Artificial Wave Research Articles

Errors of structural seismic responses caused by frequency filtering based on seismic wave synthesis

In order to meet the requirements of shake tables, frequency filtration of seismic input is usually performed before tests. Aiming to study the error of seismic analysis caused by filtering, the artificial seismic waves before and after filtering with four different waveforms were synthesized in this paper. Based on a spring-friction isolation system, the effects of filtering on seismic responses with various spring constants, friction coefficients and envelope functions were investigated. The results show that the maximum acceleration of the pure friction system is not affected by filtering while the error of maximum relative displacement caused by filtering can reach 60% and decreases with the increment of the friction coefficient. For the spring-friction system, the friction coefficient corresponding to a smaller structural seismic response is exactly the most unfavorable friction coefficient for filtering error and hence needs more attention during shaking table tests. Filtering errors based on different waveforms have the same tendency despite some slight differences owing to the different responses.

Shaking table test on multi-dimensional seismic response of structure and nuclear power equipment coupled system

Structure and nuclear power equipment coupled system in nuclear power plant has complex dynamic interaction under seismic action. In order to study the seismic response of coupled system and assess seismic capacity of nuclear power equipment, shaking table test on coupled system by multi-dimensional seismic action was carried out. The natural frequency and damping ratio of the structure and nuclear power equipment were measured by two dynamic characteristic tests before and after the test. Furthermore, the test also included five operating basis earthquakes and one safe shutdown earthquake by using the artificial seismic waves as seismic inputs. The test results show that the dynamic amplification effect of the coupled system is obvious, and acceleration amplification factor of the equipment in the coupled system is about two times of the equipment directly connected to the shaking table in the X direction, between one and two times in the Y and Z direction. Compared with the structure, the dynamic response of the equipment in the coupled system also has a certain degree of amplification effect. In addition, the dynamic characteristics of structure and equipment change little. The equipment works well under all the test conditions, meeting the seismic requirements.

SHAKING TABLE TESTS ON THE SEISMIC RESPONSE CHARACTERISTICS OF DOUBLE-COLUMN PIERS WITH SHEAR BEAMS

Shaking table tests were carried out to study the influences of shear beams on the seismic response of double-column piers that were designed to support the girder of a full cable-stayed bridge model. The double-column pier with shear beams included two columns and five shear beams equally installed between the two columns. A full cable-stayed bridge model of 1/70-scale that included the pier (a double-column pier and a double-column pier with shear beams), tower, girder, pile group, and artificial soil was designed and tested on a shaking table array. The seismic response characteristics were compared between the double-column piers with and without shear beams when they were subjected to various earthquake waves of various frequency contents, such as the artificial, El Centro, and Mexico City waves. The experimental results show that the maximum strains at the bottom of the double-column pier with shear beams were less than those of the double-column pier under the artificial, El Centro wave, and Mexico City waves of various shaking amplitudes. The additional shear beams significantly mitigated the strain responses at the bottom of the double-column pier, and decentralized the inner force of the columns. The maximum accelerations at the bottom of the double-column pier with shear beams are 1.4-1.8 times those of the shaking table when the bridge model was subjected to the artificial, El Centro, and Mexico City waves with 0.1 g, 0.15 g, and 0.2 g. The pile-soil-structure interaction significantly affected the seismic response of the double-column pier with shear beams and increased its longitudinal acceleration responses. The seismic responses, such as the acceleration, displacement, and strain responses of the double-column pier with and without shear beams were significantly affected by the frequency spectral characteristics of the various earthquake waves. The extent of the influence was dependent on the relationship between the frequency contents of the earthquake waves and the frequency spectral characteristics of the piers.

Three-dimensional linear seismic analysis of normal concrete gravity dam

The three-dimensional linear finite element model is established for the bottom outlet dam section of concrete gravity dam. Mode-superposition response spectrum method and the massless foundation time history method are adopted to analyze the static and dynamic comprehensive stress response and displacement response of the dam under the action of the standard response spectrum of the design earthquake or the corresponding artificial wave under the action of design earthquake and check earthquake. The results show that the dam works well in seismic condition. In addition, the influence of radiation damping of infinite foundation on the dynamic response of the dam section under different seismic waves is analysed. By comparing the dynamic and static comprehensive stress changes of the dam, it shows that after considering the radiation damping effect of the infinite foundation, the dynamic response of the dam body is significantly reduced.

Sensitivity Analysis of Adjustable River Surf Waves in the Absence of Channel Drop

Most artificial river wave technologies require a drop in the riverbed to generate recreational surf waves; herein a new technology is introduced that can be used on a flat bed. The mechanism includes an adjustable ramp, transition and kicker, which can be independently manipulated to generate a surf wave. A 3-D numerical model of the described mechanism is developed based on a prototype Kananaskis River wave in Alberta, Canada, and is calibrated by means of physical model data. Numerical experiments are conducted to demonstrate sensitivity of the wave to geometric features of each element of the structure in different hydraulic conditions such as flowrate and tailwater depth. Results are presented in dimensionless form to be generalizable and describe the wave behavior. It is shown that the ramp slope, the heaviest and most expensive element of the structure, has a minimal effect on the wave profile, while the tailwater depth, kicker geometry and kicker position can significantly augment and accelerate the wave.

The Biocompatibility of Wireless Power Charging System on Human Neural Cells

The progress in technology and science leads to the invention and use of many electrical devices in the daily lives of humans. In addition to that, people have been easily exposed to increased newly generated artificial electromagnetic waves. Exponential use of modern electronic devices has automatically led to increase in electromagnetic wave exposure. Therefore, we constructed the prototype of wireless power charging system to study the biocompatibility of electromagnetic field (EMF) generated by this system on various human cell lines. There are many studies indicating the negative bio-effect of EMF on various types of cells, such as induction of apoptosis. From the other point of view, these effects could rather be beneficial in the way, that they could eliminate the progress of various diseases or disorders. For that reason, we compared the impact of EMF (87 kHz, 0.3–1.2 mT, 30 min) on human normal as well as cancer cell lines based on morphological and cellular level. Our results suggested that EMF generated by wireless power charging systems does not have any detrimental effect on cell morphology, viability and cytoskeletal structures of human neural cells.

Dynamic Performance Analysis of Ancient Buildings Based on Soil-Structure Interaction

This paper takes Guangyue Tower as the research object and uses ANSYS software to establish three finite element models of its upper timber structure, timber structure and high platform foundation and wooden structure, high platform foundation and soil mass. Through modal analysis, it is concluded that when the soil-structure interaction is considered, the natural frequency of the structure is reduced, and its influence on the high-order natural frequency of the structure is greater than the influence on the low-order natural frequency. Select El-Centro wave, Taft wave and artificial wave to analyze the dynamic performance. The results show that only considering the wood structure or wood structure and the high platform will make the calculated displacement smaller, so the influence of the existence of the foundation soil on the superstructure should be considered.

Seismic collapse fragility of low-rise steel moment frames with mass irregularity based on shaking table test

The collapse risk of building structures has been one of the major factors causing casualties and huge economic losses for earthquake disaster prevention. This paper presents a shaking table test on low-rise steel moment frames with consideration of mass irregularity in the elevation direction. The frames are subjected to naturally observed and artificial seismic waves. As indicated from the test results, the specimen with the irregularity of additive-mass (additional 5% of the roof mass) on the top floor showed considerable amplification on the acceleration and drift responses at the bottom storey when subjected to over-design earthquakes. A numerical model with degraded stress–strain relation is built in terms of fiber elements and calibrated by test results. Incremental dynamic analyses are performed to evaluate the probabilities exceeding three limit states related to immediate occupancy, life safety, and collapse prevention. The seismic fragility curves through a suite of near-fault ground motions in the Uemachi area of Osaka are obtained for the numerical models with and without mass irregularity on the roof, and the vertical mass irregularity tends to play significant roles in the seismic design for collapse prevention.

Rancang Bangun Pembangkit Listrik Tenaga Gelombang Laut Menggunakan Sistem Oscillating Water Column

Ocean wave power plant is one of the plants that uses sea waves as the main energy. Although the amount of energy is abundant, in Indonesia the use of sea waves as electricity generators is still small. This is due to the lack of human resources to manage the wave energy of sea water. Many research studies on the Oscillating Water Column have been carried out, but it is only limited to a potential or feasibility study to be installed on the coast. Therefore, the focus of this research is to design a sea wave power plant with an oscillating water column system. The working process of the tool begins by adjusting the pwm to drive the motor power window which is connected to the wave arm. When the wave arm moves back and forth, it will produce artificial ocean waves. Artificial waves in the chamber produce compressed air, the air produced is used to rotate the turbine blades that have been connected to the generator to produce electrical energy. The greatest voltage and current is obtained when the wind speed reaches 7.7 m / s and the largest pulley rotating speed reaches 31,9 rpm at the 17 cm water level, which is 3.03 V DC and 6,07 mA. The test results prove that the potential of water waves can be used to generate electricity The development of the capacity of ocean wave power plants can be done by changing the dimensions of the turbines and increasing the capacity of the generator.

Vibration Testing and Evaluation of 35-kV km-Level Domestic Second-Generation High-Temperature Superconducting Power Cable in Shanghai, China

The 35-kV km-level domestic high-temperature superconducting (HTS) power cable project in Shanghai, China, is expected to be deployed in 2021. Facing the complex operating environment in the metropolitan area, such as the vibration excitation from the subway, pile driving, and seismic activities, the vacuum degree, sealability, and insulation performance of the HTS cables may be affected by the unavoidable mechanical perturbations. The response to the potential vibration excitation is a key factor for the safety and stability of the HTS cables in operation. Therefore, this paper conducts a set of vibration testings for the HTS cable under four kinds of vibration conditions, which include the subway vibration, pile-driving vibration, typical earthquake vibration, and Shanghai artificial wave vibration. Results show that the leakage and outgassing rate of the HTS cable is 1.3×10−6 Pa m3/s at a static state, and increases to 1.4×10−6 Pa m3/s after the vibration testing. The HTS cable exhibits insignificant changes after the vibration testings in the dielectric spectrum examination. The HTS cable can keep its function after the vibration testing that possibly occurred in the metropolitan area.

Using the Carotazh Method to Determine the Electrical Characteristics of the Earth’s Subsoil

Logging is a detailed study of the structure of the well incision by descent and ascent of a geophysical probe. It is often used to determine the electrical conductivity of terrestrial depths. To do this, the sides of the well deepen the electrodes, and they are fed into the depths of a constant electric current. However, if you use natural or artificial electromagnetic waves, it becomes possible to determine the dielectric permeability of terrestrial rocks at depth. To do this, the surface impedance is first measured on the surface of the earth, and then by measuring at a certain frequency of the electromagnetic field in the well hole, the electrical conductivity and dielectric permeability of terrestrial rocks are calculated by fairly simple formulas. Such measurements can be carried out by standard measuring systems, adding only a narrow frame with wire winding to measure the magnetic field.

A micro-kinetic model of enhanced foam stability under artificial seismic wave

Abstract To get a deeper understanding on the synergistic enhancement effect of low frequency artificial seismic wave on foam stability, a micro-kinetic model of enhanced foam stability under low frequency artificial seismic wave is established based on a vertical liquid film drainage model and elastic wave theory. The model is solved by non-dimensional transformation of the high order partial differential equations and a compound solution of implicit and explicit differences and is verified to be accurate. The foam film thickness, surfactant concentration distribution and drainage velocity under the action of low frequency artificial seismic wave are quantitatively analyzed. The research shows that low-frequency vibration can reduce the difference between the maximum and minimum concentrations of surfactant in the foam liquid film at the later stage of drainage, enhance the effect of Marangoni effect, and improve the stability of the foam liquid film. When the vibration frequency is close to the natural frequency of the foam liquid film, the vibration effect is the best, and the best vibration frequency is about 50 Hz. The higher the vibration acceleration, the faster the recovery rate of surfactant concentration in the foam liquid film is. The higher the vibration acceleration, the stronger the ability of Marangoni effect to delay the drainage of foam liquid film and the better the foam stability is. It is not the higher the vibration acceleration, the better. The best vibration acceleration is about 0.5 times of gravity acceleration. Reasonable vibration parameters would greatly enhance the effect of Marangoni effect. The smaller the initial concentration of surfactant, the better the vibration works in enhancing Marangoni effect.

First 5-year multicentric clinical trial experience with the HeartMate 3 left ventricular assist system

The HeartMate 3 (HM3) left ventricular assist system (Abbott, Abbott Park, IL) is a durable mechanical circulatory support device with unique features comprising a magnetically levitated rotor with a wide blood flow path and artificial pulse wave. 1 Schmitto JD Hanke JS Rojas SV Avsar M Haverich A First implantation in man of a new magnetically levitated left ventricular assist device (HeartMate III). J Heart Lung Transplant. 2015; 34: 858-860 Abstract Full Text Full Text PDF PubMed Scopus (129) Google Scholar

Trapped Modes in Armchair Graphene Nanoribbons

Scattering on an ultralow potential in an armchair graphene nanoribbon is studied. Using the continuous Dirac model and including a couple of artificial waves in the scattering process, described by an augmented scattering matrix, a condition is derived for the existence of a trapped mode. Threshold energies, where the multiplicity of the continuous spectrum changes, are considered, and it is shown that a trapped mode may appear for energies slightly less than a threshold and its multiplicity does not exceed one. For energies that are higher than a threshold, there are no trapped modes, provided that the potential is sufficiently small.

Экспериментальные исследования влияния периодической модуляции течения на развитие возмущений в пограничном слое скользящего крыла при числе Маха 2,5

The results of experimental studies on the impact of periodic flow modulation on the development of natural disturbances and artificial localized wave packets in the boundary layer of a swept wing with a leading edge swept angle of 40 degrees at a Mach number M = 2.5 are presented. The boundary layer was modulated using periodic roughness on the model surface. Artificial wave packets were generated by a pulsed glow discharge. Hot-wire anemometer measurements showed that, according to the experimental conditions, periodic modulation of the boundary layer leads to the stabilization of the development of controlled localized disturbances and to an increase in the growth of natural disturbances.

О ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ ЭМИССИИ МИКРОСЕЙСМ ПРИ ПОИСКЕ НЕФТЕГАЗОВЫХ МЕСТОРОЖДЕНИЙ НА ПРИМЕРЕ ЧАЙКИНСКОЙ ПЛОЩАДИ

The article presents the results of microseismic mapping of Chaykinskaya area using standard seismic gathers. Offsets more than 2 km and time interval from 3.5 s and, i.e. after the registration of primary artificial waves are used. Increasing of microseisms intensity (0-30 Hz) compared to intervals before first brakes was revealed. The anomaly of microseismic noise at the elevation in the northeastern part of the area confirmed by an inheritance of the anomaly on two parallel profiles and a profile crossing them was identified. This anomaly correlates in the area with a trap detected by the aero-gamma-spectrometry method. The investigation results of the microseismic emission can be used in an integrated interpretation of geophysical data in oil and gas exploration.

Reliability of Piping System Input by Nonstationary Artificial Wave

Reliability of Piping System Input by Nonstationary Artificial Wave

Laboratory sources of gravitational waves

We consider the possibility of generating and subsequently detecting artificial gravitational waves in a laboratory based on different approaches. As one of the methods for creating gravitational waves, we investigate oscillations of the ions of the crystal lattice of a dielectric under the influence of high-power laser radiation. The characteristics of gravitational waves obtained by this method are compared with the results of using the other approaches as well.

Seismic Analysis for Nuclear Power Safety Related Bridge

For the first time in China’s nuclear power industry, an in-plant emergency access bridge is proposed to be constructed. This bridge inside the nuclear power plants will serve as an important emergency evacuation route and as an access port for rescue operations in the power plant under potential accident conditions. Thus, the seismic safety of the bridge is a critical matter. This paper, which is based on a real engineering project, builds a refined finite element (FE) model for a continuous girder bridge-foundation structure. A seismic wave input method based on a nonlinear artificial boundary is used to suggest a reasonable size for a truncated foundation area for the purposes of dynamic simulations. The paper further discusses the influences of the nonlinear viscous artificial boundary and other various seismic wave input methods on the dynamic response of the bridge. Results show that compared to the traditional viscous artificial boundary, a nonlinear viscous artificial boundary has a better absorbing effect. The error of the bending moments at the bottom of piers improves from around 3.2% to around 1.9%. At the same time, compared to the “bottom wave + lateral free” and “bottom wave + lateral shear” of two seismic wave input methods, the nonlinear wave input method can generate results with higher accuracy. With the nonlinear input method, the error of the bending moment at the bottom of piers improves from around 13.7% to around 1.9%.

Experimental study on acceleration response laws of shallow-buried bias tunnels with a small distance

Based on the similarity theory, a physical testing model with scale of 1:10 was designed and fabricated. The Wenchuan wave (WC-XZ), Darui artificial wave (DR-XZ) and Kobe wave (K-XZ) were adopted as excitation waves which was XZ directions (horizontal and vertical loading at the same time). A series of shaking table tests were carried out to study the effect of the types, directions and peaks acceleration of the seismic waves on the acceleration response laws of the shallow-buried bias tunnels with small distance. The results show that: (1) in the horizontal direction, the types of the seismic waves have a little effect on the acceleration response, but the law is opposite with Kobe wave being the most serious, followed by Darui artificial wave and Wenchuan wave in the vertical direction. (2) The existing slope has a significant effect on the acceleration response of the right hole which is different from that of the left hole. (3) The acceleration response of the tunnel in the vertical direction is more severe than that of the horizontal direction and the acceleration amplification factors in vertical direction are is generally 1.02-3.94 times that of the horizontal direction. (4) in the seismic design of tunnel, different seismic measures should be adopted in different directions. The results have a significant reference for the anti-seismic design of the tunnel.