High Frequency Elements Research Articles

Numerical Simulation and Experimental Verification of Electric–Acoustic Conversion Property of Tangentially Polarized Thin Cylindrical Transducer

In solving piezoelectric equations of motion, we established an electric–acoustic equivalent circuit of tangentially polarized thin cylindrical transducers and derived analytical expressions of the electric-acoustic response from the harmonic driving-voltage excitation. To experimentally verify the findings, we manufactured a parallel electric-acoustic transmission network for transducers excited by multifrequency driving signals. We found that the tangentially polarized thin cylindrical transducers achieved a much higher electric-acoustic conversion efficiency than the radially polarized thin cylindrical transducers. The electric-acoustic impulse response of the transducers consisted of a direct-current damping with lower-frequency components, a damping oscillation with higher-frequency elements, and a higher resonant frequency of the transducer over its center frequency. The characteristics of radiated acoustic signals included contributions from the geometrical shape and size of the transducer, the physical parameters of piezoelectric material, the type of driving-voltage signals, and the polarization mode of the transducers. In comparison, our theoretical predictions are in good agreement with experimental observations. It is plausible that using the tangentially polarized thin cylindrical transducers as sensors in the acoustic-logging tool may significantly improve the signal-to-noise ratio of the measured acoustic-logging signals.

Development of Dual-Frequency PMUT Arrays Based on Thin Ceramic PZT for Endoscopic Photoacoustic Imaging.

This paper presents a dual-frequency piezoelectric micromachined ultrasonic transducer (pMUT) array based on thin ceramic PZT for endoscopic photoacoustic imaging (PAI) applications. With a chip size of 7 × 7 mm2, the pMUT array consists of 256 elements, half of which have a lower resonant frequency of 1.2 MHz and the other half have a higher resonant frequency of 3.4 MHz. Ceramic PZT, with outstanding piezoelectric coefficients, has been successfully thinned down to a thickness of only 4 μ by using wafer bonding and chemical mechanical polishing (CMP) techniques and employed as the piezoelectric layer of the pMUT elements. The diaphragm diameters of the lower-frequency and higher-frequency elements are 220 μm and 120 μm, respectively. The design methodology, multiphysics modeling, fabrication process, and characterization of the pMUTs are presented in detail. The fabricated pMUT array has been fully characterized via electrical, mechanical, and acoustic measurements. The measured maximum responsivities of the lower- and higher- frequency elements reach 110 nm/V and 30 nm/V at their respective resonances. The measured cross-couplings of the lower-frequency elements and higher-frequency elements are about 9% and 5%, respectively. Furthermore, PAI experiments with pencil leads embedded into an agar phantom have been conducted, which clearly shows the advantages of using dual-frequency pMUT arrays to provide comprehensive photoacoustic images with high spatial resolution and large signal-to-noise ratio simultaneously.

Assessing Visual Fatigue of Welding Mask Wearers Through Infrared Imaging-Based Ocular Feature Analysis

Electronic devices have become indispensable to individuals today. Looking at these electronic displays for extended periods causes visual fatigue. Herein, we propose three metrics for objective and quantitative measurement of visual fatigue: blink frequency, blink duration, and pupil accommodation speed. After taking eye images using an infrared camera, binarization and contour detection were performed to localize the pupil. The diameter of the localized pupil region, defined as pupil size, was calculated based on the number of black pixels in the pupil region. The blink frequency, blink duration, and pupil accommodation speed were measured by analyzing successive pupil sizes. To obtain pupil accommodation speed, inflection points were extracted after removing high frequency elements in the frequency domain. After inducing visual stimulation on 10 participants by welding sparks for 30 minutes, two incremental fatigue periods were observed. Blink frequency and duration increased in a similar manner, and pupil accommodation speed decreased in the sections. Therefore, it can be confirmed that as the degree of visual fatigue increases, blink frequency and duration increase, and pupil accommodation speed decreases. Moreover, we confirmed that when eyes become tired, the tendency of blink frequency and duration is opposite to that of the pupil accommodation speed.

Chaotic study on a multibody interacting particle system with trajectory of variable curvature radius

Multibody interacting particle system is one of the most important driven-diffusive systems, which can well describe stochastic dynamics of self-driven particles unidirectionally updating along one-dimensional discrete lattices controlled by hard-core exclusions. Such determined nonlinear dynamic system shows the chaos, a complicated motion that is similar to random and can’t determine future states according to given initial conditions. Derived from the study of randomness in the framework of determinism, chaos effectively unifies determinacy and randomness of nonlinear physics, which also embodies the randomness and uncertainty of multi-body particle motions. Besides, chaos often presents complex ordered phenomena like aperiodic ordered motion state etc., which indicates it’s a stable coordination of local random and global mode. Different with previous work, a mesoscopic multibody interacting particle system considering the trajectory of variable curvature radius is proposed, which is more reliable to depict true driven-diffusive systems. Nonlinear dynamical master equations are established. Linear and nonlinear stability analyses are performed to test system robustness, which lead to linear stable region, metastable region, unstable region, triangular wave, solitary wave and kink-antikink wave. Complete numerical simulations under quantitatively changing characteristic order parameters are performed to reveal intrinsic chaotic dynamics mechanisms. By comparing fruitful chaotic patterns, double periodic convergence in stable limit cycles is observed due to attractors folding. System states tend to be limit cycles with the passage of time. The longer time is, the higher density is near attractors. The number of main components of attractors and the shape of them are found to drastically change with these parameters. Hereafter, the chaotic formation mechanism is explained by performing Fourier spectrums analyses. High and low frequency elements are obtained, whose module lengths are found to change periodically with time and nonperiodically with space. Our results show the sensitivity of the chaotic system to initial conditions, which mean slight changes of initial states in one part of system can lead to disproportionate consequences in other parts. The sensitivity is directly related to uncertainty and unpredictability. Moreover, calculations also show that three kinds of attractors (namely, point attractor, limit-cycle attractor and strange attractor) exist in the proposed chaotic system, which control particle motions. The first two attractors are convergence attractors playing a limiting role, which lead to static and balanced features of system. Oppositely, strange attractor makes the system deviate from regions of convergent attractors and creates unpredictability by inducing the vitality of the system and turning it into a non-preset mode. Furthermore, interactions between convergence attractors and strange attractors trigger such locally fruitful modes. This work will be helpful to understand mesoscopic dynamics, stochastic dynamics and non-equilibrium dynamical behaviors of multibody interacting particle systems.

User-friendly cross-directional MPC tuning for uncertain multiple-array paper-making processes

The cross-directional model predictive control (CD-MPC) tuning problem is investigated for multiple-array paper-making process with parametric uncertainty. A systematic spatial tuning method is proposed to tune the penalty matrices such that the harmful high frequency elements in each actuator profile can be eliminated. A multivariable temporal filter is employed to adjust the output references, and a temporal tuning algorithm is developed for the filter parameters to achieve the pre-specified 2σ performance indices. The computational time of the proposed methods is reduced via event-based sampling strategy. The effectiveness of the techniques is shown via a CD system from paper-making industry.

High fructose diet induces early mortality via autophagy factors accumulation in the rostral ventrolateral medulla as ameliorated by pioglitazone

High fructose ingestion enhances mortality which has been linked to autonomic dysregulation. However, the underlying mechanisms are still largely unknown. In the present study, we demonstrated that 3 months of high fructose diet (HFD) ingestion induced mortality in 18-week-old Wistar Kyoto rats (WKY) during anesthesia. Concurrently, the low frequency (LF) and the high frequency (HF) elements of the power spectral analyses of SBP were increased. Of note, the decreased ratio of LF and HF (LF/HF), an index of sympathetic and parasympathetic balance, suggested an autonomic imbalance. In the rostral ventrolateral medulla (RVLM), a center of sympathetic outflow, the levels of presynaptic (synaptophysin) and postsynaptic (postsynaptic density protein 95 and phospho-Ca2+/calmodulin-dependent protein kinase II) proteins were increased. The down-regulation of insulin receptor β and insulin receptor substrate 1 suggested the status of insulin desensitization. Moreover, the up-regulation of AMP-activated protein kinase and sirtuin 1 suggested the enhancement of energy sensing to activate autophagy. Simultaneously, the accumulations of Beclin-1, ATG12 and LC3B were increased in RVLM. Pioglitazone (PIO), an insulin sensitizer, effectively relieved the accumulation of Beclin-1 and ATG12 as well as the synaptic proteins synchronized with the reverses of insulin and energy sensing signals. Moreover, the autonomic dysregulation and anesthesia-associated mortality were intervened. Together, these results suggested that the HFD-induced, anesthesia-associated mortality rate was related to the autonomic abnormality derived from the RVLM synaptic alteration, which is strongly related to insulin desensitization-associated autophagy. PIO intervened the HFD-induced mortality via reversal of the above-mentioned molecules.

Individual entrenchment vs. community-wide conventionalization of contact features in L2 Basque speakers’ individual styles

AbstractThis article examines individual variation of contact features in the speech patterns of four L2 Basque speakers. The individual styles are examined through the concepts of individual entrenchment and community-wide conventionalization to bridge the gap between linguistic variation and change at the individual and social levels. All the informants speak Spanish as their L1. They have acquired Basque in classroom contexts, and they belong to the same macrosociolinguistic categories. Yet their patterns of using the language contact between standard Basque, vernacular Basque dialects and Spanish as a resource in creating individual speech styles differ considerably, reflecting their language attitudes and their personal experience. Nevertheless, there are conventionalized patterns that emerge out of this diversity: All speakers use the standard Basque as the base language, and none of them adopts of vernacular variety as a whole. The Spanish resources seem to be used mainly for pragmatic and stylistic functions, whereas the features of vernacular Basque that the speakers have adopted as part of their individual styles are high frequency elements of core grammar.

Cable shared dual-frequency catheter for intravascular ultrasound.

This study proposes a catheter consisting of dual-frequency transducer for intravascular ultrasound. Both ultrasonic elements with different frequencies were connected to one coaxial cable to make the connection simple. The aperture size of the ultrasound elements were 0.4×0.6 mm2 and 0.3×0.4 mm2 for the low frequency element and high frequency element, respectively. The center frequency and bandwidth of the fabricated low frequency transducer were 33.8 MHz and 49.3%, respectively. Meanwhile, the center frequency and bandwidth of the high frequency transducer were 80.6 MHz and 50.3%, respectively. Imaging evaluations of wire phantom, tissue phantom and vessel tissue demonstrated good imaging capability of the dual-frequency catheter. The spatial resolution are 19 μm axially and 128 μm laterally for the high frequency transducer, and 37 μm axially and 199 μm laterally for the low frequency transducer. Band-pass filters were designed to separate the mixed echo signals. After filtering, the images from different ultrasound elements can be successfully identified, indicating the feasibility of the proposed cable shared dual-frequency imaging strategy. The proposed method has simple structure, good imaging resolution, and large penetration depth, showing good application prospect for intravascular ultrasound.

Local energy match based non-sub sampled contourlet Transform for multi modal medical image fusion

Image processing technology requires moreover the full image or the part of image which is to be processed from the user’s point of view like the radius of object etc. The main purpose of fusion is to diminish dissimilar error between the fused image and the input images. With respect to the medical diagnosis, the edges and outlines of the concerned objects is more important than extra information. So preserving the edge features of the image is worth for investigating the image fusion. The image with higher contrast contains more edge-like features. Here we propose a new medical image fusion scheme namely Local Energy Match NSCT based on discrete contourlet transformation, which is constructive to give the details of curve edges. It is used to progress the edge information of fused image by dropping the distortion. This transformation lead to crumbling of multimodal image addicted to finer and coarser details and finest details will be decayed into unusual resolution in dissimilar orientation. The input multimodal images namely CT and MRI images are first transformed by Non Sub sampled Contourlet Transformation (NSCT) which decomposes the image into low frequency and high frequency elements. In our system, the Low frequency coefficient of the image is fused by image averaging and Gabor filter bank algorithm. The processed High frequency coefficients of the image are fused by image averaging and gradient based fusion algorithm. Then the fused image is obtained by inverse NSCT with local energy match based coefficients. To evaluate the image fusion accuracy, Peak Signal to Noise Ratio (PSNR), Root Mean Square Error (RMSE) and Correlation Coefficient parameters are used in this work .

Wheat ear counting in-field conditions: high throughput and low-cost approach using RGB images

BackgroundThe number of ears per unit ground area (ear density) is one of the main agronomic yield components in determining grain yield in wheat. A fast evaluation of this attribute may contribute to monitoring the efficiency of crop management practices, to an early prediction of grain yield or as a phenotyping trait in breeding programs. Currently the number of ears is counted manually, which is time consuming. Moreover, there is no single standardized protocol for counting the ears. An automatic ear-counting algorithm is proposed to estimate ear density under field conditions based on zenithal color digital images taken from above the crop in natural light conditions. Field trials were carried out at two sites in Spain during the 2014/2015 crop season on a set of 24 varieties of durum wheat with two growing conditions per site. The algorithm for counting uses three steps: (1) a Laplacian frequency filter chosen to remove low and high frequency elements appearing in an image, (2) a Median filter to reduce high noise still present around the ears and (3) segmentation using Find Maxima to segment local peaks and determine the ear count within the image.ResultsThe results demonstrate high success rate (higher than 90%) between the algorithm counts and the manual (image-based) ear counts, and precision, with a low standard deviation (around 5%). The relationships between algorithm ear counts and grain yield was also significant and greater than the correlation with manual (field-based) ear counts. In this approach, results demonstrate that automatic ear counting performed on data captured around anthesis correlated better with grain yield than with images captured at later stages when the low performance of ear counting at late grain filling stages was associated with the loss of contrast between canopy and ears.ConclusionsDeveloping robust, low-cost and efficient field methods to assess wheat ear density, as a major agronomic component of yield, is highly relevant for phenotyping efforts towards increases in grain yield. Although the phenological stage of measurements is important, the robust image analysis algorithm presented here appears to be amenable from aerial or other automated platforms.

Classification of alzheimer's disease subjects from MRI using fuzzy neural network with feature extraction using discrete wavelet transform

Alzheimer's Disease (AD) is a kind of dementia which is tricky to diagnose in accordance with clinical observations. Detection of Alzheimer’s diseases over brain Magnetic Resonance Imaging (MRI) data is main concern in the neurosciences. Traditional assessment of functional image scans typically relies on manual reorientation, visual reading and semi quantitative investigation of certain sections of the brain. Here, proposed Fuzzy Neural Network (FNN) scheme for the purpose of automated multiclass diagnosis of Dementia, in accordance with classification of MRI of human brain. During the initial stage of the work pre-processing is done to get rid of noises. The pre-processing and enhancement scheme includes two steps; initially the removal of film artifacts, for instance, labels and X-ray marks are eliminated from the MRI by means of tracking algorithm. Then, the elimination of high frequency elements by means of Ant Colony based Optimization (ACO) scheme. 2D histogram signal is obtained from preprocessed MR images of brain and subsequently further feature extraction is done through Discrete Wavelet Transform (DWT). This makes use of first few DWT coefficients as features and utilized for the purpose of classification by means of FNN. The features consequently derived are employed for the purpose of training a Fuzzy Neural Network (FNN) to classify features into three classes like Alzheimer’s, Mild Alzheimer's and Huntington's disease. The experimental result shows that the proposed method classification accuracy performance is better than other classification approaches.

Wavelet Transform Based Image Interpolation Using PBP Cubic and Hybrid Filter

In this paper, a new wavelet based image interpolation algorithm using pixel-by-pixel (PBP) cubic image interpolation and hybrid filter is proposed for images which include many mid and high frequency elements. There is much important information in frequency bands. Because conventional interpolation techniques have blurring or blocking effects, the quality of interpolated remote sensing images is not good over that of standard test images. The proposed interpolation technique uses PBP, DWT and hybrid filter to address these problems preserving thin lines and edges information. Simulation result shows that the proposed technique outperforms the conventional techniques in terms of PSNR.

Design and realization of a novel nonplanar dual-polarized log-periodic dipole array for 1-13 GHz

A feasible and low cost approach to implement a nonplanar dual-polarized log-periodic dipole array antenna using printed circuit board (PCB) technology is proposed. The proposed antenna utilizes a very short transition from a coaxial cable to a balanced twin-lead transmission line to realize an ultrawide bandwidth balun, and has two distinct scaling factor values for high and low frequency elements. A prototype of the antenna operating over the frequency range of 1–13 GHz was designed, fabricated, and tested. An average gain of 7 dBi is obtained. Measured VSWR, cross-polarization and front-to-back ratio are better than 2.6, −16 dB, and 22 dB, respectively.

Realtime Super Resolution for 4K/8K with Nonlinear Signal Processing

The 8K system is intended to be the ultimate high-resolution broadcasting system. However, 8K equipment is still under development, and there will be a lack of 8K content once broadcasting begins. It would thus be very useful if 4K content could be converted to a sufficient resolution level to be viewed on 8K systems. Conventional upconverters, from standard-definition television to high-definition television, change the video format with interpolation technology and enhancers. They cannot create higher frequency elements than those of the original content. The same problem affects upconverted 8K content; simply upconverting 4K to 8K does not produce high-resolution 8K content. This paper describes a 4K-to-8K upconverter that uses a novel form of super resolution (SR) technology. The SR technology creates frequency elements that are higher than those of the original 4K content. It can even create elements above the Nyquist frequency, which had been considered a theoretical limitation. The 4K-to-8K upconverter can create content with the same resolution as that of an 8K camera operated in realtime.

Secure and Robust Two-Phase Image Authentication

A novel two-phase robust content-based image authentication scheme is introduced. The proposed scheme is constructed based on a combination of hard and soft authentication using two existing generic approximate message authentication codes (AMACs). The AMACs combine error- correcting codes with cryptographic primitives such as message authentication codes and symmetric encryption algorithms. The message authentication codes are used for hard authentication, whereas the error-correcting codes introduce a certain degree of robustness in authentication. This is achieved by correcting minor unintentional modifications as a result of common image processing operations such as quantization , compression , and noise addition. The two-phase image authentication scheme verifies the authenticity of an image in two phases. The low frequency elements of the image in a transform domain are subjected to the first phase while some higher frequency elements are left to the second phase if the first phase succeeds. The proposed scheme tolerates common content- preserving modifications in an image but can discriminate intentional modifications affecting the image content. Mathematical bounds for the accuracy and the security level of the proposed approach are estimated and the performance is compared with some other well-known schemes in the literature. The results demonstrate that the proposed scheme shows high discriminating capability and can detect different types of meaningful forgery attacks on images while preserving the robustness. It also outperforms the benchmark image authentication schemes in terms of tradeoff between robustness and fragility.

Dual-element needle transducer for intravascular ultrasound imaging.

A dual-element needle transducer for intravascular ultrasound imaging has been developed. A low-frequency element and a high-frequency element were integrated into one device to obtain images which conveyed both low- and high-frequency information from a single scan. The low-frequency element with a center frequency of 48MHz was fabricated from the single crystal form of lead magnesium niobate-lead titanate solid solution with two matching layers (MLs) and the high frequency element with a center frequency of 152MHz was fabricated from lithium niobate with one ML. The measured axial and lateral resolutions were 27 and [Formula: see text], respectively, for the low-frequency element, and 14 and [Formula: see text], respectively, for the high-frequency element. The performance of the dual-element needle transducer was validated by imaging a tissue-mimicking phantom with lesion-mimicking area, and ex vivo rabbit aortas in water and rabbit whole blood. The results suggest that a low-frequency element effectively provides depth resolved images of the whole vessel and its adjacent tissue, and a high-frequency element visualizes detailed structure near the surface of the lumen wall in the presence of blood within the lumen. The advantages of a dual-element approach for intravascular imaging are also discussed.

Research and Analysis on Rock Acoustic Emission Wave Characteristics

Analyzing wave behavior on acoustic emission laboratory tests from relationship between stress and AE rate , the rock AE signal wave in laboratory is decomposed into high and low frequency elements. Analysis and compare with the details elements include, the approximation elements and original AE wave, the results show that rock AE wave characteristics are not same in the course of transform fracture on stages, found AE wave characteristics storehouse, it is a matter of great significance for utilizing monitoring and prediction regularity and development trend in the course of fracture transform. The error between the original signal and the signal of wave coefficient of the approximation elements reconstructed is minor to, wavelet analysis makes accuracy and reliability of rock AE wave characteristics monitoring and prediction improved, States that wavelet analysis is a great efficiency method.

Dual-tree complex wavelet coefficient magnitude modelling using the bivariate Cauchy–Rayleigh distribution for image denoising

Wavelet shrinkage is a standard technique for denoising natural images. Originally proposed for univariate shrinkage within the Discrete Wavelet Transform (DWT) domain it has been made more effective through the use of (approximately) translationally invariant wavelet decompositions such as the Dual-Tree Complex Wavelet Transform (DT-CWT) and bivariate shrinkage. Techniques using the DT-CWT benefit from both (approximate) translational invariance and improved directionality. However, these techniques have used the real and imaginary components of the complex valued subband coefficients separately. The proposed work instead uses coefficient magnitudes to produce a novel bivariate shrinkage technique based on a heavy tailed bivariate distribution (of magnitudes) to provide a quantitative improvement in image denoising.The results were compared to state of the art non-local means denoising technique BM3D. The PSNR results for small amounts of noise were comparable and within a small range for larger amounts of noise. However, when using the perceptually based structural similarity metric (SSIM) our developed technique offers improved results across the range of noise inputs when compared to BM3D in many cases. Perceptually, the developed technique is able to retain a greater quantity of the high frequency elements of the input image compared to BM3D.

Optical micromachined ultrasound transducers (OMUT)-a new approach for high-frequency transducers

The sensitivity and reliability of piezoelectric ultrasound transducers severely degrade in applications requiring high frequency and small element size. Alternative technologies such as capacitive micromachined ultrasound transducers (CMUT) and optical sensing and generation of ultrasound have been proposed and studied for several decades. In this paper, we present a new type of device based on optical micromachined ultrasound transducer (OMUT) technology. OMUTs rely on microfabrication techniques to construct micrometerscale air cavities capped by an elastic membrane. A modified photoresist bonding process has been developed to facilitate the fabrication of these devices. We will describe the design, fabrication, and testing of prototype OMUT devices which implement a receive-only function. Future design modifications are proposed for incorporating complete transmit¿receive functionality in a single element.

Territorial reactions of male Yellowhammers (Emberiza citrinella) toward a specific song structure

Male songbirds assess their rivals by listening to their songs and, in some species, are especially sensitive to certain parts of the song. Yellowhammers (Emberiza citrinella) sing songs with different structures consisting of an initial phrase of stereotyped and repeated notes in a trill, and a terminal phrase, present or not, which consists of low or high frequency whistles that we called elements. We analyzed 1,055 songs from 25 different males and found that four different structures could be distinguished in a French Yellowhammer population. We found that the frequency ranges of the elements were more constant across individuals than the ranges of the notes, and among them, the low frequency element was nearly twice as conserved as the high frequency element. Then, in the wild, we tested the territorial responses of males to the four different structures and found that the full song structure, which is composed of the initial phrase followed by a high frequency element and a low frequency element, induced stronger territory defence responses from the males than any of the other structures. As only the structure containing the initial phrase and the low frequency element also induced a strong response, we propose that the main element responsible for the enhanced reaction of the males is the low frequency element, which is consistent with the fact that it is more conserved than the other constituents.