The Equilibrium Range of Wind Wave Spectra: an Explanation Based on White Noise

Laboratory experiments and field observations show that the equilibrium range of wind wave spectra presents a – 4 power law when it is scaled properly. This feature has been attributed to energy balance in spectral space by many researchers. In this paper we point out that white noise on an oscillation system can also lead to a similar inverse power law in the corresponding displacement spectrum, implying that the – 4 power law for the equilibrium range of wind wave spectra may probably only reflect the randomicity of the wind waves rather than any other dynamical processes in physical space. This explanation may shed light on the mechanism of other physical processes with spectra also showing an inverse power law, such as isotropic turbulence, internal waves, etc.

The double helium-white dwarf channel for the formation of AM CVn binaries

Most close double helium white dwarfs will merge within a Hubble time due to orbital decay by gravitational wave radiation.However,a significant fraction with low mass ratios will survive for a long time as a consequence of stable mass transfer.Such stable mass transfer between two helium white dwarfs（He WDs） provides one channel for the production of AM CVn binary stars.In previous calculations of double He WD progenitors,the accreting He WD was treated as a point mass.We have computed the evolution of 16 double He WD models in order to investigate the consequences of treating the evolution of both components in detail.We find that the boundary between binaries having stable and unstable mass transfer is slightly modified by this approach.By comparing with observed periods and mass ratios,we redetermine masses of eight known AM CVn stars by our double He WDs channel,i.e.HM Cnc,AM CVn,V406 Hya,J0926,J1240,GP Com,Gaia14 aae and V396 Hya.We propose that central spikes in the triple-peaked emission spectra of J1240,GP Com and V396 Hya and the surface abundance ratios of N/C/O in GP Com can be explained by the stable double He WD channel.The mass estimates derived from our calculations are used to discuss the predicted gravitational wave signal in the context of the Laser Interferometer Space Antenna（LISA） project.

Selection of Reference Genes in Equine White Blood Cells for Real Time PCR Normalization Following Extracorporeal Shock Wave Therapy

Selection of proper reference genes (RGs) is an essential step needed for accurate normalization of results from genomic studies. Expression of RGs is regulated by many factors such as species, age, gender, type of tissue, the presence of disease, and the administration of therapeutic treatment. The aim of the present study was to identify optimal RGs in a set of blood samples collected at different time points (0, 24, 48, 72 h) from horses following administration of extracorporeal shock wave therapy (ESWT). The mRNA expression of twelve RGs: HPRT1, ACTB, HSP90A, SDHA, GUSB, B2M, UBC, NONO, TBP, H6PD, RPL32, GAPDH was determined using real time quantitative polymerase chain reaction (qPCR). An SAS program developed on the algorithm of geNorm, SASqPCR, was used to determine stability of the expression and the number of optimal RGs. The results showed that the range of quantification cycle (Cq) values of the evaluated genes varied between 17 and 26 cycles, and that one optimal RG, ACTB, was sufficient for normalization of gene expression. Results of stability of expression demonstrated that ACTB was the optimal choice for all the samples studied. Notably, in samples collected at 72 h post ESWT, TBP showed a significant change in the expression level, and was not suitable for use as a RG. These results substantiate the importance of validating and selecting an appropriate RG.

Resistance of Major Rice Cultivars in Hangzhou Area of China against Southern Rice Black-streaked Dwarf Virus

Resistance of 17 major rice cultivars in Hangzhou region of China against southern rice black-streaked dwarf virus was tested in the paper. The results showed that the incidence rate of southern rice black-streWed dwarf virus had certain positive correlation with quantity of white-backed planthopper （Sogatellafurci-fera） and resistance among various cultivars was significant. Two varieties, Yueyou 9113 and Tianyouhuazhan, were most susceptible ; Yongyou 8, Jiayou 2 and Xi-ushui 134 had best resistance and could be used as disease-resistant varieties to prevent the disease.

An Implementation of Galactic White Dwarf Binary Data Analysis for MLDC-3.1

The space-borne gravitational wave detectors will observe a large population of double white dwarf binaries in the Milky Way.However,the search for double white dwarfs in the gravitational wave data will be time-consuming due to the large number of templates involved and antenna response calculation.In this paper,we implement an iterative combinatorial algorithm to search for double white dwarfs in MLDC-3.1 data.To quickly determine the rough parameters of the target sources,the following algorithms are adopted in a coarse search process:(1)using the downsampling method to reduce the number of original data points;(2)using the undersampling method to speed up the generation of a single waveform template;(3)using the stochastic template bank method to quickly construct the waveform template bank while achieving high coverage of the parameter space;(4)combining the FFT acceleration algorithm with the stochastic template bank to reduce the calculation time of a single template.A fine search process is applied to further determine the parameters of the signals based on the coarse search,for which we adopt the particle swarm optimization.Finally,we detect O(10^(4))double white dwarf signals,validating the feasibility of our method.

The gravitational wave emission of double white dwarf coalescences

Type Ia Supernovae(SNe Ia)are widely used as standard candles to probe the Universe.However,how these fierce explosions are produced itself is still a highly debated issue.There are mainly two popular models for SNe Ia:the double-degenerate scenario and the single-degenerate scenario.The doubledegenerate scenario suggests that SNe Ia are produced by the coalescence of two degenerate white dwarfs,while the single-degenerate scenario suggests that the continuous accretion of a single degenerate white dwarf from its normal stellar companion will finally lead to a disastrous explosion when it is over-massive,resulting in an SN Ia.The rapid development of the gravitational wave astronomy sheds new light on the nature of SNe Ia.In this study,we calculate the gravitational wave emissions of double white dwarf coalescences and compare them with the sensitivities of several upcoming detectors.It is found that the gravitational wave emissions from double white dwarf mergers in the local universe are strong enough to be detected by LISA.We argue that LISA-like gravitational wave detectors sensitive in the frequency range of 0.01—0.1 Hz will be a powerful tool to test the double-degenerate model of SNe Ia,and also to probe the Universe.

Ecological Fitness of Non-vector Planthopper Sogatella furcifera on Rice Plants Infected with Rice Black Streaked Dwarf Virus

We evaluated the effects of rice black streak dwarf virus （RBSDV）-infested rice plants on the ecological parameters and its relevant defensive and detoxification enzymes of white-backed planthopper （WBPH） in laboratory for exploring the relationship between RBSDV and the non-vector planthopper. The results showed that nymph survival rate, female adult weight and fecundity, and egg hatchability of WBPH fed on RBSDV-infested rice plants did not markedly differ from those on healthy plants, whereas the female adult longevity and egg duration significantly shortened on diseased plants. Furthermore, significantly higher activities of defensive enzymes （dismutase, catalase and peroxidase） and detoxification enzymes （acetylcholinesterase, carboxylesterase and glutathione S-transferase） were found in WBPH adults fed on infected plants. Results implied that infestation by RBSDV increased the ecological fitness of non-vector planthopper population.

Revealing Double White Dwarf Mergers with Multi-messenger Signals

A significant number of double white dwarfs(DWDs)are believed to merge within the Hubble time due to the gravitational wave(GW)emission during their inspiraling phase.The outcome of a DWD system is either a type Ia Supernova as the double-degenerate model,or a massive,long-lasting merger remnant.Expected multi-messenger signals of these events will help us to distinguish detailed merging physical processes.In this work,we aim to provide a generic scenario of DWD merging,investigate the emission of all major messengers,with a focus on GWs and neutrinos.Our goal is to provide some guidance for current and future(collaborative)efforts of multimessenger observations.Throughout the merging evolution of a DWD system,different messengers(GW,neutrino and electromagnetic wave)will dominate at different times.In this work,we show that DWD merger events located at the distance of 1 kpc can indeed produce detectable signals of GWs and neutrinos.The GW frequency is in 0.3–0.6 Hz band around 10 days before tidal disruption begins.We estimate that in optimistic situations,the neutrino number detected by upcoming detectors such as JUNO and Hyper-Kamiokande can reach O(1)for a DWD merging event at~1 kpc.

基于改进Xu-White模型的富有机质页岩横波预测方法研究

横波速度是储层表征描述、AVO分析和流体识别的重要信息。干酪根是富有机质页岩的重要成分且具有非固体非流体的特殊弹性性质,常规处理方法是将其等效为流体。这里提出了一种基于变化孔隙纵横比Xu-White模型的富有机质页岩横波预测方法,首先将干酪根同时等效为基质矿物和孔隙流体引入模型中,然后利用模拟退火粒子群算法,在约束条件下,反演出变化孔隙纵横比,并以变化孔隙纵横比初始化,模型构建富有机质变化孔隙纵横比Xu-White模型,最后结合测井信息与岩石物理模型预测横波速度。将该方法应用于中国西南部四川盆地东南焦石坝地区某井位,通过对比固定孔隙纵横比Xu-White模型方法与干酪根流体等效的变化孔隙纵横比Xu-White模型预测结果,验证了该方法的适用性和准确性。本方法将为富有机质页岩的研究提供更准确的横波速度资料。

3种典型炸药水中爆炸初始冲击波的近场参数测试

为了探索水中爆炸初始冲击波近场的传播特性和衰减差异,扩展水箱法测爆压试验的研究范围,采用高速摄影狭缝扫描测试方法,对3种典型的柱状炸药(TNT、JH-14、JO-9159)水中爆炸过程进行了测试研究,测量获得了一维正平面水中初始冲击波传播的时间历程演化曲线;由此拟合计算出柱状炸药的水中初始冲击波传播速度随时间的变化曲线,进一步由水的冲击雨果尼奥方程和冲击波动量方程、界面上压力和质点速度连续的条件及声学近似理论,计算得到了水中爆炸初始冲击波阵面压力的衰减曲线和炸药试样的爆压、多方指数等爆轰参数。结果表明,水中爆炸初始冲击波阵面压力近似以指数形式衰减,初始阶段衰减极快;当炸药爆压为20~37 GPa时,水中冲击波初始速度处于5.66~6.81 km/s的范围,波阵面初始压力与炸药的爆压近似成线性关系;虽然JO-9159的爆速和爆压均高于JH-14和TNT,但其水中初始冲击波传播仅在7μs后,其冲击波速度与波阵面压力下降至最低,说明以HMX为基的理想炸药水中爆炸初始冲击波速度和波阵面压力的衰减率要高于以RDX为基的理想炸药和TNT,高爆速、高爆压类理想炸药在水中初始冲击波性能方面优势不显著。

高速平板边界层中定常条带的前缘感受性

来流湍流度较高时,自由流涡波可在边界层内激发流向条带结构,并引起边界层的旁路(bypass)转捩。本文采用调和线性化Navier-Stokes方程(harmonic linearized Navier-Stokes,HLNS)方法模拟平板边界层条带对自由流涡波的前缘感受性,并通过直接数值模拟验证了HLNS方法的可靠性。针对马赫数4.8的高速平板边界层,分析了零频涡波激发定常条带的前缘感受性过程及定常条带的演化规律。研究结果表明,边界层外的自由流涡扰动对边界层条带的发展存在持续的激励作用;对于固定展向波数的自由流涡波,法向波数为0时激发的条带幅值最大;自由流涡波的法向波数在小于临界角度时仅影响条带的幅值,而不影响条带扰动的形函数剖面。随着当地雷诺数的增加,条带的幅值演化和形函数剖面呈现出很好的相似性;当地无量纲展向波数β=0.18时,归一化幅值最大。

基于Xu-White模型横波速度预测的误差分析

在砂泥岩剖面中,基于Gassmann方程和Xu-White岩石物理模型,利用常规测井资料及实验室岩石物理数据进行横波速度估算.模型中考虑了泥质砂岩中基质性质、泥质含量、孔隙度大小和孔隙形状以及孔隙饱含流体性质对岩石速度的影响.综合分析了模型中砂、泥岩和孔隙流体弹性参数以及孔隙纵横比等输入参数的误差对预测横波速度精度的影响.数值模型试验表明,在Xu-White模型中采用变化的孔隙纵横比估算出的横波速度远远比采用固定孔隙纵横比估算出的横波速度准确.

虚拟孔隙度优化Xu-White模型法预测横波速度

纵、横波速度和密度是连接岩石各种物理性质与地震波勘探的桥梁,是储层岩性、物性和流体分析识别的重要参数。在实际工作中只有极少数井进行了横波速度测井,甚至没有横波资料,而利用横波速度可以得到泊松比、拉梅模量等反映流体性质的物理量,减少地震振幅解释的多解性,这种情况下,就需要预测横波速度。文中在Xu-White理论模型的基础上,通过引入虚拟孔隙度和误差融合技术,优化了预测横波速度过程,减少了孔隙的扁度和骨架参数带来的误差,并在预测过程中增加了质量控制手段,提高了横波预测的精度。在肇源南和敖南地区的横波速度预测工作中,预测结果与实测横波吻合程度较高,说明该方法在实际应用中能够取得较好的效果。

Xu-White模型预测横波速度的不确定因素分析

自Xu和White(1995)建立了泥质砂岩的有效介质模型(Xu-White模型)后,很多地球物理学者用此模型或改进的模型进行岩石横波速度的预测,但至今很少有人对Xu-White模型预测过程中的不确定因素进行详细总结。介绍了Xu-White模型及其预测流程;对预测过程中的不确定因素进行了分析,指出在使用中可以根据实际地质情况合理的取舍参数,从而能更有效地进行纵横波速度预测。

基于Xu-White模型TZ地区致密砂岩弹性波速测井解释

深层致密砂岩储层是TZ地区油气勘探、开发的重点,纵横波弹性波速精细解释对地震、测井及钻完井施工均具有重要意义。由于该地区大部分井缺少密度及横波测井资料,而这些资料往往是弹性波速反演或进行预测效果验证所必须的。本文首先利用常规中子、泥质等测井资料对声阻抗进行反演,对各井岩石密度进行精细解释。利用基质矿物模量自提取方法及Xu-White模型对致密砂岩基质矿物体积模量及剪切模量、干岩样体积模量及剪切模量进行表征,最后利用Gassman方程对岩石纵横波波速进行预测。结果表明,AC与自适应提取的基质矿物各模量间存在较好的二次多项式相关性,因此可以利用AC对基质矿物各模量进行定量表征,从而简化自适应提取方法,提高计算效率;利用该方法预测的纵波及横波波速平均相对误差分别小于0.8%和2%,明显好于常规经验法,因而对于该地区深层致密砂岩储层地质结构精细解释具有参考价值。

利用Xu-White模型估算地震波速度

在测井资料中,通常缺乏横波测井资料,这为地震波正演模拟和地震反演都带来一定的困难。基于Xu White模型,作者利用常规测井资料AC,RT和GR曲线,以及实验室岩石物理数据进行地震波速度估算,有机地结合了Gassmann方程和Kuster Toks z模型,并充分考虑到了泥质砂岩中岩石基质性质、泥质含量、孔隙度大小和形状及孔隙饱含流体性质对岩石速度的影响。然而,由于存在“数据测量”和“模型估算”的不精确性,输入参量和输出结果都不可能完全的精确,为此在利用Xu White模型的同时引入信息合取反演算法,建立一个联系所有输入参数和输出结果之间的后验概率密度函数,通过寻找模型空间的最大似然点达到最优化模型结果的目的。该反演方法应用于吉林新立油田测井资料分析,纵波速度和密度估算结果在可接受的误差范围内,能够对由于井壁垮塌造成的密度测量偏差进行校正,为横波估算结果的利用提供了合理性保证。

基于Xu-White模型横波速度预测的误差分析

在砂泥岩剖面中,基于Gassmann方程和Xu-White岩石物理模型,利用常规测井资料及实验室岩石物理数据进行横波速度估算。模型中考虑了泥质砂岩中基质性质、泥质含量、孔隙度大小和孔隙形状以及孔隙饱含流体性质对岩石速度的影响。综合分析了模型中沙、泥岩和孔隙流体弹性参数以及孔隙纵横比等输入参数的误差对预测横波速度精度的影响。数值模型试验表明,在Xu-White模型中采用变化的孔隙纵横比估算出的横波速度远远比采用固定孔隙纵横比估算出的横波速度准确。

采用Xu-White模型进行横波预测影响因素分析

砂泥岩的Xu-White模型常被用于横波预测,该模型综合考虑了砂泥岩中的泥质含量、孔隙度及孔隙形状、孔隙饱含流体的性质等对岩石速度的影响。为了深入了解泥质含量、含水饱和度、砂岩孔隙纵横比对Xu-White模型横波预测影响因子的大小,建立了三个气水模型进行试验并分析。结果表明:误差影响权重由高到低依次为泥质含量、砂岩孔隙纵横比、含水饱和度。运用综合考虑三个误差因素的改进Xu-White模型进行横波预测的结果与实测资料吻合性良好。

基于ACBO-GM联合方法的高维变量结构模型修正

工程结构模型修正常面临变量维度高、非线性程度强等现实问题,其模型修正的精度和效率受到严重影响,为改善这一不足,提出基于改进物体碰撞算法(Advanced Colliding Bodies Optimization,ACBO)和高斯白噪声扰动(Gaussian-white-noise Mutation,GM)的联合修正方法。在联合方法中,ACBO实现从传统的“一对一”到“优对多”的碰撞模式的转变,GM则用于保证碰撞过程中种群的多样性,可有效提升结构模型修正效率。基于一系列测试函数,对比分析标准物体碰撞算法(Colliding Bodies Optimization,CBO)和联合优化方法的优化性能;给出基于ACBO-GM联合方法的修正流程,并将其应用于钢框架修正算例和悬臂梁修正实例,对比研究基于联合修正方法与基于遗传算法(Genetic Algorithm,GA)的修正精度和效率。研究表明,ACBO-GM联合优化方法在精度和效率方面都明显优于传统的CBO方法,该优化方法的可行性得到验证;基于ACBO-GM联合方法在钢框架和悬臂梁两个工程结构修正案例中的应用,其修正精度均与基于GA方法的精度一致,但修正效率显著优于基于GA的修正方法。

非高斯波浪作用下深水高墩的非线性随机振动

首先,建立非高斯波浪作用下深水高墩的随机动力学模型,采用泊松白噪声激励模拟非高斯随机波浪过程,利用达朗贝尔原理和伽辽金方法推导深水高墩的运动方程。然后,通过径向基神经网络法求解广义FPK方程,获得系统的瞬态响应概率密度函数。最后,考察不同结构参数对系统响应的影响,并采用蒙特卡罗模拟(MCS)验证理论解。结果表明:理论解与模拟结果吻合良好;浸入比和质量比增加均会放大高墩的响应;采用高斯模型会使结构设计偏于保守。