Amplification Effect Research Articles

Synergistic effects of Arctic amplification and Tibetan Plateau amplification on the Yangtze River Basin heatwaves

Extreme heatwaves pose a significant threat to a wide range of environmental, ecological, and social systems. The rapid warming of the Arctic and the Tibetan Plateau (TP), which are the most prominent features in the Northern Hemisphere in the context of climate change, has significantly influenced mid-latitude extreme events in recent decades. This study utilizes observational data and numerical simulations to demonstrate that the variations in Arctic amplification (AA) and TP amplification (TA) play a crucial role in the interannual variability of summer heatwaves (HWs) in the Yangtze River Basin (YRB) (HWs_YRB) region. The HWs_YRB is associated with a zonally oriented barotropic high-pressure system anchored over the YRB region. The spatial distribution and intensity of the HWs_YRB are impacted by the synergistic effects of AA and TA, via a meridional atmospheric tripole pattern and double jets over East Asia. Furthermore, AA primarily impacts the geographical extent of the HWs_YRB, while TA plays a critical role in determining the intensity of the HWs_YRB. Our findings provide an innovative perspective on the linkage between the pronounced warming observed in the Arctic and TP and the occurrence of summer HWs_YRB, enhancing our comprehension of the climatic consequences of the rapid changes in these two geographical regions.

A comparative analysis of risk factors influencing crash severity between full-time and part-time riding-hailing drivers in China

ABSTRACT Ride-hailing is increasingly important in urban public transportation, yet research on its traffic safety remains limited. This study examined risk factors for crash severity among ride-hailing drivers, including demographics, financial burden, phone usage, fatigue, and risky driving behaviors. Data were collected from 2,182 drivers via a self-reported survey. Recognizing potential differences between full-time and part-time drivers, the data were divided accordingly, and two Bayesian network models were generated. The results indicated that both types of drivers suffer from heavy financial burdens and severe fatigue, with certain factors related to risky behaviors or phone usage increasing the likelihood of serious crashes. However, the specific risk factors leading to severe crashes varied between the two groups. Furthermore, the study confirmed that several combinations of risk factors exhibit nonlinear amplification effects on crash severity across different driver groups. These findings may support the design of evidence-based interventions to mitigate crash severity among ride-hailing drivers.

Dynamic response and seismic vulnerability assessment of the near-fault steep slope

Existing field data demonstrates that structures situated near faults, such as slopes, dams, and bridges, are particularly vulnerable to damage. Near-fault ground motions exhibit marked disparities from their far-field counterparts, necessitating thorough investigation. This study conducts a comprehensive analysis of ground motion characteristics utilizing response spectra, Hilbert-Huang Transform (HHT), and marginal spectra to discern near-fault pulse-like ground motions (PLGMs), near-fault non-pulse-like ground motions (NPGMs), and far-fault ground motions (FFGMs). PLGMs distinguished by their heightened energy content, typically induce more pronounced amplification effects compared to NPGMs and FFGMs. Employing an efficacy criterion, optimal intensity measures (IMs) are identified and linked to dynamic response, referred to as engineering demand parameters (EDPs). Velocity-based IMs demonstrate substantial correlations across diverse ground motion types for both plastic volume ratio (PVR) and crest displacement (Dc). Lastly, probabilistic seismic demand models are leveraged to establish seismic vulnerability curves for steep slopes exposed to PLGMs and NPGMs. Notably, with Dc as the EDP, the exceedance probabilities associated with the three IMs under PLGMs generally surpass those under NPGMs. This underscores the propensity of PLGMs to trigger larger displacements in slopes, rendering them more prone to failure.

Design and study of the flow section of a variable microchannel reformer based on the coupling law of reforming with flow, heat and mass transfer

In the amplification mode, microscale reforming reactions are controlled by the transfer rate. To avoid the amplification effect, the process coupling mechanism in the microchannel reactor must be studied to take full advantage of its precise control. This paper studies the coupling effect between the flow process and the reforming process in the microchannel and constructs a computational model of the flow coupling. A study was conducted on the influence of the coupling effect on the conversion rate, based on a combination of reliability verification and experiments. The following conclusions were obtained: the coupling effect in the reactive flow field was quantified based on the characteristic time of the flow process and the reaction process (Da number), and the microchannel was divided into three parts. The methanol conversion rate of the burst-expansion scheme was increased to more than 6%, and the USAER (unit surface area enhancement rate) reached 7.7. The USAER of the protrusion-expansion scheme can reach 8.342, with a potential for an 10% increase in conversion rate. The distribution of the three-segmented variable cross-section has the most effective regulation effect. The USAER of the protrusion-expansion scheme reaches 9.11, with a conversion rate that can be increased by 7%.

Controllable synthesis of heterostructured CuO–ZnO microspheres for NO2 gas sensors

Nitrogen dioxide (NO2) sensors experience the drawback of requiring high operating temperatures because of the low charge transfer ability of gas-sensing materials. Herein, an advanced NO2 sensor resistant to interference is designed using the interfacial energy barriers of a hierarchical CuO/ZnO composite. With the benefits of abundant desirable defect features, and the amplification effect of heterojunctions, the sensor based on CuO/ZnO composite with 10% Cu(CH3COO)2·H2O (S2) shows outstanding performance in terms of faster response and recovery time (1.8-fold/1.1-fold), higher response (3.1-fold), and lower power consumption (140℃ decrease) compared to the pristine ZnO sensor. Furthermore, the composite sensor exhibits long-term stability and reproducibility, indicating the potential promise of CuO/ZnO heterojunctions in interference-resistant detection of low-concentration NO2 in real applications. This study not only provides a rational solution to designing advanced gas sensors by tuning the interfacial energy barriers of heterojunctions, but also provides a fundamental understanding of CuO structures in the gas-sensing field.

Organic-inorganic hybrid piezotronic bipolar junction transistor for pressure sensing

With the rapid development of the Internet of Things (IoTs), wearable sensors are playing an increasingly important role in daily monitoring of personal health and wellness. The signal-to-noise-ratio has become the most critical performance factor to consider. To enhance it, on the one hand, good sensing materials/devices have been employed; on the other hand, signal amplification and noise reduction circuits have been used. However, most of these devices and circuits work in an active sampling mode, requiring frequent data acquisition and hence, entailing high-power consumption. In this scenario, a flexible and wearable event-triggered sensor with embedded signal amplification without an external power supply is of great interest. Here, we report a flexible two-terminal piezotronic n-p-n bipolar junction transistor (PBJT) that acts as an autonomous and highly sensitive, current- and/or voltage-mediated pressure sensor. The PBJT is formed by two back-to-back piezotronic diodes which are defined as emitter-base and collector-base diodes. Upon force exertion on the emitter side, as a result of the piezoelectric effect, the emitter-base diode is forward biased while the collector-base diode is reverse biased. Due to the inherent BJT amplification effect, the PBJT achieves record-high sensitivities of 139.7 kPa-1 (current-based) and 88.66 kPa-1 (voltage-based) in sensing mode. The PBJT also has a fast response time of <110 ms under exertion of dynamic stimuli ranging from a flying butterfly to a gentle finger touch. Therefore, the PBJT advances the state of the art not only in terms of sensitivity but also in regard to being self-driven and autonomous, making it promising for pressure sensing and other IoT applications.

Detuning effects for heat-current control in quantum thermal devices.

Navigating the intricacies of thermal management at the quantum scale is a challenge in the pursuit of advanced nanoscale technologies. To this extent, theoretical frameworks introducing minimal models mirroring the functionality of electronic current amplifiers and transistors, for instance, have been proposed. Different architectures of the subsystems composing a quantum thermal device can be considered, tacitly bringing drawbacks or advantages if properly engineered. This paper extends the prior research on thermotronics, studying a strongly coupled three-subsystem thermal device with a specific emphasis on a third excited level in the control subsystem. Our setup can be employed as a multipurpose device conditioned on the specific choice of internal parameters: heat switch, rectifier, stabilizer, and amplifier. The exploration of the detuned levels unveils a key role in the performance and working regime of the device. We observe a stable and strong amplification effect persisting over broad ranges of temperature. We conclude that considering a three-level system, as the one directly in contact with the control temperature, boosts output currents and the ability to operate our devices as a switch at various temperatures.

Performance analysis of a novel single-flywheel resettable-inertia damper with eddy-current damping

The clutching inertia model presents an ideal Bang-Bang control approach, but it is challenging to realize practically through passive means. In this paper, a single-flywheel resettable-inertia damper (SRID) is proposed on the basis of the clutching inertia model. This device is implemented with a rack-and-pinion system, a right-angle gearbox system, and a flywheel-mounted eddy-current damping system. Initially, a mechanical analysis model of this device is established according to its working mechanism. Subsequently, comparative analyses are performed on the performance of SRID in a single degree-of-freedom (SDOF) structure compared to viscous dampers (VDs) subjected to harmonic and seismic excitations. The results show that the SRID can achieve a comparable control effect as VDs with a much smaller need for the damping coefficient, reflecting a damping amplification effect over 100 times. The SRID is effective in controlling peak displacement and absolute acceleration responses, especially for long-period structures. Moreover, the control performance is significantly improved with increasing magnetic induction intensity.

Experimental study of a WEC array-floating breakwater hybrid system in multiple-degree-of-freedom motion

Installing an array of wave energy converters (WECs) on an existing breakwater is viable to reduce the high cost and improve the reliability of wave energy applications. The interaction between WECs and floating breakwater under multi-degree-of-freedom motion is crucial but not well investigated, especially the impact of WECs on the mooring system of the breakwater. This article fills this gap by experimentally studying a hybrid system consisting of a rectangle floating breakwater and an array of oscillating body WECs. The interactions between the WEC and the breakwater, the effect of the WEC bottom shape on the hybrid system, and the performance of the hybrid system in waves with different nonlinearities are investigated. Results indicate that the wave amplification effect of the breakwater improves the wave energy conversion performance of the WEC by up to 324.6%. As the WEC absorbs wave energy, the mooring forces of the breakwater in the pitch and surge directions decrease by up to 19.8% and 47.4%, respectively. When the incident wave height increases, the energy extraction performance of the hybrid system improves while the wave attenuation performance decreases. This study provides a reference for the practical application of WEC-breakwater hybrid systems and test data for the validation of numerical methods.

Analysis of the Dynamic Behavior of Multi-Layered Soil Grounds

The ground consists of many layers of soil with different properties. The propagation speed and path of seismic waves are affected by different soil layers. It is necessary to understand that layered soil exhibits different dynamic behaviors and responses under the action of seismic waves. This study utilized weathered soil and silica sand as materials to create multi-layered soil conditions with varying degrees of compaction. By conducting a 1 g shaking-table test on multi-layered soil, the interactions and influences between different soil layers under different earthquake conditions were observed. The approach of our numerical analysis aimed to complement the experimental results and provide an in-depth understanding of the dynamic behavior of multi-layered soil surfaces during seismic events. The acceleration results achieved with the ABAQUS and DEEPSOIL models for multi-layered soil were in good agreement with the experimental results. By comparing the stress–strain curves, the deformation mechanisms under different constitutive models in the numerical analysis were studied. The results of this study show that the amplification effect of seismic waves is related to the number of soil layers and the degree of compaction of the soil layers. This indicates that multi-layered soil ground and the behavior of the soil layers play an important role in the propagation and impact of seismic waves, and this amplification effect is of great significance in the design of actual seismic disaster risk assessments.

1748-P: NMDA Receptor Is Involved in Amplification Effects of Glycine on Insulin Secretion

1748-P: NMDA Receptor Is Involved in Amplification Effects of Glycine on Insulin Secretion

IL-12 induces a B cell-intrinsic IL-12/IFNγ feed-forward loop promoting extrafollicular B cell responses.

While some infections elicit germinal centers, others produce only extrafollicular responses. The mechanisms controlling these dichotomous fates are poorly understood. We identify IL-12 as a cytokine switch, acting directly on B cells to promote extrafollicular and suppress germinal center responses. IL-12 initiates a B cell-intrinsic feed-forward loop between IL-12 and IFNγ, amplifying IFNγ production, which promotes proliferation and plasmablast differentiation from mouse and human B cells, in synergy with IL-12. IL-12 sustains the expression of a portion of IFNγ-inducible genes. Together, they also induce unique gene changes, reflecting both IFNγ amplification and cooperative effects between both cytokines. In vivo, cells lacking both IL-12 and IFNγ receptors are more impaired in plasmablast production than those lacking either receptor alone. Further, B cell-derived IL-12 enhances both plasmablast responses and T helper 1 cell commitment. Thus, B cell-derived IL-12, acting on T and B cells, determines the immune response mode, with implications for vaccines, pathogen protection and autoimmunity.

Kinematic response of a pile within a soil slope to SH wave excitation

It is widely recognized that the topography of a slope can significantly enhance the magnitude of seismic waves. Nevertheless, the mechanism behind the topographic amplification on the kinematic response of a pile within a soil slope remains unclear. Consequently, a newly rigorous method is employed to investigate the kinematic response of a pile within a soil slope. The proposed method which combines the Wave Function Expansion (WFE) method and the Beam on Dynamic Winkler Foundation (BDWF) model advances the rigorous theoretical study for the kinematic response of a pile on slope from the pseudo-static analysis to the frequency-domain analysis. The proposed solution well captures the kinematic response of a piles within a slope. The parametric analysis focuses on investigating the influence of slope topographic amplification effects on pile vibration under different incident frequencies, slope gradients, and pile-to-soil modulus ratios. The results indicate that steep slopes and high pile-to-soil modulus ratios lead to higher topographic amplification effects, with specific frequencies significantly amplifying the kinematic response of pile within a slope. Nonetheless, as the pile located beyond twice the length of the slope, the amplification effect notably diminishes.

Preparation of hierarchical microgroove textures on the surface of Al-based wicks by roller pressing and laser scanning irradiation

Fabrication of high-performance heat pipe wicks has become a major challenge due to the increase of heat dissipation requirements for electronic devices. In this paper, we propose a two-step method for the preparation of aluminum liquid-absorbing wicks with hierarchical groove structures by roller pressing and laser irradiation techniques. The effects of laser fluence and velocity on the groove morphology, wettability and capillary effect of the aluminum wicks with hierarchical grooves processed by laser scanning are investigated. The study demonstrates that sub-scale grooves with a period of 20 μm can be created on the surface of the aluminum wick using a laser fluence of 7.166 J/cm2, scanning velocities of 560 mm/s and 630 mm/s, and a pulse distance of 1 μm. The surface roughness of the irradiated aluminum wick was increased and energy dispersive spectroscopy tests showed an increase in the oxygen content of the machined surface, resulting in a surface amplification effect and the formation of a large number of hydrogen bonds in contact with the liquid. Capillary rise experiments demonstrate that hierarchical microgrooves enhance capillary action on the surface of the aluminum wick more effectively than single-scale grooves. This is due to the pumping effect in microgrooves and the diffusion effect in Ω-grooves. The hierarchical microgroove prepared under the above parameters had a capillary rise height of 88.5 mm and a capillary rise speed of 5.5 mm/s. This work proposes a method for producing high-performance wicks that are both efficient and cost-effective.

Dynamic amplification of rail tracks in high-speed lines: Exploring train effects and impact of ground treatment

When the train circulation speed is much lower than the critical speed of the track-ground system, problems with dynamic amplification effects are purely theoretical. However, the situation can change if a new high-speed line, with a higher operation speed, is planned for a site with soft soils. In such cases, it may be necessary to assess the importance and consequences of the critical speed phenomenon on safety and operational costs of the railway track. A practical measure involving the ground treatment may contribute to an improvement of the system behaviour. This measure is based on replacing a portion of the natural soil with stiffer materials or by employing grouting. The current paper provides numerical evidence as the soil reinforcement significantly improves the dynamic behaviour of the ground-track system. It is also possible to conclude that localized ground reinforcement below the track yields a response similar to extending the reinforcement over a larger area. This conclusion is particularly interesting for engineering practice and for numerical/semi-analytical analysis. The study of the effect of the train geometry on the critical speeds of the train-track system is also carried out. However, the main conclusion is that the definition of the critical speed as the value that induces larger amplification due to the passage of a single load is a conservative approach. Finally, it was observed that an approach based on the calculation of the dispersion curves enhances an adequate estimation of the system’s critical speed.

Directional amplification across the San Jacinto fault zone, CA

SUMMARY The amplitude, frequency and polarization of ground motion at the surface can be affected by the local geology. While low-velocity sediments and fill can amplify ground motions in certain frequency ranges, the low velocities found in fault zones can also produce prominent wavelets. In this paper, we provide further evidence that polarization of ground motion can be affected by the geological fabric in fault zones that have sustained significant brittle deformation. Aside from the well-known effect of fault-trapped waves in the low-velocity zone with polarization azimuths parallel to the fault strike, the effect of stiffness anisotropy was recently recognized with polarization azimuths at high-angle to the fault strike and orthogonal to the locally predominant fracture field in the fault damage zone. To clarify further such features, we investigate directional amplification effects across the San Jacinto fault zone in Southern California using seismic data recorded by permanent seismic stations and dense across-fault arrays. We observe three main polarization trends. The first trend parallel to the fault strike is ascribed to fault-trapped waves along the low-velocity zone, in agreement with several studies in the last decade in the same region. The second and third trends are orthogonal to the orientation of R and T Riedel planes, respectively. They are related to the stiffness anisotropy in densely fractured rocks in the damage zone, which are more compliant orthogonal to their fractures. At some locations the two effects are superimposed, occurring in different and distinct frequency ranges. Directional amplification at rock sites can be important for expected ground motion and seismic hazard. However, in seismic engineering the current prescriptions of seismic codes do not account for amplification effects at rock sites at frequencies of engineering interest.

Nonlinear dynamic characteristics of double tumblers

The oscillation mechanism of tumblers differs from traditional mass-spring-dampers. This work studies the complicated dynamic behaviors of a double tumbler on a curved surface. The theoretical model of the double tumbler is established, and the equations of motion based on the Lagrange equation are derived. The effects of the geometric parameters on the dynamic responses are analyzed numerically. The experiment is also conducted to validate the theoretical model of double tumblers. The results show that two eigenmodes of the double tumbler are the synchronous and bidirectional swings, respectively. Due to the amplification effect of double tumblers on the dynamic responses, the amplitudes of the inner tumbler are larger than that of the outer tumbler. The resonance peaks and the peak frequencies of the swing angles can be changed significantly by adjusting geometric parameters. In addition, the double tumblers can exhibit periodic and quasi-periodic oscillations with the increase in the excitation amplitude. The unique dynamic characteristics of the double tumblers show great potential for the design and application of low-frequency devices, such as absorbers and energy harvesters.

Ultrahigh-Speed 3D DNA Walker with Dual Self-Protected DNAzymes for Ultrasensitive Fluorescence Detection and Intracellular Imaging of microRNA.

Herein, a dual self-protected DNAzyme-based 3D DNA walker (dSPD walker), composed of activated dual self-protected walking particles (ac-dSPWPs) and track particles (TPs), was constructed for ultrasensitive and ultrahigh-speed fluorescence detection and imaging of microRNAs (miRNAs) in living cells. Impressively, compared with the defect that "one" target miRNA only initiates "one" walking arm of the conventional single self-protected DNAzyme walker, the dSPD walker benefits from the secondary amplification and spatial confinement effect and could guide "one" target miRNA to generate "n" secondary targets, thereby initiating "n" nearby walking strands immediately, realizing the initial rate over one-magnitude-order faster than that of the conventional one. Moreover, in the process of relative motion between ac-dSPWPs and TPs, the ac-dSPWPs could cleave multiple substrate strands simultaneously to speed up movement and reduce the derailment rate, as well as combine with successive TPs to facilitate a large amount of continuous signal accumulation, achieving an ultrafast detection of miRNA-221 within 10 min in vitro and high sensitivity with a low detection limit of 0.84 pM. In addition, the DNA nanospheres obtained by the rolling circle amplification reaction can capture the Cy5 fluorescence dispersed in liquids, which achieves the high-contrast imaging of miRNA-221, resulting in further ultrasensitive imaging of miRNA-221 in cancer cells. The proposed strategy has made a bold innovation in the rapid and sensitive detection as well as intracellular imaging of low-abundance biomarkers, offering promising application in early diagnosis and relevant research of cancer and tumors.

Enhancing performance and structural integrity of cemented paste backfill: Rheological behavior, strength characteristics, and microstructural dynamics

In order to improve the mechanical properties of backfill, steel slag and straw fiber were used as materials to prepare backfill. The law of sand-cement ratio, mass concentration, steel slag content and straw fiber on strength and rheological parameters of backfill was analyzed by orthogonal test method, and the influence mechanism of steel slag content and straw fiber on physical properties of backfill was revealed. The results show that mass concentration exerts the most substantial impact on rheological parameters, emerging as a significant determinant. Moreover, the yield stress diminishes with escalating tailings-cement ratio, while it escalates with higher mass concentration, steel slag content and straw fiber content. Augmenting the tailings-cement ratio and steel slag content serves to impede the amplification effect of mass concentration on yield stress. Notably, the tailings-cement ratio emerges as the most influential factor affecting the uniaxial compressive strength (UCS) of the backfill, albeit the UCS diminishes with rising tailings-cement ratio. Elevating the mass concentration and steel slag content can counteract the debilitation caused by an increase in the tailings-cement ratio on the UCS of the backfill. Furthermore, heightened mass concentration can bolster the reinforcing impact of steel slag content on early UCS. The increase of tailings-cement ratio increases the size and range of the void inside the backfill, subsequently leading to the degradation of its macroscopic compressive strength. The adhesion between straw fiber and mortar matrix constitutes a pivotal factor in improving the integration of backfill, whereas steel slag contributes to improving the mechanical properties by enhancing the distribution of void structures within the backfill. This research not only offer data support and scientific guidance for the design of backfill ratio parameters but also facilitate the broader application of straw fiber and steel slag in mine backfilling operations.

Analysis of Amplification Effect and Optimal Control of the Toggle-Style Negative Stiffness Viscous Damper

This paper proposes a new toggle-style negative stiffness viscous damper (TNVD), and evaluates the performance of the TNVD with the displacement amplification factor (fd) and the energy dissipation factor (fE). Firstly, the composition and characteristics of the TNVD are introduced. Subsequently, the displacement amplification factor is introduced to evaluate the displacement amplification ability of the TNVD, and it is decomposed into a geometric amplification factor and an effective displacement coefficient. Then, based on the geometric amplification factor and effective displacement coefficient, the correlation between the TNVD’s displacement amplification ability and inter-story deformation is studied, and an improved TNVD is proposed. By the comparison of the finite element calculation results, it is found that the improved TNVD can utilize the assumption of small structural deformation. After that, the impacts of plentiful aspects, such as the length of the lower connecting rod, the horizontal inclination angle of the lower connecting rod, the inter-story deformation limit, the cross-sectional area of the connecting rod, the damping coefficient, and the negative stiffness on the fd and fE of the improved TNVD, are expounded. The research results show that when the length of the TNVD’s lower connecting rod remains unchanged, the fd and fE present a trend of increasing first and then decreasing with the increase in the horizontal inclination angle of the lower connecting rod. When the inter-story deformation is fixed, there exists an optimal lower connecting rod’s length that satisfies a specific relationship to achieve the optimal geometric amplification factor of the TNVD. By adjusting the damping parameters of the TNVD, we can obtain a better effective displacement coefficient greater than 0.95 in the proposed target region. Meanwhile, the fd and fE increase with the decrease in the negative stiffness. An optimization strategy for the improved TNVD has been proposed to ensure that the TNVD has the characteristics of operational safety, ideal displacement amplification capability, and energy dissipation capability. Furthermore, a multi-objective control design method with an additional improved TNVD structure is proposed. The vibration reduction effect of the structure with the improved TNVD and the effectiveness of the optimization strategy are verified through examples.