Author Archives: Scientific Market

About Scientific Market

I'm mechanical engineer graduated on 1998. I'm programmer for more than 20 years in (C series and others, VBA, JAVA, Autolisp, SQL...). Expert in physics and science.


For full subject and images refer to

Car history

Car essential component

Modern car technology

Car safety systems

Car capability (Load, speed, off-road, durability…)

Intelligent / computerized car systems

Car selection


This document lead us to understand the main parts of a car without entering in details (except following the references or the links)

Car history

The history of the automobile begins as early as 1769, with the creation of steam engined automobiles capable of human transport.[1] In 1806, the first cars powered by an internal combustion engine running on fuel gas appeared, which led to the introduction in 1885 of the ubiquitous modern gasoline- or petrol-fueled internal combustion engine.

The year 1886 is regarded the year of birth of the modern automobile – with the Benz Patent-Motorwagen, by German inventor Carl Benz.

Cars powered by electric power briefly appeared at the turn of the 20th century, but largely disappeared from use until the turn of the 21st century. The early history of the automobile can be divided into a number of eras, based on the prevalent means of propulsion.

                         Reference and for further reading:

Car essential component

Car body

Car motor

Car motion transmission  / differential

Car Chock absorber system / suspension system

Exhaust system

Car body




The car body is designed to protect the passenger inside, reduce aerodynamic effect or air drag force, beautiful and exiting shape.  The car body shape also take into consideration the car shock or accident add try to distribute the shock force to the metallic body instead to hurt the passenger. Also nowadays also the companies are designing their cars by let the motor take also the shock and this protects the passenger.


Car Motor

Car motor is the part which creates force to move the car using reserved energy in a special reservoir. The first motors were working using water steam and its reservoir is water and fuel (such wood, charcoal, and diesel). Second generation is an engine working on fuel such benzene, diesel, fuel oil type 2 or gas. And the last one is electrical motor using electricity reserved in batteries.

The problem with the electrical motor is the low acceleration of the vehicle working on. The resent vehicle using a combined system named hybrid which is an engine using liquid fuel (or gas) and electrical motor when the high acceleration is not needed (usually this is an economical system in a high traffic city, or in horizontal road where no need for high speed).

Some cars have its motor in front of it and some at rear and both have its advantage and disadvantage.

Now we will see a fast description of each motor type.

Benzene or gasoline engine


Benzene engines are the most fastest engine cycle (rpm) due to fast explosion of the benzene, as the octane number is high the more and fast power produced (for the same motor system).

There are many types of benzene engine:

Straight cylinders movement

The cylinders of a car engine are arranged in two different ways: Inline (one row) or “V” (two rows side-by-side that form a “V” shape).

Cylinders engine may contain 3(special),4,6,8 or 12 cylinders with 16 and 24 valves (nowadays) Otto cycle.

For more:


Rotary engine

The rotary engine usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary and the entire cylinder block rotated around it.

This type of motor used by few cars manufactures and still has problems.


SOHC Engines and DOHC Engines

SOHC stands for Single Overhead Camshaft. That means that there is only one camshaft per header. Inline engines will contain one camshaft. V-type and/or flat will contain 2 camshafts. For a SOHC engine there are usually 2 valves per cylinder but there can be more with the addition of cams for each valve.

DOHC stands for Double Overhead Camshaft. Now there are 2 camshafts per header. So in an inline there are 2 camshafts because there is only one header, but there are 4 in a V-type or flat engine. These DOHC engines usually have 4 valves by cylinder. One camshaft for the exhaust valves and the other is for the intake valves.

Advantages to having a DOHC engine over a SOHC is that the engine has twice as many intake and exhaust valves as a SOHC motor. This makes the engine run cooler and more smoothly, quietly, and efficiently. But the downfall is that DOHC engines cost more for repairs. To ensure against expensive engine repairs, make sure you change your engine’s timing belt about every 60,000 miles.

Additional Valves
There are some other valve combinations as well. Some engines, like the D15 in a Civic and the C30 in an Accord, have 4 valves per cylinder but are SOHC engines. This means there are four lobes on one camshaft per cylinder. With four lobes, or cams, per cylinder, they become smaller and wear easier which is a draw back to this setup. With one camshaft though, this will make the car lighter which creates better performance.

Another variation is 5 valves per cylinder developed mostly in newer Audi’s. There are 3 cams on one camshaft and 2 on the other. The set with 2 cams runs 2 valves that are used for exhaust and the 3 on the other camshaft are used for the intake. Cars with 5 valves tend to be quieter and have better performance. Although if something goes wrong it can be costly to fix because parts are harder to find and more expensive.

VTEC Engines

The VTEC(Variable Valve Timing and Lift Electronic Control) systems fixes these problems. It is a system that changes the properties of the valves to fit the RPM. When at a lower RPM it uses 2 smaller cams on the camshaft to push the valves open and closed. This allows for less overlapping of the exhaust and intake valves. They open at a smaller height for a shorter time. When at around 6000 rpm, it switches to one large cam in the middle of the other 2, this single cam pushes both valves. The larger cam pushes the valves farther and for a longer time period, overlapping occurs between exhaust closing and intake opening, which allows more air to enter the cylinder creating more power at a higher RPM. This system makes it possible to get more power at all RPMs. The Vtec system also provides better fuel economy, and lower emissions.


Acura’s VTEC Engines
In normal engines the valves that supply the engine with air and fuel open and close at the same rate, the same distance, and the same length of time at all rpm. The problem is that the car will need air quicker at high rpms. An overlap of exhaust valves closing and intake valves open also helps by providing a suction. This suction brings intake air in faster.

Cars that are designed for speed need to be most efficient at high rpms. At higher speeds more power is require accelerating 1 km /h or mph then at lower speeds. This being said, a sporty car or race car needs more power at the high end rpms to increase its speed quicker.

Note: Regular driving cars lack power at both high and low rpm but work efficiently at mid range rpm.

VVT and VVT-i

VVT is Variable Valve Timing and VVT- intake.

The ‘intake’ or ‘intelligence’ valves vary at all RPMs using the feedback from o2 sensors, air flow sensors, etc… So you will get slight improvement across the whole power band (or rpm band).

VTEC is either ‘on’ or ‘off’. It doesn’t continuously change like VVT-i.

Dual VVT or VVT-i

The Dual VVT-i system adjusts timing on both intake and exhaust camshafts.


The ignition type of an engine relates to how the fuel is ignited inside the engine. The fuel is either spark-ignited with a spark plug or compression-ignited by compressing air until the temperature reaches ignition. Gasoline engines use spark ignition while diesel engines are compression-ignited.


Without a cooling system, car engines will quickly destroy themselves due to extreme temperatures. Car engines are either liquid- or air-cooled. Liquid-cooled engines are the modern industry standard and are cooled by a water pump that circulates water throughout the engine.

Read more:

Read more:

For more engine type check:

Diesel engine

Rotary engine


Car motion transmission / differential


Car transmission / Car gearbox / lever / transmission axle


Car transmission box is a gear box which transmits car motor / engine motion to transmission shaft then to the wheels.

Transmission type is divided into two types, Manual and automatic, which (the automatic) divided into semi-automatic, full automatic and tiptronic.

The gear box comprise, clutch axle where a group of different size of gears are fixed on.

The different size of gears / cogs when engage let the transmission axle rotate in difference speed. All are related to gears diameter (teeth number)

When the gear box hand lever changed to another position, a group of gears will be separated from group to join to another, and changing the gears diameters ratio will lead to change the axle rotation speed, and in order change the transmitted torque also (Car Torque, is the power which let the car to climb or get more force in motion). Reducing the speed lead to increase the torque and vice versa. The 4×4 or SUV need a high torque for off-road driving. And a big difference in gears diameter ration lead to increase the speed with less force; this is happen on horizontal highway (speed 5 or 6) and this reduce the fuel consumption. When moving off from rest you need lots of torque.


Manual gearbox / transmission


The manual gearbox need the driver to change by hand the lever to switch to another speed, or rear motion or even to free or dead point (no force is transmitted from the motor to the transmission axle or wheels).

Automatic transmission


The automatic transmission let the gearbox work by itself (it has additional type of gears called female gears and arranged like planets around the sun, called planet gears). Each time the force (torque) applied on the transmission axle this let a gear to jump automatically to another position and then in order the axle rotation will be changed to accommodate the applied torque.



Tiptronic change the speed lever by shift from one to another by applying + and – .


CVT Automatic transmission

Continuously variable transmission (CVT) gearboxes dispense with traditional gears in favour of a special steel belt (or chain) running between two sets of interlocking cones. This gives an infinite variability between the highest and lowest gears with no discrete steps or shifts (The cone allow that).

For more transmission type check:

Manual transmission






Gearbox operation



Car Chock absorber system

A car shock absorber is a mechanical device which can absorb or damp a vertical shock or impulse. It transforms the mechanical shock to heat (thermal energy). The vehicle suspended on those dampers which are related to or separate the car body from the car wheels axles. The shock dampers are the principal part of the car suspension system.

A shock absorber using only a spring can’t be used alone, because it is oscillate up and down. A hydraulic damper (using oil, moving up and down through small holes) damp the spring motion in few cycles (The oscillation terminate after few up and down with decreasing the amplitude of moving up and down).

The principal types are exist, spring-hydraulic piston or pneumatic piston (air instead of oil) and metallic bridges called leaf spring for SUV or trucks.

There are many types for the car suspension system. Price has a wide range from Cheap to 10000$ for only the suspension system. The suspension system is very important, it improve the ride quality over rough ground or off-road or road holes / cavities. The good suspension system also can protect car parts from bad or heavy vibration. Also a good tire quality and appropriate pressure can absorb a wide range of vibrations band.







For more:


Leaf spring

Three   quarter-elliptic        



McPherson struts

The MacPherson strut is a type of car suspension system which uses the axis of a telescopic damper as the upper steering pivot. It is widely used in modern vehicles and named after Earle S. MacPherson, who developed the design. (Ref. Wikipedia)



A simple MacPherson strut suspension on the left front wheel of a rear-wheel drive vehicle. Front of the vehicle top right in image.
Red: Steering knuckle or hub carrier
Blue: Lower control arm or track control arm
Light blue: Steering gear tie rod
Lower purple: Radius rod
Upper purple: Coil spring
Yellow: Tubular housing containing shock absorber or damper


MacPherson struts consist of a wishbone or a substantial compression link stabilized by a secondary link which provides a bottom mounting point for the hub or axle of the wheel. This lower arm system provides both lateral and longitudinal location of the wheel. The upper part of the hub is rigidly fixed to the inner part of the strut proper, the outer part of which extends upwards directly to a mounting in the body shell of the vehicle.

To be really successful, the MacPherson strut required the introduction of unibody (or monocoque) construction, because it needs a substantial vertical space and a strong top mount, which unibodies can provide, while benefiting them by distributing stresses.[4] The strut will usually carry both the coil spring on which the body is suspended and the shock absorber, which is usually in the form of a cartridge mounted within the strut (see coilover). The strut also usually has a steering arm built into the lower inner portion. The whole assembly is very simple and can be preassembled into a unit; also by eliminating the upper control arm, it allows for more width in the engine compartment, which is useful for smaller cars, particularly with transverse-mounted engines such as most front wheel drive vehicles have. It can be further simplified, if needed, by substituting an anti-roll bar (torsion bar) for the radius arm.

Advantages and disadvantages

Although it is a popular choice, due to its simplicity and low manufacturing cost, the design has a few disadvantages in the quality of ride and the handling of the car. Geometric analysis shows it cannot allow vertical movement of the wheel without some degree of either camber angle change




, sideways movement, or both. It is not generally considered to give as good handling as a double wishbone or multi-link suspension, because it allows the engineers less freedom to choose camber change and roll center.

Another drawback is that it tends to transmit noise and vibration from the road directly into the body shell, giving higher noise levels and a “harsh” feeling to the ride compared with double wishbones[citation needed], requiring manufacturers to add extra noise reduction or cancellation and isolation mechanisms.

Despite these drawbacks, the MacPherson strut setup is still used on high performance cars such as the Porsche 911, several Mercedes-Benz models and lower BMWs models (including the new Mini but excluding the 2007 X5,[6] 2009 7-series, 2011 5-series and 5-series GT).

The Porsche 911 up until the 1989 model year (964) use MacPherson strut designs that do not have coil springs, using a torsion bar suspension instead. Also like a modern car Honda, Hyundai, Kia and others.


Short Long Arms suspension (SLA)

A short long arms suspension (SLA) is also known as an unequal length double wishbone suspension. The upper arm is typically an A-arm, and is shorter than the lower link, which is an A-arm or an L-arm, or sometimes a pair of tension/compression arms. In the latter case the suspension can be called a multi-link, or dual ball joint suspension.

The four-bar link mechanism formed by the unequal arm lengths causes a change in the camber of the vehicle as it rolls, which helps to keep the contact patch square on the ground, increasing the ultimate cornering capacity of the vehicle. It also reduces the wear of the outer edge of the tire.

SLAs can be classified as short spindle, in which the upper ball joint on the spindle is inside the wheel, or long spindle, in which the spindle tucks around the tire and the upper ball joint sits above the tire.


Short spindle SLAs tend to require stiffer bushings at the body, as the braking and cornering forces are higher. Also they tend to have poorer kingpin geometry, due to the difficulty of packaging the upper ball joint and the brakes inside the wheel.

Long spindle SLAs tend to have better kingpin geometry, but the proximity of the spindle to the tire restricts fitting oversized tires, or snowchains. The location of the upper balljoint may have styling implications in the design of the sheetmetal above it.

SLAs require some care when setting up their Bump Steer characteristic, as it is easy to end up with excessive, or curved, bump steer curves.


Comparison between SLA and McPherson struts

As per above and for more stability car the SLA is better than MCPheron struts suspension system.

Active  suspension / Active Body Control

The active suspension and adaptive suspension/semi-active suspension are types of automotive suspensions that controls the vertical movement of the wheels with an onboard system, rather than in passive suspensions where the movement is being determined entirely by the road surface .Active suspensions can be generally divided into two main classes: pure active suspensions and adaptive/semi-active suspensions. While adaptive suspensions only vary shock absorber firmness to match changing road or dynamic conditions, active suspensions uses some type of actuator to literally raise and lower the chassis independently at each wheel (Active Body Control, ABC).

These technologies allows car manufacturers to achieve a greater degree of ride quality and car handling by keeping the tires perpendicular to the road in corners, allowing better traction and control. An onboard computer detects body movement from sensors throughout the vehicle and, using data calculated by opportune control techniques, controls the action of the active and semi-active suspensions. The system virtually eliminates body roll and pitch variation in many driving situations including cornering, accelerating, and braking.

This type is expensive comparing to the LSA and McPherson type. This type is used by Mercedes-Benz, BMW, Infinity Q45, Toyota Soarer.



Adaptive/semi-active systems can only change the viscous damping coefficient of the shock absorber, and do not add energy to the suspension system. Though limited in their intervention (for example, the control force can never have different direction than the current vector of velocity of the suspension), semi-active suspensions are less expensive to design and consume far less energy. In recent times, research in semi-active suspensions has continued to advance with respect to their capabilities, narrowing the gap between semi-active and fully active suspension systems.


Used by Mitsubishi Galant, Citoen XM.

Electronically Modulated Suspension

Used by Toyota.

Hydraulic actuated

Hydraulically actuated suspensions are controlled with the use of hydraulic servomechanisms. The hydraulic pressure to the servos is supplied by a high pressure radial piston hydraulic pump. Sensors continually monitor body movement and vehicle ride level, constantly supplying the computer with new data. As the computer receives and processes data, it operates the hydraulic servos, mounted beside each wheel. Almost instantly, the servo-regulated suspension generates counter forces to body lean, dive, and squat during driving maneuvers.

In practice, the system has always incorporated the desirable self-levelling suspension and height adjustable suspension features, with the latter now tied to vehicle speed for improved aerodynamic performance, as the vehicle lowers itself at high speed.

Electromagnetic recuperative

This type of active suspension uses linear electromagnetic motors attached to each wheel. It provides extremely fast response, and allows regeneration of power consumed by utilizing the motors as generators. This nearly surmounts the issues of slow response times and high power consumption of hydraulic systems.

Used by Audi

Magneto rheological damper

Another fairly recent method incorporates magneto rheological dampers with a brand name MagneRide. It was initially developed by Delphi Corporation for GM and was standard, as many other new technologies, for Cadillac Seville STS (from model 2002), and on some other GM models from 2003. This was an upgrade for semi-active systems (“automatic road-sensing suspensions”) used in upscale GM vehicles for decades. It allows, together with faster modern computers, changing the stiffness of all wheel suspensions independently. This type used in mostly expensive vehicles. the damper fluid contains metallic particles. Through the onboard computer, the dampers’ compliance characteristics are controlled by an electromagnet. Essentially, increasing the current flow into the damper raises the compression/rebound rates, while a decrease softens the effect of the dampers. Information from wheel sensors (about suspension extension), steering, acceleration sensors and some others is used to calculate the optimized stiffness. The fast reaction of the system allows, for instance, make softer passing by a single wheel over a bump in the road.


Exhaust system





Exhaust system



الهاتف المحمول – الخليوي

الهاتف المحمول أو الخليوي

Arabic    English

هدف العرض

  1. ما هي الأجهزة الخليوية الذكيّة
  2. الأجزاء الأساسيّة في التلفونات الذكيّة
  3. كيف تختار جهلزك المحمول
  4. ما هو المخمد الإلكتروني أو الباد

فهم التلفونات المحمولة الذكيّة

التلفونات الذكيّة هي تلفونات محمولة يشغلها نظام خاص بها. وتسمى هذه التلفونات بالذكيّة لأنها تحتوي على 10 الى 15 جهاز صغير حساس للتأثيرات المحيطة به وتدعى بالحساسات أو الاستشعاريات لهذه التأثيرات. بالإضافة الى أنه يمكنه فتح البرامج التطبيقيّة. الحساسات يمكنها استشعار والتقاط المعلومات المحيطة بالجهاز التي تساعد المستخدم على تحديد موقعه بالأبعاد الثلاثيّة، سرعته، قوة أو لمعان الإضاءة، قوة الضجيج، الحقل المغنطيسي ومنها التابع للأرض، يكشف المعادن، الضغط الجوي، حرارة البطاريّة أو المحيطة بالجهاز، يأخذ الصور (كاميرا) يتصل بالأنترنت …الخ. يمكنه تشغيل واسع من الأدوات (تماما مثلما يقم به الكومبيوتر ولكن بمقدرة محدودة). إذاً التلفونات الخليوية الذكيّة هو جهاز واحد يعادل عدة أجهزة: تلفون محمول، وعدة أجهزة لديها استعارات، قاموس بكل اللغات، دفتر للملاحظات اليوميّة، أجهزة الصوت وتسجيله، راديو، وقد يحتوي البعض على جهاز تلفزيوني، وجهاز التحكم بالتلفزيون المطابق لجهاز التلفزيون، والبعض منها يحتوي على قلم للكتابة عليه الكترونياً وكاميرا للصور الثابتة والمتحركة، ولكن بمقدرة محدودة من حيث دقة التفاصيل ووضوح الصورة وهذا يتعلق ب عدد البيكسلز pixels  ومسافة البؤرة focal distance or range ،

يتضمن أيضا على شتى أنواع الات الحاسبة، ومنظمات المواعيد وعدد كبير من المعلومات المتعلقة بالأشخاص وكيفية الإتصال بهم، أيضا يحتوي الجهاز على مصباح كهربائي. أيضا يمكن إستعماله كجهاز للألعاب وذاكرة لنقل المعلومات… وأيضا برامج للتواصل الاجتماعين، للهندسة من الرسم الى الحسابات، وبرامج تستعمل عادتا على نظام الميكروسوفت   و أبل. كما يمكنه الإتصال بالأنترنت لقراءة الصحف والمجلات والكتب. كما يمكنك الشراء من خلال الإتصال بالأنترنت. من الجيل الثالث والرابع (سرعة الإتصال) وأيضا يمكن إستعمال الواي فاي.

المكونات الأساسية في الأجهزة الذكيّة

  1. شاشة تتلقى الأوامر عن طريق اللمس بقراءة موقع اللمس وهذا من خلال رسم بياني، كما لها عدة أحجام.
  2. هوائي يلتقط ويبث موجات كهرمغنطيسيّة بين 1850 و 1900 مليون (ميغا) هرتز بقوة 1.2 و 1.8 واط. هذه الموجة تحما المخابرة الصوتيّة والرسائل والأنترنت.
  3. هوائي الواي-فاي ليلتقط ويبث المعلومات من والى المودم (المغير والمستخلص) والروتر (جهاز التوجيه) منها للأنترنت على الموجة 2.4 غيغا هرتز عادتا.
  4. بلوتوس لربط خليوي مع أخر بدون أشرطة كهربائية ويستعمل لنقل المعلومات مثل النصوص , الصور والأفلام.  للمزيد
  5. سبيو (وحدة المعالجة المركزيّة) والذاكرة. الذاكرة تنقسم الى قسمين، قسم لنظام التشغيل وقسم لتخذين المعلومات. أو لنقلها عبر توصيلة يوأسبي وذاكرة أخرى تدعى شريحة أسدي  ويمكن ذيادتها لاحقا. سرعة سبيو تؤثر على أداء الخليوي. وحيث لدينا سرعات كبيرة للوحدة المعالجة، فتؤهل النظام بتشغيل عدة برامج دفعة واحدة. سرعة السيبيو والذاكرة رام تقاس بالتردد الكهربائي وهو الهرتز أي دورة في الثانية. مثلا حديثا تفوق السرعات الواحد مليار هرتز بالثانية. ويمكنها نقل 32 معلومة جزئية في كل دورة أو هرتز.
  6. البطارية، وهي مصنوعة من جزيئات الليثيوم وبعض المواد الأخرى. تقاس سعتها ب ملي أمبر ساعة أي في أجزاء من الألف من الأمبر خلال فترة ساعة كاملة. للمزيد…
  7. بطاقة السيم (وحدة تعريف المشترك) التي تسمح لك بالإتصال بالشركة الخليوي لتقم باتصالك والخدمات الباقية. للمزيد
  8. شاحن البطارية، يوجد بعدة أنواع، منها يستعمل في المقبص الكهربائي 110 أو 220 فولت، ومنها في يوأسبي تشحن من الكومبيوتر أو أي جهاز لديه باب لل يوأسبي وأيضا شاحن يستعمل في السيارة.
  9. أخيراً الحساسات أو الإستشعارات (ليس كل الخلويات لديها كل الإستشعارات وهذا حسب سعرها) :
  10. جهاز قياس التسارعات: وهو قياس تسارع التلفون في كل الاتجاهات مع إضافة تسارع الموجود من خلال جاذبية الأرض
  11. جهاز قياس الجاذبية: يقيس قوة جاذبية الأرض على الخليوي. وعادتا هي 9.8 متر / ثانية2
  12. جهاز لقياس تغيير الإتجاه ويدعى جيروسكوب، يقيس سرعة التغيير بالدرجة أو الراديون.
  13. لقياس شدة الاستطاعة الضوئية أو كثافة الضوء بوحدة القياس لوكس. مثلا المكتب يحتاج الى 250 لوكس. الإنسان يبدأ الرؤية من لوكس صفر أو 1 حسب حساسية العين للشخص. ، الشمس في وضح النهار تعطي بين 600 و  1000 لوكس. أيضا هذا الحساس يزيد خيارات على جهازك بمعرفة وجود الضوء أو عدمه، يسكت الصوت عند إدارة جهازك الى الطاولة أو الظلام عندما يرن، أو إذا كان جهازك في الظلام (حقيبة مثلا) وباستعانة بحساس لكشف الأشياء يمكن تضخيم صوت الهاتف عندما يرن لتسمعه. وأي فكرة تتعلق بهذا.
  14. حساس التسارع الطولي، وهو لقياس التسارع لجهازك ولكن يزيل تأثير الجاذبية ولا تدخل في الحساب.
  15. حساس لقياس حقل المغنطيسي المحيط بالجهاز في الميكرو تسلا، وهذا يساعد على تحديد القطب المغنطيسي للأرض ومنها أي إتجاه أخر. أيضا يساعد على تحديد أي حقل مغنطيسي ناتج عن حجر المغنطيس، الكهرباء وحتى المعادن مثل الحديد العادي أو أي معدن يتأثر بالحقل المغنطيسي وأحيانا يدعى بكاشف المعادن. وهذا أيضا يساعد على تحديد الأساطل في الحيطان أو الأرض وأيضا حتى قضبان الحديد الموجودة في العواميد الإسمنتيّة.
  16. ميكروفون أو المذياع، هو جهاز للالتقاط الأصوات للتكلم عبر الهاتف أو تسجيل الأصوات من خلاله. أيضا يمكن له قياس شدة الصوت بالدسيبل. والإنسان يبداء بسماع الأصوات من أكبر من صفر ديسيبل. مثلا في الاستديوهات لتسجيل الأغاني يتطلب ضجيج ما تحت 20 ديسيبل. التكلم العادي  يصدر أصوات ما بين 40 و 60 ديسيبل. 60 ديسيبل يعتبر ضجيج عالى. محركات الطائرة تصدر ضجيج ما بين 80 و 90 ديسيبل والصاروخ عند إطلاقه 120 ديسيبل. الديسيبل هو مقيلاس الضغط الذي يصدره الصوت بمقياس لوغاريتميك. مثلا صوت يزيد 1 ديسيبل على صوت أخر يعني أنه أقوى منه ب 10 مرات وإذا ب 2 فيكون بمئة مرة. والإنسان يمكنه تمييز تغيير الصوت عندما يختلف ب 3 ديسيبل وأيضا إذا تغير بواحد ولكن بصعوبة.
  17. المتحدث أو مكبر الصوت:  وهو يخرج صوت المتحدث أو الموسيقى أو أي صوت من المحمول.
  18. حساس الإتجاه: وهو يعتمد على الحقل المغنطيسي للأرض أو الحاصل (المجموع) للحقول المغنطيسية ويحدد إتجاه واحد وعادتا يكون بنسبة كبيرة يدل على شمال الأرض المغنطيسي، تماما مثل البوصلة.
  19. حساس لقياس الضغط الجوي بالميلي بار أو ملي باسكال. الضغط الجوي العادي يعادل 101325 باسكال.ضغط 10 باسكال يعادل 1 كلغ بكل متر مربع. ودقة هذا الجهاز أو الحساس ليس لها قيمة ما دون الواحد باسكال لأنه يتغير بسرعة لأي شيء يحيطه. كلما ارتفع الضغط كلما ارتفعت الحرارة والعكس يعني البرودة. ولكن هذه المعادلة ليست ثابة أو صحيحة دائما. لأيضا يتغير الضغط حسب الارتفاع ويكون 10 باسكال لكل 100 متر (طبعا هذا يتغير لعدة عوامل).
  20. حساس لأشياء القريبة ويدعى بروكسيميتي سانسر. هذا الجهاز عادتا يكشف أن جسما ما مر من أمامه وعادتا يلتقط حتى 5 سنتمتر في أجهزة الخليوية. وهذا يساعد على بعض العمليات التلقائية ألأتوماتيكية من حيث تدوير الشاشة، أو تخفيض الصوت أو زيادته أو أي عمل ممكن أن يستفيد من هذا الجهاز.
  21. حساس الحرارة وهو لقياس الحرارة المجاورة وعادتا البطارية تؤثر عليه وبالأخص إذا كان الجهاز ساخن من جراء فترة طويلة من التشغيل.
  22. حساس أو جهاز لقياس نسبة الرطوبة النسبية وتحت 40 يكون الهواء ناشف وفوق ال 70 يكون رطب.

نظام التشغيل للتلفونات المحمولة

كل تلفون ممكن أن يحتوي على نظام تشغيل خاص بالشركة المصنعة أو على نظام موحد لشركة أخرة تماما مثل الحاسوب أو الكومبيوتر. ا هم الأجهزة هي:

Nokia, Motorola, Sony-Ericson, Sony, LG, iPhone, Samsung, blackberry, HTC, Microsoft… (latest number is 83 cell phone manufacture) for more….

بعد إطلاق نظام أندرويد كل القصة قد تغييرة وبدأ شركة الميكروسوفت بإصدار نظام الويندوز للمحمولات الخليوية. كما شركة أبل لها نظامها الخاص لل أي فون والأن الأكثر شيوعا هو نظام الأيندرويد والأيفون. اليك بالإنكلزية الأنظمة المشغلة:

The OS are: Android, Apple iOS, Symbian, Blackberry OS, BlackBerry playbook OS , WebOS, Bada OS, Windows Mobile, Windows Phone OS, and MeeGo OS. for more details…

كيف تختار جهازك المحمول

يجب أن تنتبه الى بعض النقاط المهمة أو المواصفات قبل شرائك الجهاز الخليوي.

أولا هل تهتم للسرعة؟ إذا يجب أخذ بعين الاعتبار سرعة الوحدة المركزية سي بي يو (بال غيغا هرتز)  ومودله وسعة الذاكرة ونظام التشغيل. والأهم هو نظام التشغيل. في الأسواق الأن أشهر نظامين الأبل والأندريود وهذا الأخير هو أبطئ بشكل ملحوظ. من الأيفون أو نظام أبل. كلما كثرة المعلومات المخزنة كلما أصبح نظام أندرويد أبطئ. في الأسواق هناك برامج تسرع قليلا الجهاز (بنسبة 30%) ولكن يبقى رغم هذا النظام بطئ بنسبة 50 الى 100% من الوقة الذي يحتاجه الأيفون وأحيانا أكثر. ولا تنسى كلما زادة المعلومات بطؤ النظام أكثر. لأن النظام يريد تحويل البرنامج المراد تشغيله من الاينكس الى لغة الألة، أما الأبل محول تلقائيا الى لغة الألة.

ثانيا إذا كنت مهتم لتخذين معلومات كثيرة يجب التأكد إذا بإمكانك زيادتها، وحسب يومنا هذا نظام أبل لا يسمح أما نظام أندرويد يسمح. بذلك، ولكنه يحتاج الى ذاكرة أكبر للتشغيل وبالأخص عند إستعمال عدة برامج في نفس الوقت الذي يمييز الأندرويد به، ولكن حتى الأن الأيفون لا يستعمل تلك التقنية بشكل أساسي، ولكن رأي الخاص هذا ليس مهم فالأفضل هي السرعة و زيادة الذاكرة ويبقى الخيار غير نهائي لوجود السرعة في الأخر والذاكرة في الثاني.

ثالثا في نظام أبل لا يمكنك نقل المعلومات عبر يو أس بي ولكن تحتاج الى برنامج خاص وهذا أيضا مستعمل في نظام الويندوز، ولكن عند أندرويد يمكنك هذا ويكون تلفونك المحمول وسيلة سهلة لنقل المعلومات.

رابعا تأكد إذا كنت بحاجة الى نوعية جيدة من الأفلام والأصوات وهذا موجود في معظم التلفونات الذكية.

خامسا ما هي الحساسات أو الاستشعارات التي تريدها وهذا حسب الجهاز الذي تريد شرائه وكلما زادة زاد السعر.

سادسا حجم شاشة العرض للأفلام، برامج الهندسة …الخ ولكن وضعه في الجيب يكون أصعب وحمله غير سهل وأيضا سعره أغلا من جهاز مطابق ولكن بشاشة أصغر.

سابعا: هل تهتم للبرامج المجانيّة أو المدفوعة. أسواق الأندرويد أسواق مفتوحة وفيها نسبة أكبر مجاني مقارنتا مع نظام أبل ولكن برامج الأندرويد فيها نسبة أكبر غير ثابة مقارنتا مع أبل أو غير نظام بسبب أي شخص يمكنه برمجة أي برنامج وعرضه على الأنترنت ويمكن أن يكون فيه بعض المشاكل. الميكروسفت أبطاء من أيفون ولكنه أسرع من أندرويد بقليل. بعض أنظمة الويدوز سل فون مثل رقم 7 شبه فارغ ولكن تم تحسينه في الثامن وعادتا النسخ العربية يكون فيها مشاكل أكثر من الإنكليزية.

ثامنا: هل تهتم لسعت البطاريّة؟ فانظر الى mAh ومن أي مواد مصنوعة.

تاسعا: الأندرويد متوافق تماما مع غوغل سورتش Google search و YouTube, Gmail, Google Earth, messenger  أو أي خدمة من غوغل. أيفون iPhone متوافق مع حاسوب أبل Apple computers. BlackBerry بلاكبري نظام أيضا يعتمد على تشغيل عدة برامج في نفس الوقت multitasking  مثل الأندرويد. و بلاكبري سريع باستخدام الأنترنت ولكن أسواق برامجه محدودة النطاق. وقد يندمج معه الويندوز.نظام Symbian يستعمل من قِبل Nokia, Samsung, and Sony Ericsson وهو يعتمد multitasking  ولكن عدد برامجه على الأنترنت قليلة. للمزيد  for more.. .

القارئات الإلكتونية e-pads readers :

هي صفيحة تشبه الخليوي ولكنها أكبر وتختلف من نوع للأخر. منها تعرض الصفحات ملونة ومنها بالأبيض والأسود، منها يخرج أصوات ومنها لا، وقد تستعمل قلم خاص ببعضها وتقراء PDF (Acrobat Reader).

أحجامها 7 و 10 إنش عرضي diagonal والبعض يحتوي على 6 و 8 إنشات. أكثرهم شهرة …

iPad (Apple OS), Samsung (Android OS), LG, Kindle, HP, ASUS, Lenovo, Panasonic…some can accept SIM card (to make call) some not. for more…

Car tires

Cars tires

English Arabic

After you read this, you will be able to know about.

  1. Car Tire Description and construction
  2. Tire Code
  3. How to select your tire
  4. Take attention to

Car Tire description and construction

A tire (or tyre) is a ring-shaped covering that fits around a wheel‘s rim to protect it and enable better vehicle performance. Most tires, such as those for automobiles and bicycles, provide traction between the vehicle and the road while providing a flexible cushion that absorbs shock.

The materials of modern pneumatic tires are synthetic rubber, natural rubber, fabric and wire, along with carbon black and other chemical compounds. They consist of a tread and a body. The tread provides traction while the body provides containment for a quantity of compressed air.

Tire Construction

Tire Construction

Tire Construction

Tire Construction


The tread is the part of the tire that comes in contact with the road surface. The portion that is in contact with the road at a given instant in time is the contact patch.

The tread pattern is characterized by the geometrical shape of the grooves, lugs, voids and sipes. Grooves run circumferentially around the tire, and are needed to channel away water. Lugs are that portion of the tread design that contacts the road surface. Voids are spaces between lugs that allow the lugs to flex and evacuate water.

Car Wheel

Tires are mounted onto wheels that most often have integral rims on their outer edges to hold the tire. Automotive wheels are typically made from pressed and welded steel, or a composite of lightweight metal alloys, such as aluminium or magnesium. These alloy wheels may be either cast or forged.

Tread void or grooves

Grooves are the voids between treads, which provide channels for rainwater, mud, and snow to be channelled away from the footprint.


Tread lugs often feature small narrow voids, or sipes (on tire shoulders),  that improve the flexibility of the lug to deform as it traverses the footprint area. This reduces shear stress in the lug and reduces heat build up due to air circulation in its grooves.

Wear bar

Wear bars (or wear indicators) are raised features located at the bottom of the tread grooves that indicate the tire has reached its wear limit and should be replaced.


The bead is that part of the tire that contacts the rim on the wheel. The bead is typically reinforced with steel wire and compounded of high strength, low flexibility rubber. The bead seats tightly against the two rims on the wheel to ensure that a tubeless tire holds air without leakage.

Ply / body plies

Plies are layers of relatively inextensible cords embedded in the rubber to hold its shape by preventing the rubber from stretching in response to the internal pressure. The orientations of the plies play a large role in the performance of the tire and is one of the main ways that tires are categorized. This is important for road holes, to hold on, when the car fall in, without tire explosion. Plies are rated in categories (4,6,8) and can be reinforced to hold over the road holes. Three types of ply are: Diagonal (Bias-Ply) tires, radial tires, and steel belts. For more…


Cushion is a flexible pillow that absorbs shock.

Tire Codes


  • P: Passenger Car
  • LT: Light Truck
  • ST: Special Trailer
  • T: Temporary (spare wheel)
  • R#: Radial rim diameter in inch (multiply by 25.4 to get R in mm)

Load code is the maximum load should be loaded by single wheel. Make attention that the wheels which hold the motor take higher load than the other two. Usually the front wheel (or where the motor) the weight distribution is 56% for front and 44% for the rear wheels. The tire load capacity has its own safety factor. But if you live in a country or area with a big or un-normal road gore or cavity take 50% as additional weight and if no metallic plies in the tire. Usually you have this metallic plies if you have a problem with your road in your country.

Tire diameter calculation as follow: (Rim diameter [inch])* 25.4 [mm] + 2x 9Ratio of height to width) x (nominal width of the tire [mm]) = tire diameter [mm]


for 35 PSI, 35 degree C (95F)Load code 35PSI


Speed rating is represented by an index. The allowable maximum speed is for limited time which is 10 minutes.

Speed ratings make a difference not only in regards to speed, but in regards to ride comfort, wear and cornering ability. Typically, the higher the speed rating, the better the grip and stopping power, but the lower the tread life. You can always increase the speed rating of the tires on your vehicle for improved performance.

The speed rating code mean that the tire can hold up to its rated speed, but the load should not be 100% of the select tire maximum load.

For example: selecting ‘S’ it mean we can load 100% of its rated maximum load 100% until the speed 180km/h. But for higher rated speed such ‘W’ we can reach 100% of the maximum rated load up to 240 km/h, over that we must decrease 5% each additional 10km/h over 240km/h. Meanwhile the pressure increase by 1.5PSI each 10km/h, so for that do not load a heavy load if you want to go near the maximum speed.

Additional marks

There are numerous other markings on a typical tire, these may include:

  • M+S, or M&S: Mud and Snow; A tire that meets the Rubber Manufacturers Association (RMA) and Rubber Association of Canada (RAC) all-season tire definition.[20] These are all-weather tires, with self-cleaning tread and above-average traction in muddy or very light snowy conditions, and for low ambient temperatures. Spike tires have an additional letter, “E” (M+SE).
  • DOT code: All tires for use in the USA have the DOT code, as required by the Department of Transportation (DOT). It specifies the company, factory, mold, batch, and date of production (two digits for week of the year plus two digits for year; or two digits for week of the year plus one digit for year for tires made prior to 2000).
    • TL: Tubeless
    • TT: Tube-type, tire must be used with an inner-tube
    • Made in …: Country of production
    • C: Commercial; tires for light trucks (Example: 185 R14 C
    • SL: Standard Load; tire for normal usage and loads
  • XL: Extra Load; a tire that allows a higher inflation pressure than a Standard Load tire, which increases the tire’s maximum load
  • RF: Reinforced — for Euro-metric tires, the term ‘reinforced’ means the same thing as ‘Extra Load’[20]
  • Arrows: Some tread designs are “directional”, and designed to perform better when driven in a specific direction (clockwise or counter-clockwise). Such tires will have an arrow showing which way the tire should rotate when the vehicle is moving forwards.
Tire rubber characteristic / traction rate

Traction is rated either A, B or C; with A being the best case traction and C being acceptable in traction but inferior to both A and B. Traction test are often very misleading as it is, by actual testing, a measure of the tire’s ability to stop in a ” straight ahead” condition, on a wet surface of concrete or asphalt. It has no testing for cornering or acceleration capabilities. One may infer things about the latter but one may be incorrect in these inferences.

Temperature is the test of the tire’s ability to withstand heat. Like traction, temperature is rated A, B or C; with A being the best case of a tires’ ability to withstand heat and C being acceptable but inferior to A and B. Heat is a killer of tires and the largest offender is either under inflation of overloading of the tire. Another offender is selecting a tire with an insufficient temperature rating for your specific needs. So make sure if you select the appropriate tire temperature rate suitable for your country.

Traction Grades

The tire traction of grade ‘AA’ on Asphalt is 0.54 g-Force, and from the table the grade ‘AA’ is the best and can stop the car faster than the other grades. In bad asphalt quality we prefer to use the grade ‘AA’ or at least ‘A’ to help the car to stop. And from the table below, the asphalt quality is good one. So bad asphalt quality assumed as concrete (no gravels on surface) ‘AA’ gives 0.41 g-force which is not bad, and better than B or C which is 0.26 on bad asphalt.

Traction Rates
Traction Rates

The test should be performed with a special measuring vehicle where the  tire is braked with locked wheels on wet asphalt and wet concrete road  surfaces.

  •     A – indicates the best classification in accordance with certain     requirements;
  •     B – is a slightly lower classification;
  •     C – indicates the worst (or lowest) value.

A tire with value C, therefore, has the poorest wet traction.

Temperature Grades

Temperature Grades
Temperature Grades

The temperature grades represent the tire’s resistance to the  generation of heat when tested under controlled conditions on a  specified indoor laboratory test wheel.

  •     Sustained high temperatures can cause the materials of the tire to     degenerate and thus reduce tire life
  •     Excessive temperature build-up can lead to tire failure
  •     Federal law requires that all tires meet at least the minimal     requirements of Grade C
  •     The temperature grade is established for a tire that is properly     inflated and not overloaded

for more… and more…


How to select your tire

From your car catalogue select the appropriate tire.

For example 255/60 R17 106H All season and (option) 275/55 R17 109H for winter. Your tire diameter is equal to 17″x25.4+2x(255*0.6)=737.8mm.   Car weight 2093kg (empty) so each tire should be rated as load:  Total weight*0.56 /2, the  total weight is 2093 kg plus 80kg per person and for safety fill the trunk with some load (SUV or this example is for 4 wheel drive) 300kg => (2093kg+5person*80kg) *0.56/2= 698. when we load the extra weight on the trunk (300kg) the load will be distributed (fast estimation) by half (front-rear) and the load symbol will calculated as follow: ((2093kg+5person*80kg+300kg) *0.5/2) x safety factor[1.2 for road conditions] = 837 kg. or for 32 PSI your selection is 106 (830 kg). And at 35 PSI the tire rated load is 870 kg.

So when you load your car with some weight, increase the tire pressure and reduce your speed.

If your car maximum speed in speedometer is 240km/h and your country allowable maximum speed is 120km/h (and you will respect the regulation) you can select tire speed rating between 180km/h and 240 km/h(not less due to some safety in case of you emergency car use) so symbols can be from ‘S’ to ‘V’.

You should know if you need ‘all season tire’ or ‘winter tire’. If you are in a region such mountain we prefer to buy winter tire for winter season, this is best for slopped or skidding roads, bad asphalt (Traction class AA or A). also make sure you have M+S symbol (Mud and Snow).

winter Mud and snow

Winter Mud and Snow

Before selecting your tire, read the specification and manufacture data. you should to know (as we will describe the most of them) what you want to care about:

Dry braking, Wet braking, Handling, Hydroplaning, Snow traction, Ice braking, Ride comfort, Noise, Rolling resistance. Usually you will find a rate for each option or characteristic in the manufacture website. If you are leaving in a hot country, select temperature rate A and if your road way is very slopped (up or down, traction or breaking) you should select traction rate ‘AA’ or ‘A’ in case of wetted or bad asphalt quality.

Make attention

Passenger car Tire inflation

Every vehicle should have a manufacturer recommended tire inflation  value, usually on a sticker on the driver’s side door jamb.

Small car tire pressure at front 30 to 28 PSI and rear 28 PSI

Medium car size, front (motor) 32 to 30 PSI and for rear 30  to 28 PSI

SUV / 4×4 truck need 35 to 32PSI for front and 32 to 30 PSI for rear, in case of heavy load, use for rear 35 PSI.

Those as fast pressure selection, and below there are a scientific decision.

If you want to load some weight on the trunk you should modulate the rear tire pressure.

Reduce top speed

The faster a tire goes, the more heat it retains and the faster it wears.  A 20-mph increase in average speed, from 55 mph to 75 mph, can decrease tread life by up to 30%.  This change in speed will require a 60,000-mile tire to be replaced after only 42,000 miles.

Rotate your tires regularly:

Tires wear differently depending on their position on the vehicle.  To keep all tires wearing evenly and to maximize tread life, they must be rotated at regular intervals.  Industry recommendation is to rotate your tires every 2nd oil change (about 6,000 miles). You should refer to your owner’s manual for manufacturer recommendations specific to your vehicle.

Maintain proper tire inflation pressure: Tires that are underinflated by 20% will reduce tire life by as much as 16%.  Using real numbers, a car’s tires that are underinflated by 6 psi will cause a 60,000-mile tire to last only 50,000 miles.  Temperature changes also have an effect;  a 10-degree Fahrenheit change in temperature will result in a 2-psi difference in tire pressure. (1 mile = 1.61 km)

Speed and load

If you’re going very slowly, you may be able to carry heavier loads than at “normal” speeds.  With a tire like an 11R22.5, load capacity can increase 185 percent when the vehicle is stationary if you boost inflation by 40 psi. Also increasing the speed will increase the road friction with the tire, and this yield to decrease the tread life or increase the wear. Speed increase the pressure and tire-air temperature. If we take tire speed rated for example ‘W’ as reference of car speed 190km/h with 35 PSI, the pressure will increase 1.5 PSI each additional 10 km/h until a certain limit where this become stable at 240km/h at 7.5 PSI as additional pressure. For ‘V’ rating the pressure start increase from 160 km/h up to 210 km/h 1 PSI each additional 10km/h. Speed rating ‘S’ start from 160km/h up to 180km/h increasing by 1PSI each 10km/h. When the pressure For more info and other rating speed…

Load and tire pressure

The rated load as from the table above is rated at 35 PSI (1 PSI = 6.893 KPa). To calculate the maximum permitted load at a specific pressure, use the following approximated formula: Load = (rated load) x SQRT(PSI / 35) within 1% error if your selected table is from below tables at 35 PSI or if the selected table is from above at 42 PSI the formula will be Load = (rated load) x SQRT(PSI / 42). For best estimation refer to the table below

TireLoadLimitsAtVarious PSITireLoadLimitsAtVariousPSI -2(Click to enlarge)

Relation of speed and Pressure to load.

Relation between speed and pressure or speed and load are estimated as the following formulas :

Speed-Pressure (Km/h – PSI) , Rational Model

Logestic SpeedPSI

Speed-Load (Km/h – weight % change), Hyperbolic Decline


Speed - Load - Pressure

Speed – Load – Pressure

Increasing the load on tire, yield to increase air-tire temperature and friction, this increase the wear of the tire. So when driving, the tire pressure may increase by 5 to 7 PSI due to the speed and temperature. (Note that in summer the asphalt temperature may exceed ambient air temperature by 15 degree Celsius).

For further reading about Speed – Pressure

Decreasing the car speed, allow you to increase tire pressure or put more load instead.

(Note: the relation between % load and extra PSI is not linear)

Manufacture Tire tests

There are many tests should be applied to new tire model. Federal has one of these methods and another standard has something similar.

In a rotating test machine, and in each step, the velocity start from lower speed up to the maximum rated speed (for this model), and 10km/h each 10minutes the speed will increase. Then a series of test that combines the speed changes and load changes. The load start from 75% of the rated load then increase by 5% each step plus the modification of the speed. Overall phases are around 24, but some tests will applied to 48 hours at 110% of the rated load at speed 80 km/h and at higher rated speed (100 km/h) apply 90% of the rated load. The tires rated for high speed (‘S’ rated and up) will subjected to higher speed test such 160km/h for one hour.                                                   This is a brief description and for more refer to…

 Tire pressure at ‘rated speed’ temperature relation

When checking the pressure of your tires, it is best to develop a routine. That is, try to check them in a shaded area at the same time be it morning of evening and make sure that your check the pressure when the tires are ‘cold’. We try to check our tire pressure at least once a month and always before a highway trip or performance driving.

 As approximate estimation of pressure T1 / T2 = P1 / P2   , Where T is the temperature in Kelvin and P is the pressure in any unit (PSI or Pa). For example if you regulate the tire pressure at 20 degree Celsius to 32 PSI, it will be 33.75 PSI (Slightly less) at 36 deg. C. or 9 deg. C add around 1 PSI of pressure.

Changing tire size -> Bigger Tire Size

What happen if I select a bigger tire size for my car?

BiggerTireThe car motor apply a momentum and torque at the centre of the wheel, the wheel rotate in the ‘+’ sign direction and this to be happen without skidding, the road should make a reaction force ‘F’ in the opposite direction of car movement. When we increase the tire size ‘R’ the torque created at the centre (opposite to motor torque) increase with ‘R’ and the car acceleration will be less than a smaller tire size, but once the speed is constant (no acceleration) the car speed it is increase as ‘R’ increased but the kilometre or millage in front of you in speedometer or millage-meter still unchanged, but the car run slightly faster by ‘R’ / ‘r’, where ‘r’ is the initial car tire. Also you should note that the brake should be stronger than ‘r’ case to let the car to stop at the same distance, unless the stop distance will be also increased. So do not increase your vehicle tire size if you not need to use it for off-road driving.

Tires type

1)  Mud and Snow (M+S) Rating

All-season tires are branded with the M+S symbol, meaning they have met the Rubber Manufacturers Association’s (RMA) requirements for an all-season tire. These tires are designed to provide year-round traction on wet and dry roads (including light snow).  If you’re looking for all-season traction, make sure your tires have the M+S symbol on the sidewall.

Mud and Snow

Mud and Snow

2)  Severe Snow Use Rating

A step up from the M+S rating, these tires have met the RMA’s requirements for use in severe snow conditions.  Tires rated for severe   snow use will have a ‘mountain and snowflake’ image imprinted on the sidewall.

Sever Snow

Sever Snow

3) Winter rating

As the temperature drops below 40-degrees Fahrenheit, tire rubber hardens, significantly reducing grip with the road.  The good news is that winter tire technology has come a long way in recent years to provide excellent winter traction, ice grip, and ride comfort. Rubber compounds in winter tires are designed to stay softer at cold temperatures.  This gives the tire much needed flexibility to ‘grab’ the road with the thousands of ‘biting edges’ provided by the sipes or cuts in the tread.  Winter tires can be categorized in three groups:

  • Studdable Winter Tires:

    Studded tire

    Studded tire

  • Studless Winter Tires:
  • Studless winter tire

    Studless winter tire

    These tires are designed to provide the best balance of winter traction with ride comfort.  These tires rely on the cuts, or sipes, in the tread to provide thousands of ‘biting edges’ when the tire comes in contact with the road.

  • Performance Winter Tires:
  • performance winter tire

    performance winter tire

    Designed for maximum winter traction while maintaining high-speed performance characteristics.  These tires provide superb steering response, ride comfort, and grip in all types of winter conditions.

To help water evacuation, you should be aware of tire pressure, a good pressure help water to disperse. Under-pressure let tire tread to become obstacle for water evacuation and over pressure reduce stability of the vehicle.

Tire water evacuation

Tire water evacuation

Water evacuation

Tire Water evacuation

Summer Tires:

Maximum traction on wet and/or dry roads is what summer tires are designed for.  These tires may be used in the spring, summer, and fall, but are not intended for use in cold weather (including snow and icy conditions).  Summer tire looks smooth compared to a winter or all-season tire.  This enables the tire to grip more of the road surface, but hinders it from gripping well on snowy or icy surfaces.  If you drive your vehicle in winter conditions, you should have a set of winter or all-season tires to compliment your summer tires.      

Summer TireSummer Tire

Reference: season

Symmetrical and asymmetrical tires

Thread Types

Thread Types

Symmetrical (tread)  tires are typically quiet, and it is better in hydroplaning, where the water evacuation will be symmetrical and less annoying to other cars, and each tire is subjected to the same force from water. The images above are symmetrical type.

Asymmetrical tireAsymmetrical tread tires are used for sport cars. Asymmetrical tires have large blocks of tread on the outside to increase  cornering stability and narrower blocks of tread along the inside of the tire to  aid winter or wet weather driving. But the asymmetric lead to non uniform force distribution in hydroplaning (aquaplaning)  (driving in watered road or heavy rain) for each tire, but it will be balanced by the 4 tires. So never mix symmetrical with asymmetrical tires.

Asymmetrical tire

 Directional tread usually takes the form of v-shaped grooves that help to disperse water from the centre to the edge of the tread. And the rib sometimes can be like a teeth to increase traction or breaking with ice. And in another case it is used to increase tire stiffness or rigidity

Ice tread

Ice tread

Tread type

Treads shape are important for traction, braking, cornering, hydroplaning.

  • -The fine lines (or zigzag) are made to reduce noise of tire on road.
  • – The big channels are for water evacuation to reduce the hydroplaning on road.
  • -Increasing number of tread, increasing the road adherence in snow or wet road


Low noisy tread
Low noisy tread

For more about tread shapes…

Aquaplaning or hydroplaning by the tires of a road vehicle, aircraft or roller coaster occurs when a layer of water builds between the wheels of the vehicle and the road surface, leading to a loss of traction that prevents the vehicle from responding to control inputs. (

Aquaplaning Hydroplaning

Aquaplaning Hydroplaning

To reduce aquaplaning effect, and reserve car stability, make sure you appropriate inflate your tire, and tread should be new. As velocity increased over water the aquaplaning increased, and the adherence between tire and the road decreased, once this occur it is difficult to re-maintain car stability.

Refer to and check the water layer below tires at different tread and different tread thickness.

For an idea how water evacuate from wheel, refer to

Aquaplaning Hydroplaning

Aquaplaning Hydroplaning

 Check on youtube aquaplaning effect when the car loss adherence (contacts) with the road.
For water evacuation efficiency with pressure, check
underinflated tire

underinflated tire

Good inflated tire

Good inflated tire

How to select the right thread type?

For passenger cars it is good to select the low noisy treads, in another hand the sport car doesn’t need that due to exhaust system sound is higher.  Select tread types by knowing the asphalt quality, low quality need more number of thread and avoid smooth treads. Road shape, if a pool may form in your road, you should select the big channels to help evacuating water. For off-road drive you need a thick treads and coarse one to help drive on gravels or rock.

Increasing channels (fine or thick) help to dissipate heat from tires. To let the tread work its job, you should inflate tire with the appropriate pressure. The tread on the tire edge are important for off-road or parking near (or contacting) the edge of pedestrian sidewalk.

Illustrations and explanation for tire wear

Under Inflation

Under Inflation

Under-inflation has caused this tyre to wear on the outer edges of the tread, leaving the central tread area far less worn. The tyre inner-liner can also degrade.

Over Inflation

Over Inflation

Over-inflation has resulted in the central tread area being forced into contact with the road causing rapid or crown wear.



A typical example of the wear pattern caused by front wheel misalignment, (Toe-in or toe-out). The edge of the tread is “feathered” and worn progressively from one side.

Camber Wear

Camber Wear

Excessive wheel camber has caused sloping wear on the outer edge of the tread on one shoulder of this tyre.

Illegal Wear

Illegal Wear

This tyre has been used well after reaching the legal minimum pattern depth of 1.6mm across the central ¾ of the tread, going around the complete circumference of the tyre.

End of Life

End Of Life

This tyre has reached the legal minimum pattern depth of 1.6mm.

Emergency Braking

Emergency Braking

An emergency braking manoeuvre with this tyre has caused the tyre to rapidly wear through the complete casing causing the tyre to deflate.



Sharp objects can cause considerable damage rendering a tyre unserviceable.

Studded tireImpact Damage

Impact Damage

This is damage caused by an impact to the sidewall. The bulge or “egg” indicates localised casing damage.

tire underinflated / overloaded

tire underinflated / overloaded


Wheel bolts fixing order / wheel installation

Start fix wheel bolts diagonally not in order.


General references:

Smartphone and e-pads

Arabic    English

Post Goals

  1. What is a Smartphone
  2. Main parts of smartphone
  3. Cell phone Operating system
  4. How to select your smartphone
  5. What is e-pads reader
Understanding smart cell-phone function

A smartphone is a mobile phone built on a mobile operating system. This type of phones called by smart because it contain between 10 and 15 sensors plus can an open source of applications. Sensors may detect a lot of information which may help the user to know his location (3D), speed, detect light luminous, noise dB, find the magnetic Earth North, detect metal,  atmospheric pressure, temperature (usually of the battery)…, take photos, open internet, running a wide range of tools (It is similar to a computer but with limited capacity and speed). So the smartphone is one device can replace a lot of another devices such: Old mobile phone, a lot of devices which may have sensors, dictionaries, notebook, mp3 or mp4 pod and recorder, radio, (also it may replace small TV and remote control for compatible modern TV), some of them it may have a pen, camera (still photos and videos, but limited power for camera [lens focal range] but a good number of pixels [resolution]) , calculators (normal, graphics, programmable…), diary pad, a large capacity of people contact information, torch and flashlight,  electronic games devices, can be used as flash memory storage ,and for software we have… chatting, Engineering software (AutoCAD, Gas calculation, pipes size,…) Excel, word, pdf reader, stocks processing, buying software or product (e-commercial) and any software made for computer it may make for smartphone), A wide range of photography (panorama, editing photos…), show a precast of weather using the internet or any service you may have on computer you will have on this phone type using (3G, 4G… and Wi-Fi) and so on.

Main parts of smartphone

  1. LCD or LED and touchable screen with different size. which display the interface with the user.
  2. Mobile phone antenna radiation  between 1850 and 1900 MHz or Ultra High Frequency (UHF)  waves at power between 1.2 to 1.8 watt. This frequency hold the communication of the call, message, or internet through mobile co. or provider.
  3. Wi-Fi antenna to connect to a modem (modulator-demodulator), router for internet use (usually at 2.4 GHz)
  4. Bluetooth to connect one cellular to another without wire, and use to transfer data such text, images, videos, files…for more…
  5. CPU core (central processor unit) and memory. The base memory divided into two parts one for OS (operating system) use and one for data storage and can be used as flash memory (Known as USB) and other memory is named SD card (Secure Digital memory card) this can be added later when user needs for it. CPU speed affected by CPU bus data transfer in bits (now we have 32bits), CPU frequency or fictive operation frequency  (any real operation need many frequency from the CPU to be done). Since we have a high CPU frequency (modern cell phones) they (phones) can operate in multi-tasking (many application can be run in the same time). Also RAM has an internal frequency to transfer data from it to the CPU or other parts. for more…more…, and more…
  6. Battery, is made from lithium-ions (Li-ions) cathode and anode are made from Li as base material and other material. Capacity measured by mAh (milli-Amper x hour) for more…  and more…
  7. SIM card (Subscriber Identity Module or Subscriber Identification Module), is the card to connect through to your cellular provider. for more…
  8. Charger, there are 110 / 220 V socket charger, USB charger cable which we can connect it with a computer, TV, receiver or any device has USB connection and car adapter charger.
  9. Finally the sensors and devices: (Not all mobiles have these sensors)
    •      Accelerometer: Measure the acceleration in all directions (the change of phone speed) m/s2
    •      Gravity sensor: Measure the Earth gravity on the phone.
    •       Gyroscope sensor: Measure the angle speed or cell phone speed of rotation (radian or degree… per second)
    •       Light sensor: Measure the light intensity in lux(normal office lighting is 250 lux, human can start to see at 0 – 1 lux, Sun effect more than 1000 lux ).  this help to create the following options: turn back the cellular the sound  goes off, or if it is in a dark place the phone increase the ringing volume and so on.
    •       Linear acceleration sensor: Measure the linear acceleration (is the same as acceleration above but it remove the Earth gravity effect, to become linear as in depart or stop in motion)
    •       Magnetic field sensor: Measure the magnetic field in μT (Micro Tesla) in all directions, this can help to find the Earth magnetic North direction or any desired magnetic direction, also help to find where we have a magnetic field around the phone and how its value, this help to detect electrical field and metal. So sometimes called metal detector. The magnetic field change in amplitude and direction when enter some metal, so this help to find those metal when the field changed dramatically. this also help in some precision to find metallic pipes under tiles / floor and embedded in wall, also can help to find steel rod in concrete columns (superficial rods) and so one (Cannot detect Gold 😦   )
    •       Microphone: This a normal microphone to get the sound to the device but also get its amplitude, so we can know the noise level in decibel (dB). For an idea a studio human starting to hear from 0-1 dBb, recorder studio should be not more than 20dB, normal conversation 40 to 60dB, where 60dB is noisy ambient, airplane 80-90dB and rocket at 120dB (logarithmic scale, in logarithm scale mean that a noise of an additional 1dB mean it is greater 10 times in power, human can notice easily 3dB in change). for more…, more…,more… and more.
    •       speaker: Speaker is where the sound exist the device, and this may has 70dB.
    •       Orientation sensor: This base on Earth magnetic field and the smartphone direction.
    •       Pressure sensor: Measure the atmospheric pressure sensor in mPa (milli-Pascal). The 1Atmospheric is 1bar pressure = 101325Pa in normal condition. When the pressure goes above 100000Pa the weather turn warmer or hot, and below 96000Pa is colder.
    •       Proximity sensor: This determine if an object pass in front of the phone, this help to create the following options: turn back the cellular the sound  goes off, take the phone near the ear and the phone call someone, or detect a motion, or stealth.
    •       Ambient temperature sensor: Detect the ambient temperature (sensor putted in the opposite side of the battery) and this may affect by battery and screen temperature if it is on for a long time.
    •       Relative humidity sensor: Measure the relative humidity of the ambient air, below 40% is dry and above 70 is humid. The humidity indicate the amount of water vapour in the air.
Cell phone Operating system (OS)

Each cell phone may has its own operating system, and this OS created by mobile manufacture. The latest smartphone has his own operating system as Nokia, Motorola, Sony-Ericson, Sony, LG, iPhone, Samsung, blackberry, HTC, Microsoft… (latest number is 83 cell phone manufacture)for more….

After the launch of Android OS all the story changed, and now they are combined in categories as follow: iPhone has still his own OS from Apple, Samsung, Motorola, HTC… have Android OS, also HTC, and others have windows phone OS. the OS are: Android, Apple iOS, Symbian, Blackberry OS, BlackBerry playbook OS , WebOS, Bada OS, Windows Mobile, Windows Phone OS, and MeeGo OS. for more details…

How to select your smartphone

You should take attention to some features you may interest.

first, Do you interested on speed? So you have to look to CPU core model, CPU frequency (GHz), Ram capacity and the operating system. And the OS is the most important. In the market today we have Android OS which is slow comparing to Apple iOS (iPhone) and other OS. As you add application to your phone the Android OS will slow down due to fragment memory, in the market we have defragmenter software and this can enhance 30% of fragment memory but Android still slower more than 50% or 100% (It take twice the time when using base application (built-in).

Second, are you interested to memory capacity for data storage? You should ask if you can add memory to your phone. Android allow you to add; and its hardware is has this capability but iPhone cannot. But also Android need more memory to run its multi-tasking application where Apple iOS need less memory because he run one application at a time.

Third, In Apple iOS you cannot use your phone as USB flash memory and you should have iTunes to transfer data, but Android allow you to manage your data in and out as you use a simple USB memory.

Fourth, ask if you want high video quality and sound, usually iPhone has slightly better, but others use Android system have good quality (Samsung, HTC, Motorola, Sony, LG…)

Fifth, what types of sensors you want, which sensors are important for you and which you don’t mind.

sixth, screen size, are you prefer for big size for more clarity or some of such device allow to see graphs and engineering drawing better, but is it practical to take with you such size of phone where you go?

seventh, do you mind about paid application or you prefer most of them to be free. Android market is an open source and flexible and has higher number of application are free. Android has higher number of unstable application compared to iPhone this due to open source and some developers still have bugs in their software. Microsoft mobile is slower that iPhone but slightly better than Android and has the disadvantage of the iPhone. Some windows phone OS ( version 7) is almost empty, does not has any advantage. (version 8) is better but still has bugs as Android especially Arabic versions.

Eighth, are you worry about battery storage? take a look to mAh of the battery and from which material is made.

Ninth, Android is fully compatible with Google as search, YouTube, Gmail, Google Earth, messenger… and any service from Google. iPhone fully compatible with Apple computers and software. BlackBerry is an operating system whose main characteristic is multitasking as Android and now they planning to install windows phone OS but the BlackBerry OS itself is limited to some feature like internet and messaging are very fast but its application in the market is limited. Symbian is used by Nokia, Samsung, and Sony Ericsson and also it is fast but limited in the application in the market but it is multitasking. for more… there are 10th of site describe the advantage and disadvantage, but some of them are not objective.

e-pads reader

Is electronica pad reader, there are many types. Some of them can read news and PDF (Acrobat Reader) or books format, only for reading and making some notes and highlighting.

Some of them are similar to smartphone with bigger screen 7″, 10″ diagonal screen and some have intermediate size. The most famous are iPad (Apple OS), Samsung (Android OS), LG, Kindle, HP, ASUS, Lenovo, Panasonic…some can accept SIM card (to make call) some not. for more…