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Piezoelectricity

Piezoelectricity
A piezoelectric system (without contact tabs) Piezoelectricity is found in useful applications such as the production and detection of sound, generation of high voltages, electronic frequency generation, microbalances, and ultrafine focusing of optical assemblies. It is also the basis of a number of scientific instrumental techniques with atomic resolution, the scanning probe microscopies such as STM, AFM, MTA, SNOM, etc., and everyday uses such as acting as the ignition source for cigarette lighters and push-start propane barbecues. History[edit] Discovery and early research[edit] The pyroelectric effect, by which a material generates an electric potential in response to a temperature change, was studied by Carl Linnaeus and Franz Aepinus in the mid-18th century. A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated) The Curies, however, did not predict the converse piezoelectric effect. World War I and post-war[edit] World War II and post-war[edit] Related:  Wikipedia 2Lohr, Jenny, Science, and Awesome

Oxide Ceramics – Piezo-ceramics Piezo-ceramic materials are categorized as functional ceramics. In sensors they make it possible to convert forces, pressures and accelerations into electrical signals, and in sonic and ultrasonic transducers and actuators they convert electric voltages into vibrations or deformations. Piezo-ceramic materials are classified according to their chemical composition on the one hand, and by the specific application conditions on the other. CeramTec distinguishes between the following material categories: Materials for power transducers (ultrasonic applications) Materials for sensors (ultrasonic transmitters and receivers) Materials for actuators (precision positioning or injection systems) Materials for special applications Contacting of the metalized piezo-ceramics can be made using conductive adhesives, conductive rubbers, spring contacts or via soldering.

Preparation of Rochelle Salt (Potassium Sodium Tartrate) Here you will learn how to prepare Rochelle salt from baking soda and cream of tartar, which are available from a grocery store. Here's what you need 500 g (1 lb) of baking soda (sodium bicarbonate)[NaHCO3] 200 g (7 oz) of cream of tartar (potassium bitartrate)[KHC4H4O6] [see note below] Oven Pyrex container Jar with lid 500 mL (2 cup) glass beaker or Pyrex measuring cup Sauce pan with water 2 mL (1/2 tsp) measuring spoon Spoon for stirring Coffee Filter Filter paper or paper towelling NOTE: Some people have gone to bulk food or health food stores where they found a less expensive cream of tartar. Unfortunately, what is sold there as "cream of tartar" frequently has been NOT potassium bitartrate, but rather a mixture of calcium sulfate (Plaster of Paris), monocalcium phosphate, fumaric acid, and corn starch. This mixture definitely WILL NOT WORK. Here's what you do for the first reaction Place the contents of a 500 g box of baking soda into a suitable Pyrex container.

Wind Turbine Design – The Most Amazing Windmills in the World | A journey through the evolution of the most spectacular wind turbines designs in the world - Looking for an environmentally friendly energy source while looking gracious, aesthetic and beautiful? The answer is blowing in the wind! Below is a selection of pictures and descriptions of some of the most spectacular & truly ambitious wind turbine designs of this millennium…whose scope & promise could pave the way for much greater harnessing of wind energy. We are starting this picture series with a small selection of beautiful images of historical and traditional wind mill and wind turbine designs and will finish with the most spectacular high tech inventions of this century. Wind Turbine 1888 by Charles Brush Charles F. “I hear the howl of the wind that brings The long drear storm on its heavy wings” William Cullen Bryant Super-Windmills Further, it went that ‘The next few years might see a great change in the landscape of our country. Victor Hugo Classic ‘Dutch Style’ Wind Mills [ad] Wind! Leo F.

Van der Waals force In physical chemistry, the van der Waals' force (or van der Waals' interaction), named after Dutch scientist Johannes Diderik van der Waals, is the sum of the attractive or repulsive forces between molecules (or between parts of the same molecule) other than those due to covalent bonds, the hydrogen bonds, or the electrostatic interaction of ions with one another or with neutral molecules or charged molecules.[1] The term includes: force between two permanent dipoles (Keesom force)force between a permanent dipole and a corresponding induced dipole (Debye force)force between two instantaneously induced dipoles (London dispersion force). It is also sometimes used loosely as a synonym for the totality of intermolecular forces. Van der Waals' forces are relatively weak compared to covalent bonds, but play a fundamental role in fields as diverse as supramolecular chemistry, structural biology, polymer science, nanotechnology, surface science, and condensed matter physics. Definition[edit] .

Piezoelectricity Crystals which acquire a charge when compressed, twisted or distorted are said to be piezoelectric. This provides a convenient transducer effect between electrical and mechanical oscillations. Quartz demonstrates this property and is extremely stable. Quartz crystals are used for watch crystals and for precise frequency reference crystals for radio transmitters. Rochelle salt produces a comparatively large voltage upon compression and was used in early crystal microphones. The word piezo is Greek for "push". There is a magnetic analog where ferromagnetic material respond mechanically to magnetic fields. Cymatics Resonance made visible with black seeds on a harpsichord soundboard Cornstarch and water solution under the influence of sine wave vibration Cymatics (from Greek: κῦμα "wave") is the study of visible sound co vibration, a subset of modal phenomena. Typically the surface of a plate, diaphragm, or membrane is vibrated, and regions of maximum and minimum displacement are made visible in a thin coating of particles, paste, or liquid.[1] Different patterns emerge in the excitatory medium depending on the geometry of the plate and the driving frequency. The apparatus employed can be simple, such as the old Chinese spouting bowl, or Chinese singing fountain, in which copper handles are rubbed and cause the copper bottom elements to vibrate. Etymology[edit] History[edit] On July 8, 1680, Robert Hooke was able to see the nodal patterns associated with the modes of vibration of glass plates. Influences in art[edit] Composer Stuart Mitchell and his father T.J. Influences in engineering[edit]

Summary: Neighbourhood or community group purchase and distribution of energy saving equipment | Community Pathways Installation or use of energy saving equipment reduces household's energy bills as well as reducing their carbon emissions. Providing community members directly with the physical means to improve the energy efficiency of their homes overcomes barriers of inertia and feelings of hassle, which enables them to take action. At the same time, working together on a shared agenda strengthens social norms, which can reinforce the low carbon activities being undertaken, and increase the potential for future actions. Purchasing in bulk may also be a way to get discounts, or at least an efficient way to seek 'best buys' on behalf of the community. It may also be more effective as a group to seek funding than as separate individuals, for example from energy suppliers or other commercial bodies with new products to promote or environmental or social objectives and targets to meet.

Feudalisme Feudalisme (af senlatin feudum, afled af feuda, det vil sige len), betegner en samfundsordning med et stykke land, som feodati = "vasaller" har brugsretten til under bestemte vilkår. Ordet feudum kom i brug i løbet af middelalderen, mens feudalisme som beskrivelse af en samfundsorden først blev skabt i det 17. århundrede. I dansk historisk litteratur kaldes feudalisme ofte for lensvæsen. Dette system havde ikke en særlig betegnelse i middelalderen, og feudalisme opstod først senere som begreb for at beskrive en praksis, der ikke længere blev brugt. Feudalisme som begreb blev et almindeligt brugt historisk tema, dog ofte med en vis nedsættende klang.[1] Den oprindelige snævre betydning af dette begreb var en beskrivelse af en samfundsform, hvor løfter om krigstjeneste blev udvekslet med jord i et hierarkisk system inden for samfundets elite. Siden er begrebet bl.a. blevet brugt af historikere og andre til at beskrive det middelalderlige samfund generelt. Clifford R.

Accuracy and reliability of forensic latent fingerprint decisions Property law The concept, idea or philosophy of property underlies all property law. In some jurisdictions, historically all property was owned by the monarch and it devolved through feudal land tenure or other feudal systems of loyalty and fealty. Though the Napoleonic code was among the first government acts of modern times to introduce the notion of absolute ownership into statute, protection of personal property rights was present in medieval Islamic law and jurisprudence,[1] and in more feudalist forms in the common law courts of medieval and early modern England. Theory[edit] The word property, in everyday usage, refers to an object (or objects) owned by a person — a car, a book, or a cellphone — and the relationship the person has to it. Early American theory[edit] James Wilson, U.S. In the opening sentence of "On the History of Property," he states quite clearly: “Property is the right or lawful power, which a person has to a thing.” Property rights and rights to people[edit] Possession[edit]

Energy Purchase & Sales — Community Renewable Energy A community renewable developer can recoup some, if not all, of its costs by entering into agreements with utilities to purchase the output of the project. In addition to energy, a utility may place value on, and hence be willing to pay for, capacity, identified distribution or transmission benefits, and environmental benefits. Some typical arrangements are described in more detail below. For more on the value of renewables to utilities, click here. Power Purchase Agreements Power Purchase Agreements (PPAs) are legal contracts between buyers and sellers of energy and capacity, and specify important details of the transaction, including the term of the contract and price paid for energy. When negotiating a PPA, environmental attributes, often called Green Tags or Renewable Energy Credits are usually sold with the power, but this must be specified in the PPA or it will be assumed that they are owned by the project owner. PURPA and Avoided Costs Net Metering

Manufacturing Consent Manufacturing Consent: The Political Economy of the Mass Media is a 1988 non-fiction book co-written by Edward S. Herman and Noam Chomsky, wherein the authors argue that the mass media of the United States "are effective and powerful ideological institutions that carry out a system-supportive propaganda function by reliance on market forces, internalized assumptions, and self-censorship, and without overt coercion".[1] Government and news media[edit] Editorial distortion is aggravated by the news media’s dependence upon private and governmental news sources. If a given newspaper, television station, magazine, etc., incurs governmental disfavor, it is subtly excluded from access to information. Consequently, it loses readers or viewers, and ultimately, advertisers. Editorial bias: five filters[edit] Herman and Chomsky's "propaganda model" describes five editorially distorting filters applied to news reporting in mass media: Recent developments[edit] See also[edit] References[edit]

Reliability-of-Fingerprint-Evidence As a general proposition, fingerprint experts believe that fingerprint patterns never change and are unique to each individual. For this reason, state and federal judges do not usually question their evidentiary validity. Juries typically agree when such evidence suggests an individual is guilty of committing a crime. At times, such evidence is so convincing that individuals accused of crimes confess when confronted with a "match." Despite the widespread acceptance of fingerprint evidence, many question its worth due to a significant amount of identification mistakes. Lack of Uniform Standards for Fingerprint Analysis Mistakes in identification may occur because the actual determination of a match is based on human inspection, a process many deem to be an imperfect science. The Scientific Working Group on Friction Ridge Analysis, Study, and Technology (SWGFAST), another recognized fingerprint organization, sets forth standards to assure quality fingerprint examination.

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