Ratio Of Wave Amplitude Research Articles

Simultaneous analysis of swirl spray dynamics using a telecentric shadowgraphy system

Abstract Pressure swirl injectors generate conical hollow sprays with a liquid film adjacent to the exit nozzle. This paper describes macroscopic and microscopic parameters of sprays and disturbances of the liquid films formed by dual pressure swirl injectors, utilizing a telecentric shadowgraphy optical system. High-speed images with kHz frequencies were used for the simultaneous measurement of spray cone angles, breakup lengths, mean droplet velocities and wave amplitude ratios. Two injectors were tested with inner nozzles having Abramovich geometric constants Kint = 2 and 2.125 and external nozzles with geometric constants Kext = 2.9 and 1.9792, respectively. Water was used as test fluid and the injection pressures were varied from 0.05 to 0.5 MPa. Simultaneous data from the same set of images allowed the calculation of the maximum surface wave growth rate. The results indicated that the maximum surface wave growth rate varies approximately linearly with the injection pressure. Measured maximum amplitude ratios of the conical liquid film disturbances varied in the range 2.32 < ln⁡〖((η_bu)⁄(η_0))〗 < 4.61, relatively close to recent experimental data on conical liquid films, but significantly lower than the calculated values for planar liquid films. The maximum amplitude ratio is a crucial parameter to determine breakup lengths. A new semi-empirical equation is proposed to describe the disturbance ratios of conical liquid films of pressure swirl injectors. 

Hearing in Two Closely Related Peromyscus Species (Peromyscus maniculatus and P. leucopus).

The genus Peromyscus has been extensively used as a model for ecological, behavioral, and evolutionary investigations. We used auditory brainstem responses (ABRs), craniofacial morphology, and pinna measurements to compare characteristics that impact hearing in two wild-caught species, P. leucopus P. maniculatus. We observed significant statistical differences in craniofacial and pinna attributes between species with P. leucopus overall exhibiting larger features than P. maniculatus. ABR recordings indicated that both species showed similar best frequency thresholds between 8-24 kHz. We found significant effects of intensity on amplitude ratio of wave I and IV for P. maniculatus, but not P. leucopus and effects of wave number on slope of the latency-intensity function with higher wave IV and shorter wave I slope of latency intensity function in P. leucopus. Finally, the data showed significant differences in latency shift of the DN1 component of the BIC in relation to ITD between species, while no significant differences were observed across relative DN1 amplitude. This study supports the used of P. leucopus and P. maniculatus as future model species for auditory research.

Numerical study of using dual sources constructed via deconvolution to suppress the collar waves in acoustic logging while drilling

In the design of acoustic logging while drilling (LWD) instruments, acoustic isolation is crucial to prevent the loss of formation signals due to collar waves. A conventional approach involves carving periodic grooves on the drill collar to isolate collar waves, but this can compromise the mechanical integrity of the collar. In this paper, we introduce a novel method using dual sources to suppress collar waves generated by a monopole source. This method added a new near-source to the original acoustic LWD instrument, and its input signal is constructed via deconvolution. The effectiveness of this method is first verified using the finite-difference time domain (FDTD) in an infinite fluid medium. The amplitude ratio of the collar wave’s average frequency spectrum (0–20 kHz), excited by the deconvolution-type dual sources (DCDS), compared to a single far-source, is only 1.57%, effectively suppressing most of the collar waves. Since formations do not significantly affect the propagation characteristics of collar waves, this method remains effective in various formations, as corroborated by simulation results. Additionally, we applied the wave interference-based slowness-time-coherence (STC) method to successfully extract the formation P-wave velocity even when collar wave velocity and formation P-wave velocity are similar. This method provides an effective approach to suppress monopole collar waves without compromising the collar’s integrity and mechanical strength.

Effectiveness of auditory measures in the diagnosis of cochlear synaptopathy and noise-induced hidden hearing loss: a case–control study

BackgroundCochlear synaptopathy is a disorder where auditory perceptual impairments, such as speech perception in noise and tinnitus, may not be accurately reflected by audiometric thresholds, even if the audiogram appears normal. It is proposed that the connections between hair cells and the auditory nerve are more susceptible to sound and aging damage than the cochlea’s hair cells. Cochlear synaptopathy can be present in ears with normal audiograms and undamaged hair cells, leading to hidden hearing loss. This study aims to construct electrophysiological and behavioral auditory parameters associated with persons exposed to loudness and having normal audiograms and auditory complaints to identify hidden hearing loss.ResultsA case–control study was done with forty participants with a documented history of exposure to loud sounds and various auditory complaints, compared to a control group of forty persons who had all been confirmed to have normal audiograms. The chosen behavioral core tests comprised the speech intelligibility in noise test (SPIN), gaps detection in noise (GIN test), and pitch pattern sequence test (PPS). The electrophysiological measures utilized in the study were the auditory brainstem response test (ABR) and electrocochleography (ECochG). The SPIN, PPS, and GIN test results demonstrated statistically significant disparities between the control and case groups. The amplitude ratio of wave I to wave V in ABR and the ratio of EcochG AP to SP demonstrated a statistically significant variance between the two groups. The SPIN test exhibited the highest AUC, signifying its superior diagnostic capability in identifying hidden hearing loss.ConclusionThe present study has shown that the SPIN, as a behavioral test, and the EcochG AP amplitude measure, as an electrophysiological test, provide the greatest auditory diagnostic capability for identifying cochlear synaptopathy. Wave I amplitude in the auditory brainstem response (ABR) and the SP/AP ratio in electrocochleography (EcochG) are promising non-behavioral measures of cochlear synaptopathy or hidden hearing loss.

Heat transfer and fluid flow analysis of a solar air heater using conical jet impingement with sine-wave corrugation on absorber plate

In the pursuit of renewable energy solutions, solar air heaters emerge as a promising technology to efficiently harness solar thermal energy for diverse applications such as space heating, agricultural drying and industrial process heating. However, the system’s efficiency is often limited by the low heat transfer capability of air and the formation of laminar sub-layer over the absorber plate. This study addresses the issue by investigating the innovative use of conical jet impingement combined with sine wave corrugations on the absorber plate to enhance heat transfer in solar air heaters. The design parameters include wave amplitude ratio (0.079–0.314), throat jet diameter ratio (0.063–0.141), base jet diameter ratio (0.126–0.251), and Reynolds number (3200–19200) as the operational parameter. The computational fluid dynamics simulations are employed to solve the Reynolds-Averaged Navier-Stokes equations coupled with RNG k-ɛ turbulence model to assess the heat transfer and frictional characteristics, followed by experimental validation. The findings demonstrate a significant improvement in the system’s heat transfer rate with the Nusselt number increase by a factor of 6.71 times compared to a smooth solar air heater, while the friction factor increase by 13.87 times. Furthermore, the highest thermo-hydraulic performance parameter is found to be 2.79 corresponding to Reynolds number of 3200, wave amplitude ratio of 0.079, throat and base jet diameter ratios of 0.126 and 0.220, respectively. The proposed geometry will be helpful for academic researchers and can be adopted by the industries for various applications.

A novel GWAS locus influences microvascular response to mental stress and predicts adverse cardiovascular events.

Excessive peripheral microvascular constriction during acute psychologicalstress reflects similar changes in coronary blood flow and is a predictor of adverse cardiovascular outcomes. Among individuals with coronary artery disease (CAD), we sought to determine if genetic factors contribute to the degree of microvascular constriction during mental stress. A total of 580 stable CAD individuals from two prospective cohort studies underwent mental stress testing. Digital pulse wave amplitude was continuously measured and the stress/rest (sPAT) ratio of pulse wave amplitude was calculated. Race stratified genome-wide association studies (GWAS) of sPAT-ratio were conducted using linear regression of additive genetic models. A trans-ethnic meta-analysis integrated the four sets of GWAS results. Participants were followed for the outcome of recurrent cardiovascular events (myocardial infarction, heart failure, revascularization, and CV death) for a median of 5years. We used Wei-Lin-Weissfeld (WLW) model to assess the association between sPAT-ratio with recurrent events. Mean age was 63 ± 9. We identified three SNPs in linkage disequilibrium, closely related to chr7:111,666,943T > C (rs6466396) that were associated with sPAT-ratio (p = 6.68E-09). Participants homozygous for the T allele had 80% higher risk of incident adverse events (HR 1.8, 95% CI, 1.4-2.2). Also, participants with a lower sPAT-ratio (< median) had a higher adverse event rate, hazard ratio (HR) = 1.3, [95%confidence interval (CI), 1.1-1.6]. However, adjustment for the genotypes did not substantially alter the impact of sPAT ratio on adverse outcome rate.In conclusion,we have identified a genetic basis for stress-induced vasomotion. The 3 linked variants modulate vasoconstriction during mental stress may have a prognostic importance.

Effects of EEG-Neurofeedback in children with Down syndrome

Background. Down syndrome (DS) is a genetic disorder characterized by varying degrees of mental retardation and neurological complications. Children with DS often experience difficulties with attention, concentration, learning, memory, speech, language, behavior, and physical balance. Methods. This study included 11 children with DS and 10 children with ADHD, aged 6 to 10 years who received treatment at the private clinic “Neyromed Servis” in Tashkent, Uzbekistan. Cognitive functions were analyzed by using Electroencephalography-neurofeedback (EEG-NFB) and the Forbrain headsets. The Wechsler Preschool and Primary Scale of Intelligence and Schulte table were used to assess the effectiveness of non-drug treatment. Results. The utilization of Forbrain headsets enhanced children’s attentiveness as listeners and improved the quality of their voice and speaking. Positive changes in EEG parameters were also registered: theta wave amplitude and theta-tobeta ratio in the frontal lobes decreased significantly. Conclusion. EEG-NFB treatment significantly improved cognitive function, particularly attention, without any side effects in observed children. Moreover, impulsivity as well as hyperactivity decreased gradually. Additionally, after using of the Forbrain method, vocabulary in children improved by 20-40% across all groups.

The diagnostic value of T-wave to R–wave amplitude ratio on electrocardiogram in the diagnosis of hyperkalemia

Objective: The aim of this study is determining the diagnostic value of the T-wave to R–wave amplitude ratio (T/R ratio) in the electrocardiogram (ECG) at the time of admission in terms of the diagnosis of hyperkalemia in patients who are at risk for hyperkalemia who apply to the emergency department (ED). Methods: This cross-sectional study was conducted with patients over 18 years of age who presented to the ED and have an estimated glomerular filtration rate (eGFR) below 60ml/min/1.73m2. The patients were divided into 2 groups according to the potassium value; hyperkalemia and normokalaemia groups. T/R ratios were measured on the ECG. All measurements were made in these precordial leads; V2, V3, and VT highest (is defined as precordial lead where the T wave is measured the highest). Results: A total of 345 patients with low eGFR were included. Hyperkalemia was detected in 115 (33.3%) of these patients, while 230 patients (66.6%) were in the normokalaemia group. T wave amplitude and T/R ratio were found to be statistically significantly increased in the hyperkalemia group in all leads (V2, V3, and VT highest). Area under the curve (AUC) values are 0.778 for T/R ratio and 0.717 for T wave amplitude. Conclusion: The presence of increased T/R ratio in the ECG of patients with known low eGFR may be more helpful for the diagnosis of hyperkalemia than the classical hyperkalemia ECG findings.

Multipoint leak localization for pipelines via acoustic wave amplitude ratio

Pipeline leak localization is significant for maintaining the regular operation of pipelines. This paper proposes a multipoint leak localization method for pipelines via the acoustic wave amplitude ratio, which addresses the issue of the traditional time delay estimation method (TDE) not being able to locate multiple leaks simultaneously. Firstly, a multipoint leak localization method for pipelines is established without time delay estimation and acoustic velocity. This method merely needs to determine the amplitude of the leakage acoustic wave propagating to both ends of the pipeline to achieve leakage localization. Secondly, the improved empirical wavelet transform (IEWT) method denoises the leakage acoustic wave, which can obtain an accurate acoustic amplitude to reduce the localization error. Finally, the trouble that the mutation factor and crossover probability cannot be adaptively selected in the differential evolution (DE) algorithm is improved, and the improved differential evolution (IDE) algorithm is used to solve the objective function to obtain the position of each leakage point. Field experiments show that the multipoint leak localization method proposed in this paper has perfect accuracy, and the minimum localization error is 11 m.

Evaluation of free convection cooling and entropy efficiency in a porous W-shaped cavity using RSM and CFD approaches

The cooling and entropy efficiencies of natural convection inside cavities within fully saturated metal foam play a vital role in thermal engineering applications systems. The current study employed response surface methodology (RSM) coupled with ANSYS FLUENT-CFD for a two-dimensional W-shaped cavity, which has not been examined previously. Several effective physical factors were considered, including the aspect ratio (W = h/H = 0, 0.2, 0.4, 0.6 and 0.8) and the applied temperature variation (ΔT = Th − Tc = 10, 20, 30 and 40 K). Additionally, the thermal performance (NumW/NumO and QW/QO ) and entropy generation (EGW/EGO ) improved under the optimum design of pore per inch (10 ≤ PPI ≤ 30), the number of wave amplitude (1 ≤ n ≤ 3) and aspect ratio (0.2 ≤ W ≤ 0.8) utilizing both RSM and CFD. The results showed that the optimal design of natural convection within a fully saturated metal foam W-shaped cavity at PPI = 10, n = 3 and W = 0.8 resulted in enhancements of approximately 2.875 times for both NumW/NumO and QW/QO while maintaining reasonable EGW/EGO at 1.193 times. Moreover, the novelty aspect of this research lies in the successful achievement of multi-objectives improving NumW/NumO , QW/QO and EGW/EGO by applying the RSM approach in combination with ANSYS FLUENT-CFD. Thus, the optimal working procedure of RSM and CFD is aligned with the desired goals, as the cooling and entropy efficiencies of the porous W-shaped cavity are considered acceptable and satisfactory.

Effect of Sympathetic Blockade on Spontaneous Discharge and the H-Reflex at Myofascial Trigger Points in Rats.

Myofascial trigger points (MTrPs) are the main cause of myofascial pain syndrome (MPS), and patients with MPS also have symptoms of sympathetic abnormalities. Consequently, this study aimed to investigate the potential relationship between MTrPs and sympathetic nerves. Twenty-four seven-week-old male rats were randomly divided into four groups (six rats every group). Groups I and II were kept in normal condition (n=12), and groups III and IV underwent MTrPs modelling (n=12). After successful MTrPs modelling, differences in sympathetic outcomes between the MTrPs groups (III and IV) and non-MTrPs groups (I and II) were observed. Sympathetic blockade was then applied to groups III and I (n=12). Data were collected on peak inversion spontaneous potentials (PISPs) and the H-reflex-evoked electromyography during spontaneous discharge at the MTrPs before and after sympathetic blockade. Systolic blood pressure, diastolic blood pressure, mean arterial pressure, and heart rate were significantly higher in the MTrPs group than in the non-MTrPs group (P<0.05). Compared with group I, group III had the PISPs potential lower wave amplitude, shorter duration and amplitude-to-duration ratio, and lower H latency and latency difference H-M (P<0.05). Compared with group IV, group III had the PISPs potential lower wave amplitude, duration, amplitude-to-duration ratio, M-wave latency, H maximum wave amplitude, and maximal wave amplitude ratio H/M (P<0.05). The changes before and after sympathetic blockade in the MTrPs group were significant, and the amplitude, duration, and amplitude-to-duration ratio of the PISPs potentials were lower after the blockade (P<0.05). MTrPs and sympathetic nerves interact with each other forming a specific relationship. MTrPs sensitize sympathetic nerves, and sympathetic nerve abnormalities affect local muscle myoelectric hyperactivity, leading to MTrPs. This finding is instructive for the clinical management of sympathetic disorders.

Investigation on the dynamic characteristics of anchor rods considering size effect and pull-out loads based on IIR-FDM

When the surrounding rock of tunnel anchor bars has boundaries, the signals obtained from non-destructive testing (NDT) of anchor rods will be simultaneously affected by size effects and pull-out loads, leading to potential misinterpretation of the test results. In order to accurately assess the anchorage quality of anchor rods under this interference, NDT and numerical simulations of anchor rods subjected to different anchorage quality were conducted under the influence of size effects and pull-out loads. A signal filtering method, which combines the infinite impulse response-finite difference method, was proposed for identify the impact of size effects. The study analyzed the variations in wave velocity and fundamental frequency of anchor rods with anchorage defects and intact anchor rods under the influence of size effects and pull-out loads. The results indicate that the IIR-FDM method, in comparison to the traditional wavelet method, provides better agreement between the calculated wave velocities and existing findings. With the increase of size effect, the wave velocity and amplitude ratio of the anchor rods decrease, and the fundamental frequency increases first and then decreases. As the working load on the anchor rods increases, the wave velocity initially decreases, then rises, while the fundamental frequency initially increases and then experiences a slight decrease. The presence of anchorage defect results in an increase in the wave velocity and amplitude ratio of the anchor rods, while causing a decrease in the fundamental frequency. This effect of defects on wave velocity and fundamental frequency is more pronounced at lower loads. The wave velocity after IIR-FDM processing has a small error with the simulated wave velocity, indicating the reliability of the processing method.

Catalytic effects on peristaltic flow of Jeffrey fluid through a flexible porous duct under oblique magnetic field: Application in biomimetic pumps for hazardous materials

Homogenous and heterogeneous reactions play an essential role in polymer production, combustion, ceramic production, catalysis, distillation, and biochemical procedures. As a result of this advancement, a mathematical model is developed to examine the role of catalytic chemical reaction effects on the magneto-hydrodynamic peristaltic transport in a flexible divergent duct containing a non-deformable porous medium as a model for complex hazardous waste bio-inspired pumping mechanisms. The Jeffrey model is utilized to simulate strong non-Newtonian characteristics. Additional multi-physical features included in the model are heat generation, thermal radiation, Hall current, and complaint wall properties along with an inclined (oblique) magnetic field. The long wavelength and low Reynolds number approximations are deployed to transform the primitive conservation equations from a moving boundary problem to a fixed frame. Appropriate transformations are then utilized to render the model dimensionless. The exact solutions are obtained for stream function and velocity. Further, the R-K-Fehlberg integration scheme is applied to solve the energy and concentration equations. Velocity, temperature, concentration, skin friction, and Nusselt number profiles are visualized graphically. Streamline patterns are also included to capture bolus dynamics. Validation with previous simpler studies has been included. A detailed appraisal of key control parameters on transport characteristics is conducted. It is found that velocity is suppressed with elevation in the damping force parameter while it is enhanced with an increment in regime permeability i. e. Darcy number. Both homogeneous and heterogeneous reactions are observed to exert a significant impact on the species concentration. The volume of the trapped fluid bolus size is shown to be an increasing function of the peristaltic wave amplitude ratio. The present work generalizes existing studies to consider catalytic effects on dissipative peristaltic pumping of the Jeffrey fluid with heat generation and radiative flux, aspects which have been neglected in a single model previously. The simulations are relevant to better characterize the complex transport phenomena in nuclear reactor waste transport via biologically inspired pumping designs.

Numerical study on aerodynamic drag and noise of high-speed pantograph by introducing spanwise waviness

It is noteworthy to explore potential measures for further reducing the aerodynamic drag and noise of high-speed pantographs. This paper proposes a method of introducing spanwise waviness into the upper and lower arms. The improved delayed detached eddy simulation (IDDES) method and the Ffowcs Williams and Hawkings (FW-H) equation are used for flow field simulation and sound propagation calculation, respectively. The effects of wavelength, wave amplitude and inclination on the aerodynamic force and radiated noise of the wave cylinder were firstly investigated, and then the aerodynamic characteristics of the pantograph with and without spanwise waviness configurations were compared. Results show that the appropriate spanwise waviness on the cylinder can diffuse the negative pressure core area in the wake, reduce the negative pressure amplitude, suppress the vortex shedding and weaken the fluctuation amplitude of the aerodynamic force, resulting in the reduction of aerodynamic drag and noise. For the high-speed pantograph by introducing spanwise waviness, when the ratio of wavelength and wave amplitude to cylinder diameter is 1.2 and 1/8 respectively, the aerodynamic drag and noise of the pantograph by introducing spanwise waviness are reduced by 1.58% and 1.16 dBA, respectively.

Hydro-elastic interaction of polymer materials with regular waves

The use of flexible materials has the potential to offer a step-change reduction in the cost of wave energy devices by enabling them to absorb more extreme wave loads through their structural responses. Flexible wave energy converters are often manufactured from polymer, fabric, or reinforced polymer components. The elastic modulus, fatigue performance, seawater ageing, and manufacturing process determine the effectiveness of flexible components at replacing their rigid counterparts. During design, it is necessary to assess the hydrodynamic response of the WEC structure to different wave conditions. This work investigates the hydro-elastic response of a submerged polymer membrane, held in a horizontal frame, exposed to regular wave loading. Fast-Fourier Transform analysis enabled assessment of the non-linear response of the membrane exposed to the different wave conditions. The ratio of harmonic to measured wave amplitude ratio gives insight into the excitation mode of the membrane as a function of frequency. It is found that the peak response of the membrane tends to coincide with the fundamental frequency of regular waves. By varying the ratio of membrane length to wavelength an understanding is provided of the hydro-elastic response of the polymer membrane which should be useful in validating software used in the design of flexible WECs.

Investigation of Fluid Flow and Heat Transfer Characteristics in Wavy Mini-Channel Heat Sink With Interconnectors

Abstract In this paper, a novel sinusoidal wavy mini-channel heat sink (MCHS) with interconnectors (IC w-MCHS) has been introduced, and the effectiveness of the proposed heat sink over conventional mini-channel heat sink (s-MCHS) has been numerically investigated. Different parameters, i.e., wavelengths, wave amplitudes, and phase shifts of the proposed sinusoidal wavy MCHS, were varied to study its effect on thermal and hydraulic performance. This study used three different wavelengths, three different amplitudes, and two different phase shifts, and Reynolds number (Re) varied from 300 to 800. The Nusselt number (Nu) of IC w-MCHS increased as the wave amplitude ratio (α) and Re increased, whereas it increased with the decrement of the wavelength ratio (β). Nu of the IC w-MCHS was also found to depend on phase shift (θp); for θp = π, the chaotic advection and increment of flow reversal were observed in the IC w-MCHS compared to θp = 0, resulting in higher Nu and higher pressure drop penalty. Nu of the IC w-MCHS was found to be 115% higher compared to s-MCHS at Re 550, θp = π, and α = 0.3, whereas it was found 77% higher for θp = 0. The maximum temperature of the IC w-MCHS heat sink was also found to decrease compared to that of the s-MCHS due to enhanced coolant mixing. A maximum 26% decrease in the heat sink temperature was observed for the IC w-MCHS at Re 800 compared to the s-MCHS.

Investigating overtaking collisions of solitary waves in the Schamel equation

This article presents a numerical investigation of overtaking collisions between two solitary waves in the context of the Schamel equation. Our study reveals different regimes characterized by the behavior of the wave interactions. In certain regimes, the collisions maintain two well-separated crests consistently over time, while in other regimes, the number of local maxima undergoes variations following the patterns of 2→1→2→1→2 or 2→1→2. These findings demonstrate that the geometric Lax-categorization observed in the Korteweg–de Vries equation (KdV) for two-soliton collisions remains applicable to the Schamel equation. However, in contrast to the KdV, we demonstrate that an algebraic Lax-categorization based on the ratio of the initial solitary wave amplitudes is not feasible for the Schamel equation. Additionally, we show that the statistical moments for two-solitary wave collisions are qualitatively similar to the KdV equation and the phase shifts after soliton interactions are close to ones in integrable KdV and modified KdV models.

AP-452681-3 VENTRICULAR TACHYCARDIA ORIGINATING NEAR THE HIS-BUNDLE: ELECTROCARDIOGRAPHIC, CATHETER ABLATION CHARACTERISTICS AND LONG-TERM OUTCOME

Ventricular Arrhythmias (VAs) not uncommonly originate from the Para Hisian (PH) region. The clinical and electrophysiological (EP) characteristics of these VAs are important to recognize given risk of injury to the conduction system. Define the clinical and EP characteristics of these VAs and long-term outcome of catheter ablation. 43 patients (Pts.) had VAs activation mapped to the PH region. The electrocardiographic and EP characteristics of these PH VAs were compared in 50 patients with VAs originating from right ventricular outflow tract (RVOT). Mean QRS width was narrower in PH VAs (P=0.02) and the R wave amplitude was lower in the inferior leads (P = 0.01) as compared to RVOT VAs. PH VAs had an R wave amplitude greater in lead I (P= 0.001) and lead aVL (P= 0.02) than RVOT VAs. For PH VAs earliest in RV, the R wave amplitude ratio in leads II/III was greater than those in LV (P= 0.02). All left sided PH VAs (12pts) had early transition (≤Lead V2) and were infra-hisian in location. 27/31 Right sided VAs had later transition (≥ Lead V3), 22 (70%) were infra-hisian and 9 (30%) were supra-hisian in location. Inferior Lead discordance was seen in 75% of all pts and was similar in left and right sided VAs. Radiofrequency ablation (RFA) was used upfront in 39 pts. Cryo-ablation used upfront in 2 pts and after RFA in 1 pt. In 30 pts (70%) VAs were eliminated; 9 (21%) had significant suppression (≤5% total residual burden) and 3 (9%) had acute recurrence (<48 hours) and 1 pt. ablation was not attempted given immediate proximity to HB. During follow up of 46±8 months, EF normalized in 37/43 (85%). 2 Pts. developed transient heart block with no treatment needed and 1 with pre-existing pacemaker (PM) had complete heart block. 2 required PM implantations at 39 ± 2 months post ablation due to conduction system disease unrelated to ablation. VAs originating near the His-bundle have distinctive ECG characteristics which aid in recognition and mapping. Catheter ablation can generally be performed safely and effectively.

Wave propagation analysis in laminated composite periodic frame structures using spectral finite element method

In this article, wave propagation in a one-dimensional (1-D) composite periodic frame structure is analyzed using spectral finite elements (SFE) method together with Bloch’s theorem. Each element in the periodic frame structure is modeled as a first-order shear deformation theory (FSDT) beam element and wave equations for the beam elements are derived using FSDT considering axial, flexural, and shear deformations. Next, these equations are solved using the frequency domain SFE method to obtain an elemental dynamic stiffness matrix which on assembly gives the dynamic stiffness matrix for the unit cell of the periodic structure. A polynomial eigenvalue problem is formulated thereafter using Bloch’s theorem to evaluate the dispersion coefficients and wave amplitude ratios. Finally, the entire periodic frame is modeled as homogenized two-noded elements capturing the wave response of the PS with a drastic reduction in computational cost. The results obtained using the present method are validated with finite element simulation using ANSYS mechanical Ansys Parametric Design Language (APDL). The frequency band gaps observed in the frequency domain responses are investigated and corroborated with those predicted by the dispersion relations. This is followed by a detailed parametric study on the influence of different parameters on the band gap characteristics. The present method provides a scheme of wave propagation analysis of composite periodic frames with substantial computational efficiency.

Theoretical model on the slug/churn transition based on the generation and evolution of the huge waves

Previous experimental studies have proved that the flooding of the falling film surrounding the Taylor bubble is attributed to the transition from the slug flow to the churn flow, which is related to the generation and evolution of huge waves. In the present study, theoretical models on the basis of the Kelvin–Helmholtz instability of the falling film around the Taylor bubble and kinematic analysis of the interfacial wave traveling on the falling film are, respectively, established to reveal the mechanism of the slug/churn transition. The formation of the liquid bridge or pseudo-liquid bridge is taken as the judgment basis to determine the transition. A term named “most dangerous wave” is introduced in the present study, and its criteria is related to the ratio of wave amplitude to pipe diameter. Verified by the data and models in the literature, the proposed model is demonstrated to have satisfactory predicting accuracy. In addition, parameters, including pipe diameter and system pressure, are analyzed in detail to discuss their effect on the slug/churn transition. The results indicate that the slug/churn boundaries move downward as the system pressure increases but upward with the increasing pipe diameter. We believe that the findings in this paper benefit a better understanding of the relation between the huge waves and slug/churn transition.