Ultrasonic Burst Research Articles

Gold removal from e-waste using high-intensity focused ultrasound

The demand for rare and precious metals (RPMs), e.g. gold, is increasing, as these are used in the ever-increasing amount of electronics needed for technological development and digitalization. Due to their rarity, virgin mining of RPMs is becoming more difficult and expensive. At the same time, over 62Mt of e-waste is created globally each year. The high concentration of gold and other RPMs in e-waste makes it an excellent source for recycling. Unfortunately, current recycling methods need to separate the different metals and the current pyrometallurgical and hydrometallurgical processes also create toxic pollutants, large amounts of wastewater and require highly corrosive substances. Here we present a new method for gold removal for the purpose of recycling, using only water and high-intensity focused ultrasound to induce material erosion through cavitation. An 11.8MHz ultrasonic transducer is used to first image the sample to locate gold-coated pads on discarded printed circuit boards (PCBs) and subsequently to remove only the gold layer. We demonstrate that the gold removal can be controlled by the number of transmitted ultrasonic bursts and that the energy efficiency is optimal when only minute amounts of the nickel layer beneath are also removed. Removing solely the gold layer also decreases the need for further processing steps. This greener gold removal method for e-waste is therefore well aligned with, and contributing to, the United Nations Sustainable Development Goal 12: Ensure sustainable consumption and production patterns.

Study on the ultrasonic cavitation damage to early atherosclerotic plaque

Ultrasonic cavitation can damage surrounding material and be used for destruction of the target tissue. In this paper, we investigated the interaction between atherosclerotic plaque (AP) and cavitation bubbles to determine whether the mechanical effect of cavitation damage could be potentially useful in therapy for treating atherosclerotic plaques. A two-bubble–fluid–solid model was established to study the dynamic behavior of bubbles near the AP and the AP damage by ultrasound-induced cavitation. A low-intensity focused ultrasound (LIFU) transducer was used for testing cavitation-based AP damage. We found that the nonlinear oscillation of bubbles causes the relative positions of the bubbles to shift, either toward or away from one another, these phenomena lead to changes in the bond failure rate between the fiber bundles, and the value of BRF exhibits an upward trend, this is the reason why the fibers suffered from reversible stretching and compressing. However, the AP damage is irreversible and diminishes as the number of cycles in the ultrasonic burst. It appears that the bigger the radii, regardless of whether the bubble (3 − i)’s and bubble i's radii are equal, the greater the AP damage. Ultrasonic cavitation therapy may not be appropriate for advanced AP patients, and the calcified tissue has a greater impact on the stability of the plaque. The damage area should be strictly selected. Additionally, the tissue damage phenomenon was found in experimental results. This work shows that the severity of AP damage is correlated with acoustic parameters and the surrounding environment from both simulation and experimental perspectives. The results show that ultrasonic cavitation may provide a new choice for the treatment of AP.

Fluidic Ultrasound Generation for Non-Destructive Testing.

Air-coupled ultrasonic testing (ACU) is a pioneering technique in non-destructive testing (NDT). While contact testing and fluid immersion testing are standard methods in many applications, the adoption of ACU is progressing slowly, especially in the low ultrasonic frequency range. A main reason for this development is the difficulty of generating high amplitude ultrasonic bursts with equipment that is robust enough to be applied outside a laboratory environment. This paper presents the fluidic ultrasonic transducer as a solution to this challenge. This novel aeroacoustic source uses the flow instability of a sonic jet in a bistable fluidic switch to generate ultrasonic bursts up to 60kHz with a mean peak pressure of 320Pa. The robust design allows operation in adverse environments, independent of the operating fluid. Non-contact through-transmission experiments are conducted on four materials and compared with the results of conventional transducers. For the first time, it is shown that the novel fluidic ultrasonic transducer provides a suitable acoustic signal for NDT tasks and has potential of furthering the implementation of ACU in industrialapplications.

Enhanced removal of heavy metal from stainless steel pickling sludge by sonochemical cavitation: Physical fragmentation and chemical activation

Stainless steel pickling sludge (SSPS) is a noxious solid waste containing heavy metals (Fe, Cr, Mn, and Ni). Herein, an ultrafast ultrasonic-assisted leaching (UAL) extraction method for heavy metals from SSPS is proposed. The effects of key leaching factors, including acid lixiviant, acid dosage, leaching time, liquid-to-solid ratio, and leaching temperature, on the leaching efficiency of Fe, Cr, Ni and Mn in SSPS were systematically studied, followed by the theoretical optimization by response surface methodology. The leaching efficiencies of Fe, Mn, Ni, and Cr were significantly enhanced to 98.6%, 90.74%, 90.83%, and 92.25% within 15 min, which were nearly nine times higher than the acid leaching process. The ultrasonic burst broke up the SSPS and increased the contact area (mass transfer effect) of the heavy metal leaching reaction. In addition, kinetic and thermodynamic studies shown that sonochemical action could significantly promote the initial leaching efficiency of heavy metals. This work provided a super-fast method to recovery of heavy metal from SSPS, which shows great potential for the actual application.

Cyclodextrin-loaded nanobubbles reduce cholesterol and atherosclerosis in vivo

Abstract Background Ischemic heart disease (IHD) is the leading cause of mortality and morbidity worldwide. Atherosclerosis, a chronic inflammatory disease, is the main contributor to IHD. However, atherosclerosis is commonly left undiagnosed and untreated. Our study aims to create a theranostic nanobubbles (NBs), with ultrasonic properties for diagnostic imaging and at the same time for the delivery of 2-Hydroxypropyl-beta-cyclodextrin (CD), an FDA-approved drug to dissolve cholesterol crystals. Methods and Results Using polybutlycyanoacrylate, we created polymeric NBs. The incorporation of near-infrared dye (IR780) resulted in a multimodal contrast NB, which allows in vitro and in vivo visualization on both ultrasound and optical imaging. Furthermore, these NBs can be triggered by ultrasonic bursts to release their dye/drug payload. The safety profile of the NBs, post-incorporation of CD (CDNBs), demonstrated excellent biocompatibility in vitro using cell culture and in human blood. Cellular uptake of CP increased by 2.4x when using CPNBs compared to free CD (p<0.00001). In vivo biodistribution demonstrated that the NBs circulate in blood plasma for 48 hours, with a peak at 1-hour post-injection. In a mouse model of atherosclerosis, ApoE-/- mice on high-fat diet, we intravenously injected CDNBs, free CD or NBs only fortnightly for 8 weeks. En face Oil Red O-staining showed a significant reduction in total plaque area in the CDNB-treated group, as compared to the control animals treated with free CD and with NBs only (p>0.01). There was also a significant reduction in blood plasma cholesterol for the CDNBs-treated mice as compared to the control mice (p>0.01). Conclusion We demonstrated the ability to load CDs into NBs. These CDNBs are taken up by immune cells. The passive accumulation of CDNPs in the atherosclerotic lesions, resulted in the release of CD and the reduction of total plaque area in the entire aorta. These CDNBs treated mice also have a reduced cholesterol level in their plasma. CDNBs represent a novel theranostic nanocarrier with a high potential of clinical translation and ultimately major benefits to patients with atherosclerosis.

First Series Using Ultrasonic Propulsion and Burst Wave Lithotripsy to Treat Ureteral Stones.

Our goal was to test transcutaneous focused ultrasound in the form of ultrasonic propulsion and burst wave lithotripsy to reposition ureteral stones and facilitate passage in awake subjects. Adult subjects with a diagnosed proximal or distal ureteral stone were prospectively recruited. Ultrasonic propulsion alone or with burst wave lithotripsy was administered by a handheld transducer to awake, unanesthetized subjects. Efficacy outcomes included stone motion, stone passage, and pain relief. Safety outcome was the reporting of associated anticipated or adverse events. Twenty-nine subjects received either ultrasonic propulsion alone (n = 16) or with burst wave lithotripsy bursts (n = 13), and stone motion was observed in 19 (66%). The stone passed in 18 (86%) of the 21 distal ureteral stone cases with at least 2 weeks follow-up in an average of 3.9±4.9 days post-procedure. Fragmentation was observed in 7 of the burst wave lithotripsy cases. All subjects tolerated the procedure with average pain scores (0-10) dropping from 2.1±2.3 to 1.6±2.0 (P = .03). Anticipated events were limited to hematuria on initial urination post-procedure and mild pain. In total, 7 subjects had associated discomfort with only 2.2% (18 of 820) propulsion bursts. This study supports the efficacy and safety of using ultrasonic propulsion and burst wave lithotripsy in awake subjects to reposition and break ureteral stones to relieve pain and facilitate passage.

Fabrication and characterization of row-column addressed pMUT array with monocrystalline PZT thin film toward creating ultrasonic imager

In this study, we fabricated a row-column addressed 2-dimensional piezoelectric micromachined ultrasonic transducer (pMUT) array based on the monocrystalline Pb(Zr, Ti)O3 (Mono PZT)-based thin film, and demonstrated its application as the ultrasound imager. At first, we optimized the island-shaped design as an individual element, and then developed the fabrication process based on the control of the edge shape of an insulative polymer pattern. As a result, the hexagonally arranged arrays with 372 elements at the maximum were fabricated successfully, of which the diameter and pitch were 70 µm and 120 µm, respectively. The resonance frequency, displacement sensitivity, and quality factor in air measured approximately 5.4 MHz, 175 nm/V and 175, respectively. This array exhibited low crosstalk. The actuation of the unaddressed element was less than 10 % of that of the addressed one. In addition, the deviations on the resonance frequencies and displacement sensitivities were as small as only 2 % and 15 %, respectively. Then, the basic acoustic performance in a medium FC-70 was evaluated by using the minimum unit array composed of 5 columns. Also, the transmitting beamforming of a focused ultrasonic burst wave was done by applying driving voltages with a time delay. Finally, an ultrasonic imaging for a metallic object was demonstrated by mechanically scanning the object.

Crack localization in plate-like metallic structures using vibration modulated guided waves

Abstract This paper proposes a method for crack localization in plate-like metallic structures with nonlinear vibration modulated guided waves. A spatially distributed piezoceramic transducer array is used to introduce a low-frequency modal vibration and a high-frequency ultrasonic tone burst into a metallic plate, and the responses are also acquired by the array. Due to the semi-broadband property and similar propagating speed, the nonlinear waves generated from the damage and the linear waves from other structural features overlap both in time and frequency in the acquired response signals. It is difficult to separate them by filtering method, which affects the damage localization result. The conventional pulse inversion technique is extended to extract the nonlinear signals, and then a delay-and-sum imaging method based on the Wigner-Ville distribution is applied to the extracted signals to construct a damage image. The proposed method is experimentally investigated to localize a fatigue crack near a drilled hole in an aluminium plate. The results demonstrate that the fatigue crack is localized accurately and is also distinguished from linear scatters by use of the proposed method.

Investigation of the Effects of Cardiovascular Therapeutic Ultrasound Applied in Female and Male Rats' Hearts of Different Ages.

This study investigates the role of age and sex on the cardiovascular effects of 3.5-MHz pulsed ultrasound (US) in a rat model. Ultrasonic bursts of 2.0-MPa peak rarefactional pressure amplitude (equivalent to an in vitro spatial-peak temporal-peak intensity of ~270 W/cm2 and a mechanical index of 1.1) were delivered in five consecutive 10-s intervals, one interval for each pulse repetition frequency (PRF) (6, 5, 4, 5, and 6 Hz; always the same order) for a total exposure duration of 50 consecutive seconds. Sixty F344 rats were split into 12 groups in a 3 × 2 × 2 factorial design (three ages, male versus female, and US application versus control). This study is the first study on US-induced cardiac effects that contains data across three age groups of rats (premenopause, fertile, and postmenopause) to mimic the fertile and nonfertile human window. US was applied transthoracically, while heart rate, stroke volume, ejection fraction, temperature, and other physiologic parameters were recorded at baseline and after exposure. Significant decreases in cardiac output compared to respective control groups were observed in multiple experimental groups, spanning both females and males. A negative chronotropic effect was observed in young male (~7%) and female (~16%) rats, in five-month-old male (~9%) and female (~15%) rats, and in old rats where the effect was not statistically significant. Younger groups and, to a lesser extent, lower weight groups generally had more significant effects. The pathophysiology of US-induced cardiovascular effects appears to be multifactorial and not strictly related to hormones, menopause, weight, sex, or age, individually.

Ultrasound to facilitate passage of distal ureteral stones

Feasibility of ultrasonic propulsion and burst wave lithotripsy (BWL) to noninvasively reposition distal ureteral stones to facilitate passage and relieve pain was tested. Patients presenting to the clinic or emergency department were recruited. Thirteen subjects underwent ultrasonic propulsion (lower amplitude, longer duration pulses) alone, and 10 subjects also received intermittent BWL (higher amplitude, shorter duration pulses). All participants were awake and underwent a pain assessment pre- and post-procedure. For analysis, subjects were sub-categorized based on whether their stone was acute or chronic (present for ≤10 days or >10 days from their initial ED or symptomatic presentation, respectively). Seventeen subjects were enrolled in the acute study population and 6 subjects were enrolled in the chronic population. Overall, 94% of acute stones passed in an average of 3.4 days post-procedure relative to 54% in 7.5 days in the American Urological Association guidelines. 67% of chronic cases passed stones or fragments, and two surgeries were cancelled. Pain reduction was statistically significant ( p = 0.0215). Adverse events were limited to hematuria on initial urination post-procedure (BWL only, n = 3) and a mild sensation, akin to a pinprick, associated with fewer than 10 of 620 propulsion bursts ( n = 3). [Work supported by NIH-P01-DK04331.]

Measurement of unwanted powder build-ups in manufacturing using high frequency ultrasonic bursts and standing waves reflectance method

This paper proposes a combination of high frequency ultrasonic techniques to characterize non-invasively the thickness of unwanted powder build-ups that occur in pipes and charge hoppers during industrial processes. Three compressed iron oxide powder cakes were reproduced in laboratory in different thicknesses varying from 5 mm to 15 mm. The density and hardness of the samples made in the laboratory were compared to samples that formed in-situ in a charge hopper using time of flight ultrasonic measurements, light optical microscopy, and pycnometer densitometry techniques. The powder build-ups were deposited on a metal plate instrumented with miniaturized ultrasonic sensors operating around the center frequency of 10 MHz. These sensors operated using both the reflection coefficient methodology and a new standing waves approach. The thickness of the powders was measured by correlating the standing wave resonant frequency change to the quantity of powder deposited on the surface. The powder build-ups were also compressed using a pressure up to 15 MPa and the reflection coefficient and the frequency change using the ultrasonic reflectance method were used to decouple the effect of load to the thickness measurement. Build-ups of 5, 10 and 15 mm of thickness were obtained, and the ultrasonic method measured the layer thickness with an accuracy of 10 %.

Overvoltage Protection Circuits for Ultrasonically Powered Implantable Microsystems.

This paper presents a novel overvoltage protection technique for ultrasonically powered microsystems. The proposed idea benefits from voltage-current characteristics of the piezoelectric harvesters, and limits the amplitude of the harvested signal by regulating the current consumption of the system. For this purpose, a low-area low-power overvoltage regulator is proposed, analyzed and simulated in transistor level in standard TSMC 0.18μm CMOS technology occupying a silicon area of 285μm2. Furthermore, to avoid unnecessary power consumption of the overvoltage regulator, it is proposed to take advantage of an ultrasonic burst detection block to deactivate the regulator in the absence of ultrasonic waves. According to our simulation results, the quiescent power consumption of the proposed circuit in the presence and absence of ultrasonic waves are 37 and 3μW respectively, and the minimum phase margin of the negative feedback loop is 68 degree.

Optimal pump excitation frequency for improvement of damage detection by nonlinear vibro acoustic modulation method in a multiple scattering sample

We present a method to systematically optimize nonlinear damage detection in multiple scattering media by the nonlinear Vibro-Acoustic Modulation (VAM) technique. The latter consists here of exciting a medium simultaneously with a high frequency ultrasonic sinusoidal burst and with a low frequency continuous sinusoidal wave. Modulation of the high frequency (probe) by the low frequency (pump) is made possible by the presence of nonlinear scatterers, i.e. cracks, defects. A signal processing technique consisting of a closed loop system drives the automatic adaptation of the pumping frequency, yielding to the optimization of the nonlinear modulation (NM) of the output probing coda signal without a priori information on the medium and the scatterers. The correlation coefficient between a reference output probe signal without the pumping wave and an output modulated probe signal with a pumping wave was considered as our cost function. A multiple scattering solid beam where nonlinear scatterers can be controllably added or removed is designed and tested. The first step of this study is an empirical search of the correlation coefficient dependency on the pumping frequency to verify the performances of the proposed method. Then the implemented optimization algorithm based on genetic algorithm (GA) is used to find automatically the optimal pumping frequency. The obtained optimization results show a good agreement with the empirical study. Moreover, the genetic algorithm allowed to find the optimal pump frequency adapted to each configuration of nonlinear scatterers. This relatively fast search of the optimal nonlinear response could be extended to nonlinear scatterer imaging applications using the information on the resonant modes spatial shapes together with the associated optimal response.

Temporal window of integration estimated by omission in bone-conducted ultrasound

Bone-conducted ultrasound (BCU) can be heard for both normal-hearing and some profoundly deaf individuals. Moreover, amplitude-modulated BCU can transmit the speech signal. These characteristics of BCU provide the possibility of the developing a bone-conducted ultrasonic hearing aid. Previous studies on the perception mechanism of speech-modulated BCU have pointed to the importance of temporal rather than frequency information. In order to elucidate the perception of speech-modulated BCU, further investigation is need concerning the processing of temporal information. The temporal processing of air-conducted audible sounds (ACASs) involves the integration of closely presented sounds into a single information unit. The long-temporal window of integration was estimated approximately 150–200 ms, which contribute to the discrimination of speech sound. The present study investigated the long-temporal integration system for BCU evaluated by stimulus omission using magnetoencephalography.Eight participants with normal hearing took part in this study. Ultrasonic tone burst with the duration of 50 ms and frequency of 30 kHz was used as the standard stimulus and presented with steady onset-to-onset times or stimulus-onset asynchronies (SOAs). In each sequence, the duration of the SOAs were set to 100, 125, 150, 175, 200, or 350 ms. For deviant, tones were randomly omitted from the stimulus train. Definite mismatch fields were elicited by sound omission in the stimulus train with an SOA of 100–150 ms, but weren’t with an SOA of 200 and 350 ms for all participants.We found that stimulus train for BCUs can be integrated within a temporal window of integration with an SOA of 100–150 ms, but are regarded as a separate event when the SOA is 200 or 350 ms in duration. Therefore, we demonstrated that the long-temporal window of integration for BCUs estimated by omission was 150–200 ms, which was similar to that for ACAS (Yabe et al. NeuroReport 8 (1997) 1971–1974 and Psychophysiology. 35 (1998) 615–619). These findings contribute to the elucidation and improvement of the perception of speech-modulated BCU.

Relating speed of sound and echo amplitude with biodiesel manufacture

Biodiesel has a potential not completely exploited as substitute of diesel oil, despite it is known as biodegradable, nontoxic, and has a low-emission profile. The aim of this paper is to propose an ultrasonic method as a tool for real-time monitoring transesterification reactions by using low-power ultrasound based on a pulse/echo scheme. Two catalytic routes were tested, both using degummed soybean oil as source and KOH as catalyser. The difference between catalytic routes was the type of alcohol used (methanol and ethanol). Three different reaction times were studied: 10, 20, and 30min. Low power (less than 100mW) ultrasonic time-gated bursts were applied to the reactional media at 1MHz. The eco was measured during the reaction, and small amounts of the reaction media were collected every 2min for chemical analysis. Time of flight and echo waveform amplitude were the ultrasonic parameter of interest. The amplitude of the ultrasonic waveform was related with the variation of the ethanol-transesterification reaction rate and could help in qualitatively monitoring that reaction. Furthermore, density measurements where consistent with the variations observed on time of flight, confirming the possibility of monitoring the reaction using ultrasonic parameters. The behaviour of the ultrasonic parameters varied depending on the alcohol and the presence or not of heating during the reaction. As a common rule, the stabilization of the ultrasonic parameters indicates that the maximum yield for each catalytic route is achieved, indicating that the reaction should be stopped for maximum energy efficiency. Results disclose that the proposed method is a feasible way to monitor the reactions of biodiesel during its production, in real time, and with relatively low-cost equipment. Further development shall be done to use it in industrial scale, mainly regarding the ultrasound power and frequency to be employed.

Epitaxial PMnN-PZT/Si MEMS ultrasonic rangefinder with 2 m range at 1 V drive

In this study, we successfully developed a high signal-to-noise ratio (SNR) rangefinder based on a piezoelectric micromachined ultrasonic transducer (pMUT). A c-axis-oriented Pb(Mn1/3,Nb2/3)O3-Pb(Zr,Ti)O3 (PMnN-PZT) epitaxial thin film was employed as a piezoelectric transducer considering its outstanding figures-of-merit for SNR, due to the high piezoelectric coefficient and small relative permittivity (typical values: e31,f=−14C/m2, εr=200–300). The pMUTs was based on an epitaxial PMnN-PZT/Si diaphragm structure and prototyped from a SOI substrate; its rangefinding ability was evaluated with a pair of devices, specifically, transmitter and receiver, respectively. As a result, the maximum range was estimated to be over 2m at a low actuating voltage of 1Vp-p, when 12dB was set as the threshold SNR. The energy consumption of the transmitter was as small as ∼5nJ for the generation of a 50-cycle ultrasonic burst. The noise analysis of the receiver’s charge amplifier circuit indicated that this system could be improved by the optimization of bandwidth and by eliminating external noise. We believe that this high performance pMUT rangefinder will be utilized in various applications of consumer electronics or as an alternative to the bulk piezoelectric ceramic rangefinder in the near future.

Effect of Stone Size and Composition on Ultrasonic Propulsion Ex Vivo

To evaluate in more detail the effectiveness of a new designed more efficient ultrasonic propulsion for large stones and specific stone compositions in a tissue phantom model. In the first clinical trial of noninvasive ultrasonic propulsion, urinary stones of unknown compositions and sizes up to 10 mm were successfully repositioned. The study included 8- to 12-mm stones of 4 different primary compositions (calcium oxalate monohydrate, ammonium acid urate, calcium phosphate, and struvite) and a renal calyx phantom consisting of a 12 mm × 30 mm well in a 10-cm block of tissue-mimicking material. Primary outcome was the number of times a stone was expelled over 10 attempts, with ultrasonic propulsion burst duration varying from 0.5 seconds to 5 seconds. Overall success rate at expelling stones was 95%. All calcium oxalate monohydrate and ammonium acid urate stones were expelled 100% of the time. The largest stone (12 mm) became lodged within the 12-mm phantom calyx 25% of the time regardless of the burst duration. With the 0.5-second burst, there was insufficient energy to expel the heaviest stone (0.88 g), but there was sufficient energy at the longer burst durations. With a single burst, ultrasonic propulsion successfully moved most stones at least 3 cm and, regardless of size or composition, expelled them from the calyx. Ultrasonic propulsion is limited to the stones smaller than the calyceal space, and for each burst duration, related to maximum stone mass.

The Negative Chronotropic Effect in Rat Heart Stimulated by Ultrasonic Pulses: Role of Sex and Age.

The goal of this study is to investigate the role of sex and age of the negative chronotropic effect after exposure of 3.5-MHz pulsed ultrasound (US) to the rat heart. Forty F344 rats were exposed transthoracically to ultrasonic pulses at a duty factor of approximately 1.0% at 2.0-MPa peak rarefactional pressure amplitude. The transthoracic ultrasonic bursts were delivered consecutively in five 10-s intervals, that is, 10 s of 6-Hz pulse repetition frequency (PRF), 10 s of 5-Hz PRF, 10 s of 4-Hz PRF, 10 s of 5-Hz PRF, and 10 s of 6-Hz, for a 50-s total exposure duration. The rats were divided into 8 groups (n = 5 each): US young male, control young male, US young female, control young female, US old male, control old male, US old female, and control old female. Two-way ANOVA for repeated measures was used to compare heart rate, cardiac output, arterial pressure, and other hemodynamic values (baseline) before and after US stimulation. Sex versus age versus US interaction was detected for heart rate. Cardiac output showed an age effect, and ejection fraction showed age and US effects. The arterial pressure showed a sex effect. A negative chronotropic effect (∼30% decrease in heart rate) was observed for young female rats. An hypothesis is that the US effect is weight (menopause) dependent, because the young (premenopausal) female rats weighed approximately 40 to 60% less than other groups of rats. It is likely that the ovarian hormones are responsible for different US-induced cardiac bioeffects in different ages and sexes.

Enhancement of Ultrasonic De-Icing via Tone Burst Excitation

Previous ultrasonic de-icing research on rotorcraft has demonstrated that applying multifrequency burst actuation schemes has increased the ice protection area coverage of the system. The physical mechanisms responsible for this increase in de-icing performance are modeled using finite elements and tested using both freezer ice and impact ice in the Adverse Environment Rotor Test Stand facility at the Pennsylvania State University. Freezer ice was tested using a 0.035-in.-thick (0.889-mm-thick) titanium grade 2 plate. Impact ice testing was conducted using a 0.035-in.-thick (0.889-mm-thick) stainless steel NACA 0015 airfoil structure (16 in. or 40.64 cm chord). It is proven that the increase in ice shedding area when using multifrequency tone bursts is due to the transient nature of the excitation and not the multimode control of the structure at varying frequencies surrounding the resonance of the structure. During bench-top testing using freezer ice, ultrasonic burst actuation techniques that exploit transient vibrations showed to increase the de-icing performance (as quantified by the ice shedding area) by a factor of 4 when compared to continuous actuation methods. The benefits of tone burst actuation were as large as 10 times that of continuous frequency actuation when testing rotor impact ice affected by centrifugal loads.

Ultrasonic Fluid Level Measuring Device

Accurate measurement of fluid level is very vital both in industrial and consumer market. Ultrasonic technology is one of the solutions used by the industry. However, an optimized balance between cost and features are a must for almost all target applications. The ultrasonic level measurement is used mainly when a non-contact measurement is required. Precise measurement of low-range distance (level) is the main objective for this project. This device can measure level in the range of 0.02m to 4m with an accuracy of 1cm. This measuring system is based on ultrasonic sound utilizing an Atmega328P low-power microcontroller. The system transmits a burst of ultrasonic sound waves towards the subject and then receives the corresponding echo. An HC-SR04 ultrasonic Module is used to both generate and detect the ultrasound required for level computation. The time taken for the ultrasonic burst to travel the distance from the system to the subject and back to the system is accurately measured. This level is displayed on an alphanumeric LCD with an accuracy of ± 2.5cm. The minimum depth that this system can measure is 2cm and is limited by the transmitter's transducer settling-time. The maximum height that can be measured is 4 meters. The amplitude of the echo depends on the reflecting material, shape, and size. Sound-absorbing targets such as carpets and reflecting surfaces less than two square feet in area reflect poorly. The maximum measurable range is lower for such subjects. If the amplitude of the echo received by the system is so low that it is not detectable by the ultrasonic module, the system goes out of range. This is indicated by displaying the error message OOR (Out-of-Range) on the LCD.