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Návrh konstrukce rychlého elektromagnetického ventilu semiaktivního tlumiče / The design of fast electromagnetic valve for semiactive damperŽižlavský, Vít January 2021 (has links)
This diploma thesis’s focuses on the mechanical design of fast solenoid throttle valve for DCC semiactive damper. Current DCC dampers work with a time response of over 10 ms, which is not suitable for fast semiactive control of vehicle chassis. The time response needs to be shortened, to improve quality of regulation. The required time response is archived by new fast electromagnetic actuator for original CES valve. The actuator has been accelerated by reducing induction of eddy currents and by reducing weight of moving parts. New valve helped to reduce the time response of damper by 28 % to 8,1 ms. The results proved, that the time response is affected more by speed of the servo effect, which is closing main orifice, than by electromagnetic actuator. There is no more potential in accelerating CES valve by actuator.
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Stå i med stomi : Designprocessen för att representera något livs(kvalitet)viktigt / Stomach the stoma : The process of designing for quality of lifePost, Signe January 2019 (has links)
Syftet med denna rapport var att ta fram ett namn och logotyp till PysUts nya stomiventil som speglar produktvarumärkets värdeord. Ventilen är en marknadsbrytande produkt, som i början av arbetet inte hade någon form av grafiskt material eller ett väl fungerande namn. Till grund för arbetet ligger ett antal källor som berör värdeord, och vad en logotyp är, som bryts ner i delarna färg, form och typografi. Innan arbetet påbörjades gjordes en förstudie där företagets konkurrenter undersöktes, något som lade grund för det vidare designarbetet. Eftersom varumärket inte hade några värdeord vid arbetets start var detta det första som gjordes. Detta gjordes genom en workshop med företagsägaren. Utifrån värdeorden togs två namn fram där tre logotyper skapades till vardera. De sex logotyperna värderades sedan med hjälp av en kvalitativ och kvantitativ enkät, där både stomibärare och ickestomibärare fick svara. Dock skiljdes de två gruppernas svar åt för att kunna genomföra analysen. Under analysen reviderades värdeorden utifrån respondenternas svar, och designen av logotypen värderades därefter. / The purpose of this report was to produce a name and logo for PysUt's new stoma vent that reflects the product brand's key words. The vent is a market-breaking product, which at the beginning of the work had no form of graphic material or a well-functioning name. The basis for the work is several sources that concern key words and what a logo is, which is brokendown into the parts color, shape and typography. Before the work was started, a preliminary study was conducted where the company's competitors were investigated, which laid the foundation for the further design work. Since the brand had no key words at the start of the work, those were the first to be made. This was done through a workshop with the business owner. Based on the key words, two names were picked out where three logos were created for each. The six logos were then evaluated with the help of a qualitative and quantitative questionnaire, where both stoma carriers and non-stoma carriers got to answer. However, the two groups' responses were separated to be able to carry out the analysis. During the analysis, the key words were revised based on the respondents' answers, and the design of the logo was then evaluated.
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Modelování vodního zástřikového systému parního ventilu / Modelling of water distributor in a steam conditioning valvePolášek, Radek January 2018 (has links)
The purpose of the thesis is to create a model for an analysis of a steam conditioning valve whose function is to reduce the temperature of the steam using a spray water system. First of all, simulation of the fluid flow and heat transfer is done using CFD analysis. Then the results are used for thermal stress calculation.
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Řízení činnosti vývěvy dojicího strojeKudělka, Jan January 2016 (has links)
Dissertation is concerned with the activity of the pump milking machine in order to save energy while maintaining the stability of the vacuum. The searching describes the operation of milking machine with regulation in vakuum milking systém. The literature review characterizes the basic functional components of milking equipment, their characteristics and technical specifications. The purpose of practical part is to design, create and describe alternatives for controlling the operation of milking machine´s pump via the inverter. Other importem task is to recommend a methodology to interpret the measurement of vacuum and consumption of electricity so the sets parameters can be compared. Dissertation also vertifies if the involvement of the drive systém can not adversely affect the operation of asynchronous electric motor.
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Hemodynamic Follow-Up after Valve-in-Valve TAVR for Failed Aortic BioprosthesisWilbring, Manuel, Kappert, Utz, Haussig, Stephan, Winata, Johan, Matschke, Klaus, Mangner, Norman, Arzt, Sebastian, Alexiou, Konstantin 01 March 2024 (has links)
Background
“valve-in-valve” TAVR (VIV-TAVR) is established and provides good initial clinical and hemodynamic outcomes. Lacking long-term durability data baffle the expand to lower risk patients. For those purposes, the present study adds a hemodynamic 3-years follow-up.
Methods
A total of 77 patients underwent VIV-TAVR for failing aortic bioprosthesis during a 7-years period. Predominant mode of failure was stenosis in 87.0%. Patients had a mean age of 79.4 ± 5.8 years and a logistic EuroSCORE of 30.8 ± 15.7%. The Society of Thoracic Surgeons-PROM averaged 5.79 ± 2.63%. Clinical results and hemodynamic outcomes are reported for 30-days, 1-, 2-, and 3-years. Completeness of follow-up was 100% with 44 patients at risk after 3-years. Follow-up ranged up to 7.1 years.
Results
Majority of the surgical valves were stented (94.8%) with a mean labeled size of 23.1 ± 2.3 mm and true-ID of 20.4 ± 2.6 mm. A true-ID ≤21 mm had 58.4% of the patients. Self-expanding valves were implanted in 68.8% (mean labeled size 24.1 ± 1.8 mm) and balloon-expanded in 31.2% (mean size 24.1 ± 1.8 mm). No patient died intraoperatively. Hospital mortality was 1.3% and three-years survival 57.1%. All patients experienced an initial significant dPmean-reduction to 16.8 ± 7.1 mmHg. After 3-years mean dPmean raised to 26.0 ± 12.2 mmHg. This observation was independent from true-ID or type of transcatheter aortic valve replacement (TAVR)-prosthesis. Patients with a true-ID ≤21 mm had a higher initial (18.3 ± 5.3 vs. 14.9 ± 7.1 mmHg; p = .005) and dPmean after 1-year (29.2 ± 8.2 vs. 13.0 ± 6.7 mmHg; p = .004). There were no significant differences in survival.
Conclusions
VIV-TAVR is safe and effective in the early period. In surgical valves with a true-ID ≤21 mm inferior hemodynamic and survival outcomes must be expected. Nonetheless, also patients with larger true-IDs showed steadily increasing transvalvular gradients. This raises concern about durability.
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Tetra-Responsive Grafted Hydrogels for Flow Control in MicrofluidicsGräfe, David 10 March 2017 (has links) (PDF)
Microfluidics covers the science of manipulating small quantities of fluids using microscale devices with great potential in analysis, multiplexing, automation and high-throughput screening. Compared to conventional systems, microfluidics benefits from miniaturization resulting in shortened time of experiments, decreased sample and reagent consumptions as well as reduced overall costs. For microfluidic devices where further weight and cost reduction is additionally required, stimuli-responsive hydrogels are particularly interesting materials since they can convert an environmental stimulus directly to mechanical work without any extra power source. Hydrogels are used as chemostats, micropumps, and chemo-mechanical valves in microfluidics.
Existing studies about hydrogels for flow control reported on hydrogels responsive to only one stimulus, including temperature, pH value, and solvent. Combining temperature and pH stimuli within one material is an interesting approach, which allows internal as well as external flow control and broadens potential applications. Among the variety of temperature- and pH-responsive monomers, N-isopropylacrylamide (NiPAAm) and acrylic acid (AA) are considered as ideal building blocks to obtain a hydrogel with pronounced stimuli response. There are different architectures for realizing a temperature- and pH-responsive hydrogel with NiPAAm and AA (e.g. copolymer gels, interpenetrating polymer networks (IPNs), semi-IPNs, or graft copolymer gels). Each approach has its inherent benefits and disadvantages. Grafted hydrogels with a temperature-responsive backbone and pH-responsive graft chains are a promising architecture overcoming drawbacks of copolymer gels (loss of thermoresponsive behavior due to the comonomer), interpenetrating polymer networks (IPNs, difficult fabrication of structured particles via soft lithography), and semi-IPNs (leakage of penetrating polymer). However, studies about multi-responsive grafted hydrogels for flow control in microfluidics are comparatively rare and further research is needed to emphasize their real potential.
For this reason, the overall aim of this work was the synthesis of temperature- and pH-responsive grafted hydrogels based on NiPAAm and AA for flow control in microfluidics. This required the synthesis of a pH-responsive macromonomer by RAFT polymerization. As a suitable chain transfer agent with a carboxylic acid group for an end-group functionalization, 2-(dodecyl-thiocarbonothioylthio)-2-methylpropionic (DTP) acid was employed. The approach towards the synthesis of the pH-responsive macromonomer based on two key steps: (i) attaching a functional group, which retains during RAFT polymerization, and (ii) conducting the RAFT polymerization to synthesize the pH-responsive macromonomer. In total, four functionalizations for the macromonomer were investigated, including allyl, unconjugated vinyl, acrylamide, and styrene. End-group analysis and solubility tests revealed that macromonomers with a styrene functionalization are suitable for the synthesis of graft copolymer gels.
A series of grafted net-PNiPAAm-g-PAA-styrene hydrogels with a PNiPAAm backbone and PAA-styrene graft chains (Mn = 4200 g/mol, Mw/Mn = 1.6) were prepared and characterized. The main goal was to identify suitable stimuli for an application as a chemo-mechanical valve and to show reversibility of the swelling and shrinking process. Importantly, the temperature sensitivity should be retained, while a pH response needs to be introduced. Equilibrium swelling studies quantified with the response ratio revealed that a grafting density of PAA-styrene between 0.25 and 1 mol-% provides a suitable response towards temperature, pH, salt, and solvent. Furthermore, the swelling and shrinking process is highly reproducible over four consecutive cycles for all four stimuli. In order to evaluate the swelling kinetics of grafted net-PNiPAAm-g-PAA-styrene hydrogels, the collective diffusion model extended by a volume specific surface was applied. The determined cooperative diffusion coefficients of net-PNiPAAm-g-PAA-styrene indicated faster response time with increasing PAA-styrene content. Remarkably, net-PNiPAAm-g-PAA-styrene containing 1 mol-% PAA-styrene exhibited an accelerated swelling rate by a factor of 9 compared to pure net-PNiPAAm. Rheological analysis of net-PNiPAAm-g-PAA-styrene showed that an increasing graft density leads to decreasing mechanical stability. The photopolymerization experiments showed that the gelation time linearly increases with the grafting density.
Grafted net-PNiPAAm-g-PAA-styrene hydrogels were tested in two fluidic setups for flow control. A straightforward fluidic platform was developed consisting of a fluid reservoir, an inlet channel, an actuator chamber and an outlet channel. The actuator chamber was filled with crushed hydrogel particles. Accordingly, the fluid flow was directed by the active resistance of the hydrogel particles in the actuator chamber (i.e. swelling degree) and allowed flow control by the local environmental conditions. Flow rate studies showed that the fluid flow throttles when the inlet channel was provided with a solution in which the hydrogel swells (pH 9 buffer solution at room temperature). In contrast, the hydrogel-based valve opens immediately when a solution was used in which the hydrogel collapses. The advantageous properties of net-PNiPAAm-g-PAA-styrene were highlighted by using pH, salt and solvent stimulus in one experiment. Remarkably, the opening and closing function was reversible over six consecutive cycles.
As part of a collaboration project with the chair of polymeric microsystems within the Cluster of Excellence Center for Advancing Electronics Dresden (A. Richter and P. Frank), membrane assures hydraulic coupling in a chemo-fluidic membrane transistor (CFMT) and grafted net-PNiPAAm-g-PAA-styrene hydrogels were combined to emphasize the potential of both systems. Flow rate studies showed that 4 different stimuli can be used to control the opening and closing state of the CFMT. Multiple opening and closing cycles revealed no considerable changes in the valve function emphasizing a high potential for an application in microfluidics.
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Ventil na principu vířivé turbiny / Valve Exploiting Principle of the Side-Channel TurbineJandourek, Pavel January 2017 (has links)
The presented work deals with basic characteristics of the side-channel machines. The intention is to replace the pressure reducing valve by low-specific speed side-channel turbine. Thereby creating a kind of turbine valve using energy, which would otherwise be dissipated in the valve. Pressure reducing valves are the source of large hydraulic losses and their replacement is possible, because the same resistance characteristics side-channel turbine and a pressure reducing valve.
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Reducerande ventiler i fjärrvärmenätet : Reducerande ventilers påverkan på framtidens fjärrvärmenätÖhman, Felix January 2023 (has links)
Fjärrvärmen utgör omkring hälften av all uppvärmning som sker i Sverige idag och har utöver det en viktig roll då den tar vara på mycket energi som annars hade gått till spillo. Att kunna vara ekonomiskt konkurrenskraftig gentemot andra uppvärmningsalternativ är en viktig del för fjärrvärmens fortsatta utveckling. Det finns flera alternativ och möjligheter att göra detta, ett av dem är att hålla nere driftkostnaderna. Det kan bland annat göras genom att minska tryckfallen i näten, som även kan ge en ökad expansionsmöjlighet. Idag används främst avstängningsventiler med reducerande genomlopp i näten, främst på grund av den billigare investeringen. Trots detta saknas en kunskap om hur dessa ventiler påverkar näten sett till tryckfall, drift- och investeringskostnader jämfört med ventiler med fullt genomlopp. För att undersöka detta har två metoder använts för att komplettera varandra och öka förståelsen för ventilerna. Den första metoden beräknade det generella fallet teoretiskt för att se vid vilka flöden som ventiler med fullt genomlopp är mer gynnsamma. Den andra metoden beräknade ett specifikt fall med simuleringar i ett verkligt nät med de olika ventilerna och beräkna vilken som är den mest ekonomiskt gynnsamma. Resultaten av det generella fallet visar att ventiler med fullt genomlopp blir mer gynnsamma när flödeshastigheten överstiger omkring 1 m/s, oavsett dimension, beräknat på under 30 år med ett elpris på 1,50 kr/kWh. Vid dimensionering av nät är det vanligt att använda 1,5 - 2,0 m/s, detta utgör ofta en liten del av nätets drifttid och är ofta lägre. Beräkning av det specifika fallet visade att ventiler med reducerande genomlopp är det ekonomiska alternativet då återbetalningstiden för ventiler med fullt genomlopp var över 600 år vid 1,50 kr/kWh. Utifrån detta kan slutsatsen dras att ventiler med fullt genomlopp inte bör ersätta reducerande genomlopp, utan att det i stället handlar om att identifiera de delar i nätet som utgör, eller kan komma att utgöra, en strypning eller förträngning i nätet där höga flödeshastigheter kan förekomma och möjligtvis byta till fullt genomlopp. / District heating makes up about half of all heating that takes place in Sweden today and, in addition to that, has an important role as it makes use of a lot of energy that would otherwise have been wasted. Being able to be economically competitive against other heating alternatives is an important part of the continued development of district heating. There are several options to do this, one of which is to keep operating costs down. This can be done by reducing the pressure drops in the networks, which can also provide an increased possibility of expansion. Today, shut-off valves with reducing throughput are mainly used in networks, often because of the cheaper investment. Despite this, there is a lack of knowledge about how these valves affect the networks, which is attributed to pressure drop, operating and investment costs compared to valves with full flow. To investigate this, two methods have been used to complement each other and increase the understanding of the valves. In the first method, the general case is calculated theoretically to see at which flows valves with full flow are advantageous. The second method calculates a specific case with simulations in a real network with the different valves and calculates which one is the most economically advantageous. The results of the general case show that valves with full flow become more advantageous when the flow rate exceeds about 1 m/s, regardless of dimension, calculated over 30 years with an electricity price of SEK 1.50 /kWh. When dimensioning networks, 1.5 - 2.0 m/s is a common value, this often constitutes a small part of the network's operating time and is often lower. Calculation of the specific case showed that valves with reducing throughput are the economic alternative as the payback period for valves with full throughput was over 600 years at SEK 1.50/kWh. Based on this, the conclusion can be drawn that valves with full throughput should not replace reducing throughput, but that it is instead a question of identifying the parts of the network that constitute a throttling or constriction in the network where high flow rates can occur and possibly switch to valves with full throughput.
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Servopohon rychlouzávěrného ventilu parní turbiny / Actuator of fast closing valve steam turbineKirst, Pavel January 2016 (has links)
Aim of this thesis is construction design of hydraulic control speed close valve steam turbine. Thesis will be contain low pressure and high pressure variant. In a theoretical part will be describe types of steam turbines, speed close valves, basic terminology and description of control elements. There will be also designed hydraulic circuits and performed calculations of individual elements. Finally will be created construction design of low pressure variant.
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Modellering och reglering av mjölkningsrobot / Modelling and controlling of a milking machineKarlsson, Fredrik, Kastman, Mattias January 2002 (has links)
In this master thesis a robot arm belonging to an automatic milking machine from DeLaval is investigated. The robot arm is controlled by a pneumatic cylinder and a valve. The goal of the master thesis is to investigate instability problems and to find out if it is possible to solve them by using gain scheduling. Gain scheduling is a type of controller where the parameters of the controller are changed during operation, for example depending on the working point. First a nonlinear mathematical model of the system was made. Then a test rig was built with a robot arm and sensors, identical to the ones mounted on the real machine from DeLaval. The different parameters of the nonlinear model were then tuned and validated against data from the test rig to make sure that the model is correct. After that the nonlinear model was linearized for a closer analysis of the parameters that seemed to have an apparent effect on the system behaviour. The result of the analysis showed that the probable cause of instability is a decrease of the viscous friction, which gives worse damping characteristics. It was more suitable to base the controller parameters on the valve opening instead of the working point for the robot arm, since the gain in the valve increases with increasing valve opening. To avoid deterioration in phase margin because of the increased gain, the controller is adjusted so that the total gain is the same regardless of valve opening. The result is a system with larger bandwidth, less sensitive to changes in the viscous friction.
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