Global Positioning System Essays (929 words) -

Global Positioning System What is GPS? The global positioning system is a satellite-based navigation system, developed and operated by the U.S. Department of Defence, consisting of a network of 24 orbiting satellites that are eleven thousand nautical miles in space, at an inclination of 55 degrees and in six different orbital paths. The satellites are constantly moving, making two complete orbits around the Earth in just less than 24 hours. The GPS satellites are referred to as NAVSTAR satellites. GPS uses these 'man-made' stars as reference points to calculate positions accurate to a matter of metres. Advanced forms of GPS can make measurements to better than a centimetre. GPS now permits land, sea and airborne users to determine their three dimensional position anywhere in the world very precisely and accurately. The user segment consists of receivers, processors and antennas. The vast majority of applications of precision possible with GPS is primarily of scientific and military use, but it is worth noting that these days, GPS is finding its way into cars, boats, planes, construction equipment and a lot more. Principles of Operation of GPS The GPS satellites orbit the Earth twice a day, 11,000 miles above the Earth transmitting their precise position and elevation. In brief, the GPS receiver acquires the signal, then measures the interval between transmission and receipt of the signal to determine the distance between the receiver and the satellite. Once the receiver has calculated this data for at least three satellites, its location on the Earth's surface can be determined. This is the basis of triangulation, which works as follows: -Determining the exact distance to one satellite narrows down the receiver's position to some place on an imaginary sphere. -Knowing the exact distance to a second satellite narrows the position down to the intersection of two spheres or a circle of points. -Knowing the exact position of a third satellite narrows the possibilities down to two points of intersection. The exact position is usually known now because one of the points is usually not on the surface of the Earth. A fourth satellite position can be used to find the one single location without any doubt. (This will be discussed later). This is how position is calculated, but how is the distance measured from the receiver to the satellite? Basically, it is measured by timing how long it takes for a signal sent from the satellite to arrive at the receiver. Both the satellite and the receiver simultaneously generate the same pseudo random code. The time delay before both codes will synchronise, multiplied by the speed of light gives the distance. Diagrammatically, It should be explained that the pseudo random code is just a very complicated code that looks like random electrical noise. The reasons for the complexity are: -It helps make sure that the receiver doesn't accidentally sync up to some other signal. -It guarantees that the receiver doesn't accidentally pick up another satellite's signal as each satellite has its own unique pseudo random code. -The code makes it possible to use'information theory' to 'amplify' the GPS signal. As well as the GPS signal containing a pseudo random code, every satellite also transmits almanac and ephemeris data. The almanac data is general information on the location and the health of each satellite in the constellation, which can be received from any satellite. Ephemeris data is the precise satellite positioning information that is used by the GPS receiver to compute its position. Each satellite transmits its own ephemeris data. It is of utmost importance that timing is extremely precise. Satellites have atomic clocks that can make precise time measurements, while available GPS receivers don't. To correct this, a fourth satellite distance measurement is made, providing perfect timing or atomic accuracy clock measurements. One consequence of this principle is that any decent GPS receiver will need to have at least four channels so that it can make the four measurements simultaneously. Exact distance has now been obtained and the exact position of the satellite is known due to ephemeris data. Therefore, perfect position calculations could be made. It is worth mentioning that the Department of Defence constantly monitors the GPS satellites. There is a master control station in Colorado Springs and five monitor stations and three ground antennas located throughout the world. The monitor stations send the information they collect from each of the satellites back to the master control station, which computes extremely precise satellite orbits. The information is then formatted into updated navigation messages for each satellite. The updated information is transmitted to each satellite via ground

Biological Weapons - Description and Potential List

Biological Weapons - Description and Potential List Biological Weapons Biological weapons are toxic materials produced from pathogenic organisms (usually microbes) or artificially manufactured toxic substances that are used to intentionally interfere with the biological processes of a host. These substances work to kill or incapacitate the host. Biological weapons may be used to target living organisms including humans, animals, or vegetation. They may also be used to contaminate nonliving substances such as air, water and soil. Microscopic Weapons There are a variety of microorganisms that can be used as biological weapons. Agents are commonly chosen because they are highly toxic, easily obtainable and inexpensive to produce, easily transferable from person to person, can be dispersed in aerosol form, or have no known vaccine. Common microbes used as biological weapons include: Bacteria -  these prokaryotic organisms  are capable of infecting cells and causing disease. Bacteria cause diseases such as anthrax and botulism. Viruses - are  about 1,000 times smaller than bacteria and require a host to replicate. They are responsible for disease including smallpox,  flesh-eating disease, Ebloa disease, and Zika disease. Fungi - some of these  eukaryotic organisms  contain deadly toxins that are harmful to plants, animals, and humans. They cause diseases such as  rice blast, wheat  stem rust,  aspergillosis (caused by inhaling fungal  spores), and bovine foot rot. Toxins - poisonous substances that can be extracted from plants, animals, bacteria, and fungi. Toxic substances that can be used as biological weapons include ricin and venom from animals such as snakes and spiders. Distribution Methods While it is possible to develop biological weapons from microbes,  finding a means of distributing the substances is difficult. One possible way is through aerosols. This can be ineffective as the materials often get clogged when spraying. Biological agents distributed by air may also be destroyed by UV light or rain may wash them away. Another method of distribution may be to attach the toxins to a bomb so that they may be released upon explosion. The problem with this is that the microbes will most likely be destroyed by the explosion as well. Toxins could be used to contaminate food and water supplies. This method would require extremely large amounts of toxin for a large scale attack. Protective Measures A number of measures can be taken to protect individuals against biological attacks. Should an aerosol attack occur, removing your clothing and showering are good methods for removing toxins. Biological weapons dont typically adhere to clothing or skin, but can be dangerous should they enter cuts or lesions on the skin. Protective clothing, such as masks and gloves, can provide protection against airborne particles. Other types of protective measures include administering  antibiotics and vaccines. Potential Biological Weapons Below is a list of a few biological organisms that may potentially be used as biological weapons. Microbe Natural Environment Target Host Mode of Contraction Diseases/Symptoms Anthrax Bacillus anthracis Soil Humans, Domestic Animals Open Wounds, Inhalation Pulmonary Anthrax Septicemia, Flu-like symptoms Clostridium botulinum Soil Humans Contaminated Food or Water, Inhalation Clostridium perfringens Intestines of humans and other animals, Soil Humans, Domestic Animals Open Wounds Gas gangrene, Severe Abdominal Cramps, Diarrhea RICIN Protein Toxin Extracted from Castor Bean Plants Humans Contaminated Food or Water, Inhalation, Injection Severe Abdominal Pain, Watery and Bloody Diarrhea, Vomiting, Weakness, Fever, Cough, and Pulmonary Edema Smallpox Eradicated from Nature, Now Obtained from Laboratory Stockpiles Humans Direct Contact with Bodily Fluids or Contaminated Objects, Inhalation Persistent Fever, Vomiting, Rash on Tongue and in Mouth, Rash and Bumps on Skin

Is film dead should it be buried in favor of digital film Essay

Is film dead should it be buried in favor of digital film - Essay Example For nearly a century, film has been the leading choice of professionals for capturing images, unraveling a multibillion-dollar industry until 2000. Digital capturing devices got their start in 1969 at Bells Lab with the invention of the charge-coupled device (CCD). The CCD, an invention by George Smith and Willard Boyle, uses an electrical charge to activate pixels when light hit the censors rather than create an image through grain re-arrangement It was not until the Dogme 95 era in the early 1990's that filmmakers saw the potential of digital cinema as a viable form for telling stories. Approximately a decade later, George Lucas and Sony teamed up to create the first professional digital video cameras that offer many of the same features of 35mm motion picture cameras. The release of Star Wars II in 2002 marks the instance in the film history when a one-hundred percent digital production of the film becomes successful, sparking the embracement of digital film revolution. For nearly a decade after 2002, companies such as ARRI, Red, Sony, Canon, and Panavision on digital film have spent billions of dollars on research and development to further the efficiency of digital film cameras. It is a digital millennium. Everything is going digital: cars, houses, computers, everything under the sun is. Just like in every other industry, controversy dominates as to which between the devil we know (old), and the strange angel (new), is the path to maximum achievement and not doom of the film industry. This study will discuss in depth the features of digital film that saw it overtake and kill the film, plus the mileage it has so far gained above it. Color grading This is the process of alteration and enhancement of an image, video, or motion picture to achieve a certain appearance. Digital film allows for capturing and post-editing, making this process much easier as compared to film. According to Paramour Productions, digital shooting allows for post-shoot editing of indiv idual scenes unlike in the film era that supported only two shooting modes: tungsten-balanced and daylight-balanced films. This means color temp fluctuation was very likely, varying as per the available light’s intensity, which meant all the footage needed correction to achieve a white consistent point to start the grading. This further explains why in the film era, a shoot required several rooms with different customizations to achieve variations. However, today, digital filming allows shooting from a single location or prop and with the use of advanced software, allows easy color alteration or grading from just a computer unlike the use of actual rooms, props or scenes to achieve certain effects. In addition, and according to Hoad, Hollywood incorporates much use of digital color grading to achieve extreme special effects impossible with film as it allows for post-production alteration as with the 2000 movie O Brother, Where Art Thou? It is the first filming to be put on a hard drive, allowing for creation of a Digital Intermediate point (DI), from where the editor used â€Å"virtual crayons† to achieve an explosion of special effects. The guardian refers to color grading as an absolute necessity. Distribution, marketing, and exhibition According to Fischer (95), in the year 2000, Hollywood disseminated a full movie, Titan AE via the internet, which it digitized before sending it to its destination,