Designed Metasurface Is A Thin, Near Perfect Acoustic Absorber

 

Courtesy of Neomatica:

Physicists from the Hong Kong University of Science and Technology have created a thin metasurface material which functions as a near perfect sound absorber tunable to a desired frequency. Under some conditions more than one frequency is perfectly absorbed. Unlike conventional sound absorbing material that is sometimes only effective when meters thick, the metasurface is deeply “subwavelength” and therefore much thinner.

Current sound absorption materials must be of a thickness comparable to the wavelength of the sounds, which for human hearing ranges from 17 meters to 17 millimeters for low to high frequencies respectively. Low frequency sounds are therefore difficult to damp without many meters of absorbent material.

The new metamaterial relies upon a “decorated membrane resonator” (DMR) which resembles a tiny drum membrane embedded in and coupled to a solid support, in the center of which is a platelet. The dimensions explored by the research team was a membrane 9 cm across, with thickness less than 0.2 mm, holding a platelet in the center 2 cm in diameter. Crucially, the membrane’s elastic modulus must be very low for the harmonics of the metasurface to correspond to the wavelengths of airborne sounds. A reflecting backing then sandwiches a sealed gas layer.

The metasurface exhibits resonance at audible wavelengths such that there is near total absorption of sound, and dissipation of the energy along the lossy membrane.

Nikola Tesla’s Idea of Wireless Transmission of Electrical Energy is a solution for World Energy Crisis

Courtesy of The Tesla Society:

The following are past newspaper articles more than 100 years old which were taken from the Tesla Collection. These are unique original articles about the wireless transmission of electrical energy printed at the time when Tesla was alive.

Articles:

• The New York Journal, Sunday, August 8, 1897 : “Tesla Has Fired the Spark Flashed Round the World”
• New York American, May 22, 1904: Tesla’s Tower – Amazing Scheme of the Great Inventor to Draw Millions of Volts of Electricity Through the Air From Niagara Falls and Then Feed It Out to Cities, Factories and Privat Houses from the Tops of the Towers Without Wires

Above: Nikola Tesla in his laboratory, 1916, in 8th West 40th Street, New York City.

Deep geothermal resource has potential to produce up to 20% of UK electricity and heat for millions

Courtesy of REA.net (2012) but surprisingly no further forward.

A new independent technical report on the potential to generate heat and electricity in the UK from deep geothermal is published today by renowned engineering consultants Sinclair Knight Merz (SKM) [2]. The report features a preface by Dr Ryan Law, Chair of the REA Deep Geothermal Sector Group, and a foreword by Tim Smit, co-founder and Chief Executive, Development, of the Eden Project.

Key findings include:

• The resource is widely spread around the UK with ‘hotspots’ in Cornwall, Weardale, Lake District, East Yorkshire, Lincolnshire, Cheshire, Worcester, Dorset, Hampshire, Northern Ireland and Scotland;
• Cost reduction potential is exceptionally high;
• Deep geothermal resources could provide 9.5GW of baseload renewable electricity – equivalent to nearly nine nuclear power stations – which could generate 20% of the UK’s current annual electricity consumption;
• Deep geothermal resources could provide over 100GW of heat, which could supply sufficient heat to meet the space heating demand in the UK;
• Despite this significant potential, the UK support regime is uncompetitive with other European countries.

The SKM report is published as the geothermal power industry awaits the Renewables Obligation (RO) Banding Review. This will determine whether or not the Coalition Government will back the UK industry. The industry has been shocked by initial proposals to freeze support for deep geothermal power at 2 ROCs, a level too low to stimulate domestic investment. Deep geothermal power is a new technology in the UK and it requires similar support to wave and tidal in its initial development phase. The sector is now growing rapidly internationally and support in the UK must be comparable to other countries in order to attract investment.

On account of the exploration risk inherent with geothermal projects, targeted support at the exploration drilling phase has the potential to stimulate the industry much more cost effectively than a high electricity revenue alone. SKM’s report states that: “risk reduction support is the most critical in developing a cost effective large utilisation of the geothermal resources in the UK. This is particularly needed to enable the early development of sedimentary aquifers for direct heat use as this offers the potential for the most significant and early contribution to meeting the UK commitments to the EU’s Renewable Energy Directive.”

Five things you need to know about: the return of direct current

Courtesy of Andrew Stone @ Performance.com:

How the idea of channeling direct current electricity using circuit breakers could give rise to supergrids.

What is it?

In the early era of electrification, the distribution of electricity by direct current (DC) ruled. Thomas Edison’s first electricity utilities in the late 19th century used DC, but Westinghouse Electric Corporation championed alternating current (AC), developed by Nicola Tesla, which transmits more power more efficiently over longer distances than direct current. Edison did his best to smear the new technology, developing the electric chair as a means of demonstrating the danger of AC and going as far as to electrocute dogs and an elephant, to further illustrate its danger. But to no avail – AC’s superiority was evident and it was soon widely adopted.

Why the renewed interest in DC?

DC has been used since the 1950s to transport electricity at high voltages over distance. In the right application it is more economical and efficient, and suffers fewer power losses. But conversion equipment at terminal stations (transforming high voltage direct current (HVDC) back to AC) is complex and costly, and controlling the flow of power where there are multiple terminals in an HVDC-only network is tricky.These drawbacks have limited HVDC to specific and relatively simple applications that, for example, transfer power between nations using undersea cables or carry power from China’s remote hydropower schemes. But companies including ABB, Alstom and Siemens are competing to show that a much wider application of HVDC is possible. These companies believe an application with new circuit breakers and powered by renewables can be developed. ABB was the first to demonstrate an HVDC circuit breaker in late 2012.

How Electricity Helps Spider Webs Snatch Prey and Pollutants

Courtesy of Science Daily: Spider webs actively spring towards prey thanks to electrically-conductive glue spread across their surface, Oxford University scientists have discovered.

The researchers found that the electrostatic properties of the glue that coats spider webs causes them to reach out to grab all charged particles, from pollen and pollutants to flying insects. They also showed that the glue spirals can distort Earth’s electric field within a few millimetres of the web, which may enable insects to spot the webs with their antennae ‘e-sensors’.

The study, published in Naturwissenschaften, shows how a quirk of physics causes webs to move towards all airborne objects, regardless of whether they are positively or negatively charged. This explains how webs are able to collect small airborne particles so efficiently and why they spring towards insects.

According to the researchers, common garden spider webs around the world could be used for environmental monitoring as they actively filter airborne pollutants with an efficiency comparable to expensive industrial sensors.

NPower and the legal tax avoidance scheme, just a £100 million

NPower Chief executive Paul Massara admitted to MPs earlier this month that NPower had paid no corporation tax since 2008, but he insisted that new capital investments had simply wiped out its profits.

NPower paid just £140 million into the government’s fuel poverty fund while dodging up to £100m in tax, the Morning Star reports.

If you’re thinking of switching Co-op energy is owned by it’s members. It also works to be a lower carbon company that the other suppliers as it sources some energy from community projects, new suppliers etc. In 2011-2012 100% of their energy came from renewables.
Alternatively Ebico is a not-for-profit supplier. They are a little cheaper than the Co-op but they still source their energy from SSE.