concludes that civic technology can be an important tool in increasing the transparency of the state, but that the state must have an institutional commitment to information rights for this to be fully effective.

Keywords: digital, ICT, transparency, civic technology

Procedia PDF Downloads 635

Authors: T. Poppendieker

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A new innovative tool for self-myofascial release is widely and increasingly used among athletes of various sports. The application of the foam roll is suggested to improve muscle performance and flexibility. Attempts to examine acute and somewhat long term effects of either have been conducted over the past ten years. However, the results of muscle performance have been inconsistent. It is suggested that regular use over a long period of time results in a different, muscle performance improving outcome. This study examines long-term effects of regular foam rolling combined with a short plyometric routine vs. solely the same plyometric routine on muscle performance and flexibility over a period of six weeks. Results of counter movement jump (CMJ), squat jump (SJ), and isometric maximal force (IMF) of a 90° horizontal squat in a leg-press will serve as parameters for muscle performance. Data on the range of motion (ROM) of the sit and reach test will be used as a parameter for the flexibility assessment. Muscle activation will be measured throughout all tests. Twenty male and twenty female members of a Frankfurt area fitness center chain (7.11) with an average age of 25 years will be recruited. Women and men will be randomly assigned to a foam roll (FR) and a control group. All participants will practice their assigned routine three times a week over the period of six weeks. Tests on CMJ, SJ, IMF, and ROM will be taken before and after the intervention period. The statistic software program SPSS 22 will be used to analyze the data of CMJ, SJ, IMF, and ROM under consideration of muscle activation by a 2 x 2 x 2 (time of measurement x gender x group) analysis of variance with repeated measures and dependent t-test analysis of pre- and post-test. The alpha level for statistic significance will be set at p ≤ 0.05. It is hypothesized that a significant difference in outcome based on gender differences in all four tests will be observed. It is further hypothesized that both groups may show significant improvements in their performance in the CMJ and SJ after the six-week period. However, the FR group is hypothesized to achieve a higher improvement in the two jump tests. Moreover, the FR group may increase IMF as well as flexibility, whereas the control group may not show likewise progress. The results of this study are crucial for the understanding of long-term effects of regular foam roll application. The collected information on the matter may help to motivate the incorporation of foam rolling into training routines, in order to improve athletic performances.

Keywords: counter movement jump, foam rolling, isometric maximal force, long term effects, self-myofascial release, squat jump

Procedia PDF Downloads 270

Authors: M. Hadji, A. Haddad, Y. Hadji

Abstract:

The effects of boronizing treatment on the friction coefficient and wear behavior of 0.35 Vf TiC- Ti3 SiC2 composite were investigated. In order to modify the surface properties of Ti3SiC2, boronizing treatment was carried out through powder pack cementation in the 1150-1350 °C temperature range. After boronizing treatment, one mixture layer, composed of TiB2 and SiC, forms on the surface of Ti3SiC2. The growth of the coating is processed by inward diffusion of Boron and obeys a linear rule. The Boronizing treatment increases the hardness of Ti3SiC2 from 6 GPa to 13 GPa. In the pin-on-disc test, i twas found that the material undergoes a steady-state coefficient of friction of around 0.8 and 0.45 in case of Ti3SiC2/Al2O3 tribocouple under 7 N load for the non treated and the boronized samples, respectively. The wear resistance of Ti3SiC2 under Al2O3 ball sliding has been significantly improved, which indicated that the boronizing treatment is a promising surface modification way of Ti3SiC2.

Keywords: MAX phase, boronizing, hardness, wear

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Authors: I. Muslih, A. Alkhalailah, A. Merdji

Abstract:

Photovoltaic efficiency is highly affected by dust accumulation; the dust particles prevent direct solar radiation from reaching the panel surface; therefore a reduction in output power will occur. A study of dust and soiling accumulation effect on the output power of PV panels was conducted for different periods of time from May to October in three countries of the MENA region, Jordan, Egypt, and Algeria, under local weather conditions. This study leads to build a more realistic equation to estimate the power reduction as a function of time. This logarithmic function shows the high reduction in power in the first days with 10% reduction in output power compared to the reference system, where it reaches a steady state value after 60 days to reach a maximum value of 30%.

Keywords: dust effect, MENA, solar energy, PV system

Procedia PDF Downloads 189

Authors: M. Hadji, A. Haddad, Y. Hadji

Abstract:

The effects of boronizing treatment on the friction coefficient and wear behavior of 0.35 Vf TiC- Ti3 SiC2 composite were investigated. In order to modity the surface properties of Ti3SiC2, boronizing treatment was carried out through powder pack cementation in the 1150-1350 °C temperature range. After boronizing treatment, one mixture layer, composed of TiB2 and SiC, forms on the surface of Ti3SiC2. The growth of the coating is processed by inward diffusion of Boron and obeys a linear rule. The Boronizing treatment increases the hardness of Ti3SiC2 from 6 GPa to 13 GPa. In the pin-on-disc test, i twas found that the material undergoes a steady-state coefficient of friction of around 0.8 and 0.45 in case of Ti3SiC2/Al2O3 tribocouple under 7N load for the non treated and the boronized samples, respectively. The wear resistance of Ti3SiC2 underAl2O3 ball sliding has been significantly improved, which indicated that the boronizing treatment is a promising surface modification way of Ti3SiC2.

Keywords: MAX phase, wearing, friction, boronizing

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Authors: Malika Imoula, Rachid Saci, Renee Gatignol

Abstract:

A numerical investigation is carried out to analyze vortex flows in a free surface cylinder, driven by the independent rotation and differentially heated boundaries. As a basic uncontrolled isothermal flow, we consider configurations which exhibit steady axisymmetric toroidal type vortices which occur at the free surface; under given rates of the bottom disk uniform rotation and for selected aspect ratios of the enclosure. In the isothermal case, we show that sidewall differential rotation constitutes an effective kinematic means of flow control: the reverse flow regions may be suppressed under very weak co-rotation rates, while an enhancement of the vortex patterns is remarked under weak counter-rotation. However, in this latter case, high rates of counter-rotation reduce considerably the strength of the meridian flow and cause its confinement to a narrow layer on the bottom disk, while the remaining bulk flow is diffusion dominated and controlled by the sidewall rotation. The main control parameters in this case are the rotational Reynolds number, the cavity aspect ratio and the rotation rate ratio defined. Then, the study proceeded to consider the sensitivity of the vortex pattern, within the Boussinesq approximation, to a small temperature gradient set between the ambient fluid and an axial thin rod mounted on the cavity axis. Two additional parameters are introduced; namely, the Richardson number Ri and the Marangoni number Ma (or the thermocapillary Reynolds number). Results revealed that reducing the rod length induces the formation of on-axis bubbles instead of toroidal structures. Besides, the stagnation characteristics are significantly altered under the combined effects of buoyant-thermocapillary convection. Buoyancy, induced under sufficiently high Ri, was shown to predominate over the thermocapillay motion; causing the enhancement (suppression) of breakdown when the rod is warmer (cooler) than the ambient fluid. However, over small ranges of Ri, the sensitivity of the flow to surface tension gradients was clearly evidenced and results showed its full control over the occurrence and location of breakdown. In particular, detailed timewise evolution of the flow indicated that weak thermocapillary motion was sufficient to prevent the formation of toroidal patterns. These latter detach from the surface and undergo considerable size reduction while moving towards the bulk flow before vanishing. Further calculations revealed that the pattern reappears with increasing time as steady bubble type on the rod. However, in the absence of the central rod and also in the case of small rod length l, the flow evolved into steady state without any breakdown.

Keywords: buoyancy, cylinder, surface tension, toroidal vortex

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Authors: M. Akif Ceviz, Alirıza Kaleli, Erdoğan Güner

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LPG pressure regulator is a device which is used to change the phase of LPG from liquid to gas by decreasing the pressure. During the phase change, it is necessary to supply the latent heat of LPG to prevent excessive low temperature. Engine coolant is circulated in the pressure regulator for this purpose. Therefore, pressure regulator is a type of heat exchanger that should be designed for different engine operating conditions. The design of the regulator should ensure that the flow of LPG is in gaseous phase to the injectors during the engine steady state and transient operating conditions. The pressure regulators in the LPG gaseous injection systems currently used can easily change the phase of LPG, however, there is no any control on the LPG temperature in conventional LPG injection systems. It is possible to increase temperature excessively. In this study, a control unit has been tested to keep the LPG temperature in a band. Result of the study showed that the engine performance characteristics can be increased by using the system.

Keywords: temperature, pressure regulator, LPG, PID

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Authors: Yuri A. Gruber, Matheus Rosendo, Ulisses G. A. Casemiro, Klaus de Geus, Rafael T. Bee

Abstract:

Lightning strikes can cause severe negative impacts to the electrical sector causing direct damage to equipment as well as shutdowns, especially when occurring in power substations. In order to mitigate this problem, a meticulous planning of the power substation protection system is of vital importance. A critical part of this is the distribution of shielding wires through the substation, which creates a 3D imaginary protection mesh similar to a circus tarpaulin. Equipment enclosed in the volume defined by that 3D mesh is considered protected against lightning strikes. The use of traditional methods of longitudinal cutting analysis based on 2D CAD tools makes the process laborious and the results obtained may not guarantee satisfactory protection of electrical equipment. This work describes the application of a Game Engine to the problem of lightning protection of power substations providing the visualization of the 3D protection mesh, the amount of protected components and the highlight of equipment which remain unprotected. In addition, aspects regarding the implementation and the advantages of approaching the problem using Unreal® Engine 4 are described. In order to validate results, a comparison with traditional 2D methods is applied to the same case study to which the proposed technique has been applied. Finally, a comparative study involving different levels of protection using the technique developed in this work is presented, showing that modern game engines can be a powerful accessory for simulations in several areas of engineering.

Keywords: game engine, rolling spheres method, substation protection, UE4, Unreal Engine 4

Procedia PDF Downloads 507

Authors: E. K. Linsenmayer

Abstract:

Traditional international relations theorists define state security, the principal national interest, as a state’s military force. However, many political theorists argue the current definition of security is not comprehensive and therefore, problematic. This paper argues that women’s physical security is not only linked but also necessary to achieve state security. In today’s unipolar political international system, the United States continues to accredit national security to its military. However, in one of the most militarized countries, women remain insecure. Through a case study method of the United States, this paper illuminates a necessary political prescription: the empowerment of women through an inside-out, feminist theoretical approach that makes state security attainable. The research through empirical testing, drawing from several databases, shows the positive effects of women’s physical security on state security. Women’s physical security is defined in terms of equal legal practices, health, education, and female representation in the government. State security is measured by the relative peace of a state, its involvement in conflict and a state’s relations with neighboring states. This paper shows that empowering women, 50% of the world’s population, is necessary for ending the current vicious circle of militarization, war, and insecurity. Without undoing gender power dynamics at the individual and societal level, security at all levels remains unattainable.

Keywords: gender inequality, politics, state security, women's security

Procedia PDF Downloads 183

Authors: Boubaker Fezzani, Ridha Ben Cheikh, Tarek Rouissi

Abstract:

In this work the original ADM1, implemented in the simulation software package MATLAB/Simulink, was modified and adapted and applied to reproduce the experimental results of the mesophilic anaerobic digestion of Esperto paper industry wastewater in a batch digester. The data set from lab-scale experiment runs were used to calibrate and validate the model. The simulations’ results indicated that the modified ADM1 was able to predict reasonably well the steady state results of gas flows, methane and carbon dioxide contents, pH and total volatile fatty acids (TVFA) observed with all influents concentrations.

Keywords: anaerobic digestion, mathematical modelling, Simulation, ADM1, batch digester, esparto paper industry effluent, mesophilic temperature

Procedia PDF Downloads 376

Authors: Akbar Jamali

Abstract:

Hegel is the first great political philosopher who specifically contemplates on bureaucracy. For Hegel bureaucracy is the function of the state. Since state, essentially is a rational organization, its function; namely, bureaucracy must be rational. Since, what is rational is universal; Hegel had to explain how the bureaucracy could be understood as universal. Hegel discusses bureaucracy in his treatment of ‘executive power’. He analyses modern bureaucracy as a form of political organization, its constituent members, and its relation to the social environment. Therefore, the essence of bureaucracy in Hegel’s philosophy is the implementation of law and rules. Hegel argues that unlike the other social classes that are particular because they look for their own private interest, bureaucracy as a class is a ‘universal’ because their orientation is the interest of the state. State for Hegel is essentially rational and universal. It is the actualization of ‘objective Spirit’. Marx criticizes Hegel’s argument on the universality of state and bureaucracy. For Marx state is equal to bureaucracy, it constitutes a social class that based on the interest of bourgeois class that dominates the society and exploits proletarian class. Therefore, the main disagreement between these political philosophers is: whether the state (bureaucracy) is universal or particular. Growing e-government in modern state as an important aspect of development leads us to contemplate on the particularity and universality of e-government. In this article, we will argue that e-government essentially is universal. E-government, in itself, is impartial; therefore, it cannot be particular. The development of e-government eliminates many side effects of the private, personal or particular interest of the individuals who work as bureaucracy. Finally, we will argue that more a state is developed more it is universal. Therefore, development of e-government makes the state a more universal and affects the modern philosophical debate on the particularity or universality of bureaucracy and state.

Keywords: particularity, universality, rational bureaucracy, impartiality

Procedia PDF Downloads 218

Authors: Eleni Ioannou, Pascal Nucara, Keith Pullen

Abstract:

The subject of this paper is the investigation of the best efficiency design of a compressor diffuser applied in new lightweight, ultra efficient micro-gas turbine engines for vehicles. The Computational Fluid Dynamics (CFD) results are obtained utilizing steady state simulations for a wedge and an ”oval” type pipe diffuser in an effort to identify the beneficial effects of the pipe diffuser design. The basic flow features are presented with particular focus on the optimization of the pipe diffuser leading to higher efficiencies for the compressor stage. The optimised pipe diffuser is designed to exploit the 3D freedom enabled by Selective Laser Melting, hence purposely involves an investigation of geometric characteristics that do not follow the traditional diffuser concept.

Keywords: CFD, centrifugal compressor, micro-gas turbine, pipe diffuser, SLM, wedge diffuser

Procedia PDF Downloads 376

Authors: Wheyming Song, Hung-Hsiang Lin, Scott Lian

Abstract:

In this research, we investigate the optimal dispatching rule for machines and manpower allocation in the solar ingot-wafer systems. The performance of the method is measured by the sales profit for each dollar paid to the operators in a one week at steady-state. The decision variables are identification-number of machines and operators when each job is required to be served in each process. We propose a rule which is a function of operator’s ability, corresponding salary, and standing location while in the factory. The rule is named ‘Multi-nominal distribution dispatch rule’. The proposed rule performs better than many traditional rules including generic algorithm and particle swarm optimization. Simulation results show that the proposed Multi-nominal distribution dispatch rule improvement on the sales profit dramatically.

Keywords: dispatching, solar ingot, simulation, flexsim

Procedia PDF Downloads 275

Authors: Z. Zerdoumi, D. Benatia, , D. Chicouche

Abstract:

This paper investigates the application of artificial neural network to the problem of nonlinear channel equalization. The difficulties caused by channel distortions such as inter symbol interference (ISI) and nonlinearity can overcome by nonlinear equalizers employing neural networks. It has been shown that multilayer perceptron based equalizer outperform significantly linear equalizers. We present a multilayer perceptron based equalizer with decision feedback (MLP-DFE) trained with the back propagation algorithm. The capacity of the MLP-DFE to deal with nonlinear channels is evaluated. From simulation results it can be noted that the MLP based DFE improves significantly the restored signal quality, the steady state mean square error (MSE), and minimum Bit Error Rate (BER), when comparing with its conventional counterpart.

Keywords: Artificial Neural Network, signal restoration, Nonlinear Channel equalization, equalization

Procedia PDF Downloads 475