Scholarly Works, Mechanical Engineering

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https://hdl.handle.net/10919/23262

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3D printing vending machine
(United States Patent and Trademark Office, 2016-08-16)
A vending machine for creating a three-dimensional object having an enclosure having an exterior and interior. The interior receives and houses at least one three-dimensional printer. An interface for accepting an instruction associated with an object to be printed and transmitting the instruction to the printer. A storage section for storing a printed object that provides access to the printed part but limits or prohibits access to the interior.
Accelerometer Based Method for Tire Load and Slip Angle Estimation
Singh, Kanwar Bharat; Taheri, Saied (MDPI, 2019-04-28)
Tire mounted sensors are emerging as a promising technology, capable of providing information about important tire states. This paper presents a survey of the state-of-the-art in the field of smart tire technology, with a special focus on the different signal processing techniques proposed by researchers to estimate the tire load and slip angle using tire mounted accelerometers. Next, details about the research activities undertaken as part of this study to develop a smart tire are presented. Finally, novel algorithms for estimating the tire load and slip angle are presented. Experimental results demonstrate the effectiveness of the proposed algorithms.
Acoustic Effects Accurately Predict an Extreme Case of Biological Morphology
Zhang, Z. W.; Truong, S. N.; Müller, Rolf (American Physical Society, 2009-07-17)
The biosonar system of bats utilizes physical baffle shapes around the sites of ultrasound emission for diffraction-based beam forming. Among these shapes, some extreme cases have evolved that include a long noseleaf protrusion (sella) in a species of horseshoe bat. We have evaluated the acoustic cost function associated with sella length with a computational physics approach and found that the extreme length can be predicted accurately from a fiducial point on this function. This suggests that some extreme cases of biological morphology can be explained from their physical function alone.
An acoustic micro-transmitter enabling tracking of sensitive aquatic species in riverine and estuarine environments
Deng, Zhiqun Daniel; Li, Huidong; Lu, Jun; Xiao, Jie; Myjak, Mitchell J.; Martinez, Jayson J.; Wang, Yuxing; Zhang, Jiguang (2021-05-19)
Conservation of aquatic species requires in-depth understanding of their movement and behavior and their interactions with man-made hydraulic structures. Acoustic telemetry is a primary method to remotely track in 3 dimensions (3D) aquatic animals implanted with transmitters. The transmitter's weight and size are the major limiting factors because the transmitter should not affect the animals' natural behavior. Here, we present an acoustic micro-transmitter that weighs 0.08 g in air, only 1/3 that of existing technologies. The transmitter offers a source level of 148 dB (reference: 1 mu Pa at 1 m) and a service life of 30 days at a 5-s transmission rate. Nearly 100% of tagged fish were detected in field studies, demonstrating the viability of this technology for studying species of early life stages. Information resulting from the use of this technology provides valuable insight for ecological and environmental policy making and resource management worldwide.
Acoustic performance of a stretched membrane and porous blanket combination
Thomas, W. A. Jr.; Hurst, Charles J. (Acoustical Society of America, 1976)
The sound absorption performance of an acoustic absorber consisting of a stretched circular membrane placed a short distance in front of a fiberglass blanket was both measured and predicted. Both theoretical and experimental analyses were restricted to plane acoustic waves. Theoretical predictions indicated that the membrane-blanket combination would have a sound power absorption coefficient nearly equal to the sound power absorption coefficient of the blanket alone if the incident acoustic plane wave drove the membrane at one of its resonance frequencies. Theoretical analysis also predicted that the sound power absorption coefficient would approach zero when the membrane was driven at an antiresonance frequency by the incident acoustic plane wave. Experimental agreement with theoretical predictions was good for several membrane-blanket combinations. The results show that membrane-blanket combinations can be effective acoustic absorbers in frequency ranges which do not include the antiresonance frequencies of the membrane. The equations developed may be used to predict the acoustic performance of any membrane-blanket combination.
Acoustics 1991: Active structural acoustic control
Fuller, Chris R.; Silcox, Richard J. (Acoustical Society of America, 1992-01-01)
In summary, the ASAC technique has demonstrated much potential in aerospace and marine applications. Future work will center on extending these techniques to broadband disturbances, more complex structures and improved modeling. It is known that optimizing transducer positions is as important as increasing the number of control channels. A multidisciplinary approach is required to synthesize a design procedure that integrates the elements of structural acoustics, transducer, and control technology. The pay off will be in significant cost and weight savings, and in performance improvements for other industrial applications.
Actin Filaments Couple the Protrusive Tips to the Nucleus through the I-BAR Domain Protein IRSp53 during the Migration of Cells on 1D Fibers
Mukherjee, Apratim; Ron, Jonathan Emanuel; Hu, Hooi Ting; Nishimura, Tamako; Hanawa-Suetsugu, Kyoko; Behkam, Bahareh; Mimori-Kiyosue, Yuko; Gov, Nir Shachna; Suetsugu, Shiro; Nain, Amrinder Singh (Wiley-VCH, 2023-03)
The cell migration cycle, well-established in 2D, proceeds with forming new protrusive structures at the cell membrane and subsequent redistribution of contractile machinery. Three-dimensional (3D) environments are complex and composed of 1D fibers, and 1D fibers are shown to recapitulate essential features of 3D migration. However, the establishment of protrusive activity at the cell membrane and contractility in 1D fibrous environments remains partially understood. Here the role of membrane curvature regulator IRSp53 is examined as a coupler between actin filaments and plasma membrane during cell migration on single, suspended 1D fibers. IRSp53 depletion reduced cell-length spanning actin stress fibers that originate from the cell periphery, protrusive activity, and contractility, leading to uncoupling of the nucleus from cellular movements. A theoretical model capable of predicting the observed transition of IRSp53-depleted cells from rapid stick-slip migration to smooth and slower migration due to reduced actin polymerization at the cell edges is developed, which is verified by direct measurements of retrograde actin flow using speckle microscopy. Overall, it is found that IRSp53 mediates actin recruitment at the cellular tips leading to the establishment of cell-length spanning fibers, thus demonstrating a unique role of IRSp53 in controlling cell migration in 3D.
Activation of bacterial channel MscL in mechanically stimulated droplet interface bilayers
Najem, Joseph S.; Dunlap, Myles D.; Rowe, Ian D.; Freeman, Eric C.; Grant, John Wallace; Sukharev, Sergei; Leo, Donald J. (Springer Nature, 2015-09-08)
MscL, a stretch-activated channel, saves bacteria experiencing hypo-osmotic shocks from lysis. Its high conductance and controllable activation makes it a strong candidate to serve as a transducer in stimuli-responsive biomolecular materials. Droplet interface bilayers (DIBs), flexible insulating scaffolds for such materials, can be used as a new platform for incorporation and activation of MscL. Here, we report the first reconstitution and activation of the low-threshold V23T mutant of MscL in a DIB as a response to axial compressions of the droplets. Gating occurs near maximum compression of both droplets where tension in the membrane is maximal. The observed 0.1-3 nS conductance levels correspond to the V23T-MscL sub-conductive and fully open states recorded in native bacterial membranes or liposomes. Geometrical analysis of droplets during compression indicates that both contact angle and total area of the water-oil interfaces contribute to the generation of tension in the bilayer. The measured expansion of the interfaces by 2.5% is predicted to generate a 4-6 mN/m tension in the bilayer, just sufficient for gating. This work clarifies the principles of interconversion between bulk and surface forces in the DIB, facilitates the measurements of fundamental membrane properties, and improves our understanding of MscL response to membrane tension.
Active control of aircraft engine inlet noise using compact sound sources and distributed error sensors
(United States Patent and Trademark Office, 1996-05-07)
An active noise control system using a compact sound source is effective to reduce aircraft engine duct noise. The fan noise from a turbofan engine is controlled using an adaptive filtered-x LMS algorithm. Single multi channel control systems are used to control the fan blade passage frequency (BPF) tone and the BPF tone and the first harmonic of the BPF tone for a plane wave excitation. A multi channel control system is used to control any spinning mode. The multi channel control system to control both fan tones and a high pressure compressor BPF tone simultaneously. In order to make active control of turbofan inlet noise a viable technology, a compact sound source is employed to generate the control field. This control field sound source consists of an array of identical thin, cylindrically curved panels with an inner radius of curvature corresponding to that of the engine inlet. These panels are flush mounted inside the inlet duct and sealed on all edges to prevent leakage around the panel and to minimize the aerodynamic losses created by the addition of the panels. Each panel is driven by one or more piezoelectric force transducers mounted on the surface of the panel. The response of the panel to excitation is maximized when it is driven at its resonance; therefore, the panel is designed such that its fundamental frequency is near the tone to be canceled, typically 2000-4000 Hz.
Active control of coupled wave propagation in fluid-filled elastic cylindrical shells
Brevart, Bertrand J.; Fuller, Chris R. (Acoustical Society of America, 1993-09-01)
A control approach to reduce the total power propagating along fluid-filled elastic cylinders is analytically investigated. The motion of the cylinder is described by the Kennard shell equations fully coupled to the interior acoustic field. The vibration disturbance source is a pre-determined free propagating wave of either n = 0 or n = 1 circumferential order and the control forces considered are appropriate harmonic line forces radially applied to the structure. The radial displacement of the shell wall at discrete locations downstream of control forces is minimized using feedforward quadratic optimal theory. The difference of total power flow through the system before and after control is then used to evaluate the impact of the fluid on the performance of the control approach. For the breathing circumferential mode (n = 0), owing to the coupling between the two media, the fluid decreases the control performance when the disturbance is a structural-type incident wave. When the disturbance is a fluid-type incident wave, with a pressure near field concentrated at the shell wall, significant reductions of the transmitted power flow can be achieved. For the beam mode (n = 1), even though the control is applied to the structure, the fluid increases the control performances below the first acoustic cut-off frequency and decreases it above this frequency.
Active control of far-field sound radiated by a rectangular panel - a general analysis
Pan, Jie; Snyder, Scott D.; Hansen, Colin H.; Fuller, Chris R. (Acoustical Society of America, 1992-04-01)
In this paper a general analysis is presented for the active control of the far-field harmonic sound radiated by a rectangular panel that is built into an infinite baffle. In this analysis, the panel vibration may be generated by either airborne sound (incident sound field) or by structure borne vibrations. The far-field radiated sound is controlled either by acoustical sources or vibration sources. Minimization of both the local sound pressure and the total power output is considered. Analytical results for the particular case involving minimization of the sound pressure at a single point are compared with experimental data. The physical mechanisms involved for different control sources (vibration or acoustic) are demonstrated analytically. For the case of vibration control sources, the panel modal velocity components are adjusted to produce far-field sound control. This can be done either by decreasing their amplitudes, and/or by changing the temporal phases of the panel modes. However, for acoustic control sources, the far-field sound is minimized by alteration of the radiation impedance seen by the vibrating panel and the control sources.
Active control of noise transmission through rectangular plates using multiple piezoelectric or point force actuators
Wang, Bor-Tsuen; Fuller, Chris R.; Dimitriadis, Emilios K. (Acoustical Society of America, 1991-11-01)
This paper analytically demonstrates the use of multiple piezoelectric actuators bonded to the surface and point force actuators applied directly to a plate to reduce sound transmission through the plate. A harmonic plane wave incident on a simply supported, thin rectangular plate mounted in an infinite baffle was considered as the primary source. Both multiple piezoelectric and point force actuators are separately used as secondary (control) sources to attenuate the sound transmission through the plate. An optimal process was applied to obtain the input voltages of the piezoelectric actuators and the magnitude of the point forces, so that the radiated acoustic power can be minimized. Results show that a reduction of sound transmission through the plate is successfully; achieved, if the proper size, number, and position of the piezoelectric or point force actuators are selected. Additionally, a comparison showed that point force actuators provide more effective control of the sound transmission than piezoelectric actuators; however, piezoelectric patches have more practical implementation than point force shakers, because of their low cost and light weight.
Active control of sound radiation due to subsonic wave scattering from discontinuities on fluid-loaded plates. I: Far-field pressure
Gu, Yi; Fuller, Chris R. (Acoustical Society of America, 1991-10-01)
Active control of sound radiation due to subsonic wave scattering from discontinuities represented by a line constraint or by a uniform reinforcing rib positioned on a fluid-loaded infinite plate is analytically studied. The mathematical models are based on the plate vibration and sound radiation due to a line force or a line moment solved in the spectral k domain. For simplicity, the far-field pressure is estimated by the stationary phase approach. Feed-forward control is achieved by adding secondary line forces applied to the plate near the discontinuity. The amplitudes of control forces are determined by the optimal solution of a cost function that integrates the far-field radiated acoustic intensity in a semicylindrical space around the discontinuity. The results show that for subsonic incident waves, high reduction in radiated pressure due to spectral wave scattering at the discontinuities is possible with two active control forces located near the discontinuity. The amount of sound reduction as well as the residual directivity pattern is shown to depend upon the number and location of the control forces.
Active control of sound radiation from a fluid-loaded rectangular uniform plate
Gu, Yi; Fuller, Chris R. (Acoustical Society of America, 1993-01-01)
Active control of sound radiation from a simply supported rectangular fluid-loaded plate is analytically studied. The plate is assumed to be excited by a point force at subsonic frequencies. The solution to the plate motion is based on the admissible functions for an in vacuo homogeneous plate, which is also the basis for Fourier decomposition of the fluid loading [B. E. Sandman, J. Acoust. Soc. Am. 61, 1502-1510 (1977) ]. Feed-forward control is carried out by using point forces applied to the plate. The amplitudes of the control forces are determined by the optimal solution of a quadratic cost function that integrates the far-field radiated acoustic pressure over a hemisphere in the radiation half-space. The results show that for subsonic disturbances, a high global reduction in radiated pressure is possible. For on-resonant excitations, a reasonable sound reduction can be achieved with up to two properly located active control forces, and for off-resonant excitations, up to four control forces may be necessary. The results thus indicate that the active structural acoustic control approach will provide large attenuations in radiated sound when edge mode coupling induced by heavy fluid loading is present. The number and location of the control forces are determined so as to suppress the efficiently radiating modes. The far-field directivity pattern, the plate velocity autospectrum in the two-dimensional wave number domain, and the near-field pressure distribution are studied.
Active control of sound radiation from a plate using a polyvinylidene fluoride volume displacement sensor
Charette, Francois; Berry, Alain; Guigou, Catherine (Acoustical Society of America, 1998-03-01)
This paper presents a new volume displacement sensor (made of shaped strips of PVDF film) and the experimental implementation of this sensor in an active control system. A design strategy for a PVDF sensor detecting the volume displacement induced by a vibrating 2D structure is presented. It is based on the modal representation of the plate response. It actually consists in designing a PVDF sensor, composed of several shaped PVDF strips bonded to the surface of the structure, in such a way that the output signal of the sensor is directly proportional to the volume displacement. The design methodology is based on the experimental measurements of the plate mode shapes (eigenfunctions) and is valid for any type of boundary conditions. The experimental implementation of such a volumetric sensor in an active control system is then presented. The experimental results obtained validates this new type of volume displacement sensor.
Active control of sound radiation from a simply supported beam: Influence of bending near-field waves
Guigou, Catherine; Fuller, Chris R. (Acoustical Society of America, 1993-05-01)
Active control of sound radiation from a baffled simply supported finite beam is analytically studied. The beam is subjected to a harmonic input force and the resulting acoustic field is minimized by applying a control point force. For a single frequency, the flexural response of the beam subject to the input and control forces is expressed in terms of flexural waves of both propagating and near-field types. The optimal control force complex amplitude is derived by minimizing the acoustic radiated pressure at one point located in the far field. The far-field radiated pressure, the displacement of the vibrating beam, and the one-dimensional wave-number spectrum of the beam velocity are extensively studied. In order to further understand control mechanisms, the radiated pressure due to the flexural propagating wave and the flexural near-field wave, respectively, is investigated at the minimization point before and after the control is involved. The analysis shows that, when the control is applied, the combination of the radiated pressure due to the two different types of waves (as their associated radiation is out-of-phase) at the minimization point causes the large pressure attenuation. These results demonstrate that structural near fields are important in terms of predicting performance in active control of structurally radiated sound.
Active isolation of vibration with adaptive structures
Guigou, Catherine; Fuller, Chris R.; Wagstaff, Peter R. (Acoustical Society of America, 1994-07-01)
The problem of actively isolating the periodic vibrations of a rigid machine mounted on a supporting flexible structure is usually approached by applying the active inputs in parallel or series with the passive inputs. This has a number of disadvantages which are related to the development of a high power, compact yet stiff/active isolation unit. In this experimental work, a new approach in which the receiving structure is considered to have adaptive properties is studied. The aim is to control the transmitted vibrations by distributed arrays of piezoelectric transducers bonded to the receiving structure. The experimental rig consists of a rigid thick plate (the machine) supported at the corners by four elastic springs mounted on a thin clamped-free elastic steel plate (the receiving structure). The thick plate is driven by a harmonic force input. Response in the receiving panel is measured with a scanning laser vibrometer. Active inputs to the receiving structure are induced by three pairs of piezoceramic actuators bonded to the surface and configured to induce bending. The error sensors consist of up to two polyvinylidene fluoride (PVDF) strips attached to the panel surface in various positions. The control approach uses a two channel feedforward adaptive LMS algorithm implemented on a TMS320C25. The results show that the first three modes of the system can be controlled efficiently when driven ''on resonance,'' thus effectively isolating the vibrating structure from the ''machine'' raft input. However, when the system is driven ''off resonance,'' the vibrations of the receiving structure proved more difficult td reduce effectively. The paper presents vibration distribution of the receiving plate with and without control for a number of input frequencies as well as a variety of control transducer configurations.
Active Vibration Isolation Using an Induced Strain Actuator with Application to Automotive Seat Suspensions
Malowicki, Mark; Leo, Donald J. (Hindawi, 2001-01-01)
Active vibration isolation of automotive seats requires actuators that achieve millimeter-range displacements and forces on the order of 300 N. Recent developments in piezoceramic actuator technology provide a means for achieving these force and displacement levels in a compact device. This work demonstrates that prestressed, curved piezoceramic actuators achieve the force and displacement levels required for active isolation of automotive seats. An estimate of the force and displacement requirements are obtained from numerical simulations on a four-degree-of-freedom car and seat model that utilize representive road accelerations as inputs. An actuator that meets these specifications is designed using piezoceramic materials. Free displacement of 4.4 mm and blocked force greater than 300 N are measured. The actuator is integrated within a dead mass setup that simulates the isolation characteristics of an automotive seat. Control experiments demonstrate that active vibration is achievable with realistic road disturbances. Feedback control is able to eliminate any amplification due to mechanical resonance and reduce the isolation frequency from 9.5 Hz to 2 Hz.
An Adaptive Actuation Mechanism for Anthropomorphic Robot Hands
Kontoudis, George P.; Liarokapis, Minas; Vamvoudakis, Kyriakos G.; Furukawa, Tomonari (Frontiers, 2019-07-05)
This paper presents an adaptive actuation mechanism that can be employed for the development of anthropomorphic, dexterous robot hands. The tendon-driven actuation mechanism achieves both flexion/extension and adduction/abduction on the finger's metacarpophalangeal joint using two actuators. Moment arm pulleys are employed to drive the tendon laterally and achieve a simultaneous execution of abduction and flexion motion. Particular emphasis has been given to the modeling and analysis of the actuation mechanism. More specifically, the analysis determines specific values for the design parameters for desired abduction angles. Also, a model for spatial motion is provided that relates the actuation modes with the finger motions. A static balance analysis is performed for the computation of the tendon force at each joint. A model is employed for the computation of the stiffness of the rotational flexure joints. The proposed mechanism has been designed and fabricated with the hybrid deposition manufacturing technique. The efficiency of the mechanism has been validated with experiments that include the assessment of the role of friction, the computation of the reachable workspace, the assessment of the force exertion capabilities, the demonstration of the feasible motions, and the evaluation of the grasping and manipulation capabilities. An anthropomorphic robot hand equipped with the proposed actuation mechanism was also fabricated to evaluate its performance. The proposed mechanism facilitates the collaboration of actuators to increase the exerted forces, improving hand dexterity and allowing the execution of dexterous manipulation tasks.
Adaptive feedforward and feedback methods for active/passive sound radiation control using smart foam
Guigou, Catherine; Fuller, Chris R. (Acoustical Society of America, 1998-07-01)
This work investigates and compares the potential of adaptive feed forward and feedback methods for a hybrid active/passive radiation control using smart foam. The radiating structure is a vibrating plate mounted in a rigid baffle in an anechoic chamber. The smart foam, designed to reduce sound by the action of the passive absorption of the foam (which is effective at higher frequencies) and the active input of an embedded PVDF element driven by an oscillating electrical input (which is effective at lower frequencies), is positioned on the plate. The first test consists of using a single-input single-output (SISO) adaptive feedforward LMS controller to minimize the error sensor signal provided by a microphone in the close proximity of the active element under narrow-band excitation and broadband random excitation. For feedforward control, two different reference signals are considered: the voltage sent to the piezoceramic actuator driving the plate (disturbance) and the signal from an accelerometer directly mounted on the plate (more realistic in practice). In the latter case, the effect of the smart foam on the reference signal (or acceleration level) can be taken into account (feedback removal). An adaptive feedback controller is also implemented to avoid the use of a reference signal. In this case, a reference signal is obtained from the error signal using the internal model approach. The results from these three different control methods are compared in terms of the sound attenuation achieved. For broadband excitation, a feedforward adaptive control with an external reference is shown to be more efficient for this arrangement than a feedback adaptive control.

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