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In this study, a Ti-6Al-4V/Ni-Ti functionally graded material was successfully prepared by multi-wire arc additive manufacturing. Its microstructural, electrochemical, and mechanical properties were studied. The results show that the microstructure is transformed from an α-Ti + β-Ti basket structure to an NiTi columnar crystal. With an increase in Ni content, Icorrdecreases from 0.203 ± 0.017 μA/cm2to 0.145 ± 0.003 μA/cm2, and Ecorrincreases from −409 ± 5 mV to −259 ± 3 mV. The microhardness increases from 335 ± 7 HV0.2to 615 ± 17 HV0.2in the gradient region and then decreases to 250 ± 8 HV0.2. The ultimate compressive strength of the gradient region is 1253 ± 62 MPa.

Roll bending is a common technique to regulate the strip shape in tandem cold rolling (TCR), but its regulation ability at each stand is poorly understood at present. In this study, based on a 3D multiple stand elasto-plastic finite element (EPFE) model, the effects of work roll bending (WRB) and intermediate roll bending (IRB) on the strip crown, strip flatness and elastic deformation of work roll (WR) were quantitatively studied at each stand in the TCR. Results show that the regulation abilities of WRB and IRB on the strip crown both show a downward tendency from Stand 1 (S1) to Stand 5 (S5), which both depend on the strip plastic rigidity. Moreover, under various WRBs and IRBs, the strip shape is mainly determined by the elastic deflection of WR in the upstream stand, while it is determined combinedly by the elastic deflection and flattening deformation of WR in the downstream stand. Furthermore, the regulation ability of WRB on the strip crown and quadratic flatness is at least 2.5 times larger than that of IRB. The experimental results show that the developed multiple stand EPFE model can well predict the trend of the quadratic and quartic flatness between coils. These findings help understand the influence mechanism of the roll bending on the strip shape and improve the strip shape by optimising the roll bending in the TCR.

In modern multi-tenant data centers, each tenant desires reassuring dependability from the virtualized network fabric – bandwidth guarantee with work conservation, bounded tail latency and resilient reachability. However, the slow convergence of prior works under network dynamics and uncertainties can hardly provide the dependability for tenants. Further, state-of-the-art load balance schemes are guarantee-agnostic and bring great risks on breaking bandwidth guarantee, which is overlooked in prior works. In this paper, we propose vFab, a dependable virtualized fabric framework which can (1) quickly detect network failure in data plane, (2) explicitly select proper paths for all flows, and (3) converge to ideal bandwidth allocation at sub-millisecond. The core idea of vFab is to leverage the programmable data plane to build a fusion of an active edge (e.g., NIC) and an informative core (e.g., switch), where the core sends link status and tenant information to the edge via telemetry to help the latter make a timely and accurate decision on path selection and traffic admission. We fully implement vFab with commodity SmartNICs and programmable switches. Extensive evaluations show that vFab can keep bandwidth guarantee with high bandwidth utilization, low and bounded latency, and resilient reachability under various network scenarios with limited overhead. Application-level experiments show that vFab can improve QPS by $2.4\times $ and cut tail latency by $10\times $ compared to the alternatives.

Request latency directly affects the performance of modern cloud applications. Due to various causes in hosts and networks, requests can suffer from request latency anomalies (RLAs), which may violate the Service-Level Agreement. However, existing performance monitoring tools have incomplete coverage and inconsistent semantics for monitoring requests and cannot accurately diagnose RLAs. This paper presents BufScope, a high-coverage and low-overhead request event monitoring system, which monitors buffers to capture most RLA-related abnormal events with consistent request-level semantics in the end-to-end datapath of request. First, BufScope models the datapath of request as a buffer chain and defines events based on three properties of buffers, so as to end-to-end monitor the root causes of RLA. Then, to achieve consistent semantics for captured events, BufScope designs a request-level semantics injection mechanism to make events captured in networks have the victim requests’ ID. Finally, BufScope offloads the semantics operations and event collection in software to SmartNICs for low CPU overhead. We have implemented BufScope on commodity SmartNICs and programmable switches. Evaluation results show that BufScope can diagnose 98% RLAs with < 0.08% network bandwidth overhead and 0.6% application throughput decline.

During tandem hot rolling (THR), the rolling force plays an important role in strip shape control, but the influence mechanism of the rolling force on the strip shape is still currently unclear. This paper proposes a novel 3D multi-stand coupled thermo-mechanical finite element (FE) model for the THR developed employing a segmentation modelling strategy and data transfer technologies. This developed FE model has been validated by industrial experiments. Besides, the effects of rolling force on the strip shape (including strip crown and flatness) in the THR have been quantitatively studied. Results show that the strip crown increases with the rolling force at each stand, while the regulation efficiency of rolling force on the strip crown decreases continuously from (Finish stand 1) F1 to (Finish stand 7) F7, which is attributed to the significant increase in strip plastic rigidity from F1 to F7. Furthermore, lateral metal flow and strip plastic rigidity have a coupled effect on the regulation efficiency of rolling force on the strip flatness; more precisely, the regulation efficiency is mainly affected by the lateral metal flow in the upstream stand, while it is mainly influenced by the strip plastic rigidity in the downstream stand. These findings not only throw light on the influence mechanism of rolling force on the strip shape, but also offer a way to control and improve the strip shape by employing reasonable rolling force during industrial production.

The rotary table is a crucial component of the machine tool, and its accuracy and reliability have an important impact on the machining accuracy and machining efficiency of the machine tool. In this paper, a global reliability sensitivity analysis method of the rotary table is proposed considering the random uncertainty for material parameters of each component. Firstly, the mechanical model of the rotary table is established based on the finite element method. Subsequently, the functional relationship between the parameters of each component and the deformation of the rotary table is reconstructed using the adaptive Kriging surrogate model. Finally, a global reliability sensitivity analysis of the rotary table is performed based on the Bayesian formulation. The results show that the proposed global reliability sensitivity analysis method of the rotary table demonstrates satisfactory efficiency and can provide theoretical guidance for the design and optimization of the rotary table.

Numerous investigations have explored how the roll shifting affects the strip shape in hot strip mills (HSM). Nevertheless, the majority of these studies are constrained to a single pass. This study aims to investigate the effects of the work roll shifting (WRS) on the strip crown, strip flatness, and the loaded roll gap profile at each pass from the finishing stand No.1 (F1) to No. 7 (F7) in HSM, using a 3D multi-pass elasto-plastic thermo-mechanical coupled finite element (METCFE) model. The results indicate that as the WRS (with a three-order CVC contour) increases in the upstream stand, the quadratic flatness, characterized by the centre wave, strengthens at F1 and finishing stand No.2 (F2); however, at finishing stand No.3 (F3) and No. 4 (F4), the quadratic flatness transforms from the edge wave to the centre wave; by contrast, the quartic flatness hardly changes at each pass; furthermore, the regulation capacity of the WRS on the strip crown presents a declining tendency from F1 to F4, due to the increasing strip plastic rigidity within this range. Additionally, the WRS with a conventional contour has a negligible effect on the strip shape in the downstream stand. The industrial application cases indicate that the 3D METCFE model can precisely predict the trend of quadratic and quartic flatness differences among coils in full strip length. These findings enhance our understanding of the influence mechanism of the WRS on the strip shape in HSM, expanding from a single-pass analysis to a multi-pass context.

Thermal crown and wear crown of work roll (TWW) are the main interfering factors of loaded roll gap profile in tandem cold rolling (TCR). However, the effect of TWW on the strip shape is not well understood. This paper presents a quantitative study about the effect of TWW on the strip crown and strip flatness based on a novel 3D multi-pass elastic-plastic finite element (EPFE) model that has been validated by industrial trials in the TCR. The results show that the thermal crown introduces the centre wave and quarter wave, while the wear crown brings in the edge wave and edge-centre coupled wave; the thermal crown has a larger influence efficiency on the quadratic strip shape than the wear crown does, while the wear crown exerts a larger influence efficiency on the quartic strip shape than the thermal crown does. In addition, the influence efficiency of TWW on the strip crown decreases nonlinearly with an increase in strip plastic rigidity from Pass 1 (P1) to Pass 5 (P5). This is the first scientific report on the link between the strip plastic rigidity and the effect of TWW on the strip crown, affording the mathematical models for predicting the influence efficiency of TWW based on the strip plastic rigidity at each pass.

Articular chondrocytes are the main cell population in cartilage, and damage to them is a key step in osteoarthritis. There are chondrocyte-based strategies to treat osteoarthritis, among which includes nonviral gene therapy. However, so far there is no ideal way to achieve this because chondrocyte cells are very difficult to transfect. Also, an effective tracking system to evaluate exogenous DNA delivery in chondrocytes is a necessary part of this strategy. Here, we show our development of a novel tracking system by labelling cell membranes, nuclei, and plasmids, without disturbing their expression, to view the intracellular behaviour of plasmids before, after, and during the entire transfection process. We applied this system to compare the intracellular behaviour of exogenous DNA in chondrocytes and cancer cells. We also used this system to compare the intracellular behaviour of exogenous DNA which is transfected by liposomes or polymers. Finally, we discovered that when transfected by liposomes, exogenous DNA has a quicker cell entry and nucleus entry in cancer cells than in chondrocytes, and the transfection efficiency is higher in cancer cells than in chondrocytes. When the cells are transfected by polymers, exogenous DNA has the same quick cell entry and nucleus entry in both types of cells. However, the transfection efficiency was higher in cancer cells than in chondrocytes. Applying this system has proved to be simple, easy to operate, repeatable, and stable and it enables tracking of the behaviour of plasmid DNA before and after expression. Meanwhile, the rate-limiting zones of exogenous plasmid DNA in living cells and a comprehensive overview of the expression and transfection efficiency of DNA can also be obtained through this system, making it ideal for the research and development of nonviral DNA delivery systems.

Students, as one specific group of school stakeholders, have unique perceptions of school climate, which predict academic performance. In the Program for International Student Assessment 2009 Shanghai survey, 5,115 students from 152 schools participated. The results from this study showed that compared with their peers in the countries of the Organization for Economic Cooperation and Development, Shanghai students reported better teacher–student relationships, classroom disciplinary climate, and teacher stimulation of reading, although they had worse attitudes toward school. In line with prior literature, multilevel analyses in this study revealed that students' individual perceptions of school climate predicted reading achievement in Shanghai. Controlling for student background characteristics, these individual perceptions explained 1.71% of the within-school differences in reading achievement.

Many large content publishers use multiple content distribution networks to deliver their content, and many commercial systems have become available to help a broader set of content publishers to benefit from using multiple distribution networks, which we refer to as content multihoming. In this paper, we conduct the first systematic study on optimizing content multihoming, by introducing novel algorithms to optimize both performance and cost for content multihoming. In particular, we design a novel, efficient algorithm to compute assignments of content objects to content distribution networks for content publishers, considering both cost and performance. We also design a novel, lightweight client adaptation algorithm executing at individual content viewers to achieve scalable, fine-grained, fast online adaptation to optimize the quality of experience (QoE) for individual viewers. We prove the optimality of our optimization algorithms and conduct systematic, extensive evaluations, using real charging data, content viewer demands, and performance data, to demonstrate the effectiveness of our algorithms. We show that our content multihoming algorithms reduce publishing cost by up to 40%. Our client algorithm executing in browsers reduces viewer QoE degradation by 51%.

An electrochemical cross-dehydrogenative coupling of indoles with xanthenes has been established at room temperature. This coupling reaction could proceed in the absence of any catalyst or external oxidant, and generate the indole derivatives in moderate yields. Mechanistic experiments support that a radical pathway maybe involved in this reaction system.

N‐Benzylideneglycine esters and either maleates or maleimides undergo a [3+2] cycloaddition reaction under optimized conditions concerning the ligand, the iron salt, the solvent, and the reaction temperature to give the desired endo‐pyrrolidines with up to 78% enantioselectivity.

The key feature of the method is that the Pd species and ionic liquids are easily recovered and reused six times with constant activity.

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