Field Investigation on the Effects of Base Plate Material on Experimental Surface Wave Data with MASW

2020 ◽  
Vol 25 (2) ◽  
pp. 255-274
Author(s):  
Siavash Mahvelati ◽  
Joseph Thomas Coe ◽  
Philip Asabere
Keyword(s):  
Surface Wave ◽  
Power Spectra ◽  
Base Plate ◽  
Field Investigation ◽  
Signal Frequency ◽  
Frequency Variation ◽  
Frequency Content ◽  
Promising Alternative ◽  
Masw Method ◽  
Base Plates

Source characteristics significantly affect the signals generated during seismic testing. Proper source selection plays a major role in data quality and can potentially improve investigation outcomes. This is particularly true for surface wave testing where the goal is to establish the frequency variation of phase velocity. Little research has compared the input energy caused by different base plates when impact sources are used. Consequently, data were collected using the Multichannel Analysis of Surface Waves (MASW) method with three base plate configurations (aluminum, aluminum over a rubber mat, and polyethylene) and two different sledgehammers. The variations in signal frequency content and amplitude spectra, energy, and dispersion images were systematically analyzed. There were appreciable differences in the energy introduced by different base plate configurations. Both the aluminum/rubber and the polyethylene base plates led to power spectra increases relative to the aluminum base plate. Subsequently, the aluminum/rubber and polyethylene base plates typically transferred more energy into the subsurface. This was not necessarily the case when the base plates were used on soft surficial soils. The variations in predominant frequency content were also less substantial, though the aluminum/rubber and polyethylene base plates developed slightly lower-frequency content at the expense of higher-frequency components in the dispersion curves. Despite the noticeable differences in energy transfer and frequency content, the base plate materials did not appreciable alter interpretation of the dispersion behavior at the sites given the uncertainty present in the dispersion images. This highlights that the selection of MASW base plate materials can be correspondingly driven by practical considerations such as noise, portability, and durability. Consequently, base plate materials with viscoelastic characteristics are a promising alternative to conventional metallic plates for coupling impact sources in surface wave testing, though care should be exercised when employing them at sites with soft ground conditions.

Thermally Optimum Natural Convection Cooled Longitudinal-Plate Heat Sinks With Horizontal Base Plates

2001 ◽  
Author(s):  
K. K. Sikka ◽  
C. George
Keyword(s):  
Natural Convection ◽  
Heat Sink ◽  
Base Plate ◽  
Heat Sinks ◽  
Geometrical Parameters ◽  
Plate Heat ◽  
Horizontal Orientation ◽  
Fin Spacing ◽  
Base Plates ◽  
Weakly Dependent

Abstract Longitudinal-plate fin heat sinks are optimized under natural convection conditions for the horizontal orientation of the heat sink base plate. The thermal performance of the heat sinks is numerically modeled. The fin height, thickness and spacing and heat sink width are systematically varied. The numerical results are validated by experimentation. Results show that the thermal resistance of a heat sink minimizes for a certain number of fins on the base plate. The fin spacing-to-length ratio at which the minimum occurs is weakly dependent on the fin height and thickness and heat sink width. The flow fields reveal that the minimum occurs for the heat sink geometry in which the number of fins are maximized such that the flow velocity as the air exits the fins is fully developed. A correlation of the heat transfer with the heat sink geometrical parameters is also developed.

New GaN Power-Electronics Packaging Solutions: A Thermal Analysis using Raman Thermography

2010 ◽  
Vol 2010 (1) ◽  
pp. 000446-000449
Author(s):  
M. Faqir ◽  
A. Manoi ◽  
T. Mrotzek ◽  
S. Knippscheer ◽  
M. Massiot ◽  
...  
Keyword(s):  
Base Plate ◽  
Heat Diffusion ◽  
Heat Extraction ◽  
Dramatic Improvement ◽  
High Electron ◽  
Operation Condition ◽  
Thermal Dynamics ◽  
Diamond Composite ◽  
Base Plates ◽  
Device Operation

Raman thermography measurements were performed on AlGaN/GaN multi-finger high electron mobility transistors (HEMTs) to determine their channel temperature at various power levels. The devices were mounted on both silver diamond composite and CuW base plates, in order to benchmark the thermal performance of novel diamond composite base plates compared to traditional materials. We illustrate that AlGaN/GaN HEMT devices mounted on silver diamond composite base plates show peak temperatures which are 50% lower than the peak temperatures exhibited by devices mounted on traditional CuW base plates. This is a dramatic improvement in terms of heat extraction, as basis to enabling longer device life-times and better performances. In addition, time-resolved Raman thermography measurements were carrier out to obtain thermal dynamics of devices on the silver-diamond base plate and on heat diffusion during pulsed device operation. This time-dependent information is of great importance for reliability and failure analyses, as pulsed operation of a HEMT is a typically device operation condition. Finite-element thermal simulations were performed for comparison with the experimental results, and good agreement with the experimental data was obtained.

scholarly journals A Highly Reliable, 5.8 GHz DSRC Wake-Up Receiver with an Intelligent Digital Controller for an ETC System

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 4012 ◽  
Author(s):  
Imran Ali ◽  
Muhammad Asif ◽  
Muhammad Riaz Ur Rehman ◽  
Danial Khan ◽  
Huo Yingge ◽  
...  
Keyword(s):  
High Reliability ◽  
Digital Controller ◽  
Signal Frequency ◽  
Frequency Variation ◽  
Cmos Process ◽  
Rf Transceiver ◽  
Chip Area ◽  
Current Consumption ◽  
Toll Collection ◽  
Complex Analog

In this article, a highly reliable radio frequency (RF) wake-up receiver (WuRx) is presented for electronic toll collection (ETC) applications. An intelligent digital controller (IDC) is proposed as the final stage for improving WuRx reliability and replacing complex analog blocks. With IDC, high reliability and accuracy are achieved by sensing and ensuring the successive, configurable number of wake-up signal cycles before enabling power-hungry RF transceiver. The IDC and range communication (RC) oscillator current consumption is reduced by a presented self-hibernation technique during the non-wake-up period. For accommodating wake-up signal frequency variation and enhancing WuRx accuracy, a digital hysteresis is incorporated. To avoid uncertain conditions during poor and false wake-up, a watch-dog timer for IDC self-recovery is integrated. During wake-up, the digital controller consumes 34.62 nW power and draws 38.47 nA current from a 0.9 V supply. In self-hibernation mode, its current reduces to 9.7 nA. It is fully synthesizable and needs 809 gates for its implementation in a 130 nm CMOS process with a 94 × 82 µm2 area. The WuRx measured power consumption is 2.48 µW, has −46 dBm sensitivity, and a 0.484 mm² chip area.

Acoustic Non-Reciprocal Band Structure in a Passive, Nonlinear, 1D Material

2019 ◽  
Author(s):  
Lezheng Fang ◽  
Amir Darabi ◽  
Alexander F. Vakakis ◽  
Michael J. Leamy
Keyword(s):  
Numerical Study ◽  
The Other ◽  
Signal Frequency ◽  
Strong Nonlinearity ◽  
Frequency Content ◽  
Minimal Distortion ◽  
Shape Structure ◽  
Band Pass ◽  
Path Dependent ◽  
Mechanical Devices

Abstract Acoustic non-reciprocity, referring to the phenomenon of path-dependent propagation, has diverse applications in mechanical devices. This paper presents a numerical study on a periodic triangle-shape structure that breaks reciprocity in a passive manner over a broad range of frequency and energy. The proposed structure contains strong nonlinearity and geometric asymmetry, which contributes to a direction-dependent dispersion relationship. When the signal frequency falls in the band pass in one direction, and band gap in the other, a unidirectional wave propagation results. The system achieves giant non-reciprocity with minimal distortion in the frequency content of the signal.

Comparing high-sensitivity geophones to fiber-optic DAS technologies in a hard-rock VSP survey

2020 ◽  
Author(s):  
Björn Lund ◽  
Anna Stork ◽  
Michael Roth ◽  
Ari David ◽  
Andy Clarke ◽  
...  
Keyword(s):  
Fiber Optic ◽  
Transfer Functions ◽  
Incidence Angle ◽  
High Sensitivity ◽  
Gauge Length ◽  
Signal Frequency ◽  
Nuclear Waste Repository ◽  
High Signal ◽  
Frequency Content ◽  
Velocity Signal

<p>As part of the preparations for a microseismic network on the planned nuclear waste repository in Forsmark, Sweden, we carried out a suite of measurements for site characterisation and instrument testing using geophones and DAS fiber-optic technology. Three high-sensitivity 240 V/m/s geophones were grouted into a 200 m deep borehole together with a linear, a helical and a helical engineered fiber-optical cable. Two different interrogators were used for DAS acquisition. We performed a walk-away vertical seismic profile (VSP) survey with 10 m source spacing out to 1.1 km offset and compare the responses of the four different measurement systems. The complete transfer functions of the fiber-optic systems have not yet been determined, and depend on factors such as incidence angle, signal frequency content and the fiber gauge length. Preliminary results show that all systems record signals with high signal-to-noise ratio and that which system has highest performance depends on source-receiver distance, signal frequency content and wave incidence angle. Due to incomplete knowledge of the fiber transfer functions we cannot match the DAS velocity signal with the geophone signal. Investigation of the detection capabilities of the fiber and geophone systems is underway and will be presented together with a discussion of the relative merits of the various systems for microseismic monitoring.</p>

scholarly journals ТЕОРЕТИЧНЕ ДОСЛІДЖЕННЯ НАПРУЖЕНО-ДЕФОРМОВАНОГО СТАНУ БАЗОВИХ ПЛИТ УЗРП-16

2020 ◽  
pp. 151-164
Author(s):  
Є. А. Фролов ◽  
Б. О. Коробко ◽  
С. В. Попов
Keyword(s):  
Strain State ◽  
Structural Parameters ◽  
Plate Thickness ◽  
Bending Moment ◽  
Base Plate ◽  
Plate Surface ◽  
Stress Strain ◽  
Stress Strain State ◽  
Study Results ◽  
Base Plates

Theoretical studies of the stress-strain state of base plates, which are the base of the UZRP-16 universal collapsible machines have been done. These machines are used for welding works in machine building industry. The finite element method was applied to solve the problems. Nature of influence of strength and structural parameters on the base plate stress-strain state in operation has been determined, namely: the relations between displacements and stresses arising in the base plates and the bending moment magnitudes have been recorded; the stress-strain state pattern of the base plates has been obtained depending on the place of bending moment application; influence of the conditions for bearing and fastening the plates on their stress-strain state has been investigated; influence of the plate geometric parameters on stress and displacement has been studied; The stress-material and displacement-material relations have been obtained for the plates. Based on the theoretical study results of the base plate stress-strain state, the following have been obtained: stress plots and patterns of deformed surfaces, which are symmetrical with respect to the plate central axes; maximum values of normal and tangential stress components arising in the field of bending moment application; stress on the rectangular base plate surface is 2.1 times higher than the stress on square plate surface under the same conditions of bearing and loading; stresses acting on the plate surfaces and being tensile stresses within the range of 10 to 70 MPa. It was found that the square shape of the plates, according to the stress state, is predominant in relation to the rectangular shape. The optimal condition for bearing is fixing the plates at nine points. For the first time, graphs were drawn for choosing the base plate thickness under action of various operational loads.

scholarly journals Application of Seismic Interferometry by Multidimensional Deconvolution to Earthquake Data Recorded in Malargüe, Argentina

2021 ◽  
Vol 13 (23) ◽  
pp. 4818
Author(s):  
Faezeh Shirmohammadi ◽  
Deyan Draganov ◽  
Mohammad Reza Hatami ◽  
Cornelis Weemstra
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Power Spectra ◽  
Site Amplification ◽  
Seismic Array ◽  
Seismic Interferometry ◽  
Seismic Responses ◽  
Central Chile ◽  
Earthquake Data

Seismic interferometry (SI) refers to the principle of generating new seismic responses using crosscorrelations of existing wavefield recordings. In this study, we report on the use of a specific interferometric approach, called seismic interferometry by multidimensional deconvolution (SI by MDD), for the purpose of retrieving surface-wave responses. In theory, SI by MDD suffers less from irregularities in the distribution of (passive) sources than conventional SI. Here, we confirm this advantage for the application to surface waves originating from regional earthquakes close to Central Chile. For that purpose, we use the Malargüe seismic array in Argentina. This T-shaped array consists of two perpendicular lines of stations, which makes it rather suitable for the application of SI by MDD. Comparing the responses retrieved through SI by MDD to the responses retrieved using conventional SI, we find that the application of SI by MDD results in surface-wave responses that are both more accurate and more stable than surface-wave responses that are retrieved using conventional SI. That is, our results demonstrate that SI by MDD suffers less from non-uniformly distributed earthquakes and differences in the power spectra of earthquake responses. In addition, we show that SI by MDD mitigates the effect of site amplification on the retrieved surface waves.

scholarly journals Monotonic Response of Exposed Base Plates of Columns: Numerical Study and a New Design Method

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 396
Author(s):  
Héctor Díaz ◽  
Eduardo Nuñez ◽  
Claudio Oyarzo-Vera
Keyword(s):  
Numerical Study ◽  
Design Method ◽  
Numerical Models ◽  
Failure Mechanisms ◽  
Plate Thickness ◽  
Base Plate ◽  
Traditional Design ◽  
Current Design ◽  
Bending Loads ◽  
Base Plates

This paper describes a numerical study of the behavior of exposed base plates of columns under the action of axial and bending loads. The aim of this research is to evaluate numerically the failure mechanisms on stiffened and non-stiffened base plates and propose a new design method. The effects of base plate thickness, location of anchor rods, location of stiffeners and tensile strength of anchor rods were considered in the analysis. Sixteen finite elements simulations were performed considering different combinations of the above mentioned parameters. The results show a fragile response in the base plates when high resistance anchor rods are used. The anchor rods worked as fuse elements in base plates with a large thickness or many stiffeners. Additionally, the models with anchor bars located outside of the column flanges showed lower flexural strength and rotational stiffness compared to the models with anchor rods located between column flanges. The simulations showed that the base plate strength was determined by the simultaneous failure mechanisms of two or more components, different to what is stated in current design guides. Finally, the new method is suitable to design base plates with stiffened and not stiffened configurations, which unlike traditional design methods, show a good adjustment with numerical models.

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