Higgs pair production in vector-boson fusion at the LHC and beyond

The production of pairs of Higgs bosons at hadron colliders provides unique information on the Higgs sector and on the mechanism underlying electroweak symmetry breaking (EWSB). Most studies have concentrated on the gluon-fusion production mode which has the largest cross section. However, despite its small production rate, the vector-boson fusion channel can also be relevant since even small modifications of the Higgs couplings to vector bosons induce a striking increase of the cross section as a function of the invariant mass of the Higgs boson pair. In this work we exploit this unique signature to propose a strategy to extract the hhVV quartic coupling and provide model-independent constraints on theories where EWSB is driven by new strong interactions. We take advantage of the higher signal yield of the \(b\bar{b} b\bar{b}\) final state and make extensive use of jet-substructure techniques to reconstruct signal events with a boosted topology, characteristic of large partonic energies, where each Higgs boson decays to a single collimated jet. Our results demonstrate that the hhVV coupling can be measured with 45% (20%) precision at the LHC for \(\mathscr {L}=300\) (3000) fb\(^{-1}\), while a 1% precision can be achieved at a 100 TeV collider.     

Comparison of the iterated equation of motion approach and the density matrix formalism for the quantum Rabi model

The density matrix formalism and the equation of motion approach are two semi-analytical methods that can be used to compute the non-equilibrium dynamics of correlated systems. While for a bilinear Hamiltonian both formalisms yield the exact result, for any non-bilinear Hamiltonian a truncation is necessary. Due to the fact that the commonly used truncation schemes differ for these two methods, the accuracy of the obtained results depends significantly on the chosen approach. In this paper, both formalisms are applied to the quantum Rabi model. This allows us to compare the approximate results and the exact dynamics of the system and enables us to discuss the accuracy of the approximations as well as the advantages and the disadvantages of both methods. It is shown to which extent the results fulfill physical requirements for the observables and which properties of the methods lead to unphysical results.     

Variational multiscale element free Galerkin method for the water wave problems

A new numerical method, which is based on the coupling between variational multiscale method and meshfree methods, is developed for the water wave problems, in which the free surface capturing technique is used to capture the position of the free surface. The proposed method takes full advantage of meshfree methods, therefore, no mesh generation and mesh reconstruction are involved. Meanwhile, due to that the proposed method belongs to meshfree methods, thus it is suitable for the highly deformed free surface flow problems. Finally, two water wave problems are solved and the results have also been analyzed. The numerical results show that the proposed method can indeed obtain accurate numerical results for the water wave problems, which does not refer to the choice of a proper stabilization parameter.     

基于自适应加权窗口的相位质量图提取

加权相位解缠算法的解缠精度取决于所提取的质量图的可靠性。目前提取相位质量图的方法大多采用以各个像素为中心的固定窗口法,但当某些像素被噪声严重干扰时,采用固定窗口法提取质量图往往得不到正确的解缠结果。因此,提出了几种自适应加权窗口方法来提取相位质量图,并给出了具体的实现方法和步骤,同时采用加权小波变换相位解缠算法进行相位解缠。实验结果表明,采用自适应加权窗口方法提取相位质量图来确定初始权重系数能获得比较好的解缠效果。     

基于GSPN的飞机测试性指标确定方法研究

针对现有的图像分割中自适应分割方法的研究难点,以及传统的模糊阈值分割法中存在窗宽不能自动获取的问题,在确定隶属函数的前提下,以图像的直方图为依据,利用分段计算和反变换的方法,提出了一种自适应模糊阈值的图像分割方法,并将该方法应用于机场目标的分割。该方法实现其窗口宽度的自适应选取,并且有效改善了模糊阈值法对直方图呈不明显双峰的图像分割困难的缺点,拓展了模糊阈值图像分割方法的适用范围,改善了模糊阈值分割方法的分割效果。实验结果表明,该方法对直方图呈单峰和多峰分布的的图像有较好的分割效果和效率。     

Application of variational iteration method and homotopy–perturbation method for nonlinear heat diffusion and heat transfer equations

Perturbation methods depend on a small parameter which is difficult to be found for real-life nonlinear problems. To overcome this shortcoming, two new but powerful analytical methods are introduced to solve nonlinear heat transfer problems in this Letter; one is He's variational iteration method (VIM) and the other is the homotopy–perturbation method (HPM). Nonlinear convective–radiative cooling equations are used as examples to illustrate the simple solution procedures. These methods are useful and practical for solving the nonlinear heat diffusion equation, which is associated with variable thermal conductivity condition. Comparison of the results obtained by both methods with exact solutions reveals that both methods are tremendously effective.     

双光子阵列点激发同时多维荧光信息的处理

五维同时荧光信息显微成像方法是一种新的荧光信息获取技术，它采用了双光子阵列点激发方式.这一方法可同时获取激发阵列点每点荧光的位置信息、荧光光谱信息和荧光寿命信息，弥补了现有荧光检测技术的不同功能信息不具有同时性的缺陷.给出了从这种技术的复合信息中提取复合光谱几何强度结构图像、不同光谱几何强度结构图像、不同光谱寿命图像的方法.提出了一种激发荧光强度修正系数矩阵方法，消除阵列点激发光强不均匀对激发荧光强弱产生的不利影响，取得明显效果.实验对实际样品做了数据采集和处理，给出图像结果，表明处理的效果良好.对存在的问题也作了讨论. 关键词： 荧光信息处理 双光子 荧光光谱 荧光寿命     

Methods for Thickness Determination of SiC Homoepilayers by Using Infrared Reflectance Spectroscopy

Infrared reflectance spectra have been widely used to measure layer thickness based either on calculation or on curve fitting, and two traditional methods for thickness determination have been studied. Considering the disadvantages of those two methods, we propose a new fitting model based on the fitting of the fringe order difference. In comparison with the measured results, the new fitting model shows its superiority not only for its stable and accurate results which have great agreement with the results from SEM, but also for its simple and quick fitting process.     

Geodesic connectedness of stationary spacetimes with optimal growth

In the last fifteen years variational methods have been widely applied in the study of geodesic connectedness of stationary spacetimes. In this paper we introduce fine estimates which allow us to apply such methods to this problem in an optimal way, improving by far previous results on the subject. Our estimates also seem useful for extending the existing results in other related subjects, for example, connectedness by timelike geodesics and existence of normal trajectories.     

Theoretical and experimental aspects of chaos control by time-delayed feedback

We review recent developments for the control of chaos by time-delayed feedback methods. While such methods are easily applied even in quite complex experimental context the theoretical analysis yields infinite-dimensional differential-difference systems which are hard to tackle. The essential ideas for a general theoretical approach are sketched and the results are compared to electronic circuits and to high power ferromagnetic resonance experiments. Our results show that the control performance can be understood on the basis of experimentally accessible quantities without resort to any model for the internal dynamics.     

高分辨显微镜纳米云纹方法的发展与应用

介绍了近年来发展的纳米云纹法及其新的应用。这些方法是基于原子力显微镜、扫描隧道显微镜和透射电子显微镜的原理提出来的。纳米云纹法能够对物体的微/纳观变形提供定量的分析。详述了这些方法的测量原理和实验技术,并进行了新的应用研究。实验结果论证了这些方法的可行性,并证实了这些方法具有纳米级的位移测量灵敏度。     

D-u关系的最小绝对值线性拟合法

 采用最小绝对值方法对几类物质的冲击波速度D与波后粒子速度u的关系进行了直线拟合,并将其与常用的最小二乘法拟合的结果进行了比较。结果显示：对于实验数据分散性较小的密实材料（金属、离子晶体、氧化物等）,两种方法拟合的线性系数一致;而对于实验数据分散性较大的一些疏松材料（包括液体等）,两种方法拟合的线性系数有差异。对所有物质,最小绝对值法拟合的平均绝对误差比最小二乘法拟合的要小,因而最小绝对值法较最小二乘法有更高的准确性。同时讨论了导致这两种拟合差异的因素。     

基于多种小波分解方法综合判决的低误报率分布式光纤围栏入侵监测系统

针对相位敏感光时域反射计型分布式光纤围栏入侵监测系统对外界干扰敏感、误报率高的问题进行了深入研究,比较了多种小波提取入侵信号突变特征方法,并提出一种基于多个小波分解结果进行综合判决来降低分布式光纤围栏误报率的方法.实验结果表明,多种小波分解可以分别提取不同层次的突变细节信息,为综合决策提供更完备的信息和条件,比单一判决能更有效降低系统误报率,室外长期测试可达到0-1次/24h,大大提高了分布式光纤围栏报警系统的稳定性和置信度水平.     

Characterization of ultrasonic transducers using cholesteric liquid crystals

This paper relates to two methods for the characterization of ultrasonic transducers by means of a visualization technique which exploits the thermotropic properties of cholesteric liquid crystals. Examples illustrating these methods are used to demonstrate the validity of the results obtained whilst maintaining the advantages of a simple and economic technique.     

激光功率对光镊光阱刚度标定的影响

光阱刚度是描述光镊对粒子进行操控的重要力学指标,实际使用过程中会受到激光功率的影响。采用均方位移法及玻尔兹曼统计法对搭建的光镊系统进行光阱刚度的标定,利用图像采集方法进行微粒位移的测量,并对两种方法的测量结果进行了比较。为了提高光阱刚度的标定结果的准确性,分析了光路放大倍数、温度变化对最后标定结果的精度影响。结果表明,两种方法进行标定的结果基本相同;光阱刚度在低激光功率（1 mW ~20 mW）范围时随功率近似线性增加,在高功率情况下（25 mW~60 mW）随功率增加不再线性增加,而是趋于一个饱和值。此外,光路放大倍数标定的精确性对标定的精度影响较大,10%的相对误差时,标定结果产生23%的变化,温度对标定的精度影响较小,0.1 ℃的温度变化导致标定结果0.034%的变化。     

Noninvasive measurement of scattering anisotropy in turbid materials by nonnormal incident illumination

Many existing methods for the recovery of optical parameters from turbid materials rely on the diffusion approximation, which does not permit the recovery of the degree of anisotropy in the scattering phase function. These methods also make the explicit assumption that light is normally incident at the top surface of the material. We demonstrate a steady-state imaging technique that uses nonnormally incident light to determine anisotropy parameter g by fitting Monte Carlo simulation results to high dynamic range images of the intensity profiles of samples. The proposed method is simpler than existing methods and does not rely on thin samples to produce reasonable results.     

A Bootstrap Framework for Aggregating within and between Feature Selection Methods

In the past decade, big data has become increasingly prevalent in a large number of applications. As a result, datasets suffering from noise and redundancy issues have necessitated the use of feature selection across multiple domains. However, a common concern in feature selection is that different approaches can give very different results when applied to similar datasets. Aggregating the results of different selection methods helps to resolve this concern and control the diversity of selected feature subsets. In this work, we implemented a general framework for the ensemble of multiple feature selection methods. Based on diversified datasets generated from the original set of observations, we aggregated the importance scores generated by multiple feature selection techniques using two methods: the Within Aggregation Method (WAM), which refers to aggregating importance scores within a single feature selection; and the Between Aggregation Method (BAM), which refers to aggregating importance scores between multiple feature selection methods. We applied the proposed framework on 13 real datasets with diverse performances and characteristics. The experimental evaluation showed that WAM provides an effective tool for determining the best feature selection method for a given dataset. WAM has also shown greater stability than BAM in terms of identifying important features. The computational demands of the two methods appeared to be comparable. The results of this work suggest that by applying both WAM and BAM, practitioners can gain a deeper understanding of the feature selection process.     

Investigation of laser scribing of a-Si:H from the film side for solar modules using a UV laser with ns pulses

This paper investigates laser scribing of a-Si:H layers from the film side with a ns pulsed UV laser for thin-film solar modules. We compared the contact resistance for several scribing methods and find that a low contact resistance is only achieved for double scribing methods (i.e. scribing the same line twice). Furthermore, we find that for such double scribing methods the alignment between the laser spots of the first and second sub-scribes is critical for good-quality contacts. In order to analyze these results in more detail, we examined the morphology and chemical composition at the surface of the laser lines using scanning electron microscopy, X-ray photoelectron spectroscopy and secondary ion mass spectrometry. From this analysis, we conclude that a good alignment between the first and second scribes results in less re-deposition of silicon in the form of SiO₂ on the surface, which explains differences in contact resistance found for the various scribing methods. As a good alignment between the two sub-scribes is difficult to obtain, these double scribing methods are not attractive for industrial application. We developed a new scribing method for which alignment between the two scribes is not critical, and demonstrate that we can obtain high-quality contacts with this method.     

Infrared radiation from non-homogeneous gas mixtures having overlapping bands

Existing methods for treating nonhomogeneous gas radiation are extended to include radiation from non-homogeneous mixtures of gases which have overlapping absorption-emission bands. Narrow band and wide band methods are discussed. A simplified wide band method is presented whereby hand calculations of the intensity emitted by such gas mixtures can be performed. Calculations are made by the narrow and wide band methods and the results compared.     

A theoretical introduction to the development of a unified approach to flexible rotor balancing

Several successful methods for balancing flexible rotating shafts have been developed in recent years, whose relative merits have been the subject of much debate and argument. These methods can be separated into two, seemingly distinct, groups which can be concisely identified as modal balancing and influence coefficient techniques. The present authors consider that in practice many of the differences are more apparent rather than real and that the time has arrived for an attempt to reconcile the differences and hopefully to synthesize a method which includes the best features of both methods. This paper reviews the theoretical basis for this programme. The results of a preliminary experimental exploration have been recorded elsewhere.