Dr. SaMeH S. Ahmed

Associate Prof. of Environmental Engineering

Non-acoustic noise

Non-acoustic noise

Electronic noise and communication channel noise

Electronic noise exists in all circuits and devices as a result of thermal noise, also referred to as Johnson Noise. It is caused by random variations in current or voltage caused by the random movement of charge carriers (usually electrons) carrying the current as they are jolted around by thermal energy. Thermal noise can be reduced by reducing the temperature of the circuit. This phenomenon limits the minimum signal level that any radio receiver can usefully respond to, because there will always be a small but significant amount of thermal noise arising in its input circuits. This is why radio telescopes, which search for very low levels of signal from space, use front-end low-noise amplifier circuits cooled with liquid nitrogen.

There are several other sources of noise in electronic circuits such as shot noise, seen in very low-level signals where the finite number of energy-carrying particles becomes significant, or flicker noise (1/f noise) in semiconductor devices. A digitized and reconstructed analog signal is exposed to additive quantization noise.

In a communication channel, noise is an undesired random signal, often modelled as additive white gaussian noise (AWGN), that may be caused by thermal noise orelectromagnetic interference (EMI) from unknown sources. Noise shold not be confused with crosstalk and other interference from other communication system transmitters. Phaseor frequency modulated communication systems may suffer from phase noise due to synchronization problems and time-invariant channel conditions, caused by mobilityfadingand doppler shift. Deliberate generation of communication system noise and interference is called jamming.

Visual noise

Noise is also present in images. Electronic noise will be present in camera sensors, and the physical size of the grains of film emulsion creates visual noise. This kind of noise is referred to as "grain."

Noise is also used in the creation of 2D and 3D images by computer. Sometimes noise is added to images to hide the sudden transitions inherent in digital representation of color, known as "banding". This adding of noise is referred to as "dithering." Sometimes noise is used to create the subject matter itself. Procedural noise (such as Perlin noise) is often used to create natural-looking variation in computer generated images.

Vibrational noise

The Earth ground and the built environment are subjected to permanent vibrations commonly referred to as seismic noise but nowadays preferably called Ambient Vibrations. These vibrations have natural (ocean waves, wind...) and anthropogenic (traffic, machines...) origins depending on the considered frequency range. These vibrations may be disturbing for people (housing close to railway tracks...) and even cause solidian noise (acoustic noise created by particular vibrations of solids like rooms) but they are also used (recorded) to characterize the structures (civil engineering structure, underground) they are shaking in terms of dynamic properties and eventually physical properties.

Noisy genes

The activity and regulation of our genes are also subject to noise. Transcriptional noise refers to the variability in gene activity between cells in genetically identical populations (even identical twins are non-identical). Noise in gene activity has tremendous consequences on cell behaviour, and must be mitigated or integrated. Noise impacts upon the effectiveness of clinical treatment, with resistance of bacteria to antibiotics demonstrably caused by non-genetic differences. Variability in gene expression may also contribute to resistance of sub-populations of cancer cells to chemotherapy. In certain contexts, such as the survival of microbes in rapidly changing stressful environments, or several types of scattered differentiation, noise may be essential.

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For CE 370 students : I do apologize for did not attend the extra lab session that proposed to be on Wednesday at 6 am.  Sorry

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Mining Engineering

Mining engineering is an engineering discipline that involves practice, theory, science, technology, and the application of extracting and processing minerals from a naturally occurring environment. Mining engineering also includes processing minerals for additional value.

Environmental Engineering

Environmental engineers are the technical professionals who identify and design solutions for    environmental problems. Environmental engineers provide safe drinking water, treat and properly dispose of wastes, maintain air quality, control water pollution, and remediate sites contaminated due to spills or improper disposal of hazardous substances. They monitor the quality of the air, water, and land. And, they develop new and improved means to protect the environment.


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Universities I've worked in

Assuit University (Home University), Egypt

Imperial College, London, UK

Faculty of Engineering, Al-Mergeb University, Libya

King Saud University, KSA

,Majmaah University

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Course 2016/17-1

  1. Computer Applications in Surveying  CE 473
  2. Surveying 1 CE 370
  3. Photogrammetry CE 474
  4. Surveying II  CE 371
  5. Design I  (round 4) CE 498

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Member of the Editorial Board: " Journal of Water Resources and Ocean Sciences"  2013


Participating in The Third International Conference on Water, Energy and Environment,(ICWEE) 2015 - American University of Sharjah, UAE 24-26 March 2015 with a Paper and Poster

New article

Recovery of Titania from Waste-Sludge of Majmaah Water Treatment Plant

"Production of Titania Nano-particles from Wast-


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Results of M2 CE311

Student Conference

Participation  in the 6Th Student Conference

With a paper and oral presentation

From the Senior Design Project CE499 -35

See inside, the paper, and presentation

CE 370 Course

Surveying  I -  CE 370 - 2016-2017-1

Power point


Lecture notes

Second Midterm Exam


Model Answer
Inside, please follow:

Student Performance Records

CE 371 Course

Surveying II - CE 371 - 2016-2017-1


First midterm exam



See Inside

Student Performance Records

CE473 Course

Computer Applications in Surveying

CE 473


Power point


Exams + Quizzes


CE 474 Course

2015-2016-2 - Photogrammetry  CE474

Available 0-1-2-3-4 Power point


Quizzes 2 and 3 with model Answer

Available Chapter 1,2,3,4,5 Lecture notes

Report 1  Cameras Report


60 marks Exams

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Student Performance Records

CE 360 Course

Environmental Engineering 1

CE 360: Environmental Engineering 1


Y PP0-1-2-3,4 Power point
Y 1,2,3,4,5 Chapters

Water quality Poster + Climate Change Reports
will be announced (Quiz #2 will be using D2L- Online Quizzes


Quizzez 2,3 and 4 with model answer and results Exams and results

GE 306 Course

Engineering Report Writing

GE 306: Engineering Report Writing

CE 499 Course

Senior Design 2 - CE 499

Meeting on 14-4-2015

Second Best paper from Senior Design Projects in 2015

Paper title:

Evaluation of Groundwater Quality Parameters using Multivariate Statistics- a case Study of Majmaah, KSA


Abdullah A. Alzeer

Husam K. Almubark

Maijd M. Almotairi

CE 360-Summer Course

Environmental Engineering I

Welcome to CE360 second Term 2015-2016 

Engineering Practice

 Engineering Practice GE 307

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Civil and Environmental Engineering Department
College of Engineering, Majmaah University
Majmaah, P.O. 66, 11952, KSA

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Your frequent visit to my website has helped  a lot to get the 2nd place in the university competition in the  year 1434-2013... Thanks very mush and please keep following my work

زيارتكم المتكررة لموقعي ساهمت في حصولي على المركز الثاني لاحسن المواقع الشخصية بجامعة المجمعة ...لكم جميعا خالص شكري وتقديري

CE 212 - Summer Course

Properties and Strength of Materials 1

CE 212

Y from PP0 to PP 6 + PDF Power points
Y Midterm #2 + Model Answer + results Exams
Y lab 3 Labs

Solution of Quiz 4 + Results HW

CE 311- Summer Course

Soil Mechanics and Foundation Engineering

CE 311

M2+ model Answer + PP 1-9 = PDF 1-9 all are available

Sheets 2 + 4 with model Answers

Results of M2

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