Dissertations / Theses on the topic 'Mechanical noise'
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Mow-Lowry, Conor. "Opto-mechanical noise cancellation." View electronic text, 2002. http://eprints.anu.edu.au/documents/disk0/00/00/07/65/index.html.
Full textAvailable via the Australian National University Library Electronic Pre and Post Print Repository. Title from title screen (viewed Mar. 28, 2003). "A thesis submitted for the degree of Bachelor of Science with Honours in physics at the Australian National University" "November 2002" Bibliography: p. 73-75.
Copley-Woods, Djuna S. (Djuna Sunlight) 1977. "Aircraft interior acoustic noise control." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9330.
Full textIncludes bibliographical references (p. 45).
An experimental study was perfonned to determine which materials are best suited for internal aircraft noise reduction. An impedance tube with dimensions of a scaled aircraft was constructed and evaluated, and eleven materials were tested and compared based on their noise reduction properties, weight, and thickness. Polyvinylidene Fluoride was tested for use in active noise control for a large space.
by Djuna S. Copley-Woods.
S.B.
Qiu, Jin 1974. "Modeling of plate impact dynamics and noise." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80514.
Full textLouie, Lisa Lai Yee. "Active control of pipe-borne pump noise." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/13267.
Full textMahmud, Akib. "Digital Compensation of Phase Noise Caused by Mechanical Vibrations." Thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-387826.
Full textZheng, Haosheng, and Kaichun Zhang. "Noise Analysis of Computer Chassis and Secondary Sound Source Noise Reduction." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-18547.
Full textChiasson, Leo E. Jr. "Radiated noise from a three dimensional truss." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36058.
Full textIncludes bibliographical references (leaves 83-84).
by Leo E. Chiasson, Jr.
M.S.
Ingemanson, Megan Lynn. "Experimental Characterization of Wind Turbine Blade Aerodynamic Noise." Thesis, University of California, Davis, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=1539643.
Full textWind turbine noise at low frequencies less than 300Hz is not only annoying to humans but has been proven to cause serious health issues. Additionally, animals are severely affected by wind turbines because a small increase in ambient noise (as is produced by wind turbines) significantly reduces their listening ability. In an attempt to better understand and characterize the aerodynamic noise of wind turbine blades, experimental testing was completed on PowerWorks 100kW and GudCraft WG700 blade specimens in the University of California, Davis Transportation Noise Control Center's anechoic chamber. Experimental testing and data analysis proved approximately 4.0dB to 6.0dB was produced due to the blades' geometric design for both blade specimens at low frequencies. This noise was maximized at the blades' leading edge along the central portion of the blades' radius. Theoretical prediction models have been used to determine that, for typical wind speeds and low frequencies, noise generated due to the tip passing frequency is clearly predominant.
Hong, Seung Hyuck. "Active noise control of supersonic impinging jet using pulsed microjets." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/46637.
Full textIncludes bibliographical references (leaves 111-113).
This thesis concerns an active noise control of supersonic impinging jet flow using unsteady microjet injection. Supersonic impinging jet involves several problems such as lift loss, ground erosion, significant noise pollution, and sonic fatigue, all of which are dominated by impinging tones mainly caused by well-known phenomenon, the feed back loop. The main goal of this study is to achieve uniform and consistent noise reduction in the entire range of jet operating condition, by means of intercepting this feed back loop. Experimental investigations on ideally expanded Mach number 1.5, supersonic impinging jet flow were carried out at the scaled supersonic experimental facility. The actuator used for active control is composed of pulsed microjets, utilizing a fraction of mass flow rate needed with steady microjets. Two means of producing pulsed microjet were introduced; one with a rotating cap, pulsing at 16 - 100Hz, and the other developed based on the principle of Hartmann tube, pulsing at 4.4 - 6.1kHz, referred to as high frequency actuator. Control parameters related to pulsed microjet injection with rotating cap were varied to evaluate their effects on suppression of impinging tones, whereas the effect of high frequency actuator is shown only as an initial step and needs further investigation in the future. For pulsed microjet with rotating cap, mass flow rate, directly proportional to the supply pressure of microjet, is found to be the most important parameter amongst all and saturated supply pressures for steady and pulsed microjet are demonstrated. It is demonstrated that pulsed microjet gives more noise reduction than steady microjet with the same mass flow rate, at certain range of supply pressure, and also that pulsed microjet could be as effective on suppression of impinging tones as steady microjet with less mass flow rate. In addition, the effect of pulsed microjet on hot temperature impinging jet was examined since the jet is much hotter than ambient air in reality. The concept of extremum control strategy is introduced to more efficiently find an optimal pulsing condition for uniform and consistent noise reduction.
by Seung Hyuck Hong.
S.M.
Oppenheimer, Charles Hugh. "Impact-induced noise and vibration in machine systems for design." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/12614.
Full textRagaller, Paul Aaron. "The reduction of supersonic jet noise using pulsed microjet injection." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/42990.
Full textIncludes bibliographical references (leaf 99).
This thesis is concerned with the active control of supersonic jet noise using pulsed microjet injection at the nozzle exit. Experimental investigations were carried out using this control method on an ideally expanded Mach 1.8 jet operating at 900, 1300 and 1700'F. Six Bosch fuel injectors were modified and mounted on a toroidal manifold around a Mach 1.8 nozzle. Noise data were collected from the jet at baseline condition, which refers to the uncontrolled case. The injectors were fired at pressures of 400 and 800 psig, using water, at frequencies of 1, 5 and 10 Hz and at duty cycles of 50 and 75%. For comparison, acoustic data were also collected from the jet while the microjets were injecting steadily at a constant pressure. The results led to the following two conclusions: for injection at a given mass flow rate, noise reductions are higher with pulsed injection compared to the steady case, and for injection at a given pressure, the amount of noise reduction increases with duty cycle. In particular, for pulsing at a 50% duty cycle, pulsing achieves comparable noise reduction as compared to steady injection at all of the temperatures tested while using only 66% of the mass flow rate. The most dramatic result was achieved at 17000F for pulsing at a 75% duty cycle with an injection pressure of 800 psig. In this case, pulsing achieves 317% of the noise reduction as compared to steady injection (corresponding to 2.6 and 0.8 dB respectively) while using a comparable amount of water. Similar results were obtained at lower temperatures as well. At all operating points it was found that less water is used with pulsing to achieve a given noise reduction, and is realized at the cost of a higher injection pressure. Suggestions are provided as to how to determine the frequency and duty cycle required for maximum noise suppression with the least amount of water.
by Paul Aaron Ragaller.
S.M.
Ragaller, Paul Aaron. "Microjet based noise control of supersonic jets on carrier decks." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/87980.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 131-134).
The effectiveness of ground plane water microjet control on the noise generated by a supersonic, ideally expanded, Mach 1.5, impinging jet was determined. Using a converging-diverging nozzle with a design Mach number of 1.5, the jet was operated at temperatures ranging from 60 to 1700°F. Six microjets were installed in the ground plane in a circular configuration at a radial spacing of 1.53 nozzle diameters, and an angle of 0 and 300 to tangential. Baseline and control temperature readings at the ground plane and acoustic readings at the sideline angles of 70, 80 and 900 were obtained with the microjets operating at pressures ranging from 200 to 900 psig. Additionally, in order to determine the fluid-mechanical mechanisms responsible for the control effect on the noise, high-speed images and video were obtained and analyzed. From measurements of the average and fluctuating ground plane temperature measurements, it was found that modifications to the High Temperature Supersonic Jet Facility at Florida State University allowed for measurements of impinging jet characteristics that were congruent with previous studies. Ground plane microjets were found to be effective in reducing feedback tones as a result of the impinging geometry of the jet. They were also effective at reducing the broadband spectral noise for lower temperatures. At temperatures higher than 600°F, however, an increase in the broadband noise was produced as a result of water microjets. At microjet injection pressures at and above 800 psig, additional noise suppression was achieved for the cold operating condition. From obtained high-speed images and video, it was found that the breakup of the microjet in the shear layer (of the shear variety), and the entrainment of fine mist into the inception of the shear layer was responsible for the reduction in strength and size of large-scale vortical structures. At higher pressures, additional noise suppression is produced as a combined result of the breaking of the feedback loop and the microjet's ability to penetrate to the high-speed side of the shear layer.
by Paul Aaron Ragaller.
Ph. D.
Debost, Sophie. "Valve seating impact as a source of valve train noise." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11780.
Full textGautam, Prashanta. "Investigation of air-borne noise generation mechanisms in tire noise." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron148552634330808.
Full textBhaskar, Atul. "Damping in mechanical vibration : new methods of analysis and estimation." Thesis, University of Cambridge, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314853.
Full textWang, Raymond Yi-Wen. "Bearing fault detection and oil debris monitoring by adaptive noise cancellation." Thesis, University of Ottawa (Canada), 2008. http://hdl.handle.net/10393/27609.
Full textMacumber, Daniel Lee 1981. "Blade tonal noise reduction using tail articulation at high Reynolds number." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/27879.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (leaves 141-144).
The biologically inspired method of tail articulation is investigated as a means of reducing tonal noise due to the stator wake blade interaction in underwater vehicles. This work is experimental in nature and conducted in the closed channel water tunnel at Naval Undersea Warfare Center in Newport, Rhode Island. Tail articulation is carried out with a life scale stator model with hinged flapping tail designed to (i) operate in freestream velocities corresponding to Reynolds number in the range 75,000 < Re < 300,000 and (ii) operate at frequencies up to 30 Hz in order to investigate the range of Strouhal number 0.0 < St < 0.35. Velocity measurements in the active stator wake are carried out by Laser Doppler Velocimetry, LDV, and Particle Image Velocimetry, PIV, in order to investigate the effects of tail articulation. Time averaged measurements of the stator wake by LDV show that Strouhal number of the tail articulation has a dominant effect on the time mean stator drag. Instantaneous phase averaged measurements of the stator wake by PIV show three regimes of the stator wake as Strouhal number is increased; quasi-steady wake spreading, vortex roll up, and strong vortex wake. A low order model describing the creation and convection of vorticity by tail articulation is developed which describes wake phenomena observed in experimental measurements. A two dimensional blade force simulation coupled with the reduced order tail articulation model is used to perimetrically search for a tail motion resulting in lower unsteady blade forces.
(cont.) Finally, a three dimensional unsteady propeller simulation using both experimental wake velocity data by PIV and simulated wake velocity data generated by the reduced order tail articulation model is used to predict the effect of tail articulation on radiated noise. These simulations indicate that reduction of radiated noise by 5 dB or more is possible using tail articulation.
by Daniel Lee Macumber.
S.M.
Opila, Daniel F. (Daniel Francis) 1981. "Active control of underwater propulsor noise using polypyrrole conducting polymer actuators." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/89909.
Full textHo, Nhut Tan 1974. "Design of aircraft noise abatement approach procedures for near-term implementation." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/30340.
Full textIncludes bibliographical references (p. 116-119).
Advanced aircraft noise abatement approach procedures -- characterized by decelerating, continuous descent approaches using idle thrust, and enabled by flight guidance technologies such as GPS and FMS -- have been shown to reduce operational aircraft noise on communities surrounding airports. However, implementation in the near future presents two challenges. The first is to mitigate the adverse effects on aircraft performance of uncertainties in pilot response, weather, and other system components. The second is to enhance the ability of air traffic controllers to separate aircraft that are decelerating at different rates. The work in this thesis primarily addresses the first challenge by developing, first, a methodology to determine the optimum design parameters for a continuous descent approach, and, second, a new pilot cueing system. The methodology involved: 1) conducting a simulator-based, human factors experiment to obtain models of pilot delay in extending flaps/gear in conditions with and without turbulence; 2) formulating the procedure's parameters as strategic and tactical control variables; 3) using the pilot delay models and the parameter formulation to perform a Monte Carlo Simulation to resolve the conflicting objectives of reducing noise and increasing probability of target achievement. Simulation results showed that the flap schedule has to be designed for a 50-ft- higher-than the target altitude without turbulence, and a 200-ft for turbulence; 4) determining the feasibility space of the parameters in different wind conditions. Results showed that when the wind uncertainty is large, accounting for the uncertainty in the procedure design significantly reduces the effectiveness of the procedure.
(cont.) A new pilot cueing system that does not require additional aircraft automation was developed to help pilots manage the deceleration of aircraft and achieve target conditions in a changing environment. The cueing system, consisting of gates (i.e., altitude/speed checkpoints) and a recommended flap schedule, was designed and evaluated in a second experiment using a desktop simulator which showed that gates reduce target error to within five knots and provide comparable performance to that of more automated systems without increasing pilot workload. Because the gates have the potential of enabling aircraft to fly consistent speed profiles, it is hypothesized that their implementation would address the second challenge by enhancing the controller's ability to predict aircraft trajectories and their future separation.
by Nhut Tan Ho.
Ph.D.
Li, Shih-Hung. "Progressive learning of endpoint feedback systems with model uncertainty and sensor noise." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38158.
Full textReba, Ramona Andris. "A theoretical study of leading-edge devices for active and passive control of wake-airfoil interaction noise." Diss., The University of Arizona, 2000. http://hdl.handle.net/10150/284280.
Full textGobat, Jason I. "Reducing mechanical and flow-induced noise in the surface suspended acoustic receiver." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/55317.
Full textIncludes bibliographical references (p. 65-66).
The Surface Suspended Acoustic Receiver (SSAR) is a free-drifting platform intended for use as a receiver in large scale acoustic tomography experiments. Early prototypes of the SSAR exhibited very poor signal-to-noise ratios in the frequency band of the hydrophones. This thesis details efforts to reduce the hydrophone noise level by combining the analysis of experimental data with the results from numerical models. Experiments were conducted to quantify both the frequency content and magnitude of noise generated on the SSAR. Through a program of sea trials and pond testing, two noise sources were identified. The dominant source of noise in the SSAR is velocity dependent flow noise that results from turbulent pressure fluctuations on the hydrophones. A second noise source results from the acceleration sensitivity of the hydrophones in conjunction with high frequency accelerations present in the hydrophone array cable. These high frequency accelerations also show a velocity dependence. The presence of the acceleration-induced noise leads to correlations between the signals from adjacent hydrophones, thus distorting the typical picture that flow noise should be uncorrelated along an array. The primary methods of eliminating the noise are encapsulating the hydrophone in a flow shield, eliminating the array cable, and slowing the system down by replacing the wave following surface buoy with a spar buoy. Using the experimental results, empirical relationships between hydrophone velocity and expected noise level are formed for both shielded and unshielded hydrophones. The numerical models developed as a part of this effort are then used to predict the velocities for a wide range of possible SSAR configurations. The models can also provide information, such as system tensions, that is useful in evaluating the longevity and survivability of SSARs. Modeled design fixes include subsurface component changes as well as comparing a wave following surface buoy to a spar buoy.
by Jason I. Gobat.
M.S.
Moulton, Carey Lloyd. "The Near Field Acoustics of the Active Noise Control of a Model Propeller." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20000726-233230.
Full textThe Near field properties of a 6" radius model propeller, and the Active Noise Control(ANC) of the Blade Passing Tone (BPT) have been studied. The study has been careful toidentify and separate the effects of the hydrodynamic near field and the geometric near field. The near and far field radiation regions of a model propeller were consideredseparately. Firstly to determine if far field control affects the near field noise levels and secondly to determine how the far field noise levels are affected by near field control. It has been found that active noise control (ANC) of the propeller blade passing tone (BPT)can be achieved within the geometric near field, however the extent of the effective control is small. The near field optimized ANC can result in as much as 10.5 dB ofreduction of the BPT, however this noise reduction can only be achieved over a small spatial region. For this experimental arrangement there is no effective ANC directlybehind the propeller. Whenever ANC is optimized for near field noise it results in far field noise levels of up to 15.2 dB above the uncontrolled far field propeller levels. The far field optimized control shows no detrimental effects in the near field noise environment.
Elsheikh, Mutasim. "A Numerical and Experimental Investigation of Flow Induced Noise In Hydraulic Counterbalance Valves." Thesis, University of South Florida, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=3714983.
Full textThe main objective of this study is to explore the complex fluid flow phenomena that result in the generation of a high frequency noise in counterbalance valves through an experimental and numerical investigation of the flow. Once the influence of the different components involved in noise generation is established, a secondary objective is the introduction of design modifications that eliminate the undesired effect without altering the operation envelope or the performance of the valve.
A hydraulic test bench was used to carry out an experimental investigation of the noise generation process. A computer based data acquisition system was used to record pressure fluctuations, flowrates and hydraulic oil temperatures in a production valve under a variety of operational conditions. Extensive experimental measurements and numerical modeling lead to the hypothesis that noise generation is the result of an acoustic resonance triggered by shear layer instability at the valve inlet. The pressure gradients developed when the shear layer entrains the stagnant fluid in the valve main cavity cause the layer to become unstable and oscillate. The oscillation frequency will depend on a great number of factors such as valve geometry, pressure and velocity gradients and the density and viscosity of the fluid. It is postulated that the observed noise is generated when this frequency matches one of the resonant frequencies of the valve cavity.
The proposed mechanism is theoretically poorly understood and well beyond simplified analysis, its accurate numerical simulation is computational very intensive requiring sophisticated CFD codes. The numerical investigation was carried out using STAR-CCM+, a commercially available CFD code featuring 3-D capabilities and sophisticated turbulence modeling. Streamline, pressure, velocity-vector and velocity-scalar plots were obtained for several valve configurations using steady and unsteady state flow simulations.
An experimental and numerical analysis of an alternative valve geometry was carried out. Experimental results demonstrated a greatly reduced instability range. The numerical analysis of the unsteady behavior of the shear-layer streamlines for both valves yielded results that were compatible with the experimental work.
The results of this investigation promise a great positive impact on the design of this type of hydraulic valves.
Yoon, Jun Young Ph D. Massachusetts Institute of Technology. "Linear iron-core permanent magnet motor with high force and low acoustic noise." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/110891.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 323-328).
Acoustic noise and associated vibration are potentially troubling characteristics of electric machines including variable-reluctance motors, induction machines, and permanent magnet synchronous motors. The severity of this problem depends on the types of motors and their applications. One exemplary case where the vibro-acoustic noise becomes especially detrimental is iron-core linear motors operating at high acceleration and targeted for high accuracy applications. In this doctoral research, we identify root causes of the vibro-acoustic noise of iron-core linear motors, and create magnetic designs paired with control algorithms to achieve high-acceleration with low noise and vibration. Vibro-acoustic noise issues of rotary machines have been researched over the years, but not as much work has been done for linear machines whose major causes of noise generation might be different from rotary motors due to the structural differences. This thesis focuses on the following aspects: 1) Investigate the causes and develop and verify theory for acoustic noise emitted from linear iron-core machines. 2) Design, construct, and test a new linear iron-core motor that can simultaneously provide high force and low noise. 3) Design and construct an experimental linear motor testbed to investigate the noise issue of conventional iron-core motors, and to demonstrate the new motor's desired performance of high force and low noise. We hypothesize and experimentally validate that the acoustic noise and associated vibration of linear iron-core permanent magnet motors are caused by high frequency force harmonics vibrating the moving stage. Such stage vibration can be transmitted through the system structure and can also radiate as acoustic noise, thereby disturbing precision machines. In order to reduce high frequency force harmonic content, our new motor has fine teeth, narrow slots with high slot aspect ratio, five phases, and a moving Halbach magnet array. With our new fine-tooth motor, we significantly reduce the vibro-acoustic noise of linear iron-core motors while substantially enhancing the shear stress density, compared to conventional 3-4 combination iron-core motors. The overall acoustic noise level in Pascals is reduced by 93 % during the acceleration period with non-skewed magnets. In terms of the sound pressure level (SPL), this is a significant noise reduction from 83 dB to 60 dB. The cogging-driven and velocity dependent noise, which is dominant in constant velocity regions, is also significantly reduced in our new motor design. Our fine-tooth motor design reduces the cogging force by a factor of 10-to-1 when using skewed magnets, thereby reducing cogging driven acoustic noise by 90 % in Pascals. We also present in this thesis the force performance of our new fine-tooth motor both in simulations and experiments. Our new motor shows predicted shear stress improvements of 28 % (from 0.090 N/mm2 to 0.115 N/mm 2) at the prototype practical power level of 10 W/mm and 84% (from 0.167 N/mm 2 to 0.308 N/mm2) at an anticipated ultimate RMS (root mean square) current density limit in the coil wires of 50 A/mm2 , relative to a conventional motor. Understanding causes of the vibro-acoustic noise and how to mitigate it in both the design and post-design phases provides useful tools to achieve high-performance and quiet linear motion devices. This research will benefit many industrial applications which require both high throughput and high accuracy.
by Jun Young Yoon.
Ph. D.
Clements, Kristen Lynn. "Active control of an automobile suspension system for reduction of vibration and noise." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30359.
Full textThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 79-82).
A new method for controlling road noise transmitted through the suspension system of an automobile was developed, using a Lincoln LS automobile as the target vehicle. In this vehicle, road surface roughness generates vibrations that are transmitted into the automobile primary through a single bushing (the "point 4 bushing") on each of the front suspension control arms. An electromagnetic actuator was designed, built, and tested on a Lincoln LS with simulated roads noise. The actuator applies a force across the point 4 bushing, in response to accelerations of the vehicle frame, just inboard of the bushing, with the goal of reducing the net forces transmitted into the vehicle frame, which ultimately produce unwanted interior noise. Several tonal controllers were developed, each designed to operate in a narrow frequency band, and to eliminate the cross member (frame) vibration just inside the point 4 bushing. The tonal controllers were able to eliminate cross member vibration at the desired frequency. Eliminating the cross member vibration resulted in modest reductions interior sound levels. A successful vibration control system (in this vehicle) would need to eliminate cross member vibrations over frequency range 100 to 200 Hz. However, a broadband controller with this electromagnetic actuator system proved to be difficult, due to undesirable non-minimum phase dynamics.
by Kristen Lynn Clements.
S.M.
Jain, Tarun (Tarun Kumar). "Membrane transfer process for the creation of low-noise solid state nanopore devices." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/67619.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (p. 81-83).
Nanopore sensors are an emerging technology whereby the modulation of a current trace upon passage of the analyte through the nanopore is used to infer the properties of the analyte. This technology is particularly attractive because it is label-free, rapid, and intrinsically single molecule. However, the ability to infer molecular properties with nanometer precision, either in size or sequencing, is obscured by noise in the measurement. The precision of this inference can be significantly improved by reducing noise and by performing multiple measurements on the same molecule. Solid state nanopores, made in free standing membranes, however, have traditionally exhibited high levels of capacitive noise at 100 kHz bandwidths, as well as poor confinement of the electric field around the nanopore. In this thesis, a novel device concept is designed for creating solid state nanopores whereby the free standing membrane is transferred over a PDMS microchannel. By eliminating the silicon wafer backing, capacitive noise is dramatically reduced. Furthermore, the microchannel confines the electric field outside the nanopore, thereby enhancing the ability to perform multiple measurements.
by Tarun Jain.
S.M.
Snow, Christopher L. "An Investigation of the Geometry, Transmission Error and Noise of Injection Molded Gears." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420560177.
Full textVan, der Spuy Sybrand Johannes. "The design of a low-noise rotor-only axial flow fan series." Thesis, Stellenbosch : University of Stellenbosch, 1997. http://hdl.handle.net/10019.1/20977.
Full textAFRIKAANSE OPSOMMING: 'n Ontwerpsroetine vir die ontwerp van 'n reeks enkelrotor aksiaalwaaiers is ontwikkel. Die roetine is toegepas deur twee verskillende reekse aksiaalwaaiers te ontwerp. Die eerste ontwerp was vir 'n algemene toepassings enkelrotor aksiaalwaaier. Die waaierreeks is ontwerp, gebou en getoets in samewerking met Howden Air Industries vir beide navorsings - en kommersieIe doeleindes. Die tweede ontwerp was vir 'n lae geraas waaierreeks. Die reeks is ontwerp, gebou en getoets deur die Universiteit van Stellenbosch vir navorsingsdoeleindes. Die onwerpsteorie het gebruik gemaak van die beginsel van lemverkorting, waardeur een lem ontwerp is om op al die groottes waaierdeursnee te pas. Die waaierreekse is ontwerp vir waaierdeursnee tussen 315 mm en 1000 mm. Die rotors is ontwerp om 'n uitlaatsneIheidsprofiel te gee wat 'n minimum verlies in kinetiese energie toelaat. Die algemene toepassings waaierontwerp het gekonsentreer rondom die gewilde waaierdeursnee van 500 mm, 560 en 630 mm. Dit is ontwerp vir 'n rotorspoed van 1440 met 'n kommersieel beskikbare waaierreeks wat as verwysing gebruik is. Die lae geraas waaierreeks het op slegs een waaiergrootte gekonsentreer, naamlik 630 mm. Die lae geraas waaierreeks is ook ontwerp met vorentoe gekurfde lemme. Die res van die ontwerpsbeginsels was dieseIfde as vir die algemene toepassings waaierreeks. Die F-reeks vleuelprofiele is gebruik vir die lemseksies van beide waaierreekse. Beide waaiereekse is getoets vir waaiergeraas en -effektiwiteit deur gebruik te maak van die BS 848 Standaarde deel 1 (] 980) en 2 (] 985). 'n Verskeidenheid van waaierdeursnee van die algemene toepassings waaierreeks is getoets om die waaier se vertoning oor 'n gebied van waaiergroottes te bepaal. Die resuItaat was 'n waaierreeks met 'n wye gebied van effektiewe werking, asook uitstekende geraaseienskappe. 'n 630 mm Deursnee waaier is gebruik om die lae geraas waaier te toets. Die toetse het 'n waaier getoon wat beide hoe effektiwiteit en lae geraaseienskappe het. Die afname in waaiergeraas wat verkry is met die lae geraas waaier, in vergelyking met die algemene toepassings waaier, regverdig egter rue die werk en kostes verbonde aan die ontwerp van die waaierreeks nie.
Goley, George. "Investigation and Improvement of Occupational and Military Noise Exposure Guidelines: Evaluation of Existing and Modified Noise Exposure Metrics Using Historical Animal Data." University of Cincinnati / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1275924272.
Full textMcGee, David Michael. "Experimental studies of fluid-borne noise generation in a marine pump." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/10945/24164.
Full textSasidharan, Nair Unnikrishnan. "Jet noise source localization and identification." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1482412964456451.
Full textJaffer, Sadiq. "Noise adaptive particle filtering for mobile robot applications." Thesis, University of Warwick, 2010. http://wrap.warwick.ac.uk/34557/.
Full textVaidya, Nikhilesh Avanish. "NOISE SPECTRUM OF A QUANTUM POINT CONTACT COUPLED TO A NANO-MECHANICAL OSCILLATOR." Diss., Temple University Libraries, 2017. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/447885.
Full textPh.D.
With the advance in nanotechnology, we are more interested in the "smaller worlds". One of the practical applications of this is to measure a very small displacement or the mass of a nano-mechanical object. To measure such properties, one needs a very sensitive detector. A quantum point contact (QPC) is one of the most sensitive detectors. In a QPC, electrons tunnel one by one through a tunnel junction (a "hole"). The tunnel junction in a QPC consists of a narrow constriction (nm-wide) between two conductors. To measure the properties of a nano-mechanical object (which acts as a harmonic oscillator), we couple it to a QPC. This coupling effects the electrons tunneling through the QPC junction. By measuring the transport properties of the tunneling electrons, we can infer the properties of the oscillator (i.e. the nano-mechanical object). However, this coupling introduces noise, which reduces the measurement precision. Thus, it is very important to understand this source of noise and to study how it effects the measurement process. We theoretically study the transport properties of electrons through a QPC junction, weakly coupled to a vibration mode of a nano-mechanical oscillator via both the position and the momentum of the oscillator. %We study both the position and momentum based coupling. The transport properties that we study consist of the average flow of current through the junction, given by the one-time correlation of the electron tunneling event, and the current noise given by the two-time correlation of the average current, i.e, the variance. The first comprehensive experimental study of the noise spectrum of a detector coupled to a QPC was performed by the group of Stettenheim et al. Their observed spectral features had two pronounced peaks which depict the noise produced due to the coupling of the QPC with the oscillator and in turn provide evidence of the induced feedback loop (back-action). Benatov and Blencowe theoretically studied these spectral features using the Born approximation and the Markovian approximation. In this case the Born approximation refers to second order perturbation of the interaction Hamiltonian. In this approximation, the electrons tunnel independently, i.e., one by one only, and co-tunneling is disregarded. The Markovian approximation does not take into account the past behavior of the system under time evolution. These two approximations also enable one to study the system analytically, and the noise is calculated using the MacDonald formula. Our main aim for this thesis is to find a suitable theoretical model that would replicate the experimental plots from the work of Stettenheim et al. Our work does not use the Markovian approximation. However, we do use the Born approximation. This is justified as long as the coupling between the oscillator and QPC is weak. We first obtain the non-Markovian unconditional master equation for the reduced density matrix of the system. Non-Markovian dynamics enables us to study, in principle, the full memory effects of the system. From the master equation, we then derive analytical results for the current and the current noise. Due to the non-Markovian nature of our system, the electron tunneling parameters are time-dependent. Therefore, we cannot study the system analytically. We thus numerically solve the current noise expression to obtain the noise spectrum. We then compare our noise spectrum with the experimental noise spectrum. We show that our spectral noise results agree better with the experimental evidence compared to the results obtained using the Markovian approximation. We thus conclude that one needs non-Markovian dynamics to understand the experimental noise spectrum of a QPC coupled to a nano-mechanical oscillator.
Temple University--Theses
Hake, Mariah I. (Mariah Inez). "Experimental design to determine the effect of temperature and Mach number on entropy noise." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/92184.
Full textCataloged from PDF version of thesis.
Includes bibliographical references (pages 37-38).
The Osney Laboratory sought to create an entropy noise test rig that could determine the relationship between entropy noise and the flow parameters of temperature change and nozzle Mach number. The apparatus simulates entropy noise in an aero engine. In the test rig, compressed air enters an anechoic labyrinth, flows through a settling chamber that straightens airflow, and then goes to the entropy wave generator. The entropy wave generator forms entropy waves through electric heating. Entropy waves are then accelerated in a convergent-divergent nozzle to produce entropy noise. Microphones at the end of the rig detect entropy noise readings as acoustic sound. Air exits through an anechoic termination. The test rig allows for easy changes in temperature and Mach number so variation in entropy noise with different input values can be tested. Project stages include literature compilation, 3D computer-aided design, part revision, material specification, and finally supervision of manufacture.
by Mariah I. Hake.
S.B.
Esgandari, Mohammad. "Simulation methods for vehicle disc brake noise, vibration & harshness." Thesis, University of Birmingham, 2015. http://etheses.bham.ac.uk//id/eprint/5762/.
Full textTsai, Chung-Tien. "Effect of airfoil thickness on high-frequency gust interaction noise." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185962.
Full textLong, Guo. "Subband Adaptive Filtering for Active Broadband Noise Control with Application to Road Noise inside Vehicles." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1595846098921553.
Full textChoi, Jae Jeen 1975. "Active noise control in supersonic impinging jets using pulsed microjets : actuator design, reduced-order modeling." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/38260.
Full textIncludes bibliographical references (p. 104-110).
In recent years, it has been demonstrated that direct microjet injection into the shear layer of the main jet disrupts the feedback loop inherent in high speed impinging jet flows, thereby significantly reduces the adverse effects. The amount of noise reduced by microjet actuation is known to be dependent on nozzle operating conditions. In this paper, two active control strategies using microjets are suggested to maintain a uniform, reliable, and optimal reduction of these tones over the entire range of operating conditions. In the first method, a quasi-closed loop control strategy is proposed using steady microjet injection and the Proper Orthogonal Decomposition (POD) algorithm. The most energetic spatial mode of the unsteady pressure along the nozzle diameter is captured using the POD, which in turn is used to determine the distribution of microjet intensity along the nozzle exit. Preliminary experimental results from a STOVL supersonic jet facility at Mach 1.5 show that the quasi-closed loop control strategy, in some cases, provides an additional 8,10 dB reduction compared to axisymmetric injection at the desired operating conditions. The second method consists of a pulsed microjet injection, motivated by the need to further improve the noise suppression.
(cont.) It was observed that the pulsed microjet was able to bring about the same noise reduction as steady injection using approximately 40% of the corresponding mass flow rate of the steady microjet case. Moreover, as the duty cycle increased, the performance of pulsed injection was further enhanced and was observed to completely eliminate the impinging tones at all operating conditions. In order to obtain an optimal performance of the actuator, a new model of the impinging jet flow field is suggested based on a collision model of two identical vortices. In addition to the colliding vortex model, a two-mode feedback model that captures both the low and high-frequency Rossiter mode was suggested to investigate the role of pulsed microjet in the feedback loop. Due to the fact that a low frequency pulsing (16.4 Hz) brought about additional reduction compared to high frequency pulsing, the presence of low frequency mode is identified. In the context of the analytic model, the effect of pulsing is modeled using a input-shaping controller that accomplishes noise-reduction through a suitable redistribution of the acoustic excitation over the high and low frequencies.
by Jae Jeen Choi.
Ph.D.
Duan, Jie. "Active Control of Vehicle Powertrain and Road Noise." University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1312479913.
Full textRaffler, Oliver. "A roller test bench for the evaluation of automotive vehicle noise, vibration and harshness." Thesis, Nelson Mandela Metropolitan University, 2015. http://hdl.handle.net/10948/21646.
Full textWade, Andrew David. "Investigation into road rumble in a light utility vehicle." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1297.
Full textDuan, Jie. "Active Control of Vehicle Powertrain Noise Applying Frequency Domain Filtered-x LMS Algorithm." University of Cincinnati / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1243614246.
Full textFeng, Tao. "Design and Analysis of Efficient Adaptive Algorithms for Active Control of Vehicle Interior Sound." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1490354549915601.
Full textKikalas, Raimondas. "Konvejerių keliamo triukšmo tyrimai ir triukšmo mažinimo būdai." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2009. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2009~D_20090626_101514-54766.
Full textIn this graduation thesis Conveyor noise and possibilities to reduce it are investigated. Common conveyors in food industry, their types and operating principles are reviewed. Main factors causing noise in chain conveyors and ways of reducing them are described. Three experimental investigations were completed. Investigation process, conveyoring line conditions are described, results presented. There are conclusion and used literature list written down at the end of thesis. Thesis includes 60 A4 format pages and 4 A4 format pages of supplement. 36 bibliographical sources are used.
Azarpeyvand, Mahdi. "Some aspects of RANS based jet noise prediction." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/66622/.
Full textBolze, Victor Matthew. "Static and Dynamic Transmission Error Measurements and Predictions and their Relation to Measured Noise for Several Gear Sets." The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392889635.
Full textLee, Ming-ran. "Vibro-acoustic analysis of computer disk drive components with emphasis on electro-mechanical noise sources /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487846354483737.
Full textLi, Zheng. "Spur gear teeth contact analysis on power-train transmission noise, vibration and harshness." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3163/.
Full textSTELZER, GREGORY JON. "A MAGNETORHEOLOGIC SEMI-ACTIVE ISOLATOR TO REDUCE NOISE AND VIBRATION TRANSMISSIBILITY IN AUTOMOBILES." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1029363540.
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