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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Stingereffekten : Stingerrobotens inverkan på det sovjetiska arméflygets taktik under Sovjet-Afghanistan kriget

Lindgren, Tobias January 2013 (has links)
Syftet med denna undersökning är att undersöka vilken inverkan Stinger hade på sovjetiska styrkors taktik och nyttjande av arméflygets helikoptrar i Afghanistan. Undersökningen har genomförts som en kvalitativ litteraturstudie. Sovjetiska styrkors och Mujahedins taktiker samt införandet av Stinger har studerats. Två forskningsfrågor har formulerats för att undersöka Sovjets och Mujahedins taktik under kriget; "Hur såg det sovjetiska arméflygets taktik ut vad beträffar nyttjande av helikoptrar innan respektive efter 1986 i Sovjet-Afghanistan kriget". Samt "Hur såg Mujahedins taktik ut innan respektive efter 1986 i Sovjet-Afghanistan kriget." För analys används de grundläggande förmågorna samt taktikanpassning och taktikutveckling som teoretiskt ramverk för att precisera skillnader i de taktiska förändringar som skedde under kriget. Taktiska förändringar i anslutning till införandet av Stinger har diskuterats för att möjligen se om vapnet legat till grund för dessa. Tre slutsatser har dragits av undersökningen: 1) Stinger kan ha krävt att det sovjetiska arméflyget avdelade mer resurser för planering och genomförande av operationer. 2) Stinger reducerade det sovjetiska arméflygets flygningar med helikoptrar under dagtid. 3) Stinger kan ha tvingat sovjetiska helikoptrar att flyga mycket lågt vid flygning i dagsljus.
2

Analysis of Force-Limiting Capabilities of Football Neck Collars

McNeely, David Eugene 02 June 2006 (has links)
The purpose of this study was to examine football neck collars and determine their effectiveness at preventing transient brachial plexopathy and other neck injuries due to football impacts. Transient brachial plexopathy, commonly called a stinger or burner, is an injury to the brachial plexus. As many as 65% of collegiate football players will receive suffer such an injury. Accessory neck collars are worn to mitigate the risk of stingers, although little research has been performed to test their effectiveness. In addition to the standard shoulder pad and helmet combination, three collars were tested: the McDavid Cowboy Collar, a collar designed by a Virginia Tech physician called the Bullock Collar, and a prototype device called the Kerr Collar. This study utilized a Hybrid-III 50th percentile male outfitted with a standard collegiate football helmet and shoulder pads, and impacted with a linear pneumatic impactor. Forty eight total impacts were performed; impacts were performed at side, front, and axial loading impact locations, with low and high speed impacts, and normal and raised shoulder pad configurations. Each collar was effective at some positions, but no collar was effective at all impact locations. The Cowboy Collar reduced lower neck bending moments in the front position, but raised upper neck bending moments. It also reduced lower neck bending moments in the side position, but only in the raised configuration. The Bullock Collar was effective at reducing lower neck bending moment in the side position. The Kerr Collar was effective at reducing lower neck bending moments in the side impact location, and provided a larger percent reduction in impactor force in the axial loading position, compared to the shoulder pads alone. Further testing is needed at lower impact velocities that more closely represent injurious impacts in the field. / Master of Science
3

Impact Biomechanics of the Head and Neck in Football

Rowson, Steven 22 July 2008 (has links)
The research presented in the thesis explores the biomechanics of the head and neck during impacts in football. The research related to the head is geared towards advancing the current understanding of the mechanisms of mild traumatic brain injury, specifically by investigating head accelerations experienced by football players during impacts. To do this, a six degree of freedom sensor that could be integrated into existing football helmets and is capable of measuring linear and angular acceleration about each axis of the head was developed and validated. This sensor was then installed in the helmets of 10 Virginia Tech football players and data was recorded for every game and practice during the 2007 football season. A total 1712 impacts were recorded, creating a large and unbiased dataset. No instrumented player sustained a concussion during the 2007 season. From 2007 head acceleration dataset, 24 of the most severe impacts were modeled using a finite element head model, SIMon (Simulated Injury Monitor). Besides looking at head acceleration, the force transmitted to the mandible by chin straps in football helmets was investigated through impact testing. Little research has been conducted looking at the mandible-chin strap interface in the helmet, and this may be an area of helmet design that can be improved. The research presented in this thesis related to the neck is based on stingers. Football players wear neck collars to prevent stingers; however, their designs are largely based on empirical data, with little biomechanical testing. The load limiting capabilities of various neck collars were investigated through dynamic impact testing with anthropomorphic test devices. It was found that reductions in loads correlate with the degree to which each collar restricted motion of the head and neck. To investigate the differences in results that using different anthropomorphic test devices may present, the matched neck collar tests were performed with the Hybrid III and THOR-NT 50th percentile male dummies. The dummies exhibited the same trends, in that either a load was reduced or increased; however, each load was affected to a different degree. / Master of Science
4

Effects of Shaker Impedance and Transducer Cross-Axis Sensitivity in Frequency Response Function Estimation

Hassan Pour Dargah, Mahmoud 08 October 2012 (has links)
No description available.
5

Möjliga efterträdare till robotsystem 70 / Possible successors to missilesystem 70

Andersson, Martin January 2012 (has links)
Under många år har det funnits en diskussion om att robotsystem 70 behöver bytas ut mot en mer modern korträckviddig eldenhet. Vid luftvärnsregementet har ett konceptförslag framta-gits för en eventuell efterträdare till det nuvarande robotsystemet. För att visa på att det finns fler alternativ som kan vara tänkbara ersättare för robotsystemet har en analys av tre relativt olika eldenheter gjorts utefter vissa värderingskriterier som återspeglas i Försvarsmaktens grundläggande förmågor. Analysen görs genom tre scenarion som skall spegla några av de uppgifter som ett korträckviddigt luftvärn skall hantera. Detta för att visa på fördelar och nackdelar med eldenheterna. Genom scenariostudien framkom sju kriterier som extra viktiga att ta hänsyn till när en ny eldenhet skall inskaffas för att kunna lösa de uppgifter som förvän-tas. Dessa kriterier är: Flermålsförmåga, mörkerkapacitet, verkansområde, skydd av terrängen genom kamouflage, småmålsförmåga, allväderskapacitet och grupperingstid. / For many years, there has been a discussion about the needs to replace missilesystem 70 witha more modern short range air defense unit. The anti-aircraft regiment has prepared a conceptproposal against a possible successor to the current robotsystem. In order to show that thereare other options which can be potential replacements instead of the concept proposal, ananalysis of three quite different launchers is made along certain valuation criteria, which arereflected against the Swedish Armed Forces basic abilities. The analysis is made of three scenariosin order to reflect some of the tasks that a short range air defense has to handle. Thescenarios will also show the advantages and disadvantages of the different units. By the scenariosseven criteria are revealed as extra important to take into account when a new air defenseunit is ordered to be able to solve the expected tasks.These criteria’s are: Multi-Targeting, darkness capacity, performance area, protection of theterrain - camouflage, Small Claims Act, all-weather capability and set up time.
6

Agglomerative clustering for community detection in dynamic graphs

Godbole, Pushkar J. 27 May 2016 (has links)
Agglomerative Clustering techniques work by recursively merging graph vertices into communities, to maximize a clustering quality metric. The metric of Modularity coined by Newman and Girvan, measures the cluster quality based on the premise that, a cluster has collections of vertices more strongly connected internally than would occur from random chance. Various fast and efficient algorithms for community detection based on modularity maximization have been developed for static graphs. However, since many (contemporary) networks are not static but rather evolve over time, the static approaches are rendered inappropriate for clustering of dynamic graphs. Modularity optimization in changing graphs is a relatively new field that entails the need to develop efficient algorithms for detection and maintenance of a community structure while minimizing the “Size of change” and computational effort. The objective of this work was to develop an efficient dynamic agglomerative clustering algorithm that attempts to maximize modularity while minimizing the “size of change” in the transitioning community structure. First we briefly discuss the previous memoryless dynamic reagglomeration approach with localized vertex freeing and illustrate its performance and limitations. Then we describe the new backtracking algorithm followed by its performance results and observations. In experimental analysis of both typical and pathological cases, we evaluate and justify various backtracking and agglomeration strategies in context of the graph structure and incoming stream topologies. Evaluation of the algorithm on social network datasets, including Facebook (SNAP) and PGP Giant Component networks shows significantly improved performance over its conventional static counterpart in terms of execution time, Modularity and Size of Change.
7

Mitigating the MANPADS threat : International Agency, U.S., and Russian efforts /

Bartak, John R. January 2005 (has links) (PDF)
Thesis (M.A. in National Security Affairs)--Naval Postgraduate School, March 2005. / Thesis Advisor(s): Mikhail Tsypkin, Edward J. Laurance. Includes bibliographical references (p. 73-79). Also available online.
8

Luftförsvar för stärkt kustförsvar : En studie om burna Lv-robotsystem i amfibiebataljonen

Holmberg, Andreas January 2018 (has links)
The traditional landings with large warships near the coastline have been replaced by means of vessels moving beyond the horizon from the coast where the landing will take place. The old landing crafts have been replaced by transport helicopters and close air support, a threat that the amphibious battalion lacks resources to meet. The Swedish Armed Forces faces a possible acquisition of MANPADS and therefore the main purpose with this study was to examine the systems: FIM-92 Stinger RMP, Mistral and RBS70 NG, in order to assess which one of them who had the greatest potential to be effective when used by the amphibious battalion in a coastal defense operation. The study was conducted as a multiple criteria decision analysis, based on the concept of military utility. The result indicated that the RBS70 NG was the system that best met the requirements and demonstrated the greatest potential to be military efficient, although Mistral with minor exceptions fulfilled the requirements. As the study was delimited to a theoretical study based on three specific scenarios, further studies are recommended with simulations, as well as field trials before the result can be given a higher validity. The result, however, already helps us to understand how MANPADS contributes with military utility in coastal defense operations. / De traditionella landstigningarna med stora fartyg uppträdandes kustnära har ersatts med metoder innebärandes att fartygen rör sig bortom horisonten från den kust där landsättningen/landstigningen ska ske. De gamla landstigningsbåtarna har i hög grad ersatts med helikoptrar som understödda av attackhelikoptrar och flygplan utgör den nya dimensionerande hotbilden. En hotbild som amfibiebataljonen saknar resurser för att möta. Då Försvarsmakten står inför en eventuell anskaffning av ett buret luftvärnssystem till amfibiebataljonen har denna undersöknings främsta syfte varit att bedöma vilket av systemen FIM-92 Stinger RMP, Mistral eller RBS70 NG som uppvisat störst potential att vara militärt effektivt när de nyttjas av en amfibiebataljon i kustförsvarsoperationer. Undersökningen genomfördes som en komparativ analys med multimålmetod och tre olika typfall som grund. Jämförelsen tog sin utgångspunkt kring teoribildningen om militär nytta och då mer specifikt militär effektivitet. Resultatet indikerade att RBS70 NG var det system som bäst mötte amfibiebataljonens krav och därmed uppvisade störst potential att vara militärt effektivt, även om Mistral med enstaka undantag också uppfyllde kraven till synes utan begränsningar. Då studien avgränsats till en teoretisk jämförelse i tre specifika typfall, rekommenderas fortsatta studier med såväl simuleringar som praktiska prov innan resultatet kan ges en högre validitet. Resultatet bidrar däremot redan nu till en förståelse för vad som ökar den militära effektivitetenvid genomförande av kustförsvarsoperationer.
9

Mitigating the MANPADS threat: international agency, U.S., and Russian efforts / Mitigating the Manned Portable Air Defense Systems threat

Bartak, John R. 03 1900 (has links)
Approved for public release, distribution is unlimited / There are in excess of 500,000 Manned Portable Air Defense Systems (MANPADS) in worldwide inventories including several thousand outside of government control. MANPADS are surface-to-air missile systems enabling the operator to launch missiles at aircraft from the ground. The most common MANPADS are the Russian SA-7 and U.S. Stinger, which feature infrared guidance systems. The concern that MANPADS can easily be acquired by non-state actors' intent on downing civilian and military aircraft has led international agencies, the U.S., and Russia to implement measures to reduce the risk of a MANPADS attack. International agencies such as the Wassenaar Arrangement work to stop illegal MANPADS proliferation. The U.S. MANPADS Defense Act and the U.S. Department of Homeland Security have implemented measures to counter the MANPADS threat. Russia has revised its export controls and forged a counter-proliferation agreement with most CIS countries. However, the multilateral initiatives to better control MANPADS stocks and transfers are far from comprehensive. A new approach to mitigating the MANPADS threat adopts elements from the 1997 Mine Ban Treaty and the Landmine Monitor. The conclusion of this thesis is that if MANPADS counter-proliferation efforts remain status quo an attack on a commercial aircraft in the western world is imminent.
10

Výroba součásti technologií přesného stříhání / Fineblanking component and its manufacturing

Lata, Miroslav January 2010 (has links)
The diploma thesis deals with a propose of a new manufacturing technology of component called „KULISA“ drawing number 4-DP-05-10/01. The beginning of this work is prepared as a literary study about blanking. There are explained some basic concepts necessary to introduce a blanking topic. Other interest of this work is an assessment of actual state of conventional blanking technology which is being currently used for component production. With regard to the deficiencies of the existing method is proposed new technology of fine blanking. In the proposal is evaluated technological site of component construction and blanking tools are proposed with stress analysis included. Last part of the work deals with the economic evaluation, where is being compared efficiency of existing and new technology.

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