• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 42
  • 38
  • 16
  • 10
  • 9
  • 3
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 139
  • 31
  • 26
  • 24
  • 20
  • 18
  • 18
  • 18
  • 16
  • 16
  • 16
  • 14
  • 14
  • 13
  • 12
  • 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.
101

Biomechanický model interakce ventilace a oběhu za podmínek umělé plicní ventilace / Biomechanical model of interaction between ventilation and hemodynamics induced by mechanical ventilation

Otáhal, Michal January 2019 (has links)
MUDr. Michal Otáhal Biomechanický model interakce oběhu a ventilace za podmínek UPV Abstract: Conventional mechanical ventilation provides gas exchange in conditions of respiratory failure by application positive airway pressure in the respiratory system. Due to the significant change in pressure conditions inside the thorax during conventional artificial ventilation the circulation can be significantly affected. Recruitment maneuver (RM) techniques can be a part of ventilation strategy in patients with the Acute Respiratory Distress Syndrome (ARDS), that are used to re-aerate collapsed parts of the lung parenchyma. During these RMs a significantly higher airway pressure is used than in protective ventilation strategy, which can limit the flow through the lung capillary network and can significantly affect the systemic hemodynamics of the patient. The aim of this work was to develop an optimized animation model of ARDS, then to compare the influence that has the application of different types of recruitment maneuvers on hemodynamics and to create a biomechanical simulation model of interaction and blood circulation and its verification with data obtained during the implementation of different types of RM in the experimental animal ARDS model. Results from the experimental animal model and simulations...
102

Mellanchefers upplevelse av deras yrkesroll inom en byråkratisk organisation : med särskild fokus på krav, kontroll och stöd / Middle managers experience of their professional role within a bureaucratic organization : with special focus on requirements, control and support

Blerina, Lyta, Radhika, Patel January 2022 (has links)
Fokus för den kvalitativa studien är att undersöka mellanchefers upplevelse inom vård och omsorg i en byråkratisk organisation med särskild fokus på krav, kontroll och stöd. Vi har intervjuat 8 enhetschefer som jobbar inom en byråkratisk organisation, respondenterna har svarat på frågor gällande vilka upplevelser de har kring deras arbetssituation. Våra intervjuer gjordes på ett semistrukturerat sätt. På grund av det stora avståndet mellan oss uppsatsförfattare har vi valt att utföra 4 intervjuerna var. Resultatet visar att samtliga respondenter känner att de har stora krav från samhället, medarbetarna och ledningen. De menar att kraven har ökat med tiden och fortsätter öka som ett resultat av samhällets utveckling. Utöver kraven känner de också att de har kontroll över sitt arbete mestadels av tiden, men att det ibland finns stressiga perioder där de upplever att dygnets alla timmar inte räcker till. Vi ställde frågan om de upplever att de får stöd i sitt arbete, vilket de upplevde. De får stöd i form av administrativt stöd eller i form av olika gruppchefer. Samtliga respondenter visade stor tacksamhet till det stöd som de får. Utöver kraven som förväntas av mellanchefer i arbetet har vi även valt att ta upp kraven som sätts på individens hantering av känslor, i uppsatsen har vi valt att kalla det emotionell aktivitet. Alla respondenter upplevde att de någon gång behöver gå in i roll för att kunna hantera en viss situation på jobbet. Sammanfattningsvis har vi kommit fram till att trots att mellanchefer har höga krav, har de även hög kontroll inom en byråkratisk organisation. Enligt Karasek och Theorells (1990) krav, kontroll och stödmodell hamnar mellanchefer i kategorin för aktivt arbete, vilka löper stor risk för trötthet och utbrändhet. / This qualitative study has focused on examining the middle managers' self-perceived situation in a bureaucratic organization, with a special focus on the experience of demands and control. We have interviewed 8 middle managers who have worked within a bureaucratic organization, where the respondents have answered eg number of questions regarding their self-perceived situation. Our interviews were conducted in a semi-structured manner. Due to the large distance between us writers, we have chosen to conduct the interviews on our own. The results show that all respondents feel that they have great demands from society, employees, management, etc. They believe that the demands have increased over time and that it continues to increase because we live in such a society. In addition to the requirements, they also feel that they have control over their work most of the time, but that sometimes there are stressful periods where they feel that all hours of the day are not enough. We were asking if they feel that they receive enough support in their work, which they experienced. They receive support in the form of administrative support or in the form of various group leaders. All respondents showed great gratitude for the support they receive. In addition to requirements that are expected of one in the work, we have also chosen to address the requirements that are placed on the individuals emotional activity. All respondents felt that at some point they need to enter into such a professional role in order to be able to handle a certain situation at work. In summary, we have come to the conclusion that despite high demands, you have high control as a middle manager in a bureaucratic organization. According to Karasek and Theorell (1990) requirements and control model, they fall into the category of active work, which runs the risk of being burnt out and fatigue.
103

Evaluating the effectiveness of collisionavoidance functions using state-of-the-artsimulation tools for vehicle dynamics

Sengupta, Abhinav, Gurov, Alexey January 2013 (has links)
The main goal of this work is to gain knowledge of how and to what extent state-of-the-artsimulation tools can be used in a conceptual development phase for vehicle dynamics control atVolvo Car Corporation (VCC).The first part of the thesis deals with an evaluation of vehicle dynamics simulation tools and theiruses. The three simulation tools selected for the study, namely Mechanical Simulation CarSim 8.2.1,IPG CarMaker 4.0.5, and VI-Grade CarRealTime V14, are briefly described and discussed. In order toevaluate and compare these tools with respect to application for vehicle dynamics control, a criterialist is developed covering aspects such as tool requirements and intended usage. Based on thecriteria list and certain identified drawbacks, a ranking of the tools is made possible. Furthermore,the process of developing vehicle models for the different tools is discussed in detail, along with theprocedure of validating the vehicle models.In the second part, the concept of Collision Avoidance Driver Assistance (CADA) function isintroduced and possible approaches for developing CADA functions are discussed in brief. It isimportant to note that the CADA functions in this work are based on cornering the vehicle i.e.maneuvering around the threat, rather than solely reducing vehicle speed. A number ofimplementations of the functions are developed in Simulink. A frequency analysis of a simplifiedlinear vehicle model is performed to investigate the influence of steering, differential braking, andtheir combination on the resultant lateral displacement of the vehicle during an evasive maneuver.The developed CADA functions are then simulated using the vehicle simulation tools. Two specificmetrics - Lateral Displacement gain and DeltaX - are formulated to evaluate the effectiveness of theCADA functions. Based on these metrics, the assistance obtained due to the functions for a specificevasive maneuver is compared.From the evaluation process of the three tools, two were considered suitable for the purpose ofsimulating collision avoidance functions. The evaluation of the CADA functions demonstrates thatcombined assistive steering with differential braking provides considerable assistance in order toavoid collisions. The simulation results also present interesting trends which provide a usefuldirection regarding the conditions for intervention by such collision avoidance functions during anevasive maneuver. The use of simulation tools makes it possible to observe these trends and utilizethem in the development process of the functions.
104

Värdering av minor för mekaniserad strid / Assessment of landmines in mechanized battle

Bengtsson, Fred January 2021 (has links)
Stridsvagnsminans utveckling i helhet har under de senaste 20 åren mer eller mindre stått still. I försvarsberedningens slutrapport Värnkraft beskrivs fördröjande fältarbeten med minor som ett av de prioriterade områdena för Försvarsmaktens ingenjörförband. Med denna prioritering finns ett syfte att undersöka hur vidare minor fortsatt kommer att påverka den mekaniserade striden i framtiden.  För att studera minors påverkan på den mekaniserade striden har den här studien använt Totalförsvarets forskningsinstituts simuleringsverktyg Suss-mek. Minvapnet finns sedan tidigare inte implementerat i programmet. Därför undersöks också vilka nyckelegenskaper som bör ingå i simulering med minor i strid.  Resultatet visar att effekten av framtidens minor på den mekaniserade striden kommer i grunden vara densamma som idag. Däremot kommer teknologin för framtidens minor göra att minan i sig kommer att bli effektivare med högre sannolikhet att nedkämpa motståndaren. Studien kommer också fram till flera relevanta nyckelegenskaper, till exempel front, djup, densitet och fasta beteenden vid sammanstötminering. Det är egenskaper som måste tas hänsyn till vid modellering av minor i ett simuleringsverktyg. / The development of the antitank mine has more or less stood still for the past 20 years. In the Defense Committee's final report Värnkraft, counter-mobility operations with landmines is described as one of the priority areas for the Swedish Armed Forces' combat engineer units. With this priority, there is a purpose to investigate how mines will continue to affect the mechanized battle in the future.  To study the impact of antitank mines on the mechanized battle, this study has used the Swedish Defense Research Agency's simulation tool Suss-mek. The mine weapon has not previously been implemented in the program. Therefore, it is also investigated which key characteristics that should be included in simulation with mines in battle.  The results show that the impact of future antitank- mines in mechanized battle will basically be the same as today. On the other hand, the technology of the future mines will make the mine itself more efficient with a higher probability to kill. The study also shows several relevant key characteristics for example: front, depth, density and fixed behaviours during entering minefield. They are characteristics that must be considered when modelling mines in a simulation tool.
105

Model Predictive Control as a Function for Trajectory Control during High Dynamic Vehicle Maneuvers considering Actuator Constraints

Bollineni, Tarun 04 May 2022 (has links)
Autonomous driving is a rapidly growing field and can bring significant transition in mobility and transportation. In order to cater a safe and reliable autonomous driving operation, all the systems concerning with perception, planning and control has to be highly efficient. MPC is a control technique used to control vehicle motion by controlling actuators based on vehicle model and its constraints. The uniqueness of MPC compared to other controllers is its ability to predict future states of the vehicle using the derived vehicle model. Due to the technological development & increase in computational capacity of processors and optimization algorithms MPC is adopted for real-time application in dynamic environments. This research focuses on using Model predictive Control (MPC) to control the trajectory of an autonomous vehicle controlling the vehicle actuators for high dynamic maneuvers. Vehicle Models considering kinematics and vehicle dynamics is developed. These models are used for MPC as prediction models and the performance of MPC is evaluated. MPC trajectory control is performed with the minimization of cost function and limiting constraints. MATLAB/Simulink is used for designing trajectory control system and interfaced with CarMaker for evaluating controller performance in a realistic simulation environment. Performance of MPC with kinematic and dynamic vehicle models for high dynamic maneuvers is evaluated with different speed profiles.
106

Der Sauerstoffverbrauch der Lunge (VO2pulm) bei Patienten mit Acute Lung Injury (ALI) und Acute Respiratory Distress Syndrome (ARDS) unter mechanischer Beatmung und PEEP-Variation, gemessen als VO2-Differenz zwischen indirekter Kalorimetrie und Berechnung über das inverse Fick´ sche Prinzip

Fritzsche, Katrin 27 November 2007 (has links)
Bei Patienten mit einem akuten Lungenversagen (ALI oder ARDS) ist der Sauerstoffverbrauch der Lunge (VO2pulm) durch pathophysiologische Prozesse insbesondere die Ausbildung von Atelektasen stark beeinträchtigt. Aufgrund der Annahme, dass eine Steigerung der Anzahl ventilierter Lungenareale zu einer Erhöhung des pulmonalen Sauerstoffverbrauchs führt, haben wir den Einfluss eines definierten Rekrutierungsmanövers (PEEP/PEAK + 10 cmH2O) auf den pulmonalen Sauerstoffverbrauch (VO2pulm), pulmonalen kapillären Blutfluss (PCBF), der den nicht geshunteten Anteil am HZV darstellt, und den transpulmonalen Shunt (Qs/Qt) untersucht. In der vorliegenden Studie wurde der VO2pulm als Differenz zwischen dem Sauerstoffverbrauch des gesamten Körpers, gemessen über die indirekte Kalorimetrie (VO2cal), und dem über das inverse Fick`sche Prinzip errechneten Sauerstoffverbrauch (VO2Fick) bestimmt. Im Rahmen einer klinisch-prospektiven Studie konnten nach Annahme des Studienprotokolls durch die zuständige Ethikkommission 13 beatmete Patienten, welche die Consensus-Kriterien eines ALI oder ARDS erfüllten, eingeschlossen werden. Nach Sicherstellung einer adäquaten Volumensituation und Messung der Ausgangsparameter wurde der PEEP um 10 cmH2O erhöht. Um ein stabiles Atemzugvolumen (VT 6-8 ml/kgKG) und damit gleichbleibende Bedingungen für die alveoläre Ventilation bis auf das von uns durchgeführte Rekrutierungsmanöver zu gewährleisten, wurde zeitgleich der Spitzendruck ebenfalls um 10 cmH2O erhöht. Nach 15 und 60 min wurden die Zieldeterminanten pulmonaler Sauerstoffverbrauch (VO2pulm), PCBF und transpulmonaler Shunt erneut bestimmt. Die Messung der indirekten Kalorimetrie (VO2cal) wurde mit dem Deltatrac TM, MBM 200® durchgeführt, VO2Fick über die Thermodilutionsmethode ermittelt, die partielle CO2-Rückatmungsmethode (David®) zur Bestimmung des PCBF genutzt und der transpulmonale Shunt (Qs/Qt) mittels der Formel nach BERGGREN berechnet. Die statistische Auswertung der Daten erfolgte mittels T-Tests für gepaarte Stichproben. Nach dem Manöver konnte eine signifikante Steigerung des PCBF von 4,44 ± 1,15 l/min auf 5,4 ± 1,68 l/min nach 15 min, respektive 5,12 ± 1,67 l/min nach 60 min nachgewiesen werden (p<0,025). Dieser Anstieg wurde von einer signifikanten Reduktion des transpulmonalen Shunts (Qs/Qt) von 0,24 ± 0,08 auf 0,16 ± 0,07 nach 15 min und 0,16 ± 0,07 nach 60 min begleitet (p<0,005). Diese Veränderungen der pulmonalen Hämodynamik gehen mit statistisch relevanten Verbesserungen der Oxygenierung sowie der Atemmechanik einher. Eine signifikante Steigerung des pulmonalen Sauerstoffverbrauchs konnte für die gesamte Studienpopulation nicht festgestellt werden. In dieser Untersuchung steigt der Sauerstoffverbrauch der Lunge deskriptiv von baseline 10,1 +/- 30,59 ml/min über 11,42 +/- 27,42 ml/min nach 15 min, respektive auf 28,69 +/- 56,75 ml/min nach 60 min an. Die signifikante Steigerung des pulmonal-kapillären Blutflusses und die konsekutive Reduktion des transpulmonalen Shunts schon 15 min nach dem Manöver impliziert einen Anstieg der an der alveolären Ventilation teilnehmenden alveolokapillären Einheiten, was einer Rekrutierung von vorher atelektatischen Lungenabschnitten entspricht. Insbesondere bei ARDS-Patienten und Respondern konnten Rekrutierungs-induzierte Veränderungen detektiert werden, wohingegen die Patienten mit ALI oder Nonresponder keinerlei statistische Unterschiede während der Intervention zeigten. Trotz stattgefundener Wiederbelüftung von Atelektasen konnte ein statistisch relevanter Unterschied bezüglich des pulmonalen Sauerstoffverbrauchs durch das Rekrutierungsmanöver für die gesamte Studienpopulation nicht festgestellt werden.
107

Simulation and Study of Gravity Assist Maneuvers / Simulering och studie av gravitationsassisterade manövrar

Santos, Ignacio January 2020 (has links)
This thesis takes a closer look at the complex maneuver known as gravity assist, a popular method of interplanetary travel. The maneuver is used to gain or lose momentum by flying by planets, which induces a speed and direction change. A simulation model is created using the General Mission Analysis Tool (GMAT), which is intended to be easily reproduced and altered to match any desired gravity assist maneuver. The validity of its results is analyzed, comparing them to available data from real missions. Some parameters, including speed and trajectory, are found to be extremely reliable. The model is then used as a tool to investigate the way that different parameters impact this complex environment, and the advantages of performing thrusting burns at different points during the maneuver are explored. According to theory, thrusting at the point of closest approach to the planet is thought to be the most efficient method for changing speed and direction of flight. However, the results from this study show that thrusting before this point can have some major advantages, depending on the desired outcome. The reason behind this is concluded to be the high sensitivity of the gravity assist maneuver to the altitude and location of the point of closest approach. / Detta examensarbete tittar närmare på den komplexa manöver inom banmekanik som kallas gravitationsassisterad manöver, vilken är vanligt förekommande vid interplanetära rymduppdrag. Manövern används för att öka eller minska farkostens rörelsemängd genom att flyga förbi nära planeter, vilket ger upphov till en förändring i fart och riktning. En simuleringsmodell är skapad i NASAs mjukvara GMAT med syftena att den ska vara reproducerbar samt möjlig att ändra för olika gravitationsassisterade manövrar. Resultaten från simuleringarna är validerade mot tillgängliga data från riktigt rymduppdrag. Vissa parametrar, som fart och position, har en väldigt bra överenstämmelse. Modellen används sedan för att noggrannare undersöka hur olika parametrar påverkar det komplexa beteendet vid en graviationsassisterad manöver, genom att specifikt titta på effekterna av en pålagd dragkraft från motorn under den gravitationsassisterade manövern. Teoretiskt fås mest effekt på fart och riktning om dragkraften från motorn läggs på vid punkten närmast planeten. Resultaten från denna studie visar att beroende på vilken parameter man vill ändra så kan man erhålla mer effekt genom att lägga på dragkraften innan den närmsta punkten. Förklaringen till detta är att den gravitationsassisterade manövern är väldigt icke-linjär, så en tidigare pålagd dragkraft kan kraftigt förändra farkostens bana nära planeten, så att farkosten t.ex. kommer närmare och då påverkas mer.
108

”Jag hade varit jobbig fast snäll” : En kombinerad vinjett- och intervjustudie om anhörigkonsulenters yrkesroll samt deras resonemang gällande våld i nära relation bland äldre / ”I would have been tough but kind” : A combined vignette and interview study about the professional role of relative consultants and their thoughts on domestic violence among the elderly.

Jutered, My, Kalenius, Hannah January 2022 (has links)
Syftet med denna kvalitativa studie var att få en fördjupad förståelse för anhörigkonsulenters arbete genom att undersöka hur de resonerade gällande situationer som innebär våld i nära relation bland äldre. Detta gjordes genom en kombinerad vinjett-och intervjustudie där sju anhörigkonsulenter fick ta del av två vinjetter med tillhörande följdfrågor. Empirin har analyserats med hjälp av tematisk analys. Resultatet visade tre övergripande teman som var: Våld bland äldre, Alliansen med den anhöriga och Yrkesrollen. Resultatet analyserades genom en teoretisk referensram som placerade anhörigkonsulenternas yrkesroll i en välfärdskontext samt med hjälp av teorin om arbetsalliansen. En slutsats var att arbetsalliansen framkom som ett viktigt redskap för anhörigkonsulenterna och de hade olika metoder för att skapa en allians. Samtidigt behövde de ständigt balansera mellan den anhörigas autonomi och säkerställa de äldres säkerhet. Utmärkande för deras yrkesroll var bland annat att de saknade myndighetsutövning vilket fick inverkan på deras handlingsutrymme. Resultatet diskuterades i förhållande till den alltmer restriktiva utvecklingen av äldreomsorgen och vilka konsekvenser detta har fått för anhöriga. / The purpose of this qualitative study was to gain an in-depth understanding of the work of relative consultants by examining how they reason about situations that involve domestic violence among the elderly. This was done through a combined vignette and interview study where seven relative consultants were given two vignettes with follow-up questions. The empirics have been analyzed using thematic analysis. The results showed three main themes which were: Violence among the elderly, The alliance with the relative and The professional role. The results were analyzed through a theoretical frame of reference that placed the professional role of the relative consultants in a welfare context and with the help of the theory of the working alliance. One conclusion was that the working alliance emerged as an important tool for the relative consultants and they had different methods for creating an alliance. At the same time, they needed to constantly balance between the relative's autonomy and ensure the safety of the elderly. Characteristic of their professional role were i.e. that they lacked the exercise of authority, which had an impact on their room for maneuver. In addition, the results were discussed in relation to the increasingly restrictive development of elderly care and what consequences this has had for relatives.
109

Hemodynamická optimalizace u jaterních resekcí / Hemodynamic optimalization in hepatic recection

Zatloukal, Jan January 2017 (has links)
Lowering of central venous pressure in hepatic surgery is nowadays widely recommended and used procedure. Low central venous pressure anesthesia is associated with decreased blood loss and improved clinical outcome. There are several approaches how to reach low central venous pressure. Till now none of them is recommended as superior in terms of patient safety and clinical outcome. Concurrently there is still debate if to use the low central venous pressure anesthesia principle or if it could be replaced with a principle of anesthesia with high stroke volume variation (or another dynamic preload parameter) with the use of a more sophisticated hemodynamic monitoring method. Results of our study didn't show any significant difference between two approaches used for reduction of central venous pressure, but suggest that the principle of low central venous pressure anesthesia could be possibly replaced by the principle of high stroke volume variation anesthesia which presumes the use of advanced hemodynamic monitoring. KEYWORDS Hepatic resection, central venous pressure, Pringle maneuver, hemodynamics, hemodynamic monitoring, fluid therapy, anesthesia
110

Simulation and Visualization of Environments with Multidimensional Time

Tychonievich, Luther A. 21 January 2008 (has links) (PDF)
This work introduces the notion of computational hypertime, or the simulation and visualization of hypothetical environments possessing multidimensional time. An overview of hypertime is provided,including an intuitive visualization paradigm and a discussion of the failure of common simulation techniques when extended to include multidimensional time. A condition for differential equations describing hypertime motion to be amenable to standard time-iterative simulation techniques is provided,but is not satisfied by any known model of physics. An alternate simulation algorithm involving iterative refinement of entire equations of motion is presented,with an example implementation to solve elastic collisions in hypertime. An artificial intelligence algorithm for navigating crowds in any arbitrary nD/mT environment is discussed,and an implementation is provided using collision cones and stochastic global optimization techniques. Possible models of hypertime energy and other open questions are discussed. Both algorithms are described and show favorable results, meeting all design criteria and running at interactive speeds on common desktop computer systems.

Page generated in 0.0488 seconds