The explosive growth in data-centric artificial intelligence related applications necessitates a radical departure from traditional von Neumann computing systems, which involve separate processing ...and memory units. Computational memory is one such approach where certain tasks are performed in place in the memory itself. This is enabled by the physical attributes and state dynamics of the memory devices. Naturally, memory plays a central role in this computing paradigm for which emerging post-CMOS, non-volatile memory devices based on resistance-based information storage are particularly well suited. Phase-change memory is arguably the most advanced resistive memory technology and in this article we present a comprehensive review of in-memory computing using phase-change memory devices.
The aim of the study was to investigate decolorization of Rhodamine B (RB) in aqueous solution using ultrasonic degradation. The results showed that decolorization follows pseudo-first-order reaction ...kinetics. The apparent reaction rate constant (
k
ap) was found to increase with decreasing pH and decreases with increasing initial RB concentration. Power density was very important parameter and increasing it causes a considerable increase of removal efficiency. UV–vis spectral changes of RB indicate that in the sonolysis of RB, the cleavage of aromatic chromophore ring structure and the
N-deethylation take place, but decomposition of aromatic structure is predominant.
This research paper introduces a novel three-dimensional autonomous system, whose dynamics support periodic and chaotic butterfly attractors as certain parameters vary. A special case of this system, ...exhibiting reflectional symmetry, is amenable to analytical and numerical analysis. Qualitative properties of the new chaotic system are discussed in detail. Adaptive control laws are derived to achieve global chaotic synchronization of the new chaotic system with unknown parameters. Furthermore, a novel electronic circuit realization of the new chaotic system is presented, examined and realized using Orcad-PSpice program and physical components. The proposed novel butterfly chaotic attractor is very useful for the deliberate generation of chaos in applications.
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•We introduce a novel chaotic system whose dynamics support butterfly attractors.•Qualitative properties of the novel chaotic system are discussed in detail.•Adaptive control laws are derived to achieve global chaos synchronization.•A novel electronic circuit the new chaotic system is designed and realized.•We show a good qualitative agreement between the simulations and the experiments.
•High-speed camera technique is applied to investigate the spark-charge bubble behaviors.•High-speed jet is proved to be the one of most important factors to cause cavitation erosion.•The effect of ...boundary conditions on the bubble dynamics is systematically investigated.
The objective of this paper is to apply experimental methods to investigate the dynamics of spark-induced bubbles in the vicinity of the elastic and rigid boundary. In the experiment, the temporal evolution of the bubble is recorded by the high-speed camera at the 25,000 frames per second, as well as corresponding data such as normalized collapse position, the time of bubble collapse, and the velocity of the high-speed liquid jet. Results are presented for a single bubble generated over the elastic and rigid plates, under a wide range of normalized standoff distance from 0.5 to 3.0. The results show that the high-speed jet emitted by non-spherical bubble collapse near the boundary is one of the important factors to cause the destructive erosion pit. With the increase of the standoff distance, the expansion, shrink, jet formation, and rebound of the bubbles vary evidently adjacent to the different boundary conditions. Compared with the rigid boundary cases, the normalized first collapsed position and the time of bubble collapse are much smaller near the elastic boundary. The formation of the high-speed liquid jet in the neighborhood of the elastic/rigid boundary is founded in two different mechanisms. Furthermore, the normalized maximum velocity near the rigid plate is always larger than that near the elastic plate.
Indoor location and positioning systems (ILPS) are used to locate and track people, as well as mobile and/or connected targets, such as robots or smartphones, not only inside buildings with a lack of ...global navigation satellite systems (GNSS) signals but also in constrained outdoor situations with reduced coverage. Indoor positioning applications and their interest are growing in certain environments, such as commercial centers, airports, hospitals or factories. Several sensory technologies have already been applied to indoor positioning systems, where ultrasounds are a common solution due to its low cost and simplicity. This work proposes a 3D ultrasonic local positioning system (ULPS), based on a set of three asynchronous ultrasonic beacon units, capable of transmitting coded signals independently, and on a 3D mobile receiver prototype. The proposal is based on the aforementioned beacon unit, which consists of five ultrasonic transmitters oriented towards the same coverage area and has already been proven in 2D positioning by applying hyperbolic trilateration. Since there are three beacon units available, the final position is obtained by merging the partial results from each unit, implementing a minimum likelihood estimation (MLE) fusion algorithm. The approach has been characterized, and experimentally verified, trying to maximize the coverage zone, at least for typical sizes in most common public rooms and halls. The proposal has achieved a positioning accuracy below decimeters for 90% of the cases in the zone where the three ultrasonic beacon units are available, whereas these accuracies can degrade above decimeters according to whether the coverage from one or more beacon units is missing. The experimental workspace covers a large volume, where tests have been carried out at points placed in two different horizontal planes.
Purpose:
Previous studies demonstrated that thermoacoustic imaging (TAI) has great potential for breast tumor detection. However, large field of view (FOV) imaging remains a long‐standing challenge ...for three‐dimensional (3D) breast tumor localization. Here, the authors propose a practical TAI system for noninvasive 3D localization of breast tumors with large FOV through the use of ultrashort microwave pulse (USMP).
Methods:
A USMP generator was employed for TAI. The energy density required for quality imaging and the corresponding microwave‐to‐acoustic conversion efficiency were compared with that of conventional TAI. The microwave energy distribution, imaging depth, resolution, and 3D imaging capabilities were then investigated. Finally, a breast phantom embedded with a laboratory‐grown tumor was imaged to evaluate the FOV performance of the USMP TAI system, under a simulated clinical situation.
Results:
A radiation energy density equivalent to just 1.6%–2.2% of that for conventional submicrosecond microwave TAI was sufficient to obtain a thermoacoustic signal with the required signal‐to‐noise ratio. This result clearly demonstrated a significantly higher microwave‐to‐acoustic conversion efficiency of USMP TAI compared to that of conventional TAI. The USMP TAI system achieved 61 mm imaging depth and 12 × 12 cm2 microwave radiation area. The volumetric image of a copper target measured at depth of 4–6 cm matched well with the actual shape and the resolution reaches 230 μm. The TAI of the breast phantom was precisely localized to an accuracy of 0.1 cm over an 8 × 8 cm2 FOV.
Conclusions:
The experimental results demonstrated that the USMP TAI system offered significant potential for noninvasive clinical detection and 3D localization of deep breast tumors, with low microwave radiation dose and high spatial resolution over a sufficiently large FOV.
Picosecond ultrasonics has seen wide application in the investigation of interfaces in semiconductors and 3D imaging in biological systems. Shear ultrasonic waves are important for elastic constant ...and grain orientation measurement in ceramic materials. In this study, we investigate the impact of grain orientation and material's elastic properties on the generation efficiency of shear waves by mode conversion at a transducer thin film/substrate interface. The solution of acoustic wave equations suggests that crystal grain orientation has a strong impact on the generated shear wave amplitude. This dependence is found to be closely related to the magnitude of longitudinal component of wave displacements. The applicability of analytical model is validated by the experimental results from time‐domain Brillouin scattering. Moreover, material properties determine acoustic wave amplitudes based on the acoustic mismatch model and, particularly, large elastic anisotropy defined by Zener ratio favors strong shear waves. In the light of this analysis, several recommendations on suitable grain orientations and film materials are made to facilitate shear wave detection.
Magnetic targeting of microbubbles functionalized with superparamagnetic nanoparticles has been demonstrated previously for diagnostic (B-mode) ultrasound imaging and shown to enhance gene delivery ...in vitro and in vivo. In the present work, passive acoustic mapping (PAM) was used to investigate the potential of magnetic microbubbles for localizing and enhancing cavitation activity under focused ultrasound. Suspensions of magnetic microbubbles consisting of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), air and 10 nm diameter iron oxide nanoparticles were injected into a tissue mimicking phantom at different flow velocities (from 0 to 50 mm s(-1)) with or without an applied magnetic field. Microbubbles were excited using a 500 kHz single element focused transducer at peak negative focal pressures of 0.1-1.0 MPa, while a 64 channel imaging array passively recorded their acoustic emissions. Magnetic localization of microbubble-induced cavitation activity was successfully achieved and could be resolved using PAM as a shift in the spatial distribution and increases in the intensity and sustainability of cavitation activity under the influence of a magnetic field. Under flow conditions at shear rates of up to 100 s(-1) targeting efficacy was maintained. Application of a magnetic field was shown to consistently increase the energy of cavitation emissions by a factor of 2-5 times over the duration of exposures compared to the case without targeting, which was approximately equivalent to doubling the injected microbubble dose. These results suggest that magnetic targeting could be used to localize and increase the concentration of microbubbles and hence cavitation activity for a given systemic dose of microbubbles or ultrasound intensity.
The ability to accurately measure body or carcass composition is important for performance testing, grading and finally selection or payment of meat-producing animals. Advances especially in ...non-invasive techniques are mainly based on the development of electronic and computer-driven methods in order to provide objective phenotypic data. The preference for a specific technique depends on the target animal species or carcass, combined with technical and practical aspects such as accuracy, reliability, cost, portability, speed, ease of use, safety and for in vivo measurements the need for fixation or sedation. The techniques rely on specific device-driven signals, which interact with tissues in the body or carcass at the atomic or molecular level, resulting in secondary or attenuated signals detected by the instruments and analyzed quantitatively. The electromagnetic signal produced by the instrument may originate from mechanical energy such as sound waves (ultrasound – US), ‘photon’ radiation (X-ray-computed tomography – CT, dual-energy X-ray absorptiometry – DXA) or radio frequency waves (magnetic resonance imaging – MRI). The signals detected by the corresponding instruments are processed to measure, for example, tissue depths, areas, volumes or distributions of fat, muscle (water, protein) and partly bone or bone mineral. Among the above techniques, CT is the most accurate one followed by MRI and DXA, whereas US can be used for all sizes of farm animal species even under field conditions. CT, MRI and US can provide volume data, whereas only DXA delivers immediate whole-body composition results without (2D) image manipulation. A combination of simple US and more expensive CT, MRI or DXA might be applied for farm animal selection programs in a stepwise approach.
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