Archive for January, 2012

Single particle is the smallest Stirling engine yet

January 29th, 2012

The 200-year-old Stirling engine has inspired a power generator made of a single particle just 3 micrometres wide.

Overshadowed by its steam and internal combustion brethren, the Stirling engine is a quiet, efficient alternative that compresses a fixed amount of gas inside a cylinder.

As it is compressed, the gas heats up and expands, pushing a piston, before cooling due to the loss of energy, only to be compressed again.

In their tiny mimic, Clemens Bechinger and Valentin Blickle at the University of Stuttgart, Germany, replaced the cylinder with a laser that confines the motion of a 3-micrometre-wide lump of melamine in water.

Pent-up particle

A zap of heat from another laser builds up tension in this optical “trap”: like a compressed gas, the particle is aching to break free. Widening the trap by modifying the first laser lets it do so, expending the pent-up energy.

“The use of a laser source to provide the required rapid localised heating on the microscopic scale appears to be novel,” says Alan Tucker, leader of the Stirling Cycle Research Group at the University of Canterbury in Christchurch, New Zealand. He calls the technique sophisticated but says that he “struggles” to envision any practical applications. » Read more: Single particle is the smallest Stirling engine yet

What is your dinner doing to the climate?

January 29th, 2012

Local or imported? Conventional or organic? Can you make choices that will keep your diet healthy and reduce your carbon footprint? Is it possible to eat green? Does it even matter?

It may surprise you to learn that our diets account for up to twice as many greenhouse emissions as driving. One recent study suggested that the average US household’s annual carbon food-print is 8.1 tonnes of “equivalent CO2 emissions” or CO2eq (a measure that incorporates any other greenhouse gases produced alongside the CO2). That’s almost twice the 4.4 tonnes of CO2eq emitted by driving a 25-mile-per-US gallon (9 litres per 100 kilometres) vehicle 19,000 km – a typical year’s mileage in the US.

As greenhouse gas emissions attract ever greater scrutiny and criticism, the fields of sustainable consumption and life-cycle carbon accounting have prompted academics to tally the greenhouse gas emissions of hundreds of products and manufacturing processes so …

Climate Change and Ecological Disaster

January 29th, 2012

Global climate change caused by rising concentrations of CO2 in Earth’s atmosphere as the greenhouse effect (greenhouse), industrial activities, the utilization of petroleum and coal resources, and forest fires as the largest contributor of CO2 emissions in the world that lead to changes in environmental and land use (landuse), because of the imbalance between the energy received by the energy released into the air and there is a change order in the atmosphere so that it can affect the cycle becomes unbalanced in nature, resulting in a very significant temperature changes in the atmosphere. Global warming impact on climate change in the world to become unstable, if global warming has continued to increase every year can cause a huge impact on the acceleration of the threat of tropical cyclones such as hurricanes, tidal and flood, extreme temperature rise, tsunami, drought and El Nino may pose a risk of disaster in ecological systems.

Ecological disaster is a natural phenomenon that occurs due to a change in order to experience disturbances on the ecology of several factors that interplay between human beings, living beings and natural conditions. Nature as a place to live and everything that provide a balance of environmental, ecological disasters often occur due to accumulation of the ecological crisis caused by the injustice and the failure of management that resulted in the collapse of the natural order of human life, this condition is also accelerated by the impact made ​​by human activities in managing the environment so affects of global warming on the earth that led to the occurrence of disasters everywhere, the main pengaruhuh of global warming on the occurrence of disasters is the change in air temperature increases resulting in an uneven seasonal changes and triggers the acceleration cycle of geology and meteorology. » Read more: Climate Change and Ecological Disaster