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عضویت
فهرست مطالب نویسنده:

p. kumar

  • S. Mohan *, P. Kumar
    Blended Wing Body (BWB) aircraft designs have garnered significant interest due to their potential for improved aerodynamic efficiency, particularly during critical phases of flight such as landing and take-off. This study was conducted to analyse the aerodynamic performance of BWB aircraft during ground effect interactions, which are crucial for understanding performance in these phases. Numerical simulations have been performed at a free-stream velocity of 18m/s. A moving ground velocity of 18 m/s has been imparted to avoid the formation of the boundary layer on the ground. Simulations were conducted at a Reynolds number of 85,525 based on MAC, with angles of attack ranging from -10 to 30 degrees and ground heights normalized by wingspan (h/b) between 0.2 and 1. The effect of the angle of attack and ground heights has been investigated. The investigations aim to capture the complex flow behaviour due to the varying ground proximities. The results at extremely close proximity revealed noticeable disparities in the normalised velocity and pressure distributions in the leeward location, highlighting the significant impact of the ground effect on aerodynamic performance. These findings contribute to a comprehensive understanding and analysis of BWB aircraft behaviour during ground proximity operations, providing insights for optimising proximities and improving safety and efficiency during landing and take-off.
    Keywords: Ground Effect, Pitching, Pressure Distribution, Blended Wing Body, Lift, Drag
  • K.G. Vidhya, F. Almeida, P. Kumar, B. Nagaraja *
    Nanofluids are recognized as smart fluids, offering significant advantages for enhancing heat and mass transfer. Their utility spans various domains, including electronics, biomedicine, and industrial processes. Against this backdrop, our present study focuses on examining response surface method and carrying out sensitivity analysis for Al2O3 nano-fluid flow over a stretching curved geometry. The response surface mechanism is envisioned for Eckert number, Prandtl number, as well as radiation parameter. This study introduces a novel perspective by investigating the interplay of heat and mass transfer in nano-liquids, incorporating radiative heat flux and the influence of a magnetic dipole. The Koo-Kleinstreuer and Li model analyses Brownian motion effect on viscosity and effective thermal conductivity. The modelled problem is solved using the Runge-Kutta-Fehlberg 4th–5th method. The results show that as ferrohydrodynamic interaction intensifies, it leads to an augmentation in velocity near the boundary, followed by a subsequent rise; however, the temperature profile experiences a decrease. As the thermal radiation parameter escalates, so does the temperature profile. Conversely, the concentration profile diminishes with heightened chemical reaction and Schmidt number. Entropy rises in correlation with an enhancement in the temperature ratio parameter, yet the Bejan number declines. The Pareto chart highlights 2 as the critical point for the Eckert number, Prandtl number, and radiation parameter. Specifically, the Prandtl number demonstrates a negative sensitivity across all levels of radiation parameter. Conversely, both the Eckert number and radiation parameter exhibit positive sensitivity at all levels of radiation parameter.
    Keywords: Curved Stretching Sheet, Koo-Kleinstreuer-Li Model, Magnetic Dipole, Non-Linear Radiation, Response Surface Methodology
  • بوپش کمدی، راجندرا سینگ*، ویدیا سینگ، شایلندرا سینگ، پاوان کومار، گایاتری کاشیاپ، کلدیپ دهاما
    پیشینه

    کروناویروس گاوی (BCoV) و پاتوژن های باکتریایی در کمپلکس بیماری تنفسی گاو (BRDC) در گوساله های جوان مشارکت دارند. با این حال، نقش BCoV در بروز BRDC و آسیب شناسی تنفسی مختص به مکان، در هند هنوز به خوبی بررسی نشده است.

    هدف

    این مطالعه با هدف ارزیابی شیوع BCoV در موارد BRDC انجام شد.

    روش کار

    ما 406 گوساله از شیر گرفته شده (166 راس گاو، 240 گاومیش) کمتر از یک سال، با دیسترس تنفسی و ضایعات ریوی را بررسی کردیم.

    نتایج

    موارد BRDC 98/0% بروز BCoV را نشان دادند که با تکثیر قسمتی از ژن N (172 جفت باز) از طریق RT-PCR و ایمونوهیستوشیمی تایید شد. از نظر ظاهری، 4 مورد BCoV مثبت، درجات متغیری از سفت شدن لوب های قدامی-شکمی و لوب های خلفی-پشتی کلاپس نشده، همراه با احتقان و آمفیزم را نشان دادند. از نظر میکروسکوپی، محل های ملتهب مقاطع بافتی ریه، تغییرات بارز پنومونی بینابینی را نشان داد که با نفوذ متوسط لنفوسیت ها و افزایش تعداد فیبروبلاست ها در سپتوم بین آلوئولار و استرومای مشخص گردید. مواردی که همزمان به پاستورلا مولتوسیدا آلوده بودند، لوب های قدامی-شکمی برونکوپنومونی چرکی همراه با اگزودای نوتروفیل را نشان دادند. ضایعات فوق با حضور آنتی ژن BCoV در سلول های اپیتلیال و در بقایای لومن آلوئول ها و نایژک ها/نایژه ها به خوبی لوکالیزه شدند. مقایسه توالی آمپلیکون 172 جفت باز با ژن BCoV N ارتباط نزدیکی را نشان داد.

    نتیجه گیری

    مطالعه حاضر، BCoV را به عنوان یکی از اجزای BRDC در هند نشان داد که باید در تشخیص شیوع BRDC مورد توجه قرار گیرد.

    کلید واژگان: Bcov، کمپلکس بیماری تنفسی گاو، IHC، پنومونی، RT-PCR
    B. Kamdi, R. Singh *, V. Singh, S. Singh, P. Kumar, G. Kashyap, K. Dhama
    Background

    Bovine coronavirus (BCoV) and bacterial pathogens contribute to bovine respiratory disease complex (BRDC) in young calves. However, the role of BCoV in BRDC occurrence and site-specific respiratory pathology in India remains poorly explored.

    Aims

    This study aimed to assess BCoV prevalence in BRDC cases.

    Methods

    We investigated 406 weaner calves (166 cattle, 240 buffaloes) up to ≤1 year, with respiratory distress and pulmonary lesions.

    Results

    BRDC cases exhibited 0.98% BCoV occurrence, confirmed by partial N gene amplification (172 bp) via RT-PCR and immunohistochemistry (IHC). Grossly, 4 BCoV positive cases showed variable degrees of consolidation of cranioventral lobes and non-collapsed caudodorsal lobes, associated with congestion and emphysema. Microscopically, the inflated sites of the lung tissue sections showed hallmark changes of interstitial pneumonia characterized by moderate infiltration with lymphocytes and increased numbers of fibroblasts in the interalveolar septa and the stroma of bronchioles and bronchi. In concomitant Pasteurella multocida infected cases, cranioventral lobes exhibited suppurative bronchopneumonia with neutrophilic exudate. The above lesions were well colocalized with BCoV antigen in the epithelial cells and in the debris of the lumen of the alveoli and the bronchi/bronchioles. The sequence comparison of the 172 bp amplicon with the published BCoV N gene showed close relatedness.

    Conclusion

    The present study implicated BCoV as a component of BRDC in India that should be considered in the diagnosis of BRDC outbreaks.

    Keywords: Bcov, Bovine Respiratory Disease Complex, IHC, Pneumonia, RT-PCR
  • D. Sahoo *, S. T. Kansara, P. Kumar
    Understanding how protrusions, such as fins attached to flat or streamlined bodies, affect aerodynamics, especially in high-speed contexts, is vital for aerospace applications. These protrusions significantly influence overall aerodynamics and require a comprehensive understanding for accurate analysis and prediction of aerodynamic performance. This understanding is particularly critical in supersonic flight, where even minor aerodynamic disturbances can impact vehicle stability and efficiency. Therefore, a thorough understanding of protrusion-induced flow phenomena is essential for advancing aerospace engineering and improving supersonic vehicle performance and safety. The present paper focuses on the complex supersonic flow over a vertical fin, using a combination of experimental and computational methods. The study aims to understand how variations in fin height influence the behavior of the Lambda shock and any resulting changes in shock length. Specifically, the paper investigates different fin height-to-diameter (H/D) ratios ranging from 0.5 to 1.5 in steps of 0.25. To achieve this, both experimental testing in a supersonic wind tunnel and numerical simulations using the commercial CFD tool ANSYS-FLUENT are employed. Through this dual approach, the paper seeks insights into the characteristics of the Lambda shock and its effects on key aerodynamic parameters, such as shock strength and drag coefficient. By thoroughly investigating these aspects, the paper contributes to a deeper understanding of the complex flow phenomena associated with supersonic flow over vertical fins, potentially guiding the design and optimization of aerospace vehicles. The outcomes indicate that a fin height of 12 mm (H/D=1.0) provides the best balance in terms of pressure distribution, Lambda shock length, and drag coefficient, making it the optimal choice for enhancing aerodynamic stability and performance in supersonic conditions.
    Keywords: Protrusions, Vertical Fin, Aerodynamics, Experimental Testing, Supersonic Flow, Aerospace Applications, Flow-Phenomena
  • P. Kumar, D. Deka *, A. Yadav, Ashwani ., M. Kumar, J.P. Das, A. Singh, A. Gurjar
    BACKGROUND AND OBJECTIVES
    Evapotranspiration is an important component of water balance associated with the hydrological cycle and biological processes. Accurately estimating the rate of evapotranspiration is crucial for understanding fluctuations in water availability and effectively managing water resources in a sustainable manner. The study aims to examine the correlation between actual evapotranspiration and potential evapotranspiration by assessing the linkages with vegetation and snow cover in an ecologically fragile located in the northwestern Himalaya.
    MATERIALS AND METHODS
    The present study uses remote sensing Landsat satellite data series to map vegetation cover and snow cover in the area. Remote sensing data accessed from Moderate Resolution Imaging Radiometer evapotranspiration project data was used for calculating evapotranspiration and potential evaporation. The data from the Climatic Research Unit (2000–2022) was additionally utilized for the computation of potential evapotranspiration. The study investigates variances in evapotranspiration and explores correlations between normalized difference vegetation index and normalized difference snow index. It further examines the correlation between potential evapotranspiration and actual evapotranspiration.
    FINDINGS
    The study conducted from 1991 to 2021 demonstrates a notable rise in vegetation cover by 20.18 percent, showcasing spatial variations across the region. Conversely, there has been a significant decline in the extent of snow cover throughout this period. A positive correlation was identified between vegetation cover and evapotranspiration, whereas a negative correlation was observed between snow cover and evapotranspiration. Actual evapotranspiration is on the rise while potential evapotranspiration is declining throughout the region.
    CONCLUSION
    Hydrological cycle of a region is governed by many factors such as climate (precipitation, temperature), geohydrology, land use and land cover, socio-economic condition of habitants and institutions. Vegetation cover, snow cover, actual evapotranspiration and potential evapotranspiration and their relationship indicates changes in local and regional climate. An incremental rise in plant growth across the study site, coupled with spatial variability and a reduction in snow cover in the elevated mountainous zone, is influencing both actual evapotranspiration and potential evapotranspiration. Increase in actual evapotranspiration in the High Himalayan area of Himachal Pradesh attribute to substantial increase in vegetation cover in the dry cold desert region. The findings of the study will contribute to the comprehension of essential elements of water cycles and water budgets, facilitating improved resource allocation for climate-resilient sustainable initiatives.
    Keywords: Actual evapotranspiration, Climate change, Correlation, Potential evapotranspiration, Snow Index, Vegetation index
  • P. Kumar, S. Das *
    Buzz is an unwanted and inevitable phenomenon occurring due to the subcritical operation of intake which needs a comprehensive understanding. The buzz pattern in axisymmetric intakes differs from 2D counterpart and requires further investigation. The current study emphasizes the ways of buzz formation and its sustenance at supersonic speeds. In the present study URANS simulations have been done for various throttling ratios to simulate the engine demand conditions. It has been found that the onset of intake buzz happens for anything above the throttling ratio of 0.54. An active flow control technique using plasma actuator was used here to mitigate the influence of buzz. The study also emphases on the impact of plasma power densities on the intake performance.
    Keywords: Buzz, Throttling, Plasma Actuator, Flow Control, Supersonic Intake, Axisymmetric
  • B. Nagaraja, B. J. Gireesha, F. Almeida, P. Kumar *, A.R. Ajaykumar
    Darcy-Forchheimer model has been used to consider the mathematical and statistical aspects of Prandtl nanofluid flow on a stretched curvy geometry, with homogenic-heterogenic reactions, nonlinear radiation, exponential heat, Joule heating, velocity slip, and convective heat conditions. An account of entropy significance has been given to boost the applicability of the study. The 4-5th ordered numerical tool, Runge-Kutta-Fehlberg, has been employed to establish the plots for the considered flow. ANOVA and Taguchi optimisation technique is used to obtain the optimal condition in enhancing the heat transfer rate for modelled mathematical problem. Here, the study reveals that the increasing homo-heterogenic strength parameters foster the concentration profile. The study also found that the thermal curves are positively affected by the radiation parameter and the temperature differential parameter. In addition to this, graphical portraits of isotherms and streamlines have been given to characterise the flow and heat pattern. Taguchi method reveal that first level of Prandtl number, magnetic parameter, Weissenberg number, heat source parameter and third level of curvature parameter, produce maximum Nusselt number. Heat source parameter has large contribution of about 49.45% among the other parameters and Prandtl number has the least contribution of about 1.4% for optimisation.
    Keywords: Statistical interpretation, Homogeneous-heterogeneous reactions, Slip flow, convection, non-Newtonian nanofluid
  • شوتا والچا، هیتشوار سینگ یاداو، نارایاناسوامی روپا، سیجپالایا دودایا وینای کومار، مونیکا بهاردواج، ویدیا سینگ، پاوان کومار*

    پیشینه: 

    مدی-ویسنا (MV) یک بیماری لنتی ویروسی نشخوارکننده کوچک (SRLV) است که گوسفند و بز را تحت تاثیر قرار می دهد و باعث تغییرات پاتولوژیک در اندام های مختلف از جمله ریه ها، غدد لنفاوی ریوی، غدد پستانی، مفاصل و سیستم عصبی مرکزی می شود.

    هدف

    مطالعه حاضر به منظور شناسایی اسید نوکلئیک ویروس مدی-ویسنا (MVV) و آنتی ژن p28 MVV در اندام های مختلف گوسفند و بز مبتلا شده انجام شد.

    روش کار

    در مجموع 657 نمونه (169 خون، 136 ریه، 96 غدد لنفاوی ریوی، 74 مغز، 54 غده پستانی، 78 مفاصل، و 50 طحال) از نظر وجود اسید نوکلئیک MVV با استفاده از روش Nested PCR غربالگری شدند. نمونه های سرم از نظر آنتی بادی SRLV توسط ceLISA غربالگری شدند. ایمونولوژی MVV با استفاده از آنتی بادی پلی کلونال علیه آنتی ژن p28 توسط ایمونوهیستوشیمی در ریه ها، غدد لنفاوی، غدد پستانی و بافت های مفصلی نشان داده شد.

    نتایج

    از 657 نمونه، 7/10% (657/70) نمونه برای MVV مثبت بودند. در بین اندام های مختلف، ریه ها (7/25%) بالاترین میزان آلودگی را نشان دادند و سپس غدد پستانی (8/14%)، خون (5/9%)، بافت های مفصلی (7/7%)، مغز (4/5%)، و غدد لنفاوی ریوی (1%) قرار گرفتند. آنتی بادی SRLV در 2/29% از نمونه های سرم گوسفند و بز توسط cELISA شناسایی شد. تجمع پروتئینP28 MVV در ریه ها، غدد لنفاوی، غدد پستانی و بافت های مفصلی مشاهده شد. با این حال، نشانه مثبت آنتی ژن P28 MVV در بافت های مغزی یافت نشد.

    نتیجه گیری

    بالاترین میزان مثبت MVV در بافت های ریه نشان دهنده تمایل بیشتر ویروس در بافت ریوی است.

    کلید واژگان: ایمونوهیستوشیمی، مدی-ویسنا، شیوع سرمی، نشخوارکنندگان کوچک
    Sh. Valecha, H. S. Yadav, N. Roopa, S. D. Vinaykumar, M. Bhardwaj, V. Singh, P. Kumar *
    Background

    Maedi-visna (MV) is a small ruminant lentiviral (SRLV) disease affecting sheep and goats, and causes pathological alterations in various organs including lungs, pulmonary lymph nodes, mammary glands, joints, and CNS.

    Aims

    Present study was focused to detect the MV virus (MVV) nucleic acid and MVV p28 antigen in different organs of the spontaneously MVV affected sheep and goats.

    Methods

    Total of 657 samples were collected from sheep and goats (169 blood, 136 lungs, 96 pulmonary lymph nodes, 74 brain, 54 mammary gland, 78 joints, and 50 spleen) and screened for MVV nucleic acid using nested PCR assay. Serum samples were screened for SRLV antibodies by cELISA. Immunolocalization of MVV was demonstrated by using the polyclonal antibody against p28 antigen by immunohistochemistry in lungs, lymph nodes, mammary glands, and joint tissues.

    Results

    Out of 657 samples, 10.7% (70) were found positive for MVV. Among different organs, lungs showed highest positivity (25.7%) followed by mammary glands (14.8%), blood (9.5%), joint tissues (7.7%), brain (5.4%), and pulmonary lymph node (1.0%). SRLV antibodies were detected in 29.2% of the serum samples of both sheep and goats by cELISA. MVV p28 antigen immunostaining was observed in lungs, lymph nodes, mammary glands, and joint tissues. However, the presence of MVV p28 antigen could not be demonstrated in the brain tissues.

    Conclusion

    The highest positivity of MVV in lung tissues indicated higher predilection of the virus in the pulmonary tissue.

    Keywords: Immunohistochemistry, Maedi-Visna, Seroprevalence, Small Ruminants
  • آنارا تودی فاسلو رحمان، مگا شارما، آسوک کومار ماریاپان، سیجپالی دودایاه وینی کومار، دیواکار سینگ رانا، دیپاک کومار پانکاج، نیراج کومار، پراسانت موهان نایر، پیچاندی تامیژان، گوتولا سایکومار، ویدیا سینگ، پاوان کومار*

    پیشینه: 

    استئودیستروفی فیبروزا (ODF) یک اختلال متابولیک است که بر سیستم اسکلتی تاثیر می گذارد و باعث از بین رفتن پیش رونده توده استخوانی کلسیفیه و جایگزینی آن با بافت فیبروزه می شود که ممکن است به دنبال هیپرپاراتیروئیدیسم اولیه یا ثانویه رخ داده باشد. هدف این گزارش مستندسازی یافته های بالینی آسیب شناسی ODF در یک گله بز جوان است که عمدتا با رژیم غذایی غنی از سبوس گندم تغذیه می شدند.

    توصیف بیمار: 

    در یک گله متشکل از 50 بز 1 تا 2 ساله پرواری، 7 بز با بزرگ شدن دو طرفه صورت به صورت بالینی که منجر به تنگی نفس و دشواری در گرفتن و جویدن غذا شده بود، ارجاع داده شدند. از بین 7 بز مبتلا به بیماری، 4 بز در مدت 2 ماه مردند.

    یافته ها/درمان و نتیجه درمان: 

    معاینه بالینی، بزرگی دو طرفه فک پایین و بدشکلی اندام حرکتی را نشان داد. در رادیوگرافی، رادیوپاسیته فک بالا و فک پایین کاهش یافته بود. سیتولوژی آسپیراسیون با سوزن ظریف (FNAC) از استخوان های آسیب دیده، خوشه هایی از فیبروبلاست ها و استئوکلاست های تکی را نشان داد. در کالبدگشایی، فک پایین یک قوام گوشتی را نشان داد. بخش های بافت شناختی فک پایین نشان دهنده استئوپنی شدید، استئوکلاست های متعدد، لاکون هاوشیپ و فیبروپلازی وسیع بود. اقدامات اصلاحی رژیم غذایی منجر به جلوگیری از ODF در بقیه گله شد.

    نتیجه گیری

    تغذیه بیش از حد سبوس گندم در بزهای پرواری ممکن است منجر به عدم تعادل کلسیم و فسفر و در نتیجه هیپرپاراتیروئیدیسم ثانویه تغذیه ای و بدشکلی های اسکلتی متعاقب آن شود. FNAC استخوان های آسیب دیده، یافته های ماکروسکوپیک و بافت شناسی، تشخیص بالینی آسیب شناسی ODF را امکان پذیر می کند.

    کلید واژگان: بز، استئودیستروفی فیبروزا، هیپرپاراتیروئیدیسم ثانویه
    A. T. Faslu Rahman, M. Sharma, A. K. Mariappan, S. D. Vinay Kumar, D. S. Rana, D. K. Pankaj, N. Kumar, P. M. Nair, P. Thamizhan, G. Saikumar, V. Singh, P. Kumar *
    Background

    Osteodystrophia fibrosa (ODF) is a metabolic disorder affecting the skeletal system, causing progressive loss of calcified bone mass and its replacement with fibrous tissue, which may be a sequel to primary or secondary hyperparathyroidism. This report intends to document the clinicopathological findings of ODF in a flock of young goats fed primarily on a wheat bran-rich diet.

    Case description: 

    In a flock of 50 stall-fed goats aged 1 to 2 years, seven were clinically presented with bilateral facial enlargement, leading to dyspnea and difficulty in prehension and mastication. Among the seven clinically affected goats, four died in 2 months.

    Findings/treatment and outcome: 

    The clinical examination revealed bilateral mandibular enlargement and limb deformities. On radiography, the maxilla and mandible had decreased radiopacity. Fine needle aspiration cytology (FNAC) from the affected bones showed occasional fibroblasts and individual osteoclasts clusters. On necropsy, the enlarged mandible revealed a meaty consistency. Undecalcified histological sections of the mandible showed severe osteopenia, multiple osteoclasts, Howship’s lacunae, and extensive fibroplasia. Dietary corrective measures led to the prevention of ODF in the rest of the flock.

    Conclusion

    Excessive wheat bran feeding in stallfed goats might have led to calcium and phosphorus imbalance, resulting in nutritional secondary hyperparathyroidism and subsequent skeletal deformities. FNAC of the affected bones, gross and histological findings provide a clinicopathological diagnosis of ODF.

    Keywords: Goat, Osteodystrophia fibrosa, Secondary hyperparathyroidism
  • A. Arora, S. Das, P. Kumar *
    With the advancement in the modern transport system, it has become imperative to achieve larger aircraft volume at minimum cost wherein aerodynamics plays a major role. The present work aims to investigate the flow over a typical blended wing body (BWB) configuration at different angles of attack adopting experimental and computational techniques. Experiments consisted of the force measurements and oil flow visualizations at a free stream velocity of around 19 m/s. Computations were made using the commercially available software ANSYS 18.1. Results indicated that the use of a Blended Wing Body Configuration resulted in improved aerodynamic characteristics in comparison to other wing configurations such as Delta/ Double delta wings. Surface flow visualization carried out over the BWB configuration indicated the reason behind increased lift coefficients. Reasonable agreement of experiments and computations was observed.
    Keywords: Blended wing body, Oil flow, Experiment, UAV
  • Kanna Suneetha, Shaik Ibrahim *, G.V. Reddy, P. Kumar

    Due to their position in various industrial applications, convective fluid flow structure is intricate and enticing to investigate. Here the flow has been made by considering multitudinous apropos parameters like induced magnetic factor, heat source and viscous dissipation effects for the mixed convective chemically radiative fluid from a vertical surface. The frame work of mathematical pattern is conferred with in the circumstances of a system of ordinary differential equations under felicitous legislation.The governed mathematical statement is handled analytically by perturbation strategy. Diagrams and numerical values of the profiles are delineated with apropos parameters. Our sketches illustrate that the induced magnetic field is perceived to be downward with intensification in magnetic parameter. Temperature profile is accelerated by rising thermal radiation and concentration distribution is decelerated by enhancing the chemical reaction and Schmidt number.

    Keywords: mixed convection, heat, mass transfer, Heat generation, induced magnetic field, Chemical reaction, Radiation
  • Shaik Ibrahim *, K Suneetha, P Kumar, Kanithi Jyothsna

    Due to the presence of rheological flow parameters and viscoelastic properties, non-Newtonian fluid structure is intricate and enticing to investigate. The flow has been made by considering variable temperature and radiation effects for the magnetohydrodynamic viscoelastic liquid past a moving vertical plate in a porous state. First order homogeneous chemical reaction, Soret number, variable temperature and concentration have been taken into account. The leading mathematical proclamation is handled analytically by perturbation strategy. The central aspiration of this work is to explore the consequences of sundry parameters on fluid flow, thermal boundary and concentration profiles. Diagram and tabular trends of the profiles are delineated with apropos parameters. Our sketches illustrate that the velocity profile exposes   decelerate scenery with escalating M due to the Lorentz force in the opposite direction of flow. Temperature profile is getting accelerated owing to thermal radiation and concentration distribution is declined by boosting up the chemical reaction and Schmidt number. Diminishing nature of momentum boundary layer with Sc is also portrayed. Furthermore, at the end of this paper the effects of different parameters on skin fricition coefficient and local Nusselt number are investigated.

    Keywords: Visco-elastic, MHD, Porous media, Heat sink, Radiation, Chemical reaction, Soret Number
  • P. Kumar *, M. Gupta, V. Kumar
    With the increased diversity of the customer demand and complexity of the product, Inconel 825 is widely used to meet the actual needs, especially in the aerospace industry. It is difficult-to-cut material because of its high toughness and hardness. The present research attempts to optimize the process parameters of wire electric discharge machining during the cutting operation of Inconel 825. The wire electric discharge machining characteristics such as pulse-on time, pulse-off time, spark gap voltage, peak current, wire tension, wire feed are taken into consideration. The performance was measured in terms of material removal rate, surface roughness, and wire wear ratio. The central composite design of response surface methodology at an α value of ± 2 was employed to establish the mathematical model between process parameters and performance measures. A multi-objective particle swarm optimization algorithm has been used to find the optimal solutions called Pareto optimal solutions. It uses the concept of dominance to find the non dominated set in the entire population and the crowding distance approach to finding the best Pareto optimal solutions with a good diversity of objectives. The confirmation experiments of the multi-objective particle swarm optimization algorithm show a significant improvement in material removal rate (27.934 to 31.687 mm2/min), surface roughness (2.689 to 2.448μm), and wire wear ratio (0.027 to 0.030). SEM micrograph studies showed the number of cracks, pockmarks, craters, and pulled out material on the workpiece and wire electrode surface. Energy Dispersive X-ray analysis is performed to investigate the presence of elements on the work surface other than the base material.
    Keywords: WEDM, Inconel 825, surface roughness, Wire wear ratio, RSM, MOPSO algorithm
  • A Sachdeva*, D Kumar, P Kumar

    The paper presents a multi-factor decision-making approach for prioritizing failure modes as an alternative to traditional approach of failure mode and effect analysis (FMEA). The approach is based on the ‘technique for order preference by similarity to ideal solution’ (TOPSIS). The priority ranking is formulated on the basis of six parameters (failure occurrence, non-detection, maintainability, spare parts, economic safety and eco-nomic cost). The Shannon`s entropy concept has been used for assigning objective weights to maintenance pa-rameters. The application of the approach has been reported with an actual case from a paper industry to illus-trate the use of the proposed methodology.

    Keywords: Maintenance, TOPSIS, Decision support system, FMECA, MCDM
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