Fluid Mechanics / Thermodynamics / Engineering Sciences / Aeronautics

Translated by GoogleSee original

From 33 £ /h

I am an Aeronautical engineer, graduated from the Royal Military School.

I provide private lessons in mechanics (fluids or solids), thermodynamics and engineering sciences.

Courses are mainly taught online on different platforms (zoom, skype, teams, etc.).

My goal is to help students understand and find solutions to the problems they face. I try to help them develop their own working method by giving them different elements and guiding them in the way that suits them best.

Location

Online from Belgium

About Me

I am an engineer graduated from the Royal Military School in aeronautics. Since I was little, I have always been passionate about science.

I have participated in many math/logic competitions. I love teaching and above all helping my students to overcome their difficulties, find their own working method and progress at their own pace.

I give private lessons in aeronautics, mechanics, thermodynamics, maths, physics and chemistry at all levels (primary, secondary, university and higher education).

Education

- Academic background oriented towards science
- Scientific baccalaureate (2015)
- Polytechnic engineering diploma at the Royal Military Academy (2020)
- Specialization in aeronautics

Experience / Qualifications

+ Professional experience in aeronautics
+ Private lessons since 2020
+ Advanced mathematics
+ Physics / Chemistry
+ Mechanics
+ Thermodynamics

Age

Teenagers (13-17 years old)

Adults (18-64 years old)

Seniors (65+ years old)

Student level

Beginner

Intermediate

Advanced

Duration

60 minutes

The class is taught in

French

English

Skills

Mechanical engineering

Engineering

Thermodynamics

Availability of a typical week

(GMT -04:00)

New York

Online via webcam

Mon

Tue

Wed

Thu

Fri

Sat

Sun

00-04

04-08

08-12

12-16

16-20

20-24

Private lessons in Maths, Physics and / or Chemistry

30 £ /h

I am an Aeronautical engineer, graduated from the Royal Military School.
I provide private lessons in Maths (Equations, Calculations, Trigonometry, Logic, etc...), Physics and Chemistry at all levels.
Courses are mainly taught online on different platforms (zoom, skype, teams, etc.).
My goal is to help students understand and find solutions to the problems they face. I try to help them develop their own working method by giving them different elements and guiding them in the way that suits them best.

Reza

4.64

(25)

I hold a PhD in Mechanical Engineering and currently work as a post-doctoral researcher in the Aerospace Engineering Faculty at TU Delft (Delft University of Technology).

My extensive teaching experience covers a wide range of engineering courses, including:

- Mathematics: algebra, linear algebra, probability, calculus, differential equations, intellectual math, and advanced engineering mathematics.

- Mechanical Engineering: Statics, Dynamics, Mechanics of materials, Mechanical design, control, vibration, Fluid Mechanics, Thermodynamics, Heat transfer, Engineering drawing, Applied Mechanics, Composite Structures, Flight, Machine Elements, Manufacturing, 3D printing, and more.

- Physics: mechanics, momentum and energy, electricity, charge and current, electric and magnetic fields, waves, particle physics, nuclear decay, astrophysics, cosmology, oscillations, etc.

- CAD/CAM Software: Autocad, Solidworks.

- Mechanical Design Packages: ANSYS, APDL programming, ABAQUS, MATLAB, Symbolic MATLAB, LS-DYNA.

My research and teaching interests are diverse, including:
• Additive manufacturing
• Mechanical metamaterials
• Acoustical metamaterials
• Electromagnetic metamaterials
• Aeroacoustics
• Soft matter and soft robotics
• Fatigue and fracture mechanics
• Experimental mechanics
• Multiscale numerical modelling
• Biomaterials
• Porous materials
• Manufacturing of medical devices and implants
• Deep learning
• Image processing
• Topology optimization
• Origami and Kirigami structures
• Self-folding and self-assembly structures
• Tissue engineering
• Permeability in porous materials
• Fluid-Solid Interaction

I understand that not all teachers excel in teaching Engineering and Mathematics courses and explaining their importance to students. Courses with strong mathematical backgrounds may become boring for students who lack a solid mathematical basis. To address this, I take a student-centered approach, starting from the basics to actively engage all students, including those with weaker mathematical backgrounds. I also provide practical examples to demonstrate the real-world significance of what they are learning, inspiring and fostering their interest in the subject matter.

If you have any additional questions before starting a class, please feel free to ask me. I am here to assist! :)

Anh

4.64

(25)

In these tailored Engineering sessions, I combine tutoring with mentoring to guide your technical understanding and foster your growth in key engineering concepts. My approach adapts to your natural learning style, ensuring that each lesson is intuitive, engaging, and effective.

With over 10 years of experience in Aerospace, Mechanical, and Electrical engineering, I bring a wealth of both academic and real-world expertise to our sessions. I’ll share insights from the Aerospace, Maritime, and Aviation industries to help you develop practical skills and problem-solving techniques, tailored to your needs.

Whether you're studying:
• Aerospace Engineering
• Aeronautical Engineering
• Mechanical Engineering
• Electrical Engineering
• other types of Engineering

Or need help with areas like control systems or data analysis, I’m here to guide you through any engineering challenge. My lessons are customized to fit your learning style and academic goals, ensuring you leave each session feeling confident and prepared.

Contact me now for availability, and let's schedule your first session soon. I look forward to working with you!
__________________________________________________________________________________

I'm actively supporting students from top universities worldwide, including:

UK:
• Imperial College London (+ Business School) (ICL)
• University College London (UCL)
• King’s College London (KCL)

The Netherlands:
• Delft University of Technology (TUDelft)
• University of Amsterdam (UvA)
• University of Groningen (RUG)

Switzerland:
• ETH Zurich - Swiss Federal Institute of Technology

Australia:
• Queensland University of Technology (QUT)
• University of Queensland (UQ)
• Griffith University
__________________________________________________________________________________

My name is Anh, and I was born and raised in the U.K. With over 10 years of international experience tutoring Maths, Sciences, and Engineering from Middle School to University Level, I’ve supported over 80 students worldwide in unlocking their full potential.

I have a fun, ambitious, and outgoing personality, and I’m passionate about music, cooking, and trying new things. In my tutoring and mentoring, I am patient, adaptable, and committed to meeting the unique needs of each student.

I work as an Engineering Specialist/Consultant, holding:
• Master’s degree in Aeronautical Engineering from Imperial College London,
• AAA* A-Level in Further Maths and Physics,

Having been mentored and tutored myself, I understand the challenges students face. Through my own experiences of overcoming obstacles and achieving success, I’m passionate about helping others do the same. Let’s work together to ensure you reach your full potential, both academically and personally!

Matías

4.64

(25)

Do you want to master the most used design software and bring your ideas to life in 3D? Do not search anymore ! I offer specialized courses to guide you through the exciting worlds of CATIA V5/V6, Inventor, Fusion 360, FreeCAD and 3D printing.

CATIA V5/V6: Discover the design software preferred by engineers for creating complex models and precise assemblies.

Inventor: Dive into the world of mechanical design and learn how to develop innovative products with this powerful software.

Fusion 360: Create organic models, run simulations, and hone your design and engineering skills.

FreeCAD: Explore the basics of parametric design and create 3D models ready for manufacturing.

️ 3D printing: Bring your designs to life! Learn how to use 3D printers, from modeling to concrete production.

Whether you're a beginner or looking to improve your skills, my classes are suitable for all levels. With interactive lessons, hands-on projects, and expert guidance, you'll progress quickly and with confidence.

Don't wait to explore the endless potential of 3D design and 3D printing. Join me on this exciting adventure and start creating your own 3D masterpieces today!

Don't miss this opportunity to develop in-demand skills in 3D design and printing. Join me for enriching and practical lessons you won't forget!

See you soon for our first class together!

Haider

4.64

(25)

Welcome!

I have already completed my master’s degree in mechanical engineering and am currently doing my doctorate.

Tutoring / support is offered in

✔ High school graduation exam preparation
✔ Bachelor's thesis
✔ Master's thesis
✔ Thesis
✔ Project work
✔ Housework
✔ Dissertation
✔ Construction project
✔ Control engineering
✔ Electrical engineering
✔ MS Office applications

+ other subjects on request

When contacting please
Study education
notify!

Jeremy

4.64

(25)

Passionate & empathetic teacher. I have a Master's in Physics with honors from the University of Leicester (which was featured at the time as a top 5 Physics university in the UK by The Guardian) and a - french - European School diploma in which I achieved 90% in Physics and 85% in Maths.

Helping others understand difficult topics and skills is something that I am very passionate about as an empathetic person. I have 6 years of experience teaching Physics and Maths to kids from unprivileged backgrounds both in a homework schools as well as via private teaching. In private teaching, I have experience tutoring people with learning disabilities (ADHD, Dyslexia, Discalculia and more), younger kids of ages 7-12 and older students preparing for their final baccalaureate exams in advanced maths/physics curriculums.

In my classes, I aim to:

- help students achieve better grades in exams/tests in all branches of Physics & Maths
- clearly explain and break down topics
- give context and or example applications of topics (to improve understanding and memorization)
- help with ADHD & other learning disabilities
- give practical advice for university applications (eg. UCAS in the UK) and discuss the exciting Physics research/work and projects you can work on later in life.

Physics has a plethora of useful and fascinating applications, from the detection of Gravitational Waves and Gamma-Ray Bursts to the development of novel Medical Imaging techniques and Nano-technology (eg: smartphones). It is a subject that I am very passionate about and I hope to make use of my years of experience and extensive knowledge to help you understand and love the subject! My lessons will always be tailored to the individual needs of the student, so please do not hesitate to contact me if you have questions!

Adam

4.64

(25)

===================Satisfied or refunded=======================
Hello, I am a doctoral student in electrical engineering and associate professor in engineering sciences, experienced in the field of electrical engineering, I offer courses in engineering sciences (Electronics, automatics, electrical engineering, automation, programming).
Computational Sciences and Technology SNT
IS engineering sciences
Numerical and computer science SNI
Digital electronics
Analog electronic
electromagnetism
Signal processing and data acquisition
Automatic (discrete, continuous)
electrical engineering (transformers, electrical machines, switching power supply)
C/C++ Programming, Assembler, ARM, STM32
renewable energy (wind, PV-solar)
RDM - strength of materials mechanics of solids
Python and SYSML
PIC microcontroller
Microprocessor
MATLAB, proteus
Preparation for competitions
Supervision of graduation projects
CAPLP Electrotechnical and Electronic Electrical Engineering
CAPLP and BTS subjects and answers
Correction caplp 2017 CAPLP 2018 CAPLP 2019 CAPLP 2020
CORRECTION OF BTS TESTS

Samaa

4.64

(25)

With over 4 years of experience I teach math curriculums (GCSE, IGCSE, IB CNISE, SAT) to students from earlier stages, elementary to high school. I focus on all mathematical concepts, develop classroom materials, organize activities, assign homework, grade tests, and prepare students for exams. I prepare mathematics curriculum for my students, like college entrance exams.

I demonstrate excellent mathematics skills and analytical thinking alongside solid instruction. I instruct my students throughout the year and create lesson plans, assign homework, and manage online classrooms. I keep in touch with parents to be aware of the progress.
I hold a Master's degree in Engineering with teacher education courses and I've achieved the highest grades in my math courses throughout the years with straight A Grades.

My Responsibilities towards my students
-Create a great environment that is conducive to learning.
-Care for and effectively assist students with special concerns.
-Analyze data to determine student progress and achievement.
-Work with individual and small groups of students to support mathematics instruction.
-Encourage students who need extra help
-Plan and carry out instructions, activities and prepare learning materials.
-Maintain appropriate records and follow required procedures and practices.
-Work with students to develop and monitor academic goals for both short-term and long-term success.

My qualifications
-Master Degree in Engineering
-An experienced teacher for over 4 years
-Experience with calculus, geometry, statistics, and trigonometry.
-Dedication to instruction of critical thinking and problem-solving with confidence in a collaborative environment.
- Leadership skills and a positive attitude when assisting with decision making.
-Demonstrated professionalism and dedication to continuous improvement.
-Time management skills.

Nicolas

4.64

(25)

As a current Master's student in Aerospace Engineering at TU Delft, I have successfully navigated the entire Bachelor's curriculum and the competitive selection procedure, so I am fully equipped to guide you through the study plan and specific admission requirements. I offer personalized tutoring sessions designed to ensure comprehensive preparation for the entrance exams. These classes include a detailed review of key concepts in Mathematics and Physics, intensive practice with relevant exercises, and specific strategies to tackle the test effectively. I also place a dedicated focus on mastering the First Year Material (FYM) section (often the most challenging and unfamiliar part for applicants) to help you build the confidence and skills necessary to succeed. Furthermore, I am happy to discuss the degree program itself and explore the opportunities available in Delft to help you prepare for your future student life.

Intasar

4.64

(25)

I have graduated with a degree in chemical engineering from the University of Edinburgh, UK. I am also an Erasmus Mundus scholar with a master's in Analytical Chemistry from Uppsala University. Currently, I am pursuing a PhD in physical chemistry.

I have been tutoring since 2012 to fund my education expenses. I formally began tutoring in 2014 as part of my vocational training as a teacher in Ghana, funded by the University of Edinburgh. The formal training has taught me a lot about curriculum development, time management, and fusing my teaching methodology to my students’ needs. I have been tutoring in Physics, Chemistry, and Math, in person and online; the hybrid model has allowed me to reach out and teach students in 8 different countries. I have successful students from these past nine years who have not only commended my work ethic but can also stand testament to my enthusiasm.

My excellent academic career has nurtured in me a natural talent for teaching. My experiences have taught me how to tackle one problem at a time, and I believe that using this approach—paired with my unconventional examples that force students to think outside the box—I can truly provide an excellent understanding and explanation. My teaching methodology is based on two main things: skill development and adaptation. Initially, I create a skeleton of the most suitable methodology tailored to the preferred curriculum, after which, I adapt that lecture to the specific needs of the student based on their knowledge and grasp of the concepts. Second, I like to develop analytical and scientific ability along with knowledge in my students, and for that, I use a combination of resources in the form of worksheets, class tasks, and past papers. Last, I believe in the strong ethic of providing feedback to the parents, so that they are aware of their child’s progress.

Frequently Asked Questions:
Which subject(s) do you teach?
I teach math, mechanics, statistics, chemistry and physics. I also teach biology up to GCSE level.

When are you available? My timetable is quite flexible. I am happy to work weekdays, week evening and weekends.

Which ages and levels do you teach? The majority of my students are between the ages of 10-18, but I also teach college Students. I am also helping foundation and first year university students.

Which qualifications do you prepare your students for? GCSE, o-level, A/S-level, A-level, IB, School entrance exams and SATs

Describe your arrangements for online tutoring? I use Zoom online sessions since it has many tools and features specially designed for interactive and visual learning. I am fully equipped with modern gadgets for e-learning. I use Google drive and docs to share files.

Ammar

4.64

(25)

Engineering and design become much easier when analysis, geometry, technical representation, digital modelling, spatial reasoning, and visual communication are connected within one coherent problem-solving process.

I am a PhD-qualified engineer, university professor, researcher, technical trainer, designer, and multidisciplinary consultant with more than 30 years of experience across engineering, teaching, project work, CAD, technical drawing, 3D modelling, GIS, visualization, information systems, and professional problem solving.

This class provides a personalized pathway for school and university students, engineering and design learners, architects and technicians, researchers, professionals, career changers, and adult learners. Depending on your goals, we can focus deeply on one specialized area or connect several areas within a complete technical workflow.

PHYSICS & APPLIED ENGINEERING SCIENCE
• Mechanics: motion, forces, Newton’s laws, work, energy, momentum, and rotational motion
• Statics, dynamics, equilibrium, torque, and engineering applications
• Fluids, pressure, buoyancy, density, and basic fluid mechanics
• Heat, temperature, thermodynamics, and energy transfer
• Waves, oscillations, sound, optics, electricity, and magnetism according to the learner’s level
• Mathematical modelling of physical systems
• Units, dimensions, vectors, graphs, and interpretation of experimental or engineering data
• Connecting physical principles to engineering design, calculations, and real-world technical problems

CHEMISTRY & ENGINEERING MATERIALS
• Atomic structure, chemical bonding, molecular structure, and periodic trends
• Stoichiometry, chemical reactions, solutions, concentrations, gases, and equilibrium
• Acids, bases, oxidation-reduction, and introductory thermochemistry
• Properties and behaviour of engineering materials
• Metals, polymers, ceramics, composites, and material-selection principles when relevant
• Connecting chemical principles to materials, manufacturing, environmental, and engineering applications

ENGINEERING DESIGN & PROBLEM SOLVING
• Understanding and structuring engineering problems
• Translating requirements into technical objectives
• Identifying constraints, assumptions, variables, and criteria
• Engineering calculations and quantitative reasoning
• Applied mechanics and engineering fundamentals when relevant
• Dimensional reasoning and unit consistency
• Design alternatives and trade-off analysis
• Verification and reasonableness checking
• Engineering decision making
• Design methodology and iterative improvement
• Interpreting technical specifications
• Connecting analysis to drawings, models, and deliverables
• Engineering-management and multidisciplinary project contexts

AUTOCAD & TECHNICAL DRAFTING
• AutoCAD interface and efficient workflows
• Coordinate systems and precise geometric construction
• 2D drafting fundamentals
• Layers, properties, object organization, and standards
• Blocks and reusable drawing content
• Dimensions, annotations, text, and hatching
• Model space and paper space
• Layouts, viewports, scales, and plotting
• Technical drawing principles
• Reading and interpreting engineering drawings
• Plans, sections, elevations, and details
• Drawing organization and documentation quality
• Advanced drafting workflows
• AutoCAD 3D concepts when relevant
• Improving speed, accuracy, and drawing consistency

BIM & REVIT WORKFLOWS
• BIM concepts and model-based thinking
• Revit project organization
• Levels and grids
• Walls, floors, roofs, and building elements
• Doors, windows, components, and families
• Views, sections, elevations, and schedules
• Annotation and documentation workflows
• Sheets and presentation standards
• View templates and graphical consistency
• Family-library organization
• BIM coordination principles
• Connecting models to professional documentation
• Developing structured Revit templates and repeatable workflows

3D MODELLING & PARAMETRIC DESIGN
• 3D geometric thinking
• Curves, surfaces, solids, and meshes
• Constructive and feature-based modelling concepts
• Precision modelling
• Product and engineering geometry
• Architectural and spatial modelling
• Rhino 3D workflows
• Grasshopper and visual parametric thinking
• Parameters, relationships, dependencies, and constraints
• Algorithmic generation of geometry
• Reusable and adaptive design logic
• Design iterations and controlled variation
• SolidWorks and Inventor workflows when relevant
• 3D Studio Max and visualization contexts when relevant
• Connecting models to drawings, analysis, fabrication, or presentation

CAD/CAM & MANUFACTURING WORKFLOWS
• From CAD geometry to manufacturable components
• Design-for-manufacturing principles
• Introduction to CAM concepts and machining strategies
• CNC fundamentals, coordinate systems, tools, operations, and toolpaths when relevant
• SolidWorks CAD/CAM workflows
• Verification, simulation, and interpretation of manufacturing outputs

GIS, MAPPING & SPATIAL ANALYSIS
• Foundations of Geographic Information Systems
• Spatial data models
• Vector and raster concepts
• Coordinate systems and projections
• Georeferencing
• Spatial data collection and organization
• Attribute data and database relationships
• Geodatabases
• Selection and spatial queries
• Buffering, overlay, proximity, and spatial analysis
• Thematic mapping
• Cartographic principles
• Spatial patterns and decision support
• ArcGIS Desktop and ArcGIS Pro workflows when relevant
• Remote-sensing and imagery concepts when relevant
• Integrating maps, analysis, and professional reporting

GRAPHIC DESIGN & VISUAL COMMUNICATION
• Principles of visual communication
• Composition and layout
• Visual hierarchy
• Typography
• Colour and contrast
• Image preparation and editing
• Vector graphics and illustration
• Technical diagrams and infographics
• Maps and spatial presentation
• Engineering and architectural presentation
• Portfolio and project-board development
• Presentation graphics
• Adobe Photoshop workflows
• Adobe Illustrator workflows
• Adobe InDesign workflows
• Connecting technical accuracy with visual clarity

Depending on your objectives, practical work may involve AutoCAD, Revit, BIM workflows, Rhino, Grasshopper, SolidWorks, Inventor, 3ds Max, ArcGIS Desktop, ArcGIS Pro, QGIS, Adobe Photoshop, Illustrator, InDesign, SketchUp, Figma, Canva or other relevant technical and design tools.

My teaching approach follows a structured workflow:
define the problem → understand the requirements → analyze the constraints → develop the geometry or data structure → create the drawing, model, or spatial analysis → verify accuracy → refine the solution → communicate it clearly

I do not simply demonstrate isolated commands. I help you understand why a workflow is appropriate, how information should be structured, how accuracy can be verified, how alternative solutions can be evaluated, and how the final technical idea should be communicated professionally.

We can work with your course syllabus, engineering problem, technical drawing, CAD file, Revit/BIM model, 3D model, parametric definition, GIS dataset, map, design project, portfolio, graphic layout, or professional workflow challenge.

Whether you are learning your first CAD commands, solving an engineering problem, developing a BIM workflow, building a 3D or parametric model, conducting spatial analysis, or improving technical visual communication, I will adapt the sessions to your level, objectives, and pace.

My goal is to help you become an independent technical problem solver who can analyze, design, model, verify, visualize, and communicate solutions with confidence.

Baia

4.64

(25)

I'm a working MEP engineer, currently building Python automation for Revit workflows daily - plan checks, model coordination, and repetitive drafting tasks. I teach other engineers, architects, and BIM professionals how to do the same, using pyRevit and real project workflows, not toy examples.

Topics include:
pyRevit fundamentals and setup
Automating repetitive Revit tasks (model checks, plan generation, data extraction)
Writing custom scripts for your firm's specific workflows
Applying Python automation to real MEP/BIM projects

Alaaeldin

4.64

(25)

Learn PLAXIS 2D & 3D and Geotechnical Engineering with a PhD Researcher in France!

I am a PhD candidate in Geotechnical Engineering at the University of Lille, France, specializing in finite element modelling (FEM), soil–structure interaction, and advanced numerical simulations.

I offer personalized online lessons for civil engineering students, master's and PhD students, researchers, and practicing engineers.

What you can learn:

PLAXIS 2D & 3D
Getting started with PLAXIS and understanding the modelling workflow.
Geometry creation, soil layers, materials, and boundary conditions.
Soil constitutive models and parameter selection.
Mesh generation and staged construction.
Foundation settlement and soil–structure interaction.
Retaining walls, excavations, and underground structures.
Results interpretation and model validation.

Geotechnical Engineering

Soil Mechanics and Foundation Engineering.
Earth pressure and retaining structures.
Settlement and bearing capacity.
Soil–structure interaction.
Personalized Learning

Lessons are adapted to your experience, from beginner to advanced level. We can work through practical examples, discuss theoretical concepts, or review your own numerical models step by step.

My goal is to help you understand both the engineering principles and their practical implementation in numerical modelling software.

Lessons are available online in English, Arabic, or French.

Feel free to contact me to discuss your learning objectives and arrange a personalized lesson!

Hakim

4.64

(25)

Salam i am Hakim I am an engineering student offering practical, personalized online lessons in Languages (Algerian Darija, Tamazight, and French and islamic lessons) as well as STEM subjects (Mathematics, Robotics, and Control Systems).

Whether you want to reconnect with your family roots, prepare for travel to North Africa, master conversational French, or get clear, step-by-step guidance in Mathematics and Robotics engineering concepts, I tailor every lesson to your exact goals.

My teaching style is focused on clarity, practical application, and building your confidence whether we are practicing everyday language dialogues or solving complex engineering problems. Let's work together to achieve your goals

Fariah

4.64

(25)

I make STEM subjects, especially Mathematics and Physics, easier and more enjoyable for students by breaking down difficult concepts into simple, step-by-step explanations. My lessons focus on building a strong understanding of the basics before moving on to more challenging problems.

I use practice exercises, exam-style questions, and real examples to help students apply what they learn and build confidence. With a 730 SAT Math score and a strong academic background in Mathematics and Physics, I can help students improve their problem-solving skills, prepare for exams, and achieve their academic goals.

My teaching approach is patient, interactive, and adapted to each student’s learning pace, so students feel comfortable asking questions and learning from their mistakes.

Turgut

4.64

(25)

This course provides a comprehensive and practical guide to modern engineering, focusing on core concepts such as electromagnetic modelling, RF systems, and sensor technologies. Designed for all skill levels, the course breaks down complex technical phenomena into clear, digestible modules through structured lectures, visual presentations, and step-by-step demonstrations.

You will learn not only theoretical principles but also effective presentation and communication techniques to clearly explain complex technical data, pitch engineering designs, and share project results with multidisciplinary teams. Whether you are building prototypes or presenting technical solutions, this course equips you with both technical expertise and professional communication skills.