Relative File Organization
This topic discusses different types of indexing techniques that allows the location of records in a file relatively fast with fewer accesses. The techniques that will be addressed deals with random access file organization only. As this is the best file organization that allows records to be stored randomly rather than sequentially or in a contiguous manner. By using direct addressing, a predictable relationship between a key of a record and the location of that record on an external file is established.
Two different forms of addressing can be used to establish this relationship:
1.Absolute Addressing
2.Relative Addressing
Absolute addressing make use of the storage devices to determine the relationship, and therefore it is machine dependent, e.g., cylinder-number, surface-number, and record-number if we are using cylinder addressing or sector-number and record-number if sector addressing is being used.
Hashing
Hashing is the application of a function to the key value of a record that results in mapping the range of possible key values into a smaller range of relative addresses. For example, if a company is to maintain data of 10,000 employees by using the employee’s social security number, which ranges from 1 to 999999999, into 10,000 relative positions. The hash function to be applied to the social security number must be able to match each 10,000 social security number into each relative address available. However, collisions do occur. Collisions occurs when two different keys, in this case two social security numbers, hash into the same relative address. These two different keys are
termed synonyms.
The relationship between the file space and the number of keys is described as the load factor. Load factor is the ratio of the number of key values to be stored versus the number of file positions:
Load Factor = number of key values / number of file positions
Prime-Number Division Remainder
Prime number division remainder method works just like using the mod operator in Pascal or the % operator in C or C++. The key to a record is divided with a prime-number and the remainder from the division is used as the relative address for that record.
Digit Extraction
This method analyzes the key values to determine which digit positions in the key are more evenly distributed. The more evenly distributed digit positions are assigned from right to left, and the digit values are extracted and used as the relative address. For example, for a key value 546032178, the relative address could be 8134, from left to right the first, third, fifth, and eighth digit positions has been extracted.
The sinking of the Lusitania was a tragic event. It occurred on May 7th, 1915 in the North Atlantic ocean. The famous British ocean liner had departed from New York City and was off the coast of Ireland when a German submarine fired torpedoes. The ship had roughly 1,900 passengers on board, most of which were American citizens. The ship was meant for passengers and not for cargo but as lots of reporters have stated there was in fact a handful of war materials aboard the ship which was kept secret from its passengers.Prior to the sinking the Germans had declared that the waters around the British Isles were considered to be a war zone.1 This war zone idea was backed by the fact that the Germans admitted to enforce unrestricted submarine warfare; meaning if you were in the water you were getting blown up with or without prior knowledge. It took a total of eighteen minutes for the Lusitania, in its entirety, to disappear beneath the waves of the North Atlantic ocean.2 After the ship had sunk the American press had openly and with lots of determination and passion deemed the event uncivilized. However, the Lusitania was not the only ship that was torpedoed. A year later in 1916 the Sussex, an unarmed French passenger ship was sunk by another German submarine. 3
All over the world there are millions of people use credit card and on-line shopping. Every individual gets different numbers for credit card and for transcription of on-line-shopping. Where did all this number come from? Are the numbers in order? No, those numbers are made by RSA algorithm.
...e went into motion. Possible projectiles of the trebuchet were living prisoners, jugs of Greek fire, rocks, and animals. Another large weapon of siege was used primarily in storms, the battering ram. In its early stages, the ram was no more than a hefty beam with a mass of metal attached to the end. Men would hoist the cumbersome boom onto their shoulders and run into a wall or door as many times as needed until the surface under attack gave way. In the Middle Ages, it was developed into more of a machine, for the ram hung from the center of a tent under which the men operating the ram could hide. The ram could be swung like a pendulum much more easily than having to constantly run back and forth. Also, castle guards often poured hot oil or other things onto the ram and its engineers. The tent, which was on wheels, protected the men and the battering ram as well.
In 1915 the cruise liner lusitania was sunk by a german U boat just south of the coast of ireland. There were 2 explosions on the hull of the lusitania then it sunk in 18 minutes and 128 american lives were lost, this rightfully angered the american public but they were being lied to (data set 8). Britain used these civilian passengers as meat shields for the ammunition they were carrying on the ship. according to the british reports the lusitania was hit by 2 torpedoes, but according to the germans they only fired 1 torpedo, the second explosion was actually the onboard ammunition exploding, but the british straight lied to everybody and called it a second torpedo (outside source). According to most people this event is why the US joined the war but that is
The Lusitania was a British ship that had 128 Americans. Lusitania was a 30,395 - ton four-funnel 788 – foot ship. Captain William Turner, steadfast and trustworthy but over can find believed that “a torpedo can’t get the Lusitania she runs too fast.” The captain of the Lusitania was Capt. W.H. Turner his rasp were humorous and not a way compatible with one another. He was danged with the supervision of the comply operas of the vessel and of its larges crew. It was his duty to bring his craft safely to harbor. May 1, 1915 the Lusitania set sail from New York. A luxury liner the Lusitania had sailed across the Atlantic without incident during the first mouths of the war .When the Lusitania sank it sank in just 18 minutes killing 1,118 people.
Larson talks in detail about both ship's journey and how they meet up. In the book, there were many signs that foreshadowed the demise of the Lusitania. One example, is the newspaper article that warns all ships passing through the war zone will be sunk. An article in a newspaper ad warns people to not go in the war zone. The ad was not taken seriously and a passenger later said that many people did not take any notice of it because it was such a daring idea ("How the Sinking"). If this warning was put in papers, how could this not be seen as an accident when Germany is basically telling people to not enter this spot. Nobody can prove that U-20 was on a hunt for the Lusitania, but there were many warnings given to the Lusitania by Germans. On the Lusitania, there was a room built to seek U-boats to keep the ship from getting sunk. In the book, it talks about the room, Room 40. It was said to know that a U-boat was heading the same direction they are going. They also knew that the boat was supposed to sink any ship they could (Larson 169). The Lusitania knew that a U-boat was heading directly towards them and yet did not change their course. Captain Turner must have been sure his ship could beat out a U-boat and nobody would dare to sink him. In the book, many points are made in why the Lusitania should sail the sea's
Slaves are not inherently dangerous until they have come to understand and acknowledge the evils of slavery. It is only when they are educated and made aware of the situation that they were forced into, that they loathe the concept of being enslaved. Further, this enlightenment threatens the entire foundation of slavery as the enslaved have the mental capability to rebel against their master, although a majorit...
As printed on a notice, “...any vessels flying the flag of Great Britain, or any of her allies, are liable to destruction in those waters (adjacent to the British Isles) and that travellers sailing in the war zone on ships of Great Britain or her allies do so at their own risk.” Despite these dire warnings 1,962 people still got on the Lusitania, a British passenger ship, on her 202nd voyage through the war torn waters of Great Britain.
There is definitely going to be dynamic change in people’s lives in the future as virtual reality has a lot to offer. With advancement in vr app development we should expect the world to be able to share knowledge and information that would affect our lives. Using virtual reality, people would be able to receive education in remote areas and also share updated information and knowledge across different parts of the world. Students will be able to concentrate better as they would not have any distractions while learning from the virtual reality training
Many worry about the uses it will be put; fearing the human race will evolve into insouciant libertines gorged on a diet of ersatz sex! For those who dread what the future will bring to a human race given reign to experience its personal "fantasy realities", it's worth noting that the stereoscopic viewer - the nearest anyone could get to a virtual reality system at the time - fell into ill-repute in Victorian times due to the proliferation of pornographic material. It seems the engineering progress which has accompanied the presentation of virtual reality has not been matched by a commensurate progress in the fantasies which people hope to have sated by that technology! It is with some sadness that Gates (1995) predicts that concupiscence will almost certainly be the driving factor in low-cost virtual reality systems. So is the future for VR predominantly as a vehicle for entertainment? Is it going to be good for anyone but salacious epicures? Certainly the key concept of immersion does perhaps suggest its predominant applications exist more in the world of our fantasies than in the world of our duties. However there are a raft of applications where VR and multimedia concepts and technologies are beginning to contribute to our abilities to execute our jobs, perform new jobs or do old jobs differently. Not strictly pure VR or multimedia, three important categories are
[7] Elmasri & Navathe. Fundamentals of database systems, 4th edition. Addison-Wesley, Redwood City, CA. 2004.
While most siege weapons shared the same objective, throwing a massive projectile at someone or something, they came in various shapes and sizes, with different types of material being tossed. Counterweight trebuchets, onagers and mangonels, and ballista are some of the most common ones used during the medieval period. Most of these projectile siege weapons were made of wood, with many gears and ropes providing the way to transfer momentum with the help of a lever from the counterweights to the projectile. For the counterweight trebuchet, this was exactly the way to go. While the trebuchet was a siege engine good for long distance, it had unfortunate characteristics of being big and therefore hard to move. This was not such a problem for the onager, which was a smaller catapult used in the post roman period. The onager used torsional pressures from twisted rope to fire projectiles from a sling, (McDonald, 2010). The mangonel was a less powerful design that used a fixed bowl to fire its projectiles and had a lower angle of travel for its
Fang Cheng Leu, Yin-Te Tsai, Chuan Yi Tang [2000] have proposed an effective external sorting algorithm. This algorithm utilization Divide and Conquer procedure. This paper exhibits an ideal external sorting algorithm for two-level memory model. This system is not the same as the universal external merge sort and it utilizes the examining data to decrease the circle I/os in the outside stage. The algorithm is proficient, straightforward and it makes a great utilization of memory accessible in the late nature's turf. Under the certain memory demand, this algorithm runs with ideal number of disk I/os and each one record is precisely perused twice and composed twice.
This white paper identifies some of the considerations and techniques which can significantly improve the performance of the systems handling large amounts of data.
When planning to implement a document management system, there are many factors to consider. First you have to consider how you want to store your documents, be it electronic, paper format, or both; you have to have adequate storage space. Next you have to decide whether you are going to attempt to archive old documents your organization has in storage. A major factor in determining the format you are going to save your documents in is to decide the length of time you wish to keep you documents and the amount of space you have in which to keep your documents. If you are going to keep your documents in a paper format you have to keep in mind the amount of space it will take to store them. Another consideration when determining storage of your organizations documents is how you want to organize your documents be it chronologically or subject based, you need to decide what works best for your organization. And lastly you have to decide how you are going to take those old documents, created before computers, and turn them in to a format which can be stored electronically. There are many different formats which can be beneficial when keeping an archive of documents. There are many reasons why documents need to be managed. First and foremost they serve as a historical log of where your organization came from and they will help shape where your organization can go in the future. Documents can be a reference of how past projects were worked and offer practical solutions for issues which come up in all projects. Keeping documents can be beneficial for every organization, from keeping records to showing where the organization can go, documents play a part in the every day workings of every organization.