Amplification Mechanism Research Articles

Pressure amplification effect of initial compression waves in circumferential cracks of high-speed railway tunnel linings

Spalling of concrete blocks from tunnel linings is a severe defect in high-speed railway tunnels (HSRTs). The amplified initial compression wave (ICW) in circumferential cracks induced by high-speed trains may be the main cause of crack propagation and concrete block formation. To investigate the aerodynamic amplification effect of the ICW in circumferential cracks, tunnel-crack models are established and solved based on the unsteady viscous k–ε turbulence method. A scaled indoor experiment is carried out to verify the reliability of the calculation method. The characteristics of amplified pressure and corresponding mechanisms are analyzed and revealed. Three influential parameters, including the crack width, crack depth, and train velocity, are analyzed and discussed in detail. The main conclusions are as follows: (1) the maximum amplified pressure in a typical circumferential crack is 5.68 times that of the ICW. (2) The maximum power spectrum density (PSD) of the aerodynamic pressure at the crack tip is 91.04 times that at the crack mouth. The crack tip suffers most from the aerodynamic impact of the fluctuating component of pressure waves, whereas the crack mouth is most susceptible to the average component. (3) The train velocity is the most influential parameter on the maximum pressure at the crack tip, followed by the crack depth. The power function with an exponent of 2.3087 is applicable for evaluating the relationship between the maximum pressure and train velocities. (4) The train velocity and crack depth are most influential parameters to the maximum PSD. The relationship between the maximum PSD and the crack widths, crack depths, and train velocities can be reasonably described by the power function. (5) The mechanism of pressure amplification is as follows: first, the superposition of the internal energy possessed by air molecules near crack surfaces. Second, the increase in the internal energy of air near the crack tip because of the gradually narrowing space. The results of our research may be applicable in analyzing the cracking behavior of tunnel lining cracks and preventing the spalling of concrete blocks in HSRTs.

Magnetic Circular Dichroism in Archean Stratospheric Oxygen: Enantiomeric Excess of Amino Acids Produced in Volcanic Plumes.

While there is consensus that Archean atmosphere was anoxic with O2 pressure, p(O2) <10-6 PAL (present atmospheric level) at sea-level, evidence suggests that p(O2) at stratospheric altitudes of 10-50 km was orders of magnitude higher, a result of photodissociation of CO2 by UVC sunlight and incomplete mixing of O2 with other gases. Molecular O2 is paramagnetic due to triplet ground state. Magnetic circular dichroism (MCD) by stratospheric O2 is examined in earth's magnetic field and shows maximum circular polarization │(I+ - I-)│ at altitude of 15-30 km (I+/I- is intensity of left/right circularly polarized light). While (I+ - I-)/(I+ + I-) is small (~10-10), it is an unexplored source of enantiomeric excess (EE) by asymmetric photolysis of amino acid precursors produced in volcanic eruptions. The precursors reside in stratosphere for periods of over a year due to relative absence of vertical transport. Due to negligible thermal gradient across equator, they are trapped in the hemisphere where they are produced, with interhemispheric exchange time of over a year. The precursors diffuse through altitudes of maximum circular polarization before getting hydrolyzed on ground to amino acids. Enantiomeric excess of ~10-12 is calculated for precursors and amino acids. While small, this EE is orders of magnitude higher than predicted (~10-18) by parity violating energy differences (PVED) and could be the seed for growth of biological homochirality. Preferential crystallization (PC) is described as a plausible mechanism for amplification of solution EE of some amino acids from 10-12 to 10-2, for period of several days.

Pressure amplification mechanism for airborne ultrasound: Air-DPLUS

Airborne ultrasound is a promising technology in food and agriculture industries. However, its practical application is limited by its high energy attenuation and short propagating distance. In this work, we introduced a new system called Air-DPLUS (airborne double-parabolic-reflector wave-guided ultrasonic transducer), consisting of a focusing mechanism combined with a cylindrical airborne transducer. We evaluated the output pressure and its axial distribution in simulations and experiments. Under transient and continuous excitation, our prototype Air-DPLUS amplified the maximum pressure 6.9 and 24.4 fold, respectively, in comparison with the use of an airborne transducer alone.

Two types of morphing wing designs based on multistage displacement amplification mechanisms

Two types of morphing wing designs based on multistage displacement amplification mechanisms

Do sovereign credit rating events affect the foreign exchange market? Evidence from a treatment effect analysis

AbstractWe estimate the effect of sovereign credit rating events on the foreign exchange market. Using entropy balancing—a treatment effect methodology that properly addresses the possible self‐selection and endogeneity biases related to rating events—we find robust evidence that a positive (negative) sovereign credit rating event significantly increases (decreases) on average exchange rates, with a larger magnitude for negative events. This effect remains significant under flexible (but not under fixed) exchange rate regimes, and displays asymmetries related to the size of the rating event: in particular, only negative large (i.e., above one notch) rating events trigger a significant response of exchange rates. Lastly, we unveil important nonlinearities related to the initial value of the rating, suggesting a possible amplification mechanism: the impact of positive (negative) rating events is stronger in absolute value if ratings are initially high (low).

Design and development of a 3-DoF robotic wrist joint with tension amplification mechanism

Design and development of a 3-DoF robotic wrist joint with tension amplification mechanism

Development of a novel XZ workpiece vibration generator for cooperative vibration cutting of hierarchical grating structures

This paper presents a novel piezoelectrically-driven XZ workpiece vibration generator (WVG) enabling the cooperative vibration cutting, which serves as a promising alternative for machining hierarchical micro/nano-structured surfaces. The WVG features a double symmetric configuration and the integration of two flexural lever mechanisms and an eight legs Z-shaped mechanism for dual-stage displacement amplification as well as decoupled 2D motion modulation. By utilizing the matrix-based stiffness modeling and Lagrange principle with motion properties of the piezoelectric actuators treated as boundary conditions, the kinetostatics and dynamics of proposed WVG are analytically described and verified using finite element analysis. The experimental performance assessments of proposed WVG show a working space of 44.7 μm × 38.9 μm with a positioning resolution less than 20 nm in both motion directions. The capability of delivering harmonic elliptical as well as non-harmonic triangular and trapezoidal motion trajectories has been demonstrated. In addition, the developed WVG was integrated into a newly cooperative vibration cutting system for one-step machining of hierarchical grating structures. The cutting performances of three kinds of hierarchical grating structures demonstrate not only the feasibility and flexibility of proposed cooperative vibration cutting process but also the accuracy and robustness of the developed WVG mechanism.

Analytical and experimental investigation of a motion amplified rotational friction damper

This article introduces a novel rotational friction damper to enhance energy dissipation capacity of structures. The proposed damper contributes to force and energy dissipation capacities by utilizing friction torques between steel plates and aluminum pads (disks) that rotate relative to each other. The novelty of the damper stems from the motion amplification mechanism, which is achieved by the small initial angle between the structural element and the steel plate arms of the damper. Furthermore, friction damping occurs in all joints of the mechanism as opposed to solely at the middle joint, which is the case for the existing friction dampers that are placed at beam-column joint regions. The proposed damper is compact and particularly effective for joints where small gap openings occur, such as precast post-tensioned structural systems. The amplification mechanism is specifically designed to magnify the rotations due to this gap opening. Experiments, conducted on the damper with varying parameters, show that proposed damper’s performance is very satisfactory in terms of both force and energy dissipation capacities.

Modeling simulation on amplifying magnetic fields in supernova remnants with an intense laser

Local magnetic field enhancement in supernova remnants (SNRs) is a natural laboratory for studying the amplification effect of turbulent magnetic fields. In recent years, high-power laser devices have gradually matured as a tool for astronomical research that perfects observations and theoretical models. In this study, a model of the amplification effect of the turbulent magnetic field in SNRs by an intense laser is simulated using the radiation magnetohydrodynamic simulation program. We investigate and compare the evolutionary processes of unstable turbulence under different initial disturbance modes, directions, and intensities of external magnetic fields and obtain the magnetic energy spectrum and magnetic field magnification. The results demonstrate that the fluid motion associated with Rayleigh–Taylor instability will stretch the environmental magnetic field significantly, with an intensity amplified by two orders of magnitude. The environmental magnetic field perpendicular to the laser injection direction is decisive during magnetic field amplification which is necessary to clarify the physical mechanism of magnetic field amplification in SNRs. Furthermore, it will deepen the understanding of the interstellar magnetic field’s evolution. The results also establish a reference for laser-driven magnetized plasma experiments in a robust magnetic environment.

Cascade amplification strategy based on ultra-thin graphdiyne and CRISPR/Cas for real-time detection of tumor biomarker

As an important cancer markers, the sensitive, portable and highly specific detection of miRNA-141 is impendency. Currently, self-powered electrochemical sensors based on enzyme biofuel cells still difficult to be applied for rapid and sensitive detection for miRNAs. In this work, a sensitivity self-powered biosensor constructed by ultra-thin graphdiyne nanomaterials with good thermal stability and high electron mobility, combination of 3D DNA Walker mediated CRISPR/Cas12a cascade signal amplification strategy. In the linear range of 0.5–10000 fM, the detection limit is as low as 0.14 fM. Most importantly, the sensor platform can achieve real-time detection of miRNA-141 through smartphone. Finally, the relevant electrode reaction and signal amplification mechanism of sensing platform is explored, and the accurate determination of low content miRNA in complex biological samples is realized, which is expected to provide an effective method for the early diagnosis and prognosis of cancer patients.

Synergistic Signal Amplification-Initiated Innovative Self-Powered Photoelectrochemical Aptasensing: An Ingenious Photocathode Activated by the High-Light-Harvesting Photoanode.

Exploiting ingenious photoelectrodes and innovative signal amplification strategies has the potential to achieve high sensitivity in self-powered cathodic photoelectrochemical (PEC) analysis. In this work, a novel self-powered PEC sensing platform was constructed by integrating a synergistic signal amplification of an ingenious photocathode with a high light-harvesting photoanode. In the dual photoelectrode-based PEC system, the amplified photocurrent signals were induced by a synergistic enhancement: (1) the photocurrent of the BiOBr photocathode was improved by the incorporation of nitrogen-doped graphene; (2) the photocurrent of the self-powered sensor was activated by the high-light-harvesting Bi2S3-C3N4 photoanode. Subsequently, the rational mechanism for synergistic signal amplification was investigated. For the construction of the sensing interface, an aptamer was introduced as the recognition element to specifically capture the streptomycin (STR) target. Under optimal conditions, the constructed self-powered aptasensor has the merits of good linear range (1 × 10-11 to 5 × 10-7 M), acceptable limit of detection (1.18 × 10-12 M), and excellent stability and selectivity for STR detection. Additionally, the proposed self-powered aptasensor showed acceptable accuracy for the detection of STR in water. Hopefully, this might stimulate more interest in designing and constructing novel platforms for exquisite photocathodic monitoring of various contaminants in the environment.

Design and optimization of a decoupled serial constant force microgripper for force sensitive objects manipulation

AbstractTo address coupling motion issues and realize large constant force range of microgrippers, we present a serial two-degree-of-freedom compliant constant force microgripper (CCFMG) in this paper. To realize a large output displacement in a compact structure, Scott–Russell displacement amplification mechanisms, bridge-type displacement amplification mechanisms, and lever amplification mechanisms are combined to compensate stroke of piezoelectric actuators. In addition, constant force modules are utilized to achieve a constant force output. We investigated CCFMG’s performances by means of pseudo-rigid body models and finite element analysis. Simulation results show that the proposed CCFMG has a stroke of 781.34 ${\unicode[Times]{x03BC}}\mathrm{m}$ in the X-direction and a stroke of 258.05 ${\unicode[Times]{x03BC}}\mathrm{m}$ in the Y-direction, and the decoupling rates in two directions are 1.1% and 0.9%, respectively. The average output constant force of the clamp is 37.49 N. The amplification ratios of the bridge-type amplifier and the Scott–Russell amplifier are 7.02 and 3, respectively. Through finite element analysis-based optimization, the constant force stroke of CCFMG is increased from the initial 1.6 to 3 mm.

Revealing the contribution of basilar membrane’s biological activity to the mechanism of the cochlear phonosensitive amplification

Revealing the contribution of basilar membrane’s biological activity to the mechanism of the cochlear phonosensitive amplification

Performance enhancement of snap-through vibration energy harvester with displacement amplifier

Vibration energy harvesters (VEH) based on bistable and snap-through mechanisms are being widely employed to harvest energy from different vibration sources. However, under weak ambient excitation, the performance of these systems is marginal. Multi-stability and enhancement techniques, such as displacement amplifier, are being used with bistable VEH to improve its performance. Similar to this, multi-stable snap-through VEH has also been developed; however, the usage of a displacement amplifier in the context of snap-through VEH has not yet been investigated. In this novel study, a displacement amplifier/ displacement amplification mechanism (DAM) is integrated into a snap-through VEH, and the enhanced performance under weak excitation is investigated. A generalized transformation is applied to develop a reduced-order model of the proposed system, and its dynamics and performance under harmonic and random excitation are investigated analytically and numerically. The frequency–amplitude relationship is derived under harmonic excitation, and a detailed investigation of the influence of system parameters on the frequency and force responses is performed. It is observed that by adjusting the mass and stiffness ratio between the VEH and DAM, it is possible to harvest more energy under harmonic excitation of low intensity. In the case of Gaussian white noise excitation, effective potential, and stochastic averaging methods are used to obtain marginal, joint, and stationary probability density functions and mean square power. The influence of noise intensity and other system parameters on the aforementioned measures is thoroughly investigated. It is observed that for specific parameter values, the proposed VEH can harvest 3.3 times more power under harmonic excitation and four times more power under random excitation compared to the snap-through VEH without DAM.

A novel inchworm piezoelectric actuator using two-stage amplification mechanism with high speed: design, modeling, and experimental evaluation

The inchworm piezoelectric actuator has a wide application prospect in the field of precision instruments. However, in view of the complex structure of the existing inchworm piezoelectric actuator and the far distance between the driving feet of the actuator, it is difficult to realize alternate driving and the high output speed of the driving feet, etc. In this paper, an inchworm piezoelectric linear actuator based on two-stage amplification mechanism is designed, which amplifies the output displacement of the driving feet by two-stage amplification mechanism, and improves the driving efficiency of the actuator stator by the way of alternating driving. We present an inchworm piezoelectric actuator with three piezoelectric stacks and a two-stage amplification mechanism, which is simple in structure design, compact in actuator structure and easy to realize alternate driving. The kinematics and dynamics models of the inchworm piezoelectric actuator are established by analyzing the flexible hinge and its structure with the pseudo-rigid body method. The length of the lever structure and the angle of the triangular structure of the piezoelectric actuator are solved by kinematics, and the natural frequency of the whole structure is calculated by dynamics. Through finite element analysis, the simulation magnification ratio of the piezoelectric actuator is obtained, so as to evaluate and verify the theoretical calculation and further optimize the structure. The experimental results show that the inchworm piezoelectric linear actuator using two-stage amplification mechanism has a high driving speed of 5.53 mm s−1 under voltage of 135 V and frequency of 70 Hz.

Theoretical and Experimental Analysis of a Winding Rope Fluid Viscous Damper

This paper investigated a winding rope fluid viscous damper (WRFVD) that uses the frictional amplification mechanism of a winding rope to obtain the operating characteristics of a viscous damper-like device. The WRFVD combined the advantages of fluid viscous dampers and friction dampers. It not only retained the mechanical characteristics of the fluid viscous damper but also reduced manufacturing costs. First, the construction and working principles of the WRFVD were introduced. A theoretical model that could accurately simulate the hysteretic characteristics of the damper was derived. Then, a series of dynamic tests were performed on six prototypes of the WRFVD. The dynamic performance under different displacement amplitudes and device parameters was analyzed based on the test results. In addition, the theoretical model was validated by experimental results. Finally, a series of parametric analyses of the WRFVD were performed. The experimental results showed that the WRFVD is a type of velocity-dependent damper with smooth and plump hysteretic curves under sinusoidal displacement excitation. Fatigue loading tests showed that the WRFVD had excellent fatigue resistance capacity and stable operational performance. The established theoretical model was reasonable and satisfactorily reproduced the hysteretic properties of the WRFVD. The parametric analyses showed that it was not recommended to improve the performance of the WRFVD by the method of adjusting the damping coefficient and pretightening load. It was reasonable to adjust the performance of the WRFVD by setting a smaller velocity exponent, an appropriate winding turn of winding ropes, and a suitable friction coefficient.

Abstract 2153: Cyclin E1 protein overexpression sensitizes ovarian cancer cells to ZN-c3, a novel, selective and oral bioavailable inhibitor of Wee1

Abstract CCNE1 gene amplification is associated with overexpression of Cyclin E1 protein and is an important oncogenic driver. CCNE1 amplification is common in high grade serous ovarian carcinomas (HGSOC) and is associated with platinum resistance and poor patient outcomes. Importantly, Cyclin E1 overexpression can also occur in the absence of gene amplification in ovarian cancer. Overexpression of Cyclin E1 increases CDK2 activity and accelerates entry into S phase of cell cycle, resulting in replication stress and rendering cells more dependent on DNA repair. WEE1 participates in the DNA damage response by controlling essential checkpoints of the cell cycle, preventing cells from entering mitosis and allowing for DNA repair before cell cycle progression. Thus, we hypothesize that ovarian cancers overexpressing Cyclin E1, either via CCNE1 gene amplification or through other independent mechanisms, are more sensitive to WEE1 inhibition. Here, we tested this hypothesis in a range of preclinical cancer models using azenosertib, a novel, selective, and orally bioavailable WEE1 inhibitor currently in clinical development. Ovarian cancer cell lines overexpressing Cyclin E1 protein (Cyclin E1high) were more sensitive to azenosertib than ovarian cancer cell lines with lower levels of Cyclin E1 protein (Cyclin E1low) inducing significant cytotoxic effects (GRmax &amp;lt; -0.5). In Cyclin E1low ovarian cancer cell lines, overexpression of Cyclin E1 increased sensitivity to azenosertib. In contrast, silencing of CDK2 in Cyclin E1high cells reduced sensitivity to azenosertib. In vivo, higher levels of baseline expression of Cyclin E1 in tumor cells were associated with better response to azenosertib, with tumor growth inhibition (TGI) ranging from 51.5% in a Cyclin E1low SKOV3 model to 88% in a Cyclin E1high OVCAR3 model. Azenosertib synergized with chemotherapy agents in multiple ovarian cancer models. In vitro, we report that Cyclin E1high cancer cells were more sensitive to the combination of azenosertib and chemotherapeutics than Cyclin E1low cancer cells. In vivo, the synergy between azenosertib and paclitaxel was stronger in Cyclin E1high OVCAR3 model (46% reduction of initial tumor volume/104% TGI) than Cyclin E1low A2780 model (85% TGI). Taken together, these data suggest that Cyclin E1 overexpression via gene amplification or independent mechanisms sensitize ovarian cancer cells to azenosertib alone or in combination with chemotherapy. This observation supports the use of Cyclin E1 expression to enrich for azenosertib responders in ovarian cancer and possibly other tumor types. Two subsets of Cyclin E1-driven platinum resistant ovarian cancer patients, as defined by gene amplification or protein overexpression, are being enrolled in an azenosertib monotherapy trial. Citation Format: Jianhui Ma, Wen Liu, Heekyung Chung, Hooman Izadi, Petrus DeJong, Olivier Harismendy, Jia li, Fernando Doñate, Ahmed Samatar, Mark Lackner, Laure Escoubet, Kevin Bunker, Daehwan Kim, Nathan Jameson, Tugba Yildiran Ozmen, Kangjin Jeong, Dong Zhang, Wen-An Pan, Gordon Mills. Cyclin E1 protein overexpression sensitizes ovarian cancer cells to ZN-c3, a novel, selective and oral bioavailable inhibitor of Wee1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2153.

Analytic theory of coupled-cavity traveling wave tubes

Coupled-cavity traveling wave tube (CCTWT) is a high power microwave vacuum electronic device used to amplify radio frequency signals. CCTWTs have numerous applications, including radar, radio navigation, space communication, television, radio repeaters, and charged particle accelerators. Microwave-generating interactions in CCTWTs take place mostly in coupled resonant cavities positioned periodically along the electron beam axis. Operational features of a CCTWT, particularly the amplification mechanism, are similar to those of a multicavity klystron. We advance here a Lagrangian field theory of CCTWTs with the space being represented by one-dimensional continuum. The theory integrates into it the space-charge effects, including the so-called debunching (electron-to-electron repulsion). The corresponding Euler–Lagrange field equations are ordinary differential equations with coefficients varying periodically in the space. Utilizing the system periodicity, we develop instrumental features of the Floquet theory, including the monodromy matrix and its Floquet multipliers. We use them to derive closed form expressions for a number of physically significant quantities. Those include, in particular, dispersion relations and the frequency dependent gain foundational to the RF signal amplification. Serpentine (folded, corrugated) traveling wave tubes are very similar to CCTWTs, and our theory applies to them also.

Design and disturbance rejection control of a piezoelectric nanopositioning stage

The article covers structural design and disturbance rejection control of a flexure-based compliant piezoelectric nanopositioning stage. The stage is devised using four-bar amplification mechanisms, auxiliary guiding mechanisms, and a compound parallelogram mechanism. Static and dynamic models of compliant mechanisms are analyzed based on a compliance matrix method. A modified Prandtl-Ishlinskii (PI) model with dead zone operators is used to describe the asymmetric hysteresis. Then, a global electromechanical dynamic model is built and identified. A comprehensive disturbance rejection controller (CDRC) combining a robust H∞ control and a disturbance observer-based (DOB) control is proposed for high trajectory tracking accuracy and anti-disturbance performance. The trajectory tracking accuracy of the stage can be up to 3 nm in experiments. As amplitudes of reference signals increases, relative tracking errors gradually decrease. System instability and oscillation caused by strong external disturbances are also reduced. Experimental results prove the effectiveness of the developed CDRC.

Enhanced solubilization in multi-component mixtures: Mechanism of synergistic amplification of cyclodextrin solubility by urea and inorganic salts

Designed to enhance the solubility of hardly soluble species in water, many excipient formulations for active drugs or other solutes contain two or more cosolutes. And yet, little is known about the mechanism through which excipients act in combination, and how the efficacy of each component toward drug solubility changes compared to when they are acting alone. Here we study aqueous mixtures of urea and inorganic salts and determine their efficacy to solubilize β-cyclodextrin, a cyclic carbohydrate and a key ingredient in many drug formulations. We show that the order in which the salts increased β-cyclodextrin solubility follows the Hofmeister series both in the presence and absence of urea. However, the solubility in many of the urea-salt mixtures is notably higher than the sum of the solubilities in each cosolute on its own, suggesting a synergistic effect between solutes. By determining the activity of urea and NaClO4, the combination showing the strongest synergy, we show that their remarkable solubility enhancement at high concentration is due to a strong urea-assisted accumulation of NaClO4 at the vicinity of β-cyclodextrin. We discuss the molecular interactions that lead to this induced accumulation of NaClO4. Our findings provide new insight into the mechanism of solvation by multiple cosolutes and should aid in the rational design of tailored excipient formulations.