Published Articles Archive

Abstract
One kind of steering systems in vehicles is Steering by Wire (SBW). Control and stability of this method are important issues. In fact the SBW system is very suitable for Four Wheel Steering systems. In this paper the SBW used for Four Wheel Steering system to take result. The effect of 4ws on turning is shown. When a 4ws system turns at low speed, the rear Wheels steer in the opposite direction as the front wheels, so that the maneuverability and parking of the system increases. At higher speed the rear wheels steer in the same direction as the front wheels, so that more stability and less lateral rear force are resulted. In this paper, a bicycle model is used for dynamic modeling for testing the stability and controllability. This model is built with the assumption theorem. Steer by wire is used for steering the rear and front wheels. The lateral rear force is estimated with a Hall Effect sensor.

Abstract
The raising sustainability awareness of consumers has brought the discourse about environmental impacts of products into pulic discourse. Industry has had to respond to this demand for sustainable products. Among the different customers groups, teenagers play a considerable role: Sustainability is particularly important for the younger generations. Children and teenagers of today are going to have to cope with the consequences of negligence of previous and current generations in protecting the environmental and social situation. It is thus important to understand how children and teenagers perceive the problem, and how they will act as consumers in the future. This paper discusses a project where teenagers were surveyed to find out about the importance of sustainability and quality aspects of products. Electronic entertainment products and clothing products were considered as it is assumed that teenagers mostly spend their pocket money for these two branches of products.

Abstract
In this research landslide, hazard zonation provided based on fuzzy logic method and investigating of this model is efficiency. In the first provided the geology of slope and aspect maps by using aerial photos topography maps and field operations in watershed management of Karaj. Then, these maps classes of priority and coming next determine based on
existing landslides area in the geology, slope and aspect of maps in GIS software. In the geology map of Karaj formation (contain shale, tuff, marl, sandstone and conglomerate) and Tizkuh formation (contain limestone) and in the slope map of percent 25≤ S< 45 and 0≤ S

Abstract
The simplest solution to Einstein's field equations is the Schwarzschild solution. This solution is not able to describe any nonspherical shaped objects. Some stars and galaxies are ellipsoidal. Consequently, the gravitational field around these objects should be different in comparison with the spherical form. This paper is considering a new line element so that we are able to construct not only spherical objects but also we are able to explain an ellipsoidal object too. This new line element is more accurate and complete than the Schwarzschild line element. In this research, we see that the Schwarzschild line element and its solution is only a part of the whole work, which we have done. For more consideration, we applied this metric to an arbitrary object in the next step. Moreover, we used this line element for the solution of a planetary orbit of an ellipsoid planet by using Einstein’s field equations. These equations used for the exterior solution of an ellipsoidal celestial object.

Abstract
In this paper, we have used the general nonlinear Schrödinger equation (GNLSE) to study the spectral evolution of a short light pulse propagating through an optical fiber. The equation includes the main factors affecting its propagation through the fiber, involving the linear and nonlinear dispersive characteristics. We find the asymmetry feature of the spectrum due to the Raman Effect. The first order group velocity dispersion sets in after a finite propagation length. We have systematically studied the evolution of the pulse through a nonlinear medium.

Abstract
Corrosion can be protected by the application of protective coatings developed by organic resins. Metal lose due to corrosion affects a country economic to a higher extent. Organic coating is the cheapest method to prevent corrosion. Silicone and polyester resins have good physical, mechanical and anticorrosive properties. They can be blended and made hybrid networks. Various concentrations of the two resins were mixed. The curing agent used in the study was polyisocyanate. The network of different functional groups between silicone and polyester resins was examined by FTIR spectroscopy. The crosslink formation between the resins was observed by the identification and analysis of NH bond, Si-O-Si, Si-O-C functional groups.The developed coating systems have got adhesion property which was evaluated by cross hatch test. Electrochemical Impedance Spectroscopy (EIS) was used to study the anticorrosion property of the systems by exposing the samples to 3% NaCl solution. EIS experimental results show that the coatings could protect the metal surface for the exposure to corrosive medium for more than 30 days.

Abstract
A simple, highly sensitive, accurate and selective method for determination of trace amounts of Pb(II) in water samples is presented. The method is based on selective chelation of Pb(II) on surfactant coated alumina, modified with a Schiff’s base (Z)-Furan-2-carbaldehyde Thiosemicarbazone (I). The retained ions were then eluted with 4 ml of 4 M nitric acid and determined by flame atomic absorption spectrometry(FAAS) at 283.3 for Pb. The influence of flow rates of sample and eluent solutions, pH, breakthrough volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant coated alumina adsorbs 40 mg of the Schiff’s base which in turn can retain 15.0±0.9mg of each of the two ions. The limit of detection (3σ) for Pb(II) was found to be 5.57 ng l -1. The enrichment factor for both ions is 100. The mentioned method was successfully applied on determination of lead in different water samples. The ions were also speciated by means of three columns system.

Abstract
In this work, layered of silicon suboxide/gold/silicon suboxide (SiOx/Au/SiOx) films were prepared by using hot-wire plasma enhanced chemical vapor deposition (HW-PECVD) system. The films prepared underwent rapid thermal annealing (RTA) process for time periods of 100s, 500s and 700s at temperature of 800oC in vacuum. The effects of RTA on the structural and morphology from FE-SEM, Auger and XRD measurement of the films were studied. The surface plasmon resonance (SPR) effect exhibited by Au particles was obtained from the optical absorption spectra. SPR peaks were exhibited by films which annealed for long time duration. The band gap energy of the annealed samples was found to be in the range of 1.8 to 2.05 eV.

Abstract
Today, technological developments increase very fast and plenty of hi-tech products are seen in the global market. With the influence of consumerism, these products are sold frequently and their life cycles become shorter. Hence, they have already begun to accumulate at the garbage dumps. Many of these products, such as electronic and electrical equipment (EEE) have a significant negative impact on the environment and human health and cause resource depletion. Ecodesign is used as a set of proactive strategies that aims to reduce the total environmental impact of a product at the design stage and leads to sustainability. There are many methods and tools for ecodesign. Although they are widespread, they can not cover all design phases and there are still shortcomings in the tools for engineering designers as to accomplish ecodesign. To understand the requirements of designers in order to succeed in the ecodesign process, design experts from academia and experts from EEE producing companies have been surveyed. The results of the surveys can help to set up general requirements for the development of a holistic ecodesign tool.

Abstract
In this report, nanowires of Zn2SiO4 and SnO2 have been successfully synthesized using a simple novel method namely thermal ramping technique. The technique applies thermal ramping of the sample to a temperature of 900 oC using carbothermal reduction method. This technique requires no carrier gas. Elemental analysis and crystal structure were evaluated using Field Emission Scanning Electron Microscopy (FESEM) , Energy Dispersive X-ray (EDX) and X-ray Diffraction(XRD) analysis. Nanowires of SnO2 and Zn2SiO4 with diameter ranging from 15-25 nm were observed. The effect of Au thickness in synthesizing Zn2SiO4 is also discussed.

Abstract
The effects of buffer gas pressure, electrical input power and pulse repetition frequency on the output power of 510.6- and 578.2nm transitions have been experimentally investigated in a copper vapor laser with small-bore tube (11mm of diameter and 580mm of length). It is observed that the output power characteristics are strongly influenced by these parameters. A maximum output power of laser is obtained at about 4W with 27 kHz of pulse repetition frequency, 30 torr of Ne buffer gas pressure and 1.42kW of electrical input power. The waveforms of the current, tube voltage and laser pulses have also been observed.

Abstract
FePt nanoparticles attract great research interest for possible application to ultrahigh density magnetic recording media. In this paper, FePt magnetic nanoparticles were synthesized by superhydride reduction of FeCl2 and Pt(acac)2 at high temperature. Adding superhydride (LiBEt3H) to the phenyl ether solution of FeCl2 and Pt(acac)2 in the presence of oleic acid, oleylamine, and 1,2-hexadecanediol at 200 °C, followed by refluxing at 250 °C, led to monodisperse 3 nm FePt nanoparticles. The effect of reflux process on the size and uniformity of FePt nanoparticles has been investigated. TEM images showed that the size of FePt nanoparticles increase to 4 nm with reflux process and the standard deviation of FePt nanoparticles increase to 10 % which lead to improve the uniformity of FePt nanoparticles. The results of EDS analysis showed that the Fe shell around FePt nanoparticles increase with increasing reflux time and the composition of FePt nanoparticles gives Fe68Pt32 after 10 min reflux.

Abstract
T Meteor is a luminous effect, light is created as the rocky body is frictionally heated to incandescence when entering Earth's atmosphere. The ionized trails of the meteor are also capable of reflecting radio signals from terrestrial stations, which include those broadcasted by commercial FM and TV stations. For this research, 3 sites are identified as candidates but only the best will ultimately be utilized to do the research. The selection criterion depends on the radio frequency interference (RFI) level and whether they have any free FM frequency from local radio stations. The 3 sites are Jelebu in Negeri Sembilan, Behrang in Perak and Merang in Terengganu. The best site is Behrang and the average floor noise level at this site within the FM frequencies of 88 MHz to 108 MHz is -97.111 dBm. The average number of meteor detections in the span of three days is 48 meteors per day. A number of 50 underdense and 38 overdense meteor trails are detected for the first day.

Abstract
In this Paper, the nonlinear free and force vibration of a single-walled carbon nanotube (SWCNT) with simply supported ends is investigated based on von Karman’s geometric nonlinearity. The SWCNT described as an individual shell and the Donnell’s equations of cylindrical shells are used to obtain the governing equations. The Galerkin's procedure is used to discretized partial differential equations of the governing into the ordinary differential equations of motion. The method of averaging is applied to analyze the nonlinear vibration of (10, 0), (20, 0) and (30, 0) zigzag SWCNTs in the analytical calculations. The effects of the nonlinear parameters, different aspect ratios, different circumferential wave numbers and longitudinal half-wave numbers are investigated. Both free and forced motions (due to harmonic excitation) are considered. It is shown that (30, 0) zigzag SWCNT has less nonlinear behavior than the other CNTs for a constant aspect ratio. The type of nonlinearity is determined by the aspect ratio. It is seen from the results that for Small values of aspect ratios, the vibration behavior is softening type for the low amplitudes, and it is hardening type for the large amplitudes. And for large value of the aspect ratio, the vibration behavior is hardening type for all amplitudes.

Abstract
Organic coatings play an important role in preventing the metal substrate from the adverse effects of corrosion. Coatings are developed by single polymeric resins and or a combination of resins with or without pigments Silicone resin (S2) and polyester resin (P2) was used to develop binders with different weight ratios. Polyisocyanate was used as the curing agent. Physical, mechanical, thermal, and electrical properties were studied. The maximum value 5B has been attained by the S240P260 and S250P250 coatings. The binders containing 40% S2 and 70% P2 and 50% S2 and 50% P2 showed high performance compared to the samples containing 20, 30, 70 and 80% of S2 40% P2 resin with S2 resins withstood temperatures up to 448 K for 24 hours and from the potential time measurement it has been found that S240P260 could withstand without any formation of corrosion for a longer time.

Abstract
We measured full energy peak efficiency of High-Purity Germanium detector which is important for gamma-ray spectrometry experiments. A brief but very effective description on the basic formation of detector crystal and creation of signal pulse has been presented here. This article is furnished in such a way that the contents find useful and interesting to physics and electronics students, educators, and also researchers who are generally reading outside their specialties to broaden their understanding of physics and to expand and enhance their pedagogical toolkits at the undergraduate and graduate levels.

Abstract
The dynamical tensoproperties of simples Si , Si , Si and Si at temperatures Т=293К and Т=273К are investigated. The strongly increasing of dynamical tensosensitivity these specified simples at speed of change of pressure P\t >108 Pa/s in comparison with their statistical tensosensitivities is shown.

Abstract
X-ray powder diffraction data for a new Cadmium Zinc Tellurium compound synthesized by Bridgman technique is reported. The unit cell dimensions were determined from diffractometer methods using CuK radiation, and the indexing programs. The cubic phase was the sole crystalline phase which detected by X-ray diffraction analysis in the Cd0.29Zn0.71Te sample with lattice constants of a= 6.26218(34) Å, The results are in agreement with those obtained from cadmium Zinc tellurium (Cd0.4Zn0.6Te) PDF carte number (50-1438).

Abstract
Considering effects of tidal plus centrifugal stress acting on icy-rocks and the tensile strength thereof, icy-rocks being in the density range (1–2.4) g cm-3 which had come into existence as collisional ejecta (debris) in the vicinity of Pluto at the time when Pluto-Charon system came into being as a result of a giant impact of a Kuiper Belt Object on the primordial Pluto, it is shown, here, that these rocks going around Pluto in its vicinity are under slow disruption generating a stable ring structure consisting of icy-rocks of diameters in the range (20–90) km, together with fine dust and particles disrupted off the rocks, and spread all over the regions in their respective Roche Zones, various Roche radii being in ~1/2 three-body mean motion resonance. Calculations of gravitational spheres of influence of Pluto which turns out to be 4.2 x 106 km for prograde orbits and 8.5 x 106 km for retrograde orbits together with the existence of Kuiper Belt in the vicinity of Pluto assure that there may exist a few rocks (satellites)/dust rings/sheets so far undiscovered moving in prograde orbits around the planet and few others which are distant ones and move around Pluto in the region between 4.2x106 km and 8.5x106 km in retrograde orbits.

Abstract
Polypyrrole-poly(vinyl alcohol) (PPy-PVA) conducting polymer composite films were prepared on Indium Tin Oxide (ITO) glass electrode from an aqueous solution containing pyrrole monomer, p-toluenesulfonate electrolyte and poly(vinyl alcohol) insulating polymer by electrochemical method. The prepared composite films were characterized by conductivity and electromagnetic interference (EMI) shielding measurements, dynamic mechanical analysis (DMA) and optical microscopy. The conductivity data of PPy-PVA shows that with the increase in PVA concentration in aqueous pyrrole solution used to prepare the films, the conductivity of the prepared PPy-PVA composite films increased upto a certain level and later it showed a decreasing trend with further increase in PVA concentration used to prepare the composite films. The dynamic mechanical analysis (DMA) shows the evidence of the enhanced mechanical properties of PPy-PVA composite film over PPy film. The optical micrographs show the changes of morphology of the prepared composite films with the PVA concentration. The results of electromagnetic interference (EMI) shielding effectiveness measured in the microwave range of 8-12 GHz show that a shielding effectiveness of 45.67 dB was exhibited by PPy-PVA composite films.