Дисертації з теми "Vacuum Measurement"
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1
Hoagland, David Wayne. "Continuous Permeability Measurement During Unidirectional Vacuum Infusion Processing." BYU ScholarsArchive, 2017. https://scholarsarchive.byu.edu/etd/6457.
Повний текст джерелаАнотація:
Composite materials have traditionally been used in high-end aerospace parts and low-end consumer parts. The reason for this separation in markets is the wide gap in technology between pre-preg materials processed in an autoclave and chop strand fiberglass blown into an open mold. Liquid composite molding has emerged as a bridge between inexpensive tooling and large, technical parts. Processes such as vacuum infusion have made it possible to utilize complex layups of reinforcement materials in an open mold style set-up, creating optimal conditions for composites to penetrate many new markets with rapid innovation. Flow simulation for liquid composite molding is often performed to assist in process optimization, and requires the permeability of the reinforcement to be characterized. For infusion under a flexible membrane, such as vacuum infusion, or for simulation of a part with non-uniform thickness, one must test the permeability at various levels of compaction. This process is time consuming and often relies on interpolation or extrapolation around a few experimental permeability measurements. To accelerate the process of permeability characterization, a small number of methodologies have been previously presented in the literature, in which the permeability may be tested at multiple fiber volume contents in a single test. Some of the methods even measure the permeability over a continuous range of thicknesses, thus requiring no later interpolation of permeability values. A novel method is presented here for the rapid measurement of permeability over a continuous range of fiber volume content, in a single unidirectional vacuum infusion flow experiment. The thickness gradient across the vacuum bag, as well as the fluid pressure at several locations in the mold, were concurrently measured to calculate the fabric compressibility. An analytical flow model, which accounts for the compressibility, is then used by iterating the fitting constant in a permeability model until the predicted flow front progression matches empirical measurement. The method is demonstrated here for two reinforcement materials: 1) a fiberglass unbalanced weave and 2) a carbon bi-ax non-crimped fabric. The standard deviation of calculated permeabilities across the multiple infusion experiments for each material and flow orientation ranged from 12.8% to 29.7%. Validation of these results was performed by comparing the resulting permeability with multiple non-continuous permeability measurement methods.
2
Konno, T., L. Ren, G. Piao, García J. M. Juárez, F. M. Suárez, S. J. Jimenez-Sandoval, T. Wakahara, K. Miyazawa, and E. M. Ferreira. "Raman Spectroscopic Measurement of a Vacuum-Deposited C60 Thin Film." Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/42804.
Повний текст джерелаАнотація:
Measurement of Raman shifts of a C60 thin film and the evaluation of their uncertainties were conducted. A C60 thin film with a thickness of about 1.2 μm was fabricated on a SiO2 substrate by vacuum deposition. Raman spectra of the C60 thin film were obtained using the laser beam power density of 5.7 103 mW mm-2. The measured Raman shifts were corrected according to the calibration curve that was prepared using sulfur and naphthalene as the reference samples. Standard uncertainties were calculated and combined in order to determine the combined uncertainty and the expanded uncertainty. It was found that the increase of measurement
time and measurement points for the calibration curve leads to the higher reliability.
3
Al-Rawi, S. A. N. "Silicon sublimation at ultra high vacuum with microprocessor monitoring and measurements." Thesis, University of Kent, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382189.
Повний текст джерела
4
Taghvaei, Mohammad. "Interface circuitry design for a MEMS resonator-based vacuum measurement system." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106505.
Повний текст джерелаАнотація:
This work focuses on the interface circuitry design for MEMS resonator-based vacuum sensors. Two new measurement system topologies are proposed. The required specifications and the design of the comprising blocks for each topology are studied in detail. Next, the correct functionality and performance specifications of both architectures – designed in an IBM 0.13 μm CMOS technology – are presented through a combination of post-layout simulations and measurement results. Furthermore, the advantages and disadvantages of each design are examined in detail, followed by a comparison to similar commercial systems currently available on the market.Finally, setting the ultimate goal of building a low-power, monolithic, integrated MEMS-based temperature-compensated vacuum measurement system, areas with potential for future improvement, and expansion are discussed.Ce travail présente la conception de circuits d'interface, pour la mesure de pression sous vide à l'aide de résonateurs MEMS. Deux nouvelles structures de systèmes de mesure sont proposées. Les spécifications requises, ainsi que la conception des blocs composants pour chaque structure, sont étudiées en détail. Par la suite, l'opération adéquate et les spécifications de performance pour les deux architectures - conçues par la technologie CMOS de IBM à 0.13 μm - sont présentées par une combinaison de simulations post-layout et de résultats mesurés. De plus, les avantages et inconvénients de chaque structure sont évalués en détail, suivis d'une comparaison avec des systèmes commerciaux similaires présentement disponibles sur le marché. Finalement, pour s'approcher du but ultime de construire le meilleur système intégré et monolithique de mesure de pression sous vide, à faible consommation de puissance et avec compensation pour les variations thermiques, les possibilités d'améliorations futures et d'extension sont discutées.
5
Talib, Zeeshan. "Investigation of Fast High Voltage PDC Measurement based on a Vacuum Reed-switch." Thesis, KTH, Elektroteknisk teori och konstruktion, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-91924.
Повний текст джерелаАнотація:
The diagnostic technique, polarization and depolarization current (PDC) is useful for insulation testing. It requires applying a DC step voltage to the test sample and measuring the current. To measure fast PDC phenomena a fast step is needed. One way of applying a fast high voltage step is to use power electronic switches. Series connection can be used to increase the voltage limit, but this result in unequal voltage sharing unless equipped with voltage balancing. In this work a high voltage vacuum reed switch is investigated as a simple and low-cost alternative to power electronic switches, handling up to 10 kV with a single device. The switch turn on and off behavior was studied. It was found that the initial turn-on is good, in the range of nanoseconds, but there is a problem with the vacuum recovering its insulating properties at low currents before the contacts fully close. The required output voltage level is therefore obtained only after a further settling time that increases with increased input voltage and is much longer than the initial breakdown, e.g. 20 µs for the case of 4.5 kV input voltage. Other limitations of the fast high voltage PDC were also studied. The output voltage was measured across the test sample without adding an intentional resistor in the circuit. There were large oscillations for 1 µs but these oscillations are damped due to inherent resistance of the connecting leads, series resistance of the capacitors and resistance of the reed switch. A comparison is made between the measured and the simulated results using MATLAB to see the effect of parasitic inductance. A damping resistor was added in the circuit and the output results were again compared. With the addition of the damping resistor, the number of oscillations were reduced and their time scale was limited to 0.1 µs . An analysis is made at the end which describes the limitation occurring in determining the high frequency component of PDC. The current during the step is many orders of magnitude higher than the polarization current even at 1 µs , so measurement of the current and protection of the apparatus is not trivial.
6
Chew, Andrew David. "A rotating disc gauge for absolute total pressure measurement in a high vacuum." Thesis, University of York, 1993. http://etheses.whiterose.ac.uk/10874/.
Повний текст джерела
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Lun, Jonathan. "Development of a vacuum arc thruster for nanosatellite propulsion." Thesis, Stellenbosch : University of Stellenbosch, 2008. http://hdl.handle.net/10019.1/1527.
Повний текст джерелаАнотація:
Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2009.This thesis describes the development of a vacuum arc thruster (VAT) to be used as a potential low mass (< 500 g), low power (< 5–10W) propulsion system for nanosatellites. The thruster uses a high voltage capacitive circuit to initiate and power the arc process with a 400 ns high current (150–800A) pulse. A one-dimensional steady state analyticalmodel describing the cathode region of the vacuum arc was developed. The model made use of mass and energy balances at the sheath region and cathode surface respectively to predict key quantities such as thrust, ion velocity, ion-to-arc current ratio and erosion rate. Predicted results were shown to be within the limits of reported literature (∼63 μN/A, 26.12 km/s, 0.077 and 110 μg/C respectively). A sensitivity analysis of the analytical model found that a high electric field in the cathode region impedes and decelerates ion flow, which is used for thrust. This was confirmed experimentally for thrust values at arc voltages greater than 2000 V. Both direct and indirect means of measuring thrust were achieved by using a deflecting cantilever beam and an ion collector system, respectively. The transient response of the cantilever beam to impulsive thrust was analytically modeled, whilst the ion current was found by measuring the current induced on a plate subject to ion bombardment. Knowledge of the ion current density distribution was successfully used to approximate the effective normal thrust vector. Direct and indirect thrust levels were roughly 140 and 82 μN/A of average arc current, respectively. Measured thrust was found to be higher than predicted thrust due to thrust contributions fromthe ablation of Teflon insulation. The discrepancy is also due to the uncertainty in quantifying free parameters in the analytical model such as the fraction of generated ions flowing away from the cathode region. The thrust-topower ratio, specific impulse and efficiency of the vacuum arc thruster at an average arc current of 200 A was measured to be 0.6 μN/W, 160 s and 0.05 %, respectively. A thruster performance analysis and specification showed that the VAT is capable of achieving specific orbital and slew manoeuvres within a constant 5–10 W average power. It was concluded that thruster performance could be improved by using a two-stage arc circuit consisting of a high voltage, low current, short pulse trigger and a low voltage, high current, long pulse driver.
8
Nagai, Hisao, Mineo Hiramatsu, Masaru Hori, and Toshio Goto. "Measurement of oxygen atom density employing vacuum ultraviolet absorption spectroscopy with microdischarge hollow cathode lamp." American Institute of Physics, 2003. http://hdl.handle.net/2237/7098.
Повний текст джерела
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Hannibal, Paul. "Compressibility Measurement and Modeling to Optimize Flow Simulation of Vacuum Infusion Processing for Composite Materials." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/4433.
Повний текст джерелаАнотація:
Out-of-autoclave manufacturing processes for composite materials are increasing in importance for aerospace and automotive industries. Vacuum Infusion processes are leading the push to move out of the autoclave. An understanding of the various process parameters associated with resin infusion is necessary to produce quality product. Variance in compaction, resin, and vacuum pressures are studied, concentrating on developing a compaction pressure profile as it relates to fiber volume fraction. The purpose of this research is twofold: (1) to show and quantify the existence of a resin pressure gradient in compression testing using rigid tooling, and (2) to use measured test data to validate and improve resin flow simulation models. One-dimensional compression tests revealed a pressure gradient across the diameter of the compression tool. The pressure gradient follows trends consistent with Darcy's Law. Compression tests revealed fabric hysteresis during compaction as shown in previous studies. Fiber compaction pressure was found to not be directly equal to compressive forces of the Instron when resin is present in the system. The relationship between Instron, resin and compaction pressures is defined. The compression study was used to validate previously developed flow simulation models. Resin pressures are critical to developing an accurate two-dimensional radial flow simulation for low permeability fabrics. It is feasible to determine final fiber volume fraction at a given compaction pressure.
10
Chapanian, Rafi. "Study of accumulation of gases in vacuum systems: Measurement of gas transport properties of polymeric films." Thesis, University of Ottawa (Canada), 2004. http://hdl.handle.net/10393/26598.
Повний текст джерелаАнотація:
In this thesis we have proven that the resistance to accumulation of gases in vacuum tubes is not always negligible. The process of accumulation was described using the Fick's second law of diffusion. The diffusion coefficient was assumed constant and evaluated, depending on pressure, considering Knudsen diffusion, molecular diffusion, or a combination of them. Experimental system with tubes of different lengths and diameters was built and equipped with two high sensitivity pressure transducers to measure the dynamic pressure difference along the system during gas flow experiments. Two cases were considered. First, the governing partial differential equation was solved analytically assuming a constant flow of gas into the system. Experimentally, a low-flow mass flow controller provided the constant flow of gas into the system. In the second case, the governing partial differential equation was solved numerically assuming a time-dependent flow of gas given by the Barrer equation. (Abstract shortened by UMI.)
11
Tina, Monteiro Shelsea. "Real Time Measurement of Dirt Pick-up by a Robotic Vacuum Cleaner using Light Sensing Technology." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-254349.
Повний текст джерелаАнотація:
Domestic chores are one of the most tedious and time consuming tasks in a person’s life. A lot of time can be saved and put to better use if these tasks can be automated. One such chore is the routine task of vacuuming the house every day. Robotic vacuum cleaners that clean the house are thus one of the most widely used domestic robots. These robots have the ability to clean the entire house almost autonomously with little or no human intervention. However, most of these robots do not have a system to report the real-time pick up of dirt which can be useful to the user in knowing which parts of his house are dirty and maybe investigate the reason behind it. This information can be useful to the robot as well in determining efficient cleaning patterns based on the dirt localization in the house. In this thesis a prototype was developed to measure the real-time pick-up of dirt by a robotic vacuum cleaner. It uses light sensing technology to measure the amount of dirt picked up and can thus be used to glean which parts of the house are dirtier than the others. The signals can also potentially be used to understand the size of the dirt picked up by the robotic vacuum cleaner. Research was done to investigate the different sensing technologies that can be used and to select the appropriate one. The system was tested and conclusions were made regarding its performance. Additional functions that can be implemented and improvements that can be made have also been suggested as future work.Att städa hemmet är en av de mest tråkiga och tidskrävande uppgifterna i en persons liv. Mycket tid kan sparas och användas bättre om dessa uppgifter kan automatiseras. Robotdammsugare som städar golvet i hemmet är en av de mest använda inhemska robotarna, då dessa robotar har möjlighet att rengöra hela huset nästan autonomt med liten eller ingen mänsklig intervention. De flesta av dessa robotar har dock inte ett system för att rapportera realtidsupphämtning av smuts som kan vara användbart, då användaren kan få reda på vilka delar av huset som är smutsiga och då ha möjlighet att undersöka orsaken bakom. Denna information kan också vara användbart för roboten för att bestämma effektiva rengöringsmönster baserat på lokalisering av smuts i huset. I denna avhandling utvecklades en prototyp för att mäta upptagning av smuts i realtid av en robotdammsugare. Den använder IR-teknik för att mäta mängden smuts som hämtas upp och kan därmed använda informationen för att avgöra vilka delar av huset som är smutsigare än andra. Signalerna kan också potentiellt användas för att förstå storleken på smuts som tas upp. Forskning av olika tekniker utfördes för att kunna välja den mest lämpliga. Systemet testades därefter och slutsatser gjordes avseende dess prestanda. Ytterligare utredningar och förbättringar som kan genomföras har också föreslagits som framtida arbete.
12
Karami, Peyman. "Robust and Durable Vacuum Insulation Technology for Buildings." Doctoral thesis, KTH, Byggnadsteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176494.
Повний текст джерелаАнотація:
Today’s buildings are responsible for 40% of the world’s energy use and also a substantial share of the Global Warming Potential (GWP). In Sweden, about 21% of the energy use can be related to the heat losses through the climatic envelope. The “Million Program” (Swedish: Miljonprogrammet) is a common name for about one million housing units, erected between 1965 and 1974 and many of these buildings suffer from poor energy performance. An important aim of this study was to access the possibilities of using Vacuum Insulation Panels (VIPs) in buildings with emphasis on the use of VIPs for improving the thermal efficiency of the “Million Program” buildings. The VIPs have a thermal resistance of about 8-10 times better than conventional insulations and offer unique opportunities to reduce the thickness of the thermal insulation. This thesis is divided into three main subjects. The first subject aims to investigate new alternative VIP cores that may reduce the market price of VIPs. Three newly developed nanoporous silica were tested using different steady-state and transient methods. A new self-designed device, connected to a Transient Plane Source (TPS) instrument was used to determine the thermal conductivity of granular powders at different gaseous pressure combined with different mechanical loads. The conclusion was that the TPS technique is less suitable for conducting thermal conductivity measurements on low-density nanoporous silica powders. However, deviations in the results are minimal for densities above a limit at which the pure conduction becomes dominant compared to heat transfer by radiation. The second subject of this work was to propose a new and robust VIP mounting system, with minimized thermal bridges, for improving the thermal efficiency of the “Million Program” buildings. On the basis of the parametric analysis and dynamic simulations, a new VIP mounting system was proposed and evaluated through full scale measurements in a climatic chamber. The in situ measurements showed that the suggested new VIP technical solution, consisting of 20mm thick VIPs, can improve the thermal transmittance of the wall, up to a level of 56%. An improved thermal transmittance of the wall at centre-of-panel coordinate of 0.118 to 0.132 W m-2K-1 and a measured centre-of-panel thermal conductivity (λcentre-of-panel) of 7 mW m-1K-1 were reached. Furthermore, this thesis includes a new approach to measure the thermal bridge impacts due to the VIP joints and laminates, through conducting infrared thermography investigations. An effective thermal conductivity of 10.9 mW m-1K-1 was measured. The higher measured centre-of-panel and effective thermal conductivities than the published centre-of-panel thermal conductivity of 4.2 mW m-1K-1 from the VIP manufacturer, suggest that the real thermal performance of VIPs, when are mounted in construction, is comparatively worse than of the measured performance in the laboratory. An effective thermal conductivity of 10.9 mW m-1K-1 will, however, provide an excellent thermal performance to the construction. The third subject of this thesis aims to assess the environmental impacts of production and operation of VIP-insulated buildings, since there is a lack of life cycle analysis of whole buildings with vacuum panels. It was concluded that VIPs have a greater environmental impact than conventional insulation, in all categories except Ozone Depilation Potential. The VIPs have a measurable influence on the total Global Warming Potential and Primary Energy use of the buildings when both production and operation are taken into account. However, the environmental effect of using VIPs is positive when compared to the GWP of a standard building (a reduction of 6%) while the PE is increased by 20%. It was concluded that further promotion of VIPs will benefit from reduced energy use or alternative energy sources in the production of VIP cores while the use of alternative cores and recycling of VIP cores may also help reduce the environmental impact. Also, a sensitivity analysis of this study showed that the choice of VIPs has a significant effect on the environmental impacts, allowing for a reduction of the total PE of a building by 12% and the GWP can be reduced as much as 11% when considering both production and operation of 50 yes. Finally, it’s possible to conclude that the VIPs are very competitive alternative for insulating buildings from the Swedish “Million Program”. Nevertheless, further investigations require for minimizing the measurable environmental impacts that acquired in this LCA study for the VIP-insulated buildings.Dagens byggnader ansvarar för omkring 40% av världens energianvändning och står också för en väsentlig del av utsläppen av växthusgaser. I Sverige kan ca 21 % av energianvändningen relateras till förluster genom klimatskalet. Miljonprogrammet är ett namn för omkring en miljon bostäder som byggdes mellan 1965 och 1974, och många av dessa byggnader har en dålig energiprestanda efter dagens mått. Huvudsyftet med denna studie har varit att utforska möjligheterna att använda vakuumisoleringspaneler (VIP:ar) i byggnader med viss fokus på tillämpning i Miljonprogrammets byggnader. Med en värmeledningsförmåga som är ca 8 - 10 gånger bättre än för traditionell isolering erbjuder VIP:arna unika möjligheter till förbättrad termisk prestanda med minimal isolerings tjocklek. Denna avhandling hade tre huvudsyften. Det första var att undersöka nya alternativ för kärnmaterial som bland annat kan reducera kostnaden vid produktion av VIP:ar. Tre nyutvecklade nanoporösa kiselpulver har testats med olika stationära och transienta metoder. En inom projektet utvecklad testbädd som kan anslutas till TPS instrument (Transient Plane Source sensor), har använts för att mäta värmeledningsförmågan hos kärnmaterial för VIP:ar, vid varierande gastryck och olika mekaniska laster. Slutsatsen blev att transienta metoder är mindre lämpliga för utföra mätningar av värmeledningsförmåga för nanoporösa kiselpulver låg densitet. Avvikelsen i resultaten är dock minimal för densiteter ovan en gräns då värmeledningen genom fasta material blir dominerande jämfört med värmeöverföring genom strålning. Det andra syftet har varit att föreslå ett nytt monteringssystem för VIP:ar som kan användas för att förbättra energieffektiviteten i byggnader som är typiska för Miljonprogrammet. Genom parametrisk analys och dynamiska simuleringar har vi kommit fram till ett förslag på ett nytt monteringssystem för VIP:ar som har utvärderats genom fullskaleförsök i klimatkammare. Resultaten från fullskaleförsöken visar att den nya tekniska lösningen förbättrar väggens U-värde med upp till 56 %. En förbättrad värmegenomgångskoefficienten för väggen i mitten av en VIP blev mellan 0.118 till 0,132 W m-2K-1 och värmeledningstalet centre-av-panel 7 mW m-1K-1 uppnåddes. Detta arbete innehåller dessutom en ny metod för att mäta köldbryggor i anslutningar med hjälp av infraröd termografi. En effektiv värmeledningsförmåga för 10.9 mW m-1K-1 uppnåddes. Resultaten tyder även på att den verkliga termiska prestandan av VIP:ar i konstruktioner är något sämre än mätvärden för paneler i laboratorium. En effektiv värmeledningsförmåga av 10.9 mW m-1K-1 ger dock väggkonstruktionen en utmärkt termisk prestanda. Det tredje syftet har varit att bedöma miljöpåverkan av en VIP-isolerad byggnad, från produktion till drift, eftersom en livscykelanalys av hela byggnader som är isolerade med vakuumisoleringspaneler inte har gjorts tidigare. Slutsatsen var att VIP:ar har en större miljöpåverkan än traditionell isolering, i alla kategorier förutom ozonnedbrytande potential. VIP:ar har en mätbar påverkan på de totala utsläppen av växthusgaser och primärenergianvändningen i byggnader när både produktion och drift beaktas. Miljöpåverkan av de använda VIP:arna är dock positiv jämfört med GWP av en standardbyggnad (en minskning med 6 %) medan primärenergianvändningen ökade med 20 %. Slutsatsen var att ytterligare användning av VIP:ar gynnas av reducerad energiförbrukning och alternativa energikällor i produktionen av nanoporösa kiselpulver medan användningen av alternativa kärnmaterial och återvinning av VIP kärnor kan hjälpa till att minska miljöpåverkan. En känslighetsanalys visade att valet av VIP:ar har en betydande inverkan på miljöpåverkan, vilket ger möjlighet att reducera den totala användningen av primärenergi i en byggnad med 12 % och utsläppen av växthusgaser kan vara minska, så mycket som 11 % när det gäller både produktion och drift under 50 år. Avslutningsvis är det möjligt att dra slutsatsen att VIP:ar är ett mycket konkurrenskraftigt alternativ för att isolera byggnader som är typiska för Miljonprogrammet. Dock krävs ytterligare undersökningar för att minimera de mätbara miljöeffekter som förvärvats i denna LCA-studie för VIP-isolerade byggnader.
QC 20151109
Simulations of heat and moisture conditions in a retrofit wall construction with Vacuum Insulation Panels
Textural and thermal conductivity properties of a low density mesoporous silica material
A study of the thermal conductivity of granular silica materials for VIPs at different levels of gaseous pressure and external loads
Evaluation of the thermal conductivity of a new nanoporous silica material for VIPs – trends of thermal conductivity versus density
A comparative study of the environmental impact of Swedish residential buildings with vacuum insulation panels
ETICS with VIPs for improving buildings from the Swedish million unit program “Miljonprogrammet”
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Agyare, Benjamin A. "INVESTIGATION OF ATOMIC MOTION IN OPTICAL LATTICES VIA INTENSITY CORRELATION MEASUREMENT." Miami University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=miami1186171967.
Повний текст джерела
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Yaselli, Ignacio. "Studying the time response of a vacuum phototriode and measurement of gamma radiation damage to high voltage capacitors and resistors." Thesis, Brunel University, 2008. http://bura.brunel.ac.uk/handle/2438/3018.
Повний текст джерелаАнотація:
A vacuum phototriodes (VPT) are the photodetectors used in the endcaps of the Electromagnetic Calorimeter of the Compact Muon Solenoid experiment at the Large Hadron Collider at CERN. Software, interfacing with the commercial program “SIMION 3D” was written to allow the simulation of the temporal response of the VPT. Applying Ramo’s Theorem enabled the time development of the VPT signal to be calculated. In order to validate the simulations, experiments were performed using a 60 ps laser pulses (λ = 435 nm) incident on a number of VPT samples. The simulation reproduced the basic features of the operation of the VPT such as gain vs. voltage, and gain vs. magnetic field strength. The simulation also confirmed the need for a fine mesh anode to achieve a useful gain when operating at high magnetic fields. The experimental work represents the first measurements of the time response of a VPT when excited with a very fast light pulse. Both the simulated and experimental response from the VPT were observed to be fast (few ns) and quite complex. Discrepancies between the simulated and experimental signals were partially explained by a SPICE model which includes the VPT interelectrode capacitances and lead inductances. We conclude that the VPT are fast photodetectors with an intrinsic response time of order 1ns for this geometry. The VPT high-voltage filter cards, which operate at 1 kV and in an intense radiation environment, are critical components. A number of commercial off-the-shelf high voltage resistors and capacitors were evaluated at gamma doses up to 345 kGy. No significant change in value or leakage current was observed. As a result of these studies we were able to demonstrate that these inexpensive components were suitable for use in the 3100 filter cards subsequently installed in the CMS apparatus.
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EJLLI, Aldo. "PROGRESS TOWARDS A FIRST MEASUREMENT OF THE MAGNETIC BIREFRINGENCE OF VACUUM WITH A POLARIMETER BASED ON A FABRY-PEROT CAVITY." Doctoral thesis, Università degli studi di Ferrara, 2017. http://hdl.handle.net/11392/2488036.
Повний текст джерелаАнотація:
This dissertation work was carried out in the context of the PVLAS experiment, financed by INFN and MIUR, which has the ultimate goal of measuring the magnetic birefringence of vacuum. Photon-photon interaction and therefore magnetic birefringence of vacuum anticipated Quantum Electrodynamics (QED): these effects, already studied since 1936 by Euler, Heisenberg and Weisskopf, are associated with the fluctuations of electron-positron pairs in vacuum. The effective Lagrangian density derived by these scientists was later confirmed by Schwinger in 1951 within the QED formalism. For a 2.5 T magnetic field it is found that the induced vacuum magnetic birefringence is:
∆nEHW = 2.47 × 10^−23 @ 2.5 T.
This birefringence is extremely small and is still waiting for a direct experimental confirmation.
This thesis mainly concerns the new high sensitive polarimeter of the PVLAS experiment. The polarimeter consists of a pair of crossed polarisers, a Fabry-Perot cavity with a high finesse (F = 7 × 10^5) and uses the heterodyne technique to minimise the noise and the systematic effects. The anisotropy of vacuum with respect to electromagnetic radiation is produced using two rotating dipole permanent magnets characterised globally by the parameter integral B^2 dl = 10.25 T2m.
In this thesis work, the experimental apparatus is characterised and the sources of spurious signals and excess wide band noise are studied. As the principal source of spurious signals, we have identified diffused light modulated by a mechanical coupling between the tube and the magnet. A detailed description of the methods used to minimise this magneto-mechanical coupling, as well as other noises and systematic effects, is given. The improvements thus obtained have allowed acquiring data for rather extended periods of time - of a few weeks and this has allowed the improvement of the existing current limits on magnetic vacuum birefringence, reaching a noise floor (1σ c.l.)
∆n(PVLAS) = (12 ± 17)×10−23 @ 2.5 T,
a factor 7 above the predicted QED value.
To reach the predicted QED value a ten fold improvement in sensitivity is necessary. The cause of the excess wide band noise, which is more than a factor 50 above the expected budget, is still unknown. Experimentally it is observed that the noise has a trend ≈ 1/ f α with α between 0.5 and 1.
The problem of the excess wide band noise is common to all the experimental efforts, past and present, intended to measure the vacuum magnetic birefringence. The sensitivity of these experiments and the slope of the spectral noise seem to suggest that the limit may be due to the thermal noise of the mirrors. These remarks, to which this thesis work has also contributed, perhaps will lead to a new understanding of the residual noise of such devices and to the development of useful new experimental methods.Questo lavoro di tesi è stato realizzato nell'ambito dell'esperimento PVLAS, che ha l'obiettivo finale di misurare la birifrangenza magnetica del vuoto. L’esperimento è finanziato dall’INFN e dal MIUR. La birifrangenza magnetica del vuoto, così come lo scattering fotone-fotone, sono previsti dall'Elettrodinamica Quantistica (QED): questi effetti, studiati già a partire dal 1936 da Euler, Heisenberg e Weisskopf, sono associati alle fluttuazioni delle coppie elettrone-positrone nel vuoto. Per un campo magnetico di 2.5 T, la birifrangenza magnetica indotta è: ∆n(EHW) = 2.47 × 10^−23 @ 2.5 T. Si tratta quindi di un effetto estremamente piccolo che è ancora in attesa di una conferma sperimentale diretta. Questo lavoro di tesi riguarda principalmente il nuovo ellissometro ad altissima sensibilità dell’esperimento PVLAS. L'ellissometro è formato da una coppia di polarizzatori incrociati, una cavità Fabry-Perot ad altissima finesse (F = 7 × 10^5), ed utilizza la tecnica eterodina per minimizzare gli effetti di rumore e sistematici. Per rendere il vuoto birifrangente si fa uso di due magneti dipolari rotanti caratterizzati complessivamente dal parametro integrale del B^2 dl = 10.25 T2m. Nel corso del mio lavoro di tesi ho caratterizzato l’apparato sperimentale, ho studiato le sorgenti di segnali spuri, e quelle di rumore in eccesso presente nel polarimetro. Come sorgente principale di segnali spuri è stata individuata la luce diffusa modulata dall’accoppiamento meccanico tra tubo e magnete. Nella tesi descrivo i metodi utilizzati per minimizzare questo accoppiamento magnetomeccanico, così come altri rumori ed effetti sistematici. I miglioramenti così ottenuti hanno permesso di acquisire dati per periodi piuttosto lunghi – dell'ordine di qualche settimana – e ciò ha permesso di migliorare i limiti attualmente esistenti sulla birifrangenza magnetica del vuoto, raggiungendo un livello di rumore (1σ c.l.) ∆n(PVLAS) = (12 ± 17)×10^−23 @ 2.5 T, che è un fattore 7 al di sopra dell'obiettivo costituito dalla previsione della QED. Per arrivare al livello della previsione della QED si dovrà migliorare la sensibilità almeno di un fattore 10. La causa del rumore, che è in eccesso di un fattore 50 rispetto al budget teorico previsto, è tuttora ignota. Sperimentalmente si osserva che il rumore ha un andamento ≈ 1/ f^α con un valore di α compreso tra 0.5 a 1. Il problema del rumore a larga banda è comune a tutti gli apparati, passati e presenti, che vogliono misurare la birifrangenza magnetica del vuoto. L’esame delle sensibilità di questi esperimenti e l'andamento spettrale del rumore sembrano suggerire che il limite possa essere dovuto ad un rumore termico dello specchio. Queste osservazioni, a cui ho contribuito con il mio lavoro di tesi, forse consentiranno di arrivare ad una nuova comprensione del rumore residuo e allo sviluppo di nuovi metodi sperimentali.
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Wang, L. L. "Precision measurement of the e+e− → π + π−(γ ) cross-section with ISR method". Phd thesis, Université Paris Sud - Paris XI, 2009. http://tel.archives-ouvertes.fr/tel-00419963.
Повний текст джерелаАнотація:
Vacuum polarization integral involves the vector spectral functions which can be experimentally determined. As the dominant uncertainty source to the integral, the precision measurement of the %born cross section of $e^+e^-\rightarrow\pi^+\pi^-(\gamma)$ as a function of energy from $2\pi$ threshold to 3GeV is performed by taking the ratio of $e^+e^-\rightarrow\pi^+\pi^-(\gamma)$ cross section to $e^+e^-\rightarrow\mu^+\mu^-(\gamma)$ cross section which are both measured with {\babar\ }data using ISR method in one analysis. Besides that taking the ratio of the cross sections of the two processes can cancel several systematic uncertainties, the acceptance differences between data and MC are measured using the same data, and the corresponding corrections are applied on the efficiencies predicted by MC which can control the uncertainties. The achieved final uncertainty of the born cross section of $e^+e^-\rightarrow\pi^+\pi^-(\gamma)$ in $\rho$ mass region ($0.6\sim0.9$GeV) is 0.54\%. As a consequence of the new vacuum polarization calculation using the new precision result of the $e^+e^-\rightarrow\pi^+\pi^-(\gamma)$ cross section, the impact on the SM prediction of muon anomalous magnetic moment $g-2$ is presented, which is also compared with other data based predictions and direct measurement.
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Klempner, Adam R. "Development of a modular interferometric microscopy system for characterization of MEMS." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-010407-173332/.
Повний текст джерелаАнотація:
Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: vacuum; shape and deformation measurement; MEMS; vibrometry; scanning white light; Interferometry; thermal; vibration. Includes bibliographical references (136-139 leaves ).
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Pilný, Lukáš. "Vysokorychlostní vrtání plechů z hliníkových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229848.
Повний текст джерелаАнотація:
Optimalizace procesu vrtání kovových materiálů vyžaduje minimální tvorbu otřepů a jednotný vzhled vrtaných děr. Cílem práce bylo pochopit roli různých klíčových faktorů, jako řezných podmínek, způsobu upnutí obrobku a geometrie vrtáku, na tvorbu otřepů při vrtání 2 mm plechů tvářené hliníkové slitiny Al99.7Mg0.5Cu-H24, za použití vrtáků o průměru 1,6 a 2 mm, pro dosažení minimalizace tvorby otřepů a zajištění jednotnosti získaných povrchů pro velký počet vrtaných děr v obrobku. Tohoto cíle bylo dosaženo provedením 3 experimentálních testů. První experimentální test byl proveden za účelem sledování vlivu řezné rychlosti a posuvu za otáčku, jakožto rozpoznaných řezných parametrů nejvýznamněji ovlivňujících tvorbu otřepů, na výsledné velikosti vzniklých otřepů a jednotnosti vrtaných děr. V druhém experimentu byl zkonstruován vakuový upínací přípravek, za účelem upnutí vrtaného hliníkového plechu a omezení prostoru pro tvorbu otřepů na výstupní straně vrtání na obrobku, a jeho vlivu na tvorbu otřepů bylo vyhodnoceno. V třetím testu byl vyhodnocen efekt rozdílných geometrií vrtáků na tvorbu otřepů, spolu s dosaženou jednotností vrtaných děr. Výsledky z prvního experimentu prokázaly, že výška a tloušťka otřepů je redukována na obou stranách vrtaného plechu za použití vyšších řezných rychlostí. Při použití vyšších posuvů byla viděna zvětšující se výška a tloušťka otřepů na obou stranách vrtání, s výjimkou výšky otřepů na vstupní straně vrtáku do obrobku, která byla minimálně snížena. Druhý experiment prokázal, že vhodně konstruovaný vakuový upínací přípravek může významně omezit vznik otřepů na výstupní straně vrtáku z obrobku. V třetím experimentu, za použití 3 břitého vrtáku a vhodně konstruovaného vakuového upínací ho přípravku, bylo dosaženo eliminace tvorby otřepů z obou stran vrtaného plechu, společně s naplněním požadavků na jednotný vzhled vrtaných děr a vysoké výrobní produktivity. Takovýto optimalizovaný proces, bez nutnosti použití přídavné operace na odstranění vzniklých otřepů, poskytuje významnou redukci výrobních nákladů. Mimoto jsou poskytnuta doporučení pro další výzkum k dosažení zlepšení ve výrobě.
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Matei, Dinu Gheorghe. "Corrosion generated hydrogen flux measurements using a vacuum gradient." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/MQ48065.pdf.
Повний текст джерела
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Sawyer, Samuel Thomas. "Experimental Studies of Spacecraft Plasma Interactions: Facility Characterization and Initial Measurements." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/33714.
Повний текст джерелаАнотація:
The objectives of this thesis are to characterize the plasma environment of a new vacuum chamber facility at Virginia Tech and to perform initial measurements of plasma flow field for studying spacecraft-plasma interactions using this facility. An argon plasma environment was created using a hot filament cathode plasma source. Flange plates attached to the sides of the vacuum chamber were modified in order to attach various feedthroughs both now and in the future such that a probe array DAQ system could be used to expedite measurement and analysis. A Langmuir probe array was used to measure 3-D plasma flow field in the chamber. A Matlab code was developed for automatic evaluation of the Langmuir probe traces. Two sets of measurements were preformed. The first measurement characterizes the plasma produced by the hot filament cathode in the chamber. Langmuir Probes were used to characterize the plasma environment yielding the following average characteristics: Plasma Potential = 5.5486V, Electron Saturation Current = 0.003421A, Electron Temperature = 1.505eV, and the Plasma Density = 6.806*10^14 m^-3. It was found that for both the spherical and cylindrical probes used in the test facility Rs > Debye length and thus were analyzed under the thin sheath condition. The second measurement attempts to measure the 3-D plasma flow field for plasma flow over a structure composed of 4-inch biased Al box sitting on a biased Al plate. The results show signs of the the generation of the expansion pre-sheath structure at the leading edge of the plate and the box upper surface predicted by numerical models. However, the current diagnostics system does not have the spatial resolution and range as well as the data accuracy required to reach a definitive measurement of plasma presheath and plasma wake.Master of Science
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Peterson, Joshua T. Knowlton S. F. "Vacuum magnetic flux surface measurements made on the compact toroidal hybrid." Auburn, Ala., 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Physics/Dissertation/Peterson_Joshua_48.pdf.
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Hofman, Jiří. "Testovací metody pro hodnocení radiačních efektů v přesných analogových a signálově smíšených obvodech pro aplikace v kosmické elektronice." Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2019. http://www.nusl.cz/ntk/nusl-401588.
Повний текст джерелаАнотація:
The traditional radiation testing of space electronics has been used for more than fifty years to support the radiation hardness assurance. Its typical goal is to ensure reliable operation of the spacecraft in the harsh environment of space. This PhD research looks into the radiation testing from a different perspective; the goal is to develop radiation testing methods that are focused not only on the reliability of the components but also on a continuous radiation-induced degradation of their performance. Such data are crucial for the understanding of the impact of radiation on the measurement uncertainty of data acquisition systems onboard research space missions.
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Sasaki, K., Y. Kawai, and K. Kadota. "Vacuum ultraviolet absorption spectroscopy for absolute density measurements of fluorine atoms in fluorocarbon plasmas." American Institute of Physics, 1997. http://hdl.handle.net/2237/6989.
Повний текст джерела
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Russell, Scott A. "Strain gauge measurements of blade resonance using eddy current excitation in a vacuum spin pit." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2002. http://library.nps.navy.mil/uhtbin/hyperion-image/02sep%5FRussell.pdf.
Повний текст джерелаАнотація:
Thesis (M.S. in Aeronautical Engineering)--Naval Postgraduate School, September 2002.Thesis advisor(s): Raymond P. Shreeve, Garth V. Hobson. Includes bibliographical references (p. 93). Also available online.
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Wilson, Simon J. "Thermal profiles in oxygen vacuum swing adsorption (VSA) : modelling, observations and optimisation." Monash University, Dept. of Chemical Engineering, 2001. http://arrow.monash.edu.au/hdl/1959.1/7766.
Повний текст джерела
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Herranz, Alvarez Juan F. "Minimisation of the wire position uncertainties of the new CERN vacuum wire scanner." Doctoral thesis, Universitat Politècnica de Catalunya, 2016. http://hdl.handle.net/10803/398303.
Повний текст джерелаАнотація:
The particle production of an accelerator is characterised by the accelerated species of particles, by their number and energy. The particle rate is determined by the production cross section, a natural constant and the accelerator dependent parameter luminosity. The luminosity is proportional to the number of particles in each beam and inversely proportional to the particle beam transverse dimensions. The luminosity increases with the particle beam density and therefore the probability of interactions too. To optimize the transverse beam sizes, profile monitors are used to measure parameter depending changes.
Different monitors can provide beam transversal profile measurements (Wire Scanners, Synchrotron Light Monitors, Rest Gas Profile Monitors), however the wire scanner monitor is considered to be the most accurate of all monitors. Wire scanner instruments measure the transverse beam density profile in a particle accelerator by means of moving a thin wire in an intermittent manner.
In the next years the luminosity of the Large Hadron Collider (LHC) will be significantly increased and more accurate beam profile measurement will necessary. The new performance demands a wire travelling speed up to 20 m.s-1 and a position measurement accuracy of the order of few micros. The existing wire scanners does not reach the new requirements as their accuracy achieved is limited by the motorization, the angular position measurement system located outside of the vacuum vessels and the vibration of the thin carbon wire which has been identified as one of the major error sources reducing the knowledge of the wire position. Therefore the development of a new device whose accuracy meets the new requirements was mandatory.
This thesis work aims to provide suitable inputs for the design and operation of this new fast wire scanner in order to minimize the uncertainties in the wire position. To accomplish the aims the understanding of the wire vibrations in such a system is one of the main goals of this work. More specifically, the development of a suitable vibration measurement system and the construction of dynamic models of the system are the two goals aimed. For the new scanner design this work intend to propose, the conceptual design, the optimization of the most critical parts and the operation procedure that will allow the new device to reach the required performances imposed by the forthcoming LHC conditions.La producción de partículas de un acelerador se caracteriza por las especies de partículas aceleradas, por su número y energía. La tasa de partículas se determina a partir de la sección transversal de producción, una constante natural, y de un parámetro que depende del acelerador, la luminosidad. La luminosidad es proporcional al número de partículas por haz e inversamente proporcional a la dimensión transversal de los haces. La luminosidad aumenta con la densidad de partículas y por lo tanto también aumenta la probabilidad de interacciones entre los haces. Para optimizar la sección trasversal del haz, se utilizan monitores de perfil de haz. Diversos tipos de monitores pueden proporcionar mediciones del perfil transversal del haz (Escáneres de hilo, Monitores de luz de sincrotrón, Monitores de análisis de gas residual), sin embargo el escáner de hilo está considerado como el más preciso de todos ellos. Los escáneres de hilo miden el perfil del haz atravesándolo con un hilo muy delgado de manera intermitente. En los próximos años la luminosidad del Gran Colisionador de Hadrones (LHC) se incrementará de manera significativa, por lo que serán necesarios sistemas de medida de perfil de haz más precisos que lo actuales. Las nuevas características, requerirán velocidad de desplazamiento del hilo de hasta 20 ms-1 y una precisión en la medida de posición del hilo de tan solo unas micras. Los escáneres actuales no pueden alcanzar estos requerimientos ya que su precisión está limitada por el sistema de motorización, por el medidor angular de posición que está situado fuera del tanque de vacío y por las vibraciones del hilo, la cuales han sido identificadas como una de las mayores fuentes de error a la hora de conocer la posición real del hilo. Por todo esto, el desarrollo de un nuevo dispositivo cuyas características cumplan los nuevos requerimientos era necesario. Este trabajo de tesis tiene como objetivo proporcionar criterios adecuados para el diseño y operación de un nuevo escáner, con el fin de minimizar las incertidumbres en la posición del hilo. Para lograr estos objetivos, el entender las vibraciones del hilo en un sistema de este tipo es un objetivo primordial. De manera más específica el desarrollo de sistemas de medida de vibración adecuados y la construcción de modelos dinámicos del sistema son los dos objetivos concretos perseguidos por este trabajo. De cara al nuevo diseño, este trabajo pretende proponer un diseño conceptual así como definir los criterios para la optimización de las partes más críticas y establecer un procedimiento de operación que permita al nuevo dispositivo alcanzar los requerimientos impuestos por las futuras condiciones del LHC.
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Dürndorfer, Mario [Verfasser]. "Thermal Micro Sensors for Pressure Measurements in the High, Fine and Rough Vacuum Ranges / Mario Dürndorfer." München : Verlag Dr. Hut, 2017. http://d-nb.info/1140977679/34.
Повний текст джерела
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Zia, Azhar. "Solid-state dye-sensitized solar cells measurements at different pressures and temperatures in a controlled vacuum chamber." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-211099.
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Everett, E. Addison. "Design and Characterization of a Time-of-Flight Mass Spectrometer for Composition Measurements in the Upper Atmosphere." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/5698.
Повний текст джерелаАнотація:
In-situ composition measurements of the mesosphere/lower thermosphere (MLT) are challenging; this region is only accessible via high-speed sounding rockets, ambient pressures extend into the 10-3 Torr range, and particles of interest range in mass from electrons to meteoric smoke and dust particles. Time-of-flight mass spectrometers (TOF-MS) are capable of making fast, accurate measurements over a wide mass range. However, since they rely on pressure-sensitive microchannel plate (MCP) detectors and high voltages, they have rarely been applied at these altitudes. A new TOF-MS for making in-situ composition measurements in the MLT has been developed at the Space Dynamics Laboratory. This instrument employs modest acceleration potentials and a pressure-tolerant MCP detector. A Bradbury-Nielsen gate is used to produce short, well-defined ion pulses to reduce the temporal and spatial uncertainty of sampled ions. A prototype TOF-MS was constructed and used to demonstrate TOF-MS technology under conditions relevant to in-situ MLT measurements. Operational boundaries and capabilities of this new instrument were identified through laboratory experiments combined with computer modeling. The prototype instrument achieved a maximum resolution of 100 at m/z 40 (Ar), sufficient to resolve major atmospheric species of interest. During experiments at elevated pressures, the MCP detector maintained low background count rates (/second) at pressures as high as 10-3 Torr. A novel getter-based vacuum system was evaluated for use with the new TOF-MS, and a computer model was developed to simulate instrument pressure during a rocket flight. Results from these experiments suggest that when combined with an appropriately sized sampling aperture, this pumping system can extend the measurement range of the instrument to lower altitudes by 10 – 20 km, compared to an unpumped instrument. A computer model was developed to study the effects of critical operating parameters on instrument performance; the most important factor affecting resolution was found to be the initial energy spread of sampled ions. Sensitivity and number density measurement analyses suggest the new instrument will measure major species in the MLT at better than 10% uncertainty. Composition measurements made with the new TOF-MS will contribute to a better understanding of the MLT.
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Beermann, Rüdiger [Verfasser]. "Structured Light Sensor with Affine Stereo Camera Pair for Geometry Measurements of High-Temperature Components in Rough Vacuum / Rüdiger Beermann." Garbsen : TEWISS - Technik und Wissen GmbH, 2021. http://d-nb.info/1229012583/34.
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Radeck, Désirée [Verfasser]. "Nuclear Structure Studies in the A ~ 100 Mass Region including g-Factor Measurements using Nuclear Deorientation of Recoils into Vacuum / Désirée Radeck." München : Verlag Dr. Hut, 2013. http://d-nb.info/1035050072/34.
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Rimbaud, Christian. "Contribution aux mesures physiques utilisant une source modulée de rayonnement appliquée aux installations nucléaires." Grenoble 1, 1987. http://www.theses.fr/1987GRE10005.
Повний текст джерелаАнотація:
Le but de ces mesures est de determiner certaines caracteristiques d'un milieu physique par utilisation d'une source de rayonnement (neutron ou gamma) et des techniques appropriees de traitement du signal (moyennage, transformee de fourier). Grace a un systeme de modulation de la source, la transformee de fourier permet d'extraire le signal du bruit de fond (provenant soit du systeme de mesure, soit du milieu physique). Les applications etudiees sont la mesure du taux de vide dans la branche chaude d'un rep par transmission gamma modulee et la mesure de quantite de matieres fissiles dans les usines de retraitement par utilisation d'une source de neutrons
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Härtel, Martin [Verfasser], and Thomas M. [Akademischer Betreuer] Klapötke. "Studies towards the gas-phase detection of hazardous materials by vapor pressure measurements with the transpiration method in combination with vacuum outlet GC/MS / Martin Härtel ; Betreuer: Thomas M. Klapötke." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2017. http://d-nb.info/1144857244/34.
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Bilgen, Suheyla. "Dynamic pressure in particle accelerators : experimental measurements and simulation for the LHC." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP020.
Повний текст джерелаАнотація:
L’obtention de très faible pression (UHV) est une condition essentielle pour les accélérateurs de particules de haute énergie et de hautes performances. Par conséquent, la compréhension de l'évolution de la pression dynamique pendant le fonctionnement des accélérateurs est fondamentale afin de trouver des solutions qui permettent de minimiser les hausses de pression induites par de multiples phénomènes présents dans les lignes faisceaux. Pour le LHC, l'apparition d'instabilités peut être due à la succession de plusieurs processus. Tout d’abord, le faisceau de protons de haute intensité ionise le gaz résiduel, produisant des ions positifs (principalement H₂⁺ et CO⁺) ainsi que des électrons qui sont accélérés et qui impactent la paroi en cuivre des tubes de faisceaux. Ensuite, ces interactions induisent : (i) une désorption des gaz absorbés sur les parois, conduisant à des élévations de pression ; (ii) la création de particules secondaires (ions et électrons). Dans ce dernier cas, la production d'électrons secondaires entraîne, par effet d’avalanche, la formation de nuages d’électrons, dont la limitation est l'un des enjeux majeurs de l'anneau de stockage du LHC. Ces nuages génèrent des montées de pression et des dépôts de chaleur sur les parois du collisionneur pouvant conduire à des « quench » d’aimants supraconducteurs. Tous ces phénomènes limitent l'intensité maximale et augmentent l’émittance des faisceaux et donc la luminosité ultime atteignable dans un accélérateur de protons. Ce travail de thèse a pour but d’étudier certains phénomènes fondamentaux qui contrôlent la pression dynamique dans le LHC, à savoir les effets induits par les électrons et les ions, d’une part, et l'influence de la chimie de surface du cuivre constituant les écrans faisceaux, d’autre part. Dans un premier temps, les courants d’électrons et d’ions ainsi que la pression ont été mesurés in situ dans le Secteur Pilote Vide (VPS) situé sur l'anneau du LHC pendant la deuxième période d’exploitation du collisionneur. En analysant ces résultats, une quantité d’ion plus importante que prévu a été détectée et la relation entre les électrons, les ions et les variations de pression a été étudiée. D’autre part, la désorption stimulée par les ions a été mesurée au laboratoire au CERN en utilisant un bâti expérimental dédié. L'influence de la nature, de la masse et de l'énergie des ions incidents interagissant avec les surfaces sur les rendements de désorption ionique a été discutée. De plus, des analyses approfondies de la surface de cuivre constituant l'écran faisceau ont été réalisées dans le laboratoire IJCLab pour identifier le rôle joué par la chimie de surface du cuivre sur le rendement d’émission électronique, les processus de conditionnement de surface et la désorption de gaz stimulée. Le rôle fondamental de composés chimiques sur la surface (contaminants, présence de carbone et d'oxydes natifs) sur le rendement de production des électrons secondaires a été mis en évidence. Enfin, nous avons proposé un code de simulation permettant de prédire les profils de pression dans les chambres à vide des accélérateurs de particules ainsi que leur évolution temporelle. Ce nouveau code de simulation appelé DYVACS (DYnamic VACuum Simulation) est une amélioration du code VASCO développé par le CERN. Il a été appliqué pour simuler la pression dynamique dans le VPS. L'évolution du nuage d'électrons a été implémentée dans le code via des « maps » permettant de calculer l'évolution de la densité des nuages d'électrons. L'ionisation du gaz résiduel par les électrons a également été prise en compte. Finalement, les résultats obtenus avec DYVACS ont été comparés aux mesures de pression enregistrées dans le LHC. Les résultats obtenus à l’issu de ces travaux de thèse, ainsi que les développements expérimentaux et de simulation réalisés, pourront permettre l’étude de la stabilité du vide de futurs accélérateurs de particules tels que HL-LHC ou FCC(ee et hh)Ultra-High Vacuum is an essential requirement to achieve design performances and high luminosities in high-energy particle colliders. Consequently, the understanding of the dynamic pressure evolution during accelerator operation is fundamental to provide solutions to mitigate pressure rises induced by multiple-effects occurring in the vacuum chambers and leading to beam instabilities. For the LHC, the appearance of instabilities may be due to the succession of several phenomena. First, the high intensity proton beams ionize the residual gas producing positive ions (mainly H₂⁺ or CO⁺) as well as accelerated electrons which impinge the copper wall of the beam pipe. Then, these interactions induce: (i) the desorption of gases adsorbed on the surfaces leading to pressure rises; (ii) the creation of secondary particles (ions, electrons). In this latter case, the production of secondary electrons leads to the so-called “Electron Cloud” build-up by multipacting effect, the mitigation of which being one of the major challenges of the LHC storage ring. Electron clouds generate beam instabilities, pressure rises and heat loads on the walls of beam pipe and can lead to “quench” of the superconducting magnets. All these phenomena limit the maximum intensity of the beams and thus the ultimate luminosity achievable in a proton accelerator. This work aims to investigate some fundamental phenomena which drive the dynamic pressure in the LHC, namely the effects induced by electrons and ions interacting with the copper surface of the beam screens on the one hand and the influence of the surface chemistry of copper on the other hand. First, in-situ measurements were performed. Electron and ion currents as well as pressure were recorded in situ in the Vacuum Pilot Sector (VPS) located on the LHC ring during the RUN II. By analyzing the results, more ions than expected were detected and the interplay between electrons, ions and pressure changes was investigated. Then, the ion-stimulated desorption was studied, using a devoted experimental set-up at the CERN vacuum Lab. The influence of the nature, mass, and energy of the incident ions interacting with the copper surface on the ion-desorption yields was discussed. In addition, extensive surface analyses were performed in the IJCLab laboratory to identify the role played by the surface chemistry on the electron emission yield, surface conditioning processes and the stimulated gas desorption. The fundamental role of the surface chemical components (contaminants, presence of carbon and native oxide layers) on the secondary electron yield was evidenced. Finally, we proposed a simulation code allowing to predict the pressure profiles in the vacuum chambers of particle accelerators as well as their evolution under dynamic conditions (i.e. as a function of time). This new simulation code called DYVACS (DYnamic VACuum Simulation) is an upgrade of the VASCO code developed at CERN. It was applied to simulate the dynamic pressure in the VPS when proton beams circulate into the ring. The electron cloud build-up was implemented in the code via electron cloud maps. The ionization of the residual gas by electrons was also considered. Results obtained with the DYVACS code are compared to pressure measurements recorded during typical fills for physics and a good agreement is obtained. This PhD study has provided interesting results and has allowed the development of new experimental and simulation tools that will be useful for further investigations on the vacuum stability of future particle accelerators such as HL-LHC or FCC (ee and hh)
35
LORENZATI, ALICE. "Super Insulating Materials for energy efficient buildings: thermal performance and experimental uncertainty." Doctoral thesis, Politecnico di Torino, 2018. http://hdl.handle.net/11583/2711530.
Повний текст джерелаАнотація:
In a global energy-saving policy, Super Insulating Materials (SIMs) represent an effective solution, especially in a world almost saturated with old buildings for which energy refurbishments are needed. Given their extremely low thermal conductivity, they allow reaching an excellent insulation level, with reduced thicknesses. Anyway, they are recent materials or at least recent insulation solutions for the building sector. And as all the new technologies, they bring with them some critical issues to be solved. For example, what is the accuracy of their available thermal conductivity, what are the criteria for their optimal laboratory characterisation, what are their actual thermal performances in situ and how long is their durability and what is their practical convenience still remain open questions.
The aim of this research was to provide an answer to these questions, although sometimes in a preliminary way.
Therefore, the thermal properties of SIMs (and in particular of the Vacuum Insulation Panels, since, between the SIMs they are the most performing and the most critical solution) were explored at different levels, from the material/panel scale to the building scale.
SIMs are actually laboratory tested using traditional experimental apparatuses, such as the Heat Flow Meter (HFM) and the Guarded Hot Plate (GHP), and in accordance with as traditional standard, developed for the most common insulating material. Indeed, at the first stage of this research, the applicability of the current methodologies was extensively verified, with an in-depth analysis of the obtainable measurement uncertainties. The uncertainty assessment was performed in three different ways, to analyse the various scenarios that may occur: a theoretical standard based uncertainty evaluation, and both the Type A and Type B experimental uncertainty assessment.
Once defined the best criteria for a proper evaluation of the SIMs thermal properties, they were experimentally characterised, considering the different parameters which could have some effects on their thermal behaviour (different thicknesses, average testing temperature, temperature difference, ageing conditions and so on).
In practical applications of the VIPs, they must be assembled one to each other: innovatively, both the HFM and GHP apparatuses were also used for the evaluation of the linear thermal transmittance of the thermal bridges that occur in case of VIPs assemblies. The investigation performed at the material/panel level were then repeated at the component scale, to evaluate the variability and the measurement uncertainty of the linear thermal transmittance.
The so defined thermal performances represented a reliable pool of input data for the dynamic hygrothermal simulations at the building scale. The goals were the evaluation of the energy efficiency of building insulated with SIMs and the prediction of the durability of these materials (considering different severities of the building envelope component boundary conditions).
The outputs of the numerical simulations were then coupled with an economic analysis, to evaluate the convenience of VIP insulation, in terms of discounted pay-back period.
36
Terschlüsen, Joachim A. "Constructing and Commissioning HELIOS – A High Harmonic Generation Source for Pump-Probe Measurements with sub 50 fs Temporal Resolution : The Development of Experimental Equipment for Extreme Ultraviolet Spectroscopy." Doctoral thesis, Uppsala universitet, Molekyl- och kondenserade materiens fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-281298.
Повний текст джерелаАнотація:
This thesis presents HELIOS, an in-house laboratory for time-resolved pump-probe spectroscopy with extreme-ultraviolet (XUV) probe radiation. A wide span of pump wavelengths can be generated using commercial laser equipment while XUV probe radiation is generated via a high harmonic generation process in a noble gas delivering probe photons with energies between 20 eV and 72 eV. The XUV beam path features a time-preserving monochromator and was constructed and built in-house. HELIOS features an overall time resolution of about 50 fs when using 800 nm pump and 41 eV probe photons. An energy resolution of 110 meV at 41 eV photon energy can be achieved. HELIOS features two beamlines. One µ-focus beamline with an XUV focal size of about 20 µm can be used with experiments that require such a small XUV focal size as well as with different end stations. The other beamline features a semi-permanently mounted end station for angle-resolved photoelectron spectroscopy under ultra-high vacuum conditions. Experiments demonstrating the usability of HELIOS and the two beamlines are presented. A pump-probe measurement on graphene demonstrates the capability of determining a large part of the k-space in only one measurement due to the use of an ARTOF angle-resolved time-of-flight electron spectrometer. A non-angle-resolved pump-probe measurement on the conducting polymer PCPDTBT demonstrates the high signal-to-noise ratio achievable at this beamline in non-angle-resolved photoelectron-spectroscopy pump-probe measurements. The usability of the µ-focus beamline is demonstrated with time-resolved measurements on magnetic samples employing an in-house-designed spectrometer. These experiments allow the retrieval of element-specific information on the magnetization within a sample employing the transversal magneto-optical Kerr effect (T-MOKE). Additionally, a Fourier transform spectrometer for the XUV is presented, the concept was tested at a synchrotron and it was used to determine the longitudinal coherence of the XUV radiation at HELIOS.
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Müller, Jan. "Kondenzační technika a odvody spalin." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2014. http://www.nusl.cz/ntk/nusl-226844.
Повний текст джерелаАнотація:
This thesis is developed as a proposal for heating for a primary school and kindergarten in the region of Brno-countryside. For the insulated building, a combination of heating and air-conditioning is proposed. The concept is designed so that the air-conditioning preheats the exterior air and the heating system warms the incoming air to a comfortable temperature. For the required thermal performance, sources of heat (for gas and pellets) and a layout solution for the boiler room is designed. Drainage of combustion products is proposed for both solutions. The project solution is per the extent of the construction permit. The theoretical part is linked with the practical part through the condensation boilers, their function and division, and drainage of combustion products. The experiment for the given topic was conducted on the drainage of combustion products. The pressure loss of the reverse knob was determined in relation to the flow rate of air in the condensation boilers as this loss is essential in assessing the drainage of combustion products.
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Ruess, Frank Joachim Physics Faculty of Science UNSW. "Atomically controlled device fabrication using STM." Awarded by:University of New South Wales. Physics, 2006. http://handle.unsw.edu.au/1959.4/24855.
Повний текст джерелаАнотація:
We present the development of a novel, UHV-compatible device fabrication strategy for the realisation of nano- and atomic-scale devices in silicon by harnessing the atomic-resolution capability of a scanning tunnelling microscope (STM). We develop etched registration markers in the silicon substrate in combination with a custom-designed STM/ molecular beam epitaxy system (MBE) to solve one of the key problems in STM device fabrication ??? connecting devices, fabricated in UHV, to the outside world. Using hydrogen-based STM lithography in combination with phosphine, as a dopant source, and silicon MBE, we then go on to fabricate several planar Si:P devices on one chip, including control devices that demonstrate the efficiency of each stage of the fabrication process. We demonstrate that we can perform four terminal magnetoconductance measurements at cryogenic temperatures after ex-situ alignment of metal contacts to the buried device. Using this process, we demonstrate the lateral confinement of P dopants in a delta-doped plane to a line of width 90nm; and observe the cross-over from 2D to 1D magnetotransport. These measurements enable us to extract the wire width which is in excellent agreement with STM images of the patterned wire. We then create STM-patterned Si:P wires with widths from 90nm to 8nm that show ohmic conduction and low resistivities of 1 to 20 micro Ohm-cm respectively ??? some of the highest conductivity wires reported in silicon. We study the dominant scattering mechanisms in the wires and find that temperature-dependent magnetoconductance can be described by a combination of both 1D weak localisation and 1D electron-electron interaction theories with a potential crossover to strong localisation at lower temperatures. We present results from STM-patterned tunnel junctions with gap sizes of 50nm and 17nm exhibiting clean, non-linear characteristics. We also present preliminary conductance results from a 70nm long and 90nm wide dot between source-drain leads which show evidence of Coulomb blockade behaviour. The thesis demonstrates the viability of using STM lithography to make devices in silicon down to atomic-scale dimensions. In particular, we show the enormous potential of this technology to directly correlate images of the doped regions with ex-situ electrical device characteristics.
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Tsai, Chien-Chuan, and 蔡健全. "Investigation on Vibration Measurement procedure of Vacuum Pump Equipment." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/13069606490620189108.
Повний текст джерелаАнотація:
碩士國立中興大學
機械工程學系所
97
This text takes Edwards vacuum pumps as the instance to analyze and illustrate the standard operational procedure for executing the regular examination and maintenance. Using vibration spectrum analyzer measures the vibration of the vacuum pumps in order to diagnose and analyze the examined equipment. Through the progress of the measurement by vibration spectrum analyzer and the result from the diagnosis and analysis, a standard procedure for examining vibration and a method for troubleshooting are established. In addition, using the application of measuring vibration and the standard operational procedure for executing the regular examination and maintenance in the semiconductor factories is also discussed in this text. Each factory can establish its own work flow for regular equipment examination and maintenance during the manufacturing process. They even can further develop or standarize other types of work flow for the equipment examination. Compared with the loss caused by unexpected machinery breakdown, the annual costs that the internal industries spend on servicing and mantaining their rotational mechanical equipment are actually much cheaper. Therefore, in default of proper maintainance or failing to control the use status of equipment, it may end in the machinery damaged even the breakdown and that will really cost the internal industries a lot of money.
40
Jian, Jia-xian, and 簡嘉賢. "Fabrication and Measurement of CMOS MEMS-Based Thermoelectric Vacuum Sensor." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48574613951290320930.
Повний текст джерелаАнотація:
碩士國立高雄應用科技大學
光電與通訊工程研究所
102
This paper presents the measurement and the fabrication of thermocouple vacuum sensors fabricated by a low cost CMOS process and MEMS technology. The thermocouple vacuum sensors have two types of suspended structures with different solid thermal conductance. The vacuum sensor with shorter supporting leads and larger solid conductance was named TP401 and the other one was TP402. Each suspended structure was formed by using <100> silicon anisotropic etching process after the CMOS process and has a polysilicon heater and an aluminum/polysilicon thermocouple pair. The polysilicon heater also serves as a thermistor temperature sensor. The performances of the sensors were characterized in this work. Furthermore, an AC electrical modulation method using a lock-in amplifier was adopted for improving the signal-to-noise ratio of the measurement of the sensors. The thermal conductance of TP401 and TP402 were evaluated as 73.83uW/K and 79.2uW/K according to the ratio of bias heating power to temperature difference between the hot junction and the cold junction of the thermocouple. The thermocouple output voltage was about 13mV as the power of heater was 2.5mW. The thermal time constants of these sensors were also figured out by adopting the measurement of infrared frequency response of the thermocouple vacuum sensors in air and in vacuum respectively. The measurement results show that the thermal time constants of TP402 were 15ms and 220ms at atmospheric pressure and in vacuum environment respectively. The pressure response measurement of the vacuum sensors using DC bias will result in an 8-10mV voltage fluctuation and lower the signal-to-noise ratio. The signal fluctuation could be improved to 0.3mV by using an AC electrical modulation.
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Almeida, Pedro Gonçalo Dias de. "Cylindrical spinning rotor gauge — A new approach for vacuum measurement." Master's thesis, 2015. http://hdl.handle.net/10362/15999.
Повний текст джерелаАнотація:
The spinning rotor gauge (SRG) is one of the most interesting vacuum gauges ever
made, covering a pressure range of over seven orders of magnitude, with minimal gas
interference (no pumping, ionization or heating of the measured gas), and a great stability of less than 1% drift per year.
But despite its remarkable properties, apparently the SRG has not been further developed since the eighties, when it gained commercial interest.
In this context, this dissertation aims at providing a starting point for a new line of
investigation regarding this instrument, focused on the rotor itself.
A brief study of different rotor geometries is provided, including a comparison between
a cylindrical rotor and a spherical one. A cylindrical spinning rotor gauge (CSRG) is then proposed, based on the original SRG, but requiring a completely new lateral damping system. A prototype was built and tested against a non calibrated reference gauge.
42
Lin, Che-Yu, and 林哲宇. "Development of clamped-clamped beam type piezoelectric sensor for vacuum pressure measurement." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/45619720375140636940.
Повний текст джерелаАнотація:
碩士國立中興大學
機械工程學系所
100
In this thesis, a clamped-clamped beam type piezoelectric vacuum pressure sensor was developed. The piezoelectric beam fixed at both ends consists of a PZT layer perfectly bonded to the copper substrate. The dimensions of the PZT layers and copper substrate are both 20mm × 5mm × 200μm. Two pairs of electrodes cover the surfaces of the PZT at the bottom and top layers near both ends. Input voltage was applied at one pair of electrodes to vibrate piezoelectric beam and output voltage was measured at the other pair of electrodes. Experimental results showed that developed pressure sensor has a wide range from 6.5×10-6 to 760Torr. Output voltage generated by vibrations of beams which were varied by viscous gas damping forces acting on the beams in the vacuum. Damping forces can be calculated from damping ratio by half power method experimentally. Damping ratio of sensor includes the effect of strain rate damping and viscous gas damping. The strain rate damping is assumed to be proportional to the bonding stiffness of beam and gas damping is assumed to be changed by the pressure. Experimental results showed that output voltages of sensors were proportional to gas damping ratio. It indicated vacuum pressures can be estimated from output voltage. Vacuum pressures of nitrogen and argon are also compared. Experimental results showed that the gas damping ratio of argon is greater than the damping ratio of nitrogen. Piezoelectric outputs and damping ratios are in the same trend with the vacuum pressures.
43
Liao, Yi-Kai, and 廖釔凱. "Magneto-optical Kerr Effect Measurement with Pulsed Magnetic Field in High Vacuum." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/djn3a6.
Повний текст джерелаАнотація:
碩士中原大學
物理研究所
106
The surface magneto-optical Kerr effect measurement in high vacuum was performed with a millisecond-pulsed magnetic field, which is generated from the controlled discharge of capacitors to the coils. The theoretical simulation is used to obtain the strong and uniform pulsed magnetic field. Compared with the conventional electromagnet, pulsed magnetic field is faster. The maximum field strength can be improved by increasing the charging voltage. A nickel film on the SiO2 is used as the test sample, and its magnetic hysteresis loop was successfully obtained. The magnetic coercive, remanence, and hysteresis curve characteristics of the magnetic film were observed. The results were consistent with the measurement methods of other periodicals. Verify the accuracy of this device measurement. This technique can be applied to the study of the dynamic magnetic properties in the future.
44
Dhruva, Shirhatti Vijay. "Development of Graphene Based Sensors for Human Physiological Monitoring and Vacuum Measurement." Thesis, 2021. https://etd.iisc.ac.in/handle/2005/5412.
Повний текст джерелаАнотація:
Nanomaterials have emerged as a remarkable class of materials in recent years owing to their excellent electrical, chemical, and physical properties. The first two-dimensional (2D) material to be discovered, graphene, has been the torchbearer in this regard with its superlative properties and a strong impact on numerous technologies. Sensor technology is one such space where nanomaterials have brought an impressive facelift. A new genre of sensors was imperative in the biomedical field where the existing brittle and rigid wafer-based electronics have their limitations. The present talk describes my work accomplished in the synthesis of graphene and innovative device fabrication techniques, which has led to sensors that are highly sensitive, flexible, stretchable, and skin-conformal, notably preferred in biomedical sensing technology. These flexible wearable sensors see potential service in monitoring human physiological parameters, like heart rate, breathing rate, body temperature, body de-hydration, limb movement, tactile sensing, and so on. These sensors have a direct impact on the well-being of the masses, especially considering the current crisis in healthcare systems. Another area identified for possible improvement using nanomaterials is the vacuum sensing technology in industrial applications, which has not seen significant improvement over a long period of time. Vacuum technology has far-reaching utilization in areas like medical equipment, water treatment and petrochemical plants, food and beverages industry, space technology, semiconductor industry, thin-film technology, nuclear and defense requirements, and so forth. The limitations of available vacuum measurement devices such as narrow operating range, large form factor, expensive and need for cascaded gauges can be addressed using the developed vacuum sensor based on graphene nanocomposite.
This talk summarizes the research carried out towards the design and development of graphene-based sensors targeting the above-described domains. The work includes a graphene supercapacitor model-based strain sensor with high noise immunity for biomedical applications. A multifunctional piezoresistive sensor with graphene nanosheets with a focus on commercially viable wearable devices has been developed for vital biomonitoring requirements. Further, graphene nanocomposite with gas chemisorption property has been explored for vacuum pressure measurement for a broader scope of applications. The developed sensor prototypes based on graphene nanomaterial have given a fresh perspective in the field of sensor technology.
45
Chen, Cheng-Li, and 陳政利. "Development and Electrical Measurement of Vacuum Spacers for Field Emission Flat Panel Displays." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/82081610427665408589.
Повний текст джерелаАнотація:
碩士國立交通大學
工學院半導體材料與製程設備學程
99
Field-emission flat panel displays (FE-FPD) require a high-vacuum operation condition to optimize the life-time of electron field-emitters; this requirement needs vacuum spacers to be placed between the cathode plate comprising field-emitters and the screen plate to withstand the atmospheric pressure. Vacuum spacers are made of insulators so that the cathode and the screen plates are free from electrical breakdown. However, as the field-emitted electrons from the cathode strike the screen plate, backscattered electrons may impinge on the insulating spacers resulting in secondary electron (SE) emission from the spacers. Because the SE yield is larger than one for most materials, the SE emission will render the spacers positively charged, thereby modifying the local electric field; the modification can change the trajectory of the field-emitted electrons resulting in image distortion. To overcome the adverse effect of the SE emission, we fabricated porous coatings anodic aluminum oxide (AAO) and porous TiO2 thin films on glass to minimize the SE yield of the spacer. Because the porous structure can trap secondary electrons, which have a low kinetic energy and a very shallow escape depth, the SE yield can be significantly reduced. We studied the relative SE yield of the two types of spacers in an Auger electron spectrometer using a specially designed sample holder. The surface roughness, the adhesion strength and the electrical resistance of the coatings were also studied. The porous coatings demonstrated good electrical and mechanical properties, which are suitable for the use of vacuum spacers in FE-FPDs。We have successfully fabricated uniform porous AAO and porous TiO2 coatings on the large substrate with a surface area of 24 x 60 mm2.
46
Gleason-Rohrer, David Charles. "Measurement of the Band Bending and Surface Dipole at Chemically Functionalized Si(111)/Vacuum Interfaces." Thesis, 2014. https://thesis.library.caltech.edu/8032/1/GleasonRohrer2013thesis.pdf.
Повний текст джерелаАнотація:
The core-level energy shifts observed using X-ray photoelectron spectroscopy (XPS) have been used to determine the band bending at Si(111) surfaces terminated with Si-Br, Si-H, and Si-CH3 groups, respectively. The surface termination influenced the band bending, with the Si 2p3/2 binding energy affected more by the surface chemistry than by the dopant type. The highest binding energies were measured on Si(111)-Br (whose Fermi level was positioned near the conduction band at the surface), followed by Si(111)-H, followed by Si(111)-CH3 (whose Fermi level was positioned near mid-gap at the surface). Si(111)-CH3 surfaces exposed to Br2(g) yielded the lowest binding energies, with the Fermi level positioned between mid-gap and the valence band. The Fermi level position of Br2(g)-exposed Si(111)-CH3 was consistent with the presence of negatively charged bromine-containing ions on such surfaces. The binding energies of all of the species detected on the surface (C, O, Br) shifted with the band bending, illustrating the importance of isolating the effects of band bending when measuring chemical shifts on semiconductor surfaces. The influence of band bending was confirmed by surface photovoltage (SPV) measurements, which showed that the core levels shifted toward their flat-band values upon illumination. Where applicable, the contribution from the X-ray source to the SPV was isolated and quantified. Work functions were measured by ultraviolet photoelectron spectroscopy (UPS), allowing for calculation of the sign and magnitude of the surface dipole in such systems. The values of the surface dipoles were in good agreement with previous measurements as well as with electronegativity considerations. The binding energies of the adventitious carbon signals were affected by band bending as well as by the surface dipole. A model of band bending in which charged surface states are located exterior to the surface dipole is consistent with the XPS and UPS behavior of the chemically functionalized Si(111) surfaces investigated herein.
47
ČEPIČKA, Josef. "Využití elektronek v současné době." Master's thesis, 2014. http://www.nusl.cz/ntk/nusl-170201.
Повний текст джерелаАнотація:
Aim of this thesis is to construct a demonstration model of a vacuum tube amplifier with a possibility of measurement of signal on more places and a possibility to see the wiring and construction of the amplifier. The first part of the work treats some important themes concerning vacuum tubes and wiring with them, for example a principle of signal intensification by vacuum tubes, categories of low-frequency amplifiers and description of several types of undesirable distortions. Next part deals with the design of the constructed amplifier, the description of the construction itself and placement of the components on the printed circuit boards and used vacuum tubes and transformers. The following part is focused on measurement of the basic properties of the amplifier and vacuum tubes by means of TESLA BM215A appliance. The final part contains technical parameters of the amplifier and photo documentation.
48
Chung, Chao-Kai, and 鍾朝凱. "Using the Excitation Surface Plasma Waves of Optical Frustrated Total Internal Reflection to the Vacuum Measurement System." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/15257866893693515866.
Повний текст джерелаАнотація:
碩士清雲科技大學
電子工程研究所
94
The research is excitation of surface plasma wave (SPW) in thin metal film by the method of optical frustrated total internal reflection (OFTIR) to the vacuum. The research used Otto configuration and Kretschmann configuration to exciting surface plasma waves. In recent years, the vacuum is the technique to applied of widely in the industry. The vacuum purity is effect to the quality of a lot of developments of industry. Used vacuum pump is extract the air from the vacuum. The purpose is change surface plasma waves resonant angle , and examines purity of the vacuum. This technique to adopt dielectric constant of change achieve vacuum purity of measure. Because of gaseous components and density content is different in the air. When extract the vacuum , the dielectric constant will change the components and content .That change of the dielectric constant is precisely this measure technique of quality. The technology is different from vacuum measurement system. The new technology use surface plasma waves to measure purity in vacuum. This paper will be application computer to simulate.
49
FU, JUN-QING, and 傅浚清. "The Study of Contact and Wear Surface of Sliding Vane in Rotary Vacuum Pump By Ultrasonic Measurement." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/uatk5q.
Повний текст джерелаАнотація:
碩士國立高雄科技大學
模具工程系
107
This experiment was conducted to do research on the difference of wear down of putting pressure on abraded sliding vane in rotary vacuum pump, with non-contact measurement applied to this experiment, an ultrasonic measurement was used to scan the whole surface of contacted area. If there is no contact with the area, which detected by the wave sent from the ultrasonic detection equipment, the wave will reflect and absorb by the equipment receiver. If there exists contact, some waves will be transmitted to the sliding vane in rotary vacuum pump. Thus, the signal reflects to the detection equipment will weaken, therefore, we can realize the exposure degree from signal descending values, which comes from a fully scan of the ultrasonic detection equipment on the sliding vane in rotary vacuum pump. The experiment measured the variation between the contact area and the contact ratio of the difference pressure on sliding vane in rotary vacuum pump. As result indicated, the contact area of the sliding vane in rotary vacuum pump used by 5kg/cm2 will be within 480mm2 to 660mm2, and would be increased within 1200mm2 to 1800mm2 after putting more pressure one the contact area. As the contacted area of the sliding vane in rotary vacuum pump become more uneven, the abrasion become more obvious. Also, the different analytic data will be acquired by the observation of abrasion of the slideing vane in rotary vacuum pump by ultrasound and the difference of measuring contact area. The aforementioned data will determine that when the sliding vane need to be changed cost-effectively.
50
吳賢逸. "The modal analysis and measurement of the dry film lamination pre-cut device of a semiconductor wafer vacuum modeling machine." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/03033820436429912078.
Повний текст джерелаАнотація:
碩士國立彰化師範大學
機電工程學系
99
The objective of this study is to study the mode shape and natural frequency of the dry film lamination pre-cut device of a semiconductor wafer vacuum modeling machine. The Pro/E is employed to construct the 3D model and do the modal analysis. The simulation result is verified by modal test. The spectrum analyzer, three-axis accelerometer and percussion hammer are used to obtain the testing data. The result shows that the natural frequency obtained from finite element analysis and impact testing are coincident; they are: for the first four modes, 26.07Hz, 33.08Hz, 38.00Hz and 53.28. All the errors are within 5%. The results of this study should guide to better future designs of the equipment and are vital to reliable and safe operations of these devices.