Motion Amplification Research Articles

Data-driven adjustments for combined use of NGA-East hard-rock ground motion and site amplification models

Model development in the Next Generation Attenuation-East (NGA-East) project included two components developed concurrently and independently: (1) earthquake ground-motion models (GMMs) that predict the median and aleatory variability of various intensity measures conditioned on magnitude and distance, derived for a reference hard-rock site condition with an average shear-wave velocity in the upper 30 m ( VS30) = 3000 m/s; and (2) a site amplification model that modifies intensity measures for softer site conditions. We investigate whether these models, when used in tandem, are compatible with ground-motion recordings in central and eastern North America (CENA) using an expanded version of the NGA-East database that includes new events from November 2011 (end date of NGA-East data curation) to April 2022. Following this expansion, the data set has 187 events, 2096 sites, and 16,272 three-component recordings, although the magnitude range remains limited (∼4 to 5.8). We compute residuals using 17 NGA-East GMMs and three data selection criteria that reflect within-CENA regional variations in ground-motion attributes. Mixed-effects regression of the residuals reveals a persistent pattern in which ground motions are overpredicted at short periods (0.01–0.6 s, including peak ground acceleration (PGA)) and underpredicted at longer periods. These misfits are regionally variable, with the Texas–Oklahoma–Kansas region having larger absolute misfits than other parts of CENA. Two factors potentially influencing these misfits are (1) differences in the site amplification models used to adjust the data to the reference condition during NGA-East GMM development relative to CENA amplification models applied since the 2018 National Seismic Hazard Model (NSHM), and (2) potential bias in simulation-based factors used to adjust ground motions from the hard-rock reference condition to a VS30 = 760 m/s condition. We provide adjustment factors and their epistemic uncertainties and discuss implications for applications.

Study on Long-Period Ground Motion Amplification Effect of Buried Paleogene Basin Structures in North China

Study on Long-Period Ground Motion Amplification Effect of Buried Paleogene Basin Structures in North China

Regional seismic velocity model for the U.S. Atlantic and Gulf Coastal Plains based on measured shear wave velocity, sediment thickness, and surface geology

The Atlantic and Gulf Coastal Plains (CPs) are characterized by widespread accumulations of low-velocity sediments and sedimentary rock that overlay high-velocity bedrock. Geology and sediment thickness greatly influence seismic wave propagation, but current regional ground motion amplification and seismic hazard models include limited characterization of these site conditions. In this study, a new regional seismic velocity model for the CPs is created by integrating shear wave velocity (VS) measurements, surface geology, and a sediment thickness model recently developed for the CPs. A reference rock VS of 3000 m/s has been assumed at the bottom of the sedimentary columns, which corresponds to the base of Cretaceous and Mesozoic sediments underlying the Atlantic CP and the Gulf CP, respectively. Measured VS profiles located throughout the CPs are sorted into five geologic groups of varying age, and median VS profiles are developed for each group by combining measured VS values within layer thicknesses defined by an assumed layering ratio. Statistical analyses are also conducted to test the appropriateness of the selected groups. A power law model with geology-informed coefficients is used to extend the median velocity models beyond the depths where measured data were available. The median VS profiles provide reasonable agreement with other generic models applicable for the region, but they also incorporate new information that enables more advanced characterizations of site response at regional scales and their effective incorporation into seismic hazard models and building codes. The proposed median velocity profiles can be assigned within a grid-based model of the CPs according to the spatial distribution of geologic units at the surface.

Coupled Rotary Motion in Molecular Motors.

Biological molecular machines play a pivotal role in sustaining life by producing a controlled and directional motion. Artificial molecular machines aim to mimic this motion, to exploit and tune the nanoscale produced motion to power dynamic molecular systems. The precise control, transfer, and amplification of the molecular-level motion is crucial to harness the potential of synthetic molecular motors. It is intriguing to establish how directional motor rotation can be utilized to drive secondary motions in other subunits of a multicomponent molecular machine. The challenge to design sophisticated synthetic machines involving multiple motorized elements presents fascinating opportunities for achieving unprecedented functions, but these remain almost unexplored due to their extremely intricate behavior. Here we show intrinsic coupled rotary motion in light-driven overcrowded-alkene based molecular motors. Thus far, molecular motors with two rotors have been understood to undergo independent rotation of each subunit. The new bridged-isoindigo motor design revealed an additional dimension to the motor's unidirectional operation mechanism where communication between the rotors occurs. An unprecedented double metastable state intermediate bridges the rotation cycles of the two rotor subunits. Our findings demonstrate how neighboring motorized subunits can affect each other and thereby drastically change the motor's functioning. Controlling the embedded entanglement of active intramolecular components sets the stage for more advanced artificial molecular machines.

Scaling artificial heat islands to enhance precipitation in the United Arab Emirates

Abstract. Potential for regional climate engineering is gaining interest as a means of solving regional environmental problems like water scarcity and high temperatures. In the hyper-arid United Arab Emirates (UAE), water scarcity is reaching a crisis point due to high consumption and over-extraction and is being exacerbated by climate change. To counteract this problem, the UAE has conducted cloud-seeding operations and intensive desalination for many years but is now considering other means of increasing water resources. Very large “artificial black surfaces” (ABSs), made of black mesh, black-painted, or solar photovoltaic (PV) panels have been proposed as a means of enhancing convective precipitation via surface heating and amplification of vertical motion. Under the influence of the daily UAE sea breeze, this can lead to convection initiation under the right conditions. Currently it is not known how strong this rainfall enhancement would be or what scale of black surface would need to be employed. This study simulates the impacts at different ABS scales using the WRF-Noah-MP model chain and investigates impacts on precipitation quantities and underlying convective processes. Simulations of five square ABSs of 10, 20, 30, 40, and 50 km sizes were made on four 1 d cases, each for a period of 24 h. These were compared with a Control model run, with no land use change, to quantify impacts. The ABSs themselves were simulated by altering land cover static data and prescribing a unique set of land surface parameters like albedo and roughness length. On all 4 d, rainfall is enhanced by low-albedo surfaces of 20 km or larger, primarily through a reduction of convection inhibition and production of convergence lines and buoyant updrafts. The 10 km square ABS had very little impact. From 20 km upwards there is a strong scale dependency, with ABS size influencing the strength of convective processes and volume of rainfall. In terms of rainfall increases, 20 km produces a mean rainfall increase over the Control simulation of 571 616 m3 d−1, with the other sizes as follows: 30 km (∼ 1 million m3 d−1), 40 km (∼ 1.5 million m3 d−1), and 50 km (∼ 2.3 million m3 d−1). If we assume that such rainfall events happen only on 10 d in a year, this would equate to respective annual water supplies for > 31 000, > 50 000, > 79 000, and > 125 000 extra people yr−1 at UAE per capita consumption rates. Thus, artificial heat islands made from black panels or solar PV offer a means of enhancing rainfall in arid regions like the UAE and should be made a high priority for further research.

Deterministic ground motion modeling with target earthquakes and site effects in eastern Azerbaijan

In the context of assessing seismic hazard, accurately predicting ground motion stands out as a crucial task. Achieving precision in ground motion modeling proves valuable in revealing the actual pattern, even when faced with insufficient data on soil structure, provided there is precise information about the seismic source. This study introduces a methodology for calculating local- and near-field ground motion, expressed in peak ground acceleration (PGA) and intensity values. The deterministic approach is employed, incorporating source characteristics and one-dimensional (1D) site effects. For the chosen test area, the Ismayilli-Shamakhi region on the southeastern slope of the Greater Caucasus in Azerbaijan, two seismic scenarios are investigated: the 1902 Shamakhi earthquake (magnitude M = 6.8) and the November 25, 2000 Baku-Caspian earthquake (two shocks with moment magnitude Mw = 6.08 and 6.18). Different soil types are considered to validate the proposed methodological procedures. The analysis involves the computation of peak ground acceleration motion for two scenario earthquakes: a local-field event with M = 6.8 and a near-field event with Mw = 6.5, representing the average magnitude of the 2000 Baku-Caspian earthquake. The computed peak ground acceleration values are then used to derive intensities. Notably, the 1902 Shamakhi earthquake and the 2000 Baku-Caspian earthquake exhibit similar trends on surface PGA values. The local-field scenario estimates PGA values ranging from 77 to 328 gal, corresponding to MSK-64 scale intensity levels of VII-IX. The near-field scenario, with PGA values ranging from 28 to 62 gal, aligns with MSK-64 intensity levels of VI–VII. In the final assessment, the amplification factor in the study area varies between 0.55 and 0.83. The seismic hazard level is identified as high in the southern and southeastern regions, particularly in areas with soft shallow and medium-depth soils, indicating a high potential for ground motion amplification.

Artificial Flow Guidance Method for Combined Off-Tracking and Stability Improvement for Automated Articulated Vehicles

Abstract This paper considers an integrated control method combining autonomous driving and active steering. By using artificial flow guidance (AFG), the steering at all five axles on a tractor–semitrailer are synchronized for precise low-speed path tracking and improved lateral stability. AFG is a motion planning method which uses velocity vectors to guide the motion of the vehicle; here, two modification on AFG are proposed to form the integrated-AFG which improves the transient performance and generalizes the choice of the tracking points. Simulations rendered in TruckMaker show submillimeter level steady-state off-tracking for a broad speed range, with maximum deviation being 1 cm for a high-speed lane change; amplification of trailer lateral motion is also suppressed, with rearward amplification (RWA) < 1 maintained throughout. This control method is robust to changes in key parameters such as trailer mass and road friction coefficient. The methods presented provide a new foundation for implementing automated freight transportation on highways.

Influence of sediment thickness and reference condition on ground motion amplification in the U.S. Atlantic and Gulf Coastal Plains

Influence of sediment thickness and reference condition on ground motion amplification in the U.S. Atlantic and Gulf Coastal Plains

The effects of low-velocity layer and basin topography in near-field ground motion amplification

The effects of low-velocity layer and basin topography in near-field ground motion amplification

Site Specific Non-Linear Ground Response Analysis and Soil Structure Interaction Study of Newly Constructed Dharahara Tower

This study investigates the seismic performance of the recently reconstructed Dharahara tower, a historically significant monument in Nepal that has experienced damage in past earthquakes and was completely destroyed in the recent Gorkha earthquake. Ground Response Analysis (GRA) and Soil-Structure Interaction (SSI) investigations are conducted to assess its structural behavior. GRA includes free field and structure-influenced analyses, with subsequent comparative assessment. Additionally, 3D non-linear finite element analysis is employed to derive equivalent spring constants representing soil and foundation characteristics, which are incorporated into the SSI analysis. These computed spring constants are used to model support conditions, allowing for an evaluation of the super-structural response. The study also employs non-linear dynamic analysis to compare structural responses between fix-based and spring-based models. The results indicate that the presence of the structure significantly influences surface wave motion amplification in GRA, resulting in peak ground accelerations (PGAs) that exhibit de-amplification in the free field and amplification in the presence of the structure. Furthermore, the introduction of an equivalent spring system in the soil-structure model changes the system's vibration period and damping characteristics, leading to enhanced dynamic response compared to the fixed-base model.

Topographic amplification of seismic ground motion at the broad rift zone of SW Ethiopia

Topographic amplification of seismic ground motion at the broad rift zone of SW Ethiopia

Rigid-Compliant Hybrid Cellular Expansion Mechanisms With Motion Amplification and Superposition

Abstract Motivated by heat dissipation, the rigid-compliant hybrid cellular expansion mechanisms with motion amplification and superposition are proposed in this paper. Compared with existing studies, the expansion mechanism is not only easy to realize the plane tessellation via cellular design due to its regular polygon structure but also has the ability of motion amplification and superposition due to its compliant displacement amplifier and rigid scissors. First, the scheme of expansion mechanisms, especially the working principle of motion amplification and superposition, is introduced. The configuration design of a family of expansion mechanisms is presented, including varying number of edges, concave/convex property, and inner/outer layout. Second, the constraint condition and analytical modeling of relations between output performances of expansion mechanisms and dimensional parameters are carried out. Third, the displacement amplification ratio of expansion mechanisms and output performances of several typical expansion mechanisms when they act as cells to tessellate a plane with a constrained area are analyzed. Finally, the output performances of expansion mechanisms are verified via the finite element analysis. The results show that proposed cellular expansion mechanisms are beneficial for realizing plane tessellation and offer motion amplification and superposition, which provide prospects in the field of mechanism design such as metamaterials.

Influence of the Manipulator Configuration on Vibration Effects

Abstract Vibration analysis of industrial robots is one of the key issues in the context of robotisation of machining processes. Low-frequency vibrations result from flexibility in manipulator joints. Within the scope of the article, a model of a two-link robot manipulator was built. Dynamic equations of motion were formulated to study the influence of the robot arm configuration on vibration effects. Based on numerical simulations, the frequency spectrum of vibrations of the robot’s links was determined, and tests were carried out in a number of configurations, obtaining a map of resonant frequencies depending on the configuration of the manipulator. Experimental studies were then carried out, which confirmed the conclusions from the simulation studies. The results obtained confirm that the positioning of the manipulator’s links has a significant effect on vibration effects. Tests conducted using a vision system with a motion amplification application made it easier to interpret the results. The formulated mathematical model of the manipulator generates results that coincide with the results of experimental studies.

Preliminary analysis of amplified ground motion in Bangkok basin using HVSR curves from recent moderate to large earthquakes

BackgroundThe Bangkok Basin has been known from non-instrumental observations of the local population to be subject to ground motion amplification due to the deep alluvial sediments and basin geometry. This study analyzes available seismic data to confirm that basin effects are significant in the Bangkok Basin. The paper contributes to the evaluation of basin effects by characterizing the engineering ground motion parameters and HVSR curves for the Bangkok basin which produce lengthening of ground motion duration with respect to nearby rock sites, albeit with very low ground motions. For this purpose, we analyzed ground motion records from seismic stations located within the Bangkok alluvial basin from 2007 to 2021. Recorded peak horizontal ground acceleration (PGA) for seismic stations inside the basin always exceeded 1 cm/s2 during eight earthquakes with Mw ≥ 5.5. Of these, two were intraslab events and six were shallow crustal earthquakes. These recorded ground motions shook high-rise buildings in Bangkok even though their epicentral distance exceeded 600 km.MethodsSeveral time and frequency domain analyses (such as analysis of residual, HVSR, Hodogram plots, etc.) are used on the ground motion records in the Bangkok basin to determine the frequency content of recorded ground motion and to demonstrate the significance of surface waves induced by the deep basin in altering the engineering ground motion amplitudes. In addition, centerless circular array microtremor analysis is used to determine the depth of sedimentary basin to the bedrock.ResultsBased on comparisons from those stations located outside the Bangkok basin, we observed the capability of alluvial deposits in the Bangkok basin to amplify ground motion records by about 3 times. We observed that there is a unique site amplification effect between 0.3 and 0.1 Hz due to local surface waves and other moderate amplifications between 2 and 0.5 Hz due to a soft layer like other deep alluvial basins in other metropolitan areas.ConclusionWe noticed that there is a unique site amplification effect between 0.1 and 0.3 Hz and smaller peaks around 2 and 0.5 Hz consistent with expectations for site amplification effects associated with deep basins. Moreover, we noticed the presence of low frequencies content of the surface wave generated within the basin which deserved further studies using the 2D/3D ground motion modelling through basin topography and velocity models.

Development of Synthetic Ground Motion-based Attenuation Relationship for Bihar Region for Seismic Ground Response Analysis Considering Central Seismic Gap

Ground Motion Prediction Equation (GMPE) is one of the significantly important tools to perform the seismic hazards analysis of any region. Therefore, the development of GMPEs at the bedrock level is utmost important especially when the region does not have any earthquake recording stations. The present study discussed the development of a GMPE at bedrock level for the Bihar region based on the stochastic model. The different seismic parameters such as magnitudes (Mw) 4.0‐8.5, spectral periods of 0‐10 s and distances up to 300 km have been considered for the stochastic model. Based on the results, it was found that the stochastic model is capable to predict the ground motion synthetically and the proposed GMPE, for Bihar region, predicts the spectral acceleration in most precise way. Further, the ground motion amplification analysis was carried out using synthetically generated bedrock motion to analyze the effect of soil deposits on the amplification or de‐amplification of the bedrock peak ground acceleration. It was found that that the seismic wave gets amplified at ground level by 10% to 70% from the input motion PGA ranging from 0.175g‐0.435g, indicating amplification and de‐amplification of seismic wave. The maximum spectral acceleration at surface level was also found to be increased by approximately 60%, 56% and 27%, when bedrock input motion of PGA = 0.175g, 0.256g and 0.435g, respectively. Thus, based on the results, it can be stated that the developed GMPE can be used to assess the seismic hazards analysis in Bihar region. Further, it can be suggested that there is a need of the development of a predictive attenuation relationship at the surface level PGA, for Bihar region or any earthquake prone area, incorporating different site classes and regional seismicity since, the seismic wave amplified due to the presence of soil deposits.

Numerical analysis of ground motion amplification coefficient under complex topography

Topographic effect had an obvious influence on the ground motion, but the related regulations were vague in Chinese seismic code. Therefore, this paper explored the influence of topographic feature on the ground motion amplification coefficient (GMAC). The theory of viscoelastic artificial boundary was introduced and used to simulate the ground motion in different topographies. A comparison of the acceleration time-history curves between the simulation and the experiment was performed for illustrating the validity of the simulation method. Then, the influence of isolated topography on the GMAC was analyzed. The results showed that the GMAC was most sensitive to ridge topography. Further, considered with the complexity of real topography, the ground motions of tandem and parallel topographies were researched. The results showed that there was an interaction between adjacent topographies, and that lower-lying topographies should be given more attention due to their stronger earthquake response. Finally, this paper provided the modified suggestion of GMAC based on the researched results.

Dynamic Responses of Concrete-Face Rockfill Dam to Different Site Conditions under Near-Fault Earthquake Excitation

The western region of China is rich in hydropower resources and characterized by unique geological conditions. For the construction or planned construction of high dams in this region, different types of cover layers are formed due to special geological structures, most of which are located in high seismic intensity zones. This study focuses on four different site conditions: hard ground, medium–hard ground, medium–soft ground, and weak ground. By simulating the dynamic response of concrete-face rockfill dams under near-fault earthquake excitation, the vertical settlement of the dam and the attenuation of seismic motion under different site conditions are analyzed. The research findings reveal a consistent trend where the vertical settlement of the dams progressively escalates with increasing dam height across all four site conditions. This settlement phenomenon is especially pronounced in weak ground conditions, posing a potential risk of failure. Furthermore, when subjected to near-fault pulse-type earthquake motions, the existence of weak soil layers significantly dampens the seismic forces experienced by the dam. This finding suggests that the weaker the geological conditions of the site, the more pronounced the attenuation effect of the seismic motion. Additionally, the overburden layers have a noticeable amplification effect on near-fault pulse-type earthquake motion. However, this amplification effect is not significant in weak ground, possibly due to the presence of weak soil layers restricting the propagation and amplification of seismic motion. In conclusion, these research findings have practical significance for the dynamic response of high dam construction in different site conditions in the western region of China. They provide a scientific basis for the design and construction of high dams and serve as a reference for the implementation of seismic mitigation measures and earthquake disaster prevention in engineering projects.

A site amplification model for Switzerland based on site-condition indicators and incorporating local response as measured at seismic stations

AbstractThe spatial estimation of the soil response is one of the key ingredients for the modelling of earthquake risk. We present a ground motion amplification model for Switzerland, developed as part of a national-scale earthquake risk model. The amplification model is based on local estimates of soil response derived for about 240 instrumented sites in Switzerland using regional seismicity data by means of empirical spectral modelling techniques. These local measures are then correlated to continuous layers of topographic and geological soil condition indicators (multi-scale topographic slopes, a lithological classification of the soil, a national geological model of bedrock depth) and finally mapped at the national scale resorting to regression kriging as geostatistical interpolation technique. The obtained model includes amplification maps for PGV (peak ground velocity), PSA (pseudo-spectral acceleration) at periods of 1.0, 0.6 and 0.3 s; the modelled amplification represents the linear soil response, relative to a reference rock profile with VS30 (time-averaged shear-wave velocity in the uppermost 30 m of soil column) = 1105 m/s. Each of these amplification maps is accompanied by two layers quantifying its site-to-site and single-site, within event variabilities, respectively (epistemic and aleatory uncertainties). The PGV, PSA(1.0 s) and PSA(0.3 s) maps are additionally translated to macroseismic intensity aggravation layers. The national-scale amplification model is validated by comparing it with empirical measurements of soil response at stations not included in the calibration dataset, with existing city-scale amplification models and with macroseismic intensity observations from historical earthquakes. The model is also included in the Swiss ShakeMap workflow.

Bladder microenvironment actuated proteomotors with ammonia amplification for enhanced cancer treatment.

Enzyme-driven micro/nanomotors consuming in situ chemical fuels have attracted lots of attention for biomedical applications. However, motor systems composed by organism-derived organics that maximize the therapeutic efficacy of enzymatic products remain challenging. Herein, swimming proteomotors based on biocompatible urease and human serum albumin are constructed for enhanced antitumor therapy via active motion and ammonia amplification. By decomposing urea into carbon dioxide and ammonia, the designed proteomotors are endowed with self-propulsive capability, which leads to improved internalization and enhanced penetration invitro. As a glutamine synthetase inhibitor, the loaded l-methionine sulfoximine further prevents the conversion of toxic ammonia into non-toxic glutamine in both tumor and stromal cells, resulting in local ammonia amplification. After intravesical instillation, the proteomotors achieve longer bladder retention and thus significantly inhibit the growth of orthotopic bladder tumor invivo without adverse effects. We envision that the as-developed swimming proteomotors with amplification of the product toxicity may be a potential platform for active cancer treatment.

Structural design and experimental evaluation of a coarse-fine parallel dual-actuation XY flexure micropositioner with low interference behavior.

This paper proposes a novel two degree of freedom large range coarse-fine parallel dual-actuation flexure micropositioner (CFPDFM) with low interference behavior. First, the structure and working principle of the CFPDFM are introduced. Then, based on the stiffness matrix method, the analytical models of the motion range, input stiffness, and amplification ratio of the mechanism are established. Subsequently, the accuracy of the analytical model is verified by finite element analysis and experiments. Moreover, the dual-servo cooperative drive control strategy is designed to improve the closed-loop positioning ability of the CFPDFM. Finally, the CFPDFM experimental system is built to verify the plane trajectory tracking performance. The results reveal that the micropositioner can achieve a total range of 3.02 × 3.11mm2, a resolution of ≤40nm, low interference performance of coarse and fine actuators, good cross-axis decoupling, and planar complex trajectory tracking performance, while possessing a compact structure. It can be used in many plane positioning situations requiring large range and high precision.