Paper by M. Ajay Kumar, N. V. Srikanth, et al. “An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions” in Volume 4, Issue 1, 27–38/March 2014 doi: 10.2478/s13531-013-0143-4 contains an error in the title. The correct title is presented below
This paper examines the effect of MHD, and injection through one side of a long vertical channel embedded in porous medium with transpiration cooling. The governing nonlinear partial differential equations have been transformed by similarity transformation into a set of ordinary differential equations, which are solved numerically by Adam-moultan Predictor-Corrector method with Newton-Raphson Method for missing initial conditions. Proflles of dimensionless velocity, temperature and concentration are shown graphically for different parameters entering into the analysis. Also the effects of the pertinent parameters on the heat transfer rates are tabulated. An analysis of the results obtained shows that the flow field is influenced appreciably by emerging parameters of the present study.
In this paper, a comparative study of dipole and patch antennas commonly used in portable telephones is investigated. The two models antennas are considered working at 900, 1800 and 2450 MHz bands. Thus, we have included different distances between the mobile phone and the human head model. This study shows the effects of electromagnetic waves on the human head model. The objective is to evaluate the SAR in simulation anatomic based model of the human head for different antenna-head distances and in many frequencies. All numerical simulations results are performed using Ansoft HFSS software.
Today’s automobile manufacturers are increasingly using lightweight materials to reduce weight; these include plastics, composites, aluminium, magnesium alloys, and also new types of high strength steels. Many of these materials have limited strength or ductility, therefore in many cases the rupture being serious consequences during crashes, underscore Picketta et al. in their studies. Automotive structures must deform plastically in a short period of time, a few milliseconds, to absorb the crash energy in a controllable manner. It must be light and enable economically mass-production [1]. FE models rapidly gained acceptance among engineers. Many other factors facilitated the development of vehicle models by shell finite elements since most of the geometry of the structural surfaces was already on computer graphic files. Kee Poong Kim and Hoon Huh emphasize that the crashworthiness of each vehicle part needs to be evaluated at the initial stage of design for good performance of an assembled vehicle. As the dynamic behaviour of structural members is different from the static one, the crashworthiness of the vehicle structures has to be assessed by impact analysis. The paper analyzes the influence of trigger geometry upon the compression of thin-walled cylindrical tubes. Simulations performed on a simple model showed the dependence between triggers area and deformation times as well as the maximum deformations obtained for various speeds at which the simulations ware carried out. Likewise, the geometry of trigger leads to different results.
Compiler is a tool to translate abstract code containing natural language terms to machine code. Meta compilers are available to compile more than one languages. We have developed a meta framework intends to combine two dissimilar programming languages, namely C++ and Java to provide a flexible object oriented programming platform for the user. Suitable constructs from both the languages have been combined, thereby forming a new and stronger Meta-Language. The framework is developed using the compiler writing tools, Flex and Yacc to design the front end of the compiler. The lexer and parser have been developed to accommodate the complete keyword set and syntax set of both the languages. Two intermediate representations have been used in between the translation of the source program to machine code. Abstract Syntax Tree has been used as a high level intermediate representation that preserves the hierarchical properties of the source program. A new machine-independent stack-based byte-code has also been devised to act as a low level intermediate representation. The byte-code is essentially organised into an output class file that can be used to produce an interpreted output. The results especially in the spheres of providing C++ concepts in Java have given an insight regarding the potential strong features of the resultant meta-language.
Middle East, like North Africa, is considered as arid to semi-arid region. Water shortages in this region, represents an extremely important factor in stability of the region and an integral element in its economic development and prosperity. Iraq was an exception due to presence of Tigris and Euphrates Rivers. After the 1970s the situation began to deteriorate due to continuous decrease in discharges of these rivers, are expected to dry by 2040 with the current climate change. In the present paper, long rainfall trends up to the year 2099 were studied in Sinjar area, northwest of Iraq, to give an idea about its future prospects. Two emission scenarios, used by the Intergovernmental Panel on Climate Change (A2 and B2), were employed to study the long term rainfall trends in northwestern Iraq. All seasons consistently project a drop in daily rainfall for all future periods with the summer season is expected to have more reduction compared to other seasons. Generally the average rainfall trend shows a continuous decrease. The overall average annual rainfall is slightly above 210 mm. In view of these results, prudent water management strategies have to be adopted to overcome or mitigate consequences of future severe water crisis.
An approach for estimating critical buckling strain of pipe subjected plastic bending is established in the present paper. A rigid — perfectly plastic material model and cross section ovalization of pipe during bending are employed for the approach. The energy rates of the ovalised pipe bending and the cross section ovalising are proposed firstly. Furthermore, these energy rates are combined to perform the buckling analysis of pipe bending, an estimation formula of critical buckling strain for pipe subjected plastic bending is proposed. The predicting result of the new critical buckling strain formula is compared with the available experimental data, it shows that the formula is valid.
The performance and reliability of grounding grids depend on its structural integrity. If grounding conductors are damaged, it may cause misoperation of protective relay which leads to trip feeders unnecessarily. It can also cause not only failures on the surroundings such as the grounding grid, secondary circuits’ cables, and structural elements but also voltage hazard for human. The circuits may attain unacceptable voltages when short-circuit fault currents occur in these grids. This paper presents the development of a new technique to monitor the operating conditions of the grounding grids of high voltage apparatus and systems without any diggings and forced outages. New concept, principals, a technique and a device shown in the paper have never been described before by the other authors. The technique is based on the evaluation of the electromagnetic field distribution pattern over the damaged horizontal elements of the grid.
In this paper, G′/G-expansion and tanh-methods, as two well known methods, for solving partial differential equations are compared. It has been shown that these two methods are the same, for solving partial Differential equation in special conditions. For illustration and more explanation of the idea, two examples are provided.
Paper by Paul Bere, Calin Neamtu. “Methodology for evaluate the form deviations for formula one nose car” in Volume 4, Issue 2, 148–154/June 2014 doi: 10.2478/s13531-013-0158-x contains an error in the author’s affiliation and descriptions of figures. The correct affiliation and descriptions of figures are presented below.
The paper presents the basis for the design of thermal-hydraulic generators running in a single regime. The thermal-hydraulic generators in a single regime running represent an absolute novelty worldwide (a pioneer invention). Based on the methodology concerning this subject, the design calculus for an experimental model was developed.
Activated carbon derived from pine cones waste was prepared by carbonization at 450°C, activated by different activating agents: ZnCl 2 , H 2 SO 4 and NaOH, and then pyrolyzed at 600°C. Adsorption of Cr VI and other heavy metals (Mn II, Fe II, Cu II) on activated carbons was investigated to evaluate the adsorption properties. Special attention was paid to the effects of carbon surface functionalities that were analyzed by FT-IR and zeta potential study. Moreover, XRD study of activated carbon was also carried out. Results had shown that activated carbon by NaOH was the best adsorbent for removal of chromium VI from wastewater. The solid-solution interaction was determined by analyzing the adsorption isotherms at room temperature at different pH. When pH is above 4, the removal fraction of Cr (VI) ions decreased with the increase of pH. The removal fraction of Cr (VI) ions decreased below pH 4. The preferable removal of Cu (II) over Mn(II) and Fe (II) could be due to its lower affinity to solvent.Pseudo-second order equation provided the better correlation for the adsorption kinetics data. Equilibrium isotherms were determined by Fowler-Guggenheim model.
Our paper realizes a study of the equilibrium positions for an engine supported by four identical nonlinear springs of quadratic characteristic. The systems with quadratic characteristic are generally avoided because they lead to mathematical complications. Our goal is to realize such a study for an engine supported on quadratic springs. For the model purposed, we established the equations of motion and we discussed the possibilities for the equilibrium positions. Because of the quadratic characteristic of the springs and of the approximations made for the small rotations, the equations obtained for the equilibrium lead us to a paradox, which consists in the existence of an open neighborhood in which there exists an infinity of positions of indifferent equilibrium, or a curve where the equilibrium positions are situated. Moreover, the study of the stability shows that the stability is assured for the position at which the springs are not compressed. Finally, a numerical example is presented and completely solved.
In the present work, Ni-P-PTFE-Al 2 O 3 nanodispersion coatings were developed on mild steel. These coatings were heat treated and were exposed to 3.5% NaCl solution. Thus obtained as plated, heat treated and exposed coatings were investigated for their corrosion and wear behavior together with other tribological properties. SEM/EDAX and X-ray diffractometry were used to analyze composition and structural changes of the coatings. Corrosion parameters of the coated samples were obtained from electrochemical polarization and immersion tests. Microhardness, wear resistance and friction coefficient of the coatings were also measured. The results showed that heat treatment at 200°C has little effect on the coating whereas treatment at 400°C results in enhanced crystallinity due to formation of intermetallics phases and possibly aluminum phosphide. Beyond this temperature at 600°C coarsening of the grains occurs which reduces the number of hardening sites. These structural changes result in the observance of highest hardness and lowest wear rate in case of coatings treated at 400°C. Corrosion resistance of the coated samples was observed to decrease with the heat treatment presumably due to the various physical and structural changes of the coating components. Similar changes were observed on their exposure to the corrosive media.
The present research is concerned with predicting liquefaction potential and pore water pressure under the dynamic loading on fully saturated sandy soil using the finite element method by QUAKE/W computer program. As a case study, machine foundations on fully saturated sandy soil in different cases of soil densification (loose, medium and dense sand) are analyzed. Harmonic loading is used in a parametric study to investigate the effect of several parameters including: the amplitude frequency of the dynamic load. The equivalent linear elastic model is adopted to model the soil behaviour and eight node isoparametric elements are used to model the soil. Emphasis was made on zones at which liquefaction takes place, the pore water pressure and vertical displacements develop during liquefaction. The results showed that liquefaction and deformation develop fast with the increase of loading amplitude and frequency. Liquefaction zones increase with the increase of load frequency and amplitude. Tracing the propagation of liquefaction zones, one can notice that, liquefaction occurs first near the loading end and then develops faraway. The soil overburden pressure affects the soil liquefaction resistance at large depths. The liquefaction resistance and time for initial liquefaction increase with increasing depths. When the frequency changes from 5 to 10 rad/sec. (approximately from static to dynamic), the response in displacement and pore water pressure is very pronounced. This can be attributed to inertia effects. Further increase of frequency leads to smaller effect on displacement and pore water pressure. When the frequency is low; 5, 10 and 25 rad/sec., the oscillation of the displacement ends within the period of load application 60 sec., while when ω = 50 rad/sec., oscillation continues after this period.
Our work consists in the development and setting of an electronic information panel designed to monitor road traffic informational characteristics (velocity, vehicle length and flow density). This information is available using two displays installed above the monitored traffic line. Wishing a “just in time” warning for the driver, the display of the instantaneous speed was represented by the green light if it falls within the legal speed and red light if it is over the legal speed. Our aim was to develop an informing, monitoring and data storing equipment, able to record the time, the speed and the length of crossing vehicles. A test version, which consists of three main modules: the detection module, a programmable controller and an information panel, was designed and a complex hardware and software equipment was manufactured. The efficiency, reliability and stability in operation were the chosen criteria for the detection module. The programmable controller processes the data collected from detectors and displays it. In the future, the hardware platform will allow the connection to other devices (eg. GPRS modem), aiming to achieve the possibility to operate independently or integrated into a system of remote macro-monitoring (idea for further development).
We apply the variational iteration method (VIM) for solving linear and nonlinear ordinary differential equations with variable coefficients. We use distinct Lagrange multiplier for each order of ODE. We emphasize the power of the method by testing a variety of models with distinct orders and variable coefficients. Scientific models, namely, the hybrid selection model, the Thomas-Fermi equation, the Kidder equation of the Unsteady flow of gas through a porous medium, and the Riccati equation, are studied as well.
The paper elaborates a mathematical model in order to conduct a study into the dynamics of tractor-trailer systems during braking. The braking dynamics is analyzed by considering two versions for the braking system: 1) braking applied on the rear axle and 2) braking applied on all four wheels. In both versions the trailer is braked on all wheels. The mathematical model enables us to determine and graphically illustrate the evolution of the following parameters: braking deceleration, braking speed and the distance traveled by the tractor during braking. The mathematical model elaborated is applied on a tractor-trailer system completing transportation works.
Optimization of activities with the aim to provide quality service in conditions of high profitability, is one of the main objectives chased by managers in transportation companies. As a consequence, directing the attention towards monitoring of maintenance activities of vehicles fleet, can achieve desired results. Two of the most important issues related to the maintenance activity, is the increase of reliability and reduction of fuel consumption of the vehicles fleet. Aforementioned actions represents a way forward for raising the quality and profitability of services offered. In this paper, the main ways of monitoring the fuel consumption, in order to reduce it and increase the reliability of transportation vehicles fleet, are presented. For the evaluation of the maintenance system and the degree of influence of malfunctions recorded on the fuel consumption, using the Pareto -ABC method, following case study on a fleet of buses for urban public transport has been conducted. Results obtained highlights the deficiencies of the maintenance process carried out and constitutes a solid base for the reorganization of the maintenance activity, involving preventive maintenance activities, in order to contribute decisively to the results targeted by the management of transport companies.
The radiation characteristics of a stacked microstrip antenna geometry proficient of providing circular polarization along with wide impedance bandwidth is simulated by using IE3D software and later on this antenna was fabricated on FR-4 substrate with an air gap and testing is done in free space. The feed location, location of applied shorting pin and width of air gap introduced between driver element and parasitically coupled element were optimized to obtain best results. The measured impedance bandwidth better than 31.72% and axial ratio bandwidth close to 1.68% were achieved with the proposed geometry. The simulated and measured results obtained are in good match with each other.
