Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Material of the baffle.
Дисертації з теми "Material of the baffle"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 дисертацій для дослідження на тему "Material of the baffle".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Hunt, Cassandra R. "Baffle material characterization for Advanced LIGO." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44820.
Повний текст джерелаАнотація:
Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.Includes bibliographical references (p. 43-45).
The transition to Advanced LIGO introduces new sensitivity requirements for the LIGO interferometers. When light scatters away from the main laser beam, then scatters off the beam tube and returns to the main beam, noise is introduced into the phase of the laser. The Auxiliary Optics Support subsystem uses baffles and beam dumps to control this scatter, but the baffle material and shape contribute some scatter as well. Careful selection of baffle material for Advanced LIGO is necessary in order to minimize baffle backscatter. Characterization of potential materials will also inform the geometry and placement of baffles. To this end, I developed a scatterometer experiment designed to measure the Bidirectional Reflectance Distribution Function (BRDF) of a material. The arrangement was used to measure the BRDF for black welder's glass, the prime candidate material for baffles in Advanced LIGO. I found that black glass has a BRDF on the order of 10-, putting it within sensitivity requirements.
by Cassandra R. Hunt.
S.B.
2
Belyaeva, A. I., A. A. Galuza, I. V. Kolenov, V. G. Konovalov, Alla Aleksandrovna Savchenko, and O. A. Skoryk. "Effect of sputtering on the samples of iter-grade tungsten preliminarilly irradiated by tungsten ions: optical investigations." Thesis, Національний науковий центр "Харківський фізико-технічний інститут", 2014. http://repository.kpi.kharkov.ua/handle/KhPI-Press/48176.
Повний текст джерела
3
Morberg, Hampus. "Conceptual Speaker Study." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Maskinteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-25081.
Повний текст джерелаАнотація:
This thesis project is a stand-alone project with the goal to develop an optimized material suited for speaker cabinets, with the focus on acoustic abilities, production possibilities and environmental impact. And to further on design a high performance to price speaker, using the developed material properties and todays technology. The thesis is focused heavily on testing material, starting with research and thereafter creating and testing samples, to continue with find a material combination that would work for a product fit for the market. The final product should fulfill the demands of typical furniture handling, meaning it should be able to be moved around and withstand moderate abuse from daily events. The project results in a functional prototype for evaluation of material and the overall design. The project is based on design methods and design thinking.
4
Ko, Kang-Hoon. "Heat transfer enhancement in a channel with porous baffles." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1519.
Повний текст джерелаАнотація:
An experimental and numerical investigation of heat transfer enhancement in a
three dimensional channel using wall mounted porous baffles was conducted. The
module average heat transfer coefficients were measured in a uniformly heated
rectangular channel with staggered positioned porous baffles. A numerical procedure
was implemented, in conjunction with a commercially available Navier-Stokes solver, to
model the turbulent flow in porous media. The Brinkman-Forchheimer-Extended Darcy
model was used for modeling fluid flow through the porous baffles. Conventional, oneequation,
and two-equation models were used for heat transfer modeling. The accuracy
and characteristics of each model were investigated and discussed. The results were
compared with experimental data.
Baffles were mounted alternatively on the top and bottom walls. Heat transfer
coefficients and pressure loss for periodically fully developed flow and heat transfer
were obtained for different pore densities (10, 20, and 40 pores per inch (PPI)) with two
different baffle heights ( / h h B D = 1/3 and 2/3), and two baffle thicknesses ( / t h B D = 1/3
and 1/12). The Reynolds number (Re) was varied from 20,000 to 50,000. To compare
the effect of foam metal baffles, the data for conventional solid-type baffles was
obtained for ( / t h B D =1/3). The maximum uncertainties associated with the module
Nusselt number and friction factor were 5.8% and 4.3%, respectively. The experimental
procedure was validated by comparing the data for the straight channel without baffles
( / h h B D = 0) with those in the literature.
The use of porous baffles resulted in heat transfer enhancement as high as 300%
compared to heat transfer in straight channels without baffles. However, the heat transfer
enhancement per unit increase in pumping power was less than one for the range of
parameters studied in this work. Correlation equations were developed for the heat
transfer enhancement ratio and the heat transfer enhancement per unit increase in
pumping power in terms of Reynolds number.
The conventional theoretical model, the dispersion conductivity model, and the
modified two-phase model using the local thermal non-equilibrium theory were
considered. The results from each model were compared against the experimental data,
and compared to each other to investigate the efficiency of each model. Also, the
characteristics of each model were discussed.
5
Marshall, Laurie D. "Transducer-baffle interaction." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15821.
Повний текст джерела
6
Bektas, Murat [Verfasser]. "BaFe(1-x)-0.01Al0.01TaxO3-δ: A material for temperature independent resistive and thermoelectric oxygen sensors / Murat Bektas." Düren : Shaker, 2020. http://d-nb.info/1215461763/34.
Повний текст джерела
7
Gullason, Lynda. "Engendering interaction : Inuit-European contact in Frobisher Bay, Baffin Island." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35893.
Повний текст джерелаАнотація:
This thesis seeks to identify the mosaic, rather than the monolithic, nature of culture contact by integrating historical and archaeological sources relating to the concept of gender roles, as they influence response within a contact situation. Specifically, I examine how the Inuit gender system structured artifact patterning in Inuit-European contact situations through the investigation of three Inuit sites in Frobisher Bay, Baffin Island. These date from the 16th, 19th and early 20th centuries and represent a variety of seasonal occupations and dwelling forms.The ethnographic data suggest that Inuit gender relations were egalitarian and complementary. On this basis I hypothesize that European goods and materials were used equally by men and women. Within each gendered set of tasks, European goods and materials were differently used, according to empirically functional criteria such as the nature of the tasks.
Opportunities for and responses to European contact differed depending on the types of tasks in which Inuit women and men engaged and the social roles they played. Seasonality of occupation bears upon the archaeological visibility of gender activities.
Sixteenth-century Elizabethan contact did not alter Nugumiut gender roles, tasks, authority or status but served primarily as a source of raw material, namely wood and iron. Based on the analysis of slotted tools I suggest a refinement to take account of the overlap in blade thickness that occurs for metal and slate, and which depends on the function of the tool. I conclude that there was much more metal use by Thule Inuit than previously believed. However, during Elizabethan contact and shortly afterwards there was actually less metal use by the Nugumiut than in the prehistoric era.
Little archaeological evidence was recovered for 19th-century commercial whaling contact, (suggesting geographic marginality to European influence), or for 19th century Inuit occupation in the area. This is partly because of immigration to Cumberland Sound and because of subsequent structural remodelling of the dwellings by later occupants.
By the early 20th century, the archaeological record showed not only equal use of European material across gender but a near-ubiquitous distribution across most activity classes, even though commercial trapping never replaced traditional subsistence pursuits but only supplemented them.
8
Milligan, David J. "The baffle aperture region of an ion thruster." Thesis, University of Southampton, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.342779.
Повний текст джерела
9
Fu, Yanqing. "Dynamic Emission Baffle Inspired by Horseshoe Bat Noseleaves." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/64906.
Повний текст джерелаАнотація:
The evolution of bats is characterized by a combination of two key innovations - powered flight and biosonar - that are unique among mammals. Bats still outperform engineered systems in both capabilities by a large margin. Bat biosonar stands out for its ability to encode and extract sensory information using various mechanisms such as adaptive beam width control, dynamic sound emission and reception, as well as cognitive processes. Due to the highly integrated and sophisticated design of their active sonar system, bats can survive in complex and dense environments using just a few simple smart acoustic elements. On the sound emission side, significant features that distinguish bats from the current man-made sonar system are the time-variant shapes of the noseleaves. Noseleaves are baffles that surround the nostrils in bats with nasal pulse emission such as horseshoe bats and can undergo non-rigid deformations large enough to affect their acoustic properties significantly. Behavioral studies have shown that these movements are not random byproducts, but are due to specific muscular action. To understand the underlying physical and engineering principles of the dynamic sensing in horseshoe bats, two experimental prototypes ,i.e. intact noseleaf and simplified noseleaf, have been used. We have integrated techniques of data acquisition, instrument control, additive manufacturing, signal processing, airborne acoustics, 3D modeling and image processing to facilitate this research. 3D models of horseshoe bat noseleaves were obtained by tomographic imaging, reconstructed, and modified in the digital domain to meet the needs of additive manufacturing prototype. Nostrils and anterior leaf were abstracted as an elliptical outlet and a concave baffle in the other prototype. As a reference, a circular outlet and a straight baffle designed. A data acquisition and instrument control system has been developed and integrated with transducers to characterize the dynamic emission system acoustically as well as actuators for recreating the dynamics of the horseshoe bat noseleaf. A conical horn and tube waveguide was designed to couple the loudspeaker to the outlet of bat noseleaf and simplified baffles. A pan-tilt was used to characterize the acoustic properties of the deforming prototypes over direction. By using those techniques, the dynamic effect of the noseleaf was reproduced and characterized. It was suggested that the lancet rotation induced both beam-gain and beamwidth changes. Narrow outlet produced an isotropic beampattern and concave baffle had a significant time-variant and frequency-variant effect with just a small displacement. All those results cast light on the possible functions of the biological morphology and provided new thoughts on the engineering device's design.Ph. D.
10
Santos, Nicolau Braga. "Heat transfer in channels with solid and porous baffles." Instituto Tecnológico de Aeronáutica, 2006. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=303.
Повний текст джерелаАнотація:
This work focuses on the study of flow and heat transfer in a parallel plate channel with solid and porous baffles, in both laminar and turbulent regimes by using numerical simulations. The main concern is to validate results by using a unique set of equations (for porous, solid and clear domain) for channels with solid baffles, after that change solid to porous baffles and study the effects on flow and heat transfer. Porous medium is treated as rigid, homogeneous and isotropic. The macroscopic transport equations are written for an elementary representative volume, yielding a set of equation valid for the entire computational domain. These equations are discretized using the control volume method, and the resulting system of algebraic equations is solved by the SIP algorithm utilizing the SIMPLE method for the pressure-velocity coupling. Initially, the laminar flow regime is analyzed, followed by turbulent flow simulations, utilizing both Low and High Reynolds turbulence models. Three different baffles heights were chosen for laminar and turbulent flow, aiming for further comparisons to literature data. Derivations are carried out under the recently established double-decomposition concept. Results show good qualitative agreement with literature data, for both laminar and turbulent cases, and good quantitative agreement with literature data, for laminar and some turbulent results.
11
Schluntz, Alexandra Oakley. "Specular Black Baffle Design Sponsored by Raytheon Missile Systems." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/321936.
Повний текст джерела
12
Thrasher, Patrick Ambrose. "Specular Black Baffle Design Sponsored by Raytheon Missile Systems." Thesis, The University of Arizona, 2014. http://hdl.handle.net/10150/322076.
Повний текст джерела
13
Sakthitharan, Vaithianathaiyer. "Time-resolved measurements of flame propagation over baffle-type obstacles." Thesis, Imperial College London, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338428.
Повний текст джерела
14
Fronk, Thomas Harris. "Fully-coupled fluid-structure analysis of a baffled rectangular orthotropic plate using the boundary element and finite element methods." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-07282008-134729/.
Повний текст джерела
15
Baston, Conrad R. "Preliminary investigation of culvert outlet baffle block geometry and energy dissipation." Morgantown, W. Va. : [West Virginia University Libraries], 2000. http://etd.wvu.edu/templates/showETD.cfm?recnum=1257.
Повний текст джерелаАнотація:
Thesis (M.S.)--West Virginia University, 2000.Title from document title page. Document formatted into pages; contains xii, 140 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical references (p. 137-139).
16
Bennett, Daniel Christian. "The inverse phase suspension polymerisation of acrylamide in an oscillatory baffle reactor." Thesis, University of Strathclyde, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273339.
Повний текст джерела
17
Duan, Yuping Khodadadi J. M. "Effect of a baffle on pseudosteady-state natural convection inside sperical containers." Auburn, Ala., 2007. http://hdl.handle.net/10415/1399.
Повний текст джерела
18
Velikov, S. "Wind tunnel modelling of aerodynamic baffle arrays for aircraft exhaust plume control." Thesis, Cranfield University, 2014. http://dspace.lib.cranfield.ac.uk/handle/1826/9290.
Повний текст джерелаАнотація:
Local air quality is one of the factors constraining the development of airports. In countries of the European Union where new, stricter regulations for emissions of nitrogen oxides (NOx) have been introduced since 2010, the limits of mean annual concentrations are already exceeded at certain ground monitoring locations of large airports. This research project investigates the possibility of abating the aircraft exhaust plume at take-off by placing an array of aerodynamic windbreaks (‘baffles’) in the runway end safety area close to the aircraft starting position. The undertaken experimental investigation comprised sub-scale wind tunnel tests and full-scale field trials with a BAe 146-301 aircraft, performing take-off and landing cycles at Cranfield Airport. The initial wind tunnel experiments investigated the effect of a solid baffle row, placed in the path of a buoyant nozzle jet, on the development of the plume downstream. Using flow visualisation, the positive effect of the baffle row of promoting buoyant rise of the plume away from the ground was demonstrated successfully without the presence of wind tunnel flow. The investigation highlighted the importance of the distance of the baffles relative to the jet source on their effectiveness. In the presence of wind tunnel flow, the baffles caused an increased vertical spread of the plume downstream, but the plume was not observed to separate from the ground. In preparation of the field trials, the spatial arrangement of the baffle array was investigated by means of wind tunnel drag measurements, performed with a skinfriction balance. The experiments focused on key parameters such as the baffle slope angle and row spacing, favouring a configuration of three rows of baffles of increasing height. Based on the wind tunnel measurements, full-scale baffle prototypes were designed and manufactured at Cranfield University and were deployed in the field trials. Lidar and point sampler measurements during the field trials suggested that the plume had risen away from the ground on one occasion when the aircraft was located close to the baffles. A positive effect was shown in terms of reduced concentrations downstream of the baffles. This result was not replicated when the aircraft was further away from the baffles. The subsequent wind tunnel experiments focused on replicating the field trials at 1:200 scale in Cranfield’s Atmospheric Boundary Layer Wind Tunnel. The aircraft was represented at sub scale with a single stationary nozzle while the jet speed and buoyancy were modelled using similarity parameters such as the Froude number and the ratio of ambient and jet density. Mean concentration measurements were performed using a Flame Ionisation Detector method releasing methane as tracer gas. The effect of the baffles was observed to be mainly local in terms of reduced concentrations close the ground due to their sheltering effect. A more prolonged effect was found to be the increase of the plume’s vertical spread resulting in an increase in mean concentrations away from the ground.
19
Velikov, S. "Wind Tunnel Modelling of Aerodynamic Baffle Arrays for Aircraft Exhaust Plume Control." Thesis, Cranfield University, 2015. http://dspace.lib.cranfield.ac.uk/handle/1826/9290.
Повний текст джерелаАнотація:
Local air quality is one of the factors constraining the development of airports. In
countries of the European Union where new, stricter regulations for emissions of
nitrogen oxides (NOx) have been introduced since 2010, the limits of mean annual
concentrations are already exceeded at certain ground monitoring locations of large
airports. This research project investigates the possibility of abating the aircraft exhaust
plume at take-off by placing an array of aerodynamic windbreaks (‘baffles’) in the
runway end safety area close to the aircraft starting position.
The undertaken experimental investigation comprised sub-scale wind tunnel tests
and full-scale field trials with a BAe 146-301 aircraft, performing take-off and landing
cycles at Cranfield Airport. The initial wind tunnel experiments investigated the effect
of a solid baffle row, placed in the path of a buoyant nozzle jet, on the development of
the plume downstream. Using flow visualisation, the positive effect of the baffle row of
promoting buoyant rise of the plume away from the ground was demonstrated
successfully without the presence of wind tunnel flow. The investigation highlighted the
importance of the distance of the baffles relative to the jet source on their effectiveness.
In the presence of wind tunnel flow, the baffles caused an increased vertical spread of
the plume downstream, but the plume was not observed to separate from the ground.
In preparation of the field trials, the spatial arrangement of the baffle array was
investigated by means of wind tunnel drag measurements, performed with a skinfriction
balance. The experiments focused on key parameters such as the baffle slope
angle and row spacing, favouring a configuration of three rows of baffles of increasing
height. Based on the wind tunnel measurements, full-scale baffle prototypes were
designed and manufactured at Cranfield University and were deployed in the field trials.
Lidar and point sampler measurements during the field trials suggested that the
plume had risen away from the ground on one occasion when the aircraft was located
close to the baffles. A positive effect was shown in terms of reduced concentrations
downstream of the baffles. This result was not replicated when the aircraft was further
away from the baffles.
The subsequent wind tunnel experiments focused on replicating the field trials at
1:200 scale in Cranfield’s Atmospheric Boundary Layer Wind Tunnel. The aircraft was
represented at sub scale with a single stationary nozzle while the jet speed and buoyancy
were modelled using similarity parameters such as the Froude number and the ratio of
ambient and jet density. Mean concentration measurements were performed using a
Flame Ionisation Detector method releasing methane as tracer gas. The effect of the
baffles was observed to be mainly local in terms of reduced concentrations close the
ground due to their sheltering effect. A more prolonged effect was found to be the increase of the plume’s vertical spread resulting in an increase in mean concentrations
away from the ground.
20
Leech, Shannon R. "The transport of materials by ice in a subarctic macrotidal environment, Koojesse Inlet, southeast Baffin Island." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq39145.pdf.
Повний текст джерела
21
Li, Jundong. "ANALYTICAL AND BOUNDARY ELEMENT SOLUTIONS OF BULK REACTING LINED DUCTS AND PARALLEL-BAFFLE SILENCERS." UKnowledge, 2017. http://uknowledge.uky.edu/me_etds/96.
Повний текст джерелаАнотація:
Lined silencers of various configurations are used to attenuate the noise from building HVAC equipment, gas turbines, and other machinery. First-mode analytical solutions are presented for sound attenuation along rectangular lined ducts, parallel-baffle silencers, and circular lined ducts. The sound absorptive lining is treated using a bulk property model. The analytical solutions entail solving a nonlinear characteristic equation in the transverse direction after the rigid-wall boundary condition is applied. The solution is compared to the boundary element solution and a local impedance analytical solution for several test cases.
22
Holt, Gavin J. "Experimental Characterization of Baffle Plate Influence on Turbulent and Cavitation Induced Vibrations in Pipe Flow." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2765.
Повний текст джерелаАнотація:
Turbulent and cavitation induced pipe vibration is a large problem in industry often resulting in pipe failures. This thesis provides an experimental investigation on turbulent flow and cavitation induced pipe vibration caused by sharp edged baffle plates. Due to large pressure losses across a baffle plate, cavitation can result. Cavitation can be destructive to pipe flow in the form of induced pipe wall vibration and cavitation inception. Incipient and critical cavitation numbers are design points that are often used in designing baffle plate type geometries. This investigation presents how these design limits vary with the influencing parameters by exploring a range of different baffle plate geometries. The baffle plates explored contained varying hole sizes that ranged from 0.159 cm to 2.54 cm, with the total through area, or openness, of each baffle plate ranging between 11% and 60%. Plate thickness varied from 0.32–0.635 cm. Reynolds numbers ranged from 5 x 10^4 -85 x 104. The results show that the cavitation design limits are function of size scale effects and the loss coefficient only. The results also show that the loss coefficient for a baffle plate varies not only with total through area ratio, but also due with the plate thickness to baffle hole diameter ratio. Pipe wall vibrations were shown to decrease with increased through area ratio and increased thickness to diameter ratios. An investigation was also performed to characterize the attenuation of vibration in the streamwise direction of a baffle plate. It was show that the attenuation was largely effected by the presence of cavitation. Attenuation was shown to be a function of the geometry of the baffle plate. This work resulted in empirical models that can be used for predicting pipe vibration levels, the point of cavitation inception, and the streamwise distance where the attenuation of vibration levels caused by a baffle plate occurs.
23
Mohammadi, Koorosh [Verfasser], and Hans [Akademischer Betreuer] Müller-Steinhagen. "Investigation of the effects of baffle orientation, baffle cut and fluid viscosity on shell side pressure drop and heat transfer coefficient in an e-type shell and tube heat exchanger / Koorosh Mohammadi. Betreuer: Hans Müller-Steinhagen." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2011. http://d-nb.info/1017972672/34.
Повний текст джерела
24
Bujalski, Jakub Michal. "Computational fluid dynamic modelling of stirred reactors : power, baffle stresses, mixing times and semi-batch precipitation." Thesis, University of Birmingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289683.
Повний текст джерелаАнотація:
A commercial CFD (Computational Fluid Dynamics) code CFX (version 4.2 to 4.4) from AEA Technologyl'' has been used to compute the fluid flow, power number, Po, the stresses on baffles, mixing time and a precipitation reaction in a mixing vessel. The impellers investigated were Rushton turbine and 4 or 6 blade 45° pitch blade turbine. The impeller generated flow was modelled primarily using the sliding mesh technique, with additional modelling using Multiple Frames of Reference (MFR) for the mixing time simulations. The Po was estimated from three different methods i.e. specific energy dissipation rate, ET, summation, torque acting on the impeller surfaces, POp(primary power number), and the reaction torque acting on the vessel walls and baffles, POs (the secondary power number). The Po from the summation of ET, was underpredicted as compared with experimental values in all the simulations by over 50%. The investigation of the calculated power numbers for the vessels found that the closest and most consistent values of Po compared to experimental results were obtained from the torque acting on the impeller surfaces, POp. The value of POs was found to be greatly dependent on the sliding mesh simulation parameters and an improvement in the POsprediction could be obtained by using a small time step. A further investigation lead to the computation of the tangential forces and subsequently the axial pressure distribution on the baffles. The baffle pressure distribution depends on the impeller type and its clearance and was better predicted for greater impeller clearances and for the radial flow impellers. The mixing times simulations were performed using a computational method analogous to the experimental method of probe responses. The system was in the high transitional flow regime (Re=8800) and a low Reynolds k-e turbulence model was used in the development of the flow field. The simulations were compared with experimental results (based on decolorisation technique) and to three different mixing time correlations giving mixing times at three different levels of homogenisation (i.e. 90%, 95% and 99%). Worryingly, the simulation results were found to depend on the radial feed position even though the experimental results suggest that it does not. At certain radial position, the simulated mixing time responses accurately predicted the mixing times from the experiments and empirical correlations. CFD based flow visualisation showed that the feed position influenced where the majority of the tracer was initially distributed. The further the radial position was from the axis of the impeller, the more the bulk of the tracer moved towards the low velocity region near the vessel walls, leading to an overestimate of the mixing time. The sliding mesh and MFR simulations of the velocity fields were used for the computation of the mixing time. The results were similar in each case. The precipitation modelling was achieved through the coupling of the CFD hydrodynamics and user defined precipitation model. This approach was able to predict the performance of a semi-batch process involving the precipitation of BaS04 with 270 s addition time. The results (i.e. mean crystal size (d[4,3]) and the particle size distributions) were compared with experimental results for a double feed precipitation reaction for a number of feed configurations and concentration ratios. Overall reasonable trends and agreement have been obtained for the modelled Po, mixing time and baffle stresses. The precipitation model was less successful and was very dependant on the different crystal shape factors used in the simulation model. Further experimental work is required in order to define this parameter accurately, especially as experiments have shown that it varies during the addition time.
25
Duncan-Chamberlin, Katherine V. "The Effect of Baffles and Entrance Ports on the Measured Reflectance of Diffuse and Specular Samples in the Integrating Sphere." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1430151078.
Повний текст джерела
26
Shiroyanagi, Yuko. "Implementation of a high temperature superconducting magnet lead system." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1198177938.
Повний текст джерела
27
Vaigauskaitė, Aistė. "Įvairių tipų dinaminių slopintuvų taikymas netiesinėms sistemoms." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060606_181129-40925.
Повний текст джерелаАнотація:
The application of the dynamical baffles in the mechanical systems, when the sources of stimulation are impossible to abolish, is one of the ways to fight against the harmful vibrations. The model of a dynamic baffle was applied for suppression of oscillations of the nonlinear mechanical systems. With the help of the baffle the system parameters were determined with the smallest possible amplitudes.
28
Tsegay, Awet Eyob. "Underground Stormwater Treatment Performance in Urban Coastal Catchments: Case Study of Baffle Boxes in the City of Tampa." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7372.
Повний текст джерелаАнотація:
In coastal urban regions, underground stormwater treatment units are suitable infrastructure options because they take less space where premium land is expensive. Even then, they should be accessible and ideally small enough to fit into existing stormwater networks. Since 2003, the City of Tampa and Florida’s Department of Transportation (FDOT) have installed 47 baffle boxes into the city’s stormwater pipe networks. Baffle boxes are underground stormwater treatment structures designed to capture sediments and floating debris. Since their deployment, many challenges regarding their practical sediment capturing performance was raised by the city.
The objective of this research was to evaluate the effects of rainfall, land use, and maintenance on the sediment trapping efficiency of the baffle boxes and identify solutions to enhance their performance. This was addressed through site visits, sediment accumulation measurements and analysis of historical and field data. The results of these measurements and analysis were then compared to rainfall intensity, catchment characteristics, size and type of the units. During the preliminary site visits and sediment measurements it was observed that most of the units located in the south of Tampa were inundated by backflows from Tampa Bay. Survey information collected from inspection crew members also showed that resuspension of trapped sediments frequently occurs in these units. Concerning operation and maintenance (O&M), it was indicated that units mounted with screens are costly and difficult to clean-out. Additionally, it was found that 80% of the units have very small trap inlets and lack the baffle structures needed to slow down and settle sediments.
Historical sediment measurements and O&M practices were analyzed to calculate the overall performance of the units. The analysis of the data determined the sediments captured, the resuspension rate, and yearly cost of maintenance for different types of baffle boxes. Rainfall intensity and land use and land cover (LULC) data for each catchment of the units was correlated to the performance of the units. The LULC data used impervious fraction and tree canopy area of the catchments to project sediment and leaf matter accumulation within the units.
This research study found that total daily rainfall intensity is a good predictor of sediment accumulation. Cleanout crews can use this relationship to conduct their work efficiently and to promptly react to occurring rainfall events. Thus, the prediction of sediments accumulated from rainfall events and the coordination of clean-out trucks can optimize O&M practices. It was also determined that large-sized (24-40 in) units and those with three chambers (baffles) perform better at trapping sediments. Thus, installing baffles in units within the large-sized ones can enhance their performance. The study also found that baffle boxes mounted with screens can individually take up to eight hours to cleanup which makes them costly and difficult. This can be detrimental for municipalities to follow up on their O&M practices effectively. Therefore, to alleviate the clean out complexity and reduce maintenance expenditures complementary practices such as bag filters need to be explored and implemented for trials
29
Ståhl, Daniel. "Material Library : A sense of material." Thesis, Tekniska Högskolan, Högskolan i Jönköping, JTH, Maskinteknik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hj:diva-25076.
Повний текст джерелаАнотація:
This day of age when an increasing demands for better and more environmental friendlymaterial is requested. At the same time is also higher demands on the designers todevelop new products for the future. To design new products which express a futuristicfeeling and a “must-have-feeling”. Therefore is there a need to educate better designersand architects for the future a better knowledge for material. Both for existing designersand architects but also for new designers. To encourage learning and discover newmaterial is new tools important, a tool such as a meeting point in which people meet, talkand discover new materials. A meeting place in which a material library has its naturalplace, a place designers, architects and laymen can visit. The great advantages of a material library is the possibility to touch and feel the materialsamples. To invite people to use their senses and learn about materials. This report focus on how to best build and present a material library in the facility of apublic place. But also how to construct a mobile module used as a tool for education.Each scenario has their own dilemma and needs, for example, in the University library atJönköping has criterion for a module that fits into the regular exhibition. To present newand innovative material samples in a manner that reminds of how people search forbooks on the shelves. For the mobile module is focus more towards presenting material samples used in theproduction today. The presentation is more focus on presenting material samples during alecture in which the teacher stands in front of a class and pointing towards the materialand students are allowed to touch and feel the material samples when they have thepossibility to do so. Besides this will the mobile module also work as mobile storagelocation for each department’s material samples.
30
Allen, Jeremy L. "The Effect of Baffle Arrangements on Flow Uniformity in a Manifold for a Unique Solid Oxide Fuel Cell Stack Design." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1320851931.
Повний текст джерела
31
Meadows, Jessica Morris Natasha. "Material sustainability /." Click here to view, 2009. http://digitalcommons.calpoly.edu/arcesp/1/.
Повний текст джерела
32
Fahlén, Sara, and Ljungqvist Josefa Nädele. "Textila material." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-16842.
Повний текст джерелаАнотація:
Under ett samarbete med underklädesbutiken Bornevings har information om textila materialtagits fram. Butiken erbjuder alltid god service när det gäller utprovning av plagg men saknarbaskunskaper om textila material och hur de tillverkas. Textil informationen har tagits framför att underlätta detta problem. Kunskapsbristen kommer nu att eliminerats så personalen kanerbjuda den bästa servicen.För att få reda på hur informationen på bästa sätt skulle redovisas för butiken studeradespedagogik. Inlärning fungerar olika för alla, vissa tar till sig bilder medan andra lättare kanregistrera text. Lärande äger rum mellan minst två personer. Det ena kan vara i form av enskrift, till exempel en bok. För att kunna ställa sig kritisk till ämnen krävs först kunskap. Allkunskap är positiv för individen och ligger till grund för ens förutsättningar i livet.För att personalen hela tiden ska kunna gå tillbaka till den information som tagits fram tillbutiken har informationen valts att redovisas i ett tryckt format. Resultatet blev en handbok.Den innehåller information om materialen som varorna i Bornevings butik består av. Materialsom tas upp är bomull, polyester, polyamid, elastan, modal, viskos, lyocell, ull och silke.I handboken beskrivs det grundläggande om hur ett material blir till, alltifrån fiberstadiettill tillverkningsprocesser såsom väv och trikå, samt hur de olika metoderna kan påverkaslutresultatet.Handboken gavs ut till en urvalsgrupp av olika ålder, kön och yrke. Det för att kontrolleratextens nivå så att den var enkel att ta in och att fackord eliminerats. Allt för att skapa en såenkel och informativ text som möjligt.During collaboration with the underwear store Borneving has information on textile materialsbeen developed. The store always offers excellent service when it comes to try out the best fitof garments but lacks basic knowledge of textile materials and how they are made. A textilehandbook has been produced to prevent this problem. The lack of knowledge will now beeliminated so the staff can provide the best service.To find out how the information in the best way would be presented for the store werepedagogy studied. Learning works differently for everyone. Some will remember pictureswhile others can more easily register text. Learning takes place between at least two people.One person may be in the form of a book. In order to be critical to subjects it requiresknowledge. All knowledge is positive for the individual and forms the basis of one'sopportunities in life.In order so the staff all the time can go back to the information generated to the shop theinformation has been selected to be presented in a printed format. The result of this was ahandbook. It includes information about materials to which the goods in Bornevings shopconsists of. Materials covered are cotton, polyester, polyamide, elastane, modal, viscose,lyocell, wool and silk. The handbook describes the basic of how a material is created, fromfiber through to manufacturing processes such as woven and knitted, and how the differentmethods can affect the final result.The handbook was distributed to a select group of different age, gender and occupation. Thiswas to control the text's level so it was easy to take in and that technical terms are eliminated.All to create a simple and informative handbook as possible.Program: Textil produktutveckling med entreprenörs- och affärsinriktning
33
Murphy, John A. "Material accomodation." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/53239.
Повний текст джерелаАнотація:
Architectural decision making, in terms of a formal design methodology, must be based on a sincere understanding and sympathetic employment of architectural building materials. These materials, each with their own inherent tectonics, come together to formulate a network of inter-dependent relationships categorized as material accommodation. Material accommodation consists of three specific areas. First, as indicators of formal issues, secondly, they will communicate structural awareness, and finally from a syntactic dimension.Master of Architecture
34
Wetterström, Vendela. "Social Material." Thesis, Konstfack, Grafisk design & illustration, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-7998.
Повний текст джерела
35
Minchin, Carol E. "Material Origins." PDXScholar, 1996. https://pdxscholar.library.pdx.edu/open_access_etds/5164.
Повний текст джерелаАнотація:
The intent of this thesis project was to use sculpture as a means of investigation for exploring the structural uses of Masonite, and to understand how those uses affect the nature of my work. The transformation of this material into form becomes the a process that is adjusted and refined until a formal solution is found. The tension, texture, scale, and form of the work contribute to a dialogue that results in sculptures that reference the human body and the growth of plants.
36
Medina, Menares Sebastían, Espinoza Francisco Higinio Ruiz, and Rojas Daniel Sanhueza. "Material Pipol." Tesis, Universidad de Chile, 2009. http://repositorio.uchile.cl/handle/2250/146309.
Повний текст джерелаАнотація:
Memoria audiovisual para optar al Título Profesional de Periodista"En la primera visita de Madonna al país, Eduardo Espinoza, presidente del fan club oficial Madonna Chile, quiere estar lo más preparado posible para recibir a su ídola. Su amor por ella es tan grande, que durante meses prepara las actividades que rodearán el evento, pero las dificultades surgirán cuando los fanáticos prefieran preocuparse por su propio bien, antes que por la comunidad completa”.
37
Granger, Danielle Ray. "Material Distinctions." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/98557.
Повний текст джерелаАнотація:
The object of this thesis is a modestly scaled house at Smith Mountain Lake. The objective of this thesis is to please the senses through material composition. We gain knowledge and sensible understanding of our world through physical interaction and direct sensory experience. Through touching, smelling, listening, and observing we form and guide our choices. These experiences enrich the designer's knowledge of material properties and thus the proper use of materials.
The primary focus of this study seeks to understand the physical properties of materials in relation to a site and to each other. Following, it attempts to transform these materials into elements of architecture, as the functional components of a building. Forms derive their unique qualities from these materials; qualities that enrich our consciousness, evoke sensible memories, and fulfill expectations. Chosen for their qualities as well as their perceptions, brick and wood, present a dynamic dialogue about mass in volume.The story of this house is told in relation to how the brick responds to the primary structure and how it orchestrates architectural elements within the whole.
The dichotomy between these two materials lends this study to a larger exploration of joinery. The internal joining of wood to wood, or tectonic joining, produces a different expression than the joining of different materials. Wood to brick, for instance produces the legible differentiation of the architectural elements within the house. The arrangement of these materials articulates structure as well as spatial distinctions within the whole. Where volumes detach, glass bridges these materials as its attributes blend the differentiation between an interior and exterior condition. Articulating how these materials meet addresses essential architectural questions of knowledge, thought, and order as well as ephemeral pleasures. To enjoy the physical experience, as it is embraced by all of the senses, is the final goal and desire of this thesis.Master of Architecture
This quest began by trying to treat one side of a constructed line independently from the other side. Formal distinctions were made, and then later material distinctions in order to treat a building's interior and exterior independently. This thesis study treats the structure independently from the envelope, while creating spatial distinctions within the house through material decisions. Brick and wood were chosen for their contrasting properties, both physically and perceptually. The Brick, with its telluric, of the earth presence, has an obligation to the site, weather, and time. The wood on the other hand, with its tectonic nature, has an obligation to the human touch. The structure, which serves as protection from the elements, its pulled inside to live with the humans as heavy timber posts. The brick is then left to the essential elements of the house, to one day stand as ruins. Namely, the entrance, the hearth, the base, and parts of the envelope, The architectural questions are then asked through material composition and elemental joints.
38
Hakala, Allison Lynn. "Material homonyms." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1327598023.
Повний текст джерела
39
KRIVANKA, SARAH M. "SENSITIVE MATERIAL." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1179208847.
Повний текст джерела
40
Bailey, Teri. "Material Bodies." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555451326557221.
Повний текст джерела
41
Jordan, Anne. "Material Meaning." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2789.
Повний текст джерелаАнотація:
The synthesis of old and new, analog and digital, and hand- and computer-based methods provides designers with an opportunity to work beyond the constraints of the computer and take advantage of the aesthetic effects that actual materials bring to visual communication. Designers who choose to actively participate in their process – bringing the aesthetic effects of working materially into the realm of the digital – will likely learn to reject an approach that relies too heavily on passive digital tools. Active participation in the design process can extend our creative vocabulary and humanize visual communication.
42
Blom, Ulrika. "Hållbara material : fossilbaserade material byts mot hållbar (biobaserad) textil." Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-22059.
Повний текст джерелаАнотація:
Textil- och klädtillverkning är en tungt miljöbelastande bransch. För att ändra på det och få textilindustrin i en riktning mot en hållbar utveckling behöver CO2-utsläpp avsevärt minskas, vattenförbrukningen drastiskt sjunka och risken för spridning av mikroplaster i naturen minimeras. De tre vanligaste textila fibrerna på marknaden, polyester, bomull och polyamid, orsakar stora utsläpp av CO2 och förbrukar enorma mängder vatten. Den här rapporten söker finna svar på vilka textila material som kan uppfylla kraven på hållbarhet och om det finns miljövänliga material med likvärdig slitstyrka som hos de tre största fiberslagen. Med hjälp av en litteraturstudie, ett klassificeringsverktyg och ett antal tester på fysiska prover har materialen ovan tillsammans med lyocell och PLA undersökts och studerats. Den ekologiska och den fysiska hållbarheten har jämförts och värderats. Resultatet av studierna ger inga entydiga svar på frågorna. PLA verkar lovande, men är omgiven av en osäkerhet. Under tiden studien har pågått finns inga tecken på försvagning av PLA-tyget, men kommer det hålla för hundra tvättar? Lyocell är miljömässigt hållbart och slitstarkt i teorin, men smulades tidigt sönder i nötningstestet. Lyocelltyget var gjort av tunt stapelfibergarn. Skulle det varit starkare om det varit tillverkat av filamentgarn? Återvunnen polyester kontra jungfrulig polyester ger ingen stor miljövinst. Däremot ger återvunnen polyamid och ekologisk bomull stora miljömässiga förtjänster. Lyocell, PLA, ekologisk bomull och återvunnen polyamid skulle kunna vara ekologiskt och fysiskt hållbara material.Textiles and apparel manufacturing is a heavily polluting industry. To change that and get the textile industry in the direction of sustainable development, following must be done. Emissions of CO2 need to be considerably reduced, water consumption must drastically decline and the risk of spreading microplastics in nature have to be minimized. The three most common textile fibres on the market, polyester, cotton and polyamide, causing large emissions of CO2 and consumes huge amounts of water. This report seeks to find the textile materials that can meet the requirements of sustainability and eco-friendly materials of equivalent strength as in the three largest fibers like above. With the help of a literature review, a classification tool and a number of tests on physical samples have the materials above along with lyocell and PLA been examined and studied. The ecological sustainability and physical durability has been compared and measured. The results of the studies provides no clear-cut answers to the questions. The PLA seems promising, but are surrounded by uncertainty. In the meantime, the study has been going on, there are no signs of weakening of PLA-fabric, but will it keep for one hundred washes? Lyocell is environmentally sustainable and durable in the theory, but got an early break in the abrasion test. The lyocell fabric were made of thin yarn of staple fibers. Would it have been stronger if it had been made of filament yarn? Recycled polyester versus virgin polyester gives no great environmental benefits. However, recycled polyamide and organic cotton get large environmental gains. Lyocell, PLA, organic cotton and recycled polyamide could be environmentally and physically durable materials.
43
Thompson, Andrew S. "Experimental Characterization of Flow Induced Vibration in Turbulent Pipe Flow." BYU ScholarsArchive, 2009. https://scholarsarchive.byu.edu/etd/1906.
Повний текст джерелаАнотація:
This thesis presents results of an experimental investigation that characterizes the wall vibration of a pipe with turbulent flow passing through it. Specifically, experiments were conducted using a water flow loop to address three general phenomena. The topics of investigation were: 1) How does the pipe wall vibration depend on the average flow speed, pipe diameter, and pipe thickness for an unsupported pipe? 2) How does the behavior change if the pipe is clamp supported at various clamping lengths? 3) What influence does turbulence generation caused by holed baffle plates exert on the pipe response? A single pipe material (PVC) was used with a range of internal diameters from 5.08 cm to 10.16 cm and diameter to thickness ratios ranging from 8.90 to 16.94. The average flow speed that the experiments were conducted at ranged from 0 to 11.5 m/s. Pipe vibrations were characterized by accelerometers mounted on the pipe wall at several locations along the pipe length. Rms values of the pipe wall acceleration and velocity time series were measured at various flow speeds. Power spectral densities of the accelerometer data were computed and analyzed. Concurrent wall pressure fluctuation measurements were also obtained. The results show that for a fully developed turbulent flow, the rms of the wall pressure fluctuations is proportional to the rms of the wall acceleration and each scale nominally as the square of the average fluid velocity. Also, the rms of the pipe wall acceleration increases with decreasing pipe wall thickness. When changes were made in the pipe support length, it was observed that, in general, pipe support length exercises little influence on the pipe wall acceleration. The influence of pipe support length on the pipe wall velocity is much more pronounced. A non-dimensional parameter describing the pipe wall acceleration is defined and its dependence on relevant independent non-dimensional parameters is presented. Turbulence was induced using baffle plates with various sizes (2.54 cm to 0.159 cm) and numbers of holes drilled through them to provide a constant through area of 35.48 cm2 for each plate. Cavitation exists at high speeds for the largest holed baffle plates and this significantly increases the rms of the pipe wall acceleration. As the baffle plate hole size decreases, vibration levels were observed to return to levels that were observed when no baffle plate was employed. Power spectral densities of the accelerometer data from each baffle plate scenario were also computed and analyzed.
44
Zeng, Jiani. "Expand material presence to material experience with volumetric thinking : voxel based multi-material printing in designing objects." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/129844.
Повний текст джерелаАнотація:
Thesis: S.M. in Engineering and Management, Massachusetts Institute of Technology, System Design and Management Program, February, 2020Cataloged from student-submitted version of thesis.
Includes bibliographical references (pages 68-70).
Material serves as the first touchpoint between an object and a person. In current product development, material together with color and finishing is regarded as a separate entity from the form and function design. Every material needs to be paired with a series of optimal manufacturing processes for the desired effect. In many cases, this is handled with material design specialists. People perceive a material primarily by its surface: chromatic, tactile, and decorative identity it displays or the temperature and hardness when touching it. Typically, this material surface can be viewed as a two-dimensional entity that reveals limited-expression and information to be delivered via human intervention. In this thesis, we propose to get away from surface obsession in object and industrial design, by adding another dimension to the material interface. By embedding information into three-dimensional matter, we introduce volumetric material: a new material organization that responds directly to the user intervention or the environment. With multi-material 3D printing, we envision a future in product development where the design of surface detail, texture, reflexivity can finally be merged with the overall product composition from the beginning of the design process. With voxel printing capability, we designed and tested material interface with depth and explored volumetric behavior that is both visually and functionally meaningful to the user, and discussed the results.
by Jiani Zeng.
S.M. in Engineering and Management
S.M.inEngineeringandManagement Massachusetts Institute of Technology, System Design and Management Program
45
Dan-Jumbo, F. G. "Material and structural properties of a novel Aer-Tech material." Thesis, Coventry University, 2015. http://curve.coventry.ac.uk/open/items/699ca3a1-deec-4549-b907-0e06bcdad83f/1.
Повний текст джерелаАнотація:
This study critically investigates the material and structural behaviour of Aer-Tech material. Aer- Tech material is composed of 10% by volume of foam mechanically entrapped in a plastic mortar. The research study showed that the density of the material mix controls all other properties such as fresh state properties, mechanical properties, functional properties and acoustic properties. Appreciably, the research had confirmed that Aer-Tech material despite being classified as a light weight material had given high compressive strength of about 33.91N/mm2. The compressive strength characteristics of Aer-Tech material make the material a potential cost effective construction material, comparable to conventional concrete. The material also showed through this study that it is a structural effective material with its singly reinforced beam giving ultimate moment of about 38.7KN. In addition, the Aer-Tech material is seen as a very good ductile material since, the singly reinforced beam in tension showed visible signs of diagonal vertical cracks long before impending rapture. Consequently, the SEM test and the neural network model predictions, carried out had showed how billions of closely tight air cells are evenly distributed within the Aer-Tech void system as well as the close prediction of NN model for compressive strength and density are same with the experimental results of compressive strength and density. The result shows that the Aer-Tech NN-model can simulate inputs data and predicts their corresponding output data.
46
Johansson, Simon. "Creating Digital Photorealistic Material Renders by Observing Physical Material Properties." Thesis, Högskolan i Gävle, Avdelningen för Industriell utveckling, IT och Samhällsbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-16943.
Повний текст джерелаАнотація:
When creating materials in computer graphics, the most common method is to estimate the properties based on intuition. This seems like a flawed approach, seeing as a big part of the industry has already moved to a physically based workflow. A better method would be to observe real material properties, and use that data in the application. This research delves into the art of material creation by first explaining the theory behind the properties of materials through a literature review. The review also reveals techniques that separate and visually presents these properties to artists, giving them a better understanding of how a material behaves. Through action research, an empirical study then presents a workflow for creating photorealistic renders using data collected with these techniques. While the techniques still require subjective decisions when recreating the materials, they do help artists create more accurate renderings with less guesswork.
47
Binois, Remy. "Etude de l'efficacité des silencieux à baffles parallèles et conception de solutions optimisées en basses fréquences." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066523.
Повний текст джерелаАнотація:
Les silencieux à baffles parallèles sont largement utilisés dans les systèmes de chauffage, ventilation et climatisation (CVC) pour réduire le bruit généré par les sources aérauliques. Ces silencieux sont composés d'un certain nombre de baffles insérés dans un conduit de section rectangulaire. Chaque baffle est constitué d'un cadre métallique garni d'un matériau absorbant. Ce travail de thèse vise à analyser l'efficacité acoustique de ces silencieux afin d'en améliorer les performances en basses fréquences. Dans un premier temps, un modèle de propagation bidimensionnel à ``couches'' est développé afin de prédire les pertes par transmission pour une large variété de ce type de silencieux. Ce modèle multimodal repose principalement sur le calcul des modes acoustiques pour la pression moyenne dans chaque couche et a pour avantage de simplifier grandement la procédure de raccordement modal à l'interface entre deux domaines successifs. C'est un modèle facilement implémentable et approprié à des procédures d'optimisation de par sa rapidité et sa facilité de mise en données. Il a été validé expérimentalement lors de deux campagnes de mesure à des échelles réduite et réelle. Dans un second temps, le modèle développé est utilisé pour appréhender différentes pistes d'amélioration en basses fréquences et concevoir des solutions optimisées. Des premières pistes sont examinées dans le cas de silencieux standards concernant l'influence du nombre de baffles, de la symétrie et de la périodicité du silencieux sur le couplage modal et les performances acoustiques. Les autres pistes d'amélioration ainsi que les solutions optimisées ne figurent pas dans cette version pour des raisons de confidentialitéBaffle-type silencers are widely used in the heating, ventilation and air conditioning (HVAC) systems of buildings to reduce noise being emitted from air-moving devices such as fans and air conditioners. These silencers generally consist of several baffles inserted in a duct with a rectangular cross section. Each baffle is made of sound absorbing material such as rockwool or glasswool. Usually, a metallic fairing is also placed at each end of the baffle. This thesis aims to analyze the effectiveness of these acoustic silencers to improve performance at low frequencies. First, a two-dimensional multimodal model is developed to predict the transmission loss for a wide variety of this type of silencer. The numerical model relies mainly on the computation of approximate acoustic modes for the mean pressure in each layer corresponding either to the airway or the baffle. The method offers the advantage that it greatly simplifies the mode matching procedure at the junction between successive domains and it can be used to tackle relatively complex geometrical configurations with the possibility of taking into account the presence of resistive screens between the porous baffle and the air domain. It is also an easy-to-implement and relatively inexpensive model suitable for optimization purposes. It has been experimentally validated in two measurement campaigns at reduced and actual scales. In a second step, the developed model is used to investigate different ways of improving performance at low frequencies. Suggested improvements are discussed in the case of standard silencers regarding the influence of the number of baffles, symmetry and periodicity of the silencer on the modal coupling and acoustic performance. For confidentiality reasons, other suggested improvements and optimized solutions are not included in this version
48
Ng, Chun-yuen Ronald, and 伍俊源. "Building Material Centre." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1996. http://hub.hku.hk/bib/B31983583.
Повний текст джерела
49
Ek, Kristofer. "Additivt tillverkat material." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-152230.
Повний текст джерелаАнотація:
SammanfattningDet här projektet behandlar området Additiv Tillverkning (AM) för metalliska material och undersöker om det är lämpligt att använda vid produktion inom flygindustrin. AM är en relativt ny tillverkningsmetod där föremål byggs upp lager för lager direkt ifrån en datormodell. Teknikområdet tillåter i många fall större konstruktionsfriheter som möjliggör tillverkning av mer viktoptimerade och funktionella artiklar. Andra fördelar är materialbesparing och kortare ledtider vilket har ett stort ekonomiskt värde.En omfattande litteraturstudie har gjorts för att utvärdera alla tekniker som finns på marknaden och karakterisera vad som skiljer de olika processerna. Även maskiners prestanda och kvalité på tillverkat material utvärderas, och för varje teknik listas möjligheter och begränsningar. Teknikerna delas grovt upp i pulverbäddsprocesser och material deposition-processer. Pulverbäddsteknikerna tillåter större friheter i konstruktion, medan material deposition-processerna tillåter tillverkning av större artiklar. Den vanligaste energikällan är laser som ger ett starkare men mer sprött material än de alternativa energikällorna elektronstråle och ljusbåge.Två specifika tekniker har valts ut för att undersöka närmare i detta projekt. Electron Beam Melting (EBM) från Arcam och Wire fed plasma arc direct metal deposition från Norsk Titanium (NTiC). EBM är en pulverbäddsprocess som kan tillverka färdiga artiklar i begränsad storlek då låga krav ställs på toleranser och ytfinhet. NTiC använder en material deposition-process med en ljusbåge för att smälta ner trådmaterial till en nära färdig artikel. Den senare metoden är mycket snabb och kan tillverka stora artiklar, men måste maskinbearbetas till slutgiltig form. En materialundersökning har genomförts där Ti6Al4V-material från båda teknikerna har undersökts i mikroskop och testats för hårdhet. För EBM-material har även ytfinhet och svetsbarhet undersökts då begränsad byggvolym i många fall kräver fogning. Materialen har egenskaper bättre än gjutet material med avseende på styrka och duktilitet, men inte lika bra som valsat material. Provning visar att skillnaden på mekaniska egenskaper i olika riktningar är liten även fast materialet har en inhomogen makrostruktur med kolumnära korn i byggriktningen. EBM ger en finare mikrostruktur och ett starkare material och, tillsammans med de ökade konstruktionsfriheterna, så är det den tekniken som är bäst lämpad för flygplansartiklar då svetsbarheten är god och det finns möjlighet att bearbeta ytan till slutgiltigt krav.Nyckelord: Additiv Tillverkning, Flygteknik, TitanAbstractThis project treats Additive Manufacturing (AM) for metallic material and the question if it is suitable to be used in the aeronautics industry. AM is a relatively new production method where objects are built up layer by layer from a computer model. The art of AM allows in many cases more design freedoms that enables production of more weight optimized and functional articles. Other advantages are material savings and shorter lead times which have a large economic value.An extensive literature study has been made to evaluate all techniques on the market and characterize what separates the different processes. Also machine performance and material quality is evaluated, and advantages and disadvantages are listed for each technique. The techniques are widely separated in powder bed processes and material deposition processes. The powder bed techniques allow more design freedom while the material deposition techniques allow production of large articles. The most common energy source is laser that gives a harder and more brittle material than the alternative energy sources electron beam and electric arc.Two specific techniques have been selected to investigate further in this project. Electron Beam Melting (EBM) from Arcam and Wire fed plasma arc direct metal deposition from Norsk Titanium (NTiC). EBM is a powder bed process that can manufacture finished articles in limited size when no requirements are set on tolerances and surface roughness. NTiC uses a material deposition process with electric arc to melt wire material to a near-net shape. The latter method is very fast and can produce large articles, but have to be machined to finished shape. A material investigation have been made where Ti6Al4V-material from both techniques have been investigated in microscope and tested for hardness. For the EBM-material have also surface roughness and weldability been investigated since the limited building volume often requires welding. The materials have mechanical properties better than cast material with respect to strength and ductility, but not as good as wrought material. Test results show that the difference in mechanical properties in different directions is small, even though the material has an inhomogeneous macrostructure with columnar grains in the building direction. The EBM-material has a finer microstructure and a stronger material and, in combination with improved design freedom, this technique is most suitable for aerospace articles when the weldability is good and it is possible to surface work where requirements of the surface roughness are set.Keywords: Additive Manufacturing, Aeronautics, Titanium
50
Ek, Kristofer. "Additive Manufactured Material." Thesis, KTH, Maskinkonstruktion (Inst.), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-156887.
Повний текст джерелаАнотація:
This project treats Additive Manufacturing (AM) for metallic material and the question if it is suitable to be used in the aeronautics industry. AM is a relatively new production method where objects are built up layer by layer from a computer model. The art of AM allows in many cases more design freedoms that enables production of more weight optimized and functional articles. Other advantages are material savings and shorter lead times which have a large economic value. An extensive literature study has been made to evaluate all techniques on the market and characterize what separates the different processes. Also machine performance and material quality is evaluated, and advantages and disadvantages are listed for each technique. The techniques are widely separated in powder bed processes and material deposition processes. The powder bed techniques allow more design freedom while the material deposition techniques allow production of large articles. The most common energy source is laser that gives a harder and more brittle material than the alternative energy sources electron beam and electric arc. Two specific techniques have been selected to investigate further in this project. Electron Beam Melting (EBM) from Arcam and Wire fed plasma arc direct metal deposition from Norsk Titanium (NTiC). EBM is a powder bed process that can manufacture finished articles in limited size when no requirements are set on tolerances and surface roughness. NTiC uses a material deposition process with electric arc to melt wire material to a near-net shape. The latter method is very fast and can produce large articles, but have to be machined to finished shape. A material investigation have been made where Ti6Al4V-material from both techniques have been investigated in microscope and tested for hardness. For the EBM-material have also surface roughness and weldability been investigated since the limited building volume often requires welding. The materials have mechanical properties better than cast material with respect to strength and ductility, but not as good as wrought material. Test results show that the difference in mechanical properties in different directions is small, even though the material has an inhomogeneous macrostructure with columnar grains in the building direction. The EBM-material has a finer microstructure and a stronger material and, in combination with improved design freedom, this technique is most suitable for aerospace articles when the weldability is good and it is possible to surface work where requirements of the surface roughness are set. Keywords: Additive Manufacturing, Aeronautics, TitaniumDet här projektet behandlar området Additiv Tillverkning (AM) för metalliska material och undersöker om det är lämpligt att använda vid produktion inom flygindustrin. AM är en relativt ny tillverkningsmetod där föremål byggs upp lager för lager direkt ifrån en datormodell. Teknikområdet tillåter i många fall större konstruktionsfriheter som möjliggör tillverkning av mer viktoptimerade och funktionella artiklar. Andra fördelar är materialbesparing och kortare ledtider vilket har ett stort ekonomiskt värde. En omfattande litteraturstudie har gjorts för att utvärdera alla tekniker som finns på marknaden och karakterisera vad som skiljer de olika processerna. Även maskiners prestanda och kvalité på tillverkat material utvärderas, och för varje teknik listas möjligheter och begränsningar. Teknikerna delas grovt upp i pulverbäddsprocesser och material deposition-processer. Pulverbäddsteknikerna tillåter större friheter i konstruktion, medan material deposition-processerna tillåter tillverkning av större artiklar. Den vanligaste energikällan är laser som ger ett starkare men mer sprött material än de alternativa energikällorna elektronstråle och ljusbåge. Två specifika tekniker har valts ut för att undersöka närmare i detta projekt. Electron Beam Melting (EBM) från Arcam och Wire fed plasma arc direct metal deposition från Norsk Titanium (NTiC). EBM är en pulverbäddsprocess som kan tillverka färdiga artiklar i begränsad storlek då låga krav ställs på toleranser och ytfinhet. NTiC använder en material deposition-process med en ljusbåge för att smälta ner trådmaterial till en nära färdig artikel. Den senare metoden är mycket snabb och kan tillverka stora artiklar, men måste maskinbearbetas till slutgiltig form. En materialundersökning har genomförts där Ti6Al4V-material från båda teknikerna har undersökts i mikroskop och testats för hårdhet. För EBM-material har även ytfinhet och svetsbarhet undersökts då begränsad byggvolym i många fall kräver fogning. Materialen har egenskaper bättre än gjutet material med avseende på styrka och duktilitet, men inte lika bra som valsat material. Provning visar att skillnaden på mekaniska egenskaper i olika riktningar är liten även fast materialet har en inhomogen makrostruktur med kolumnära korn i byggriktningen. EBM ger en finare mikrostruktur och ett starkare material och, tillsammans med de ökade konstruktionsfriheterna, så är det den tekniken som är bäst lämpad för flygplansartiklar då svetsbarheten är god och det finns möjlighet att bearbeta ytan till slutgiltigt krav. Nyckelord: Additiv Tillverkning, Flygteknik, Titan