bluuebunny/crossref_metadata_2025 huggingface dataset:
تقويم أداء مدرسي اللغة العربية في المرحلة المتوسطة في ضوء مهارات التعلم الذاتي
Authors: د.ريما الاحدب  , يونس شافي علوان
Published: December 2023

تم استخدام المنهج الوصفي التحليلي في هذا البحث لدراسة درجة انخراط معلمي اللغة العربية في المرحلة المتوسط في مهارات التعلم الذاتي.
وشكلت العينة ثلاثة وتسعون معلم لغة عربية للمرحلة المتوسطة من مدارس محافظة واسط بمنطقة العزيزية. تم اختيار هؤلاء المدربين بشكل عشوائي من بين مجموعة معلمي اللغة العربية في العينة.
يتم تتبع مقدار تقنيات التعلم الذاتي التي يستخدمها مدرسو اللغة العربية من خلال استبيان.
أظهرت النتائج أن مدرسي اللغة العربية يستخدمون تقنيات التعلم الذاتي بمعدل متوسط، ويتخذون خطوات مثل إنشاء جداول زمنية مناسبة للأهداف التعليمية ومستويات الطلاب بالإضافة إلى تقنيات التعلم الذاتي.
وبحسب عوامل الجنس ودرجة التعليم وسنوات الخبرة، تشير النتائج إلى عدم وجود فروق بين ممارسات التعلم الذاتي للمعلمين والمعلمات في موضوع اللغة العربية.
قدم البحث العديد من الاقتراحات والأفكار من خلال النتائج.
نموذج مقترح لتفعيل المراجعة الخارجية في النظام المحاسبي المالي و السياسة الإقتصادية بالصومال.
Authors: د. سعيد حسن إسماعيل جامع.
Published: December 2023

تناولت الدراسة نموذج مقترح لتفعيل المراجعة الخارجية في النظام المحاسبي المالي و السياسة الإقتصادية بالصومال . حيث تمثلت مشكلة الدراسة في السؤال الرئيسي التالي : هل ممكن اقتراح نموذج لتفعيل المراجعة الخارجية لتحقيق جودة مخرجات النظام المحاسبي و الموثوقية النظام المالي بما يكفل جودة المعلومات المالية كمدخلات لسياسة الاقتصادية . هدفت الدراسة الى اقتراح نموذج لتفعيل المراجعة الخارجية يمكن معه التأكيد على ايجابيتها على النظام المالي دون الاضرار بالسياسات الاقتصادية الصومالية . توصلت الدراسة الى النتائج منها : تفعيل ممارسة المراجعة الخارجية على السياسة الاقتصادية ضرورة لضبط الاداء المالي والانفاق القومي والرقابة عليه بشكل جيد . أوصت الدراسة بتوجيه الفكر المحاسبي لإجراء مزيد من الدراسات التي من شأنها تقديم تفسيرات إضافية بشان أثر تفعيل المراجعة الخارجية على كل من النظام المحاسبي المالي وكفاءة السياسة الاقتصادية في الصومال .
تأثير الأسلوب التعاوني في تحسين مهارة الطبطبة بكرة السلة لدى متعلمي الصف الثاني متوسط
Authors: د. محمود العتر  , مصطفى عدنان
Published: December 2023

يتلخص هدف الدراسة بالتعرّف إلى أثر الأسلوب التعاوني في تحسين مهارة الطبطبة في كرة السلة لدى متعلمي السنة الثانية من المرحلة المتوسطة في متوسطة الوسيلة للصبيان في ديالى. ولهذا الغرض تم الارتكازُ على التجريب في فرقتين إحداهما للتجريب والأخرى مضبوطة، فقد تألفت الأولى من 33 طالبا من الصف المبحوث وقد تلقوا التدريس وفق خطة تقوم على الأسلوب التعاوني لتحسين مهارة الطبطبة بينما ضمت الثانية العدد  نفسه في ذات المستوى ليتلقوا التدريس تقليديّا وفق النمط المعتاد والسائد. وفي النتائج فقد توصلت الدراسة إلى أن للأسلوب التعاوني أثرًا يتخذ منىىً إيجابيًا يتّضحُ في تنمية وتحسين المهارة المبحوث عندَ التجريبيين، كما نالَ أعضاؤها علاماتٍ أعلى من تلك التي نالها الأعضاء المضبوطين في اختبار كشف التحصيل المكتسب العملي الذي أُجريَ بعد التطبيق، بالإضافة إلى التنمية الحاصلة في المهارة المبحوثة لدى الأفراد التجريبيين، كما أشارت النتائج في ازدياد اللعب الجماعي والتعاوني بين المتعلمين أثناء تأديتهم مهارة الطبطبة والتمرير، وقد أكدت أيضًا على تطور الأداء الرياضي لديهم في كرة السلة نتيجة إتقانهم المهارة. ومن جراء ما تم التوصل إليه من محصلات  خرجت الدراسة بمجموعة من التوصيات بالاهتمام باعتمادِ الأسلوب المتَّبَعِ في التجريب وهو التعاوني من أجل تنمية المهارة المرجوة ، والتوسع في استخدام الأسلوب التعاوني على مراحل دراسية أخرى ومهارات أخرى ، ومعرفة مدى تأثير هذا الأسلوب في تعليم مهارات أخرى في كرة السلة.
Applying Decision Tree and Bibliometric Analysis: The Analysis of Digital Governance Determinants
Authors: Kunviroteluck Benjawan , Kongthon Alisa , SaeLim Patipan
Published: December 2023

Digital governance plays a crucial role in leading organizations in their digital transformation process. This paper aims to explore the analysis of digital governance determinants through the application of decision tree and bibliometric analysis techniques. Understanding these factors can help organizations in developing effective digital governance initiatives and strategies. Bibliometric analysis is utilized to identify new trends and overall research landscape of digital governance. K-means clustering and decision tree are then used to identify key determinants of effective digital governance. Our results show that leadership is the most initial important factor. In addition, to enhance digital governance to the highest level, organizational culture that is driven from the leader is also another important factor. The findings of this study yield insights for practitioners and managers who seek to improve their digital governance practices.
Enterprise data and semantic modelling: conceptual model of information technology incident management
Authors: Arnaoudova Kristina , Nisheva-Pavlova Maria
Published: December 2023

Knowledge management methods and their efficient implementation across the organization determine sound and resilient management of processes. This paper studies the semantic integration of enterprise data sources essential to service management processes. Implementing a semantic layer within the enterprise architecture uses various tools, methods, and techniques. The semantic conceptual model unifies and implements intelligent integration of multiple data sources across the enterprise, achieving consistency and more accessible interpretation. Specifically, we draw our attention to incident and problem management within enterprises. We propose an ontology - a conceptual model for the incident management process. The incident ontology presented as an intelligent data integration layer component aims to achieve operational excellence. Besides, this ontology is a fundamental part of the proactive process in problem management. An ontology as a logic-based system supports integrity validation. It infers new, no explicitly modeled facts in the problem domain, thus helping experts better analyze and understand the problem. We discuss the conducted experiment results with the proposed in this article conceptual model using the enterprise knowledge graph platform. It can be perceived as a framework for a query-answering system with components, including ontology schema, data mapping, and classification methods for data graph enrichment.
Marsupiais em três vertentes da Chapada das Perdizes, ecotone Cerrado - Mata Atlântica no sul do Estado de Minas Gerais
Authors: Pecora Henri Barbosa , Moura Aloysio Souza de , Machado Felipe Santana , Alvarenga Guilherme , Lacerda Leone , Gregorin Renato
Published: December 2023

No sul de Minas Gerais há uma grande diversidade de habitats que determinam uma notável alternância de espécies entre diferentes fitofisionomias. A conservação dessas áreas é pertinente para a preservação da fauna associada, principalmente para o grupo dos marsupiais que demonstra potencial para bioindicação e restauração ambiental. O estudo em questão analisou três vertentes na Chapada das Perdizes com diferentes características climáticas e vegetacionais com o objetivo de apresentar uma lista preliminar da composição da comunidade de marsupiais ocorrentes no sul do estado de Minas Gerais.
Crescimento inicial da leucena inoculada com fungo micorrízico arbuscular sob diferentes lâminas de irrigação
Authors: Fonsêca Jônathas Mendes , Carneiro Romero Francisco Vieira , Ferreira José Orlando Piauilino , Matos Filho Carlos Humberto Aires , Cardozo Júnior Francisco Marques
Published: December 2023

Avaliou-se o crescimento inicial da leucena quando as mudas foram inoculadas com fungo micorrízico arbuscular (FMA) e, em seguida, cultivadas a campo sob lâminas de irrigação. Avaliaram-se a taxa de crescimento relativo, altura e diâmetro do caule, massa fresca e seca da parte aérea, teor de clorofila, colonização micorrízica e número de glomerosporos. Utilizou-se o delineamento inteiramente casualizado (DIC) com três repetições, em fatorial 4x4: quatro lâminas de irrigação (25%; 50%; 75% e 100% da ETo), quatro condições microbiológicas do substrato da muda (substrato autoclavado inoculado com o FMA- Glomus clarum (AI); autoclavado não inoculado (ANI); em condição natural inoculado com o FMA- Glomus clarum (NI) e em condição natural não inoculado (NNI)). Altura e diâmetro do caule variaram dependendo da inoculação com FMA no substrato. Em substrato contendo apenas solo natural, a inoculação com Glomus clarum é tecnicamente viável para promover maior crescimento das plantas até 105 dias.
Analysis of The Feasibility of Revitalization of The Type a Amplacing Terminal and The Performance of The Sisingamangaraja Road Section, Medan
Authors: Dodi Frenky  , Sinar Indra Kesuma  , Satia Negara Lubis
Published: December 2023

The main objective of this research is to analyze and find out if the investment plan is profitable in the future so that it is feasible or not to be implemented. Apart from that, this research also aims to analyze the Operational Performance of the Sisingamngaraja Road Section which includes: Side Obstacles, Free Flow Speed, Travel Speed and Time, and Service Level. The data used in this research are primary data and secondary data. Primary data was obtained through interviews and observations. Meanwhile, secondary data was obtained from related agencies or services such as the Medan City Transportation Department.  The analytical method used in this research uses two analytical tools, namely investment feasibility analysis and road segment performance analysis. The research results obtained from the Net Present Value for the next 10 years are IDR. 60,400,000. shows that it is feasible to revitalize the Amplas Type A Terminal. This can be proven from the investment acceptance criteria and the NPV method, namely if the calculation results show that the value is positive then the investment is worth implementing. From the calculation results, the IRR of 30.5% shows that the interest rate will equal the present value of the investment. With present value, the value of net cash receipts in the future. As a criterion for acceptance of this method, if the calculated interest rate is greater than the desired interest rate, the investment is accepted. In this case the interest rate is 20%, so the IRR of 30.5% is said to be feasible for the revitalization of the Amplas Type A Terminal. The Profitability Index (PI) is 1.10 (accepted) because PI > 1. From the results of the Payback Period calculation, the Payback period for the revitalization of the Amplas Type A Terminal is 22.2 years. This means it is shorter than the economic investment period, namely 35 years, so the Payback Period criteria for the revitalization of the Amplas Type A Terminal can be accepted because it is lower than the useful life period. The performance of the section on Jalan Sisingamngaraja by determining the size of the road capacity and traffic volume is known to still have problems with congestion during peak activity hours.
Diabetes Attitude and Self-Efficiency Levels of Patients with Type 2 Diabetes Mellitus Taking Insulin
Authors: GÜN Nurgül , TÜLÜCE Derya
Published: December 2023

This study was conducted with descriptive design to determine the disease attitudes and self-efficacy levels of patients with type 2 diabetes mellitus taking insulin. The study was conducted with 120 patients diagnosed with type 2 diabetes mellitus, who applied to the internal medicine outpatient clinics of Balıklıgöl State Hospital between January and April 2021. Personal information form, Diabetes Attitude Scale, and Self-Efficacy in Type 2 Diabetes scale were used to collect data. The data were analyzed in the Statistical Package of Social Sciences 25.0 software. The total mean score of the patients was found to be 57.25±19.07 for the self-efficacy in type 2 diabetes scale. In the study, it was determined that there was a strong positive correlation between diabetes attitude scale and diabetes self-efficacy scale (p
The Link between Market Orientation and Customer Satisfaction in the Tourism Industry: A Situational Analysis of Sub-Saharan Africa
Authors: Jaensson Jan-Erik Jaensson , Uiso Hawa Uiso
Published: December 2023

This literature study provides a review of research in the fields of market orientation and customer satisfaction in the tourism industry. The objective of this research is to assess the link between market orientation, customer satisfaction and tourism business development in SubSaharan Africa. This link has not been studied in this region before and this research gives a situational analysis of the conducted research. The assumption supported in the literature is that market orientation promotes business performance, and ultimately improves customer satisfaction and loyalty to the products/services offered by the organization. Both market orientation and customer satisfaction are supposed to create value for customers. However, there are few studies of this kind in Africa and very few, in Sub-Saharan Africa. Studies linking market orientation to customer satisfaction are mainly in the form of consultancy reports and a few are academic in nature. The focus on tourism industry is due to its importance for the region. The tourism industry is fast growing, internationally competitive, generates foreign currency and creates employment. The findings are that no research has been conducted in the tourism industry in Sub-Saharan Africa linking market orientation to customer satisfaction.
Succession Planning and the Sustainability of Transport Enterprises: A Study of Transport Business in Njombe and Iringa Regions
Authors: Tonya Emmanuel Mgaya
Published: December 2023

The main objective of this study was to explore succession planning and the sustainability of transport enterprises. The study was done in Njombe and Iringa regions. The study population was 240 individuals or family transporters; the sample size was 70 respondents. Stratified sampling techniques were used and a proportional distribution was done to select the respondents from the Njombe, Mufindi and Iringa urban. From the proportional distribution 18 respondents, 6 respondents and 46 respondents were picked from Njombe, Mufindi and Iringa districts respectively. The study based on trait and behavioural theories of leadership management. Qualitative content analysis was used for logical determining the relationship between strategic succession planning and business sustainability. Findings from this study revealed the casual factors influencing the higher failure rate of transport business and its sustainability includes lack of strategic succession planning particularly in the case of the first generation retirement from transport business. The study, observed that owners of business do not prepare successors in advance, this poses problems to business sustainability in Tanzania. The main contribution of knowledge is the issue of strategic succession planning as a factor to enhanced business sustainability, transport included.Â  The study has recognized that, transport business is used as a venture for capital formation to other economic activities like housing, estate and hospitality. However, a guideline for systematic succession planning has been proposed to be used by transporters for sustainability.
Simulation of Drag Crisis in Flow Past a Circular Cylinder using 2D Computations
Authors: Singh S.P. , Mittal S.
Published: December 2023

The unsteady incompressible 2D Navier-Stokes equations are solved using a finite element method with Streamline-Upwind/Petrov-Galerkin (SUPG) and Pressure-Stabilizing/Petrov- Galerkin (PSPG) stabilization terms for high Reynolds number (105 to I06) flow past a cylinder to stimulate drag-crisis. The mean drag coefficient for various Re are compared with experimental data. It is observed that the low at Re =106 separates much later, from the cylinder surface as compared to that at Re =105. The wake at Re =106 is narrower than that at Re = 105. The time-averaged flow field shows a standing bubble just downstream of the flow separation point for the Re = 105 flow. The bubble is not observed for the flow at Re = 106. The energy spectrum of the flow exhibits the characteristics of 2D isotropic turbulence.
Fracture Behaviour of Carbon Steel Straight Pipe with Through-Wall Crack under Cyclic Loading
Authors: Venu Kumar D. , Seetharaman S. , Pukazhendhi D.M. , Murthy D. S. Ramachandra , Gupta Suneel K. , Bhasin Vivek , Vaze K. K. , Kushwaha B. S.
Published: December 2023

Carbon steel straight pipes form part of the primary heat transport system of nuclear power plants. They may be subjected to dynamic-cyclic loads during earthquake event. This dynamic cyclic loading significantly affects the fracture resistance and the load carrying capacity of cracked components. Further, for the application of leak-before-break concepts, experimental investigations are essential. Therefore, the aim of the present study is to investigate the effect of cyclic loading on fracture resistance of through-wall cracked straight pipes. The paper presents details of the cyclic fracture test on a straight pipe and the results thereof. The behaviour of the pipe was compared with the fracture behaviour under monotonic loading. The study has shown that the load capacity of the pipe is reduced under cyclic loading and the failure is by cyclic tearing followed by sudden collapse.
A Simple Energy Method to Predict the Thermal Post Buckling Behaviour of Columns
Authors: Rao G. Venkateswara
Published: December 2023

No Abstract
Evaluation of Impact Induced Damage in Woven Fabric CFRP Laminates
Authors: Bhat M.R. , Murthy C.R.L.
Published: December 2023

The residual strength of an impacted composite laminate depends upon the extent and distribution of the damage through the thickness. This in turn is determined by the energy and velocity of impact, and other material and test parameters. In-plane compressive loading of the multi-layered composite laminates containing damage is considered to be highly critical since under such a condition the strength reduction is expected to be the largest. Hence, much of the effort in recent research has been directed towards understanding the behavior of impact-damaged laminates under compressive loading. One type of test that has been widely used to evaluate the residual mechanical properties of these laminates is the compression after impact (CAI). In this study, compression tests have been conducted as per NASA specifications on woven fabric Carbon Fiber Reinforced Plastic (CFRP) laminate specimens unimpacted and impacted at different energy levels. Strain gauges have been employed to ensure uniform, symmetric loading and to obtain the failure strain. In this paper, the test procedure foLlowed and the results obtained from CFRP laminates subjected to low velocity impact at three dffirent energy levels are discussed in detail.
Analytical Solution to Relativistic Rocket Motion
Authors: Maitra S.N.
Published: December 2023

Based on classical dynamics, motion of rocket called Newtonian Rocket is contemplated in the sense of framing its differential equations of motion. These differential equations of motion of rocket have been modified in the light of theory, of relativity applying Lorentz's transformation and have velocity of rocket but considerably less than the velocity of light to determine its propellant mass, velocity and distance travelled. A table with numerical has been prepared comparing the performance of the relativistic rocket with its Newtonian counterpart. On the whole the present paper deals with rocket dynamics in vacuum and gravitation-less space, coupled with continuous decrease in mass due to the propellant consumption and due to relativistic effects.
Numerical Simulation of a Sonic Jet Injected into a Supersonic Crossflow With K.(l) Turbulence Model
Authors: Sriram A.T. , Mathew Joseph
Published: December 2023

Numerical simulation of normal injection of a sonic jet into supersonic crossflows were performed with a k-ul turbulence model. Favre-averaged Navier-Stokes equations along with k-6p equations were solved in a coupled manner by calculating inviscidfluxes with Roe's flux-dffirence splitting, central dffirencing of derivatives in the viscous terms, and by performing Runge-Kutta time integration in a finite volume formuLation. Experiments of sLot injection at several freestream Mach numbers and injection pressure ratios were simulated. It was observed that simulations agreed well at low pressure ratios but departed with increasing pressure ratio as had been observed in other simulations. A qualitative difference in the structure of the jet was observed when explicit compressibility fficts were included. In turn, the agreement with experiment improves significantly. It was also observed that imposing a lower ReynoLds number in the caLculations than the value determined from reported experimental conditions resulted in solutions expected of transitional separation and vvhich then agreed more closely with experiment.
Behaviour of Shear Deformable Plate Bending Finite Elements for Composites
Authors: Latheswary S. , Valsarajan K.V. , Sadasiva Rao Y.V.K.
Published: December 2023

A thorough study of the behaviour of shear deformable plate bending finite elements is carried out to investigate their performance when applied to static and free vibration analyses of Iaminated composite plates. 4-noded, 8-noded and 9-noded quadrilateral isoparametricfinite elements based on first-order shear deformation theory and a 4-noded element based on higher-order shear deformation theory are considered. The numerical results indicating the effect of order of integration on the accuracy of the results and convergence of transverse displacements and stresses are presented. The resuLts indicate that a 4-noded element with seven degrees offreedom per node based on higher-order shear deformation theory is required to predict the deflection as well as the stresses accurately and a I 6x I 6 mesh division for full plate is necessary for obtaining converged resuLts. For the case offree vibration analysis, the element based onfirst-order shear deformation theory is found to be sufficient.
Lifting Re-entry Trajectory Optimization
Authors: Kumar Arora Rajesh , Adimurthy V , Ananthasayanam M R , Bhat M S
Published: December 2023

Trajectory optimization of a lypical RLV technology demonstrator is formulated as an optimal control problem. Both planar and out of plane trajectory optimization is carried out during re-entry phase using steepest descent method. Dynamic pressure and lateral acceleration are used as inequality constraints. Terminal equality conslraints on altitude and velocity are also specifed. Constraints qre included in the performance index as exterior penatty functions. Detailed formulations of the optimal control problem along with results are presented in this paperfor some test cases.
Buckling of Laminated Composite Cylnidrical Panels Ijnder Transverse Load
Authors: Sai Ram K.S. , Sreedhar Babu T.
Published: December 2023

The bubHing of laminated composite cylindrical shell panels subjected to transverse load is investigated. The geometrical non-linear analysis is carried out using thefinite element method based o,n a higher-order shear deformation theory. An eight nodded degenerated isoparametric shell element with nine degrees of freedom at each node is considered. The geometric non-linear behaviour and the collapse pressures ere presented for symmetrically and antisymmetrically laminated cross-ply and angle-ply cylindrical shell panels subiected to uniform normal pressure.
Shimmy Studies on Simplified Linear Nose-wheel Landing Gears Models
Authors: K Sura Niranjan , Suryanarayan S
Published: December 2023

Multiplicity of parameters and complexity of various component models have made modelling and analysis of Landing gear dynamics a very complex task. This paper presents a study of shimmy instability on a simplified linear three degree-of-freedom model of a nose-wheel landing gear. The simplified model considers cornering forces due to tire lateral displacement but ignores forces due to tire twist. This study is carried out as a forerunner to stability studies with detailed tire models along with tire skid. The stability of the system is studied by root locus plots in the complex plane for different values of forward velocity. These studies bring out the role of landing gear torsional/flexibility, viscous damping, caster length and tire lateral flexibility and damping on shimmy oscillations.
100 Years Since First Powered Flight - Aeronautical Society of India Commemorates the Event
Authors: . .
Published: December 2023

On 17 Dec 1903, a flight of 12 seconds covering a distance of 120 Ft (37 M) changed history. The Wright Brothers had flown the first manned, powered heavier-than-air flying machine. The Aeronautical Society of India celebrated the momentous occasion of " 100 years since First Powered Flight" in a befitting manner with two major events. The first event organized by the Society was "Air Race India 2003" between November 20-22,2003. The Society organized a two day event on December 17-18, 2003 at Bangalore, the birth place of the Society, and are International Seminar on " 100 years since First Powered Flight" and a Technical Seminar on "Advances in Aerospace Sciences". The Society also held its 55th Annual General Meeting. Shri NR Mohanty, President, The Aeronautical Society of India handed over the Presidentship to Air Chief Marshal, S. Krishnaswamy, PVSM, AVSM, VM & Bar ADC at the 55th Annual General Meeting.
Kalpana : the Power of Imagination
Authors: Sharma, AC Rakesh Sharma, AC*
Published: December 2023

I stand before you, with mixed feelings. As an aviator, even though one who is now done with aviation, I recognize the momentous occasion that this is: the centennial of powered flight, a celebration of the day a 100 years ago when the Wright flyer took to the air for the first time. Then again, as an Indian and a Space buff, like most everybody on this Planet, I grieve the passing on of Kalpana Chawla and her 6 colleagues who perished when Columbia started disintegrating over Texas on 0l February this year. While on the one hand I am amazed, in technological terms, of the advancement achieved in the field of Aerospace in the hundred years just gone past, as a professional I remain curious and very interested in knowing what exactly went wrong with Columbia; what the contributory factors were and whether there is a message embedded for us, somewhere in the pages of the voluminous investigation report.
Four Decades of Indian Launch Vehicle Technology
Authors: Madhavan Nair G
Published: December 2023

I am extremely happy to be with you this evening and feel proud and honoured to have the opportunity to deliver the Neelakantan Memorial lecture organized by the Aeronautical Society of lndia on the occasion of the Centennial celebration of the 'First engine-powered heavier-than-air aircraft flight by the Wright Brothers'.
A Study of Interaction of Five Supersonic Jets
Authors: Ramjee V. , Sasi Kumar S. , Sundararajan T. , Rajesh G.
Published: December 2023

The spreading features of five supersonic jets, in the configuration of one central bigger jet surrounded by four smaller equi-distant peripheral jets have been studied numerically and experimentally for different Mach numbers and spacing ratios. The computed values are in good agreement with the experimental results. The jets maintain their individual behavior up to twelve diameters and thereafter they merge to form a single jet. For smaller spacing ratio and lower Mach number, the merger occurs earlier compared to higher spacing ratio and larger Mach number. The mass flux rate increases with the spacing ratio. The Reynolds shear stress and turbulent kinetic energy are higher for under expanded jets than for correctly expanded jets and over expanded jets.
Development of 3-D Computer Code to Study Autoignition in a Turbulent Medium
Authors: Sreedhara S.
Published: December 2023

In. this paper, the development and validation of 3-dimensional computer code to analyze autoignition in a non-premixed medium under isotropic and homogeneous turbulence is presented. During autoignition the density changes are considerable and hence the constant density assumption cannot be made. To incLude the effects of density, fluctuations caused due to spatial inhomogeneities in temperature and species, a pressure based method is deveLoped herein, which is a spectral impLementation of the sequential steps followed in the predictor-corrector type of algorithms. The velocity and pressure field are solved in spectral space while the scalars are solved in physical space. The combustion is assumed to take pLace through a single-step irreversible reaction. Simulations are first validated for nonreacting turbulence without any scalars. Next, the decay, of scalar variance has been studied which showed a power law decay as observed by the earLier researchers. Then. the program is extended to analyze the reacting flow problems. The code has been parallelized using MPI calls to run it efficiently on IBM-SP machines. The details of the governing equations, solution methodology and comparison of present results with previous data are presented.
Influences of Functionally Graded Materials on Supersonic Panel Flutter
Authors: Prakash T. , Ganapathi M. , Singha Maloy K.
Published: December 2023

Here, the supersonic flutter behavior of flat panels made of functionally graded materials is studied. The structural model is based on first-order shear theory and material properties are assumed to be temperature dependent and graded in the thickness direction. The aerodynamic force is evaluated by considering the first-order high Mach number approximation to linear potential flow theory. The variation of critical aerodynamic pressure is highlighted considering different parameters such as plate thickness, aspect ratio, power law index of functionally graded materials, temperature-dependent material properties. It is seen that the volume fraction index plays a significant role on the critical flutter speed under thermal environment.
The Role of Gas Path Diagnostics in the Changing Gas Turbine After-market
Authors: Singh Riti
Published: December 2023

Aero gas turbine maintenance strategies are likely to see profound changes in the future. The remarkable size of the aftermarket for both military and civil aero gas turbines has already changed the nature of the business case. The aftermarket is large, more lucrative and not subject to the cyclical downturns of the original equipment sales. The competition which this considerably profitable after market creates will spur advances in diagnostic techniques. Of particular importance is advanced gas path diagnostics where, in recent years, engineering science research has opened pathways using somewhat surprising technologies. The paper will present work covering linear and non-linear gas path analysis, genetic algorithms, neural networks, fuzzy logic and hybrid systems. Much of the costs associated with the gas turbine after market relates to the gas path and these techniques are seen to play an important role
Defensive Avionics for Fighter Aircraft - Design Considerations With Emphasis on System Installation
Authors: Bimalkhedkar S. , Durga Prasad C.H.
Published: December 2023

A fighter aircraft is vulnerable to precision radar guided weapons of the adversary Air Defences. The aircraft survivability can be enhanced only by equipping it with modern Defensive Avionics. The Defensive Avionics typically comprises wide band sensitive receivers, powerful Signal Processors and high ERP transmitters. The sensitive receivers get affected by on board transmitters and the transmitters of the Defensive Avionics may interfere with satisfactory operation of other onboard avionics. Mutual compatibility is usually ensured by suitable temporal, spectral and spatial management techniques. The restricted spaces and limited ECS for cooling the Defensive gear call for careful tradeoffs to be made. The paper addresses these considerations and tradeoffs and suggests practical solutions to ensure that Defensive Avionics suite performs its role without degrading other avionics operation.
Multidisciplinary Optimization Aerospace Design: The Emerging Technology For Complex Systems
Authors: Adimurthy V. , Balu R. , Priyadarshi Pankaj , Ramanan R.V. , Ravikumar C.
Published: December 2023

The design, development and launching of a space vehicle is a highly interdisciplinary activity, with strong interaction between aerodynamics, structures, thermodynamics, flight mechanics, navigation-guidance-control, propulsion, telemetry, range safety etc. Performance, weight and finally cost optimality are most important in these systems. The desired goals are best achieved through formal disciplinary and multi-disciplinary optimization. In the context of the Indian space vehicle design, optimization of trajectories is routinely carried out for all missions. In recent times a number of aerodynamic shape optimization problems are taken up, many of them using high fidelity CFD codes. The need to limit the launch cost drives the increasing use of multi-level and multidisciplinary design optimization. This paper discusses the class of optimization algorithms used and developed along with a few case studies on disciplinary and multi-level optimization in the trajectory design of orbital and interplanetary missions, and emphasizes the emerging trends in the multidisciplinary design optimization of aerospace systems
Piezo Mechanisms for Optical and Space Applications in Europe
Authors: Maillard T. , Le Letty R. , Barillot F. , Rajeev G.
Published: December 2023

Piezoelectric actuators find their first applications in active space optics. The purpose of this paper is to describe the state of the art and some applications. Piezo actuators display attractive features for space applications, such as precise positioning, unlubricated, non-magnetic and compact features, and low power consumption. However, piezo mechanisms cannot be considered separately from their driving and control electronic. Piezo actuators, such as Amplified Piezo Actuators or Parallel Pre-stressed Actuators, initially designed under the French Space Agency contracts, shall find their first space flight applications in optics on the first European LIDAR, to be on board on AEOLUS in 2007. - Fine pointing of the laser beams, - Laser cavity tuning. Breadboard mechanisms based on piezo actuators have also been tested for refocusing purposes. Other applications includes the improvement of the CCD resolution through an over-sampling technique, such as in the SOHO/LASCO instrument, fast optical shutter operation, optical filter in combination with a Fabry - Perot interferometer, such as in future LIDAR for earth observation. The first applications shall be described and an overview of the future potential applications shall be given. The current trend is to broaden the application fields, extending them to aeronautic optic applications
Modeling of Piezo Stack Actuators and Their Application in Active Vibration Control
Authors: Singhvi Rupal , Venkatesan C.
Published: December 2023

This paper presents the vibration control of a highly simplified two degree of freedom model of a helicopter. The vibration control study has been performed using both active and passive vibration control schemes. In the case of active vibration control, the feedback mechanism affects the stiffness of the system; whereas in passive vibration control, the absorber mass affects the inertia of the system. The active control is achieved using a combination of piezo stack sensor and actuator mechanism. A finite element model for the piezo stack mechanism has been developed to obtain a relation between deformation, applied/induced potential and externally applied mechanical load. The results of this study indicate that inclusion of sensor and actuator units increases the natural frequency of the system due to increase in stiffness of the system. It is observed that in the case of active vibration control, the frequency response of acceleration of the system is highly sensitive to small variations in the magnitude of gain around its optimum value and insensitive to changes in excitation frequency; whereas in passive vibration control, the frequency response does not exhibit any significant change in the characteristics with respect to the variation in the absorber mass, while it is highly sensitive to changes in operating frequency.
5-axes Levitation of a Rotor by Active Magnetic Bearings Employing Direct Output Feedback Control
Authors: Jana S. , Arun Kumar V.
Published: December 2023

In recent years the application of active magnetic bearings (AMB), as supporting element as well as vibration controller for rotors, has attracted considerable attention from researchers. In this work an attempt has been made for the complete levitation of a rotor weighing 4 kg, supported on two radial active magnetic bearings and two axial passive magnetic bearings (PMB) resulting in 5-axes levitation. The active bearings working in the mode of attraction make the system inherently unstable. Herein, a direct output feedback control scheme based on proportional and derivative of position signal has been employed to achieve stability. The active magnetic bearings consist of electromagnetic actuators, proximity probes for position measurement, feedback controller and current feedback type power amplifier. The passive bearings consisting of axially magnetized circular permanent magnets work in the mode of repulsion. The design of the electromagnetic actuator has been carried out considering load carrying capacity of the AMB, core loss and the resistive loss in the coil, so that the temperature rise in the core as well as in the coil is within allowable limit. Design of the feedback controller is based on direct output feedback control scheme, which makes the controller design easier and implementation of the controller hardware becomes simpler. The feedback controller parameters have been selected appropriately to generate required stiffness and damping in the AMBs for stable levitation of the rotor. The rotor has been driven up to a speed of 2000 rpm.
Analysis of Smart Composite Plates - A Finite Element Approach
Authors: Latheswary S. , Valsarajan K.V. , Sadasiva Rao Y.V.K. Sadasiva Rao
Published: December 2023

A 4-noded finite element with seven degrees of freedom per node, based on higher-order shear deformation theory, is used for the analysis of smart composite plates. This model does not include voltage/electric potential as a degree of freedom and is valid for both surface-mounted and embedded piezoelectric elements either distributed or placed in patches. The effect of actuator voltage on the static and dynamic behaviour of such plates is studied. It is seen that the reduction in deflection is proportional to the actuator voltage and the actuator voltage does not have significant influence on the frequency of vibration. An active control of vibration is achieved by suitably amplifying the voltage sensed by the sensor.
A Simple Strain Recovery based A-posteriori Error Estimator for Laminated Composite Plates
Authors: Upadhyay C.S. , Mohite P.M.
Published: December 2023

A globally and locally reliable strain recovery based a-posteriori error estimator for laminated composite plates is proposed in this study. An extensive check of the local and global quality of the proposed error estimator is carried out for the bending problem. Effect of material orientation, ply stacking sequence, boundary condition and loading profile is carried out for a square plate. It is found that this estimator is reliable for almost all the cases, and even predicts errors for the preasymptotic range reliably.
On the Dynamic Snap-through Buckling of Functionally Graded Spherical Caps
Authors: Sundararajan N. , Ganapathi M.
Published: December 2023

Here, the dynamic snap-through buckling characteristics of clamped functionally graded spherical caps suddenly exposed to a thermal field are studied using finite element procedure. The material properties are graded in the thickness direction. The temperature load corresponding to a sudden jump in the maximum average displacement in the time history of the shell structure is taken as the dynamic buckling temperature. Numerical study is carried out to highlight the influences of shell geometries and material gradient index on the critical buckling temperature.
Effect of Geometrical Parameters on the Exit Pattern Factors Of An Annular Combustor: An Experimental Study
Authors: R. K. Mishra  , R. D. Navindgi  , Kuldeep Singh
Published: December 2023

Combustor is an important component of a gas turbine engine and its performance governs the overall performance of the engine. Combustor exit pattern factors are very critical from the consideration of turbine blade and vane life. To achieve the desired goal of pattern factors, the air-management through different zones of combustor is to be carried out very carefully with proper fuel-air mixing followed by complete combustion in the primary zone. During the development stage, extensive studies have been carried out to establish the effect of different geometrical parameters of the combustor on the exit pattern factors. This paper describes the details of the experimental investigations carried out on a full- scale combustor with different geometrical parameters such as diffuser geometry, swiller configuration, atomizer flow passage and dilution zone configurations to study their effect on the exit pattern factors. Dilution zone geometrical parameters and swirler configuration are found to have strong influence in controlling the combustor exit pattern factors and there is an optimum size and spacing of the dilution holes to achieve desired pattern factors at combustor exit.
Computation of Heat Flux in Hypersonic Flow with a Cartesian Mesh Using Near-Wall Resolution
Authors: Ashok V. , Joseph George , Adimurthy V.
Published: December 2023

A hybrid solution methodology is developed to solve laminar hypersonic flow with a Cartesian mesh approach. The hybrid grid consisting of a Cartesian mesh together with an unstructured prism layer near the wall to capture the large gradients close to the surface is used for the near wall viscous resolution. The prism layer is generated by extruding the panels formed by the intersection of the Cartesian grid and the body and is stitched with the outer Cartesian mesh away from the wall for solving axi-symmetric flows. For three dimensional flows, since the prism layer cells are not stitched to the outer Cartesian mesh, the inviscid solution is carried out first for background Cartesian mesh and later this solution is mapped to the extruded prism layer cells and laminar Navier-Stokes solution is carried out for the prism layer cells alone. The developed solver gives an unstructured prism layer solution near the wall and standard Cartesian mesh solution away from the wall. This hybrid solution methodology is validated against the experimentally measured heat flux data and could predict the heat flux with good accuracy. The present methodology thus enables the computation of a viscous solution using a Cartesian mesh based approach.
Prediction of Helicopter Blade Loads for an Unsteady Pull-Up Maneuver Using Lifting-Line and CFD/CSD Analyses
Authors: . Abhishek
Published: December 2023

This paper investigates the aeromechanics of a prescribed 2.1g pull-up maneuver for a helicopter rotor. The simulation is carried out using multibody based Computational Structural Dynamics (CSD) model tightly coupled to a high-fidelity Computational Fluid Dynamics (CFD) solver. The predictions are also compared with those obtained using lifting-line based comprehensive analysis to highlight the capabilities of a high-fidelity simulation. The results show considerable improvements in the predicted results by using a CFD model over a traditional lifting-line approach. In particular, coupled CFD/CSD simulation is able to correctly predict the magnitude and phasing of the two dynamic stall cycles on the retreating side of the rotor disk during the maneuver. Further, it shows significant improvement in the predicted peak-to-peak structural loads. The advancing blade stall is not predicted by either of the analysis. The study also shows some deficiencies in the ability to predict blade torsional loads.
Investigation of the Effect of Cavitator Angle and Dimensions for a Supercavitating Vehicle
Authors: Sri Raman A. , Ghosh A.K.
Published: December 2023

At very high speeds, bubbles form on the body of underwater vehicles because of sharp trailing edges or at places where the local pressure is lower than the vapor pressure. These bubbles are called cavities and the size of the cavities grows as the velocity increases. A properly designed cavitator can induce the formation of a single big cavity all over the vehicle. Such a vehicle travelling in the vaporous cavity is called a supercavitating vehicle and the present research work mainly focuses on the dynamic modeling of such vehicles. Cavitation of the fins is also accounted and the effect of the same on trajectory is well explained. The entire dynamics has been developed using the state space approach and emphasis is given on the effect of size and angle of attack of the cavitator. Control law has been established for the motion of the vehicle using Non-linear Dynamic Inverse (NDI) method with cavitator as the control surface.
Postbuckling Strengths of Composite Laminates with a Central Circular/Elliptical Cutout Under In-Plane Combined Loads
Authors: Kumar Dinesh , Singh S.B.
Published: December 2023

This paper deals with the effect of cutouts (i.e., circular and elliptical) aspect ratio on the buckling and postbuckling strengths, and failure characteristics of a simply-supported quasi-isotropic composite laminate subjected to in-plane shear and uni-axial compression combined with in-plane shear loads. The present study is carried out using self developed finite element program. The finite element formulation is based on the first order shear deformation theory and von Karmans assumptions to incorporate geometric nonlinearity. The resulting nonlinear algebraic equations are solved by Newton-Raphson method. The postbuckling strength of the laminate is defined in terms of the first-ply failure load of the lamina predicted by tensor polynomial form of the 3-D Tsai-Hill criterion. It is observed that for maximum buckling and first-ply failure strengths of the laminate with a cutout, it is preferred to have elliptical shape of the cutout as compared to the circular shape of the same area. It is also found that irrespective of load conditions and cutout shapes and sizes, shear load direction has significant effects on buckling and postbuckling stiffness of the laminate; although buckling stiffness is greater under negative shear, but the laminate shows stiffer postbuckling response under positive shear load.
Flight Envelope Expansion during Prototype Development
Authors: Deepa M.S. , Gupta S.C.
Published: December 2023

Certification configuration loads are discussed. Flying commitments for unstable fighter aircraft deploying stability augmentation are brought out. Some aspects related to data generation through wind tunnel testing and flight simulation are highlighted. Flight test points for the flight envelope expansion and related criterion are explained. Fault tolerant flight control system testing is covered. The aerodynamic considerations are largely dealt herein for the purpose of flight envelope expansion for the prototype fighter programs.
Decision Fusion Using Fuzzy Logic Type 1 for Two Aviation Scenarios
Authors: Raol J.R. , Kashyap Sudesh K
Published: December 2023

In this paper we discuss some aspects of decision fusion using fuzzy logic of type 1 for two aviation scenarios. We study the fuzzy inference system/engine and briefly discuss the MATLAB-GUI based tool developed by the authors to evaluate any existing or new fuzzy implication functions. Two examples: i) formation flight, and ii) flying along an air lane are numerically evaluated and the performance of decision fusion systems incorporating fuzzy logic is illustrated. The results indicate that some existing as well as new implication functions, devised by the authors, work very well for the examples considered. This opens up new possibilities of applications of fuzzy logic based decision fusion to varieties of aerospace/aviation problems in data fusion, decision making, and decision fusion.