فهرست مطالب

International Journal of Engineering
Volume:30 Issue: 10, Oct 2017

  • TRANSACTIONS A: Basics
  • تاریخ انتشار: 1396/08/07
  • تعداد عناوین: 23
|
  • P. Ghasemian, E. Abdollahzadeh Sharghi*, L. Davarpanah Pages 1417-1424
    In this work, the performance of organic pollutant removal, membrane fouling and sludge morphology in a submerged membrane bioreactor (MBR) treating sunflower oil refinery wastewater (SORW) containing high oleic content was studied during 52 days’ operation at short values of 18 h and 10 days for hydraulic retention time and sludge retention time, respectively. The removal efficiencies of chemical oxygen demand (COD), oil and grease (O&G) and turbidity were found to be 73.2±6.6%, 75.1±2.5%, and 99.7±0.1%, respectively and the need for membrane cleaning never rose. The results showed a statistically significant linear correlation between the mixed liquor O&G with soluble microbial products and extracellular polymeric substances (EPS) (rP=0.792; p-value=0.034 and rP=0.920; p-value=0.003, respectively). Additionally, increase in MLVSS concentration which was due to an increase in cell concentration and was not related to accumulation of O&G and biopolymers inside the bioreactor, increased specific oxygen uptake rate. The trend of changes in sludge volume index (SVI) and supernatant turbidity (ST) with EPStotal was also found to be statistically significant (rP=0.736; p-value=0.037 and rP=0.773; p-value=0.024, respectively). The results of SVI, ST, EPS, particle size distribution and microscopic observation showed change in sludge morphology to flocs of smaller size (unimodal, with mode of 20 μm) with high compressibility (SVI=44.0 mL g–1 MLSS) and bioflocculating ability (ST=20.4±3.3 NTU). The results of the present study were indicative of a very good potential of the MBR for treatment of SORWs.
    Keywords: Membrane Bioreactor, Sunflower Oil Refinery Wastewater, Sludge Retention Time, Hydraulic Retention Time, Morphology, Extracellular Polymeric Substances
  • F. Gholami, S. Zinadini, A. A. Zinatizadeh*, E. Noori, E. Rafiee Pages 1425-1433
    Graphene oxide/Ag nanoparticles (Ag/GO) was prepared and employed to synthesize antifouling polyethersulfone (PES) mixed matrix membranes. The performance of the membranes was evaluated in terms of flux, hydrophilicity and anti-biofouling properties. With increment of the Ag/GO from 0 to 0.1 wt.%, the pure water flux increased from 24.7 up to 54.1 kg/m2 h. The flux recovery ratio (FRR) of the membranes was performed using milk powder solution and the results illustrated that the 0.1 wt.% Ag/GO membrane had the best fouling resistance with the FRR value of 95.45%. The performance of the nanofiltration was assessed using the retention of Direct Red 16. It was indicated that the Ag/GO-PES membranes have remarkable dye removal (98.38% rejection). The anti-biofouling activities of the 0.1 wt.% Ag/GO mixed matrix membrane was also investigated using activated sludge and the results showed a notable improvement.
    Keywords: Graphene Oxide, Ag Nanocomposite, Polyethersulfone Nanofilteration Membrane, Hydrophilicity, Anti, biofouling
  • N. Roshan*, S. Ghader, M. R. Rahimpour Pages 1434-1442
    A theoretical model is developed to consider the effect of demulsifier agent on demulsification of water-in-crude oil emulsion. A thermodynamic approach is considered to correlate the critical micelle concentration of a demulsifier to the collision frequency function in population balance equation (PBE). Based on the proposed correlation, the collision frequency function is modified to account the effect of demulsifier agent on water droplets coalescence. The water separation capability of a selected group of demulsifiers is investigated via the conventional bottle test method to obtain the adjustable parameter of the developed equation so that the absolute relative error of predicted demulsification efficiency and experimental data are considered as objective. Comparison between the model simulated results and the experimental data showed that the proposed model could appropriately reproduce the experimental data at different agent concentrations.
    Keywords: Demulsifier, Critical Micelle Concentration, Population Balance Equation, Collision Frequency
  • F. Behnamfar*, A. Fathollahi Pages 1443-1450
    Design spectrum is known as an essential tool in earthquake engineering for calculation of maximum (design) responses in a structural system. Soil-structure interaction (SSI), as a phenomenon of coupling of responses of a structure and its underlying soil, was explored after introduction of design spectra and has not been taken into account in developing a design spectrum traditionally. To consider the SSI automatically when doing a spectrum analysis, in this paper maximum response of a single degree of freedom system resting on a flexible base is determined under consistent earthquakes. Consistency of earthquakes is maintained by considering their magnitude, distance, local soil type, and return period. The latter parameter is accounted by the use of earthquake categories identified by their similar spectral values at short periods. Different types of soils and two categories of earthquakes regarding their distance, being near field and far field, are considered. The results are presented as smoothed design spectra. It is shown that SSI alters the response acceleration of buildings having up to about 10 stories and is ineffective for the rest. It has an increasing effect for the response acceleration of buildings up to about 5 stories.
    Keywords: Design Spectrum, Soil, structure Interaction, Earthquake Record, Dynamic Analysis
  • M. Abdollahi, J. Bolouri Bazaz* Pages 1451-1463
    Air pluviation is a method of preparing laboratory models to carry out many geotechnical experiments. In this study, a new air pluviation device has been developed by the researchers. For laboratory modeling, it is important to calibrate the device using air pluviation to produce accurate specimens with desirable conditions and relative densities. A series of laboratory tests were conducted to evaluate the performance of the proposed system. The main features of the rainer system used in this study are the selection of two identical diffuser sieves and three series of curtain-type rainer of different diameters at constant reciprocating speed of the device during sand pluviation in the embedded rails. The results show the ability of this method in producing sand specimens for laboratory models in relative densities of 28 to 103%, which can produce sands of uniform conditions of loose to very dense at 1.0 to 4.1 m drop height. Also, according to the results of the experiments, it can be stated that by reducing the diameter of the rainer curtain, soil density of modes covering in small range. The results also reveal that the use of diffuser sieves can produce specimens of extremely high density. For the purpose of the design, construction and efficiency control of this device proposed in this paper, numerous experiments and studies have been undertaken. It is noteworthy to mention some innovative aspects of this device. The first feature of this device is producing specimen with desirable relative density in a wide range of relative density modes. Another outstanding feature of this device is the horizontal and vertical uniformity of the reconstituted specimen with an error of less than 7%.
    Keywords: Rainer System, Drop Height, Diffuser Sieves, Rainer Curtain, Relative Density
  • S. Borzouyi Kutenayi, S. R. Kiahosseini*, M. H. Talebpour Pages 1464-1470
    Many parameters are influenced by the diffusion of chloride on concrete in marine environments and these can affect concrete quality. In this study, the effect of water to cement ratio of 0.35, 0.40 and 0.45 on corrosion resistance and compressive strength of reinforced concrete was evaluated. Moreover, different percentages of micro silica (SiO2) including 5, 7.5 and 10% were utilized, in order to investigate the effect of pozzolanic materials on the corrosion of steel in concrete. Then cubic samples reinforced with steel bar spacing of 2.5, 5 and 7 cm from the cube surface were made and put in Caspian sea water for 5 months. During this period, corrosion potential of steel was measured by a calomel half cell (SCE). In order to finalize the evaluation of the mechanical strength of the samples, concrete pressure test was conducted and the result showed that after 40, 44 and 59 days for the bars with depth of 2.5, 5 and 7 cm, respectively and the samples prepared with water-cement ratio of 0.35, the corrosion potential was -350V versus SCE, while the compressive strength was approximately 450 kg/cm2. This result showed longer life span of this sample in comparison with other water-cement ratios. By adding micro silica to the samples up to 7.5%, the time for obtaining a corrosion potential of -350V, bars with depth of 2.5, 5 and 7 cm, was 43, 50 and 86 days, respectively, and the compressive strength of this sample was approximately 480 kg/cm2. Consequently, it is arguable that in order to achieve longer life span of corrosion and suitable compressive strength, the optimum ratio of water to cement should be 0.35 and the percentage of pozzolan SiO2 should be 7.5%.
    Keywords: Chloride, Corrosion Potential, Steel Corrosion, Micro silica
  • X. Zhou, L. Bai, C. Wang* Pages 1471-1478
    The sky regions of foggy image processed by all the existing conventional dehazing methods are degraded by color distortion and severe noise. This paper proposes an improved algorithm which combines dark channel prior and inverse image. We first invert the foggy image, and then estimate the transmission of the inverse image. At last, compared with the non-inversed transmission, the larger values of the transmission are the final transmission. This algorithm tends to refine the medium transmission by adjusting the values of pixels in the bright region to meet the hypothesis of dark channel prior. The method is viable to eliminate color distortion of the dehazed image.
    Keywords: Image Dehazing, Haze Removal, Dark Channel Prior, Inverse Image
  • F. Asadi Saeed Abad, H. Hamidi* Pages 1479-1486
    The issue of online privacy and security is a challenging subject, as it concerns the privacy of data that are increasingly more accessible via the internet. In other words, people who intend to access the private information of other users can do so more efficiently over the internet. This study is an attempt to address the privacy issue of distributed big data in the context of cloud computing. One of the cases where data privacy is of great importance is the authentication and protection of ownership data. In this paper, this privacy issue is analyzed by Petri net modeling. What today’s organizations need for their clouds are integrated comprehensive solutions that can deliver security intelligence. Advanced security intelligence solutions can close security gaps by using labor-saving automation to analyze millions of events occurring within the cloud, and discover system vulnerabilities through the normalization and correlation of these events. Using the proposed method, a model of security, including control of user access to databases of big data with RMS, the multiplicity and the virtual machine to prevent internal threats, deleting data, insecure or incomplete data protection and control of a third-party can be provided to improve the operation according to the rules of Petri net modeling and simulation.
    Keywords: Big Data, Privacy, Security Model, Petri Net, Cloud Computing
  • H. P. Patra*, K. Rajnish Pages 1487-1493
    We can say a software project is successful when it is delivered on time, within the budget and maintaining the required quality. However, nowadays software cost estimation is a critical issue for the advance software industry. As the modern software’s behaves dynamically so estimation of the effort and cost is significantly difficult. Since last 30 years, more than 20 models are already developed to estimate the effort and cost for the betterment of software industry. Nevertheless, these algorithms cannot satisfy the modern software industry due to the dynamic behavior of the software for all kind of environments. On this study, an empirical interpolation model is developed to estimate the effort of the software projects. This model compares with the COCOMO based equations and predicts its result analyzing individually taking different cost factors. The equation consists one independent variable (KLOC) and two constants a, b which are chosen empirically taking different NASA projects historical data and the results viewed in this model are compared with COCOMO model with different values of scale factor. In this paper the author analyze more than 250 projects collected from PROMISE repository. The effort variance is very low and the proposed model has the lowest Mean Magnitude of Relative Error (MMRE) and RMSSE.
    Keywords: Lines of code, Software cost estimation, Magnitude of Relative Error, Mean Magnitude of Relative Error, Pharma Research, Early Development
  • J. Ghasemi*, J. Esmaily Pages 1494-1502
    Intrusion detection systems (IDS) by exploiting Machine learning techniques are able to diagnose attack traffics behaviors. Because of relatively large numbers of features in IDS standard benchmark dataset, like KDD CUP 99 and NSL_KDD, features selection methods play an important role. Optimization algorithms like Genetic algorithms (GA) are capable of finding near-optimum combination of the features intended for construction of the final model. This paper proposes an innovative method called chain method, for evaluation of the given test record. The main intuition of our method is to concentrate merely on one attack type at every stage. In the beginning, datasets with the proposed features by GA based on different labels will be assembled. Based on a specific sequence– which is found on different permutation of four existed labels- the test record will be entered the chain module. If the first stage –which is correlated to the input sequence-, is able to diagnose the first label, the final output has been indicated. If is not, the records will pass through the next stage until the final output be obtained. Simulations on proposed chain method, illustrate this technique is able to outperform other conventional methods especially in R2L and U2R detection with the accuracy of 98.83% and 98.88% respectively.
    Keywords: Intrusion Detection Systems, Feature Selection, Genetic Algorithms
  • R. Tang, X. Zhou*, D. Wang Pages 1503-1509
    Digital image is often degraded by many kinds of noise during the process of acquisition and transmission. To make subsequent processing more convenient, it is necessary to decrease the effect of noise. There are many kinds of noises in image, which mainly include salt and pepper noise and Gaussian noise. This paper focuses on median filters to remove the salt and pepper noise. After summarizing the main disadvantages of the conventional median filters, this paper proposes a new kind of median filter algorithm based on the detection of impulse noise points. The performance of the proposed algorithm is compared with the conventional standard median filter (SMF), extremum median filter (EMF), and adaptive median filter (AMF). Experimental results under various noise intensities show that the proposed method has better denoising performance and detail preservation compared with the other denoising methods.
    Keywords: Image Denoising, Impulse Noise Removal, Salt, Pepper Noise, Adaptive Median Filter
  • E. Hari Krishna, K. Sivnai, K. Ashoka Reddy* Pages 1517-1525
    This paper presents an empirical mode decomposition (EMD) based adaptive filter (AF) for channel estimation in OFDM system. In this method, length of channel impulse response (CIR) is first approximated using Akaike information criterion (AIC). Then, CIR is estimated using adaptive filter with EMD decomposed IMF of the received OFDM symbol. The correlation and kurtosis measures are used to select the useful IMF component from among available IMFs. Conventional AF uses random initial weight vector. The novelty of the proposed method is that it uses decimated version of one of the decomposed IMFs of received OFDM symbol as initial weight vector. This makes the proposed EMD based AF method converge to minimum mean square error (MMSE) in less number of iterations resulting in almost 50% saving of computations. The simulation studies in terms of bit error rate (BER) and mean square error (MSE) calculations established the efficacy of proposed method; and comparative studies under different modulation schemes and fading conditions revealed improved performance.
    Keywords: Orthogonal Frequency Division Multiplexing, Multi Carrier Channel Estimation, Adaptive Filtering, Empirical Mode Decomposition, Multipath Fading Channel
  • N. Javadian*, S. Modarres, A. Bozorgi Pages 1526-1537
    Due to the increasing amount of natural disasters such as earthquakes and floods and unnatural disasters such as war and terrorist attacks, Humanitarian Relief Chain (HRC) is taken into consideration of most countries. Besides, this paper aims to contribute humanitarian relief chains under uncertainty. In this paper, we address a humanitarian logistics network design problem including local distribution centers (LDCs) and multiple central warehouses (CWs) and develop a scenario-based stochastic programming (SBSP) approach. Also, the uncertainty associated with demand and supply information as well as the availability of the transportation network's routes level after an earthquake are considered by employing stochastic optimization. While the proposed model attempts to minimize the total costs of the relief chain, it implicitly minimize the maximum travel time between each pair of facility and the demand point of the items. Additionally, a data set derived from a real disaster case study in the Iran area, and to solve the proposed model a exact method called ɛ-constraint in low dimension along with some well-known evolutionary algorithms are applied. Also, to achieve good performance, the parameters of these algorithms are tuned by using Taguchi method. In addition, the proposed algorithms are compared via four multi-objective metrics and statistically method. Based on the results, it was shown that: NSGA-II shows better performances in terms of SNS and CPU time, meanwhile, for NPS and MID, MRGA has better performances. Finally, some comments for future researches are suggested.
    Keywords: Lines of Code, Uncertainty, ɛ, constraint Method, Emergency Logistics, Humanitarian Relief Chain, Evolutionary Algorithms
  • M. Azadi*, M. Iziy, A. Marbout, M. Azadi, M. H. Rizi Pages 1538-1544
    The application of Inconel 713C is very vast in different industries such as in automobiles, aircrafts, boilers and turbines. In this paper, Inconel 713C specimens were solutionized at 1000 and 1200 °C for 1 hours in order to study changes in phases and the structure of alloy to modify the γ' phase. The optical and the scanning electron microscopy were used to investigate the structure and the energy dispersive spectroscopic (EDS) and the X-ray diffraction (XRD) were applied to identify the composition and phase changes. Results showed that the solutioning heat treatment at 1000 °C for 1 hour caused to participate Cr23C6, but when the temperature of heat treatment increased to 1200°C, chromium carbides solutionized in the γ matrix. Besides, by applying the heat treatment at temperature of 1000 °C, the γ' phase dissolved in (200) and (220) plane and this phase in the plane of (111) had the best stability. However the (220) plane of γ' phase was stable thermodynamically for the specimen without the heat treatment. Phases of Ni5Al3 and Al0.42Ni0.58 were observed at the temperatures of 1000 and 1200 °C, respectively. In addition, as the heat treatment temperature increased from 1000 to 1200 °C the new phase of AlNi3C0.5 solutionized in the γ matrix.
    Keywords: Inconel 713C, Microstructure, Etchants, Solution Heat Treatment
  • S. Mahmoudkhani* Pages 1545-1554
    The transient dynamics of a beam mounted on springer-damper support and equipped with a nonlinear energy sink (NES) is investigated under the effects of shock loads. The equations of motion are derived using the Hamilton’s principle leading to four hybrid ordinary and partial differential equations and descritized using the Galerkin method. An adaptive Newmark method is employed for accurate and efficient numerical simulation and the results are used to assess the efficiency of the NES by conducting various parametric studies. The mechanisms of targeted energy transfer from the beam to the NES are indicated using the wavelet transform and Hilbert–Huang transform of the responses. Numerous modes are recognized to contribute to the response and the modes with smaller particiaption of the rigid-body motions are found to be strongly engaged in the transient resonance capture (TRC) at the initial stage of the motion. The modes with dominant rigid-body motions are, however found to be less engaed in an effective TRC. The enhanced empirical mode decomposition, with different masking signals are used to extract narrow-band intrinsic mode functions (IMFs) and simultaneous 1:1 transient resonances are observed between different IMFs of the responses especially at the initial stage of the motion.
    Keywords: Nonlinear Energy Sink, Transient Dynamics, Nonlinear Resonance Interaction, Targeted Energy Transfer, Empirical Mode Decomposition
  • A. Kumar, A. Biswas* Pages 1555-1564
    For remote places having less-strong wind, single resources based renewable energy system (RES) with battery storage can sustainably and economically generate electrical energy. There is hardly any literature on optimal sizing of such RES for very low load demand situation. The objective of this study is to techno-economically optimize the system design of a Photovoltaic (PV)-battery storage RES for an institutional academic block in Silchar, India having maximum demand less than only 30 kW. The sizing process of various subsystems of the RES is first discussed. Then the RES is techno-economically optimized under 100% reliability to power supply condition, i.e. 0% unmeet energy (UE) and least excess energy. In this, performances of three different optimization algorithms- genetic algorithm (GA) and two meta-heuristics, namely Firefly Algorithm (FA) and Grey Wolf Optimizer (GWO) algorithms are investigated and compared. The optimal configuration under least levelized cost of energy (COE) is further examined. Results demonstrate that GWO is the best optimization tool for optimizing the cost of energy (COE) in comparison with the other optimization algorithms. It has been shown that a single optimization method might not always guarantee that the objective function has converged successfully in fulfilling all the requirements of least excess energy, autonomy days, and least COE. The present research provides a useful reference for the design optimization of single resource based RES for low load demand situation.
    Keywords: Photovoltaic Renewable Energy System, Levelized Cost of Energy, Reliability, Meta, heuristic Algorithms, Cost Optimization, Load Factor, Autonomy Days
  • K. Torabi*, M. Ghassabi, M. Heidari-Rarani, D. Sharifi Pages 1565-1572
    In this paper, a relatively new method, namely variational iteration method (VIM), is developed for free vibration analysis of a Timoshenko beam with different boundary conditions. In the VIM, an appropriate Lagrange multiplier is first chosen according to order of the governing differential equation of the boundary value problem, and then an iteration process is used till the desired accuracy isachieved. Solution of VIM for natural frequencies and mode shapes of a Timoshenko beam is compared to the available exact closed-form solution and numerical results of differential quadrature method (DQM). The accuracy of VIM is approximately the same as exact solution and much better than the DQM for solving the free vibration of a Timoshenko beam. Also, convergence speed and simplicity of this method is more than the other two methods because it works with polynomial at the first iteration. Thus, VIM can be used for solving the complicate engineering problems which do not have analytical solution.
    Keywords: Variational Iteration Method, Boundary Value Problem, Free Vibration, Timoshenko Beam
  • S. T. G. Krishna Teja, C. P. Karthikeyan, M. B. Shyam Kumar* Pages 1573-1582
    The objective of this study is to design and analyse materials which are capable of harvesting water from thin air using condensation phenomenon which employs the radiative cooling approach. These passive cooling materials not only solve the water generating problems, but also employed in various cooling applications. The fundamental concept of radiative cooling is analysed and the performance parameters were identified to test the passive cooling ability of the designed material for water harvesting. The field of Photonics is studied which has the potential to obtain the surface temperature significantly lower than the atmospheric temperature by radiation phenomenon. Important parameters are identified to validate the performance of the proposed materials. ANSYS FLUENT is used to analyse the surface temperature for the given boundary conditions and the potential material which is capable of obtaining a significant temperature difference with respect to the ambient temperature is identified. A sandwich material is designed and its performance is evaluated using Computational Fluid Dynamics (CFD) by which we could achieve temperature difference of 15°C. To reduce the heat gain losses by conduction and convection, we designed a physical system which could maintain significant temperature difference even in the broad day-sunlight. CFD analysis of the designed system under similar boundary conditions gave satisfying results of maintaining the temperature difference of about 15°C for a prolonged period of time due to minimal heat gain losses. Later, two potential materials are manufactured and the performance parameters of these materials are characterized using U-V/Vis (Ultraviolet-Visible) and FTIR (Fourier Transform Infrared) Spectroscopy experiments. The results of absorption phenomenon in the U-V/Vis spectrum and the transmittance phenomenon in the FTIR spectrum of the two materials explain the reason for the passive cooling ability of materials.
    Keywords: Radiative cooling, Computational Fluid Dynamics, Photonic Material, Pigmented Foil, UV, Visible, Fourier Transform Infrared
  • N. Rajabi, R. Rafee*, S. Frazam-Alipour Pages 1583-1591
    The objective of this paper is the numerical study of the flow through an axial fan and examining the effects of blade design parameters on the performance of the fan. The axial fan is extensively used for cooling of the electronic devices and servers. Simulation of the three-dimensional incompressible turbulent flow was conducted by numerical solution of the (RANS) equations for a model. The SST- k-ω and k-ε turbulence models are applied in the simulations which are done using CFX software. The comparison between available experimental data and simulation results indicates that the SST k-ω model gives more accurate results than the k-ε model. The results also show that in separation regions and vortices, the pressure will decrease. Hub area and blade root contain large vortices. The effects of changes in the blade geometry and the number of blades on the fan performance are studied in detail. For the primary fan model with the different number of blades (4, 5, and 6), the maximum mass flow rate of 800 CFM is obtained. Hence, the number of blades had negligible effects on the maximum flow rate. By 3o% decreasing in the chord of the blades, the maximum mass flow rate of the fan with the different number of blades (5, 6 and 8) will be reduced to 500 CFM. Therefore, in order to increase the maximum mass flow rate, the chord and the width of blades should be increased. On the other hand, by increasing blades from 4 to 6 in the primary model, the maximum outlet pressure has been increased by 32%. Furthermore, it was found that in high flow rates, an increment in the number of blades had no effect on the produced static pressure.
    Keywords: Axial Fan, Numerical Simulation, Turbulent Flow, Fan Blade Design, Number of Blades
  • S. A. Rizvi*, S. P. Tewari Pages 1592-1598
    In this research work, an attempt has been made to examine the different welding parameters which affect the weldability of 304H Austenitic stainless steel (ASS) welded joint using the proper filler wire. Chemical composition of filler wire was same as that of base metal. Further this study addressed the combined effect of various welding parameters on the metallurgical and mechanical properties of the weldments. Welding was carried out at different parameters such as welding wire speed, shielding gas flow rate, welding current and arc voltage etc. Tensile tests and V-notch Charpy tests were conducted as per ASTM to determine the mechanical properties of the welded specimens. In order to determine the microstructured changes that occurred, the interface regions of the welded specimens were examined by microscope. As a result, it is reported that changing the shielding gas flow rate and wire feed speed affects the microstructure and mechanical properties of weldment. Impact tests reveal that toughness of the welded joint increases with increasing in welding current, while ultimate tensile strength (UTS) first increases and then decreases.
    Keywords: Gas Metal Arc Welding, Shielding Gas, Mechanical Properties, Morphology, Stainless Steel, Ferrite
  • A. Husain*, M. Ariz Pages 1599-1608
    The present study proposes novel micro-jet impingement heat sink with effusion holes for flow extraction. The design consists of impingement nozzles surrounded by multiple effusion holes to take away the spent fluid. A three-dimensional numerical model is used for steady, incompressible, laminar flow and conjugate heat transfer for the performance analysis of the proposed design. The computational domain is defined by applying symmetric boundary conditions around a unit cell of the jet impingements and effusion holes. The effect of several design parameters, viz., jet diameter, effusion-hole diameter, stand-off and the jet-to-effusion pitch is investigated. A higher standoff-to-jet diameter ratio exhibited lower thermal resistance whereas lower standoff-to-jet diameter ratio exhibited lower pressure-drop. Smaller jet-to-effusion hole spacing resulted in minimum temperature-rise along with maximum total pressure-drop and heat transfer coefficients.
    Keywords: Jet Impingement, Effusion Holes, Spent Flow Management, Enhance Heat Transfer, Thermal Resistance, Pressure Drop
  • R. Kumar Singh*, R. V. Sharma Pages 1609-1614
    This paper aims to predict the periodic variation of ground temperature with depth for time variant condition of ambient air temperature and solar radiation data for Jamshedpur, India. Fourier series and numerical techniques have been used to determine (hottest and coldest day) diurnal and annual temperature variation of the year 2015. The diurnal temperature variation is up to 0.2 m depth of soil whereas annual temperature variation is up to 3 m depth.
    Keywords: Soil Temperature, Numerical Techniques, Fourier Series
  • M. Dvoynikov*, V. Syzrantsev, K. Syzrantseva Pages 1615-1621
    Downhole drilling motors or mud motors are frequently used during the oil and gas well construction, especially for construction of directional and horizontal segments. However, low operation life of the down hole drilling motors and high rate of wear in their working elements may constrain their application due to technical and economical disadvantageousness. In this work, a high-torque modular motor is designed and used. Results of the theoretical and experimental investigations show that the developed down hole motor is characterized by lower torsional vibrations, improved operation stability and restored energy characteristics of the gerotor machine.
    Keywords: Drilling, Downhole Drilling Motors, Working Elements, Gerotor Mechanism of Modular Design, Torsional Vibrations