Improving weld formability by a novel dual-rotation bobbin tool friction stir welding

A novel dual-rotation bobbin tool friction stir welding (DBT-FSW) was developed, in which the upper shoulder (US) and lower shoulder (LS) have different rotational speeds. This process was tried to weld 3.2 mm thick aluminum-lithium alloy sheets. The metallographic analysis and torque measurement were carried out to characterize the weld formability. Experimental results show that compared to conventional bobbin tool friction stir welding, the DBT-FSW has an excellent process stability, and can produce the defect-free joints in a wider range of welding parameters. These can be attributed to the significant improvement of material flow caused by the formation of a staggered layer structure and the unbalanced force between the US and LS during the DBT-FSW process.     

On‐the‐Spot Immobilization of Quantum Dots,Graphene Oxide,and Proteins via Hydrophobins

Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications.     

ZK60镁合金表面滚压强化试验研究

试验研究了ZK60镁合金表面滚压加工中工艺参数对试件表面粗糙度、表面形貌、表面残余应力和表层显微硬度的影响,结果表明滚压力和重复滚压次数对试件的表面粗糙度、表面形貌以及表面残余应力和表层硬度影响程度较大,滚压速度影响较小。对精车ZK60镁合金试件进行滚压加工,试件表面粗糙度R a、R z最大减小了50.3%和48.1%;残余压应力最大可达-54.55 MPa;显微硬度从试件表层到内部基体材料逐渐降低,表层硬度值最大为92.83 HV 0.25,比基体材料硬度提高了15.32%。     

Critical state model for structured soil

Structure is an evident determinant for macroscopic behaviors of soils. However, this is not taken into account in most constitutive models, as structure is a rather complex issue in models. For this, it is important to develop and implement simple models that can reflect this important aspect of soil behavior. This paper tried to model structured soils based on well-established concepts, such as critical state and sub-loading. Critical state is the core of the classic Cam Clay model. The sub-loading concept implies adoption of an inner (sub-loading) yield surface, according to specific hardening rules for some internal strain-like state variables. Nakai and co-workers proposed such internal variables for controlling density (ρ) and structure (ω), using a modified stress space, called t_ij. Herein, similar variables are used in the context of the better-known invariants (p and q) of the Cam Clay model. This change requires explicit adoption of a non-associated flow rule for the sub-loading surface. This is accomplished by modifying the dilatancy ratio of the Cam Clay model, as a function of the new internal variables. These modifications are described and implemented under three-dimensional (3D) conditions. The model is then applied to simulating laboratory tests under different stress paths and the results are compared to experiments reported for different types of structured soils. The good agreements show the capacity and potential of the proposed model.     

Broadband bowtie belt nanoantennas

In this article, we study a linear array of bowtie nanoantennas placed between two metallic strips that can work from 800 to 1420 nm (600 nm linewidth), with an electric field enhancement factor close to 20. We study the dynamical change of the position of the electric field enhancement amongst different elements in the array and, at the same time, the effects of dispersion on the scalability of the array elements. A systematic analysis and methodology to produce an array that can operate over a large bandwidth whilst maintaining the electric field enhancement without significant variation is provided.     

Behaviour of Surface Defects in Wire Rod Rolling

Defects are often present in rolled products, such as wire rod. The market demand for wire rod without any defects has increased. In the final wire rod products, defects originating from steel making, casting, pre‐rolling of billets and during wire rod rolling can appear. In this work, artificial V‐shaped longitudinal surface cracks have been analysed experimentally and by means of FEM. The results indicate that the experiments and FEM calculations show the same tendency except in two cases, where instability due to fairly “round” false round bars disturbed the experiment. FE studies in combination with practical experiments are necessary in order to understand the behaviour of the material flows in the groove and to explain whether the crack will open up as a V‐shape or if it will be closed as an I‐shape.     

首钢1号高炉增产节焦生产实践

对首钢1号高炉焦炭质量恶化后增产节焦的生产经验进行了总结分析。认为提高入炉原燃料质量，综合优化高炉基本制度，合理控制稳定的操作炉型是保证炉况长期顺稳、实现效益最大化的有效手段。     

Optoelectronic Method of Noncontacting Reconstruction of the Profile of a Surface of Three Dimensional Objects of Large Dimensions

An optoelectronic method is considered for noncontacting reconstruction of the surface profile of three-dimensional objects of large dimensions. The optimal conditions for performing measurements are identified. It is shown that the proposed method, in contrast to the already known methods, does not require fine tuning of the equipment. A numerical method is given for compensating distortions caused by aberrations. A method is described for reconstructing the surface profile cell by cell which increases the accuracy of measurements.     

DFIT测试在长庆气田开发中的应用

与常规的小型测试压裂不同，流体注入诊断测试（DFIT）是通过关井阶段出现的拟线性流或拟径向流阶段求取储层压力，采用改进的梅耶霍夫方法（M-method）解释储层渗透率。以长庆榆林气田一口开发井为例，依据DFIT的技术原理和测试步骤，对该井测试压降数据进行解释分析，结果可信度较高，证明了该项工艺在长庆低压低渗油气田的可行性。