单人Bounce荷载下楼盖结构加速度反应谱设计

Bounce指双脚不离地的人体上下往复运动,是一种常见的有节奏人致激励。采用先进的无线测力鞋垫技术收集了175条bounce荷载曲线,计算每条荷载曲线的单自由系统加速度反应谱,在此基础上提出了设计反应谱分段表达式,主要分为三段：对应bounce一阶主频范围2～3.5 Hz的第一平台段、对应二阶主频范围4～7 Hz的第二平台段以及对应高阶频率的下降段,由试验数据分析给出了两个平台段的不同保证率下的代表值以及下降段参数。文中给出了设计反应谱的详细使用步骤,并通过大跨楼盖试验模型验证了方法的准确性。

单人Bounce荷载的实验建模研究

Bounce指音乐会或体育比赛中常见的观众双脚不离地的身体有节奏的上下往复运动。利用测力板以及无线测力鞋垫,开展了单人在不同频率下的Bounce荷载的测试试验,共得到了109人次822条有效单人Bounce荷载记录。在此基础上,建立了Bounce荷载的傅里叶级数模型,给出了四阶动载因子和相位角的建议值,并与国外已有模型进行了对比分析。本文模型所模拟的Bounce荷载与实测荷载的时域特性相同,所引起的结构响应幅值一致,可供工程设计参考使用。

多人Bounce荷载下结构动力响应折减系数研究

体育比赛、演唱会中观众原地身体上下往复式的欢庆动作会引起Bounce荷载,是典型的有节奏人致动力荷载。该研究将考虑和不考虑人群协同性所计算出的结构响应的比值,定义为Bounce荷载下的结构动力响应折减系数,利用小组人群同步Bounce荷载的实测数据,研究了折减系数随人数、结构频率和阻尼比的变化规律,并提出了对应的设计曲线及表达式。应用于实际结构响应计算时,首先由反应谱法计算单人Bounce荷载下结构的动力响应,将其乘以总体重并考虑振型值影响后,再乘以对应的折减系数,即可实现考虑协同性的人群Bounce荷载下结构动力响应的快速计算,算例分析表明了上述步骤及所建议的折减系数的合理性。

Matter Bounce宇宙模型研究

通过描述宇宙学的发展历史和现状,指出大爆炸理论和暴涨理论虽然有许多优点,可以解释许多现象,但它们并不是完美无缺,无懈可击,仍然有一些无法解释的问题。而matter bounce宇宙模型是一个可以取代前两种理论的模型,可以得到与宇宙观测相吻合的结论,因此研究这个模型是非常有意义的。

Multi-Bounce ATR-FTIR结合Gram-Schmidt正交化法计算烟用香精相似度

采集2种不同风格特征烟用香精的Multi-Bounce Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy(Multi-Bounce ATR-FTIR)指纹图谱,运用主成分分析法各筛选出30条光谱,结合Gram-Schmidt正交化方法,分别建立了2类不同风格特征烟用香精的相似度鉴别模型。使用鉴别模型对未知样品进行相似度计算,并评价使用效果。结果显示,当相似度高于90%时,可以判定属于同一类香精,且相似度越高,风格特征越接近;当相似度低于90%时,可以判定不属于同一类香精,且相似度越低,风格特征的差异越显著。

Observational constraints on the accelerating universe in the framework of a 5D bounce cosmological model

In the framework of a five-dimensional （5D） bounce cosmological model, a useful function f（z） is obtained by giving a concrete expression of deceleration parameter q（z） = q1 ＋q2/1＋1n（1＋z） Then using the obtained Hubble parameter H（z） according to the function f（z）, we constrain the accelerating universe from recent cosmic observations： the 192 ESSENCE SNe Ia and the 9 observational H（z） data. The best fitting values of transition redshift zT and current deceleration parameter q0 are given as zT =0.65-0.12^＋0.25 and q0=-0.76-0.15^＋0.15（1σ）. Furthermore, in the 5D bounce model it can be seen that the evolution of equation of state （EOS） for dark energy Wde can cross over -1 at about z = 0.23 and the current value W0de ： =-1.15 〈 -1. On the other hand, by giving a concrete expression of model-independent EOS of dark energy Wde, in the 5D bounce model we obtain the best fitting values zT = 0 .66-0.08^＋0.11 and q0=-0.69-0.10^＋0.10（1σ） from the recently observed data： the 192 ESSENCE SNe Ia, the observational H（z） data, the 3-year Wilkinson Microwave Anisotropy Probe （WMAP）, the Sloan Digital Sky Survey （SDSS） baryon acoustic peak and the x-ray gas mass fraction in clusters.

Complete Coalescence, Partial Bounce and Rebound: Different Regimes Resulting from the Interaction of a Free Falling Drop with a Target Fluid

The interaction of a falling drop(diluted aqueous solution of ink in various concentrations)with a target fluid(partially degassed tap water)has been tracked by means of high-resolution video recording and photography.The experimental setup has carefully been prepared in order to preserve the axial symmetry of initial conditions.Three regimes of interaction have been identified accordingly(depending on the drop velocity as controlled by the distance of fall):rapid droplet coalescence,rebound with the conservation of the drop volume and shape,and partial coalescence.Previous findings are recovered and confirmed,and enriched with heretofore unseen observations of complex partial coalescence.An extensive set of data is reported to support understanding of the observed dynamics and their repeatability and reproducibility.The overall study has been carried out with the express intent to spur the future development of detailed mathematical models and numerical methods suited for this kind of problems.

Optimization design method of contact bounce and breakaway initial velocity for aerospace electromagnetic relay

Aerospace electromagnetic relay is an electric component that has been widely used in aerospace industry.Contact bounce and contact breakaway for initial velocity are the key parameters that have strong influence on reliability and electric life of the relay.Generally,it is difficult to optimize these two parameters simultaneously.In this paper,according to kinetics theory and structural mechanics,a dynamic reaction calculation model of the relay that describes contact bounce and breakaway for initial velocity is proposed.Under the constraints of contact gap and contact force,the optimal combination of debugging parameters is obtained by the application of orthogonal design.It considers the reduction of contact bounce and the augmentation of breakaway for initial velocity as the optimization objectives,and takes the debugging parameters as the optimization variables.All these above ensure the increase of contact breakaway for initial velocity and the decrease of contact bounce simultaneously,and contact arc erosion is also reduced.

Prostate specific antigen bounce after intensity-modulated radiation therapy in an Asian population

Objective:Serum prostate specific antigen(PSA)is commonly used to evaluate treatment response after definitive radiation therapy(RT).However,PSA levels can temporarily rise without a clear reason,termed“PSA bounce”,and often engender great anxiety for both patients and physicians.The present study aimed to determine the prevalence and factors that predict“PSA bounce”after intensity-modulated radiation therapy(IMRT),and the relevance to biochemical failure and cancer recurrence in an Asian population.Methods:We retrospectively reviewed 206 patients who received IMRT for prostate cancer from 2004 to 2012 in the National Cancer Centre Singapore.These patients were followed up with regular PSA monitoring.We defined“PSA bounce”as a rise of 0.1 ng/mL,followed by two consecutive falls.Patients with biochemical failure(PSA nadir t 2 ng/mL)were further evaluated for cancer recurrence.Results:Sixty-one patients(29.6%)experienced“PSA bounce”,at a median time of 16 months and lasted for 12 months.Age remained the most consistent predictor of the incidence,duration and extent of“PSA bounce”.Other contributory factors included baseline PSA,Gleason score and PSA nadir.Hormonal therapy and prostate volume did not affect this phenomenon.Sixteen patients(7.8%)developed biochemical recurrence,at median time of 32 months,of which 11 were confirmed to have metastatic disease.The median follow-up time was 71 months.

Modified Ceiling Bounce Model for Computing Path Loss and Delay Spread in Indoor Optical Wireless Systems

This paper proposes modifications to the tradional Ceiling Bounce Model and uses it to characterize diffuse indoor optical wireless channel by analyzing the effect of transceiver position on signal propagation properties. The modified approach uses a combination of the tradional ceiling bounce method and a statistical approach. The effects of different transmitter-receiver separations and height of the ceiling on path loss and delay spread are studied in detail.

Cosmology with Bounce by Flat Space-Time Theory of Gravitation and a New Interpretation

General relativity predicts a singularity in the beginning of the universe being called big bang. Recent developments in loop quantum cosmology avoid the singularity and the big bang is replaced by a big bounce. A classical theory of gravitation in flat space-time also avoids the singularity under natural conditions on the density parameters. The universe contracts to a positive minimum and then it expands during all times. It is not symmetric with regard to its minimum implying a finite age measured with proper time of the universe. The space of the universe is flat and the total energy is conserved. Under the assumption that the sum of the density parameters is a little bit bigger than one the universe is very hot in early times. Later on, the cosmological model agrees with the one of general relativity. A new interpretation of a non-expanding universe may be given by virtue of flat space-time theory of gravitation.

Could Gravitons from a Prior Universe Survive a (LQG Inspired) “Quantum Bounce” to Re-Appear in Our Present Universe?

We ask the question if a formula for entropy, as given by with a usual value ascribed of initial entropy of the onset of inflation can allow an order of magnitude resolution of the question of if there could be a survival of a graviton from a prior to the present universe, using typical Planckian peak temperature values of . We obtain values consistent with up to 1038 gravitons contributing to an energy value of if we assume a relic energy contribution based upon each graviton initially exhibiting a frequency spike of 1010 Hz. The value of is picked from looking at the aftermath of what happens if there exists a quantum bounce with a peak density value of [1] in a regime of LQG bounce regime radii of the order of magnitude of meters. The author, in making estimates specifically avoids using ,?by setting the chemical potential for ultra high temperatures for reasons which will be brought up in the conclusion.

Predicting the Curvature of the Cosmos, and Point of Volume Contraction in a Big Bounce Scenario

Based on the latest Planck surveys, the universe is close to being remarkably flat, and yet, within observational error, there is still room for a slight curvature. If the curvature is positive, then this would lead to a closed universe, as well as allow for a big bounce scenario. Working within these assumptions, and using a simple model, we predict that the cosmos may have a positive curvature in the amount, Ω0=1.001802, a value within current observational bounds. For the scaling laws associated with the density parameters in Friedmann’s equations, we will assume a susceptibility model for space, where, , equals the smeared cosmic susceptibility. If we allow the to decrease with increasing cosmic scale parameter, “a”, then we can predict a maximum Hubble volume, with minimum CMB temperature for the voids, before contraction begins, as well as a minimum volume, with maximum CMB temperature, when expansion starts. A specific heat engine model for the cosmos is also entertained for this model of a closed universe.

Gedanken Experiment for Energy, and Scale Factor, Based upon the Assumption of Quintessence and Idea of Quantum Bounce in Order to Isolate Admissible Frequency for Gravitational Waves in the Beginning of Cosmological Evolution

We initially look at a non-singular universe representation of time, and of comparing a general formula of a cosmological Potential energy as given by Padmanbhan, with Weinberg’s Quintessence Potential energy. Isolating a given time component which may serve as an introduction. We then compare this to when , and seeing what the time component then allows as far as available initial energy, the scale factor a(t) and ø, then finally admissible frequency, for Pre Planckian process generated Gravitational waves.

Tensor perturbations from bounce inflation scenario in f(Q)gravity

In this paper,we construct a bounce inflation cosmological scenario in the framework of the modified symmetric teleparallel gravity,namely f(Q)theory,and investigate the tensor perturbations therein.As is well-known,the tensor perturbations generated in the very early Universe(inflation and pre-inflation regions)can account for the primordial gravitational waves(PGWs)that are to be detected by the next generation of GW experiments.We discuss the stability condition of the tensor perturbations in the bounce inflation process and investigate in detail the evolution of the perturbation variable.The general form of the tensor power spectrum is obtained both for large as well as small scale modes.As a result,we show both kinds of modes(short or long wavelength modes),and the tensor spectrum may get a positive tilt in the parametric range where the tensor perturbation proves to be stable—this interestingly hints an enhancement of gravitational waves’amplitude in the background of the f(Q)bounce-inflation scenario.Moreover,we study the LQC-like scenario as a specific case of our model,in which,the primordial tensor power spectrum turns out to be nearly scale-invariant on both small and large scales.

基于计算机视觉的人群Bounce荷载协同性研究

大跨工程结构人致振动问题的日益增多,凸显了人群荷载模型研究的重要性和研究程度的不足.人群内个体间的协同性是人群荷载建模的关键.通过学科交叉,引入计算机视觉技术克服了传统方法所面临的实验成本较高以及同步困难的瓶颈问题.首先介绍光流法及其应用原理,建立了基于光流法的Bounce荷载重构方法并与高精度测力板结果进行对比验证.随后开展基于计算机视觉的人群Bounce实验,重构了多工况下个体的荷载时程,进而定义并计算人群协同性因子,并给出因子随频率及人数的变化规律.结果表明,计算机视觉方法可用于人群Bounce荷载实验测量,并能实现对人群Bounce荷载协同性的定量描述.

Photon motion and weak gravitational lensing in black-bounce spacetime

The effect of spacetime curvature on photon motion may offer an opportunity to propose new tests on gravity theories.In this study,we investigate and focus on the massless(photon)particle motion around blackbounce gravity.We analyze the horizon structure around a gravitational compact object described by black-bounce spacetime.The photon motion and the effect of gravitational weak lensing in vacuum and plasma are discussed,and the shadow radius of the compact object is also studied in black-bounce spacetime.Additionally,the magnification of the image is studied using the deflection angle of light rays.

Quantum ekpyrotic mechanism in Fermi-bounce curvaton cosmology

Within the context of the Fermi-bounce curvaton mechanism,we analyze the one-loop radiative corrections to the four-fermion interaction,generated by the non-dynamical torsion field in the Einstein-Cartan-Holst-Sciama-Kibble theory.We show that contributions that arise from the one-loop radiative corrections modify the energy-momentum tensor,mimicking an effective Ekpyrotic fluid contribution.Therefore,we call this effect quantum Ekpyrotic mechanism.This leads to the dynamical washing out of anisotropic contributions to the energy-momentum tensor,without introducing any new extra Ekpyrotic fluid.We discuss the stability of the bouncing mechanism and derive the renormalization group flow of the dimensional coupling constantξ,checking whether any change of its sign takes place towards the bounce.This enforces the theoretical motivations in favor of the torsion curvaton bounce cosmology as an alternative candidate to the inflation paradigm.

高功率Bounce板条放大器链路热补偿仿真及实验验证

对Bounce抽运结构的高功率板条激光放大器进行热仿真,采用有限元数值分析获得了放大光束通过板条后的光程差分布,利用二阶矩法计算出Bounce抽运热效应引入的相位畸变对光束质量M2的影响,为放大链路热效应的补偿给出指导。在采用高效传导冷却设计的三级板条级联放大链路实验装置中,实验测得的每一放大级热焦距值与理论预期吻合良好。当放大器链路工作在250Hz重复频率时,插入热补偿中继光路,最终获得单脉冲能量537mJ的输出,光束质量因子M2x=2.35,My2=2.66。