Spelling suggestions: "subject:"oon dried"" "subject:"soon dried""
171 |
Artillery and Warfare 1945-2025Bailey, J P A 24 November 2009 (has links)
For millennia battles were essentially affairs of linear encounter. From the 10th
Century to the 20th Century, artillery generally fired directly in the two dimensional
plane,limiting potential effects. The development of indirect fire changed this ,
two-dimensional model. Warfare became not so much a matter of linear encounter
as one of engagement as cross and throughout an area; and artillery dominated land
operations in both the First and Second World Wars as a result.
Firepower was subsequently often applied in even greater weights, but its effects
were frequently excessive and high-value targets proved elusive. During the Cold
War in Europe,the importance of field artillery wanded relative to other arms.
Artillery could only regain its utility by acquiring the highest-value targets and
engaging them effectively with the appropriate degree of force in time and space true
precision, as opposed to mere accuracy at a point. Improvements in target
acquisition and accuracy will enable land systems once more to engage targets
effectively throughout the battlespace with implications for warfare analogous to
those precipitated by the introduction of indirect fire a century ago.
Land operations will become increasingly three-dimensional and Joint. The effects
of fire will increasingly be applied in, not merely via, the third dimensions, since
targets themselves will increasingly be located, not just on the area of a battlefield,
but in the volume of three-dimensional battlespace with values of indetermined
by considerations of the fourth dimension, time. Fire, lethal and non-lethal, will
also be targeted in other less tangible dimensions such as cyber-space and new
types of 'virtual counterfire' will also emerge in the forms of legal and moral
restraint. All will be viewed through the lens of perceptions.
The burgeoning of firepower from all sources now becomes the spur for changes in the relationship between the land and air components, mindful of those novel factors that will increasingly inhibit the application of that firepower.
|
172 |
Modélisation de la fatigue des systèmes de forage de puits à trajectoire complexe / Fatigue modelling of drilling systems applied to complex trajectory wellsDao, Ngoc Ha 13 February 2014 (has links)
Face à la complexité croissante des trajectoires et des conditions opérationnelles des forages pétroliers et géothermiques, le phénomène de fatigue est devenu la cause principale de rupture des garnitures de forage. La fatigue des tiges est essentiellement liée à leur flexion cyclique due à leur rotation dans une section courbe du puits. L'objectif de ce travail est d'élaborer une méthodologie ainsi que les modèles numériques nécessaires pour évaluer la fatigue des tiges au cours du forage de puits à trajectoire complexe. Pour ce faire, nous proposons d'abord de choisir parmi les approches existantes de prévision de la durée de vie en fatigue d'une structure celles qui nous ont semblé les plus pertinentes pour le problème de fatigue des systèmes de forage. Puis, ces approches (qui comprennent les théories de la fatigue et de la rupture ainsi que des lois empiriques), et des logiciels de calcul de structures sont ensuite intégrés dans des algorithmes de calcul incrémental de la fatigue d'un système en fonction de l'évolution de l'opération du forage. Du fait que les contraintes dans les tiges restent souvent dans le domaine élastique, deux modèles de fatigue des tiges sont développés : un premier est basé sur le calcul du cumul de fatigue et un second sur le calcul de la propagation de fissure par fatigue. Ces deux modèles peuvent être utilisés dans la phase de conception de la trajectoire du puits et de la garniture pour le forer, de même qu'en opération pour prédire les risques de rupture par fatigue du train de tiges. Ceci permet à l'opérateur de planifier la gestion des tiges et leurs inspections en fonction de l'historique de leur utilisation. / Facing the growing complexity of trajectories and operating conditions of oil and geothermal drillings, the fatigue phenomenon has become the main cause of drill-string failure. The fatigue of drill-pipes is essentially due to their cyclic bending caused by their rotation in a curved section of the well. The objective of this work is to develop a methodology and the necessary numerical models to assess the fatigue of drill-pipes during drilling operations of complex trajectory wells. For this purpose, we propose firstly to choose among the available approaches for structure fatigue life prediction those that seem most relevant to drill-string fatigue problem. Then, these approaches (which include the fatigue and fracture theories as well as empirical laws), and structural calculation software are then integrated into incremental computation algorithms of drill-pipe fatigue in function of drilling operation evolution. Since the stresses in drill-pipes remain often within the elastic domain, two fatigue models for drill-pipes are developed: the first one is based on the cumulative fatigue calculation and the second one on the fatigue crack growth calculation. These models can be used in the well and drill-string design, or in real time during drilling to predict the fatigue failure in the drill-string. This allows the drill operator to plan the management of drill-pipes and their inspections depending on their usage history.
|
173 |
Drill wear monitoring using instantaneous angular speed : a comparison with conventional technologies used in drill monitoring systemsSambayi, Patrick Mukenyi Kataku January 2012 (has links)
Most drill wear monitoring research found in the literature is based on
conventional vibration technologies. However, these conventional approaches still have
not attracted real interest from manufacturers for multiples of reasons: some of these
techniques are not practical and use complicated Tool Condition Monitoring (TCM)
systems with less value in industry. In addition, they are also prone to give spurious drill
deterioration warnings in industrial environments. Therefore, drills are normally replaced
at estimated preset intervals, sometimes long before they are worn or by expertise
judgment.
Two of the great problems in the implementation of these systems in drilling are:
the poor signal-to-noise ratio and the lack of system-made sensors for drilling, as is
prevalent in machining operations with straight edge cutters. In order to overcome the
noise problems, many researchers recommend advanced and sophisticated signal
processing while the work of Rehorn et al. (2005) advises the following possibilities to
deal with the lack of commercial system-made sensors:
Some research should be directed towards developing some form of
instrumented tool for drill operations.
Since the use of custom-made sensors is being ignored in drilling operations,
effort should be focused on intelligent or innovative use of available sensor
technology.
It is expected that the latter could minimize implementation problems and allows an
optimal drill utilization rate by means of modern and smart sensors.
In addition to the accelerometer sensor commonly used in conventional methods,
this work has considered two other sensor-based methods to monitor the drill wear
indirectly. These methods entail the use of an instrumented drill with strain gauges to
measure the torque and the use of an encoder to measure the Instantaneous Angular
Speed (IAS). The signals from these sensors were analyzed using signal processing
techniques such as, statistical parameters, Fast Fourier Transform (FFT), and a
ii
preliminary Time-Frequency (TF) analysis. A preliminary investigation has revealed that
the use of a Regression Analysis (RA) based on a higher order polynomial function can
very well follow and give prognosis of the development of the monitored parameters.
The experimental investigation has revealed that all the above monitoring systems
are sensitive to the deterioration of the drill condition. This work is however particularly
concerned with the use of IAS on the spindle of the drill, compared to conventional
monitoring systems for drill condition monitoring. This comparison reveals that the IAS
approach can generate diagnostic information similar to vibration and torque
measurements, without some of the instrumentation complications. This similitude seems
to be logical, as it is well known that the increase of friction between the drill and workpiece
due to wear increase the torque and consequently it should reduce or at least affect
the spindle rotational speed.
However, the use of a drill instrumented with a strain gauge is not practical,
because of the inconvenience it causes on production machines. By contrast, the IAS
could be measured quite easily by means of an encoder, a tachometer or some other smart
rotational speed sensors. Thus, one could take advantage of advanced techniques in
digital time interval analysis applied to a carrier signal from a multiple pulse per
revolution encoder on the rotating shaft, to improve the analysis of chain pulses. As it
will be shown in this dissertation, the encoder resolution does not sensibly affect the
analysis. Therefore, one can easily replace encoders by any smart transducers that have
become more popular in rotating machinery. Consequently, a non-contact transducer for
example could effectively be used in on-line drill condition monitoring such as the use of
lasers or time passage encoder-based systems.
This work has gained from previous research performed in Tool Condition
Monitoring TCM, and presents a sensor that is already available in the arsenal of sensors
and could be an open door for a practical and reliable sensor in automated drilling.
iii
In conclusion, this dissertation strives to answer the following question: Which one of
these methods could challenge the need from manufacturers by monitoring and
diagnosing drill condition in a practical and reliable manner? Past research has
sufficiently proved the weakness of conventional technologies in industry despite good
results in the laboratory. In addition, delayed diagnosis due to time-consuming data
processing is not beneficial for automated drilling, especially when the drill wears rapidly
at the end of its life. No advanced signal processing is required for the proposed
technique, as satisfactory results are obtained using common time domain signal
processing methods. The recommended monitoring choice will definitely depend on the
sensor that is practical and reliable in industry. / Dissertation (MEng)--University of Pretoria, 2012. / gm2013 / Mechanical and Aeronautical Engineering / MEng / Unrestricted
|
174 |
Cooling Strategy Influence on Temperature in ETD CenterEdinger, Oskar January 2021 (has links)
Striving for increased productivity while maintaining hole quality and high process robustness when drilling requires knowledge about the working principles of heat generation, mechanics and a proper cutting fluid that aids in cooling, lubricating and evacuating chips from the cutting zone. If the heat generated in the tool-workpiece and tool-chip interfaces does not exit the cutting zone adequately through the chips, the workpiece material or the redistribution of coolant the hole quality can be impacted negatively and breakdowns may occur which reduces overall productivity. During product testing, a sudden type of drill failure was observed when machining 316L stainless steel. When modifying the coolant design this was avoided which led to the assumption that the failure was caused by a large amount of heat being generated due to poor conductivity in the material combined with insuffcient cooling. However, this theory couldn't be investigated because of a lack of an existing method. To evaluate, three modifications of the CoroDrill 870 with dimensions Ø16mm and length 3xD were designed using Siemens NX 12 to observe whether coolant design choices have a significant impact on heat generation when drilling. To examine this a testing methodology was developed which utilizes IR-thermography and a combination of type K and J thermocouples inserted into the workpiece and onto the back surface, which measures its temperature in the cutting zone. Several tests were conducted with the developed setup to gather a larger data set to reduce impact from random error and to perform further analysis. Although the experiment setup is promising due to being simple and applicable to different materials there are large sources of variation associated with the placement of thermocouples. The results indicate some difference in registered temperature between the modifications however it is diffcult to draw conclusions based on the relatively few trustworthy measurements made. / För att förbättra produktiviteten vid borrning utan att kompromissa på hålkvalité och processäkerhet krävs bakomliggande kunskaper inom områden som, värmebildning, skärförlopp, och kylvätska vilket kyler, smörjer, och transporterar spånor från skärzonen. Om värmen som bildas i ytorna mellan verktyg-ämne och verktyg-spåna inte lämnar skärzonen på ett tillförlitligt sätt genom spånor, ämnet eller genom kylvätskans cirkulation kan hålkvalitén påverkas eller haverier kan orsakas vilket minskar produktivitet. Under en testning som genomfördes där 316L rostfritt stål borrades upptäcktes en ny typ av abrupt brott. När borrens kyllösning modiferades kunde detta fel undvikas varpå man drog slutsatsen att haveriet var en konsekvens av den stora temperaturgradient som bildas då materialets värmeledningsförmåga är relativt dålig. Dessvärre kunde denna teori inte prövas då det saknades en befintlig testmetodik. För att undersöka detta utvecklades tre modifikationer av CoroDrill 870 med dimension Ø16mm och längd 3xD i Siemens NX 12 i syfte att observera huruvida en signifikant temperaturskillnad skulle uppstå. För att utreda detta skapades en testuppställning som kombinerar IR-termografi med termoelement av typ K och typ J, fästa i ämnet respektive påämnets baksida vilket mäter materialets temperatur i skärzon. Ett flertal tester genomfördes med denna uppställning för att samla en större mängd data för fortsatt analys samt för att minska inverkan av slumpmässiga fel.Även om metoden är lovande då den är relativt enkel och tillämpbar på olika material så finns det stora potentiella källor till variation kopplade till mänsklig faktor och placering av termoelement. Resultatet som analyserats antyder att det finns en viss temperaturskillnad mellan modifikationerna men för att göra välgrundade slutsatser skulle fler mätningar behöva genomföras.
|
175 |
CNC řízení frézky / Milling machine CNC controlKrejčí, Jan January 2021 (has links)
This diploma thesis deals with rebuild of manual drill-mill machine BF20L into CNC mill machine, 3D model of that and eventual control using PLC. All axes are powered by stepper motors, with encoders, connected to control cards and industrial computer from company Beckhoff. For this control is made full switchboard, supplemented by electrical wiring diagram. Program control along with visualization is made in software TwinCAT 3. Drill-mill machine can be controlled manually or automatically by program.
|
176 |
Zajištění náhradních zdrojů vody obklíčené nemovité věci v cizím areálu / Provision of alternative water sources for a real estate surrounded by foreign propertyKukol, Jan January 2015 (has links)
The first part of this thesis is focused on water wells and their classification. A big part of this thesis is an essay on groundwater. This thesis also examines the various technical parts of drilled wells and dug wells. The design of pump is discussed briefly. The second part of this thesis is focused on objective and financial complexity of proposed solutions.
|
177 |
Porovnání efektivity bruslení rozvíjené drillovou a herní formou u věkové kategorie U - 10 / The comparison of ice skating efficiency developed by drill vs. gaming form in the U - 10 categoryDvořák, Luboš January 2020 (has links)
Title: The comparison of ice skating efficiency developed by drill vs. gaming form in the U - 10 category. Objectives: The aim of this dissertation is to compare the efficiency of skating developed by drill and game forms of training using speed-skill tests for ice hockey players under the age of 10. Methods: This work used the method of quantitative analysis of test results for ice hockey players of the U10 age category. The tested group consisted of 18 players of the U10 age category from the HC Hvězda Praha team. The dissertation includes three stages of data collection. The first set of data is preliminary, the second set of data is collected after the intervention by the drill form of training and the third set of data is collected after the intervention by the game form of training. The development of skating skills in drill and game form of training always took place in the first twenty minutes of the training. The obtained sets of data were recorded and then evaluated in accord with Friedmanan and Wilcoxon tests. Results: In the 6.1 m sprint, the 35 m sprint and the S-Corner test, slalom with a puck test and the crossing with a puck test there was recorded improvement after each intervention. In the crossing without a puck test the difference was recorded only after the drill form of...
|
178 |
Modeling of a Hydraulic Rock Drill for Condition Monitoring / Modellering av en hydraulisk slagborrmaskin för tillståndsövervakningKagebeck, Adam, Najafi, Mahdi January 2022 (has links)
This thesis aims to investigate the possibility of using a mathematical model to detect several common faults in a hydraulic rock drill. To this end, a parameterized state space model of the hydraulic drill, which simulate its behavior, is created. The model parameters are divided into two categories where different estimation methods are used to determine their values. The first category consists mainly of the parameters that are assumed to be invariant and independent of the various operating conditions. Experimental data are used to estimate these parameters. The other category is the variables that change depending on the machine’s current condition and operating settings. These include the response from the rock and internal leakages in the hydraulic drill. These parameters are estimated by integrating the impact piston position measurements in the simulation algorithm. The model is simulated for different fault modes, and the resulting estimated parameters are studied. It is shown that the resulting distributions for some of the estimated parameters differ between the fault modes, which makes fault detection possible. Furthermore, a condition monitoring system based on the estimated parameters provided by the model is designed and evaluated. It is shown that the performance and the robustness of the monitoring system depend on the machine’s operating settings and condition, where the system performs best for an operating pressure of 220 bar and the internal cylinder leakages.
|
179 |
Reconstructing long term sediment flux from the Brooks Range, Alaska, using edge clinoformsKaba, Christina Marie January 2004 (has links)
Thesis (S.M.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and, the Woods Hole Oceanographic Institution), 2004. / Includes bibliographical references (p. 37-40). / Laterally extensive, well-developed clinoforms have been mapped in Early Cretaceous deposits located in the northeastern 27,000 km2 of the Colville Basin, North Slope of Alaska. Using public domain 2-D seismic data, well logs, core photographs, and grain size data, depositional geometries within the Nanushuk and Torok formations were interpreted in order to constrain the transport conditions associated with progradation of the shoreline and construction of the continental margin out of detritus shed from the ancestral Brooks Range. Using STRATA, a synthetic stratigraphic modeling package, constructional clinoform geometries similar to those preserved in the North Slope clinoform volume (32,400 km3) were simulated. Sediment flux, marine and nonmarine diffusivities, and basin subsidence were systematically varied until a match was found for the foreset and topset slopes, as well as progradation rates over a 6 million year period. The ability of STRATA to match the seismically interpreted geometries allows us to constrain measures of possible water and sediment discharges consistent with the observed development of the Early Cretaceous clinoform suite. Simulations indicate that, in order to reproduce observed geometries and trends using constant input parameters, the subsidence rate must be very small, only a fraction of the most likely rate calculated from the seismic data. Constant sediment transport parameters can successfully describe the evolution of the prograding margin only in the absence of tectonic subsidence. However, further work is needed to constrain the absolute magnitude of these values and determine a unique solution for the NPR-A clinoforms. / by Christina Marie Kaba. / S.M.
|
180 |
Automatiserad fotografering av verktygsförslitning med robot / Automated photography of tool wear using a robotMörk, Albin January 2023 (has links)
Vid skärande bearbetning av material för att framställa olika produkter med önskade egenskaper orsakas förslitningar av verktygen som är viktiga att fotografera och analysera för att uppskatta livslängden. Detta kräver erfaren personal med precision som är svår att upprepa där automation kan vara en lösning för att avlasta personal från ett monotont arbete. Syftet med studien är att bidra med kunskap om hur man kan fotografera förslitningen av verktyg med hjälp av automation och ge förslag på en lösning. För att komma med ett lösningsförslag har en nulägesanalys genomförts med hjälp av observationer och intervjuerhos Sandvik Coromant, litteratursökning för att undersöka vad som gjorts inom området redan och simuleringar. Resultatet blev ett konstruktionsförslag för en kamerafixtur och cykeltider för att fotografera samtliga förslitningsområden för de testade verktygen i ett simuleringsprogram. Om lösningsförslaget ska implementeras i verkligheten kommer den behöva testas för att med säkerhet kunna fotografera med tillräckligt bra fokus och ljussättning samt att kamerafixturen inte blir för skakig vid rörelse med roboten. / The use of cutting tools in cutting processing cause tool wear which need be analysed and photographed to predict tool life. To analyse the tool wear you need technicians with experience with precision that is hard to repeat in which automation could be a solution. The purpose of this study is to contribute with knowledge on how you could photograph tool wear using automation and suggest a solution. This was done with a current situation analysis with the use of observation and interview of the technicians at Sandvik Coromant. A literature study was conducted to gather information about what has been done earlier in this field. Later a suggestion on the design of the camera fixture was made and simulated in a simulation program with the robotic cell to ensure it is possible to implement in real life. The result from the study suggests that the camera fixture with the current robotic cell is capable of automatically photograph the tool wear of the tested tools. If the suggested camera fixture should be implemented in real life it needs to be tested with the camera to confirm it gets good enough focus and lightning inside the CNC-machine. It also needs to be tested so it does not wobble to much with the usage of the robot.
|
Page generated in 0.0579 seconds