Mechanical Engineering

What is nanotechnology?

2007-12-23T23:59:00.000Z

Nanotechnology is a powerful new technology for taking apart and reconstructing nature at the atomic
and molecular level. Nanotechnology is being touted as the basis of the next industrial revolution and
will be used to transform and construct a wide range of new materials, devices, technological systems
and even living organisms.
The term nanotechnology is generally applied to materials, systems and processes that operate at a
scale of 100 nanometres (nm) or less. One nanometre is one billionth of a metre (10-9m). To put
100nm in context: a strand of DNA is 2.5nm wide, a protein molecule is 5nm, a virus particle 150nm, a
red blood cell is 7,000 nm and a human hair is 80,000 nm wide.
The fundamental properties of matter change at the nanoscale. The properties of atoms and
molecules are not governed by the same physical laws as larger objects or even larger particles, but
by “quantum mechanics”. The physical and chemical properties of nanoparticles can therefore be
quite different from those of larger particles of the same substance. Altered properties can include
colour, solubility, material strength, electrical conductivity, magnetic behaviour, mobility (within the
environment and within the human body), chemical reactivity and biological activity1. The altered
properties of nano-sized particles have created new possibilities for profitable products and
applications. However they also introduce serious new risks that remain wholly unregulated.
The excitement around nano is building because people believe that it will bring changes as significant
or potentially more far reaching than those that accompanied the European Industrial revolution.
Proponents and critics alike suggest that nanotechnology will enable break throughs in a wide number
of different fields – communications, agriculture, cognitive science, medicines, military and
environmental remediation to name a few…
“The real power of nanoscale science is the potential to converge disparate technologies that can
operate at this scale. With applications spanning all industry sectors, technological convergence at the
nanoscale is poised to become the strategic platform for global control of manufacturing, food,
agriculture and health in the immediate years ahead”2.
About US$10 billion was spent on nanotechnology research and development in 2004, which is almost
double the money spent in 20033. At least 60 countries have now established publicly funded
nanotechnology research programmes4. Public investment is led by the Japan, US, and EU countries.
Additionally, virtually all of the Fortune Global 500 companies whose business involves manufacturing
are also investing in nanotechnology research.
What are the problems associated with nanotechnology?
_______________________________________________________________________________________________
In the opinion of Friends of the Earth, there are several key problems associated with nanotechnology:
• Serious ethical problems
• Risks to human and environmental safety
• Socio-economic disruption
• A deadly nano arms race
• Erosion of democracy

Serious ethical problems
Ethical problems underlie nanotechnology’s quest to manipulate the very building blocks of life; its
aggressive commercialization enabled by research carried out with public monies, but driven by
commercial and military interests; and the failure of governments to halt the rapid introduction of
nanoproducts and nanomaterials until serious public interest issues are addressed adequately.
Nanobiotechnology raises significant ethical concerns in its quest to engineer organisms and
manufactured products containing both biological and human-made components. The US National
Science Foundation’s work to use convergent nanotechnology, biotechnology, information technology
and cognitive science to improve human performance beyond species-typical boundaries5 is also
particularly ethically problematic. This work has drawn strong criticism from disabilities and human
rights advocates concerned that it will create new inequities and further marginalise existing
disadvantaged groups.
Risks to human and environmental safety
There is a growing body of toxicological evidence that nanoparticles present serious new risks to
human and environmental health6. Leading scientific organisations, including the United Kingdom’s
Royal Society, have warned that the risks of nanotoxicity are serious. In 2004 the Royal Society
recommended that nanomaterials should be treated as new chemicals7 and be subject to new safety
assessments prior to their inclusion in consumer products8. The Royal Society further recommended
that factories and research laboratories should treat nanomaterials as if they were hazardous9, and
until the environmental impacts of nanomaterials are better known, their release into the environment
should be avoided as far as possible10. And yet no government world-wide has introduced a regulatory
system to protect the health of workers, the public and the environment from the risks associated with
nanotoxicity. The Royal Society clearly recommended prohibiting the deliberate release of
nanomaterials for bioremediation until its ecological implications were better understood, and yet this
is already taking place. Concerns surrounding the potential for deliberate or unintentional release of
self-replicating organisms that could cause ecological damage cannot be ruled out.
Socio-economic disruption
Very little attention has been paid to studies of the likely disruptive impacts, and massive job losses,
associated with the expansion of the nanotechnology industry and its displacement of existing
industries. Novel nanomaterials could replace markets for existing commodities, disrupt trade and
eliminate jobs in nearly every industry. Industry analysts Lux Research Inc. have warned that
nanotechnology will result in large-scale disruption to commodity markets and to all supply and value
chains: “Just as the British industrial revolution knocked handspinners and handweavers out of
business, nanotechnology will disrupt a slew of multi billion dollar companies and industries”11. This
would have the most devastating impact on people in the Global South whose countries are
dependent on trade in raw resources (e.g. rubber, cotton, copper) that were displaced by
nanomaterials12. There are clearly profound impacts for labour associated with the promise of
molecular manufacturing systems. In the nearer term, the introduction of nanosensors, along with
increasingly automated production, has the potential to drive down demand for on-farm and
manufacturing labour.
A deadly nano arms race
Nanotechnology will provide the tools for ubiquitous surveillance, with significant implications for civil
liberties. The growing nano arms race may enable a whole new generation of weapons of mass
destruction including nano-biological weaponry. The expansion of nanoweaponry is truly alarming,
especially given the enormous difficulties associated with establishing reliable safeguards against its
use. Retired Admiral David Jeremiah of the US navy believes nanotechnology will prove more
significant than nuclear weapons in determining future political power relations13. Military research and
development is already attracting the lion’s share of nanotechnology funding from the US government,
which is the world’s largest single investor in nanotechnology14. In the 2006 US$1.3billion budget for
the US National Nanotechnology Initiative15, the US Department of Defense received $436 million
(33.5% of the nanotechnology budget). Conversely, only $38.5million (less than 4%) was earmarked

for both the study of the health, safety and environmental impacts of nanotechnology, and also
potential applications in these areas.
Erosion of democracy
Despite the huge transformative potential of nanotechnology, and the billions of dollars of public
funding invested in research and development, there is little transparency in how the decisions
shaping this technology are being made. There has been no effort to engage the public in decision
making about its introduction or regarding how the billions of dollars of public monies should be
invested. Friends of the Earth believes that it is unacceptable that the introduction of such a
transformative new technology should be driven solely by business and political interests, with so
many outstanding questions and without the involvement of the broader community.
Regulatory vacuum
_______________________________________________________________________________________________
Despite the significant risks to human health and the environment posed by nanoparticles, strong calls
for new safety testing from the Royal Society, and the presence of hundreds of products contain
nanomaterials on supermarket shelves, there are still no regulations that specifically relate to
nanotechnology anywhere in the world.
There is still no requirement for nanomaterials to be subject to new safety assessments, no
requirement for product manufacturers to disclose safety testing performed, and no product labelling
to enable consumers to make an informed choice about whether or not they wish to use products
containing nanomaterials. There are no laws in place to regulate occupational exposure and to protect
workers’ health. There are no laws in place to manage environmental releases and to prevent
environmental harm.
Despite throwing its public support (and millions of dollars) behind the nanotech industry, the
Australian government has yet to make any public statement in support of a comprehensive regulatory
regime.
Friends of the Earth are extremely concerned that the response of governments is inadequate to
protect human health or the environment from negative impacts of nanotechnologies.
Nanoproducts – what’s available now
_______________________________________________________________________________________________
Although some people still describe this phase of nano’s commercialisation as being “pre-competitive”,
more than 720 products containing nanomaterials are already available16.
The following list represents just a fraction of the products that are already on the market:
• Transparent sunscreens
• Cosmetics including lipsticks, face
powders, shampoo and moisturisers
• Foods including meal-replacement
milkshakes, canola oil, chewing gum
and food additives
• Temperature moderating, stain,
moisture and odour-repellent clothing
• Agricultural fertilisers
• Long-lasting paints furniture varnishes
and car coatings
• Self-cleaning windows and building
surfaces

Display technology for laptops, mobile
phones, digital cameras
• Football stadium lights
• Metal-cutting tools
• Self-cleaning surfaces for glass and
building surfaces
• Glare-reducing coatings for
eyeglasses and car windscreens
• Automatic catalysts converters
• Bumper bars and step assists for cars
• Tennis balls and racquets
• Dental-binding agents
• Burn and wound dressings
• Bio-imaging products
• Environmental remediation products
• Disinfectants and anti-bacterial
products
• Anti-graffiti coatings for walls

The need for a moratorium
_______________________________________________________________________________________________
Friends of Earth are calling for a moratorium on the further commercial research, development,
production and release of products that contain engineered nanomaterials, until adequate public, peer-
reviewed safety studies have been completed, and adequate regulations have been put in place to
protect the general public, the workers manufacturing these products and the environmental systems
in which waste products will be released.
We also recognise that given the significant implications of nanotechnology for the wider community,
there should be a requirement for public involvement in decision making about its introduction.
References
1 Oberdörster G, Oberdörster E and Oberdörster J (2005). “Nanotoxicology: an emerging discipline from studies of ultrafine particles”. Environmental Health
Perspectives 113(7):823-839
2 p.80 Shand H and Wetter K (2006). “Shrinking Science: an introduction to nanotechnology”. Chapter 5 In State of the World 2006: Special focus: China and
India”. The Worldwatch Institute. WW Norton & Company, New York, USA.
3 Lawrence S (2005). “Nanotech Grows Up”. Technology Review: 108(6)31
4 ETC Group (2005). The potential impact of nanotechnologies on commodity markets: the implications for commodity dependent developing countries. The
South Centre.
5 Roco M and Bainbridge W (Eds) (2002). Converging Technologies for Improving Human Performance: nanotechnology, biotechnology, information
technology and cognitive science. NSF/DOC-sponsored report. Available at: http://www.wtec.org/ConvergingTechnologies/ Accessed 06.03.06
6 See reviews: Oberdörster G, Oberdörster and Oberdörster J (2005). Nanotoxicology: an emerging discipline from studies of ultrafine particles.
Environmental Health Perspectives 113(7):823-839; Hoet P, Bruske-Holfeld I and Salata O (2004). “Nanoparticles – known and unknown health risks”.
Journal of Nanobiotechnology 2:12
7 P85 Recommendation 10, The Royal Society and The Royal Academy of Engineering, UK (2004). Nanoscience and nanotechnologies. Available at
http://www.royalsoc.ac.uk/
8 P86 Recommendation 12 (i), The Royal Society and The Royal Academy of Engineering, UK (2004). Nanoscience and nanotechnologies. Available at
http://www.royalsoc.ac.uk/
9 P85 Recommendation 5 (i), The Royal Society and The Royal Academy of Engineering, UK (2004). Nanoscience and nanotechnologies. Available at
http://www.royalsoc.ac.uk/
10 P85 Recommendation 4, The Royal Society and The Royal Academy of Engineering, UK (2004). Nanoscience and nanotechnologies. Available at
http://www.royalsoc.ac.uk/
11 Cited p22 ETC Group (2004). Down on the farm. Available at: http://www.etcgroup.org
12 Eg see ETC Group (2005). The potential impact of nanotechnologies on commodity markets: the implications for commodity dependent developing
countries. The South Centre.
13 Jeremiah D (1995). “Nanotechnology and global security.” Fourth Foresight conference on molecular nanotechnology. Available at:
http://www.zyvex.com/nanotech/nano4/jeremiahPaper.html
14 Lawrence S (2005). “Nanotech Grows Up”. Technology Review: 108(6)31
15 The National Science and Technology Council (2005). The National Nanotechnology Initiative: Research and development leading to a revolution in
technology and industry. A supplement to the President’s FY 2006 budget. Available at: http://www.nano.gov/NNI_06Budget.pdf
16 Shand H and Wetter K (2006). “Shrinking Science: an introduction to nanotechnology”. Chapter 5 In State of the World 2006: Special focus: China and
India”. The Worldwatch Institute. WW Norton & Company, New York, USA.

http://nano.foe.org.au/

Thermodynamics cycles

2007-06-01T22:10:00.000+01:00

there is a lot of cycle has been produced for sytems in thermodynamics but now some of them are used but a lot of dont used

generally used cycles are:

Brayton cycle:
it is a gas cycle and working fluid is usually air aircraft jet motors are a typically brayton cycles furthermore some electric produce firms uses brayton cycle for their produce.
it is reliable and chip
for more data http://en.wikipedia.org/wiki/Brayton_cycle

rankine cycle:
it is different from brayton cycle because working fluid is generally water this cyle produce more work than brayton but system is bigger than brayton too.it is ideal for power plants
for more data: http://en.wikipedia.org/wiki/Rankine_cycle

stirling and ericson cycles:
this are older cycle than other cycles but generally they cannot be used because some problems
stirling cyle designed for stirling engine which is a external combustion engine.
more material fore stirling http://en.wikipedia.org/wiki/Stirling_engine

Engineering approach

2007-05-29T23:08:00.001+01:00

sometimes calculations are really complex and to be unable to settle or sometimes only complex because of this reasons engineers developed a idea which named as engineering approach.According to engineering approach for example if you calculate heat transfer of patato you have to neglect somethings or you have to accept patato is a water because waters heat transfer rate can be easily calculated than patato and calculated values approximately patatos heat transfer rate if we want to shorten time of calculation or avoid calculation errors we have to use engineering approach but we have to use factor of safety for accidental stuations.

Quenching media during the heat treatment

2007-05-29T16:20:00.000+01:00

quenching media is very important to hardening because it is a very effective of hardness of the material
quenching medias:

Water:
water is fairly good quenching medium.it is cheap,readily available, easily stored nontoxic nonflammable smokeless and easy to filer and pump but with water quench the formation of bubbles may cause soft spots in the metal.Agitation is recommended with use of water quench.Still other problems with waterquench inclued its oxidizing nature,its corrosivity and the tendency to excessive distortion and cracking although this bad properties for plain carbon steels.

Brine (salt water) : Brine is a more severe quench medium than water.Unfortunately it tends to accelerate corrosion problems unless completely removed.Sodium or potasium hydroxide can be used when very severe quenching is desiredand one wishes to obtain good hardness in low carbon steels

Oil: When slower cooling rate is desired oil quenches can be employed.The slower cooling throug the ms to mf temperature range leads to a milder temperature gradient and a reduced likelyhood of cracking.Problems associated with quenchants include water contamination,smoke and fire hazards.in addition quench oils tend to be somewhat expensive.

Air: Low alloy steels in light sections and high alloy steels may be succesfully hardened by means of compressed air or still air.The advantages of using air are that distortion is negligible and that the steel can easily be straigtened during cooling precess.One drawback here is that the surface may be oxidized the cooling.

There is Something About Engineering

2007-05-28T21:38:00.002+01:00

it is well known job, engineering but nobody knows what the engineering means,engineering is art which is collect and mixture art and science in addition engineers have to be economic when they create some work
engineers have to select material which is strong and cheap for instance steel steel is very cheap and strong then other materials in this days a lot of subdivision of industy choose steel for structure
but on the other hand carbon fiber is new and more strong and more light than steel and they can use it on f 1 cars but it is more expensive then steel
finally we can say engineering is art of economy in the industry.

What is mechanical engineering ?

2007-05-28T21:38:00.001+01:00

Mechanical engineering is concerned with the design, construction, and operation of power plants, engines, and machines. It deals mostly with things that move. One common way of dividing mechanical engineering is into heat utilization and machine design. The generation, distribution, and use of heat is applied in boilers, heat engines, air conditioning, and refrigeration. Machine design is concerned with hardware, including that making use of heat processes.

Factor Of Safety

2007-05-28T21:37:00.002+01:00

factor of safety is very importan thing for engineers and all engineers use this factor for their projects.But what is factor of safety ?
engineers use very useful calculation for their projects but everytime they have to neglect somethings for example transverse shear for strength of materials or air resistance for some aerodynamics calculation and sometimes they use some materials but the material!s properties can be changeble because of this reasons mechanical engineers use factor of safety. but how ve can calculate factor of safety it is so easy first of all the calculations done and then make a decision for factor of safety value for example 1.8 is food value for strength of materials applications if we made calculation and we have found for example 100 mpa then we will divide it with 1.8 and we can find new value
new value=calculated value/f.s

Heat Treatment

2007-05-28T21:37:00.001+01:00

Heat treatment is the controlled heating and cooling of metals for the purpose of altering their properties because both mechanical and physical properties can be alterede by heat treatment and it is one of the most important and widely used manifacturing processes.the designer who select material and the engineer who determines its processing must be aware of the possible changes in properties.

some heat treatments for steel are;

spheroidizing annel
recyrstallization annealing
stress relief annealing
full annealing
normalizing

and if you want to see annealing temperatures on carbon-temperature diagram ;

Quenching

2007-05-28T21:36:00.001+01:00

the rapid cooling necessary to harden a steel is known as quenchingand the liquid in to which the steel is immersed to promote this rapid cooling is called the quenching bath. heat tratment process consists of heating the steel to a temperature just above its critical point holding the metal at this temperature for suffcient time then quenching it by using a suitable quenching bath.
some quenching methods are;
direct quenching to martensite:
the first quenching method was direct quenching.according to this method the steel is cooled or quenched directly from hardening temperature to the room temperature the cooling medium is usually water sometimes oil and sometimes air.this method has some big disadvantages a most important disadvantage is distortions because of temperature differance in center of material with surface of the material.
martempering:
in this treatment the cooling takes place in two stages fist tool quenched in a molten salt bath,kept at a temperature somewhat above that at which the austenitic structure of the steel starts to transform to martenzite.the steel is held there until temperature equalization is complate than it is allowed to cool freely in air.the advantage of this method is less residual stresses and distortions than direct quenching but it has a big disadvantage this method can not be usable for all kind of materials.after the this process you have to do tempering
austempering:
it is an isothermal heat treatment which produces a bainite structure in some plain carbon steels.it is an alternative procedure to quenching and tempering for increasing the thoughness and ductility of some steels it likes martempering but it has some differences; first material quenched in salt bath to the temperature which is kept above the matersite formation.keeping time has to sufficient for austenine to completely transformed to bainite.the materials which cabaple being martempered also be austempered.because of long time for complate transformation the high alloy steels are not capable for being austempered.austempering usually improves ductilitiy and impact resistance of certain steels over those values obtained by direct quenching and tempering.it also causes decreased distortion of the quenched material.