Master curves for the response of layered systems to compressional seismic waves

1967 ◽  
Vol 57 (3) ◽  
pp. 515-543 ◽  
Author(s):  
Luis M. Fernandez
Keyword(s):  
Seismic Waves ◽  
Transfer Functions ◽  
Point Of View ◽  
Time Lags ◽  
Master Curves ◽  
Layer System ◽  
Crust And Upper Mantle ◽  
Response Characteristics ◽  
Families Of Curves ◽  
Short Time

abstract The layers of the earth's crust act as a filter with respect to seimic energy arriving at a given station. Consequently the motion recorded at the surface depends not only on the frequency content of the source and on the response characteristics of the recording instrument, but also on the elastic parameters and thicknesses of the transmitting layers. This latter dependence is the basis for a method of investigating the structure of the crust and upper mantle. To facilitate this investigation a set of master curves for the transfer functions of the vertical and horizontal component of longitudinal waves and their ratios is presented. The calculation of these curves is in terms of a dimensionless parameter. This calculation allows one to group the curves corresponding to different crustal models into families of curves. The characteristics of these curves are discussed from the point of view of their “periodicity” in the frequency domain and of their amplitude in order to investigate the influence of the layer parameters. Considerations, either of constructive interference or of Fourier analysis of a pulse multiply reflected within the layer system, reveal that the amplitudes of the transfer curves depend on the velocity contrasts at the interfaces of the system. The “periodicity” or spacing of the peaks depends on the time lags between the first arrivals and the arrivals of the different reverberations. Closely spaced fluctuations correspond to large-time lags, and widely spaced fluctuations to short-time lags.

scholarly journals Vibroacoustic Assessment of an Innovative Composite Material for the Roof of a Coupe Car

2021 ◽  
Vol 11 (3) ◽  
pp. 1128
Author(s):  
Nunziante Cascone ◽  
Luca Caivano ◽  
Giuseppe D’Errico ◽  
Roberto Citarella
Keyword(s):  
Composite Material ◽  
Transfer Functions ◽  
Realistic Model ◽  
Point Of View ◽  
Damping Capacity ◽  
Geometry Structure ◽  
Fiberglass Composite ◽  
New Material ◽  
Static Rigidity ◽  
Innovative Material

The objective of this paper is the vibroacoustic evaluation of an innovative material for a sports car roof, aiming at replacing fiberglass composite materials. Such evaluation was carried out using numerical and experimental analysis techniques, with cross-comparison between the corresponding results. The innovative material under analysis is a composite material, with a thermoplastic polypropylene matrix and reinforcement made of cellulose fibers. In order to validate the virtual dynamic modeling of the new material, the inertance on different points of some sheets made of the material under analysis was evaluated by an in-house made experimental activity, performed in the CRF (Fiat Research Center) test room, and cross-compared with corresponding results from a numerical analysis performed with the MSC Nastran software. Then, a realistic model of the car roof of the Alfa Romeo 4C car, made with the new material, was implemented and analyzed from the vibroacoustic point of view. The mere switch to the new material, with no changes in the geometry/structure of the car roof, did not allow preserving the original values of static rigidity, dynamic rigidity, and configuration of modal shapes. For this reason, a geometric/structural optimization of the component was performed. Once the new geometry/structure was defined, a vibroacoustic analysis was carried out, checking for a possible coupling between the fluid cavity modes and the structure car body modes. Finally, the vibroacoustic transfer functions to the driver’s ear node were assessed, considering two different excitation points on the structure. The excellent damping capacity of the proposed material led to an improvement in the vibroacoustic transfer functions and to a reduction in the weight of the pavilion.

scholarly journals Selective capture of carbon dioxide from hydrocarbons using a metal-organic framework

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Omid T. Qazvini ◽  
Ravichandar Babarao ◽  
Shane G. Telfer
Keyword(s):  
Carbon Dioxide ◽  
Density Functional ◽  
Metal Organic Framework ◽  
Density Functional Theory Calculations ◽  
Time Lags ◽  
X Ray Crystallography ◽  
Metal Organic ◽  
Adsorption Of Co ◽  
Short Time ◽  
Organic Framework

AbstractEfficient and sustainable methods for carbon dioxide capture are highly sought after. Mature technologies involve chemical reactions that absorb CO2, but they have many drawbacks. Energy-efficient alternatives may be realised by porous physisorbents with void spaces that are complementary in size and electrostatic potential to molecular CO2. Here, we present a robust, recyclable and inexpensive adsorbent termed MUF-16. This metal-organic framework captures CO2 with a high affinity in its one-dimensional channels, as determined by adsorption isotherms, X-ray crystallography and density-functional theory calculations. Its low affinity for other competing gases delivers high selectivity for the adsorption of CO2 over methane, acetylene, ethylene, ethane, propylene and propane. For equimolar mixtures of CO2/CH4 and CO2/C2H2, the selectivity is 6690 and 510, respectively. Breakthrough gas separations under dynamic conditions benefit from short time lags in the elution of the weakly-adsorbed component to deliver high-purity hydrocarbon products, including pure methane and acetylene.

scholarly journals Reconciling Lagrangian Diffusivity and Effective Diffusivity in Contour-Based Coordinates

2019 ◽  
Vol 49 (6) ◽  
pp. 1521-1539
Author(s):  
Yu-Kun Qian ◽  
Shiqiu Peng ◽  
Chang-Xia Liang
Keyword(s):  
Time Lag ◽  
Effective Diffusivity ◽  
Delta Function ◽  
Spreading Rate ◽  
Particle Dispersion ◽  
Small Scale ◽  
Time Lags ◽  
Conservative Tracer ◽  
Stirring Effect ◽  
Short Time

AbstractThe present study reconciles theoretical differences between the Lagrangian diffusivity and effective diffusivity in a transformed spatial coordinate based on the contours of a quasi-conservative tracer. In the transformed coordinate, any adiabatic stirring effect, such as shear-induced dispersion, is naturally isolated from diabatic cross-contour motions. Therefore, Lagrangian particle motions in the transformed coordinate obey a transformed zeroth-order stochastic (i.e., random walk) model with the diffusivity replaced by the effective diffusivity. Such a stochastic model becomes the theoretical foundation on which both diffusivities are exactly unified. In the absence of small-scale diffusion, particles do not disperse at all in the transformed contour coordinate. Besides, the corresponding Lagrangian autocorrelation becomes a delta function and is thus free from pronounced overshoot and negative lobe at short time lags that may be induced by either Rossby waves or mesoscale eddies; that is, particles decorrelate immediately and Lagrangian diffusivity is already asymptotic no matter how small the time lag is. The resulting instantaneous Lagrangian spreading rate is thus conceptually identical to the effective diffusivity that only measures the instantaneous irreversible mixing. In these regards, the present study provides a new look at particle dispersion in contour-based coordinates.

ERRORS CONVERSION ON TRANSFER FUNCTIONS OF MEASUREMENT AND CONTROL

2021 ◽  
Vol 4 ◽  
pp. 92-104
Author(s):  
Valentin Bahatskyi ◽  
◽  
Aleksey Bahatskyi ◽  
Keyword(s):  
Transfer Functions ◽  
Systematic Errors ◽  
Step Function ◽  
Control Device ◽  
Point Of View ◽  
Correct Operation ◽  
Analog To Digital ◽  
Analog To Digital Conversion ◽  
And Control ◽  
Measurement And Control

Currently, the measurement of electrical and non-electrical quantities is performed using analog-to-digital conversion channels, which consist of analog signal conditioning circuits and analog-to-digital converters (ADC) of electrical quantities into a digital code. The paper considers the case when the defining errors of the measurement and control channel are systematic errors of the ADC. The reliability of measurements is assessed by their errors, and the reliability of control - by the likelihood of correct operation of the control device. In our opinion, evaluating the reliability of such similar processes as measurement and control using different criteria seems illogical. The aim of the work is to study the effect of systematic errors of an analog-to-digital converter on the errors of parameter control depending on the type of conformity functions and the width of the control window, as well as the choice of the resolution of the ADC for various control tasks. The paper analyzes the transfer functions of measurement and control. It is shown that they are formed using step functions. It is proposed to use not a step function as a control transfer function, but other functions of conformity to the norm, for example, a linear function or functions of higher orders. In this case, the control result is assessed not according to the criterion of the probability of correct operation, but using the control error. Analyzed from the point of view of reconfiguring the errors of the line, parabolic and state parabolic functions of the norms for the development of changes windows in control. A recommendation has been given for the selection of functions for the conformity of standards and for the distribution of analog-to-digital conversions for industrial control enterprises.

scholarly journals Use And Comparison of Topis And Electre Methods In Personnel Selection

2018 ◽  
Vol 22 ◽  
pp. 01021 ◽  
Author(s):  
Bilgin Şenel ◽  
Mine Şenel ◽  
Gizem Aydemir
Keyword(s):  
Personnel Selection ◽  
Selection Process ◽  
Minimum Cost ◽  
Point Of View ◽  
Blue Collar Worker ◽  
Automotive Company ◽  
Worker Selection ◽  
Electre Method ◽  
The Right ◽  
Short Time

One of the most important function of human resources is personnel selection process. This process should be done professionally, in a short time and with minimum cost. After personnel selection process, performance of the hired person is very important for the permanence and success of the company. From this point of view, the aim of this study is to select a personnel among the candidates efficiently, with minimum cost and within a short time in one of the leading companies of Turkey in automotive sector. In order to select the right personnel all criterias which has great impact on blue collar worker selection was decided and these criterias are weighted. From the candidate pool of automotive company, appropriate candidates were selected by using TOPSIS AND ELECTRE method which are multi-criteria decision making methods

scholarly journals THE VALUATION OF SELF-FUNDING INSTALMENT WARRANTS

2017 ◽  
Vol 20 (04) ◽  
pp. 1750025
Author(s):  
J. N. DEWYNNE ◽  
N. EL-HASSAN
Keyword(s):  
Monte Carlo ◽  
Finite Difference ◽  
Multiple Scales ◽  
Correction Term ◽  
Approximate Solutions ◽  
Fair Value ◽  
Small Time ◽  
Point Of View ◽  
First Order Correction ◽  
Short Time

We present two models for the fair value of a self-funding instalment warrant. In both models we assume the underlying stock process follows a geometric Brownian motion. In the first model, we assume that the underlying stock pays a continuous dividend yield and in the second we assume that it pays a series of discrete dividend yields. We show that both models admit similarity reductions and use these to obtain simple finite-difference and Monte Carlo solutions. We use the method of multiple scales to connect these two models and establish the first-order correction term to be applied to the first model in order to obtain the second, thereby establishing that the former model is justified when many dividends are paid during the life of the warrant. Further, we show that the functional form of this correction may be expressed in terms of the hedging parameters for the first model and is, from this point of view, independent of the particular payoff in the first model. In two appendices we present approximate solutions for the first model which are valid in the small volatility and the short time-to-expiry limits, respectively, by using singular perturbation techniques. The small volatility solutions are used to check our finite-difference solutions and the small time-to-expiry solutions are used as a means of systematically smoothing the payoffs so we may use pathwise sensitivities for our Monte Carlo methods.

scholarly journals A Universal Porous Adsorbent for the Selective Capture of Carbon Dioxide

2019 ◽  
Author(s):  
Omid Taheri Qazvini ◽  
Shane G. Telfer
Keyword(s):  
Carbon Dioxide ◽  
Natural Gas ◽  
Porous Materials ◽  
Noncovalent Interactions ◽  
Metal Organic Framework ◽  
Time Lags ◽  
Guest Molecules ◽  
Energy Penalty ◽  
Carbon Dioxide Co2 ◽  
Short Time

<div>Efficient and sustainable methods for carbon dioxide (CO2) capture are essential. Its atmospheric</div><div>concentration must be reduced to meet climate change targets, and its remediation from chemical</div><div>feedstocks and natural gas is vital. While mature technologies involving chemical reactions that trap the</div><div>CO2 do exist, they have many drawbacks. Porous materials with void spaces that are complementary in</div><div>size and electrostatic potential to CO2 offer an alternative. In these materials, the molecular CO2 guests</div><div>are trapped by noncovalent interactions, hence they can be recycled by releasing the CO2 with a low</div><div>energy penalty. Porous materials that are selective towards CO2 when it is present with an array of</div><div>competing gases are challenging to produce. Here, we show how a metal-organic framework, termed</div><div>MUF-16 (MUF = Massey University Framework), is a ‘universal’ adsorbent for CO2 that sequesters</div><div>CO2 from a broad palette of gas streams with record selectivities over competing gases. The position of</div><div>the CO2 molecules captured in the framework pores was determined crystallographically to illustrate</div><div>how complementary noncovalent interactions envelop the guest molecules. The pore environment has a</div><div>low affinity for all other gases, which underpins the benchmark selectivity of MUF-16 for CO2 over</div><div>methane, hydrogen and acetylene. Breakthrough gas separations under dynamic conditions benefit from</div><div>short time lags in the elution of the weakly-adsorbed component to deliver a repertoire of high-purity</div><div>products. MUF-16 is an inexpensive, robust, easily regernarable and recyclable adsorbent that is</div><div>universally applicable to the removal of CO2 from sources such as natural gas, syngas and chemical</div><div>feedstocks.</div>

scholarly journals The role of the oral myologist with orthognathic surgery -- A patient/therapist's point of view

1986 ◽  
Vol 12 (2) ◽  
pp. 13-14
Author(s):  
Joy Moeller
Keyword(s):  
Surgical Treatment ◽  
Muscle Function ◽  
Orthognathic Surgery ◽  
Muscle Fibers ◽  
Point Of View ◽  
Short Time

Introduction: The trauma of orthognathic surgery on muscle function has frequently been overlooked by oral surgeons. The attitude of many surgeons is that the muscle fibers will adapt to the new structure in a short time. The purpose of this paper is to dispute this attitude and to address the need for the oral rnyologist to assume an important role in the healing and post-surgical treatment of the patient.

Seismic ground-response studies in Olympia, Washington, and vicinity

1990 ◽  
Vol 80 (5) ◽  
pp. 1057-1078
Author(s):  
K. W. King ◽  
A. C. Tarr ◽  
D. L. Carver ◽  
R. A. Williams ◽  
D. M. Worley
Keyword(s):  
Seismic Waves ◽  
Hard Rock ◽  
Puget Sound ◽  
Open Pit ◽  
Site Conditions ◽  
Ground Response ◽  
Response Characteristics ◽  
Seismic Ground Response ◽  
Geological Units ◽  
The City

Abstract Relative seismic ground-response characteristics in the cities of Olympia, Lacey, and Tumwater, Washington, were determined from analysis of instrumentally recorded ground motion induced by blasts at an open-pit coal mine near Centralia, Washington. A ground-response function (GRF), defined as the ratio of Fourier spectral amplitudes at an alluvium site to spectral amplitudes on hard rock, is a measure of amplification of seismic waves by localized site conditions. GRF values in three frequency bands (0.5 to 1.0 Hz, 1.0 to 2.0 Hz, and 2.0 to 4.0 Hz) were compared with observed Modified Mercalli (MM) intensities from the 29 April 1965, Puget Sound earthquake and with mapped surficial geologic units. Typically, the GRF values relate well with the surficial geological units. In addition, MM intensities within the V to VII range appear to be directly related to the frequencies within the 0.5 to 4.0 Hz bandwidth such that MM V intensity sites had a lower GRF value in the 2.0 to 4.0 Hz bandwidth as compared to the 0.5 to 2.0 Hz bandwidth, and the MM VII intensity sites had higher GRF values in the 2.0 to 4.0 Hz bandwidth as compared to the 0.5 to 2.0 Hz bandwidth. The set of GRF values determined for the city of Olympia and its vicinity should be useful in formulating a theoretical relative ground-response model for the southern Puget Sound area.

An Alternative Carcass Design to Prevent Flow-Induced Pulsations in Flexibles

2021 ◽  
Author(s):  
N. González Díez ◽  
S. P. C. Belfroid ◽  
T. Iversen Solfeldt ◽  
C. Kristiansen
Keyword(s):  
Pressure Drop ◽  
Theoretical Analysis ◽  
Numerical Simulations ◽  
Steel Strip ◽  
Point Of View ◽  
Theoretical Point ◽  
Adjacent Structures ◽  
Operational Constraints ◽  
Short Time ◽  
Fatigue Failures

Abstract Flow-induced pulsations (FLIP) are pressure oscillations generated inside of flexibles used in dry gas applications that can cause unacceptable vibration levels and eventually failure of equipment. Because of the design of inner layer of the flexibles, the carcass, the frequency of the pulsations is high, potentially leading to fatigue failures of adjacent structures in a relatively short time. The traditional carcass is made of a steel strip formed into an interlocked s-shape in a series of preforming and winding steps. To enable bending of the pipe, gaps are present between each winding with a shape that can cause FLIP. The gaps can be reduced, and the profiles optimized, but they will always be able to generate FLIP at a certain gas velocity. To remove the risk of FLIP in dry gas projects and ensure that operator does not get operational constraints, an alternative carcass design has been developed. This is essentially a conventional agraff carcass but with an additional cover strip to close the gap, making the resulting carcass nearly smooth bore in nature. With a smooth bore this carcass can be used for flexibles which have a risk of FLIP or to produce pipes with a lower internal roughness. This alternative design can be manufactured and can therefore build on the large manufacturing and design experience of the traditional strip carcass. This alternative carcass technology is to undergo a full qualification process, in which the risk of flow induced pulsations is an essential component. With the investigated alternative carcass design, the cavities present in the traditional agraff designs are covered. It is expected that the risk due to the appearance of FLIP is therefore eliminated. Theoretical analysis, numerical simulations and scaled experiments are used to explore the risk for the alternative technology to create FLIP. The theoretical analysis is based on existing knowledge and literature. The numerical simulations and scaled tests are done to generate direct evidence for the end statements resulting from the qualification process. Numerical simulations follow the power balance method presented by the same authors in earlier papers. The same applies to the techniques used for the scaled tests. The main outcome of the qualification presented here are the pressure drop performance and the anti-FLIP capabilities of the design. The new design performs significantly better than the nominal design carcass for the same purpose. The pressure drop coefficients found are close to those expected for a normal, non-corrugated pipe, and thus the recommendation given by the API 17J standard does not apply to this design. The pressure drop coefficient is dependent on the installation direction of the flexible with respect to the flow. No signs of FLIP are found for the nominal design of the investigated carcass technology. This is the case for either installation direction. This is explained from a theoretical point of view, but also numerical and experimental evidence are provided.

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