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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

The Royal Navy and Soviet seapower, 1930-1950 : intelligence, naval cooperation and antagonism

Ryan, Joseph Francis January 1996 (has links)
British estimates of Soviet seapower from 1930 to 1950 covered three main phases. These were primarily characterised by pre-war suspicion of Communism and the Soviet Union, enforced wartime naval cooperation from June 1941 until the end of the Second World War and, finally, a shift towards Cold War antagonism.It is argued that the Admiralty's Naval Intelligence Division was able to collect sufficient data to maintain a credible intelligence picture of the Soviet Navy's order of battle and war-fighting capabilities, thereby allowing informed decision-making in London. In general, the United Kingdom considered that the Red Navy was poorly equipped and trained, and that it posed little threat to British interests. This was borne out by the Soviet Union's poor employment of seapower during the war.Knowledge of the Soviet Navy was always difficult to obtain. However, a major finding of this thesis is that the wartime Anglo-Soviet alliance allowed British naval representativesin the USSR unprecedented access to Russian warships, facilities and commanders. Though the basing of a naval mission in Russia was principally intended to assist in the common fight against Nazi Germany and to promote liaison between the Royal and Soviet Navies, especially with regard to the Arctic convoys, the British also took the opportunity to examine the maritime forces of their long-standing Communist rival at close quarters. It is contended, therefore, that improved intelligence on the Soviet Navy was made possible by wartime naval collaboration. To examine this assertion, relevant naval aspects of the Great Patriotic War of 1941-1945 are covered in detail in the thesis.After 1945, the Red fleets required some time for consolidation before expansion was possible. The Soviet Navy remained an intelligence target, but British wartime assessments largely held good to the end of the decade.
2

British casualties on the Western Front 1914-1918 and their influence on the military conduct of the Second World War

Whittle, Eric Yvon January 1991 (has links)
It is often asserted that British army casualties in the Great War were carelessly incurred and that this influenced the way Britain fought in the Second World War. Manpower was a prime resource in the mobilisation for total war but its scarcity only fully realised by end of 1917 when the army was cautioned about casualties. The government, however, had feared an early popular reaction against mounting casualties. It did not materialise: the incidence of casualties was diffused over time, and households had no mass media spreading intimate awareness of battlefield conditions. The army itself never mutinied over casualties or refused to fight. The country considered the casualties grievous but not inordinate or unnecessary. Between the wars unemployment and 'consumerism' mattered more to people than memories of the Great War., kept ritually alive by annual Armistice Day services. Welfare benefits increased, more children went to secondary school but social and political change was tardy. Many intellectuals turned pacifist but Nazi Germany made an anti-war-stance difficult. Air raids rather than memories of Great War casualties preoccupied the nation as it armed for war. In the Second World War army casualty lists were not regularly lengthy until the beginning of 1944 and did not have an adverse impact on civilian morale. The manpower shortage became acute earlier, in 1942, and army commanders were alerted to replacement problems. Politically, Churchill desired a strong, victorious British army but lack of men induced caution about casualties, particularly in relation to the invasion of Normandy, involving frontal amphibious attack on the German army. This caution communicated itself to the citizen armies in the field, which showed little natural bent for soldiering. These circumstances governed the way the army fought in the Second World War, not memories of Great War casualties - which were more numerous because of the extent over time and scale of the fighting.
3

Getting it there : the relationship between military logistics and strategic effectiveness

Kane, Thomas M. January 1998 (has links)
Although experienced military commanders have always emphasised the importance of logistics in warfare, scholarly researchers have failed to explain how supply factors affect strategic performance. Martin van Creveld, the leading academic author on this subject, argues that detailed logistical planning has little value in war. This thesis counters Van Creveld's argument with the suggestion that logistical planning is indeed decisive in warfare, not only because of the tangible importance of supplies but because of their intangible importance as well. The author portrays logistics as an "arbiter of opportunity" which helps to determine the range of strategic options which military commanders will have at their disposal. This thesis goes on to demonstrate the truth of this statement through the structured, focused comparison of five historical case studies. In conclusion, the author discusses the implications of his work, not only for logistical studies, but for the study of international relations in general.
4

Identification of driving manoeuvres using smartphone-based GPS and inertial forces measurement

Engelbrecht, Jarrett 03 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Road accidents are a growing concern for governments and is rising to become one of the leading causes of death in developing countries. Aggressive driving is one of the major causes of road accidents, and it is therefore important to investigate ways to improve people's driving habits. The ubiquitous presence of smartphones provides a new platform on which to implement sensor networks in vehicles, and therefore this thesis focuses on the use of smartphones to monitor a person's driving behaviour. The framework for a smartphone-based system that can detect and classify various driving manoeuvres is researched. As a proof of concept, a system is developed that specifically detects lateral driving manoeuvres and that classifies them as aggressive or not, using a supervised learning classification algorithm. Existing solutions found in research literature are investigated and presented. The best existing solution, a dynamic time warping classification approach, is also implemented and tested. We use an aggressive driving model that is based on the angle of a turn, the lateral force exerted on the vehicle and its speed through the turn. The tests and results of the implemented manoeuvre detection and classifcation algorithms are presented, and thoroughly discussed. The performance of each classifer is tested using the same data set, and a quantitative comparison are made between them. Ultimately, a lateral driving manoeuvre detection and recognition system was successfully developed, and its potential to be implemented on a smartphone was substantiated. The suitability of supervised learning classi ers for classifying aggressive driving, in comparison to dynamic time warping classifcation, was successfully demonstrated and used to validate our aggressive driving model. Conceivably, this work can be employed in the future to develop an holistic smartphone-based driver behaviour monitoring system, which can be easily deployed on a large scale to help make the public drive better. This would make our roads safer, reducing the occurrence of road accidents and fatalities. / AFRIKAANSE OPSOMMING: Padongelukkige is 'n groeiende bekommernis vir regerings en is een van die hoof oorsake van sterftes in ontwikkelende lande. Aggressiewe bestuur is een van die grootste oorsake van padongelukke, en dit is dus belangrik om ondersoek in te stel oor hoe mense se bestuurgewoontes verbeter kan word. Die alomteenwoordigheid van slimfone bied 'n nuwe platform waarop sensor netwerke geïmplementeer kan word in voertuie. Daarom fokus hierdie tesis op die gebruik van slimfone om 'n persoon se bestuurgedrag te moniteer. Die raamwerk vir 'n slimfoon-gebaseerde stelsel wat verskeie bestuurbewegings kan opspoor en klassifiseer is nagevors. As 'n bewys van die konsep, is 'n stelsel ontwikkel wat spesifiek laterale bestuurbewegings opspoor en dan klassifiseer of dit aggressief is of nie, met behulp van 'n klassifikasie algoritme wat onder toesig geleer is. Bestaande oplossings gevind in navorsingsliteratuur word ondersoek en aangebied. Die beste bestaande oplossing, 'n dinamiese tyd buiging klassifikasie benadering, word ook geïmplementeer en getoets. Ons gebruik 'n aggressiewe bestuurmodel wat gebaseer is op die hoek van 'n draai, die laterale krag wat uitgeofen is op die voertuig en sy spoed deur die draai. Die toetse en die resultate van die geïmplementeer beweging opsporing en klassifisering algoritmes word aangebied, en deeglik bespreek. Die prestasie van elke klassifiseerder is getoets met behulp van dieselfde stel data, en 'n kwantitatiewe vergelyking is tussen beide gemaak. Oplaas is 'n laterale bestuurbeweging bemerking en herkenning stelsel suksesvol ontwikkel en sy potensiaal om geïmplementeer te word op 'n slimfoon is gestaaf. Die geskiktheid van die onder-toesig-geleerde klassifiseerders vir die klassifikasie van aggressiewe bestuur, in vergelyking met dinamiese tyd buiging klassifikasie, was suksesvol gedemonstreer en gebruik om ons aggressiewe bestuurmodel te bewys. Hierdie werk kan in die toekoms gebruik word in 'n holistiese slimfoon-gebaseerde bestuurdergedrag monitering stelsel, wat maklik op groot skaal ontplooi kan word om te help verseker dat die publiek beter bestuur. Dit sal ons paaie veiliger maak, en die voorkoms van padongelukke en sterftes verminder.
5

Transient tyre modelling for the simulation of drivetrain dynamic response under low-to-zero speed traction manoeuvres

Bartram, Matthew January 2011 (has links)
The work presented in this thesis is dedicated to the study of transient tyre dynamics and how these influence the dynamic behaviour of the vehicle and its driveline, with the main focus being on low-to-zero speed manoeuvres such as pull-away events. The bulk of the work focuses on the amalgamation of the hitherto disparate fields of driveline modelling and detailed tyre modelling. Several tyre models are employed and their relative advantages and disadvantages analysed. The observed dynamic behaviour is correlated to the inherent structure of each tyre model in order for the most appropriate for driveline studies to be identified. The main simulation studies are split into two parts: the first comprises a study into isolated driveline dynamics; where the yaw, pitch and roll behaviours of the vehicle body are neglected. A relatively detailed driveline model with an open differential is used with tyre models of increasing complexity with the aim of determining when increased model detail fails to increase the accuracy of the results. The second part is concerned with the study of how the dynamics of the vehicle body and suspension affect tyre model performance and associated effects on the driveline behaviour. For this, the driveline and tyre models are incorporated into a full six degree-of-freedom vehicle model with full suspension effects. Frequency migration on low-μ surfaces is successfully explained via the decoupling of the vehicle and driveline inertias. Frequencies observed in FFT analyses of the simulation results correspond to those obtained through eigen-analysis of appropriately modified state-space models with varying degrees of coupling that reflect the vehicle travelling on uniform low- or split-μ surfaces. The main finding of the thesis is that this decoupling theory can also be applied to high-speed take-off manoeuvres, as it is the position along the tyre slip-force curve that dictates decoupling; i.e. if the curve has saturated. This leads to the effective traction stiffness being zero, which modifies the equations of motion and subsequently the system eigenvalues. A series of measurements are taken in order to verify the findings from the simulation work. Manoeuvres analogous to those simulated are carried out. It is found that only the simulation of split-μ conditions is necessary, as the results from the low-μ test show a similar pattern to those seen on the split-μ surface.
6

Application of military logistic techniques to industrial applications.

Singh, Navin Runjit. January 2002 (has links)
The main reason for the low production efficiencies at North Coast Milling is the frequent stoppages due to equipment breakdowns and the requirement for unscheduled maintenance. In order for this factory to be able to reach the desired efficiencies, it is imperative that downtime and cost drivers in the production lines be identified and rectified. In order to achieve world-class performance, more and more companies are replacing their reactive strategies for maintenance with proactive strategies like Preventive maintenance (PM), Reliability-centred maintenance (RCM) and Condition based maintenance (CBM) and aggressive strategies like Total Productive Maintenance (TPM). While these newer maintenance strategies require increased commitments to training, resources and integration, they also promise to improve performance. New asset management philosophies are being implemented world-wide in an effort to improve industrial system reliability as well as to reduce maintenance costs. Concepts such as TPM, RCM and CBM are being customised for implementation in various industries. Real-time condition monitoring via computerised maintenance management systems has helped make it possible to transfer from a time-based maintenance strategy to a condition-based maintenance strategy. Detecting possible future failures is now a cost-effective reality that reduces considerably the risk of catastrophic failures and system breakdowns. The aIm of the study is to apply military logistic techniques to the industrial environment of North Coast Milling in order to identify downtime and cost drivers. It will be shown that more of the military logistics techniques can be incorporated into some of the existing maintenance techniques at this factory, which would aid in the achievement of maximum plant utilisation and minimum downtime.! / Thesis (MBA)- University of Natal, 2002.
7

Prédiction de la distance résiduelle d'un véhicule électrique

Dubé, Renaud January 2014 (has links)
Dans l’optique de limiter l’impact environnemental négatif de l’utilisation immodérée du pétrole, le développement de nouveaux moyens de transport plus écoénergétiques est favorisé. Bien qu’elle offr actuellement une autonomie considérablement plus limitée que celle du véhicule à gazoline, la technologie du véhicule électrique est la plus prisée. Liée à la faible autonomie des véhicules électriques, l’angoisse de la panne, un sentiment éprouvé chez les utilisateurs de ce type de véhicules qui a été identifié lors des années 1990, représente actuellement une barrière socio-technologique importante au développement de la technologie du véhicule électrique. Afin de limiter les risques de panne d'énergie et dans le but de renforcer la confiance du conducteur face à cette nouvelle technologie de véhicule, une méthode précise de prédiction de la distance résiduelle est proposée. Cette méthode originale utilise un algorithme de prédiction du trajet basé sur l'identification des virages à gauche et à droite. Sachant que le type de trajet parcouru influence de façon importante la distance résiduelle, cette stratégie de prédiction offr une amélioration de la précision face aux autres couramment utilisées. La pertinence de cette nouvelle méthode de prédiction sera démontrée à la fois en situation de simulation et d’expérimentation.
8

Tyre models for vehicle handling analysis under steady-state and transient manoeuvres

Mavros, Georgios January 2005 (has links)
The work presented in this thesis is devoted to the study of mechanism of tyre force generation and its influence on handling dynamics of ground vehicles. The main part of the work involves the development of tyre models for use under steady-state and transient operating conditions. The general capability of these models is assessedin a full vehicle simulation environment. The interaction between tyre and vehicle dynamics is critically evaluated and the observed vehicle behaviour is related to the inherent characteristics of different tyre models. In the field of steady-state tyre modelling, two versions of a numerical tyre model are developed. The modelling procedure is carried out in accordance with the viscoelastic properties of rubber, which influence the mechanical properties of the tyre structure and play a significant role in the determination of friction in the tyre contact patch. Whilst the initial simple version of the tyre model assumes a parabolic pressure distribution along the contact, a later more elaborate model employs a numerical method for the calculation of the actual normal pressure distribution. The changes in the pressure distribution as a result of variations in the rolling velocity and normal load influence mainly the levels of self-aligning moment, whilst the force characteristics remain practically unaffected. The adoption of a velocity dependent friction law explains the force generating behaviour of tyres at high sliding velocities. The analysis is extended to the area of transient tyre behaviour with the development of a tyre model appropriate for the study of transient friction force generation within the contact patch. The model incorporates viscoelasticity and inertial contributions, and incorporates a numerical stick-slip law. These characteristics are combined together for the successful simulation of transient friction force generation. The methodologies developed for the modelling of transient friction and steady-state tyre force generation are combined and further extended in order to create a generic transient tyre model. This final model incorporates a discretised flexible viscoelastic belt with inertia and a separate fully-dynamic discretised tread, also with inertia and damping, for the simulation of actual prevailing conditions in the contact patch. The generic tyre model appears to be capable of performing under a variety of operating conditions, including periodic excitations and transient inputs which extend to the non-linear range of tyre behaviour. For the evaluation of the influence of the aforementioned tyre models on the handling responses of a vehicle, a comprehensive vehicle model is developed, appropriate for use in handling simulations. The two versions of the steady-state models and the generic transient model are interfaced with the vehicle model, and the response of the vehicle to a step-steer manoeuvre is compared with that obtained using the Magic Formula tyre model. The comparison between the responses is facilitated by the definition of a new measure, defined as the non-dimensional yaw impulse. It is found that the transience involved in tyre behaviour may largely affect the response of a vehicle to a prescribed input.
9

The interaction of tyre and anti-lock braking in vehicle transient dynamics

Jaiswal, Manish January 2009 (has links)
The thesis presents an intermediate modelling approach to study transient behaviour of vehicle systems, with emphasis put on simplified yet accurate representation of important system elements. A representative non-linear vehicle model is developed in MA TLAB/Simulink environment, where non-linear characteristics of tyre, suspension and braking system are included to capture the dynamic behaviour of a vehicle under transient conditions. The novel aspect of this work is the application of a representative full vehicle-tyre-ABS integrated set-up to study the complicated interaction between tyre and anti-lock braking, under a range of demanding operating conditions, including combined cornering and braking. The modelling methodology involves development of low end vehicle models, based on the Newton-Euler formulation. Subsequently, an intermediate vehicle model is devised, where more details are incorporated such as additional DOF to capture the sprung mass motion in space, along with its non-linear interactions with the un-sprung masses, large angle effects, kinematics of steering/wheels and an appropriate tyre model suitable for transient manoeuvres. Particular attention is paid to the suspension system modelling, through inclusion of non-linear effects in springs, dampers, bump-stops, and anti-roll bars, along with the jacking and anti-dive effects using the virtual work method. The model also incorporates a hydraulic brake model, based on the reduced order brake system dynamics for realistic simulation of the braking manoeuvres. A complex multi-body ADAMS/Chassis model, with much greater level of detail, has also been established to extensively compare and enhance the realistic behaviour of the intermediate vehicle model. During the simulation exercise, the intermediate vehicle model has shown good agreement with the complex ADAMS model, thus justifying the accurate representation of vehicle.non-linear characteristics, particularly the suspension system. The realistic behaviour of the vehicle model is further ascertained with a reliable GPS enabled test vehicle, by performing number of manoeuvres on test tracks, including combined cornering and braking. A representative 4-channel conventional ABS system is modelled and integrated in the intermediate vehicle model. The ABS adopts generic peak seeking approach, employing wheel deceleration and brake slip as control variables. External braking inputs, in form of stepped pressure pulses, are also separately used to represent the transient braking system dynamics. In the current work, different transient tyre models based on the single point contact approach and using Magic Formula steady-state characteristics are applied, while studying the influence of their dynamic behaviour on the ABS system. By employing a representative ABS system in a multi-body vehicle model and considering the particularly demanding situation of combined braking I cornering, it is shown that the models which are adequate for pure braking might struggle when the complicated full vehicle dynamics are excited. It is shown that the first order relaxation length approach may not be sufficient to fully satisfy the requirements of an ABS braking, especially if the relaxation length is not modelled as a variable dependent on tyre slip. In comparison, the modelling approach, where the carcass compliances and contact patch properties are explicitly represented, can handle the oscillatory tyre behaviour associated with ABS braking, in a far more accurate manner. In comparison to the earlier studies, which were mostly conducted for straight-line braking, this thesis stresses the fact that the tyre behaviour can be influenced by the complex interaction of handling and braking, and hence the effect should be captured while investigating or evaluating the performance of a tyre model in relation with ABS simulation.
10

Analyse des besoins des conducteurs âgés et des adaptations mises en œuvre lors de la réalisation de manœuvres à basses vitesses / Analysis of older drivers’ needs and adaptations during low speed manoeuvres

Douissembekov, Evgueni 14 November 2014 (has links)
Les manoeuvres de stationnement représentent une difficulté pour les conducteurs âgés. De ce fait, elles font partie des situations de conduite les plus évitées chez les séniors. L'étude s'intéresse aux difficultés et aux besoins des conducteurs âgés lors des manoeuvres à basses vitesses. Premièrement, une enquête s'intéressant aux différents aspects de l'activité de stationnement sera réalisée auprès des conducteurs âgés du Rhône. Ensuite, la gestion de ressources cognitives chez le conducteur manoeuvrant sera étudiée dans une série d'expériences avec les différents types de manoeuvres de stationnement. Pour ce faire, des places de stationnement de configuration modifiable seront aménagées dans un parking, et les manoeuvres seront effectuées par les participants. L'étude s'intéresse plus particulièrement à la gestion de la ballance saillance-pertinence lors de l'exploration visuelle de l'environnement du parking. Les informations ainsi obtenues devraient contribuer à la conception des systèmes d'aide aux manoeuvres adaptés aux seniors. / One cannot imagine driving without parking manoeuvres since they mark the beginning and the end of each trip. However, physiological and cognitive decline with ageing can increase the difficulty of parking manoeuvring. Our study is organized in two stages. Firstly, a postal survey investigated the parking behaviour among seniors. It provided information about parking habits, needs and difficulties of older drivers. An approach based on Manchester Driving Behaviour Questionnaire lead us to classify four types of parking errors. We also identified factors contributing to the difficulty of parking manoeuvring.Secondly, we studied parking manoeuvring with experimental vehicle and in a driving simulator. In order to examine attentional processes during manoeuvres, we used the MAM model of attention. The salience and the relevance of elements present in the parking were modified. Parking performance was also examined in relation to drivers’ age and their attentional and visual abilities. The salience and the relevance of parking environments interacted with driver’s age and the extent of their total, peripheral and attentional field of view. Drivers with restricted total, peripheral field or attentional field of view can meet more difficulty during manoeuvres when they must share their attention in complex parking environment. A highly salient obstacle can be more easily detected by these drivers. In the presence of a pedestrian, the difficulty of manoeuvring can increase among drivers with restricted total, peripheral field or attentional field of view and decrease among drivers without such restriction. Further research should provide more information on strategies adopted by older drivers during manoeuvring.

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