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Wednesday, June 26, 2019

Brain Computer Interface



brain–computer interface (BCI), sometimes called a neural-control interface (NCI), mind-machine interface (MMI), direct neural interface (DNI), or brain–machine interface (BMI), is a direct communication pathway between an enhanced or wired brain and an external device. BCI differs from neuromodulation in that it allows for bidirectional information flow. BCIs are often directed at researching, mapping, assisting, augmenting, or repairing human cognitive or sensory-motor functions.

Research on BCIs began in the 1970s at the University of California, Los Angeles (UCLA) under a grant from the National Science Foundation, followed by a contract from DARPA. The papers published after this research also mark the first appearance of the expression brain–computer interface in scientific literature.

The field of BCI research and development has since focused primarily on neuroprosthetics applications that aim at restoring damaged hearing, sight and movement. Thanks to the remarkable cortical plasticity of the brain, signals from implanted prostheses can, after adaptation, be handled by the brain like natural sensor or effector channels. Following years of animal experimentation, the first neuroprosthetic devices implanted in humans appeared in the mid-1990s.

Tuesday, June 25, 2019

Hydroelectric Dams


Hydroelectric dams with large reservoirs can also be operated to provide peak generation at times of peak demand. Water is stored in the reservoir during periods of low demand and released through the plant when demand is higher. The net effect is the same as pumped storage, but without the pumping loss. Depending on the reservoir capacity the plant can provide daily, weekly, or seasonal load following. Many existing hydroelectric dams are fairly old (for example, the Hoover Dam was built in the 1930s), and their original design predated the newer intermittent power sources such as wind and solar by decades. A hydroelectric dam originally built to provide baseload power will have its generators sized according to the average flow of water into the reservoir. Uprating such a dam with additional generators increases its peak power output capacity, thereby increasing its capacity to operate as a virtual grid energy storage unit.

 The United States Bureau of Reclamation reports an investment cost of $69 per kilowatt capacity to uprate an existing dam,  compared to more than $400 per kilowatt for oil-fired peaking generators. While an uprated hydroelectric dam does not directly store excess energy from other generating units, it behaves equivalently by accumulating its own fuel – incoming river water – during periods of high output from other generating units. Functioning as a virtual grid storage unit in this way, the uprated dam is one of the most efficient forms of energy storage, because it has no pumping losses to fill its reservoir, only increased losses to evaporation and leakage.

A dam which impounds a large reservoir can store and release a correspondingly large amount of energy, by controlling river outflow and raising or lowering its reservoir level a few meters. Limitations do apply to dam operation, their releases are commonly subject to government regulated water rights to limit downstream effect on rivers. For example, there are grid situations where baseload thermal plants, nuclear or wind turbines are already producing excess power at night, dams are still required to release enough water to maintain adequate river levels, whether electricity is generated or not. Conversely there's a limit to peak capacity, which if excessive could cause a river to flood for a few hours each day.


Small Satellite


Small satellitesminiaturized satellites, or smallsats, are satellites of low mass and size, usually under 500 kg (1,100 lb). While all such satellites can be referred to as "small", different classifications are used to categorize them based on mass. Satellites can be built small to reduce the large economic cost of launch vehicles and the costs associated with construction. Miniature satellites, especially in large numbers, may be more useful than fewer, larger ones for some purposes – for example, gathering of scientific data and radio relay. Technical challenges in the construction of small satellites may include the lack of sufficient power storage or of room for a propulsion system.


The Nano satellite and microsatellite segments of the satellite launch industry have been growing rapidly in recent years, and were based on the Spanish low cost manufacturing for Commercial and Communication Satellites from the 1990s. Development activity in the 1–50 kg (2.2–110.2 lb) range has been significantly exceeding that in the 50–100 kg (110–220 lb) range. European analyst Euro consult projects more than 500 smallsats being launched in the years 2015–2019 with a market value estimated at US$7.4 billion. By mid-2015, many more launch options had become available for smallsats, and rides as secondary payloads had become both greater in quantity and with the ability to schedule on shorter notice.
               
Although smallsats have traditionally been launched as secondary payloads on larger launch vehicles, there are a number of companies currently developing launch vehicles specifically targeted at the smallsat market. In particular, the secondary payload paradigm does not provide the specificity required for many small satellites that have unique orbital and launch-timing requirements. Small satellite_examples_include DemeterEssaimParasolPicardMICROSCOPETARANISELISASSOTSMART-1, and Spirale-A and -B.


Monday, June 24, 2019

Lithium Iron Phosphate Battery


The lithium iron phosphate battery (LiFePO4 battery) or LFP battery (lithium Ferro phosphate), is a type of rechargeable battery, specifically a lithium-ion battery, using LiFePO4 as the cathode material, and a graphitic carbon electrode with a metallic backing as the anode. The specific capacity of LiFePO4 is higher than that of the related lithium cobalt oxide (LiCoO2) chemistry, but its density is less due to its lower operating voltage. The main drawback of LiFePO4 is its low electrical conductivity. Therefore, all the LiFePO4 cathodes under consideration are actually LiFePO4/C. Because of low cost, low toxicity, well-defined performance, long-term stability, etc. LiFePO4 is finding a number of roles in vehicle use, utility scale stationary applications, and backup power.


Lithium Iron Phosphate LiFePO4, each Cells 700 Ah Amp Hours 3.25 Volts. Two cells are wired in parallel to create a single 3.25V 1400Ah cell, with a capacity of 4,550 Watt hours or 4.55 kWh. Note the multi-layer copper bus bar designed to carry more electrons on the surface of multiple plates rather than using a single solid connector between cells. Higher discharge rates needed for acceleration, lower weight and longer life makes this battery type ideal for bicycles and electric cars. 12V LiFePO4 batteries are also getting popularity as a second (house) battery for a caravan, motor-home or boat.


LiFePO4-powered solar lamps are visibly brighter than ubiquitous outdoor solar lights, and performance overall is considered more reliable. Many home EV conversions use the large format versions as the car's traction pack. With the efficient power-to-weight ratios, high safety features and the chemistry's resistance to thermal runaway, there are few barriers for use by amateur home "makers". Motorhomes are often converted to lithium iron phosphate because of the high draw. Some electronic cigarettes use these types of batteries. Other applications include flashlights, radio-controlled models, portable motor-driven equipment, industrial sensor systems and emergency lighting


Home Fuel Cell


home fuel cell or a residential fuel cell is a scaled down version of industrial stationary fuel cell for primary or backup power generation. These fuel cells are usually based on combined heat and power-CHP or micro combined heat and power MicroCHP technology, generating both power and heated water or air. A commercially working cell is called Ene-Farm in Japan and is supported by the regional government which uses natural gas to power up the fuel cell to produce electricity and heated water. Most home fuel cells fit either inside a mechanical room or outside a home or business, and can be discreetly sited to fit within a building's design.

            Some of the newer home fuel cells can generate anywhere between 1–5 kW—optimal for larger homes (370 square metres [4,000 sq ft] or more), especially if pools, spas, and radiant floor heating are in plans. Other uses include sourcing of back-up power for essential loads like refrigerator/freezers and electronics/computers. Deploying the system's heat energy efficiently to a home or business' hot water applications displaces the electricity or gas otherwise burned to create that heat, which further reduces overall energy bills. Retail outlets like fast food chains, coffee bars, and health clubs gain operational savings from hot water heating.


Since it is in general not possible for a fuel cell to produce at all times exactly the needed amount of both electricity and heat, home fuel cells are typically not standalone installations. Instead they may rely on the grid when the electricity production is above or below what is needed. Additionally, a home fuel cell may be combined with a traditional furnace that produces only heat. For example, the German company Viessmann produces a home fuel cell with an electric power of 0.75 kW and a thermal power of 1 kW, integrated with a traditional 19 kW heat producing furnace, using the grid for electricity need below and above the fuel cell production.

Sunday, June 23, 2019

Radio-Frequency Identification



Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. The tags contain electronically stored information. Passive tags collect energy from a nearby RFID reader's interrogating radio waves. Active tags have a local power source (such as a battery) and may operate hundreds of meters from the RFID reader. Unlike a barcode, the tag need not be within the line of sight of the reader, so it may be embedded in the tracked object. RFID is one method of automatic identification and data capture (AIDC).  RFID tags are used in many industries.

 For example, an RFID tag attached to an automobile during production can be used to track its progress through the assembly line; RFID-tagged pharmaceuticals can be tracked through warehouses; and implanting RFID microchips in livestock and pets enables positive identification of animals. Since RFID tags can be attached to cash, clothing, and possessions, or implanted in animals and people, the possibility of reading personally-linked information without consent has raised serious privacy concerns. These concerns resulted in standard specifications development addressing privacy and security issues. ISO/IEC 18000 and ISO/IEC 29167 use on chip cryptography methods for untraceability, tag and reader authentication, and over-the-air privacy. 

ISO/IEC 20248 specifies a digital signature data structure for RFID and barcodes providing data, source and read method authenticity. This work is done within ISO/IEC JTC 1/SC 31 Automatic identification and data capture techniques. Tags can also be used in shops to expedite checkout, and to prevent theft by customers and employees. In 2014, the world RFID market was worth US$8.89 billion, up from US$7.77 billion in 2013 and US$6.96 billion in 2012. This figure includes tags, readers, and software/services for RFID cards, labels, fobs, and all other form factors. The market value is expected to rise to US$18.68 billion by 2026.


Flywheel Storage


Mechanical inertia is the basis of this storage method. When the electric power flows into the device, an electric motor accelerates a heavy rotating disc. The motor acts as a generator when the flow of power is reversed, slowing down the disc and producing electricity. Electricity is stored as the kinetic energy of the disc. Friction must be kept to a minimum to prolong the storage time. This is often achieved by placing the flywheel in a vacuum and using magnetic bearings, tending to make the method expensive. Greater flywheel speeds allow greater storage capacity but require strong materials such as steel or composite materials to resist the centrifugal forces.

            The ranges of power and energy storage technology that make this method economic, however, tends to make flywheels unsuitable for general power system application; they are probably best suited to load-leveling applications on railway power systems and for improving power quality in renewable energysystems such as the 20MW system in Ireland.  Applications that use flywheel storage are those that require very high bursts of power for very short durations such as tokamak and lase rexperiments where a motor generator is spun up to operating speed and is partially slowed down during discharge.

 Flywheel storage is also currently used in the form of the Diesel rotary uninterruptible power supply to provide uninterruptible power supplysystems (such as those in large datacenters) for ride-through power necessary during transfer – that is, the relatively brief amount of time between a loss of power to the mains and the warm-up of an alternate source, such as a diesel generator. Powercorp in Australia have been developing applications using wind turbines, flywheels and low load diesel (LLD) technology to maximize the wind input to small grids. A system installed in Coral Bay, Western Australia, uses wind turbines coupled with a flywheel based control system and LLDs. The flywheel technology enables the wind turbines to supply up to 95 percent of Coral Bay's energy supply at times, with a total annual wind penetration of 45 percent.


Saturday, June 22, 2019

Electric Vehicles


Companies are researching the possible use of electric vehicles to meet peak demand. A parked and plugged-in electric vehicle could sell the electricity from the battery during peak loads and charge either during night (at home) or during off-peak.Plug-in hybrid or electric cars could be used  for their energy storage capabilities. Vehicle-to-grid technology can be employed, turning each vehicle with its 20 to 50 kWh battery pack into a distributed load-balancing device or emergency power source.

This represents 2 to 5 days per vehicle of average household requirements of 10 kWh per day, assuming annual consumption of 3650 kWh. This quantity of energy is equivalent to between 40 and 300 miles (64 and 483 km) of range in such vehicles consuming 0.5 to 0.16 kWh per mile. These figures can be achieved even in home-made electric vehicle conversions. Some electric utilities plan to use old plug-in vehicle batteries (sometimes resulting in a giant battery) to store electricity However, a large disadvantage of using vehicle to grid energy storage would be if each storage cycle stressed the battery with one complete charge-discharge cycle. 

However, one major study showed that used intelligently, vehicle-to-grid storage actually improved the batteries longevity. Conventional (cobalt-based) lithium ion batteries break down with the number of cycles – newer li-ion batteries do not break down significantly with each cycle, and so have much longer lives. One approach is to reuse unreliable vehicle batteries in dedicated grid storage as they are expected to be good in this role for ten years. If such storage is done on a large scale it becomes much easier to guarantee replacement of a vehicle battery degraded in mobile use, as the old battery has value and immediate use.

Lithium–Air Battery


The lithium–air battery (Li–air) is a metal–air electrochemical cell or battery chemistry the uses oxidation of lithium at the anode and reduction of oxygen at the cathode to induce a current flow. Pairing lithium and ambient oxygen can theoretically lead to electrochemical cells with the highest possible specific energy. Indeed, the theoretical specific energy of a non-aqueous Li–air battery, in the charged state with Li2O2 product and excluding the oxygen masks, is ~40.1 MJ/kg. This is comparable to the theoretical specific energy of gasoline, ~46.8 MJ/kg. In practice, Li–air batteries with a specific energy of ~6.12 MJ/kg at the cell level have been demonstrated. This is about 5 times greater than that of a commercial lithium-ion battery, and is sufficient to run a 2,000 kg EV for ~500 km (310 miles) on one charge using 60 kg of batteries.

 However, the practical power and life-cycle of Li–air batteries need significant improvements before they can find a market niche. Significant electrolyte advances are needed to develop a commercial implementation. Four approaches are active: aproticaqueoussolid state and mixed aqueous–aprotic. Metal–air batteries, specifically zinc–air, have received attention due to potentially high energy densities. The theoretical specific energy densities for metal–air batteries are higher than for ion-based methods. Lithium–air batteries can theoretically achieve 3840 mA·h/g.

A major market driver for batteries is the automotive sector. The energy density of gasoline is approximately 13 Kw h/kg, which corresponds to 1.7 kW·h/kg of energy provided to the wheels after losses. Theoretically, lithium–air can achieve 12 kW·h/kg (43.2 MJ/kg) excluding the oxygen mass. Accounting for the weight of the full battery pack (casing, air channels, lithium substrate), while lithium alone is very light, the energy density is considerably lower. A Li–air battery potentially had 5–15 times the specific energy of a Li-ion battery.

Pumped Water


In 2008 world pumped storage generating capacity was 104 GW, while other sources claim 127 GW, which comprises the vast majority of all types of grid electric storage – all other types combined are some hundreds of MW.  In many places, pumped storage hydroelectricity is used to even out the daily generating load, by pumping water to a high storage reservoir during off-peak hours and weekends, using the excess base-load capacity from coal or nuclear sources. During peak hours, this water can be used for hydroelectric generation, often as a high value rapid-response reserve to cover transient peaks in demand. Pumped storage recovers about 70% to 85% of the energy consumed, and is currently the most cost effective form of mass power storage. The chief problem with pumped storage is that it usually requires two nearby reservoirs at considerably different heights, and often requires considerable capital expenditure.

Pumped water systems have high dispatchability, meaning they can come on-line very quickly, typically within 15 seconds, which makes these systems very efficient at soaking up variability in electrical demand from consumers. There is over 90 GW of pumped storage in operation around the world, which is about 3% of instantaneous global generation capacity. Pumped water storage systems, such as the Dinorwig storage system in Britain, hold five or six hours of generating capacity, and are used to smooth out demand variations. Another example is the 1836 MW Tianhuangping Pumped-Storage Hydro Plant in China, which has a reservoir capacity of eight million cubic meters (2.1 billion U.S. gallons or the volume of water over Niagara Falls in 25 minutes) with a vertical distance of 600 m (1970 feet).

 The reservoir can provide about 13 GW·h of stored gravitational potential energy (convertible to electricity at about 80% efficiency), or about 2% of China's daily electricity consumption. A new concept in pumped-storage is utilizing wind energy or solar power to pump water. Wind turbines or solar cells that direct drive water pumps for an energy storing wind or solar dam can make this a more efficient process but are limited. Such systems can only increase kinetic water volume during windy and daylight periods.

Thursday, June 20, 2019

Airborne wind turbine


An airborne wind turbine is a design concept for a wind turbine with a rotor supported in the air without a tower, thus benefiting from more mechanical and aerodynamic options, the higher velocity and persistence of wind at high altitudes, while avoiding the expense of tower construction, or the need for slip rings or yaw mechanism. An electrical generator may be on the ground or airborne. Challenges include safely suspending and maintaining turbines hundreds of meters off the ground in high winds and storms, transferring the harvested and/or generated power back to earth, and interference with aviation.

Airborne wind turbines may operate in low or high altitudes; they are part of a wider class of Airborne Wind Energy Systems (AWES) addressed by high-altitude wind power and crosswind kite power. When the generator is on the ground, then the tethered aircraft need not carry the generator mass or have a conductive tether. When the generator is aloft, then a conductive tether would be used to transmit energy to the ground or used aloft or beamed to receivers using microwave or laser.

 Kites and helicopters come down when there is insufficient wind; kytoons and blimps may resolve the matter with other disadvantages. Also, bad weather such as lightning or thunderstorms, could temporarily suspend use of the machines, probably requiring them to be brought back down to the ground and covered. Some schemes require a long power cable and, if the turbine is high enough, a prohibited airspace zone.


Magnesium Battery


Magnesium batteries are batteries that utilize magnesium cations as the active charge transporting agent in solution and as the elemental anode of an electrochemical cell. Both non-rechargeable primary cell and rechargeable secondary cell chemistries have been investigated. Magnesium primary cell batteries have been commercialised and have found use as reserve and general use batteries. Primary magnesium cells have been developed since the early 20th century. A number of chemistries for reserve battery types have been researched, with cathode materials including silver chloridecopper(I) chloridepalladium(II) chloridecopper(I) iodidecopper(I) thiocyanatemanganese dioxide and air (oxygen). For example, a water activated silver chloride/magnesium reserve battery became commercially available by 1943.

 Magnesium secondary cell batteries are an active topic of research, specifically as a possible replacement or improvement over lithium-ion–based battery chemistries in certain applications. A significant advantage of magnesium cells is their use of a solid magnesium anode, allowing a higher energy density cell design than that made with lithium, which in many instances requires an intercalated lithium anode. Insertion type anodes ('magnesium ion') have also been researched, primarily as heavy main group metal thin films or as Zintl phases, for instance Mg2Sn.

A magnesium–air fuel cell has theoretical operating voltages of 3.1 V and energy densities of 6.8 kwh/kg. General Electric produced a magnesium air fuel cell operating in neutral NaCl solution as early as the 1960s. The magnesium air battery is a primary cell, but has the potential to be 'refuelable' by replacement of the anode and electrolyte. Magnesium air batteries have been commercialised and find use as land based backup systems as well as undersea power sources, using seawater as the electrolyte.

Monday, June 10, 2019

Electrothermal-Chemical Technology


Electrothermal-chemical (ETC) technology is an attempt to increase accuracy and muzzle energy of future tankartillery, and close-in weapon system guns by improving the predictability and rate of expansion of propellants inside the barrel. An electrothermal-chemical gun uses a plasma cartridge to ignite and control the ammunition's propellant, using electrical energy to trigger the process. ETC increases the performance of conventional solid propellants, reduces the effect of temperature on propellant expansion and allows for more advanced, higher density propellants to be used.

The technology has been under development since the mid-1980s and at present is actively being researched in the United States by the Army Research LaboratorySandia National Laboratories and defense industry contractors, including FMC CorporationGeneral Dynamics Land SystemsOlin Ordnance, and Soreq Nuclear Research Center. It is possible that electrothermal-chemical gun propulsion will be an integral part of US Army's future combat system and those of other countries such as Germany and the United Kingdom. ETC technology offers a medium-risk upgrade and is developed to the point that further improvements are so minor that it can be considered mature.

Nevertheless, there is substantial existing evidence that ETC technology is viable and worth the money to continue development. Furthermore, it can be integrated into current gun systems. ETC increases the performance of conventional solid propellants, reduces the effect of temperature on propellant expansion and allows for more advanced, higher density propellants to be used. It will also reduce pressure placed on the barrel in comparison to alternative technologies that offer the same muzzle energy given the fact that it helps spread the propellant's gas much more smoothly during ignition. Currently, there are two principal methods of plasma initiation: the flashboard large area emitter (FLARE) and the triple coaxial plasma igniter (TCPI).

Cloaking Device


cloaking device is a hypothetical or fictional stealth technology that can cause objects, such as spaceships or individuals, to be partially or wholly invisible to parts of the electromagnetic (EM) spectrum. However, over the entire spectrum, a cloaked object scatters more than an uncloaked object. Fictional cloaking devices have been used as plot devices in various media for many years. Developments in scientific research show that real-world cloaking devices can obscure objects from at least one wavelength of EM emissions. Scientists already use artificial materials called metamaterials to bend light around an object.  An operational, non-fictional cloaking device might be an extension of the basic technologies used by stealth aircraft, such as radar-absorbing dark paint, optical camouflage, cooling the outer surface to minimize electromagnetic emissions (usually infrared), or other techniques to minimize other EM emissions, and to minimize particle emissions from the object.

 The use of certain devices to jam and confuse remote sensing devices would greatly aid in this process, but is more properly referred to as "active camouflage". Alternatively, metamaterials provide the theoretical possibility of making electromagnetic radiation pass freely around the 'cloaked' object. Optical metamaterials have featured in several recent proposals for invisibility schemes. "Metamaterials" refers to materials that owe their refractive properties to the way they are structured, rather than the substances that compose them. Using transformation optics it is possible to design the optical parameters of a "cloak" so that it guides light around some region, rendering it invisible over a certain band of wavelengths.

These spatially varying optical parameters do not correspond to any natural material, but may be implemented using metamaterials. There are several theories of cloaking, giving rise to different types of invisibility. In 2014, scientists demonstrated good cloaking performance in murky water, demonstrating that an object shrouded in fog can disappear completely when appropriately coated with metamaterial. This is due to the random scattering of light, such as that which occurs in clouds, fog, milk, frosted glass, etc., combined with the properties of the metamaterial coating. When light is diffused, a thin coat of metamaterial around an object can make it essentially invisible under a range of lighting condition.



Vehicular Communication Systems


Vehicular communication systems are computer networks in which vehicles and roadside units are the communicating nodes, providing each other with information, such as safety warnings and traffic information. They can be effective in avoiding accidents and traffic congestion. Both types of nodes are dedicated short-range communications (DSRC) devices. DSRC works in 5.9 GHz band with bandwidth of 75 MHz and approximate range of 300 m. Vehicular communications is usually developed as a part of intelligent transportation systems (ITS). The main motivation for vehicular communication systems is safety and eliminating the excessive cost of traffic collisions. According to the World Health Organization (WHO), road accidents annually cause approximately 1.2 million deaths worldwide; one fourth of all deaths caused by injury. A study from the American Automobile Association (AAA) concluded that car crashes cost the United States $300 billion per year. It can be used for automated traffic intersection control.

 However the deaths caused by car crashes are in principle avoidable. The U.S. Department of Transportation states that 21,000 of the annual 43,000 road accident deaths in the US are caused by roadway departures and intersection-related incidents. This number can be significantly lowered by deploying local warning systems through vehicular communications. Departing vehicles can inform other vehicles that they intend to depart the highway and arriving cars at intersections can send warning messages to other cars traversing that intersection. Studies show that in Western Europe a mere 5 km/h decrease in average vehicle speeds could result in 25% decrease in deaths.

V2V (short for vehicle to vehicle; see also VANET) is an automobile technology designed to allow automobiles to "talk" to each other. The systems will use a region of the 5.9 GHz band set aside by the United States Congress in 1999, the unlicensed frequency also used by WiFi. V2V is currently in active development by General Motors, which demonstrated the system in 2006 using Cadillac vehicles. Other automakers working on V2V include BMWDaimlerHondaAudiToyotaVolvo and the Car-to-Car communication consortium. V2V is also known as VANETs (vehicular ad hoc networks). It is a variation of MANETs (mobile ad hoc networks), with the emphasis being now the node is the vehicular. In 2001, it was mentioned in a publication that ad hoc networks can be formed by cars and such networks can help overcome blind spots, avoid accidents, etc.

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