FeW的差分故障攻击

为了评估轻量级分组密码算法FeW的安全性,提出并讨论了一种针对FeW算法的差分故障攻击方法。该方法采用单字节随机故障模型,选择在FeW算法的最后一轮右侧引入单字节随机故障,利用线性扩散函数的特点获取差分信息,并基于S盒差分分布统计规律实现密钥恢复。实验结果表明,平均47.73次和79.55次故障注入可以分别完全恢复FeW-64-80和FeW-64-128的主密钥,若在恢复密钥过程中加入210的穷举计算,所需平均故障注入次数分别降至24.90和41.50。该方法可以有效地攻击FeW算法。

Supercapacitor electrode based on few-layer h-BNNSs/rGO composite for wide-temperature-range operation with robust stable cycling performance

Currently,developing supercapacitors with robust cycle stability and suitability for wide-temperature-range operations is still a huge challenge.In the present work,few-layer hexagonal boron nitride nanosheets(h-BNNSs)with a thickness of 2−4 atomic layers were fabricated via vacuum freeze-drying and nitridation.Then,the h-BNNSs/reduced graphene oxide(rGO)composite were further prepared using a hydrothermal method.Due to the combination of two two-dimensional(2D)van der Waals-bonded materials,the as-prepared h-BNNSs/rGO electrode exhibited robustness to wide-temperature-range operations from−10 to 50℃.When the electrodes worked in a neutral aqueous electrolyte(1 M Na2SO4),they showed a great stable cycling performance with almost 107%reservation of the initial capacitance at 0℃ and 111% at 50℃ for 5000 charge−discharge cycles.

Image reconstruction from few views by l_0-norm optimization

In the medical computer tomography （CT） field, total variation （TV）, which is the l1-norm of the discrete gradient transform （DGT）, is widely used as regularization based on the compressive sensing （CS） theory. To overcome the TV model＇s disadvantageous tendency of uniformly penalizing the image gradient and over smoothing the low-contrast structures, an iterative algorithm based on the l0-norm optimization of the DGT is proposed. In order to rise to the challenges introduced by the l0-norm DGT, the algorithm uses a pseudo-inverse transform of DGT and adapts an iterative hard thresholding （IHT） algorithm, whose convergence and effective efficiency have been theoretically proven. The simulation demonstrates our conclusions and indicates that the algorithm proposed in this paper can obviously improve the reconstruction quality.

Synthesized few-layers hexagonal boron nitride nanosheets

The hexagonal boron nitrides （BNs） with different morphologies are synthesized on a large scale by a simple route using a two-step synthetic process. The morphology of h-BN can be easily controlled by changing the heat-treatment atmosphere. The whiskers with 0.5-10 μm in diameter and 50-100 μm in length consist of few-layers nanosheets in the NH3 gas. The BN nanosheets can be dissociated from the whiskers by ultrasonic treatment, which are less than 5 nm in thickness and even only two layers thick. The concentration and activity of N play an important rule, and abundant N and higher activity are conducive for refining grain in reaction. The H3BO3 and C3N6H6 molecules form a layer-like morphology with the interlinked planar triangle by a hydrogen-bonded structure.

Few算子和多项式时间概率算法PP的能力

本文提出Ｆｅｗ算子并研究其决定的复杂性类，得到了复杂性类ＰｔｔＣ的新刻划．利用此刻划讨论了多项式时间概率复杂性类ＰＰ的能力．

Electron acceleration by tightly focused radially polarized few-cycle laser pulses

Within the framework of plane-wave angular spectrum analysis of the electromagnetic field structure, a solution valid for tightly focused radially polarized few-cycle laser pulses propagating in vacuum is presented. The resulting field distribution is significantly different from that based on the paraxial approximation for pulses with either small or large beam diameters. We compare the electron accelerations obtained with the two solutions and find that the energy gain obtained with our new solution is usually much larger than that with the paraxial approximation solution.

Few-layered graphene via gas-driven exfoliation for enhanced supercapacitive performance

High-quality graphene flakes have long been desirable for numerous applications including energy stor- age, printable electronics, and catalysis. In this contribution, we report a green, efficient, facile gas-driven exfoliation process for the preparation of high-quality graphene in large scale. The gas exfoliation process was realized by the interplay between the expansion of interlayer at high temperature and the gasifi- cation of liquid nitrogen within the interlayer. Detailed experiments demonstrated that the higher tem- perature was critical to the formation of fewer layers. The exfoliated graphene was proved to be of high quality. We further investigated the electrochemical behavior of this exfoliated graphene. As a result, this few-layered graphene demonstrated an enhanced capability as a supercapacitor, much higher than its counterpart parent material.

Moir patterns and step edges on few-layer graphene grown on nickel films

Few-layer graphene grown on Ni thin films has been studied by scanning tunneling microscopy. In most areas on the surfaces, moir6 patterns resulted from rotational stacking faults were observed. At a bias lower than 200 mV, only one sublattice shows up in regions without moir6 patterns while both sublattices are seen in regions with moir6 pattens. This phenomenon can be used to identify AB stacked regions. The scattering characteristics at various types of step edges are different from those of monolayer graphene edges, either armchair or zigzag.

Accurate determination of the absolute phase and temporal-pulse phase of few-cycle laser pulses

A Fourier analysis method is used to accurately determine not only the absolute phase but also the tempuralpulse phase of an isolated few-cycle （chirped） laser pulse. This method is independent of the pulse shape and can fully characterize the light wave even though only a few samples per optical cycle are available. It pavas the way for investigating the absolute phase-dependent extreme nonlinear optics, and the evolutions of the absolute phase and the temporal-pulse phase of few-cycle laser pulses.

Intensity-dependent asymmetric photoionization in few-cycle laser pulses

The asymmetric photoionization of atoms irradiated by intense, few-cycle laser pulses is studied numerically. The results show that the pulse intensity affects the asymmetric photoionization in three aspects. First, at higher intensities, the asymmetry becomes distinctive for few-cycle pulses of longer durations. Second, as the laser intensity increases, the maximal asymmetry first decreases then increases after it has reached a minimal value. Last, the value of the carrier-envelope phase corresponding to the maximal asymmetry varies with the pulse intensity. This study reveals that the increasing of pulse intensity is helpful for observing the asymmetric photoionization.

Modeling of Few-Mode Multi-Core Optical Fiber Channel Based on Non-Uniform Mode Field Distribution

In this paper, the influencing factors that affect few-mode and multi core optical fiber channel are analyzed in a comprehensive way. The theoretical modeling and computer simulation of the information channel are carried out and then the modeling scheme of few-mode multicore optical fiber channel based on non-uniform mode field distribution is put forward. The proposed modeling scheme can not only exponentially increases the system capacity through fewmode multi-core optical fiber channel, but has better transmission performance compared to the channel of the same type to the uniform channel revealing from the simulation results.

Boltzmann or Gibbs Entropy? <br/>Thermostatistics of Two Models with Few Particles

We study the statistical mechanics of small clusters (N ~ 10 - 100) for two-level systems and harmonic oscillators. Both Boltzmann’s and Gibbs’s definitions of entropy are used. The properties of the studied systems are evaluated numerically but exactly;this means that Stirling’s approximation was not used in the calculation and that the discrete nature of energy was taken into account. Results show that, for the two-level system, using Gibbs entropy prevents temperatures from assuming negative values;however, they reach very high values that are not plausible in physical terms. In the case of harmonic oscillators, there are no significant differences when using either definition of entropy. Both systems show that for N = 100 the exact results evaluated with statistical mechanics coincide with those found in the thermodynamic limit. This suggests that thermodynamics can be applied to systems as small as these.

Generation of few-cycle laser pulses:Comparison between atomic and molecular gases in a hollow-core fiber

We numerically study the pulse compression approaches based on atomic or molecular gases in a hollow-core fiber.From the perspective of self-phase modulation（SPM）, we give the extensive study of the SPM influence on a probe pulse with molecular phase modulation（MPM） effect. By comparing the two compression methods, we summarize their advantages and drawbacks to obtain the few-cycle pulses with micro- or millijoule energies. It is also shown that the double pump-probe approach can be used as a tunable dual-color source by adjusting the time delay between pump and probe pulses to proper values.

The Modified CHHE-MRT Method in Few-Body System

Based on the continuum hyperspherical harmonics expansion momentum rep-resentation transformation(CHHE-MRT)method,a new approach is proposed to cal-culate the matrix elements of any forms of potential.By introducing the modifiedCHHE-MRT function,the 3N dimensional Bessel oscillatory integral appearing in po-tential calculation can be reduced to 3M dimension(N≥M).The method presentedhere can be used not only for bound stute but also for scattering state in few-body sys-tem.

Validation of TRMM and FEWS Satellite Rainfall Estimates with Rain Gauge Measurement over Ashanti Region, Ghana

Satellite rainfall estimates have predominantly been used for climate impact studies due to poor rain gauge network in sub-Saharan Africa. However, there are limited microscale studies within the sub-region that have assessed the performance of these satellite products, which is the focus of the present study. This paper therefore considers validation of Tropical Rainfall Measuring Mission (TRMM) and Famine Early Warning System (FEWS) satellite estimates with rain gauge measurements over Ashanti region of Ghana. First, a consistency assessment of the two gauge data products, the Automatic Rain Gauge (ARG) and Ghana Meteorological Agency (GMet) Standard Rain Gauge (SRG) measurements, was performed. This showed a very good agreement with correlation coefficient of 0.99. Secondly, satellite rainfall products from TRMM and FEWS were validated with the two gauge measurements. Validation results showed good agreement with correlation coefficients of 0.6 and 0.7 for TRMM and FEWS with SRG, and 0.87 and 0.86 for TRMM and FEWS with ARG respectively. Probability Of Detection (POD) and Volumetric Hit Index (VHI) were found to be greater than 0.9. Volumetric Critical Success Index (VCSI) was 0.9 and 0.8 for TRMM and FEWS respectively with low False Alarm Ratio (FAR) and insignificant Volumetric Miss Index (VMI). In general, relatively low biases and RMSE values were observed. The biases were less than 1.3 and 0.8 for TRMM and FEWS-RFE respectively. These indicate high rainfall detection capabilities of both satellite products. In addition, both TRMM and FEWS were able to capture the onset, peak and cessation of the rainy season, as well as the dry spells. Although TRMM and FEWS sometimes under/overestimated rainfall, they have the potential to be used for agricultural and other hydro-climatic impact studies over the region. The Dynamic-Aerosol-Cloud-Chemistry Interactions in West Africa (DACCIWA) project will provide an improved spatial gauge network database over the study area to enhance future validation and other climate impact studies.

Amplification of a Few Cycle Optical Pulses in Graphene

This paper focuses on the propagation of a few cycle optical pulses in graphene in a case of electromagnetic field. Electrons in the quantum formalism were considered and a change of dispersion law with Coulomb repulsion was taken into account. The effective equation was numerically analyzed and an influence of Coulomb repulsion was found. The amplification of few cycle optical pulses in graphene with applying of electromagnetic field to our system was discovered. Results about the amplification of pulse in graphene have been achieved.

APS-FeW适用于无线网络的TCP增强方案

TCP的控制隐含了一个假设，即分组丢失都是由网络拥塞引起的，而这一点对于无线网络不成立。因此在无线情况下，会引入了冗余控制，使得传输性能下降。浮点窗口算法（FeW）通过限制TCP的分组注入量，减少冗余控制，在此基础上，提出了改进方案自适应包长算法（APS）。仿真数据表明，基于FeW的APS算法（APS-FeW）比FeW算法提升了10％～25％的吞吐量。

基于局部特征深度信息的绝缘子小样本缺陷检测

基于深度学习的目标检测技术已广泛应用于绝缘子缺陷检测中,然而现有目标检测算法主要基于大量缺陷样本训练网络模型,无法对少样本缺陷进行准确识别。针对绝缘子缺陷检测过程中缺陷样本量不足的问题,该文提出了一种基于局部特征深度信息的绝缘子小样本缺陷检测方法。首先采用旋转目标检测网络改进Faster R-CNN(faster region-based convolutional neural network)模型提取绝缘子串区域,然后对绝缘子串特征进行划分,提取绝缘子串局部特征并基于深度推土距离(deep earth mover’s distance,Deep EMD)网络实现小样本缺陷检测。实验结果表明,在玻璃绝缘子自爆缺陷检测中,所提出方法采用2张训练样本可取得与现有目标检测方法 200张训练样本相同的效果,采用10张训练样本的绝缘子自爆检测在与真值框的交并比阈值为0.5至0.95之间的平均精度(mean average precision,mAP)达到0.65,该方法为小样本电力设备缺陷智能化检测提供了新的方法和思路。