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The present study investigates experimentally heat transfer of the forced convection boiling of a R134a/nano oil mixture in a horizontally-aligned tube with an aluminum helical fin. The effects of various parameters including refrigerant mass flow, vapor quality, star-shaped fin, oil concentration and volume fraction of nanoparticles are studied. SiO2–TiO2 nanoparticles are synthesized by applying both ultra-sound irradiation and sol–gel methods. Morphology and size of nanostructures are portrayed through the exact use of scanning electron microscopy, while the phase of the product is investigated by an X-ray diffraction pattern (XRD). The findings indicate that as the mass flow enhances, the heat transfer coefficient rises. The heat transfer coefficient and pressure drop have increased by using a helical fin. Regarding the oil-refrigerant mixture, the heat transfer coefficient augments at low vapor quality and reduces at high vapor quality. By adding nanoparticles, heat transfer increases, but a decreasing trend in heat transfer is observed from a certain vapor quality. The highest percentage of increase in heat transfer at a mass velocity of 380 kg/m2.s is for the case with a fin and a mixture of R134a/nano oil, and this amount is equal to 89%.

Compression refrigeration cycle is widely used in air conditioning and cooling industries. Energy saving and improving refrigeration cycle performance are very important. Improving the thermal properties of the refrigerant and changing the structure of the evaporator are some of the ways to increase the cooling capacity and performance of the refrigeration cycle. In the present study the impact of utilizing aluminum spiral-star fins in the evaporator and R134a-nanooil on the performance of a vapor compression refrigeration cycle is experimentally investigated. Evaporator is a shell-tube heat exchanger in which water flows in the shell side and refrigerant flows in the tube side. SiO2–TiO2 nanoparticles were chosen and synthesized by sol–gel procedure that was assisted with sono-chemical irradiation. Scanning electron microscopy (SEM) depicts morphology and size of the nanostructures, also X-ray diffraction pattern (XRD) analyzes phase of the nanoparticles. Refrigerant mass flow rate is in the range of 0.9–2.1 kg min−1, while different concentrations are considered for SiO2–TiO2-oil including 0.05, 0.1, 0.2 and 0.3 percent. The results revealed that addition of nano-oil can improve heat transfer coefficient by 56% and coefficient of performance (COP) of cycle by 8% maximally. Furthermore, installing aluminum fins in the evaporator tubes can enhance heat transfer coefficient by 80% and COP of cycle by 16.4% maximally and using nano-oil/fins can increase heat transfer coefficient and COP by 155% and 25%, respectively.

The closed-cell aluminum alloy foams were fabricated by the molten body transitional foaming process. In this research, the closed-cell aluminum foams were successfully fabricated with different zinc contents (4, 8, and 12wt%) using the melt-foaming method and blowing agents. Calcium was used to increase the melt viscosity and CaCO3 was used as a foaming agent. Uniaxial compressions tests were performed on the foams to investigate the effects of zinc addition on the mechanical behavior of fabricated Al–Zn foams. The effects of zinc additions on the foam properties such as density, porosity, pore diameter, yield strength, plateau stress, and energy absorption were investigated. According to the X-ray analysis results, the reaction between Al–Ca–Zn leads to the formation of oxide phases in the melt and increases the melt viscosity and also the cell wall thickness. Foam with 4wt% Zn has a good yield strength and longer plateau region than pure aluminum foam due to the uniform cell structure. The foam density and the absorbed energy per unit volume of Al–Zn foams increase with increasing zinc content to foams.

This paper presents the hardware implementation of a digital solar array simulator (DSAS) to evaluate and validate the operation of maximum power point tracking (MPPT) algorithms and photovoltaic (PV) inverters used in solar power conditioning systems (SPCSs). The required criteria for designing and setting up a genuine SAS are high-accuracy static behavior, fast transient response, and high flexibility for the emulation of the different PV modules. A four-phase interleaved buck converter is chosen as the proposed power stage of the SAS because of its advantages of power management, filtering reduction requirements, and output ripple minimization. The proposed SAS control system has been digitally implemented by a digital signal processor (DSP)-based controller, in which third-order integral-lead compensator and resistive feedback method have been chosen to reproduce precise and stable operating points. Experimental results confirm the proper and satisfactory steady-state operation and dynamic response of the proposed DSAS.

A new structure for the compression surfaces of a supersonic inlet is proposed which has improved the target performance parameter i.e. total pressure recovery ratio. This idea resulted in development of a new type of supersonic inlet, utilized four ramps and a cone simultaneously as the compression surfaces. A prototype of the proposed inlet has been designed for a free stream Mach number of 3 and its performance has been evaluated via numerical simulation for both design and off-design conditions. The performance of the newly designed inlet has been compared to the existing experimental data of two double-cone inlets. The acquired data are further compared with analytical calculations of maximum reachable TPR for some conventional supersonic inlet types. The results confirmed the effectiveness of the main idea of the proposed design methodology. The total pressure recovery ratio of the newly designed inlet at its design condition, M ∞ = 3 , is calculated to be 76.8%.

High-altitude test facilities are usually used to evaluate the performance of space mission engines. The supersonic exhaust diffuser, a main part of high-altitude test facility, provides the required test cell vacuum conditions by self-pumping the nozzle exhaust gases to the atmosphere. However, the plume temperature is often much higher than the temperature the diffuser structure is able to withstand, usually above 2500 K. In this study, an efficient cooling system is designed and analyzed to resolve the thermal problem. A water spray cooling technique is preferred among various existing techniques. Here, a new algorithm is developed for a spray cooling system for a supersonic exhaust diffuser. This algorithm uses a series of experimental and geometrical relationships to resize the governing parameters and remove the required heat flux from the diffuser surface. The efficiency of the newly designed cooling system is evaluated via numerical simulations. The utilized numerical technique is based on the discrete-phase method. Various computational studies are accomplished to enhance the accuracy of numerical prediction and validation. The present numerical study is validated using experimental results. The results show that the realizable k-ɛ method is superior compared to other Reynolds-averaged Navier–Stokes models.

Feasibility of an innovative buzz detection technique through measuring the static pressure outside a mixed-compression supersonic inlet is studied. The buzz is an instability phenomenon that occurs almost in all supersonic inlets. During the buzz, shock oscillation along with pressure and mass flow fluctuations affects the performance characteristics of the inlet. The main objective of this paper is to introduce a simple and easy-to-implement method for investigation of the buzz phenomenon in a supersonic inlet. The experimental data for far field-based are compared with those of the model-based one at free stream Mach numbers of 1.8, 2.0, and 2.2 and at zero degrees angle of attack for a mixed-compression inlet. The results show that this technique can measure exact value of buzz frequency as well as its onset. The present method uses pressure data obtained from the wind-tunnel wall instead of measuring the pressure inside or on the model surfaces which in most cases is very hard. However, to sense flow oscillations, caused by the buzz onset the sensors on the wind-tunnel wall must be located downstream of the point where the oblique shock from the spike impinges on the tunnel wall. The location of the measurement point as well as the distance between the sensor and the origin of the shock wave system are very important.

The massive volume of comments on websites and social networks has made it possible to raise awareness of people's beliefs and preferences regarding products and services on a large scale. For this purpose, sentiment analysis, which refers to the determination of the sentiment of texts, has been proposed as an intelligent solution. From a methodological point of view, the recent combination of words embedding and deep neural networks (DNNs) has become an effective approach for sentiment analysis. In Persian studies, formal corpuses such as Wikipedia dumps have been used for word embedding. The fundamental difference between formal and informal texts means that the vectors derived from formal texts in informal contexts such as social networks do not result in desirable accuracy. To overcome this drawback, in this paper, we provide a large integrated text corpus of several different sources of informal comments and we also utilize the Fasttext as the word embedding algorithm. In this research, we use Attention-based LSTM, which has been shown to perform more effectively compared to the similar methods in sentiment analysis for the English language. The proposed method is evaluated on the two Persian “Taaghche” and “Filimo” datasets collected in this paper. The experiments on the two Persian datasets prove that utilizing informal vectors in sentiment analysis and applying the attention model improves the prediction accuracy of the DNN in the sentiment analysis of Persian texts.

Statement of the problem Headgear is most commonly used to correct anteroposterior discrepancies. Headgear can also be used to make more space for teeth to come in. In this instance the headgear is attached to the molars, via molar headgear bands and tubes, and helps to draw these molars backwards in the mouth, opening up space for the front teeth to be moved back using braces and bands. Stress on PDL of molars teeth and soreness of teeth when chewing, or when the teeth touch, is typical. Adults usually feel the soreness 12–24 h later, but younger patients tend to react sooner. Purpose Application of heavy forces to maxillary dentition during treatment with headgear, induces high concentration of stresses in periodontal tissue. Quantification of this stress is of great concern in orthodontics. This study was designed to investigate the quantity and quality of stress response in the PDL of maxillary first molar which was subjected to highpull headgear traction using Finite Element Method. Materials and method In an experimental study, a three-dimensional finite element model of maxillary dentition, consisting of 17096 elements & 23013 nodes, was developed based on a young human skull. The forces were applied to the maxillary first molar in the stabilized arch by means of a rectangular full size arch wire in (022) slot bracket. Mechanical properties of this model were based on previous studies. A 350 g force was used for high pull headgear to affect the dentition (+30°) and stress distribution was investigated in buccal, palatal, mesial and distal side and in cervical, middle, apical sections of the PDL. The quantity of stresses were expressed as principal stresses, while the negative and positive signs indicated compressive and tensile stresses respectively. Results The buccal surface of PDL of mesiobuccal root and the buccal, palatal, and distal surface in cervical regions of PDL of distobuccal root and the distal surface of the PDL of palatal root had received a great deal of stresses, in addition, the over all stress distribution in roots of molar had intrusive nature. Conclusion The distribution of high stress concentration areas observed after using high pull headgear is limited to some root surfaces specially the distobuccal root.

Previous studies report positive effects of pentoxifylline (PTX) alone or in combination with other drugs on some pathologic bone diseases as well as an ability to accelerate osteogensis and fracture healing in both animal models and human patients. The aim of this present study was to evaluate the effects of PTX administration on Hounsfield unit and bone strength at catabolic response (bone resorbing) of a fracture in an experimental rat model of ovariectomy induced osteoporosis (OVX-D). Thirty adult female rats were divided into groups as follows: 1 (OVX, control, no treatment); 2 (OVX, sham: daily distilled water); 3 (OVX, daily alendronate: 3 mg/kg); 4 (OVX, twice daily 100 mg/kg PTX) and 5 (OVX, PTX+alenderonate). OVX was induced by bilateral ovariectomy in all rats. A complete standardized osteotomy of the right femur was made after 3.5 months. PTX and alendronate treatments were performed for eight weeks. Then, rats were euthanized and had its right femur subjected to computerized tomography scanning for measuring Hounsfield unit; eventually, the samples were sent for a three point bending test for evaluation of the bone strength. Administration of PTX with 200 mg/kg and alendronate alone and in combination showed no significant alteration in Hounsfield unit and biomechanical properties of repairing callus of the complete osteotomy compared with the control group. Results showed increased bending stiffness and stress high load mean values of repairing complete osteotomy in PTX-treated rats compared to the control OVX-D.

The present research is devoted to theoretical study of the pull-in performance of double-sided and paddle-type NEMS actuators fabricated from cylindrical nanowire operating in the Casimir regime and in the presence of the centrifugal force. D'Alembert's principle was used to transform the angular velocity into an equivalent static, centrifugal force. Using the couple stress theory, the constitutive equations of the actuators were derived. The equivalent boundary condition technique was applied to obtain the governing equation of the paddle-type actuator. Three distinct approaches, the Duan-Adomian Method (DAM), Finite Difference Method (FDM), and Lumped Parameter Model (LPM), were applied to solve the equation of motion of these two actuators. This study demonstrates the influence of various parameters, i.e., the Casimir force, geometric characteristics, and the angular speed, on the pull-in performance. (C) 2017 Sharif University of Technology. All rights reserved.

This study aims at investigating the impact of oil price and exchange rate uncertainty on stock returns in Tehran Securities Exchange (TSE). To this end, "oil price uncertainty" and "exchange rate uncertainty" are considered as independent variables and "return on stocks" as the dependent variable. Daily data on the price of heavy oil, official exchange rate and Tehran Exchange Price Index (TEPIX) are used from 1 January 2002 to 31 December 2012. To evaluate the impact of oil price and exchange rate uncertainty on stock returns, the uncertainty is measured using Whitening Linear Transformation method and is estimated using the Vector Auto Regressive model. Results of the estimations of the model show that there is a significant relation between the uncertainty of oil price and stock returns and another between the uncertainty of exchange rate and stock returns. Thus, the hypothesis of this study are confirmed by the error level of 0.05

Effects of various boundary-layer bleed locations on the stability of an axisymmetric supersonic inlet has been investigated experimentally. The bleeds were located on the inlet compression cone and were designed to improve the stability margin of the inlet. The main objective of the study was to identify the boundary-layer bleed location and its effects on the improvement of the stability margin of the inlet. In addition, a buzz precursor detection methodology based on the rms level has been introduced. Experiments have been carried out on a mixed-compression inlet with a design Mach number of 2.0 and three different bleed locations at three freestream Mach numbers of 1.8, 2.0, and 2.2. All tests were conducted at an angle of attack of 0 deg. The results show that, based on the individual design of an inlet, a location can be found that the spilled normal shock stands at this location and consequently separation starts at the buzz onset. If the bleed slot is located in this place, the subcritical perform...

Free or restricted shock separation phenomena can occur inside a thrust optimized parabolic (TOP) nozzle during over-expanded operations. In the case of restricted shock separation, a cap shock pattern forms in the nozzle which leads to a substantial total pressure drop. This induces further related issues in the process of ground testing of such nozzles using a second throat exhaust diffuser (STED). In the present study, the flow physics in several TOP nozzles operating at over-expanded conditions is investigated numerically. At first, the strong effect of the initial expansion angle of a TOP nozzle on flow separation pattern and shock structure is demonstrated. Results reveal that for high initial expansion angles, restricted shock separation occurs even at low nozzle pressure ratios, while free shock separation takes place for small initial expansion angles at even high nozzle pressure ratios. Subsequently, the effect of separation patterns in TOP nozzles on the starting pressure of a STED is studied. Current results show that the presence of a restricted shock separation pattern leads to a considerable increment of the critical cross sectional area of the flow inside the diffuser. Therefore, the minimum starting pressure of the STED is increased up to 30% after the resizing of the second throat area to eliminate the flow choking inside it.

The performance and the buzz onset of a supersonic mixed-compression axisymmetric intake are experimentally investigated. Effects of the slot bleed position, angle, and width on the intake performance and on the buzz initiation at three different Mach numbers of 1.8, 2.0, and 2.2 and at a zero degree angle of attack are studied. The intake performance is assessed using the total pressure recovery, mass flow ratio, flow distortion, and bleed mass flow ratio. The results show that applying the bleed at a position near the intake entrance and reducing the bleed entrance slant angle and width all improve the intake performance considerably. Moreover, these parameters postpone the buzz onset. In addition, it is found that the vertical position of the intersection point of the barrier and normal shocks plays an important role in the intake pressure recovery.

An extensive experimental investigation was performed to explore the shock waves formation and development process in transonic flow. Shadowgraph visualization technique was employed to provide visual description of the flowfield features. Based on the visualization, the formation process was categorized into two intrinsically different phases, subsonic and supersonic. The characteristics of subsonic phase are well known; however, those of the supersonic ones are far less studied. The supersonic phase itself is made up of two consecutive phases, namely approaching and sweeping. The effects of each phase on the flowfield characteristics and on shaping the supersonic regime have been studied in details. In order to generalize the results, three different models were tested. Moreover, a special terminology is suggested by authors to ease the process description and to pave a way for future studies. Above all, as the transition from transonic regime to supersonic one is a vague concept in terms of physical reasoning, a new explanation was proposed that could be used as a criterion for distinguishing between transonic and supersonic regimes.

Objective Unexplained syncope is a challenge facing electrophysiologists. The prognosis varies widely depending on underlying causes, specially, cardiac ones. We sought to determine the abnormal electrophysiolgic (EP) study results as predictors of prognosis in syncope patients with suspected cardiac cause and risk factors associated with mortality. Methods A total of 227 consecutive patients with unexplained syncope were prospectively enrolled in this study. EP study was performed in 177 patients in base of inclusion criteria. These patients, in whom a cardiac cause of syncope was suspected, underwent EP study and if negative, head-up tilts test (HUTT). Complete follow-up was obtained for 132 patients for 20.0±10.8 months. Results A cardiac cause of syncope was established in 35%, a neurally mediated syncope in 35.6%, and in the rest 29.4% the cause of syncope remained unexplained despite a throughout neurologic and cardiologic evaluation. Logistic analysis revealed that the significant predictors of a cardiac cause of syncope were the absence of prodromal symptoms, left bundle branch block (LBBB), sever left ventricle (LV) dysfunction and male gender. At logistic analysis, the presence of LBBB (OR=6.63; 95% CI: 1.09-40) was significantly associated with outcome of death. Conclusion The present study provides evidence that presence of LBBB, abnormal EP study result and structural heart disease (SHD) have prognostic value in patients with suspected cardiac cause of syncope. The patients with SHD and unexplained syncope who had a negative EP study have a good long-term prognosis even in the presence of LV dysfunction.

Anaxisymmetric supersonic inlet was tested to study the influence of angle of attack andmass flow rate on the inlet buzz phenomenon at a freestreamMach number of 2 and at various angles of attack 0–10 deg. For each angle of attack, two main frequencies for the buzz were seen in the data. For the moderate mass flow rates, small-amplitude and high-frequency oscillation occurred. In this operation stage, both highand low-frequency oscillations exist, but the higher one is dominant and is very close to the frequency of the second acoustic resonance mode. At lower mass flow, however, low-frequency and large-amplitude oscillation occurred that had a single frequency with a constant period. Increasing the angle of attack decreased the inlet performance and limited the stability margin. At intermediate values of themass flow, the buzz frequencywas seen to be independent of the angle of attack, but, for the lower mass flow rates and at high angles of attack, the frequency of the buzz at front portions of the inlet varied. However, the diffuser end still has a constant frequency. In addition, the total-pressure signal had behavior similar to that of the static data with approximately the same frequency.

A computational fluid dynamics code was developed to compute the flow inside and around a supersonic external compression axisymmetric intake. The code solves the Reynolds-averaged Navier–Stokes equations using an explicit finite volume method in a structured grid and uses the Baldwin–Lomax algebraic model to compute the turbulent viscosity coefficient. Experiments were performed to validate the predicted results and good agreements are achieved. In the next part of the research, a parametric study was undertaken using the designed base case at a constant Mach number of 2 and at 0° angle of attack. The effects of various important parameters such as free stream Mach number, spike deflection angle, and back pressure ratio on the total pressure recovery, mass flow ratio, flow distortion, and drag coefficient of the intake were then numerically investigated. The results showed that when the spike deflection angle of the intake was changed from 28° (designed base case) to 30°, the intake drag coefficient was reduced up to 9%. In addition, the intake performance degraded for very low values of the back pressure ratio.

The performance characteristics of an axisymmetric inlet at its design and off-design operational conditions are experimentally investigated. The model is tested for wide ranges of free stream Mach numbers, M∞ = 1.5–2.5, and mass flow rates. For each test, the pressure recovery, the mass flow passing through the inlet and the pressure distribution over the spike and the cowl are measured. In addition, the shock wave formed in front of the inlet is visualized. The characteristic curve of the inlet is then obtained for each free stream Mach number. As the Mach number is increased, the pressure recovery is reduced, but the maximum value of the mass flow rate grows up. Variations of the mass flow affect the surface pressure over both the front portion of the cowl and the entire surface of the spike. Further, it has changed both pressure and Mach number at the end of the diffuser, which would consequently affect the performance of the propulsion system. In addition, contrary to the internal boundary layer, the external one far from the cowl lip has been found to be almost independent of the inlet mass flow rate for a constant free stream Mach number.

A numerical code for supersonic intake design with a proper simulation of the normal and/or oblique shocks, boundary layer development, interaction of the shock and the boundary layer, as well as prediction of the flow separation is of great help to the designers. In this research, a numerical code is developed to solve the inner and outer flow fields of the intake and validated with various experimental tests. The intake is an axisymmetric external compression one. Roe scheme and new schemes, AUSM+-up (for all speed) and Advection Upstream Splitting Method with Pressure-Based Weight function (AUSMPW), are used to compute the convective fluxes. The original version of the AUSMPW scheme has serious problems concerning the stability and accuracy. In this investigation, several modifications are implemented to the original version of the AUSMPW scheme for the first time which resulted in a better stability and accuracy. Turbulent viscosity coefficient is computed using the Baldwin–Lomax algebraic model. The numerical results are compared well with the experimental data. It is further found that the Roe scheme has the best accuracy; however, the AUSM+-up (for all speed) scheme is numerically very efficient.

An extensive wind tunnel tests were conducted on an axisymmetric supersonic inlet at Mach numbers from 1.8 to 2.2 and at different values of mass flow rates. Frequencies of the buzz were achieved from the pressure data as well as the high speed shadowgraph pictures. For each Mach number, two main frequencies for the buzz were obtained. The inlet at its design condition was stable, but when the mass flow rate was reduced, at first the shock wave started to oscillate with a small amplitude which is matched the Ferri criterion (little buzz). In this situation, both high- and low-frequency oscillations occurred; however, the high frequency one was dominant, but the oscillations seemed to be irregular. By further decreasing the inlet mass flow, the shock oscillations got a single low frequency and high amplitude, which in agreement with the Dailey criterion (big buzz). At a free stream Mach number of 2.2, the frequencies of these two kinds of instabilities are about 554 and 137 Hz, respectively. At this Mach number for moderate mass flow, an oscillation with high frequency/large amplitude and constant period was observed. The oscillation has the combined characteristics of the little buzz and the big buzz, which is named “added buzz” here. It is shown that at fairly constant mass flow, the frequency of the buzz is independent of the Mach number. It is further found that the buzz instability affects the external flow as well as the internal one with the same frequency.

An experimental study was carried out on an axisymmetric supersonic inlet with external compression. The scope of this study was to investigate the general characteristics of the inlet buzz under various design and off-design conditions. The model was equipped with accurate and high frequency pressure sensors and the tests were conducted at Mach numbers varying from 1.8 to 2.5, at various angles of attack, and at different mass flow rates. Shadowgraph flow visualization, together with a high speed camera, was used to capture the external shock structure in front of the inlet. Frequencies of buzz were obtained from both the shadowgraph pictures and analysis of the pressure data. The amplitude of the shock wave motion was measured from the visualization pictures, too. The results show that for low mass flow rates, buzz frequency is almost independent of Mach number, while at a higher mass flow rate, the frequency of the shock oscillation increases with Mach number. Further, for each free stream Mach number, as the mass flow rate decreased, the amplitude of the shock movement grew, but its frequency decreased.

Background: Globally, musculoskeletal injuries comprise a major public health problem that contributes to a large burden of disability and suffering. Pentoxifylline (PTX) has been originally used as a hemorheologic drug to treat intermittent claudication. Previous test tube and in vivo studies reported the beneficial effects of PTX on bony tissue. Objectives: This study aims to evaluate the effects of different dosages of PTX on biomechanical properties that occur during the late phase of the fracture healing process following a complete femoral osteotomy in a rat model. We applied intramedullary pin fixation as the treatment of choice. Materials and Methods: This experimental study was conducted at the Shahid Beheshti University of Medical Sciences, Tehran, Iran. We used the simple random technique to divide 35 female rats into five groups. Group 1 received intraperitoneal (i.p.) PTX (50 mg/kg, once daily) injections, starting 15 days before surgery, and group 2, group 3, and group 4 received 50 mg/kg, 100 mg/kg, and 200 mg/kg i.p. PTX injections, respectively, once daily after surgery. All animals across groups received treatment for six weeks (until sacrificed). Complete surgical transverse osteotomy was performed in the right femur of all rats. At six weeks after surgery, the femurs were subjected to a three-point bending test. Results: Daily administration of 50 mg/kg PTX (groups 1 and 2) decreased the high stress load in repairing osteotomized femurs when compared with the control group. The highest dose of PTX (200 mg/kg) significantly increased the high stress load when compared with the control group (P = 0.030), group 1 (P = 0.023), group 2 (P = 0.008), and group 3 (P = 0.010), per the LSD findings. Conclusions: Treatment with 200 mg/kg PTX accelerated fracture healing when compared with the control group.

The present research was an attempt to see how Quranic Divine Names (DNs) were translated into English by three professional translators namely, Shakir (1985), Qarai (2003), and Nikayin (2006) who provided their translations in prose, phrase-by-phrase, and poetry forms respectively. Firstly, the problems which the translators met for attaining lexical adequacy and semantic equivalence were explored. Secondly, the type and extent of strategies adopted by these three translators for overcoming the problems were described. Finally, the translators` works were compared and implications drawn. The findings of the study showed that the lexical compression of the original DNs and their emotive overtones and effects caused the main body of problems for the translators. Furthermore, it was found out that the most frequent strategies adopted by Shakir and Qarai were ‘near-synonymy’ and ‘expansion’ respectively. Nikayin, however, used these two strategies almost to an equal extent as his most frequent strategies.

An extensive wind tunnel test series were conducted on an axisymmetric supersonic inlet. The model was tested at Mach numbers from 1.8 to 2.2 and at different values of mass flow rate. Shadowgraph flow visualization was used to capture the external shock structure in front of the inlet. The goal of this study is to find out the general characteristics of the inlet buzz. Frequencies of the buzz have been achieved from the analysis of the pressure data as well as the shadowgraph pictures. The amplitude of the shock waves motion has been measured from the visualization pictures too. In the some large value of mass flow rate, the frequency of shock oscillation increased versus Mach number. Also in each Mach number due to the mass flow rate decrement, the buzz frequency decreases and its amplitude increases conversely. Also buzz instability affects the external flow by the same frequency of the internal one.Copyright © 2010 by ASME

Heat source addition to the axisymmetric supersonic inlet may improve the performance parameters, which will increase the inlet efficiency. In this investigation the heat has been added to the flow field at some distance ahead of an axisymmetric inlet by adding an imaginary thermal source upstream of cowl lip. The effect of heat addition on the drag coefficient, mass flow rate and the overall efficiency of the inlet have been investigated. The results show that heat addition causes flow separation, hence to prevent this phenomena, roughness has been added on the spike surface. However, heat addition reduces the drag coefficient and the inlet mass flow rate considerably. Furthermore, the effects of position, size, and shape on the inlet performance were studied. It is found that the thermal source deflects the flow streamlines. By improper location of the thermal source, the optimum condition has been obtained. For the optimum condition, the drag coefficient is considerably reduced and the inlet mass flow rate and its efficiency have been increased slightly. The optimum shape of the heat source is obtained too., {"references":["J. Roskam, Airplane Design, Part 6. Ottawa: Roskam Aviation and\nengineering Corporation, 1987, pp. 159-164.","E. L. Goldsmith, J. Seddon, Practical Intake Aerodynamic Design.\nLondon: Blackwell Scientific Publications, 1993.","H. Kobayash et al., \"Study on variable-shape supersonic inlets and\nmissiles with MRD device,\" ScienceDirect, 2006, pp. 1-11.","S. O. Macheret, M. N. Shneider, R. B. Miles, \"Scramjet inlet control by\noff-body energy addition: a virtual cowl,\" 41st AIAA Aerospace\nSciences Meeting and Exhibit, Reno, Jan. 2003, pp. 1-19.","I. G. Girgis, M. N. Shneider, S. O. Macheret, G. L. Brown, R. B. Miles,\n\" Steering moments creation in supersonic flow by off-axis plasma heat\naddition,\" Journal of Spacecraft and Rockets, vol. 43, no. 3, May-June\n2006, pp. 607-613.","B. McAndrew, J. Kline, R. B. Miles, \"Aerodynamic control of a\nsymmetric cone in compressible flow using microwave driven plasma\ndischarges,\" 41st AIAA Aerospace Sciences Meeting and Exhibit, Reno,\nJan. 2003, pp. 1-8.","R. B. Miles et al., \"Plasma control of shock waves in aerodynamics and\nsonic boom mitigation,\" 32nd AIAA Plasmadynamics and Lasers Conf.\nand 4th Weakly Ionized Gases Workshop Conf. & Exhibit, Anaheim,\nCA, June 2001, pp. 1-13.","K. Kremeyer, \"Lines of pulsed energy for supersonic/hypersonic drag\nreduction: generation and implementation,\" AIAA-2004-0984, 2004, pp.\n1-11.","M. R. Soltani, M. Taiebi-Rahni, M. Farahani, M. R. Heidari, \"Flow\nmeasurements around a long axisymmetric body with varying cross\nsection,\" AIAA-05-50, 2005."]}

The flow over a supersonic inlet has been investigated experimentally and numerically at a free stream Mach number of 2 and a zero degree angle of attack. Wind tunnel tests were performed to obtain the performance parameters of the inlet and were used as a baseline and validation tools for the numerical code. A heat source was added to the flow field at a distance ahead of the inlet. The effect of heat source addition on the main performance parameters of the inlet is investigated numerically. Results show that the heat source considerably reduces drag coefficient; however, its effect on pressure recovery is not favorable. This unfavorable effect was then minimized by controlling heat source parameters, such as its location, size and shape. For the optimum condition, drag coefficient reduces considerably, inlet mass flow rate increases, but pressure recovery slightly decreases.

It is well recognized that size-e ect often plays a signi cant role in the mechanical performance of nano-structures. Herein, strain gradient continuum elasticity is employed to investigate the size dependent pull-in instability of the cantilever nanoactuators immersed in ionic liquid electrolyte. The presence of dispersion forces, i.e. Casimir and van der Waals eld, is considered in the theoretical model as well as the double-layer electrochemical attraction. To solve the non-linear constitutive equation of the system, two approaches, i.e. the Rayleigh Ritz Method (RRM) and the numerical solution method, are employed. Impact of the size dependency and dispersion forces on the instability characteristics are discussed as well as the e ect of ion concentration in liquid.