Courses

ME682 - Seminar (0 + 0) 5

Each PhD student is expected to give a presentation on his/her thesis work and attend the seminars conducted by the other students and academic staff.

ME689 - Qualification Exam (0 + 0) 30

The contents of the required courses in the Ph.D program.

ME691 - Thesis Proposal (0 + 0) 20

The research area in the topic of mechanical engineering.

ME697 - Doctoral Thesis (0 + 0) 150

Areas in the thesis protocol.

CE521 - Applied Solid Mechanics (3 + 0) 5

Analysis of stress and strain, stress-strain relations, plane strain and plane stress problems, yield and failure criteria, unsymmetrical bending of beams, energy methods, buckling of columns, plastic behavior of structural members.

CMPE525 - Object-Oriented Design and Programming (3 + 0) 5

Thinking object-oriented, abstraction, object-oriented analysis and design concept, design patterns, UML: introduction, role of modeling, models and views, core diagrams, fundamental elements, sequence, class, and package diagrams, development lifecycle, Java and UML: Responsibility-Driven Design (RDD), and CRC, classes, messages, inheritance, sub

CE566 - Advanced Mathematical Methods in Civil Engineering (3 + 0) 5

First-, second- and higher-order linear ordinary differential equations, system of differential equations, power series solution of differential equations, Laplace transforms, partial differential equations, numerical integration and derivation, numerical solution of differential equations.

CMPE564 - Natural Computing (3 + 0) 5

Problem solving by search, hill climbing, simulated annealing, artificial neural networks, genetic algorithms, swarm intelligence (including ant colony optimization and particle swarm optimization), artificial immune systems.

CEAC503 - Advance Inorganic Chemistry (3 + 0) 5

Bronsted and Lewis acid-base concepts, coordination chemistry, molecular structures, point group reactions, redox reactions.

EE504 - Introduction to Systems Analysis (3 + 0) 5

Review of linear algebra concepts, classifications of systems and system representations, continuous and discrete time systems, state space realizations, analysis techniques: frequency domain, Laplace and z-domain analyses, solutions of linear systems, stability analysis; assessment of the techniques by a computational tool such as MATLAB.

IE503 - System Analysis and Design (3 + 0) 5

Requirements engineering and modeling, structural modeling, system architecture and user interface design, documentation, testing and installation, traceability, project planning and management.

IE509 - Production Systems (3 + 0) 5

Management and control of production function in organizational systems, concepts of materials management, master production scheduling and production planning from different perspectives, aggregate planning, lot sizing, scheduling in manufacturing systems, scheduling in service systems, design and operation of scheduling systems, material requirem

MATH587 - Applied Mathematics (3 + 0) 5

Calculus of variations: Euler-Lagrange equation, the first and second variations, necessary and sufficient conditions for extrema, Hamilton`s principle, and applications to Sturm-Liouville problems and mechanics; integral equations: Fredholm and Volterra integral equations, the Green?s function, Hilbert-Schmidt theory, the Neumann series and Fredho

MATH552 - Complex Analysis (3 + 0) 5

Analytic functions as mappings, conformal mappings, complex integration, harmonic functions, series and product developments, entire functions, analytic continuation, algebraic functions.

MFGE505 - Practical Finite Elements (Linear Finite Element) (3 + 0) 5

Background and application of FE, direct approach, strong and weak forms, weight functions and Gauss quadrature, FE formulation for 1D problems, plane strain/stress and axisymmetric problems, displacement based FE formulation, isoparametric elements, performance of displacement based elements and volumetric locking; reduced selective integration.

MFGE541 - Theory of Metal Cutting (3 + 0) 5

Introduction, machine tools and machining operations ?turning, drilling and milling, abrasive machining, mechanics of metal cutting; tool life and tool wear, economics of metal cutting operations, chip control, machine tool vibrations, grinding.

MFGE542 - Theory of Metal Forming (3 + 0) 5

Elements of the theory of plasticity, fundamentals of metal working, forging process, rolling process, extrusion process, drawing of rods, wires and tubes, sheet metal forming process, high energy rate forming.

MFGE543 - Theory of Sheet Metal Forming and Die Design (3 + 0) 5

Material properties, sheet deformation processes, deformation of sheet in plane stress, simplified stamping analysis, load instability and tearing, bending of sheet, simplified analysis of circular shells, cylindrical deep drawing, stretching of circular shells, combined bending and tension of sheets, hydroforming, introduction to finite element an

MFGE576 - Nonlinear Finite Element Method (3 + 0) 5

Review of the linear FE-concepts, solution of nonlinear equations, one-dimensional nonlinear problems, two/there-dimensional rigid-plastic finite element solution, two/three-dimensional large-strain elasto-plastic FE-solutions.

MFGE577 - Quality Control and Metrology (3 + 0) 5

Elementary metrology, linear-angular and comparative measurement, instruments and gauges for testing straightness, flatness, squareness, parallelism, limits, fits and gauges, inspection, quality function in industry, fundamentals of statistical concept in quality control, control charts in SQC, sampling inspection, operation characteristics (OC) cu

MFGE508 - Boundary Element Method (3 + 0) 5

Introduction, preliminary concepts, vector and tensor algebra, indicial notation, divergence theorem, Dirac delta function; singular integrals, Cauchy principal value integrals in 1 and 2D, boundary element formulation for Laplace equation, Laplace equation; discretization, boundary element formulation for elastostatics, elastostatics, discretizati

MFGE534 - Distortion Engineering (3 + 0) 5

Distortion, distortion potential, distortion potential carriers, compensation potential, production step based solutions, intelligent process chain design, predictive methods, use of in-situ measurement techniques and adaptive process control.

MFGE547 - Mechanical Characterization of Metals I (3 + 0) 5

Introduction, background and application of mechanical characterization metals, review of the mechanical behavior metals, review of mechanical testing equipment, tensile test, compression test, hydraulic bulge test, high temperature mechanical testing, determination of elastic properties, flow curves and planar anisotropy for sheets.

MFGE549 - Experimental Stress Analysis (3 + 0) 5

Review of elasticity fundamentals, strain measurement methods, gauge selection, bonding surface preparation, strain gauge circuits, sources of error, strain gauge excitation levels, force, torque and pressure measurements, special-purpose gauges, rosette analysis, corrections for transverse effects, industrial applications.

MFGE560 - Pre-Stress Engineering (3 + 0) 5

Residual stresses, measurement techniques, effect of residual stresses, residual stress control, pre-stressing techniques.

MFGE561 - Surfaces and Interfaces (3 + 0) 5

Interfacial forces, thermodynamics of interface, study of solid surfaces, interfaces between liquid and solid, surface cleaning methods, surface wear, plating and coating methods, marine biofouling, advances in anti-fouling marine and biomaterial surfaces, smart surfaces.

MDES610 - Mathematical Modeling via Differential and Difference Equations (3 + 0) 5

Differential equations and solutions, models of vertical motion, single-species population models, multiple-species population models, mechanical oscillators, modeling electric circuits, diffusion models, modeling by means of difference equations.

MDES615 - Analytical Probability Theory (3 + 0) 5

Sigma-algebra of sets, measure, integral with respect to measure; probability space; independent events and independent experiments; random variables and probability distributions; moments and numerical characteristics; random vectors and independent random variables; convergence of random variables; transform methods; sums of independent random v

MDES618 - Probabilistic Methods in Engineering (3 + 0) 5

Basic notions of probability theory, reliability theory, notion of a stochastic process, Poisson processes, Markov chains, statistical inference.

MDES620 - Numerical Solution of Differential Equations (3 + 0) 5

Numerical solution of initial value problems; Euler, multistep and Runge-Kutta methods; numerical solution of boundary value problems; shooting and finite difference methods; stability, convergence and accuracy; numerical solution of partial differential equations; finite difference methods for parabolic, hyperbolic and elliptic equations; explic

MDES621 - Numerical Linear Algebra (3 + 0) 5

Floating point computations, vector and matrix norms, direct methods for the solution of linear systems, least squares problems, eigenvalue problems, singular value decomposition, iterative methods for linear systems.

MDES630 - Estimation and Identification for Engineering Systems (3 + 0) 5

Kalman filtering, nonparametric identification techniques and parameter estimation methods; implementation of filtering algorithms on physical systems and collecting data from real systems.

MDES631 - Engineering Decision and Risk Analysis (3 + 0) 5

Basic notions of probability, random variables, functions of random variables distributions, moments; first and second-order approximations; probability models for engineering analysis; Bernoulli sequence, binomial distribution, Poisson and related distributions, normal and related distributions, extreme-value distributions, other distributions us

MDES640 - Advanced Theory of Engineering Design (3 + 0) 5

Determination of the customer needs and the real design problem; engineering creativity; generation of innovative solution alternatives, and selection of the effective solution; modularity in design; collaboration in interdisciplinary design tasks; concepts of systems, models, and strategies for purposeful activities; design and control of design p

MDES641 - Biomimetic and Bioinspired Engineering Design (3 + 0) 5

definitions, terminology and concepts in biomimetics; review of biological systems for kinematic and dynamic analysis, for structural analysis, and for behavioral modeling; reverse engineering as applied to biological systems; mapping concepts of biological systems on the engineering systems; theories and application principles of modeling and scal

MDES650 - Advanced System Simulation (3 + 0) 5

Discrete simulation models for complex systems, input probability distributions, random variable generation, statistical inferences, variance reduction, continuous processes, verification and validation, advanced models.

MDES651 - Boundary Element Method Programming (3 + 0) 5

Vector calculus; boundary value problems in mechanics; general outline of boundary element formulation; direct and indirect formulations; discretization-elements and integration; assembly and solution techniques; advanced techniques-dual reciprocity and multiple reciprocity, substructuring and boundary element-finite element coupling; parallel prog

MDES652 - Design and Modeling of Casting and Solidification Processes (3 + 0) 5

Theoretical background including fundamentals of casting process modeling, stress analysis, defect formation, microstructure evolution, thermophysical properties, and quick analysis techniques to solve casting problems; applications to shape castings, ingot castings and spray forming.

MDES654 - Decision Making Analysis (3 + 0) 5

Conflicting objectives in decision making; decision problems under certainty; utility theory for single-attribute and multi-attribute problems in decision analysis; individual versus group decisions.

MDES655 - Linear Optimization (3 + 0) 5

Sets of linear equations, linear feasibility and optimization, local and global optima, the Simplex method and its variants, theory of duality and the dual-Simplex method, network-Simplex algorithms, computational complexity issues and interior-point algorithms.

MDES656 - Nonlinear Optimization (3 + 0) 5

Linear algebra and polyhedral sets, duality and the theorems of the alternative, convex sets and convex functions, line-search methods, unconstrained optimization, optimality conditions; steepest descent, Newton, quasi-Newton and conjugate-gradient algorithms; constrained optimization and optimality conditions; the reduced gradient method; penalty

MDES662 - Advanced Natural Computing (3 + 0) 5

Evolutionary computing, ant colony optimization, particle swarm optimization, artificial bee colonies, cellular automata, L-systems, artificial life, DNA computing.

MDES663 - Chemical Computations (3 + 0) 5

Coordinate systems; definition of theory, computation and modeling; units used in computational chemistry; potential energy surfaces; theoretical structures; mathematical concepts; hardware and software; foundations of molecular orbital theory; semiempirical implementations; density functional theory; ab initio implementations, thermodynamic proper

MDES665 - Chemical Thermodynamics of Materials (3 + 0) 5

Advanced treatment of the thermodynamic properties of inorganic materials; laws of thermodynamics and their application to the chemical behavior of materials systems; multicomponent systems, phase and chemical reaction equilibria; thermodynamics of phase transformations; introductory surface thermodynamics.

MDES672 - Advanced Topics in Digital Image Processing (3 + 0) 5

Review of image processing fundamentals, frequency and space domain image processing methods; wavelets, multiresolution processing, and orthogonal transforms; image and video compression standards; image segmentation and representation; nonlinear image processing methods.

MDES674 - Supply Chain Management (3 + 0) 5

Supply chain management purposes and processes; supply chain design, evaluation and measurement models; trends in strategic operations, procurement, and logistics applications within the supply chain.

MDES677 - Advanced Artificial Intelligence (3 + 0) 5

Intelligent agents, problem solving by searching, informed/uninformed search methods, exploration, constraint satisfaction problems, game playing, knowledge and reasoning: first-order logic, knowledge representation, learning, selected topics: evolutionary computing, multiagent systems, artificial neural networks, ant colony optimization.

MDES678 - Theory of Continuous Media I (3 + 0) 5

Review of tensor analysis and integral theorems; kinematics of deformation, strain tensor, compatibility condition; material derivative, deformation rate, spin and vorticity tensor; external and internal loads, Cauchy?s principle and stress tensors; basic laws of continuum mechanics (conservation of mass, continuity equation, principle of linear an

MDES679 - Theory of Continuous Media II (3 + 0) 5

Energy an virtual work equations, second law of thermodynamics, entropy, reversible and irreversible processes; theory of thermoelasticity, Gibbs relation; adiabatic and isothermal deformations; Clausius-Duhem inequality; constitutive equations, material symmetry restrictions; theory of viscoelasticity, theory of plasticity; applications.

MDES683 - Theory of Plasticity (3 + 0) 5

Vector and tensor calculus; general concepts about mechanics of materials-stress and strain concept; continuum deformation: displacement, strain and compatibility conditions; mechanics of continuous bodies: stress and stress equation of motion; elastic constitutive relations; inelastic constitutive relations; yield criteria, flow rules and hardenin

MDES686 - Fundamental Principles of Tissue Engineering (3 + 0) 5

Cell-tissue concepts, cell-tissue culture basic principles, tissue engineering, biomaterials, systems, proteins, biomaterial surface interactions, tissue microenvironment, organ loss and regeneration.

SE560 - Requirements Engineering (3 + 0) 5

Domain understanding and requirements eliciation; requirements evaluation; requirements specification and documentation; requirements quality assurance; requirements evolution; modeling system objectives with goal diagrams; risk analysis on goal models; modeling system agents and responsibilities; modeling system behaviours; integrating multiple sy

SE571 - Agile Software Development Approaches (2 + 2) 5

Introduction to agile methods; extreme programming (XP); Lean, Scrum; Crystal; feature-driven development (FDD); Kanban; dynamic systems development method (DSDM); architecture and design issues in agile software methods.

ME661 - Theory of Continuous Media I (3 + 0) 5

ME673 - Distortion Engineering (3 + 0) 5

ME601 - Advanced Mathematics for Engineers (3 + 0) 5

The objective of this course is to improve the skills of students in mathematics in advanced topic such as linear spaces and operators, matrix algebra, tensor fields, complex analysis and calculation of variations.

MFGE544 - Advanced Tool Design (3 + 0) 5

Tool design; tool materials; cutting tool design; workholding principles; jig design; fixture design; power presses; metal cutting, forming and drawing; tool design for inspection and gauging; tool design for joining processes; modular and automated tool handling; the computer in tool design; geometric dimensioning and tolerancin

CEAC554 - Electrochemical Methods: Fundamentals and Applications (3 + 0) 5

General electrochemical concepts, electroanalysis, introduction to electrochemistry, equilibrium measurements, potentiometry, voltammetry, coulometry, chronometry, polarography, rotating electrodes, rate constants of electron transfer, spectroelectrochemistry, electrochemical ESR spectrometry, impedance, electrode preparation methods, cleaning

ME684 - Finite Element Analysis of Solids and Fluids I (3 + 0) 5

Concepts of finite element analysis such as principle of virtual work, finite element solution procedures, heat transfer analysis, finite element analysis of solids, fluids and structures.

MDES642 - Materials and Process Selection in Design (3 + 0) 5

Design process, steps of design, design tools, designing against failure, materials and process selection in design, case studies in materials and process selection; quality, safety and economical considerations; material property charts, multiple constraints and conflicting objectives, selection of material and shape, designing hybrid materials, p

ME610 - Computer Aided Machine Design (3 + 0) 5

The objective of this course is to improve the research and communication skills of students early in their graduate program to help them better plan, conduct and present their research and thesis work.

ME611 - Nuclear Engineering I (3 + 0) 5

Atomic energy, radioactivity, neutron cross sections, neutron-atom interactions, neutron scattering, nuclear fission and fusion reactions, basic principles of neutron diffusion theory, nuclear power plants and classification.

ME612 - Nuclear Engineering II (3 + 0) 5

The course covers time dependent diffusion theory, multi-group diffusion theory, neutron transport theory, fusion cross sections, fission and fusion reactors, nuclear power plant operation. The objective of this course is to introduce time dependent diffusion theory, multi-group diffusion theory, neutron transport theory, fusion cross sections

ME621 - Advanced Fluid Mechanics (3 + 0) 5

This course is a survey of principal concepts and methods of fluid dynamics. Topics include mass conservation, momentum, and energy, equations for continua; Navier-Stokes equation for viscous flows; similarity and dimensional analysis; lubrication theory; boundary layers and separation; circulation and vorticity theorems; potential flow

CE523 - Optimization in Civil Engineering (3 + 0) 5

Formulation of Optimization Problems; Classification of Optimization Problems; Traveling Salesman Problem; Geotechnical, Hydraulic and Water Resources, Transportation, Structural, Project Management Applications of Optimization.

ME633 - Heat Transfer with Phase Change (3 + 0) 5

The mathematical formulation of phase change problems, non-dimensional parameters for phase change problems, analytical solutions of phase change problems; integral method; numerical solutions of phase change.

ME635 - Numerical Methods in Heat Transfer (3 + 0) 5

The determination of the roots of equations numerically, solving nonlinear equation systems numerically, numerical integration, using finite difference methods for differential calculations, solving ordinary differential equations numerically, applying finite difference method to heat transfer applications, least squares method.

ME641 - Advanced Thermodynamics (3 + 0) 5

First law of thermodynamics, second law of thermodynamics, entropy, exergy, reversible and irreversible processes, thermodynamic analysis of processes, power generation, entropy generation minimization.

ME651 - Energy Sources and Sustainability (3 + 0) 5

The energy use in the view of sustainability, resource availability, technical performance, environmental effects, and economics; fossil fuels: coal, petroleum and natural gas; renewable energy sources: solar, wind, geothermal, tidal, biomass and hydro; nuclear power.

ME652 - Energy Systems Optimization (3 + 0) 5

The fundamentals of optimization, graphical optimization, linear and non-linear programming, unconstrained and constrained optimization, global optimization, MATLAB applications, case studies in energy systems engineering.

ME653 - Advanced Power Systems Analysis (3 + 0) 5

The definitions of stability in energy systems, simulation methods, swing equation, equal area criterion, mathematical model of synchronous machines, excitation and mechanical regulator models, multi-machine system modeling, numerical methods, and stability analysis of single and multi-machine systems.

ME654 - Advanced Topics in Energy Management (3 + 0) 5

The fundamental concepts in energy management, Turkey's energy status, energy audit methodology, engineering economics, energy modeling, relations between energy environment economics, energy saving and demand management applications, building HVAC systems and energy efficiency, energy efficiency in industry, renewable energies and energy efficiency.

ME665 - Computational Mechanics of Materials I (3 + 0) 5

The fundamental concepts of computational mechanics of materials, basic rheological models, elasticity, viscosity and plasticity concepts, basic numerical algorithms and discretization techniques.

ME666 - Computational Mechanics of Materials II (3 + 0) 5

Concepts of computational mechanics of materials, such as 3D constitutive approaches for elasticity, viscoplasticity, damage, fatigue and creep modeling, finite strain theory

ME667 - Theory of Plasticity (3 + 0) 5

Vector and tensor calculus; general concepts about mechanics of materials - stress and strain concept; continuum deformation: displacement, strain and compatibility conditions; mechanics of continuous bodies: stress and stress equation of motion; elastic constitutive relations; inelastic constitutive relations; yield criteria, flow rules and hardening.

ME668 - Theory of Metal Forming (3 + 0) 5

ME669 - Theory of Metal Cutting (3 + 0) 5

Introduction; machine tools and machining operations; turning, drilling and milling, abrasive machining; mechanics of metal cutting; tool life and tool wear; economics of metal cutting operations; chip control; machine tool vibrations; grinding; manufacturing systems and automation; computer aided manufacturing.

ME671 - Advanced Tool Design (3 + 0) 5

ME672 - Sheet Metal Forming and Die Design (3 + 0) 5

ME674 - Transport Phenomena in Materials Processing (3 + 0) 5

Vector and tensor notations, momentum transport, equations of change for isothermal systems, energy transport, mass transport.

ME675 - Principles of Polymer Processing (3 + 0) 5

Mechanical and physical properties of polymers, polymer melt rheology, elementary steps in polymer processing, shaping.

ME677 - Quality Control and Metrology (3 + 0) 5

Elementary metrology, linear-angular and comparative measurement, instruments and gauges for testing straightness, flatness, squareness, parallelism, limits, fits and gauges, inspection, quality function in industry, fundamentals of statistical concept in quality control, control charts in S.Q.C., sampling inspection, operation characteristics.

ME678 - Global Automotive Manufacturing (3 + 0) 5

Integration of core elements of both automotive design and manufacturing, developing depth in an engineering specialty, a breadth in engineering and knowledge of basic management issues, knowledge in the product development and manufacturing of automotive systems together with thorough understanding of the fundamentals of Automotive Engineering and Science.

ME679 - Optimization Applications in Manufacturing Systems (3 + 0) 5

Introduction to the nonlinear optimization and stochastic process modeling; mathematical fundamentals of nonlinear process optimization; structure optimization: topology, form and material; introduction to nonlinear finite elements; optimization of manufacturing systems with regard to tolerances and tool loadings; optimization of dynamical systems.

ME683 - Boundary Element Method (3 + 0) 5

Introduction; preliminary concepts: vector and tensor algebra, indicial notation; divergence theorem, Dirac delta function; singular integrals; Cauchy principal value integrals in 1 and 2D; boundary element formulation for Laplace equation; Laplace equation: discretization; boundary element formulation for elastostatics; elastostatics: discretization.

ME685 - Finite Element Analysis of Solids and Fluids II (3 + 0) 5

Advanced concepts of finite element analysis such as solution methods and stability, nonlinear strain and stress measures, large deformations, iteration methods and path following techniques and coupled field problems.

ME625 - Computational Fluid Mechanics (3 + 0) 5

The formulation and application of numerical methods for solving fluid flow problems; classification of partial differential equations and formulation of well-posed problems; discrete approximation of partial differential equations: stability, consistency, and convergence; survey of methods for solving hyperbolic, elliptic, and parabolic problems.

ME626 - Computational Continuum Mechanics Applications with Open Source Software (3 + 1) 5

Introduction to Computational Continuum Mechanics; Basic Equations of Continuum Mechanics; Basic Computational Techniques; Finite Element Method; Finite Volume Method; Mesh Generation, Visualization and Post-processing in Paraview;

MATH622 - Advanced Linear Algebra (3 + 0) 5

Basic linear algebra, linear transformations, the structure of a linear operator, eigenvalues and eigenvectors, real and complex inner product spaces, structure theory for normal operators, metric vector spaces: the theory of bilinear forms, Hilbert spaces, tensor products, operator factorizations: QR and singular values.

MATH670 - Mathematical Models in Biology (3 + 0) 5

Linear and nonlinear biological models via difference equations; linear and nonlinear biological models via differential equations; special topics in mathematical biology including predator-prey models, SI,SIS,SIR epidemic models, competition models of two and three species, Van Der Pol equation, Hodgkin-Huxley and FitzHugh-Nagumo models.

ME631 - Advanced Heat Conduction (3 + 0) 5

Differential equation of heat conduction, boundary value problems, the method of separation of variables, heat conduction in semi-infinite and infinite domains, approximate analytical mehtods, numerical methods.

CE565 - Project Risk Management (3 + 0) 5

Introduction to risk, risk analysis and management, risk identification, risk assessment methods, probabilistic risk assessment, Monte Carlo Simulation, sensitivity analysis, risk response strategies.

CEAC558 - Polymer Nanocomposites (3 + 0) 5

Nano-material types, compatibility of nano-materials with polymer matrices and mixing methods, how the obtained polymer nanocomposites are produced and how these products are characterized, and the production of specific polymer nanocomposites and their literature comparisons.

MFGE545 - Intelligent Manufacturing Systems (3 + 0) 5

Integration Definition diagrams (IDEF), Unified Modeling Language (UML), Ontology Modelling (using Protégé software), Agent based systems, Java Agent Development Environment (JADE)

MDES645 - Information Systems Analysis and Design (3 + 0) 5

Introduction to software architecture; design patterns; object-oriented modeling and architectural design with contemporary notation; experimentation in design; design prototyping; working on design teams and management of object-oriented projects; detailed design and implementation issues; design reviews; using design document for coding.

MDES600 - Research Methodology and Communication Skills (3 + 0) 5

Rigorous, scholarly research, particularly theses or dissertations. Literature review, surveys, meta-analysis, empirical research design, formulating research questions, theory building, qualitative and quantitative data collection and analysis methods, validity, reliability, triangulation, building evidences, writing research proposal