类泛素蛋白及其中文命名

泛素家族包括泛素及类泛素蛋白,约20种成员蛋白.近年来,泛素家族领域取得了迅猛发展,并已与生物学及医学研究的各个领域相互交叉.泛素家族介导的蛋白质降解和细胞自噬机制的发现分别于2004和2016年获得诺贝尔奖.但是,类泛素蛋白并没有统一规范的中文译名. 2018年4月9日在苏州召开的《泛素家族介导的蛋白质降解和细胞自噬》专著的编委会上,部分作者讨论了类泛素蛋白的中文命名问题,并在随后的\"泛素家族、自噬与疾病\"(Ubiquitinfamily,autophagy anddiseases)苏州会议上提出了类泛素蛋白中文翻译草案,此草案在参加该会议的国内学者及海外华人学者间取得了高度共识.冷泉港亚洲\"泛素家族、自噬与疾病\"苏州会议是由美国冷泉港实验室主办、两年一度、面向全球的英文会议.该会议在海内外华人学者中具有广泛影响,因此,参会华人学者的意见具有一定的代表性.本文介绍了10个类别的类泛素蛋白的中文命名,系统总结了它们的结构特点,并比较了参与各种类泛素化修饰的酶和它们的生物学功能.文章由45名从事该领域研究的专家合作撰写,其中包括中国工程院院士1名,相关学者4名,长江学者3名,国家杰出青年科学基金获得者18名和美国知名高校华人教授4名.他们绝大多数是参加编写即将由科学出版社出版的专著《泛素家族介导的蛋白质降解和细胞自噬》的专家

Research of 3D Vision Observation and Visualization on Micro Scale

微观尺度下的观测与操作是进行微纳米科学技术研究与实现、微纳米特性发现与利用、加工制造的重要技术手段。因此微纳米操作的关键技术问题主要包括两个方面：微纳米操作的观测成像，通过成像微纳米尺度下的物体可以被观测者所感知和观测；利用感知与观测信息指导微纳米尺度下机械操作控制。深度信息在计算机视觉的研究中占有着重要的地位，它使我们更好地理解现实世界中物体的3D关系。因此，利用深度信息实现3D测量逐渐被应用于微纳米操作的观测成像领域。工作域显微图像是唯一能反映被控目标体运动和位置的反馈信息，自然对象的深度信息也只能从此中获得。虽然很难自动地从这个平面图像中获得，但根据显微镜点扩散模型的光学特点，可以构造合理的模糊度判据，实现对象深度信息恢复。本文作者以微观尺度下的3D视觉观测与可视化为应用背景，通过分析几何光学成像中的各种成像规律。建立图像的模糊度判据，并利用该判据完成了微观尺度下的3D视觉观测与可视化。主要工作包括： (1)分析光学成像的基本原理，了解光学成像过程中聚焦和离焦成像现象发生条件和描述方法；找到图像清晰/模糊程度与景物深度之间的关系，进而给出离焦理论依据； (2)分析不同测度算子的测量范围和精度要求； (3)分利用景物的清晰/模糊程度，测量微纳米操作中工作域反馈图像的深度信息，完成微观尺度下的3D视觉观测和可视化。本文就微纳米技术研究中的显微成像离焦现象进行了分析，给出了建立基于模糊测度的微米尺度下离焦度与景物深度信息关系的方法；分析了不同梯度算子所具有的不同模糊测度响应；并以实验验证了利用这种模糊测度可以对微观尺度下的景物进行深度信息获取,并且利用深度信息进行3D重建

The Influence of Metastable Cellular Structure on Deformation Behavior in Laser Additively Manufactured 316L Stainless Steel

Metastable cellular structures (MCSs) play a crucial role for the mechanical performance in concentrated alloys during non-equilibrium solidification process. In this paper, typifying the heterogeneous 316L stainless steel by laser additive manufacturing (LAM) process, we examine the microstructures in cellular interiors and cellular boundaries in detail, and reveal the interactions of dislocations and twins with cellular boundaries. Highly ordered coherent precipitates present along the cellular boundary, resulting from spinodal decomposition by local chemical fluctuation. The co-existences of precipitates and high density of tangled dislocations at cellular boundaries serve as walls for extra hardening. Furthermore, local chemical fluctuation in MCSs inducing variation in stacking fault energy is another important factor for ductility enhancement. These findings shed light on possible routines to further alter nanostructures, including precipitates and dislocation structures, by tailoring local chemistry in MCSs during LAM

Global depth from defocus with fixed camera parameters

利用2维离焦图像恢复景物的3维深度信息是计算机视觉中一个重要的研究方向。但是,在获取不同程度的离焦图像时,必须改变摄像机参数,例如,调节摄像机的焦距、像距或者光圈大小等。而在一些需要高倍放大观测的场合,使用的高倍精密摄像机的景深非常小,任何摄像机参数的改变都会对摄像机产生破坏性的后果,这在很大程度上限制了当前许多离焦深度恢复算法的应用范围。因此,提出了一种新的通过物距变化恢复景物全局深度信息的方法。首先,改变景物的物距获取两幅离焦程度不同的图像,然后,利用相对模糊度及热辐射方程建立模糊成像模型,最后,将景物深度信息的计算转化成一个动态优化问题并求解,获得全局景物深度信息。该方法不需改变任何摄像机参数或者计算景物的清晰图像,操作简单。仿真试验和误差分析结果表明,该方法可以实现高精度的深度信息恢复,适合应用于微纳米操作、高精度快速检测等对摄像机参数改变较为敏感的场合

Automatic water line detection for an USV system

Real-time and accurate detection of the sailing area or water area is an enabling technique for an unmanned surface vehicle (USV) system. However, research on water line detection based on optical images is rare, and current water line detection method is difficult to be used in real application. An automatic water line detection method based on optical images is proposed and validated with a practical USV system. First, the basic principle of structure extraction is introduced to preprocess the original river images so that the textures resulted from the USV motion, wind and illumination is removed; Then, gray level co-occurrence matrix (GLCM) and local binary patterns (LBP) are combined to calculate the texture information of the river images, and a water line detection method is proposed based on the entropy indicator and Hough transformation. Finally, the water lines of many practical images captured by our USV system moving on an inland river are tested with our new proposed detection method. The results show that the proposed algorithm is an effective method for detecting the complicated water lines in real applications

Shadow verification–based waterline detection for unmanned surface vehicles deployed in complicated natural environment

Boundary separation of operational regions would be helpful for unmanned surface vehicles deployed in dynamic outdoor environments. However, the feasibility and accuracy of current obstacle avoidance methods based on conventional optical images are comparatively poor for unmanned surface vehicle applications, with complicated natural illumination as one of the main sources of error. In this article, a new optical waterline detection method is proposed by combining shadow verification and global optimization (energy minimization). The method is then validated using an actual unmanned surface vehicle operating in outdoor environments. First, the basic principles of intrinsic image are introduced and then employed to evaluate the threshold for background segmentation so that the influence of complicated intensity distribution on the original image is reduced. The properties of different types of shadows are compared, and the basic principles of shadow verification are used to classify the different object regions. Subsequently, the intensity contrast between the shadow and non-shadow regions is used to measure the waterline position based on the relationship between the illumination and the shadow formation. Furthermore, the waterline detection problem is transformed into a problem involving the optimization of energy (minimization) described using differential equations. Finally, experiments are conducted with a series of practical images captured by the unmanned surface vehicle. The experimental results demonstrate the feasibility and robustness of the proposed method.</p

Shape reconstruction within an optical diffusion model

Shape reconstruction with an optical diffuser has some significant advantages such as high-precision depth estimation with a small lens, depth estimation for distant objects, and less sensitivity to lens aberrations. However, no optical diffusion model has been proposed to relate depth information to the basic principle of intensity distribution during optical diffusion. In this paper, heat diffusion equation in physics is introduced into optical diffusion, and a mathematic model of intensity distribution during optical diffusion is constructed. A high-precision shape reconstruction method with optical diffusion is proposed based on heat diffusion equation. First, an optical diffusion model is introduced to explain the basic principle of diffusion imaging process. Second, a novel shape reconstruction method based on global heat diffusion is proposed within our optical diffusion model. Finally, simulation with synthetic images and experiment with five playing cards are conducted, and the result proves the effectiveness and feasibility of the proposed method

Waterline Separation in Optical Images with Heavy Complicated Shadows

Accurate waterline separation of the sailing area is the base of unmanned surface vehicle (USV) systems moving in a complicated environment. However, shadows resulted from different natural illumination is one of the main error sources. This paper proposes a waterline separation method based on shadow processing with respect to optical images and presents a practical application to a USV system for validation. First, the basic principles of an intrinsic image is used to reduce the intensity influence of different shadows. Then, segmentation and shadow verification based on shadow analysis were introduced to separate and classify shadow regions. Finally, the problem of waterline separation is transformed into an optimization problem of mathematical energy minimum described by differential equations. In the practical application, the waterlines of many images captured by an USV system moving along an inland river are separated with the proposed method, and the experimental results showed that the proposed algorithm is effective and robust.</p

Statistical analysis on rolling contact fatigue in railroad axle bearing steel

High-strength steels are widely used in high-performance bearings utilized in most mechanical systems. However, there has been little statistical analysis regarding the fatigue failure behaviour of the material, where surface peeling resulted from contact fatigue during rolling is a significant life-limiting mechanism. In this study, we examine the statistical behaviour of surface-crack nucleation, propagation, and peeling in a high-speed train axle bearing made of GCr15 steel by using a laboratory rolling-contact equipment. We reveal that cyclic rolling-contact leads to the formation of a hardness gradient in the outer ring of the bearing. The gradient layer is of several millimetres. The peeling rate could be as high as 28 mu m per million cycles when the contact pressure is close to that applied in real service. Peeling-induced cracking is dominantly transgranular. The incipient angle is about 23.2 degrees, and its depth could be hundreds of micrometres. The findings reported here could be employed to assess the lifetime of bearings made of GCr15 steel and possible other engineering metals

Research on auto-feeding approach of AFM based on image autofocus

原子力显微镜(AFM)是纳米科学技术领域中的常用工具。AFM扫描成像前需要手动或半自动操作步骤实现探针与样品逼近过程,自动化程度低、操作繁琐,探针容易受损。由此,提出了一种粗精结合的分段式自动定位方法。在粗定位阶段,采用自动聚焦定位方法,提出了一种最强边缘拉普拉斯算子均值算法,具有很强的抗噪性能,可以适应AFM长行程、不同纹理样品自动聚焦,以确定探针和样品的相对位置;精定位阶段,采用精确力反馈控制方法,当样品和探针作用力超过设定值时,探针在Z向纳米平台的带动下能够自动回退,使针尖得到有效保护。通过这两种方法的有效技术融合,可以实现探针-样品逼近过程的自动化操作,提高AFM的易用性和使用效率。</p