Mechanical Engineering -- The Yantra Sastra

Thursday, 21 May 2015

Ethiopia's leap toward solar energy by Eric Mutei ERIC MUTEI in ENERGY

Source : Ethiopias-leap-toward-solar-energy

Small steps can be much larger than they seem, some steps forward become great leaps. Ethiopia, a vibrantly growing economy attracting many investors, will need alternative sources of energy to sustain production and economic growth. It is out of these challenges the country is looking for more clean and renewable energy alternatives.
The country has embraced partnerships with different players in the field of solar energy. The most recent investment topped more than 600 million US dollars in solar power generation. The Ethiopian government, through Ethiopian Electric Power, signed a memorandum of understanding with a US basedGreen Technology Africa (GTA) to develop solar energy plants in the country. The deal will help Ethiopian Electric Power develop a 300 MW new solar project in Ethiopia - with the aim of helping the country hit its goal of expanding electricity capacity from the current 55% coverage to 75% by the end of 2015. These projects will be active in the Ethiopian cities of Dire Dawa, Kombolcha and Desse in the next six months.

A project by the Green Technology Africa

Green Technology Africa has lauded Ethiopia for its efforts to find solutions for a greener country. This praise includes the support for organizations launched internationally by Ethiopians in the Diaspora who have acquired years of training and professional expertise and then choose to return back home to give back to their society.

Why Not Do it Ourselves?

Solar panels capable of producing 236Kw of energy put on display by the Ethiopian Power Engineering Industries (EPEI) at the Addis Ababa Exhibition Centre. Courtesy: Addis Fortune.

As a landlocked country, Ethiopia faces a number of challenges getting imports into the country easily and effectively. With these challenges, the country has sourced alternative solutions in achieving cleaner energy sources. Why not do it ourselves?

The Metals and Engineering Corporation started an initiative of assembling Photovoltaic (PV) solar panels for the first time in Ethiopia. Solar panel production is under construction at Sendafa area in Oromia regional state, 40 km away from Addis Ababa with the aim of increasing solar panels and silicon element production. This plant is an expansion of the solar panel production factory in Tatek area, which is manufacturing more than 20MW panels per year. Upon completion the factory is expected to increase this capacity to 270MW panels. This will facilitate the nation’s initiative to provide electricity to rural areas. This access, remote from the grid system using renewable energy, is a strong direction for the green development strategies.

The nation continues to promote the use solar energy to replace fuel-based lighting among rural households and off-grid electrical needs. The solar energy project underway by the government is aimed to provide electricity to 25000 houses. A total of 150,000 people are expected to gain access to electricity through this project alone, with a capacity of generating 982 MW of power by the end of 2015. The Solar Panel Production Factory was established under the Ethiopian Power Engineering Industry in the Metals Engineering Corporation two years ago with the objective of producing solar panels and substitute the imports. One more project of many the country has in place to electrify the rural areas using renewable energy sources and minimize the use of fuel in order to obtain a green economy.

Ethiopia charting path to a low carbon future with light rail

Source : Ethiopia charting path to a low carbon future with light rail

At the end of a long day at work, the only thing you want to do is get home quickly. You’re exhausted from dealing with your boss, terrible colleagues or crazy clients. But traveling home is just another drawn out nightmare to endure, thanks to the woes of the transport sector. The only reliable and affordable means of transportation for a common city dweller in Addis Ababa is the state operated city buses. Apart from the long stretchy queues, these buses are overcrowded and groaning heavily under the weight of the city residents. Not to mention the endless traffic jams. This is the daily transit scenario in the streets of Addis Ababa.

Long queues for city buses are a fact of life in Addis Ababa, Ethiopia

The scene above was the common case of daily transit until the Addis Ababa Light Rail Transit (LRT) project launched in December 2011. The rail is a first in clean initiative in the horn of Africa to enhance public mobility. The light railway of Ethiopia is the first urban metro light rail scheme to be built in a sub-Saharan country outside of South Africa.

The Ethiopian Railways Corp. (ERC) began construction of the double track electrified light rail transit project in 2012. It stretches 23 kilometers covering the better part of the city, and is a welcome relief for the city residents. The light railway consists of two lines running for a total distance of 32km with underground and over ground sections, 39 stations, and two operators that are the Ethiopian Railways Corporation and Shenzhen Metro. The 41 three-section 70% low-floor light rail vehicles are designed to run in pairs at up to 70 km/h. All have tinted windows and rubber components specified to resist premature aging from the effects of strong sunlight at altitudes of 2400 m.

Rugged interiors are built to last in Ethiopia's strong sunlight and high elevaton

ERC intends to register the Addis Ababa Light Rail Transit project as a Clean Development Mechanism project. The rail project is one of the pillars of a green growth strategy in the transport chapter of Ethiopia’s Climate Resilient Green Economy (CRGE), to consolidate greenhouse gas emissions of the country at 2010 levels. The vision of this rail project was to see a modern railway infrastructure and service by an efficient railway company that supports Ethiopia’s endeavor in building a globally competitive economy that uses electricity and connects the country’s development centers and links with ports of neighboring countries.

The Climate-Resilient Green Economy (CRGE) strategy (PDF) lays down a plan for Ethiopia to develop a carbon neutral, green economy by 2025. According to the CRGE strategy report, under the BAU scenario, emissions from the transport sector will increase from 5 Mt CO2e in 2010 to 41 Mt CO2e in 2030. The development and implementation of a National Railway Network and the Light Rail Transit and supported projects (Transit Oriented Development) will result in significant GHG emission reductions of 9 Mt CO2e/year by 2030.

Two tracks run a total of 32 KM in the city

Building electrified railways lays the base for low carbon transport in Ethiopia and will assure clean transport tomorrow. Railroads can contribute towards severing Ethiopia’s economic growth from diesel fuelled trucks. Availability of reliable and clean transport is a precondition for Ethiopia’s development. Trains can make use of a domestic energy source, hydropower, and help fuel the economy in a green way. The clean character of the fuel without emission of greenhouse gasses and the durable economic structure without dependency on imported fuels is sustainable.

Years ago the air was cleaner, but with the drastic growth in population, more than 4 million, the number of 20 year or older vehicles and developmental projects, the air is polluted above the traffic gridlock. The light rail train as cleaner public transist gives a reprieve to the public, combined with the hope for more electric cars, it is expected to reduce the annual greenhouse gas emissions from the transport sector to less than 9 tonnes by 2030. It is an environmentally friendly venture aimed at combating the ever growing pollution in the city. It is not only convenient, providing transport for over 15,000 people per one direction and 60,000 in all four directions, but affordable for the residents. It is a milestone in helping Ethiopia sustain its growing economy, as Ethiopia is one of the fastest growing economies in the world.

The Light Rail Train has brought glimmers of hope to the common man. At the very least, one can get home easily at the end of the day without the crazy hassle of looking for and struggling in transit. The commuting city residents can breathe easier using clean transit as they take part in building their nation.

Wednesday, 9 April 2014

Driverless cars inch their way closer to reality | GulfNews.com

Accessed on 9th April, 2014 (4:18pm)

Image Credit: Dana A. Shams/Gulf News

Cars that drive themselves? A few years ago, this would have been science fiction. Not so far-fetched now.

Aircrafts have had a autopilot for a long time now. In fact, a lot of
the technology such as cameras, sensors, radars and imaging systems
required to build truly autonomous vehicles are already available.

Multiple experimental vehicles are being tested for varying levels of
operational autonomy. Google’s technology has driven a Toyota Prius over
300,000 kilometres around the US without a single technology caused
accident. General Motors, Toyota, Mercedes-Benz, Audi, BMW and Volvo are
all testing their own full or partial autonomous systems.

Volvo has launched the ‘autonomous valet parking cars’ in Europe.
Nissan recently committed to launch an ‘Autonomous Drive’ system by
2020. The transition is inevitable. We do expect it to happen in a
building block form like advanced driver assistance systems, park assist
systems, or integrated vehicle health monitoring and autonomous systems

Moving from Point A to Point B involves planning and decision-making
about mode of transport, routes, times, safety, comfort, weather, luxury
and convenience. However, it is a fact that a significant percentage of
road accidents stem from human errors. Making vehicles autonomous
globally could be around $300-400 billion of economic impact if you take
into account loss of human life, their economic impact to the society
and the allied claims.

There is a lot to be gained by removing humans from driving. There is
no reason that technology cannot make roads driver-free as seen in cases
of trains/locomotives and aircrafts in autopilot mode.

The question is can we make it affordable, safer and easy to use and
bound by regulations which itself is evolving? Nevertheless, the sheer
number of people around the globe who will be affected by autonomous
vehicles is staggering.

Apart from the primary technology required to actually build a
road-safe autonomous vehicle, we can safely foresee huge regulatory and
infrastructure challenges. Autonomous vehicles make more sense only if
the infrastructure also enables it. Just like electric vehicles required
an ecosystem of charging points that could quickly charge a vehicle
without bringing down the grid, new infrastructure requirements such as
intelligent traffic lights, smart lanes with sensors and automated
parking infrastructure will accelerate the adoption of autonomous
vehicles.

Countries conform to their own traffic rules and implement their own
safety regulation. Any autonomous vehicle system must be ready to be
tested and certified on any safety regulation around the globe. This is a
massive challenge. Companies must be ready to programme and tailor
their intelligent drive systems for different geographies which suit
different cultures.

Also, such vehicles bring in a certain amount of threat to personal
privacy. Autonomous vehicles are built with advanced sensing and
tracking capabilities and are constantly monitored. While this feature
is intended to complement vehicle performance, we cannot overlook the
fact that this may create new security concerns and lend itself to
commercial misuse.

Finally, there is the challenge of customer adoption. Will consumers
adopt something that will change a fundamental way of life? Can someone
give up driving as a passion? This final hurdle could well be the
biggest one, but at the same time, everyone can enjoy the pleasure of
being seated in the driver’s seat calmly without getting ruffled by the
chaos of traffic.

Fuel efficiency has always been a USP for the automotive industry.
Autonomous vehicles can provide better fuel efficiency because they are
equipped with intelligent technologies that enable this.

Safety is one segment where autonomous vehicle can make their biggest
impact. By eliminating human intervention altogether, autonomous cars
with the proper intelligent infrastructure can reduce road accidents
significantly.

Additionally, autonomous vehicles are believed to have the potential to
shorten travel time and improve traffic flow. They can free up valuable
driving time and enable car owners to complete other tasks while on the
move or merely enjoy the ride.

How will the industry change? Technologically speaking, would a
driverless car look like the cars of today? For instance, in a
completely driverless car, do we need a steering wheel? Companies also
need to think about how other innovations like fuel cells and
nanotechnology can complement such autonomous vehicle even while
reducing the cost.

Whatever the changes the industry can expect, we can safely assume that
the role of ‘intelligence’ within such cars will be significantly
greater than what they are today. Automotive companies must partner with
companies that can help develop, test and implement this intelligence
into the vehicles. Or could this create a new industry by itself?

The automotive industry has already been adapting to this change. It
started with the inclusion and integration of electronics and Artificial
Intelligence into cars.

Next-generation cars include electronics in everything from braking
systems, engine system, power train, body controls to infotainment,
enabled with advanced driver assist systems integrating with multiple
types of sensor inputs, radar and image fusion and analytics. System
architecture, aystem integration and system testing would be more
challenging than ever before.

For autonomous vehicles to become a reality, these requirements will
only increase. What is needed is a more agile automotive ecosystem that
must create and adopt technology faster than before.

— The writer is the head for integrated engineering solutions at Tech Mahindra.

Sunday, 7 July 2013

What is the difference between a pressure transducer and a transmitter

Source: http://www.sensorsone.co.uk/news/24/What-is-the-difference-between-a-pressure-transducer-and-a-transmitter.html

Accessed on: 8th July,2013

29th November 2008
Unfortunately if you are looking for a black and white answer to this question it is not as simple as that. Distinguishing between a pressure transducer and a pressure transmitter can depend upon which country you are working in and which manufacturer you are dealing with. As with a lot of engineering terminology the original definitions have become a little blurred and have not always been used in the way that was originally intended.

A pressure transducer is fundamentally any device that converts an applied pressure into an electrical signal. There have been many different types of pressure transducer developed over the years such as bonded foil, thick film, thin film & semiconductor strain gauge to name just a few. All of these sensing technologies are pressure transducers and they provide an electrical signal typically a millivolt output signal which varies with changes in pressure when connected to an appropriate power supply.

Typically a pressure transducers output signal is one generated by the primary sensing element. Since it is difficult to achieve tight electrical tolerances with the sensing elements during manufacture it is often necessary to add a circuit to trim the zero & span offsets and compensate for errors over the operating temperature range. However the pressure transducer still retains the natural characteristics of the particular sensing technology employed such as linearity, hysteresis, repeatability, stability and frequency response. In fact these are the main reasons for using a pressure transducer which apart from the compensation circuitry are the purest form of pressure sensor.

It is possible to source pressure transducers without compensation electronics which are also known as pressure capsules, modules or headers, which are mostly used by instrument manufacturers who utilise their own micro-electronics to compensate the pressure transducer.
If the electrical connections are short, such as in the laboratory or inside an electronics enclosure the pressure transducer is more desirable, since it is smaller because it has virtually no pcb electronic components inside and there are none or very few active electronic components that can be upset by electromagnetic interference.

So what happens when you want to run the electrical output signal of a pressure transducer over long distances? In the past this was required when engineers started to automate process plants such as power generation plants where they wanted to replace pressure gauges with pressure sensors. The distance was too far between the control system and the measurement point to use a pressure transducer, because the signal losses and interference of the cables would be too great. Therefore the transducer output signal needed to be amplified to transmit the transducer signal over large distances around the plant without attenuation. Many types of amplified signals have been developed over the years as electronics have advanced and power considerations have changed but the 2 wire 4-20mA current loop output has long been accepted worldwide as the main method for transmitting pressure transducer signals over long distances and is still the most requested output signal particularly in the process control industry.

So a pressure transmitter is simply a pressure transducer with some extra electronics to transmit a 4 to 20 mA output signal. At first pressure transmitters would only be found in large process plants and the sensors were bulky and relatively expensive. In recent years other industries have adopted the 4-20mA output signal pressure transmitter because it only needs 2 wire connections and solid-state electronics has shrunk the size and cost of these pressure sensors so much, that it is now difficult to tell the difference between a pressure transducer and transmitter by just looking at its size and shape.
The shrinking of the size of a pressure transmitter is when the definitions started to get blurred between pressure transducers and transmitters. The divisions have become even more blurred with amplified voltage output pressure transducers. They have the signal strength to transmit over greater distances than a strain gauge output pressure transducer but use less power than the 4-20mA output signals.

One of the other benefits of pressure transmitters and high voltage output pressure transducers is that they incorporate zero & span adjustment potentiometers so that the pressure sensors can be easily calibrated.

So today the general rule of thumb is that if the pressure sensor has a millivolt (e.g. 30mV or 100mV) or non-amplified output it is a pressure transducer. If the pressure sensor has a voltage (e.g. 0-5Vdc , 0-10Vdc or 1-5Vdc ) output it is an amplified voltage output pressure transducer. If a pressure sensor has a current loop output (e.g. 2 wire 4-20mA or 3 wire 0 /4-20mA ) it is a pressure transmitter .

However you should be aware that you will find plenty of contradictions to this rule of thumb between manufacturers so always check the actual signal output on the data sheet where there should be no ambiguity and it is best not to rely on the descriptive name to define the output signal.

bar Pressure Unit

Source: http://www.sensorsone.co.uk/pressure-measurement-glossary/bar-pressure-unit.html

Accessed on : 8th July, 2013

The bar is a widely used metric unit of measurement for pressure and 1 bar equals precisely 100,000 Pascals. Even though Bar is not an SI unit it has been adopted as one of the most popular pressure units particularly in European countries where most pressure measurement instruments are specified with pressure ranges in bar.

The value of 1 bar is a close approximation to atmospheric pressure and is often used to represent atmospheric pressure rather than standard atmosphere (101325 Pascals) which is the correct value used by the scientific and engineering community.

Use the following conversion factors to convert from Bar to other pressure units or vice versa. To convert a reading in Bar to another unit, multiply it by the relevant pressure conversion factor. To convert a reading in any pressure unit to Bar divide it by the relevant pressure conversion factor.

Alternatively convert from a bar pressure value into another unit using the bar conversion table or the pressure unit converter.

Bar Pressure Conversion Factors

bar

14.5038

psi

1000

mbar

100000

N/m²

100000

1000

hPa