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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.
131

S. Table : A self stabilising and body borne table / S. Table : Ett självstabiliserande och kroppsburet bord

Engman, Jacob, Gustavsson, Lucas January 2023 (has links)
This project aimed to create a prototype of a self stabilising and body borne table. The prototype was constructed by first building a CAD-model and doing a simulation of the entire system. This provided a ground for doing a physical construction. An Arduino Uno was used as a microcontroller that sent signals to two servo motors based on data from an accelerometer. This way, as the system was tilted to one side, the motors would compensate for this and put the table horizontal again. The purpose of the report was to examine how a multiaxial system could be controlled and how a plane can be stabilised based on the fact that a plane is made up of three points in space. Additionally, another purpose was to see how a simulation differs from a physical prototype and why. The constructed prototype worked as intended and gave similar results as the simulation, although with minor differences due to the simulation being done in a perfect environment. Finally, the sources of the imperfections are discussed along with what future work needs to be done on the prototype if it were to become a product. / Detta projekt hade som mål att tillverka ett självstabiliserande och kroppsburet bord. Prototypen byggdes genom att först göra en modell i CAD samt en simulering av hela systemet. Detta gav en grund för att sedan kunna göra en fysisk konstruktion. En Arduino Uno användes som en mikrokontroller som skickade signaler till två stycken servomotorer baserat på data från en accelerometer. På detta sätt, när systemet lutades åt något håll kunde motorerna kompensera för detta och sätta bordet horisontellt igen. Målet med rapporten var att undersöka hur ett multiaxiellt system kunde styras samt hur ett plan kan stabiliseras baserat på att tre punkter i rymden utgör ett plan. Utöver det fanns också målet att se hur en simulering och en fysisk prototyp varierar och varför. Den byggda prototypen fungerade som planerat och gav liknande resultat till simulering, dock med små skillnader på grund av att simuleringen gjordes i ett perfekt tillstånd. Slutligen diskuterades felkällorna och vad som skulle behöva göras i framtiden om fortsatt arbete skulle göras på prototypen och förvandla den till en produkt.
132

Sharkbait - A self-stabilising underwater drone : Evalution of response time, propulsion and steering in a underwater environment / Sharkbait - en självstabiliserande undervattensdrönare

Hanefors, Victor, Rahmanian, Shaya January 2019 (has links)
This projects purpose was to build an underwater remote operated vehicle with software controlled self-stabilisation for evaluation of the response time, propulsion and steering to see what could be achieved. A prototype was constructed and tested in dry conditions at first. The prototype features an Arduino and a Raspberry Pi as control units, controlling six thrusters. With the help of a controller the user can manoeuvre the vehicle and when exposed to unexpected forces sensors detect this allowing the software to counteract it. Due to risk of massive electrical failure as a result of failed waterproofing tests underwater were postponed until the end. Unfortunately this made full optimisation of the software difficult. The results in a dry enviroment were positive, the system was able to fully perform the desired outputs at the thrusters, the PID controller kicked in when it detected a disturbance in its position. Testing the propulsion system in the water gave positive results as well, the propeller held and the motor kept working while submerged. The response time performed adequately at an average of 50ms. / Detta projektets syfte var att bygga en fjärrstyrd undervattensdrönare med mjukvarustyrd själstabilisering för utvärdering av responstid, framdrivningen, och styrningen för att se vad som går att uppnå. En prototyp byggdes och testades först i torra förhållanden. Prototypen har kontrolleras med en Arduino och en Raspberry Pi, som styr sex drivmotorer. Genom en kontroller kan användare styra farkosten och om den utsätts för oväntade krafter kan mjukvaran motverka dom. På grund av risken för massivt elhaveri om vattentätningen inte är tillräcklig sköts tester i vatten upp. Tyvärr gjorde detta att fullständig optimering av mjukvaran blev svår. Resultaten i torr miljö var positiv, systemet utförde sin önskade funktion vid motorerna, och PID kontrollern försökte ställa om positionen till rätta när den märkte av en felaktig position. Propulsion systemet testades i vatten och gav positiva resultat också, propellern höll och motorn fortsatte fungera fastän sänkt i vatten. Responstiden gav ett adekvat utfall på ungefär 50 ms.
133

Evaluation of Video Stabilisation Algorithms in Dynamic Capillaroscopy / Utvärdering av videostabiliseringsalgoritmer inom dynamisk kapilläroskopi

Wilhelmsson, Oskar January 2018 (has links)
In the field of dynamic capillaroscopy, measurements of the capillary blood cell velocity (CBV) give significant insight into the human body. For instance, diabetes, hypertension and peripheral arterial occlusive disease all affect CBV. However, the videos used to measure CBV – captured with a microscope – are often displaced in relation to the microscope by small motions of the finger or toe. Stabilisation algorithms are commonly used to reduce this problem, in order to carry out measurements such as CBV using the stabilised video. Artificial capillaroscopy videos were used to compare the stabilisation algorithms Mutual information, Single-step DFT, Block matching and Phase correlation in terms of computational time; RMSE, PSNR and MSE; and resistance to blurring effects. Single-step DFT was indicated to be the best suited algorithm in all aforementioned metrics. / Inom dynamisk kapilläroskopi ger mätningar av kapillär blod-cell hastighet (CBV) signifikanta insikter inom den mänskliga kroppen. Till exempel, diabetes, hypertoni och perifer arteriell ocklusiv sjukdom påverkar CBV. Däremot är videorna som används för att mäta CBV – tagna med ett mikroskop – ofta förskjutna i relation till mikroskopet på grund av små rörelser av ett finger eller en tå. Stabiliseringsalgoritmer används vanligen för att reducera detta problemet med avsikt att därefter använda den stabiliserade videon för att mäta viktiga egenskaper, som till exempel CBV. Artificiella kapilläroskopivideor användes för att jämföra stabiliseringsalgorithmerna Mutual information, Single-step DFT, Block matching and Phase correlation inom beräkningstid; RMSE, PSNR och MSE; och resistens mot suddighet. Single-step DFT indikerades som den bäst lämpade algoritmen inom de ovannämnda måtten.
134

Coin: the missing currency in peace support operations and beyond

Pinder, David January 2007 (has links)
The United Nations has a long history of peacekeeping missions. These have evolved over time but since the end of the Cold War there has been rapid growth in those missions where the remit placed on the peacekeepers, both military and civilian, is more complex and demanding. In trying to define these missions and their mandates a wide range of terminology has been developed in an effort to describe the exact nature of the mission. Since many of these deployments take place into theatres where there is no peace to keep, or where a fragile peace reverts to a conflict situation such tight definitions often lead to the troops involved no longer having an appropriate mandate. More recently some of these larger missions constitute in fact interventions to impose peace. Attempts to find a `peace¿ classification for such deployments often confuse the issue rather than bring clarity. In reality these missions are not peacekeeping at all. The almost forgotten doctrine, principles and practices of Counterinsurgency provide a better framework for defining these missions, the respective roles of the key players and the factors necessary to bring success.
135

Assessment of lime-treated clays under different environmental conditions

Ali, Hatim F.A. January 2019 (has links)
Natural soils in work-sites are sometimes detrimental to the construction of engineering projects. Problematic soils such as soft and expansive soils are a real source of concern to the long-term stability of structures if care is not taken. Expansive soils could generate immense distress due to their volume change in response to a slight change in their water content. On the other hand, soft soils are characterised by their low shear strength and poor workability. In earthwork, replacing these soils is sometimes economically and sustainably unjustifiable in particular if they can be stabilised to improve their behaviour. Several techniques have evolved to enable construction on problematic soils such as reinforcement using fibre and planar layers and piled reinforced embankments. Chemical treatment using, e.g. lime and/or cement is an alternative method to seize the volume change of swelling clays. The use of lime as a binding agent is becoming a popular method due to its abundant availability and cost-effectiveness. When mixed with swelling clays, lime enhances the mechanical properties, workability and reduces sensitivity to absorption and release of water. There is a consensus in the literature about the primary mechanisms, namely cation exchange, flocculation and pozzolanic reaction, which cause the changes in the soil characteristics after adding lime in the presence of water. The dispute is about whether these mechanisms occur in a sequential or synchronous manner. More precisely, the controversy concerns the formation of cementitious compounds in the pozzolanic reaction, whether it starts directly or after the cation exchange and flocculation are completed. The current study aims to monitor the signs of the formation of such compounds using a geotechnical approach. In this context, the effect of delayed compaction, lime content, mineralogy composition, curing time and environmental temperature on the properties of lime-treated clays were investigated. The compaction, swelling and permeability, and unconfind compression strength tests were chosen to evaluate such effect. In general, the results of the geotechnical approach have been characterised by their scattering. The sources of this dispersion are numerous and include sampling methods, pulverisation degree, mixing times and delay of compaction process, a pre-test temperature and humidity, differences in dry unit weight values, and testing methods. Therefore, in the current study, several precautions have been set to reduce the scattering in the results of such tests so that they can be used efficiently to monitor the evolution in the properties that are directly related to the formation and development of cementitious compounds. Four clays with different mineralogy compositions, covering a wide range of liquid limits, were chosen. The mechanical and hydraulic behaviour of such clays that had been treated by various concentrations of lime up to 25% at two ambient temperatures of 20 and 40oC were monitored for various curing times. The results indicated that the timing of the onset of changes in mechanical and hydraulic properties that are related to the formation of cementitious compounds depends on the mineralogy composition of treated clay and ambient temperature. Moreover, at a given temperature, the continuity of such changes in the characteristics of a given lime-treated clay depends on the lime availability.
136

Mellanrum

Hölbling, Markus, Carlquist, Ellen January 2013 (has links)
I den här uppsatsen har vi undersökt hur trottoarens materiella ut- formning påverkar uppkomsten av mellanrum. Mellanrum är ett både tidsligt och rumsligt fenomen som kan uppstå i ett dynamiskt publikt rum.Vi har observerat fyra trottoarer inom Malmös stadskärna och under- sökt hur materiella faktorer på och vid trottoaren påverkar vilka aktivite- ter som äger rum på platsen.Uppsatsens övergripande forskningsfråga är: Hur påverkar trottoa- rens materiella utformning uppkomsten av mellanrum?Under observationerna har vi undersökt: Vilka materiella egen- skaper finns på trottoaren och hur påverkar de den territoriella komplexi- teten? samt Vilka omgivande faktorer ger upphov till en territoriell kom- plexitet på trottoaren?Syftet med uppsatsen är att lyfta fram trottoaren som ett viktigt pu- blikt rum där det oförutsägbara kan ta plats.Ett av uppsatsens nyckelbegrepp är territoriell komplexitet [Kär- rholm 2004, 2012] då chansen att mellanrum uppstår är som störst på plat- ser med hög territoriell komplexitet.Våra teoretiska utgångspunkter utgörs av Mattias Kärrholms ter- ritorialitetsbegrepp [2004] och stabiliseringsprocesser [2012] samt Emma Nilssons diskussion kring materiell figur och rumskategorier [2010].Kulturhistoriska stöd har vi hämtat från Anastasia Loukaitou- Sideris & Renia Ehrenfeucht [2009] som bland annat skildrar en växande privatisering och utökand kontroll av stadens publika rum.En slutsats är att mellanrum kan liknas vid territoriell taktik och app- ropriation som sker på en plats där användandet av platsen inte stöds av den territoriella strategin. / In this study we have researched how the material design of sidewalks affect interstitial space. Interstitial space as phenomena is both temporal and spatial and can occur in a dynamic public space.We have observed four sidewalks in Malmö’s city centre and examined how the substantive elements on and around the sidewalks affect the ac- tivities that takes place.The paper’s main research question is: How does the material design of sidewalks affects interstitial space?During the observations, we have examined: Which material properties occur on the sidewalk, and how do they affect the territorial complexity? and What ambient factors create a territorial complexity on the sidewalk?The purpose of this paper is to highlight the sidewalk as a vital public space where the unpredictable can take place.One of the key concepts is territorial complexity [Kärrholm 2004, 2012] since the chance of interstitial space to occur is more likely in areas with high territorial complexity.Our theoretical premises consists of Mattias Kärrholm’s concepts of territoriality [2004] and stabilization [2012] and Emma Nilsson’s discus- sion on material body and room categories [2010].Cultural support is obtained from Anastasia Loukaitou-Sideris and Renia Ehrenfeucht [2009] who for instance describes a growing pri- vatization and control of the public spaces in the city.One conclusion is that interstitial space can be compared to territorial tactics and appropriation that occur in a place where the activity is not sup- ported by the territorial strategi.
137

Crystal and Particle Engineering: Pharmaceutical Cocrystals through Antisolvent and Liquid-Liquid Phase Separation Technologies

Sajid, Muhammad A. January 2019 (has links)
The effects of polymer concentration and solvents on cocrystal morphology of low solubility drugs were investigated, both of which had an impact. The melting temperatures also decreased with increasing polymer concentration. Placing the binding agent, benzene, at different interfaces induced morphological changes, such as formation of porous cocrystals. Previously liquid-liquid phase separation (LLPS) has been reported as a hindrance in the crystallisation process impeding further development. A phase diagram was constructed, and different phases were categorised into 4 types. After separation of the highly concentrated amorphous Oil Phase II, it was prone to gradual crystallisation. Crystallisation took place over 30-60 minutes; this allowed the in-situ monitoring. A novel cocrystallisation technique was developed; from (LLPS). Cocrystals of indomethacin with saccharin and nicotinamide were obtained by mixing Oil Phase II with the coformers. In-situ monitoring by spectroscopic had gradual changes in spectra; characteristic peaks increased in height and area with the formation of crystals until the reaction was complete. With crystal formation, the XRD spectra gradually had a sharper baseline due to a decrease in the amorphous indomethacin. The photoluminescence (PL) spectra displayed several peaks coupling into one large hump together with increasing intensity as the sample crystallised. There was a shift in the peak absorbance of the pure drug crystals obtained from LLPS and the indomethacin:saccharin cocrystal obtained from LLPS. Amorphous stabilisation was achieved by mixing polymer (PVP) with Oil Phase II. There were no changes to the XRD diffractogram as the sample did not undergo crystallisation.
138

The Impact of moisture and clay content on the unconfined compressive strength of lime treated highly reactive clays

Muhmed, A., Mohamed, Mostafa H.A., Khan, A. 06 September 2022 (has links)
Yes / This study aims to provide a thorough evaluation for the changes in the microstructure and evolution of strength of highly reactive clays that were treated with 7 % lime over a period of curing time as a function of the mixing moisture content. Three series of testing were carried out on specimens with 100 %, 85 % and 75 % of bentonite content and prepared with different moisture content of 10, 20, 30 and 40 % above the corresponding optimum moisture content. Specimens of 100 % bentonite were treated with 7 % of lime, compacted to achieve a predetermined dry unit weight and cured at temperatures of 20 OC and 40 OC for up to 28 days whereas the specimens with 85 % and 75 % of bentonite content were prepared by the addition of sand and were cured at 20 oC for up to 7 days. Unconfined Compressive Strength tests and Scanning Electron Microscopy were conducted to observe the strength and the microstructural changes resulting from increasing mixing moisture content. California Bearing Ratio and Resilient Modulus were correspondingly determined based on correlations with the Unconfined Compressive Strength. The failure pattern was also studied to better understand the ultimate behaviour of lime stabilised clays. The results revealed that the strength of treated bentonite increased with the increase in the moisture content up to 30 % above the corresponding optimum moisture content and with increasing the curing time and temperature. Nevertheless, substituting bentonite with sand on the specimen resulted in a significant reduction on the attained strength. Furthermore, the results of California Bearing Ratio and Resilient Modulus showed that values for both parameters are significantly enhanced with lime treatment. The microstructural analysis provided visual evidence to the improved strength in which the pozzolanic reaction was found to be significantly affected by the amount of moisture in the mixture. The results suggested that compacting lime treated expansive clays with moisture content moderately higher than the optimum moisture content would result in a significant enhancement to the attained strength over the period of curing.
139

TRANSFORMING WASTES AND INDUSTRIAL BYPRODUCTS INTO SUSTAINABLE CONSTRUCTION MATERIALS FOR PAVEMENT SUBGRADE LAYERS

Fayemi, Joshua Ayobami 01 August 2024 (has links) (PDF)
Waste generation is a constant activity of daily life, encompassing a wide variety including municipal, hazardous, industrial, agricultural, medical, radioactive, and mining waste, as well as sewage sludge. The purpose of this study is to concentrate on utilizing industrial waste, which adversely affects our environment, for use in engineering construction projects. This aims to evaluate the enhancement in both the soil’s index and engineering properties. In most civil engineering projects, the underlying soils are often unsuitable for construction purposes. Some of these soils experience significant volume changes due to moisture variations, leading to damage and instability of structures and infrastructure built on them. The complete removal and replacement of such high plastic clay and expansive soils is not always a cost-effective solution. Therefore, there's a pressing need to improve their utility by stabilizing them through eco-friendly and sustainable methods.The present research employs five industrial waste materials to enhance the clayey soil available in Carbondale, Illinois. These waste materials include Lime Sludge (LS), Lime Kiln Dust (LKD), Fly Ash (FA), Ground Granulated Blast Furnace Slag (GGBS), and Cement Kiln Dust (CKD). Lime Sludge and Lime Kiln Dust were mixed with the soil at proportions of 2%, 4%, 6%, and 8%. In contrast, Fly Ash and Cement Kiln Dust were used at higher ratios of 8%, 16%, 24%, and 32%. Lastly, Ground Granulated Blast Furnace Slag was added at levels of 5%, 10%, 15%, and 20%, all based on the soil's dry unit weight. The samples were prepared for Unconfined Compression Strength (UCS) and Resilient Modulus (RM) based on the Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) data obtained from miniature Proctor test. These specimens underwent a 14-day curing period, sealed in plastic film and Ziploc bags, and were stored in a controlled water tub at room temperature. The UCS value for the untreated Carbondale soil was 320 kN/m2. The results indicated that with higher content of Lime Kiln Dust (LKD) and Cement Kiln Dust (CKD), the UCS strength tends to increase with CKD exhibiting the most desirable strength characteristics. The UCS value for 8% LKD was 1377.70 kN/m2 i.e., 330.52% increase. While the UCS improvements for 5% GGBS is 51.32% and 6% Lime Sludge (LS) is 51.65% with no significant enhancements, these waste materials can be more effective as modifiers. Furthermore, the study revealed that the optimal quantity of Class F fly ash for soil stabilization is 8% by dry unit weight with UCS value of 486.46 kN/m2 resulting in 52.01% increase in UCS strength, exceeding this percentage might cause reduction in strength. The highest UCS strength was obtained with 24% CKD at 3263.14 kN/m2 which corresponds to 919.70% increase when compared to the untreated soil. The results of the Resilient Modulus (RM or Mr) test indicate that the incorporation of additives to untreated Carbondale soil significantly improved its stiffness characteristics and resistance to different load cycles on the subgrade. However, the soil treated with GGBS showed a decrease in stiffness. The Resilient Modulus values ranged from 2% to 70% for LS, 47% to 128% for LKD, 4% to 35% for FA, 90% to 243% for CKD, and -16% to 0.3% for GGBS for different confining pressures. The regression analysis, using the Uzan (1985) model, showed R² values of 0.910, 0.838, 0.803, 0.871, 0.773, and 0.809 for Carbondale soil, Carbondale soil mixed with 6% LS, 8% LKD, 8% FA, 5% GGBS, and 24% CKD, respectively. These results confirm the reliability of the test, as all samples except the GGBS-treated one have R² values greater than 0.800. Additionally, consolidation tests were conducted to assess the compressibility characteristics of the additives in the soil. The selected samples were those with the mix proportions that yielded the highest UCS strength for each additive. These samples were meticulously prepared based on the moisture-density relationship obtained from the miniature Proctor test and were subjected to loading and unloading in a specific sequence. The results indicated an increase in the Compression Index (Cc) for mixtures with LS, LKD, FA, and CKD. Conversely, the mix containing GGBS displayed a reduction in the Compression Index (Cc). The Carbondale soil stabilized with 6% LS can be used for subbase stabilization as the UCS strength is greater than 345 kPa. Also, 2 to 8% LKD content can be used for subbase and base course stabilization. 8% FA without any activator can be used for subbase stabilizer. GGBS can be used for subbase soil stabilization and finally CKD can be used for both subbase and base course stabilization.
140

Conception d'une monture stabilisatrice pour un télescope embarqué sur ballon stratosphérique

Côté, Olivier 25 March 2024 (has links)
Dans ce mémoire, il est question de la conception d'une monture stabilisatrice pour un télescope monté sur un ballon stratosphérique. Ce projet de maîtrise s'inscrit dans le cadre du projet HiCIBaS qui vise à faire de l'imagerie haut contraste pour l'observation d'exoplanètes. Essentiellement, ce projet vise à produire une monture qui peut aligner un télescope commercial de 14 po avec une étoile cible avec une précision de plus ou moins 5 secondes d'arc crête à crête. Cette tolérance correspond au champ de vue du système optique rattaché à ce télescope. Le design choisi est celui d'une monture altitude-azimut avec un miroir de repliement Nasmyth. Le miroir de repliement permet de rediriger la lumière vers le système optique sans avoir à l'accrocher directement à la sortie du télescope. Les résultats de stabilisation en laboratoire n'ont pas donné les résultats escomptés étant donné la présence d'un jeu dans les moteurs adaptés à travailler dans des conditions de froid intense. Néanmoins, le contrôleur conçu dans le cadre de ce projet a permis de réduire l'intensité d'une perturbation à 0.7 Hz d'un facteur 5 environ. La fréquence de 0.7 Hz représente la fréquence de dandinement de la nacelle CARMEN dans laquelle le système était installé. Dans ce mémoire, quelques recommandations sont proposées pour améliorer le concept du système de pointage. La première est de ne pas adapter les moteurs pour résister au froid, mais plutôt de les chauffer pendant la nuit d'observation. Le contrôle des moteurs devrait aussi être fait en vitesse plutôt qu'en position. Une dernière recommandation serait d'ajouter un gyromètre en boucle ouverte afin de pouvoir atténuer une partie de la perturbation sans l'aide du contrôleur.

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