结合时间戳的指纹密钥数据加解密传输方案

目的 对于生物密钥而言，生物特征数据的安全与生物密钥的管理存储都很关键。为了构造能够应用在通信数据传输场景的生物密钥，同时保证生物特征本身的模糊性与密码学的精确性处于一种相对平衡状态，提出一种基于时间戳与指纹密钥的数据加解密传输方案。方法 利用发送方指纹特征点之间的相对信息，与保密随机矩阵生成发送方指纹密钥；借助通信双方的预先设定数与时间戳，生成接收方恢复指纹密钥时所需的辅助信息；利用发送方指纹密钥加密数据，实现密文数据的传输。结果 本文方法在仿真通信双方数据加解密的实现中，测试再生指纹密钥的识别率（GAR）与误识率（FAR）。通过实验数据分析，表明了本文提出的指纹密钥生成方法的可用性，以及指纹密钥作为数字身份所具备的可认证性，其中真实发送方的再生指纹密钥识别率可高达99.8%，并且本方案还可用于即时通信、对称加密等多种场景当中。结论 本文方法利用时间戳确定了通信事件的唯一性与不可否认性，同时实现了指纹密钥恢复时的"一次一密"。此外，方案通过保密随机矩阵实现了发送方指纹密钥的可撤销，极大程度保障了指纹数据的安全性。     

A survey on analysis and implementation of state-of-the-art haze removal techniques

Haze is a poor-quality state described by the opalescent appearance of the atmosphere which reduces the visibility. It is caused by high concentrations of atmospheric air pollutants, such as dust, smoke and other particles that scatter and absorb sunlight. The poor visibility can result in the failure of multiple computer vision applications such as smart transport systems, image processing, object detection, surveillance etc. One of the major issues in the field of image processing is the restoration of images that are corrupted due to different degradations. Typically, the images or videos captured in the outside environment have low contrast, colour fade and restricted visibility due to suspended particles of the atmosphere that directly influence the image quality. This can cause difficulty in identifying the objects in the captured hazy images or frames. To address this problem, several image dehazing techniques have been developed in the literature, each of which has its own advantages and limitations, but effective image restoration remains a challenging task. In recent times, various learning (Machine learning & Deep learning) based methods greatly condensed the drawbacks of manual design of haze related features and reduces the difficulty in efficient restoration of images with less computational time and cost. The current state-of-the-art methods for haze free images, mainly from the last decade, are thoroughly examined in this survey. Moreover, this paper systematically summarizes the hardware implementations of various haze removal methods in real time. It is with the hope that this current survey acts as a reference for researchers in this scientific area and to provide a direction for future improvements based on current achievements.     

配分时间对Q&P钢组织及性能的影响

在传统C-Mn-Si钢的基础上,采用在线热处理,并通过光学显微镜、扫描电镜、拉伸试验等对一步淬火配分处理后试验钢的微观组织及力学性能进行了研究,且讨论了配分时间对材料组织性能的影响。结果表明:试验钢组织由板条马氏体和残留奥氏体组成,随着配分时间的增加,也有少量贝氏体生成,残留奥氏体含量先上升后下降,马氏体的板条组织逐渐模糊并软化;抗拉强度和屈服强度都逐渐降低,伸长率先升高后降低。配分30 s时综合性能最佳,抗拉强度为989 MPa,伸长率为23.5%,强塑积达到23.24 GPa·%。     

人工湿地-微生物电解池耦合系统的脱氮特性

实验构建了人工湿地-微生物电解池耦合系统（CW-MEC），并考察了CW-MEC在阴极有无曝气及不同水力停留时间（HRT）的条件下对生活污水的处理效果。实验结果显示，降低HRT会让CW-MEC阴极、阳极的COD去除率由91.11%±7.76%、86.58%±9.54%降低为77.81%±14.84%、81.44%±11.11%，氨氮去除率由58.54%±5.80%、58.22%±5.03%降低为48.04%±12.94%、48.27%±13.40%；阴极增加曝气会让CW-MEC阴极、阳极的COD去除率分别提高到89.51%±3.92%、82.40%±1.63%，阴极氨氮去除率提高到71.51%±16.44%，而阳极氨氮去除率不受影响；增加阴极曝气条件后，系统阴、阳极开始有硝酸盐氮积累，而CW-MEC阴极的硝酸盐氮含量明显低于对照组（CW-MFC）；通过电化学性能分析，相对于CW-MFC系统，CW-MEC具有更低的内阻；通过微生物多样性分析，CW-MEC系统具有更丰富的微生物多样性。     

质子交换膜燃料电池电化学阻抗谱弛豫时间分布研究

电化学阻抗谱技术能够获取燃料电池不同频率阻抗，但对阻抗的构成缺乏进一步解析，难以直接构建精准的等效电路模型进行阻抗拟合分析，而弛豫时间分布（Distribution of relaxation time，DRT）方法不需要定义特定的等效电路模型，即可解析燃料电池不同时间常数的极化过程。针对实验室用质子交换膜燃料电池，在不同运行条件下对其进行阻抗谱测量，并通过Kramers-Kronig关系验证所记录阻抗数据的质量。基于DRT分析方法，系统地解释阻抗谱中各频段阻抗对应的物理或化学意义。研究表明，该电池的电化学阻抗谱主要由3个不同时间常数频段的极化阻抗构成，通过与运行条件相关性的系统分析，确定低频段阻抗为氧气在多孔介质中的传输阻碍，中频段阻抗为与氧还原反应有关的电荷传递阻碍，中高频段阻抗为阴极催化剂层中的质子传输阻碍。为进一步确定DRT分析结果的合理性，采用等效电路模型拟合测量的阻抗数据，辨识的电阻元件参数变化趋势与DRT分析结果一致。     

Robustness analysis and distributed control of a networked system with time-varying delays

This paper is concerned with the robustness analysis and distributed output feedback control of a networked system with uncertain time-varying communication delays. This system consists of a collection of linear time-invariant subsystems that are spatially interconnected via an arbitrary directed network. Using a dissipation inequality that incorporates dynamic hard IQCs (integral quadratic constraints) for the delay uncertainties, we derive some sufficient robustness conditions in the form of coupled linear matrix inequalities, in which the coupled parts reflect the interconnection structure of the system. We then provide a procedure to construct a distributed controller to ensure the robust stability of the closed-loop system and to achieve a prescribed $\ell_2$-gain performance. The effectiveness of the proposed approach is demonstrated by some numerical examples.     

Agreement and repeatability of four different devices to measure non-invasive tear breakup time (NIBUT)

PurposeSince tear film stability can be affected by fluorescein, the Dry Eye Workshop (DEWSII) recommended non-invasive measurement of tear breakup time (NIBUT). The aim of this study was to investigate the agreement and repeatability of four different instruments in the measurement of NIBUT.Methods72 participants (mean 24.2 ± 3.6 years) were recruited for this multi-centre, cross-sectional study. NIBUT was measured three times from one eye using each of the instruments in randomized order on two separate sessions during a day, separated by at least 2 h. NIBUT was performed at three sites (Switzerland, Germany and UK) using three subjective instruments, Tearscope Plus (Keeler, Windsor, UK) (TS), Polaris (bon Optic, Lübeck, Germany) (POL), EasyTear Viewplus (Easytear, Rovereto, Italy) (ET) and the objective Keratograph 5 M (Oculus Optikgeräte GmbH, Wetzlar, Germany) (KER). As the latter instrument only analyses for 24 s, all data was capped at this value.ResultsNIBUT measurements (average of both sessions) between the four instruments were not statistically significantly different: TS (median 10.4, range 2.0–24.0 s), POL (10.1, 1.0–24.0 s), ET (10.6, 1.0–24.0 s) and KER (11.1, 2.6–24.0 s) (p = 0.949). The objective KER measures were on average (1.2 s ± 9.6 s, 95 % confidence interval) greater than the subjective evaluations of NIBUT with the other instruments (mean difference 0.4 s ± 7.7 s, 95 % confidence interval), resulting in a higher limits of agreement. The slope was -0.08 to 0.11 indicating no bias in the difference between instruments with the magnitude of the NIBUT. Repeated measurements from the two sessions were not significantly different for TS (p = 0.584), POL (p = 0.549), ET (p = 0.701) or KER (p = 0.261).ConclusionsThe four instruments evaluated for their measurement of tear stability were reasonably repeatable and give similar average results.     

偏高岭土-矿渣-磷渣地聚合物配比性能的研究

通过正交实验的方法，以地聚合物稠度、凝结时间、胶砂强度为研究依据，以偏高岭土、矿渣、磷渣、碱激发剂用量为研究对象，每个因素取3个水平，分析4个因素在各自水平上对地聚合物性能的影响。试验结果表明，偏高岭土用量是地聚合物稠度的最主要影响因素；偏高岭土和碱激发剂用量是初凝时间的主要影响因素，磷渣和偏高岭土用量是终凝时间的主要影响因素；偏高岭土用量是3 d 抗压强度的主要影响因素，矿渣用量是28 d 抗压强度的主要影响因素。按30%偏高岭土-40%矿渣-30%磷渣-10%碱激发剂制备的地聚合物具有良好的抗碳化性能，但收缩率较普通硅酸盐水泥高。     

The effect of ignition delay time on the explosion behavior in non-uniform hydrogen-air mixtures

The purpose of this study is to examine the explosion characteristics of non-uniform hydrogen-air mixtures with turbulent mixing. In the experiment, hydrogen is first filled into a 20 L spherical chamber to a desired initial pressure, then air is introduced into the same chamber through a fast response solenoid valve, by adjusting the ignition delay time (t_d), i.e., the time period between the end of air injection and the action of ignition, the turbulent mixing strengthen (or called uniformity of hydrogen-air mixture) is then changed. The experimental results show that the explosions are overall enhanced as t_d decreases, which indicates that turbulence plays a leading role in enhancing the explosion behaviors. In addition, it is found that the effect of turbulence on p_max is more prominent in end-wall ignition than that in center ignition. This is because the heat loss per unit time is higher in end-wall ignition due to the flame front continuously contacts with inner wall of the chamber throughout the explosion process, although the explosion duration time t_e for both ignition cases is reduced when turbulence is introduced, heat loss reduction for end-wall ignition is generally larger than that in center ignition. Lately, a systematical analysis of the turbulent effect associated with various equivalence ratios on the explosion characteristics is conducted in end-wall ignition. Those experimental results illustrate that the turbulence-enhancing influence is more noticeable when hydrogen-air mixtures move toward the lower explosion limit. However, no significant influence of turbulence on explosion process can be found as combustible mixtures tend to the fuel-rich side. This is mainly because that when hydrogen-air mixtures tend to fuel-rich side, τ_e reduction caused by the presence of turbulence is relatively weak as compared with that under quiescent condition, resulting in heat loss during explosion process changes slightly, hence there is no significant impact on explosion parameters.     

基于时序数据的云网协同平台人工智能运维体系

云计算在企业应用中的拓展不但表现为平台规模的拓展，也表现为平台应用的延伸。“云网协同”和“微服务化”是当前企业云平台演进的重要趋势。随着企业信息化建设重要性的持续提升，微服务化云网协同平台的运行维护面临极大挑战。首先分析了平台运维面临的挑战，梳理了平台人工智能运维需求，提出了基于时序数据分析的平台人工智能运维技术体系，并给出了云网协同平台人工智能运维子系统参考设计。所提技术体系和系统设计具有实用性和推广性，可以作为企业云平台建设和优化的技术途径参考。