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Near field communication (NFC) is a set of standards for smartphones and similar devices to establish radio communication with each other by touching them together or bringing them into close proximity, usually no more than a few centimetres. Present and anticipated applications include contactless transactions, data exchange, and simplified setup of more complex communications such as Wi-Fi.[1] Communication is also possible between an NFC device and an unpowered NFC chip, called a "tag".[2]

NFC standards cover communications protocols and data exchange formats, and are based on existing radio-frequency identification (RFID) standards including ISO/IEC 14443 and FeliCa.[3] The standards include ISO/IEC 18092[4] and those defined by the NFC Forum, which was founded in 2004 by Nokia, Philips and Sony, and now has more than 160 members. The Forum also promotes NFC and certifies device compliance.[5

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Hicks, R. Andrew, "Designing a Mirror to Realize a Given Projection," J. Opt. Soc. Am. A, vol. 22, No. 2, Feb. 2005

Two military spy telescopes, just as big and powerful as Hubble, donated to NASA

The telescopes were built by private contractors for the National Reconnaissance Office, one of 16 U.S. intelligence agencies. Each have 2.4-meter (7.9-foot) mirrors, just like the Hubble, but they have 100 times the field of view.

the telescopes, built in the late 1990s and early 2000s, are now technologically outdated, at least for intelligence operations, despite being just as powerful as Hubble. Now that something that’s worth taking into consideration. Moreover, these telescopes worth hundreds of millions of dollars have never seen operation! Instead they’ve been shelved in a warehouse somewhere, of course, classified. And they might find themselves, yet again, blocked in a warehouse, since NASA, on a string budget, doesn’t have the necessary cash to fit them.

Newton Papers Plato is my friend, Aristotle is my friend, but my greatest friend is truth." —Sir Isaac Newton

Le LTE (Long Term Evolution) est l'évolution la plus récente des normes de téléphonie mobile : GSM/EDGE, UMTS, CDMA2000 et TD-SCDMA.

La largeur de la bande de fréquences allouée à l’opérateur du réseau. Le débit utile est pratiquement proportionnel à cette largeur de bande (pouvant varier de 1,4 MHz à 20 MHz en LTE, 100 MHz en LTE Advanced).

Les types d’antennes utilisés coté terminal et coté réseau (antenne relais): le débit binaire maximal de 326,4 Mbit/s suppose des antennes MIMO 4X4 (quadruples) aux 2 extrémités de la liaison radio LTE (cas de figure peu réaliste pour un téléphone mobile ou un smartphone). La distance entre le terminal et la (ou les) antennes fixes (le débit est très inférieur en périphérie de cellules radio à cause des interférences avec les cellules adjacentes) et les conditions de réception radio (interférences, bruit, échos liés aux réflexions sur les immeubles, …). Le nombre d’utilisateurs actifs se partageant la bande passante au sein d’une cellule (surface radiante d'une antenne) LTE; plus il y a d’abonnés en communication moins chacun a de débit unitaire. La position fixe (statique) ou « en mouvement » du terminal de l’abonné ; le débit utile est réduit pour un terminal en mouvement. La capacité en débit et en nombre d'utilisateurs simultanés de la station de base (eNode B) et le débit du lien optique reliant cette station au cœur de réseau. Le type et la catégorie du terminal influent aussi sur le débit maximum possible ; par exemple un terminal LTE (en anglais : UE "User Equipment") de catégorie 1, ne supporte qu’un débit binaire de 10 Mbit/s alors qu’un autre de catégorie 3 supportera 100 Mbit/s (voir tableau ci-dessous). En contrepartie, plus la catégorie du terminal est élevée, plus le terminal sera complexe (coûteux) et moins son autonomie sera grande (à niveau technologique égal).

Raspberry Pi An ARM GNU/Linux box for $25.

APC runs a custom Android system, built for keyboard and mouse input. A basic selection of applications is preinstalled. Also included is a full set of consumer I/O ports, enabling APC to connect to your PC monitor or TV.

Volt From Wikipedia, the free encyclopedia Jump to: navigation, search For other uses, see Volt (disambiguation). Josephson junction array chip developed by NIST as a standard volt The volt (symbol: V) is the SI derived unit for electric potential, electric potential difference, and electromotive force.[1] The volt is named in honor of the Italian physicist Alessandro Volta (1745–1827), who invented the voltaic pile, possibly the first chemical battery.

A single volt is defined as the difference in electric potential across a wire when an electric current of one ampere dissipates one watt of power.[

Share Your Sounds Capture a voice, moment or music in seconds or upload audio you’ve already created. Everyone has sounds to share.Now you can share yours.

Light-emitting diode

A light-emitting diode (LED) is a semiconductor light source.[3] LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. Introduced as a practical electronic component in 1962,[4] early LEDs emitted low-intensity red light, but modern versions are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness. When a light-emitting diode is forward-biased (switched on), electrons are able to recombine with electron holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy gap of the semiconductor. LEDs are often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern.[5] LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact fluorescent lamp sources of comparable output. Light-emitting diodes are used in applications as diverse as aviation lighting, automotive lighting, advertising, general lighting, and traffic signals. LEDs have allowed new text, video displays, live video, and sensors to be developed, while their high switching rates are also useful in advanced communications technology. Infrared LEDs are also used in the remote control units of many commercial products including televisions, DVD players, and other domestic appliances.

3D Printing with Sculptris

Sculptris is a supercool free sculpting tool. You can download it here from Pixologic. Much like ZBrush, Sculptris is a solid-body sculpting tool. Since it has an export function, we can use it for 3D printing too! Unfortunately at this stage we don't yet support OBJ files, so there's a couple of easy hoops you need to jump through to get your design ready. First export your sculpt as an OBJ file:

Overview

Tor is a network of virtual tunnels that allows people and groups to improve their privacy and security on the Internet. It also enables software developers to create new communication tools with built-in privacy features. Tor provides the foundation for a range of applications that allow organizations and individuals to share information over public networks without compromising their privacy. Individuals use Tor to keep websites from tracking them and their family members, or to connect to news sites, instant messaging services, or the like when these are blocked by their local Internet providers. Tor's hidden services let users publish web sites and other services without needing to reveal the location of the site. Individuals also use Tor for socially sensitive communication: chat rooms and web forums for rape and abuse survivors, or people with illnesses.