wave front analysis techniques

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Efficacy of analysis techniques in assessing broken wave loading on a cylinder upon a shoal

Efficacy of analysis techniques in assessing broken wave loading on a cylinder upon a shoal

Abstract: Estimation of impulsive wave loading and runup on a cylinder upon a shoal, typified by an offshore lighthouse on a partially emerged rock with a steep foreshore, poses a unique challenge to marine structural engineers. The foreshore geometry enables large waves to break at the base of the structure or in close proximity. The bore generated from the breaking wave has much higher velocities compared to oscillatory velocities in offshore conditions, and the highly aerated and turbulent nature of the flow makes it difficult to simulate using existing numerical models. Furthermore, most of the existing force models used to estimate impulsive forces acting on vertical cylinder are not directly applicable. Therefore, physical modelling investigations are the most feasible methods to study this phenomenon. This paper presents the data analysis techniques and the key findings of a series of small-scale wave flume tests conducted as a part of on-going research project: STORMLAMP – STructural behaviour Of Rock Mounted Lighthouses At the Mercy of imPulsive waves. This project is a collective effort of three UK universities: the University of Plymouth, the University of Exeter and University College London, which brings together expertise in both fluid and structural dynamics.
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Inverse Problems and Post Analysis Techniques for a Stenosis-Driven Acoustic Wave Propagation Model

Inverse Problems and Post Analysis Techniques for a Stenosis-Driven Acoustic Wave Propagation Model

The central obstacle to the development of the acoustic wave propagation model is an appropriate constitutive relationship to be used in the equations of motion [3]. Fung’s Quasi-Linear Viscoelastic theory provides an excellent description of the relationship be- tween stress and strain in biological materials by assuming there is a continuous spectrum, and not a finite number, of relaxation times [4]. But the computational cost of implement- ing Fung’s constitutive relationship is restrictive. Thus, we will employ internal variables to reduce computational time while preserving the accuracy of Fung’s theory, a task already accomplished in the one and two dimensional setting. We will then demonstrate that the model does indeed capture viscoelasticity and spatially dependent densities.
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Wave Damping Observed in Upwardly Propagating Sausage-mode Oscillations contained within a Magnetic Pore

Wave Damping Observed in Upwardly Propagating Sausage-mode Oscillations contained within a Magnetic Pore

Intensity time series for the 4170 Å continuum and G-band data sets were extracted for those pixels which lay within the con fi nes of the binary map. The time series were then detrended by a fi rst-order polynomial to remove long term variations in intensity and/or light levels, and normalized to their subsequent mean. Wavelet analysis techniques were applied to the time series to identify the presence of periodic signals. Strong oscillatory power was detected in both bandpasses, with periodicities predominantly in the range of 3 – 5 minutes, which overlap well with the typical solar p-mode spectrum ( Lites et al. 1982 ) . Next, the phase difference analysis techniques detailed by Jess et al. ( 2012b ) were employed to investigate whether the oscillations were detect- able co-spatially in the neighboring bandpasses, and whether there was an inherent phase shift. Here, a positive phase angle indicates that a wave is fi rst observed at a lower atmospheric height ( i.e., the wave is propagating upwards from the 4170 Å continuum to the G-band ) , with criteria de fi ned to ensure con fi dence in the fi nal results. First, only waves that exhibited a cross-correlation coef fi cient greater than 50% between the bandpasses were considered in an attempt to ensure the oscillatory signature corresponded to the same wave. Second, only waves which displayed a lifetime greater than 2 P in each bandpass were included, where P is the period of the oscillation in seconds, to ensure these signatures are periodic rather than lone spikes in the time series. These rigorous criteria were implemented on each extracted time series, with approximately 1700 suitable periodicities identi fi ed in the period range 210 – 412 s, with a mean value of 290 ± 31 s. The derived individual phase angles between these detected oscillations were collected into a histogram employing 1 ° bins ( as detailed in Figure 2 ) . A best- fi t Gaussian was applied, with the centroided value identifying the most commonly occurring phase angle. In the case of 4170 Å continuum – G-band, the dominant angle found was ≈ 6.12 ± 4 ◦ . 6, indicating upward
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How to Make a Mudsparkler

How to Make a Mudsparkler

Harmonic analysis assumes a harmonic forcing function and determines the steady- state response of a structure. Harmonic analysis provided responses for a frequency sweep which allowed for analysis over a frequency band, including points of maximal amplitude. The transient analysis assumed only linear elasticity (and coupled field piezoelectricity, when appropriate). Thus, the transient analysis directly solved the 3D elasticity equations of motion of a solid medium presented in Chapter 2. These equations under stress free conditions devolve into the Rayleigh-Lamb equations and will numerically solve for Lamb waves if a plate with stress free conditions is set up in the FEM formulation. A numerical solution is necessary to assess the sensor mechanics, although in practice one can use an analytical approach for the wave propagation in the plate, such as in research by Gawronski on transducer design (Gawronski et al. 2017).
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A QA pair generation system for the
incident tickets of a public ICT Shared Service Center

A QA pair generation system for the incident tickets of a public ICT Shared Service Center

Tokenization is the process to split sentences into words, of which the collection is commonly called a “bag of words”. To be able to compare all of these words, they are turned into lowercase words. Next, stop words can be removed for topic extraction, as stopwords are not contributing to this end and are consequently considered as noise. Stemming is a process in which the last characters of words are cut off using a simple algorithm removing common prefixes. This process further increases the normalization of words. Next to stemming there is also a more advanced variant called lemmatization. This process is mostly based on deep learning and brings back words to their root form. For instance: is > be, and bought > buy. Spelling correction is mostly performed using an edit-distance or Levenshtein algorithm. This algorithm computes the number of operations to change one word into another. Then noise removal is typically the process of removal of specific system or text-type related characters like timestamp or mail-signatures. Noise removal can be performed using many different techniques ranging from regular expressions to deep learning. N-gram extraction is the process of finding common sequences of n-amount of words. It is used to find topics within sentences or to find common concatenations of words. It can range from frequency-based calculations to advanced deep learning models. Finally, word embedding is the most abstract technique in this list as it is the transformation of words into digits with the purpose of preparing text for Machine Learning. The most common word embedding technique is used in more than 80% of search-related systems is TF-IDF (Term Frequency-Inverse Document Frequency). TF-IDF is a vector for a word depicting how often the word appears in a document to how often it appears in a larger set of documents. Thus the less often the term occurs in other documents, the higher its TF-IDF score.
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Dielectric Slab Mode Antenna for Integrated Millimeter wave Transceiver Front ends

Dielectric Slab Mode Antenna for Integrated Millimeter wave Transceiver Front ends

Abstract A novel type of integrated dielectric antenna is presented, which is suitable for low-loss integrated transceiver front-ends in the upper microwave or millimeter wave frequency ranges. The proposed antenna comprises a dielectric high permittivity substrate acting as grounded slab waveguide and a simple planar lens on top for beam focusing. The guided wave is gradually transformed to free space by a curved ground plane for end-fire radiation from the substrate edge. Apart from high radiation efficiency due to very low conductor losses, the use of a standard substrate material also simplifies manufacturing and allows accommodating MMICs or bias circuitry at minimum cost. Simulation and measurement results are presented for a scaled prototype in X-band. Simulation studies were also conducted at millimeter-wave frequencies, where the low-loss advantage is even more evident. Having dimensions of 10 mm × 18 mm, an example design provides a gain of 15 dBi at 60 GHz and a radiation efficiency of more than 80 % if a Duroid ® 6010LM
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Developing methodologies for large scale wave and tidal stream marine renewable energy extraction and its environmental impact : an overview of the TeraWatt project

Developing methodologies for large scale wave and tidal stream marine renewable energy extraction and its environmental impact : an overview of the TeraWatt project

The objectives of TeraWatt are fourfold: Firstly, to minimise de- lays in array licensing by providing answers to 3 speci fi c questions identi fi ed by MSS as critical for the regulatory authorities, respon- sible for the licensing of wave and tidal developments; and, sec- ondly, to collect the methodologies used to answer these into a “ methods toolbox ” that can be more widely utilised for EIA, and in which the MRE developer community has con fi dence. Much of the toolbox description has been reported in a collection of “ Posi- tion Papers ” that are listed below in association with their respec- tive workstreams. The peer review papers included in this special issue contribute to the description of such methodology and are also listed below. For other project dissemination outputs, see Table 1.
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Optical Eigenmodes; exploiting the quadratic nature of the energy flux and of scattering interactions

Optical Eigenmodes; exploiting the quadratic nature of the energy flux and of scattering interactions

On a final note, we remark that squeezing light below its diffraction limit may be associ- ated with the effect of super-oscillations [15]. This refers specifically to the ability to have a local k-vector (gradient of the phase) larger than the spectral bandwidth of the original field. To visualize this effect, in the case of OEi spot size optimized beams, we have calculated the spectral density of the radial wave-vector for the smallest planar spot [16]. As shown in Fig. 3, this spectral density clearly identifies a spectral bandwidth (white background in Fig. 3). Re- gions of the beam which exhibit locally larger wave-vectors than the ones supported by this spectral band width correspond to super-oscillating regions. The local wave vector is defined as ∂ r arg(u(r)) where arg(u) defines the phase of the analytical signal u. In this particular case,
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Multiple satellite observations of oceanic planetary waves: techniques and findings

Multiple satellite observations of oceanic planetary waves: techniques and findings

In recent years, satellites have allowed an unprecedented study of planetary waves (also known as Rossby waves) in the oceans. These waves are a key dy- namical phenomenon owing their existence to the conservation of potential vortic- ity (akin to angular momentum) and in turn to the rotation and shape of our planet, and have significant effects on the large scale ocean circulation and on the trans- port of climatic information across the main ocean basins (see for instance Gill, 1982). Planetary waves are essentially internal waves, that is disturbances in the vertical density field, also present in the atmosphere. In the oceans, they travel from east to west at speeds of the order of a few cm/s (depending on latitude: they go faster closer to the equator) and can take months or years to cross the main oce- anic basins. The considerable difference in the horizontal and vertical scales of the waves is what makes them so hard to pin down with in situ observations: while the typical horizontal scale (corresponding to wavelength if the phenomenon were pe- riodic) is hundreds or thousands of km, the vertical amplitude of the oscillation is a few tens of meters at the depth of the thermocline and the signature of the wave in the sea surface elevation is only a few centimetres. Thus it is not surprising that planetary waves, easily observed in the atmosphere since their discovery by Carl- Gustav Rossby in the 1930s, have eluded observation in the oceans until recently.
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Boundary layer flow beneath an internal solitary wave of elevation

Boundary layer flow beneath an internal solitary wave of elevation

The flow reversal seen in the bottom boundary in the decelerating part of the wave-induced flow was shown to be similar in nature to that found under surface solitary waves. 21–23 Liu et al. 22 suggest that the reversal is a result of a phase lag between the irrotational and rotational velocity components. Carr and Davies 25 and Carr et al. 26 presented experimental evidence of a similar flow reversal at the lower boundary under an ISW of depression in the decelerating part of the wave-induced flow aft of the crest but conjectured that the flow reversal was a result of boundary layer separa- tion in the adverse pressure gradient region. In both in- stances, however, a reverse flow is seen in the decelerating part of the flow 共aft of the wave crest/trough兲. Hence, it may be that the reverse flow under an ISW of depression is also the result of a phase lag between the irrotational and rota- tional velocity components and is not the result of the ad- verse pressure gradient region as previously proposed. 16,25,26 On the other hand, the wave-induced flow under ISWs of differing polarity have significant differences and a direct comparison of the two should be made with caution. For example in the elevation case, there is strong shear 共i兲 at the crest of the wave, where the wave-induced velocity changes sign, and 共ii兲 at the lower boundary where there is a no-slip requirement. The velocity gradient is oppositely signed at the crest and the lower boundary, respectively, for example see Moum et al. 6 Fig. 9. Hence, oppositely signed vorticity is injected into the wave core at the crest and at the lower boundary, respectively. This is in contrast to the depression case where the wave core is bounded above by a free surface and below by the wave trough. The free surface does not generate the same kind of high stresses that the lower solid boundary does in the elevation case and, in consequence, input of vorticity into the wave core is significantly different in the two cases. Moreover, the wave-induced shear stress generated at the bottom boundary beneath an ISW of eleva- tion is expected to be higher than in the depression counter- part as the pycnocline is located nearer the bed and so the wave-induced velocity field is stronger.
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Quality Improvement in Millimeter Wave Generation Techniques

Quality Improvement in Millimeter Wave Generation Techniques

Radio over fiber system is one of the emerging techniques which combines wired and wireless transmission. Here radio frequency signal is used for wireless transmission and an optical fiber is used for wired transmission. Radio over fiber system supports different modulation schemes and millimeter wave transmission is one of the most popular approaches. The major benefits of RoF technologies are large bandwidth, reduced power consumption, low attenuation losses, multi- operator and multi-service operation.

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A Broadband T/R Front End of Millimeter Wave Holographic Imaging

A Broadband T/R Front End of Millimeter Wave Holographic Imaging

The circuit link of the broadband millimeter wave frequency synthesizer is shown in Figure 2. The front-end frequency multiplier bandwidth is determined by the base-band signal, the reasonable frequency and the pass band of the filter, which will meet the need of the transverse resolution of the imaging system. The output power determines the dynamic range of the system. Three-grade frequency-doubled structure is adopted in this fre- quency multiplier circuit link. The input signal of the frequency synthesizer from 3.875 GHz to 4.5 GHz, which passes through the frequency multiplier, becomes a broadband frequency synthesizer with frequency bandwidth of 5 GHz, from 28 GHz to 33 GHz.
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An analysis of changes to transient processes occurring in trunk pipelines as a result of introducing drag-reducing agents

An analysis of changes to transient processes occurring in trunk pipelines as a result of introducing drag-reducing agents

|x| = the distance travelled by the wave front from its initial position It should be kept in mind this relationship is obtained for laminar-flow regimes (ahead of the wave front and behind it), for which DRAs are deliberately not used (as they have zero efficiency). However, it may be of interest to assess the possibility of using Equn 1 for turbulent-flow regimes, including for liquids containing DRAs. Parameters relating to liquids with an additive and without an additive will be denoted respectively as superscript A and Ο. Wave propagation will now be examined for liquids with an additive and without an additive, given identical flow characteristics, both ahead of the hydroblow wave front, and behind it. According to Zhukovsky’s formula, the identical nature of flows in the hydroblow wave by flow rate is guaranteed under the condition ∆ P A = ∆ P P O ( A ≠ P O ) .
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Magneto thermoelastic waves in a perfectly conducting elastic half space in thermoelasticity III

Magneto thermoelastic waves in a perfectly conducting elastic half space in thermoelasticity III

Recently, Green and Naghdi [5, 6] developed a theory where the characteristics of ma- terial response for thermal phenomena are based on three types of constitutive response functions, labeled as types I, II, and III. The nature of these three types of constitutive equations is such that when the respective theories are linearized, type I is the same as the classical heat conduction equation (based on Fourier’s law), whereas the linearized version of type II theory accommodates finite thermal wave speed and involves no dissi- pation of thermal energy. Further, the type III theory involves a thermal damping term. The mixed third-order derivative term appearing in the heat transport equation destroys the wave structure. Accordingly, this equation predicts a non-wave-like heat conduction different from the usual diffusion equation predicted by the conventional parabolic heat equation. This theory admits an infinite speed of thermal propagation. This model admits coupled damped thermoelastic waves. The purpose of the present study is to consider magneto-thermoelastic waves in an elastic half-space in contact with a vacuum due to a thermal shock applied on the stress-free plane boundary in the context of the thermoe- lasticity theory III. The medium is supposed to be a perfect electrical conductor and both media are permeated by a primary uniform magnetic field parallel to the plane boundary. Short-time solutions for displacement, temperature, stress, perturbed fields in the half- space and that in the vacuum are derived. The solutions for displacement, temperature, stress, and perturbed field in the solid consist of an elastic wave front with attenuation and a diffusive part due to the damping term present in the heat transport equation. The perturbed magnetic field in vacuum represents a wave front without any attenuation trav- eling with Alfv’en acoustic wave speed. Displacement and temperature in the half-space are found to be continuous at the elastic wave front, while the stress and the perturbed magnetic field in the solid both experience finite discontinuity at the same location. The finite discontinuities are not constants but decay exponentially with distance from the boundary.
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Effects of front and back squat techniques on
patellofemoral joint kinetics in males

Effects of front and back squat techniques on patellofemoral joint kinetics in males

Unfortunately, due to the nature of the barbell squat, high levels of flexion at the knee joint means that the propensity for injury is high, particularly at the knee itself [7-10] . Patellofemoral pain syndrome is the most frequently encountered chronic pathology of the knee in athletic populations [11, 12] . Patellofemoral pain is linked to chronic overloading of the patellofemoral joint itself, during dynamic activities [13, 14] . Such disorders can be debilitating, and patellofemoral pain syndrome has been identified as a pre-cursor to the advancement of osteoarthritis in later life [15] . It is therefore important to better understand the forces that are produced through the patellofemoral joint when different squat techniques are employed. Although previous analyses have considered the biomechanical variations between the front and back squat lifts, there remains little clinical research concerning the two squat modalities regarding the stresses experienced by the patellofemoral joint itself.
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Volume 37: Kommunikation in Verteilten Systemen 2011

Volume 37: Kommunikation in Verteilten Systemen 2011

In our work with scientific workflows we recognized that deactivation of the old model introduces a restriction, which hampers the fulfillment of an actual requirement in scientific workflows. There are cases where it is required to keep both the old and new model active, e.g. to be able to re-execute a former configuration of an experiment. A few existing business workflow systems already provide this kind of feature [8, 9], which shows that it is also a relevant requirement in business scenarios. However, a general and implementation- independent concept for workflow evolution with more than one active model versions in combination with instance migration techniques is missing so far.
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Estimating front-wave velocity of infectious diseases: a simple, efficient method applied to bluetongue

Estimating front-wave velocity of infectious diseases: a simple, efficient method applied to bluetongue

Understanding the spatial dynamics of an infectious dis- ease is critical when attempting to predict where and how fast the disease will spread. The use of simulation model- ling for estimating the spread of infectious animal diseases has now become common [1-4]. However, most of these modelling approaches are complex, based on spatially explicit, stochastic, state-transition or network models [2,5-7] or on diffusion equations [8,9]. While such model- ling approaches require precise knowledge on the model parameters, available data on emerging animal diseases are often restricted to case reports providing only date and location. These limited data nevertheless can provide use- ful information on the direction and speed of disease diffu- sion and be used to estimate front-wave velocity of an infectious disease. We illustrate an approach using a trend-surface analysis (TSA) model combined with a
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System Simulation of RF Front End Transceiver for Frequency Modulated Continuous Wave Radar

System Simulation of RF Front End Transceiver for Frequency Modulated Continuous Wave Radar

In the system design of the RF front-end transceiver, a designer uses Friis equation and IP3 cascaded system equation for noise and nonlinearity estimate. The designer employs these equations to distribute the system specifications to the individual receiver blocks. Aleksandar et. al. [14] introduced a procedure for optimal allocation of the performance parameters to the individual RF front-end circuit blocks based on these two equations. However, there should be a simulating methodology to gain exactness of the system design as these two equations have their limitations. For the first time, to the best of our knowledge, a system level simulation methodology is proposed and thoroughly explained. The model of the target is included; the VCO phase noise has been also modeled in the simulation. Other effects, although not included, can be easily incorporated in the simulation. For example, one can model the attenuation and noise carried by the channel between the antenna and the target model.
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Determination of shear wave velocity and shear modulus estimation of peat soil using seismic geophysical method

Determination of shear wave velocity and shear modulus estimation of peat soil using seismic geophysical method

method and seismic refraction method. For accuracy in determining dynamic soil properties, many researchers preferred invasive method since it can directly measure wave in the ground without major interferences from surface activities such as traffics, vibrating machine or anything creates vibration. Soupios et al. (2005) also said that most scientists preferred to apply Crosshole and Downhole Seismic (CHS and DHS) tests, since they are highly accurate methods for determining material properties of rock and soil sites. Non-invasive method is a technique using geophone sensor and is placed on the ground surface to capture seismic wave velocity without doing any major damage to the ground surface. Recently, Multi-channel Analysis Surface Wave (MASW) is the most popular method for non-invasive method because it can obtain large volume information on soil formation. MASW method was developed to estimate shear wave velocity profile from surface wave energy and it is powerful, rapid and cost effective tool for constraining shallow wave velocity structures (Park et al., 1999)
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The idea that an ascending front of 'charnockitizing' carbonic fluids will create and push ahead a wave of 'migmatizing and granite producing' aqueous solutions is unrealis[r]

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