Applied Research Laboratory Research Articles

Research on Bottlenecks and Countermeasures for the Development of Young Teachers in Vocational Colleges

Young teachers play a pivotal role in workforce development within vocational colleges, yet often face challenges adjusting to their new responsibilities. This study aimed to identify barriers through a questionnaire survey of 11 young teachers. Findings revealed the greatest difficulties lay in adapting instruction methods to meet the diverse needs of learners, navigating constraints on research due to insufficient laboratory facilities and funding, and uncertainty around career progression pathways. To address these issues, we proposed three countermeasure strategies. First, vocational colleges should strengthen partnerships between industry and education through joint training programs and applied research laboratories to enrich curriculum design and enhance teachers’ practical skills. Secondly, establishing formal mentorship programs pairing new educators with experienced mentors can facilitate the transition into their roles and offer careerguidance. Third, colleges should actively encourage the involvement of young teachers in skills competitions to cultivate their practical skills. This research highlights the multifaceted challenges faced by young teachers and the imperative for targeted solutions to strengthen the vocational education workforce.

Convolutional neural networks for signal identification and extraction and seabed classification

Sound underwater source (SUS) charges can be used for seabed characterization experiments. Many SUS were deployed during experiments in the New England MudPatch during 2017 and 2022. The goal of this work is to automatically detect and extract SUS signals in the dataset and then perform seabed classification on the extracted SUS signals. A binary classifier CNN is trained on simulated SUS charges and measured ambient noise to detect if a SUS signal is present in one minute pressure waveforms. The trained CNN model is then used to identify and extract the SUS signals from the measured data on the 52-channel PROTEUS L-array deployed by Applied Research Laboratories, University of Texas at Austin. This automated extraction process expedites the identification and time alignment of hundreds of SUS signals. The extracted signals will then be input to a ResNet-18 network trained on synthetic signals to perform seabed classification using a catalog of 34 seabeds. Lessons learned from the automated identification and extraction process will be presented as well as a statistical analysis of the seabed classification results. [Work supported by the Office of Naval Research, Grant N00014-22-12402.]

Fundamental acoustics concepts taught through the development of an impedance tube

As part of its mission to educate students, Applied Research Laboratories, The University of Texas at Austin (ARL:UT) employs student technicians to assist on a variety of ongoing research projects. Recently, an undergraduate student technician was tasked with the design and fabrication of a low-cost impedance tube for use in characterizing acoustic materials. To assist the student in developing a set of design requirements, and to determine whether preliminary data were being accurately collected and processed, a set of homework problems were developed to teach the student the fundamental concepts in acoustics necessary for impedance tube development. Homework problems required utilizing both travelling- and standing-wave solutions to the one-dimensional (1D) Helmholtz equation, as well as a basic understanding of the relationships between pressure, particle velocity, and acoustic impedance. Homework solutions were compared with 3D finite element simulations and with experimental data collected using the impedance tube. We felt that these homework problems were effective at conveying basic ideas in acoustics to a student with no prior knowledge in the subject, and how those concepts could be used to solve real-world problems.

History of high-amplitude underwater sound source research at the University of Texas Applied Research Laboratories

The Applied Research Laboratories has an extensive history of supporting underwater acoustic research through the development of novel high-amplitude underwater sound sources, such as the Plasma Sound Source (PSS), the Combustive Sound Source (CSS) and the Rupture Induced Underwater Sound Source (RIUSS). These sources generate broadband acoustic pulses capable of long-range propagation and seabed penetration, and can be viewed as alternatives to explosive sources. The PSS is based on the discharge of electrical energy stored in capacitors which results in a plasma bubble. The CSS consists of a submersible combustion chamber, open to the water, which is filled with a combustive mixture that is ignited via spark. Upon ignition, the combustive mixture is converted into high temperature combustion byproducts which expand and ultimately collapse, thereby radiating an acoustic pulse. In this talk, the motivation for alternative impulsive sources is discussed and the PSS is briefly discussed. Next, the early development of CSS, through the end of the 1990’s, is described, which led to the basic understanding of the CSS and the parameters required to modify its output. In the following talk further development of CSS, and the invention of RIUSS, are discussed. [Work supported by ONR and NAVO.]

The ONR three octave research array at Penn State

A new, large diameter towed research array has been built to support the experimental efforts of the Office of Naval Research (ONR) Ocean Acoustics Program. Array development was a collaborative effort between the Centre for Maritime Research and Experimentation (CMRE) in La Spezia, Italy, and the Penn State Applied Research Laboratory (PSU). PSU chose the array specifications based on discussions within the underwater acoustics community, prior measurement experience, cost efficiency, and flexibility in scientific measurements, while CMRE designed and assembled the array. The design includes three, forward-nested acoustic apertures cut for 1, 2, and 4 kHz, and hence, has been dubbed the Three Octave Research Array (THORA) in deference to its predecessor, the Five Octave Research Array (FORA). However, this system has a modular design to allow addition of acoustic apertures if scientific interest and sponsor support warrant. The array currently consists of a 50 m acoustic module and a 25 m vibration isolation module to help isolate the acoustic module from cable strum. This ship towed system has nearly 1 km of tow cable and a maximum measurement depth of 500 m. The array’s design, its use in the ONR NESMA23 Pilot experiment, and data quality will be discussed.

Large-chamber reciprocity calibration for microbarometers

The Penn State Applied Research Laboratory (PSU) and Sandia National Laboratories (SNL) have implemented a reciprocity-based primary calibration technique in SNL’s infrasound calibration chamber. The goal in this work is primary calibration of microbarometers from 0.01 to 10.0 Hz. The National Center for Physical Acoustics at the University of Mississippi designed and built the chamber, which SNL has modified and currently operates. This chamber incorporates two moving coil loudspeakers capable of operating in receive and transmit mode. PSU developed the calibration technique and the required electronics to take advantage of these two reciprocal loudspeakers, while SNL installed this hardware and made the required test measurements. Because the chamber is large (1400 l), the chamber volume dominates the acoustical admittance thereby reducing the dependence of the calibration on the physical characteristics of the loudspeakers and reducing calibration uncertainty. However, laboratory tests have found increased uncertainty at very low frequencies ( < 0.05 Hz). This is due to reduced loudspeaker response and increasing noise within the chamber at these frequencies. This talk will discuss the large-chamber reciprocity method, important considerations for reducing uncertainty in this implementation, and limitations of this method.

Further development of high-amplitude underwater sound sources at The University of Texas Applied Research Laboratories

Following the early research on the Combustive Sound Source (CSS), described in the previous talk, additional development occurred in the 2000’s and beyond, which included work on both the CSS and a new source, the Rupture Induced Underwater Sound Source (RIUSS). Development of the CSS in this era included maximizing the output of the source, investigating the use of CSS in arrays, and towing the source. The CSS was also deployed in surveys conducted during Shallow Water ’06 and the Seabed Characterization Experiment. In part due to lessons learned during those surveys, the RIUSS was conceived and developed. The RIUSS functions by placing a rupture disk over an evacuated chamber and mechanically breaking the disk (either by striking on demand or via hydrostatic pressure) at a specified depth to initiate a volume collapse that produces an impulsive acoustic waveform. The development and use of each sound source will be provided along with high-speed underwater video, examples of signatures, and examples of the efficacy of the sources in ocean acoustics research. [Work Supported by ONR and NAVO].

Strongly focused nonlinear surface acoustic wave beams in isotropic solids

A promising direction in the tailored control of quantum materials is the modification of their structure-function relationship via engineered laser-driven shock waves. In order to inform how the laser excitation should be tailored to optimize the effect of the shock waves, a model is desired for strongly focused nonlinear surface waves in crystals. A model was developed previously in the paraxial approximation for weakly diffracting nonlinear surface wave beams in isotropic solids [Shull et al., JASA 97, 2126 (1995)]. Harmonic generation and shock formation were investigated numerically in that work for sources with uniform amplitude distributions, with analytical solutions for the fundamental and second harmonic obtained for weakly focused Gaussian beams. Here, numerical results are reported for shock formation in focused nonlinear surface waves obtained using a model unrestricted by the paraxial approximation in order to accommodate strong focusing in isotropic solids. Removal of the restriction to isotropic solids is work in progress based on representation of the wave field in terms of its angular spectrum and a model for planar nonlinear surface waves in crystals [Hamilton et al., JASA 105, 639 (1999)]. [Work supported by the IR&D Program at Applied Research Laboratories.]

Fabrication of optimized transducer head masses via additive manufacturing

The Applied Research Laboratory conducted an investigation into additive manufacturing (AM) as an avenue to improve transducer head mass performance. Techniques, such as powder bed fusion (PBF) of metals and direct ink writing (DIW) of ceramics, offer benefits, including increased design freedom and faster design iteration. The transducer head mass acts as an acoustic radiator and receiver, and is required to have a high stiffness-to-weight ratio. Aluminum is commonly used for this application due to a balance between performance and cost. AlSi10Mg, an aluminum alloy, is readily printed via PBF, making it an excellent candidate for geometric optimization. A technique known as topology optimization has been used to great effect, reducing weight of the part and bridging the performance gap between aluminum and AlBeMet. High performance composites and ceramics are sometimes used for head masses, however their high price and long turnaround time often eliminate them as an option. Recently, DIW has been used to manufacture boron carbide head masses. DIW reduces the need for expensive machining, reducing the cost and time required to employ such a high performance material. This presentation will discuss the optimization of the transducer head mass, including topology optimization of AlSi10Mg and DIW of B4C.

Идентификация кристаллов тартратных солей в составе осадка вин

Crystalline sediment of potassium hydrotartrate and calcium tartrate in wines is a major problem of wine industry. Reliable identification of crystals can establish the cause of their formation and facilitate appropriate technological solutions. The research objective was to study the morphological features of potassium and calcium salts of tartaric acid via microscopy.
 The study featured natural crystal sediments that developed in 105 samples of white and red wines over six months after the end of fermentation, as well as when crystallization was provoked by freezing. The microscopic examination involved a Micmed-5 optical microscope and a PHENOMproX scanning electron microscope. Identification of cations in the composition of crystals followed the method of energy-dispersive spectroscopy, as well as the method of quality reaction with sulfate-anion in acidic medium.
 Co-precipitation of colloidal substances was typical of potassium hydrotartrate. It violated the crystal lattice construction and determined the wine color, polymorphism (truncated ellipsoid → lanceolar → rhomboid → geometrically irregular shapes), surface roughness, and optical opacity. The expressiveness increased with the crystal growth (3–350 μm). Calcium tartrate demonstrated no evolutionary changes; it was morphologically uniform, colorless, and transparent. Its crystals had smooth faces and clear edges, regardless of their size (1–150 μm) and the chemical composition of wine.
 The research systemized the morphological features of tartrate crystals formed in wines. The obtained results are important for the technochemical control in the process of destabilization diagnosis. The data can be recommended for further studies in applied research laboratories and institutes.

Graduate acoustics education in the Cockrell School of Engineering at The University of Texas at Austin

While graduate study in acoustics takes place in several colleges and schools at The University of Texas at Austin (UT Austin), including Communication, Fine Arts, Geosciences, and Natural Sciences, this poster focuses on the acoustics program in Engineering. The core of this program resides in the Departments of Mechanical Engineering (ME) and Electrical and Computer Engineering (ECE). Acoustics faculty in each department supervise graduate students in both departments. One undergraduate and nine graduate acoustics courses are taught in ME and ECE. Instructors for these courses include staff at Applied Research Laboratories at UT Austin, where many of the graduate students have research assistantships. The undergraduate course, taught every fall, begins with basic physical acoustics and proceeds to draw examples from different areas of engineering acoustics. Three of the graduate courses are taught every year: a two course sequence on physical acoustics, and a transducers course. The remaining six graduate acoustics courses, taught in alternate years, are on nonlinear acoustics, underwater acoustics, ultrasonics, architectural acoustics, wave phenomena, and acoustic metamaterials. An acoustics seminar is held most Fridays during the long semesters, averaging over ten per semester since 1984. The ME and ECE departments both offer Ph.D. qualifying exams in acoustics.

Full-Scale Reynolds Number Testing of Rotor Hub Drag and Wake Turbulence

A 1:4.25-scale model of a generic helicopter rotor hub was tested at Reynolds numbers ranging from 1. 75× 106 to 7×106 at advance ratio of 0.2 in The Pennsylvania State University Applied Research Laboratory Garfield Thomas 48-inch diameter water tunnel. Measurements including drag and wake characteristics were performed up to full-scale Reynolds number with respect to an industry-representative helicopter rotor hub. In particular, the variation of drag and flow field with Reynolds number was characterized. Load measurements were conducted using an improved load cell design, with greater accuracy than in previous experiments. Wake velocity was measured using laser Doppler velocimetry at two downstream planes, yielding velocity statistics to the second order. Improved load measurement accuracy and wake velocity spatial resolution, at full-scale Reynolds number, provide a unique dataset for computational fluid dynamics validation as part of the Penn State Rotor Hub Flow Prediction Workshops and physical insight into rotor hub flows.

Creatinine-Detecting Laser Diode-Induced Fluorescence Detection System

Under highly alkaline conditions, creatinine reacts with 3.5-dinitrobenzoic acid (DNB) to produce a product that can absorb ultraviolet light at a wavelength of 400 nm and emit fluorescence at a wavelength of 491 nm. Thus, creatinine concentration can be calculated using fluorescence intensity. A novel fluorescence-based bioassay for rat creatinine that is capable of rapid detection at a low cost was developed in this study. A fluorescence sensing system was established using a micro-spectrometer, a 3-D translation stage, and a laser diode (LD) to measure various concentrations of serum creatinine. The measurable range was 12.5– <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$300 ~\mu $ </tex-math></inline-formula> mol/L ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}^{2} $ </tex-math></inline-formula> = 0.996), and the limit of detection (LOD) was <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5 ~\mu $ </tex-math></inline-formula> mol/L. The intraday precision and accuracy ranges were 7.33%–10.11% and 81.82%–99.75%, respectively, while the interday precision and accuracy ranges were 3.08%–9.39% and 86.75%–87.85%, respectively. Additionally, the test results for rat serum were compared with those from the National Laboratory Animal Center of National Applied Research Laboratories in Taiwan, and the correlation coefficient was determined to be 0.80.

Automated Defect Recognition for Additive Manufactured Parts Using Machine Perception and Visual Saliency.

Metal additive manufacturing (AM) is known to produce internal defects that can impact performance. As the technology becomes more mainstream, there is a growing need to establish nondestructive inspection technologies that can assess and quantify build quality with high confidence. This article presents a complete, three-dimensional (3D) solution for automated defect recognition in AM parts using X-ray computed tomography (CT) scans. The algorithm uses a machine perception framework to automatically separate visually salient regions, that is, anomalous voxels, from the CT background. Compared with supervised approaches, the proposed concept relies solely on visual cues in 3D similar to those used by human operators in two-dimensional (2D) assuming no a priori information about defect appearance, size, and/or shape. To ingest any arbitrary part geometry, a binary mask is generated using statistical measures that separate lighter, material voxels from darker, background voxels. Therefore, no additional part or scan information, such as CAD files, STL models, or laser scan vector data, is needed. Visual saliency is established using multiscale, symmetric, and separable 3D convolution kernels. Separability of the convolution kernels is paramount when processing CT scans with potentially billions of voxels because it allows for parallel processing and thus faster execution of the convolution operation in single dimensions. Based on the CT scan resolution, kernel sizes may be adjusted to identify defects of different sizes. All adjacent anomalous voxels are subsequently merged to form defect clusters, which in turn reveals additional information regarding defect size, morphology, and orientation to the user, information that may be linked to mechanical properties, such as fatigue response. The algorithm was implemented in MATLAB™ using hardware acceleration, that is, graphics processing unit support, and tested on CT scans of AM components available at the Center for Innovative Materials Processing through Direct Digital Deposition (CIMP-3D) at Penn State's Applied Research Laboratory. Initial results show adequate processing times of just a few minutes and very low false-positive rates, especially when addressing highly salient and larger defects. All developed analytic tools can be simplified to accommodate 2D images.

The legacy of the five octave research array and its impact on future towed array development

The five octave research array (FORA) was developed and implemented in support of the Office of Naval Research (ONR) Ocean Acoustics program’s experimental efforts. Dr. John R. Preston spearheaded planning, development, and experimental operations of this well-known acquisition system. Planning and development of the system took place between 1997 and 2002, while engineering assessment and array enhancements continued through 2004. From initial delivery to the Penn State Applied Research Laboratory to the present, the FORA made possible over 20 very successful sea trials. These trials were primarily in the interest of oceanographic and underwater acoustics, as well as signal processing research. The data collected, with John at the helm, fostered hundreds (if not thousands) of scholarly works, while John’s collaborative nature allowed an enormous number of researchers and students to benefit from the data and experience in at-sea experimentation. One of John’s final contributions was to renew planning and discussions for a replacement research array to continue in place of the aging FORA, which was becoming less dependable and increasingly expensive to maintain. This talk will discuss the development and history of the FORA, its involvement in a selection of collaborative ONR trials, and the FORA replacement acquisition system.

Acoustic radiation force and torque on a spheroid near an interface

Acoustic radiation force and torque on a spheroid of arbitrary size near a rigid or pressure release interface are calculated using expansions of the pressure field in terms of both spherical and spheroidal wave functions. The spheroidal expansion coefficients are obtained by satisfying the boundary conditions at the interface and at the surface of the spheroid. Conditions at the interface are satisfied using a virtual (image) spheroid, while satisfying conditions at the spheroid surface require the use of addition theorems for spheroidal wave functions. The radiation force and torque are expressed as a summation of terms involving products of the coefficients in spherical wave expansions of the incident and scattered fields [Ilinskii et al., J. Acoust. Soc. Am. 144, 568–576 (2018)]. Far-field asymptotes are used to relate the spheroidal and spherical harmonic expansion coefficients analytically. Results from the present analytical model are compared with those from a finite-element model. The effect of the interface on the radiation force and torque relative to that on a spheroid in a free field is discussed. [B.E.S. is supported by the Applied Research Laboratories Chester M. McKinney Graduate Fellowship in Acoustics.]

Artificial intelligence in aircraft design and the role of professor V.G. Maslov’s scientific school in the process of its development

The article was prepared for the 95th anniversary of the birth of Valentin Grigorievich Maslov, Doctor of Science (Engineering), Professor, founder of the school for optimal design of aircraft engine parameters, head of the engine CAD system department (Department 6) of the applied research laboratory (ONIL-2) of Kuibyshev Aviation Institute named after academician S.P. Korolyov. The stages of creating the theoretical foundation for optimal design of aircraft are discussed. The role of Professor V.G. Maslov in the formalization of knowledge in aircraft design in a context of uncertainty and the importance of multi-criteria assessment of design solutions are described. The work of Department 6 ONIL-2 (KuAI-SSAU), led by Valentin Grigorievich, provided Samara scientific school with a leading position in the field of optimal design of engines for aircraft of varying function. These works contributed to the formation of a modern understanding of the intellectualization of systems and the successful start of work in the field of their creation. The development of Professor V.G. Maslovs ideas in the works of his students is shown.

David Blackstock and the University of Rochester

This presentation provides perspective on David T. Blackstock at the University of Rochester in Rochester, NY. Dr. Blackstock’s interactions with the University of Rochester began early in his academic career. In the early 1960’s, he was an associate professor in the Department of Electrical Engineering at the University of Rochester for several years. Beginning in 1970, he moved to The University of Texas at Austin for his long academic career with the Applied Research Laboratories and the Department of Mechanical Engineering. Then in 1987, enabled through collaborations with Dr. Edwin L. Carstensen, Dr. Blackstock returned to Rochester to spend his summers at the University of Rochester. That same year, he became a visiting member of the Rochester Center for Biomedical Ultrasound directed by Dr. Carstensen. Dr. Blackstock continued to spend summers at the University of Rochester for several decades. Summers with Dr. Blackstock were filled with engaging scientific discussions, research collaborations, and interactions with many students and faculty in various departments. During the summer, he regularly taught his Fundamentals of Acoustics course and, during select years, his Nonlinear Acoustics course. Dr. Blackstock’s longtime engagement with the University of Rochester greatly impacted the careers and lives of many students and faculty.

David T. Blackstock: Scholar, teacher, mentor, and gentleman

David T. Blackstock was born in Austin, Texas in 1930. After earning B.S. and M.S. degrees in physics at University of Texas at Austin he spent two years at Wright-Patterson Air Force Base, where he developed an interest in acoustics working under Henning von Gierke on hearing protection. He then joined F. V. Hunt’s group at Harvard University and earned a Ph.D. in applied physics in 1960 with a doctoral thesis in nonlinear acoustics, ultimately his lifelong passion. Following three years at General Dynamics and seven years at University of Rochester, David returned to UT in 1970 to join its Applied Research Laboratories, and in 1987 he became Professor of Mechanical Engineering. Among David’s legacies is his formulation of a convenient framework for implementing weak-shock theory. Combining analytical, computational, and experimental approaches, he proceeded to investigate acoustic saturation, finite-amplitude noise, suppression of sound by sound, parametric array in air, sonic boom, therapeutic ultrasound, and other fundamental problems in nonlinear acoustics. David was widely known as an exceptionally caring man, whether bringing Soviet scientists and their research to the attention of the West, teaching and mentoring graduate students, or through extensive service in the ASA and International Commission for Acoustics.

Bridging cultures with acoustical materials research

This talk will provide a short overview and insights associated with the education and early career of the author over the past two decades and how his experiences with different cultures, both social and professional, has influenced scientific advancements. This will include a short overview of formal education in both the United States and France and professional growth as a researcher at the Applied Research Laboratories at The University of Texas at Austin (UT) and then as a professor in the Department of Mechanical Engineering at UT. The talk will highlight research done in each context and how those experiences have improved outcomes in scientific and personal contexts.