Software refers to the non physical parts of a computing system.  Examples are the programs which contain the instructions.  The software is written in the programming language such as VB, Java and C

Firmware is the program written on an embedded device such as a microprocessor or a microcontroller.  It controls the functioning of the microprocessor IC

It is written in the assembly level language. It is called firmware as it interfaces between the software and the hardware.

Hardware refers to the physical components of a computing system such as the processor, memory and the peripherals.

The key difference is that in a microcontroller, the memory (ROM and RAM) and the peripherals are fabricated on a single IC. A microprocessor, on the other hand, does not contain the memory and the peripherals in itself.  They are separately mounted and connected.

Microcontrollers are used for specific operations, such as to control and operate a washing machine or a traffic signal.  A microprocessor can be installed for a specific function in a larger system.  It is not designed for a single operation.

The speed of a microprocessor is above 1 GHz while the speed of the microcontroller is around 50 MHz.

Microprocessors can handle greater complexity as compared to microcontrollers.   They also use more power than microcontrollers.

Embedded Electronics, as the name suggests, refers to electronic hardware and software that is embedded or attached to the equipment being controlled.  

The component may be a robotic arm in an assembly line or a life support device in an ICU.  Today, Embedded Electronics can be found in all areas of life.  The washing machine and the refrigerator at home are also controlled by embedded electronics.

The advantages of embedded systems are their small size, low cost and power consumption and their rugged construction.  The program and the logic of machine operation can be easily modified.  The cost of embedded systems are lower as they are mass produced which reduces cost.  

Embedded systems can be built using both microprocessors and micro controllers.  Embedded systems can be used as standalone units or as part of a larger network controlling a bigger system.  

Programming Embedded Systems

Embedded systems can be programming using assembly level languages.  The assembly level languages are compiled into machine level using compilers.  The program is stored in the nonvolatile memory of the system.  Microprocessors and microcomputers will have their own programming languages specified by the manufacturers.  A good understanding of the C programming language will be useful in programming embedded systems.

Piston valves function by a piston which moves in a cylinder.  The movement of the piston serves to open or close the valve.  The Piston has a hole through it.  As the hole moves up and down, the valve is opened and shut.  Piston valves can be used in media such a steam, water, compressed air, etc.

The valve can be mounted in the vertical or horizontal direction.  The valve has a handle which is to be rotated.  The rotation causes the piston to move in a linear direction.

Piston valves are also to be seen in musical instruments.

Methane Fermentation is a process of eliminating organic matter in the sludge.  In the process, methane is generated along with carbondioxide.  Methane can be used as a fuel.

Methane Fermentation involves digestion of organic matter using bacteria.  The bacteria are called methanogens.  

The digestion happens in the absence of oxygen (anaerobic digestion).  Anaerobic digestion will reduce the organic matter by about 50 percent.  It is posible to extract about 1000 litres of gas from one kg of organic matter.

The residual matter can be used as fertilizer.

Sludge Conditioners are chemicals which are added to sludges before they undergo the de-watering process in water treatment plants.  The dewatering process removes the water and the solid particles.

A sludge is a colloidal solution with solid particles suspended in water.  For dewatering to be effective, the smaller sludge particles should join together and form larger particles.

This is done by adding sludge conditioners.  Sludge conditioners work by altering the pH value of the sludge.  This results in coagulation.  The water and the particulate matter separate.  Different sludges have different pH value for coagulation.

Once the sludge has coagulated, it can be easily dewatered using centrifuges or vacuum filters.

Adiabatic Flame Temperature is the temperature which will be achieved if a combustion process is complete.  It assumes that there is no change in work, no heat transfer and no change in kinetic and potential energy.

The hypothetical temperature will be achieved in the event of a stoichiometric combusion ( a combustion without any residues)

The actual temperature which will be obtained is usually lower than the adiabatic flame temperature. This is due to factors such as heat transfer, incomplete combustion, etc.

Every fuel will have an adiabatic flame temperature.  It is the theoretical maximum temperature which can be achieved using the fuel

Conductivity is an important parameter of industrial liquids.  Conductivity is measured for liquids almost all liquids.  The conductivity of the liquid gives an idea of the ions in the liquid.

The conductivity of a liquid is measured using special conductivity sensors.  The unit of conductivity is siemen/cm.  A siemen is 1/ohm.  The unit of conductance is sometimes referred to mho (ohm written in reverse).

The conductance is usually a very low value for conducting liquids such as water.  It will be of the order of a millionth of a siemen, in microsiemens.  Highly pure water, for instance, will have a conductivity of 1microsiemen/cm.

Measurement of conductivity
Conductivity is measured by measuring the conductivity of a liquid between two electrodes whose area and distance between each other is fixed.  This is known as a cell constant.

A cell constant of 1 implies that the electrodes will have a surface area of 1 cm2 and will be spaced 1 cm apart.

Magnetic flow meters are used to measure flow of liquids that are conductive.  Magnetic flow meters do not have to physically be in contact with the medium.

Magnetic Flow meters, or Magmeters as they are otherwise called work on the basis of Faraday's law which states that the voltage produced by a moving conductor in a magnetic field is proportional to the velocity of the conductor.

In a Magnetic flowmeter, the conductive liquid such as water is passed through a constant magnetic field.

As the conductive liquid flows between a magnetic field, a voltage is induced in direction perpendicular to the magnetic field.  This voltage is measured by a pair of probes.

The flowrate can be calculated from the voltage induced in these probes.

The magnetic field is produced by a pair of electromagnets whose polarity is constantly reversed. The reversal of polarity is essential to prevent interference due to electrochemical potentials induced where the probes come in contact with the liquid.

The voltage is proportional to the velocity of the liquid, the width of the pipe (diameter), and the magnetic field strength.