Structure and mechanical properties of aluminum alloy/Ag interlayer/steel non-centered electron beam welded joints

Electron beam welding was carried out between aluminum alloy and steel with Ag interlayer. Seam morphology, structure and mechanical properties of the joints were investigated with different action positions of the electron beam spot. The results show that with the increment of the beam offset to the silver side from the interface between silver and steel, the seam morphology was improved, and the porosity in the Ag interlayer vanished. A transition layer mainly composed of Ag2Al and Al eutectic was formed at the interface between silver and aluminum, and became thin and spiccato as the beam offset increased. When the beam offset was too large, two IMC layers composed of FeAl and FeAl3 respectively were formed at the interface between steel and Ag interlayer. The optimal beam offset was 0.2 mm, and the maximum tensile strength of the joint was 193 MPa, 88.9% that of the aluminum alloy, and the fracture occurred at the interface between steel and Ag interlayer.

Short-term outcomes after the loading phase of intravitreal bevacizumab and subthreshold macular laser in non-center involved diabetic macular edema

AIM： To compare the effectiveness of intravitreal bevacizumab and subthreshold macular photocoagulation （SMP）, for the treatment of non-center involved diabetic macular edema （non-CI DME）. METHODS： Prospective, randomized, controlled clinical study included patients with type 2 diabetes, non-CI DME and best-corrected visual acuity （BCVA） of 0.30 logMAR or better. Each eye was randomized into three groups： group 1, monthly intravitreal bevacizumab; group 2, single SMP; group 3, single SMP and monthly bevacizumab. Main outcome measures were BCVA, and macular thickness measured with optical coherence tomography as macular central subfield thickness （CST）, macular area of greater thickness （MAGT） and total macular volume （TMV）. Results were analyzed after 3mo. RESULTS： A total of 32 eyes were included. Group 3 improved in BCVA （0.19±0.16 to 0.12±0.14 logMAR; P=0.041） and in TMV （7.90±0.57 to 7.65±0.73 mm3; P=0.025）. Group 1 improved in MAGT （325±26.26 to 298.20±44.85 μm; P=0.022） and TMV （7.79±0.57 to 7.50±0.56 mm3, P=0.047）. Group 2 didn’t show significant improvement of any variable. CONCLUSION： The loading phase of bevacizumab as monotherapy or combined with SMP is superior to SMP as monotherapy in providing short-term visual and anatomical improvement in non-CI DME.

动物解放论与以往动物保护主义之比较

动物保护伦理是环境伦理学中非人类中心主义流派里的一个重要分支。彼得.辛格的动物解放论是关于动物伦理的现代讨论中最有影响的理论之一。与以往以人类为中心的动物保护主义不同,动物解放主义的基本原则在于功利主义伦理学的平等原则和功利原则,它主张从“动物的解放是人类解放事业的继续”出发,把道德关怀的对象直接扩展到动物身上,从而让动物拥有道德地位,以此从外部、强制性地限制人对动物的伤害行为。

Investigations of microstructures and properties in electron beam welded joints of TiAl to TC4

The normally centered electron beam and non-centered electron beam welding of TiAl to TC4 was investigated in order to analyze the electron beam weldability between TiAl/TC4 dissimilar materials. Macroscopic cold crack easily occurred near TiAl substrate in the joints. The optimal tensile strength was related to the welding heat input. The weld structures were composed of bulky columnar grains and equiaxed grains. The isolated phases consisted of large quantities of α2 -Ti3Al phase, small quantity of B2 phase, γ-TiAl phase and YAl2 phase. Insufficient melting of the base metal occurred in the weld when the beam position leaned to the TC4 side. The tensile strength could be improved when the deflection was limited in the optimum range. Otherwise, non-fusion zone was easily generated in the weld, which led to the low tensile strength.

人类中心主义问题研究综述

伴随着科学技术的进步,工业化程度越来越高的同时,也产生了生态环境恶化等全球性问题。这些消极因素的出现,促使人们重新思考人与自然的关系,从而使人类中心主义的研究成为近年来的热门话题。文章选取了人类中心主义研究的几个主要问题,对我国学者研究的一些主要观点进行了概述。

Credibility protection for resource sharing and collaborating in non-center network computing environments

Non-center network computing environments have some unique characteristics, such as instability, heterogeneity, autonomy, distribution and openness, which bring serious issues of security and reliability. This article proposes a brand-new credibility protection mechanism for resource sharing and collaboration in non-center network computing environments. First, the three-dimensional hierarchical classified topology （3DHCT） is proposed, which provides a basic framework for realizations of the identity credibility, the behavior credibility and the capability credibility. Next, the agent technology is utilized to construct the credibility protection model. This article also proposes a new comprehensive credibility evaluation algorithm with simple, efficient, quantitative and able to meet the requirements of evaluating behavior credibility and the capability credibility evaluation as well. The Dempster-Shafer theory of evidence and the combination rule are used to achieve the evaluation of the capability credibility. The behavior credibility is evaluated with the current and historical performance of nodes for providers and consumers to realize more accurate prediction. Based on the non-center network computing simulation test platform, simulation is been conducted to test the performance and validity of the proposed algorithms. Experiment and analysis show that the proposed algorithms are suitable for large-scale, dynamic network computing environments, and able to maintain the credibility for networks without relying on central node, make a non-center network gradually evolve into an orderly, stable and reliable computing environment efficiently.