Multiferroic hexagonal ferrites (h-RFeO3_3, R=Y, Dy-Lu): an experimental review

Hexagonal ferrites (h-RFeO$_3$, R=Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO$_3$ rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature multiferroicity and predicted magnetoelectric effect, h-RFeO$_3$ are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic, and magnetoelectric properties of h-RFeO$_3$. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties

Uneven illumination surface defects inspection based on convolutional neural network

Surface defect inspection based on machine vision is often affected by uneven illumination. In order to improve the inspection rate of surface defects inspection under uneven illumination condition, this paper proposes a method for detecting surface image defects based on convolutional neural network, which is based on the adjustment of convolutional neural networks, training parameters, changing the structure of the network, to achieve the purpose of accurately identifying various defects. Experimental on defect inspection of copper strip and steel images shows that the convolutional neural network can automatically learn features without preprocessing the image, and correct identification of various types of image defects affected by uneven illumination, thus overcoming the drawbacks of traditional machine vision inspection methods under uneven illumination

Collective flow in 2.76 A TeV and 5.02 A TeV Pb+Pb collisions

In this paper, we study and predict flow observables in 2.76 A TeV and 5.02 A TeV Pb +Pb collisions, using the iEBE-VISHNU hybrid model with TRENto and AMPT initial conditions and with different forms of the QGP transport coefficients. With properly chosen and tuned parameter sets, our model calculations can nicely describe various flow observables in 2.76 A TeV Pb +Pb collisions, as well as the measured flow harmonics of all charged hadrons in 5.02 A TeV Pb +Pb collisions. We also predict other flow observables, including $v_n(p_T)$ of identified particles, event-by-event $v_n$ distributions, event-plane correlations, (Normalized) Symmetric Cumulants, non-linear response coefficients and $p_T$-dependent factorization ratios, in 5.02 A TeV Pb+Pb collisions. We find many of these observables remain approximately the same values as the ones in 2.76 A TeV Pb+Pb collisions. Our theoretical studies and predictions could shed light to the experimental investigations in the near future.Comment: 17 pages, 11 figure

Practical Techniques for Improving Performance and Evaluating Security on Circuit Designs

As the modern semiconductor technology approaches to nanometer era, integrated circuits (ICs) are facing more and more challenges in meeting performance demand and security. With the expansion of markets in mobile and consumer electronics, the increasing demands require much faster delivery of reliable and secure IC products. In order to improve the performance and evaluate the security of emerging circuits, we present three practical techniques on approximate computing, split manufacturing and analog layout automation. Approximate computing is a promising approach for low-power IC design. Although a few accuracy-configurable adder (ACA) designs have been developed in the past, these designs tend to incur large area overheads as they rely on either redundant computing or complicated carry prediction. We investigate a simple ACA design that contains no redundancy or error detection/correction circuitry and uses very simple carry prediction. The simulation results show that our design dominates the latest previous work on accuracy-delay-power tradeoff while using 39% less area. One variant of this design provides finer-grained and larger tunability than that of the previous works. Moreover, we propose a delay-adaptive self-configuration technique to further improve the accuracy-delay-power tradeoff. Split manufacturing prevents attacks from an untrusted foundry. The untrusted foundry has front-end-of-line (FEOL) layout and the original circuit netlist and attempts to identify critical components on the layout for Trojan insertion. Although defense methods for this scenario have been developed, the corresponding attack technique is not well explored. Hence, the defense methods are mostly evaluated with the k-security metric without actual attacks. We develop a new attack technique based on structural pattern matching. Experimental comparison with existing attack shows that the new attack technique achieves about the same success rate with much faster speed for cases without the k-security defense, and has a much better success rate at the same runtime for cases with the k-security defense. The results offer an alternative and practical interpretation for k-security in split manufacturing. Analog layout automation is still far behind its digital counterpart. We develop the layout automation framework for analog/mixed-signal ICs. A hierarchical layout synthesis flow which works in bottom-up manner is presented. To ensure the qualified layouts for better circuit performance, we use the constraint-driven placement and routing methodology which employs the expert knowledge via design constraints. The constraint-driven placement uses simulated annealing process to find the optimal solution. The packing represented by sequence pairs and constraint graphs can simultaneously handle different kinds of placement constraints. The constraint-driven routing consists of two stages, integer linear programming (ILP) based global routing and sequential detailed routing. The experiment results demonstrate that our flow can handle complicated hierarchical designs with multiple design constraints. Furthermore, the placement performance can be further improved by using mixed-size block placement which works on large blocks in priority

Analysis of two phase transient pressure from permanent down-hole gauges (PDG)

Currently many of the world’s mature fields have entered the middle-high water-cut period. At this stage, reservoir numerical simulation (RNS) becomes a powerful tool for reservoir management which allows the reservoir engineer to plan and evaluate future development options for the reservoir to carry out the ultimate goal of minimizing costs and maximizing economic returns. So the precision of RNS is crucial to the success of any development plan. A precise reservoir model, including a geological model and a fluid model, is the foundation of RNS. Hence, how to use all available history data (such as permanent down-hole gauges (PDG) data, production data, etc.) to calibrate a reservoir model is a huge challenge for reservoir management. In this thesis, the multiphase flow well testing problems encountered in reservoir management are studied. Based on analytical solutions, traditional multiphase flow well testing approaches are modified to make them suitable for special reservoirs. For non-uniform saturation reservoirs, some improved understandings of transient well testing have been synthetically developed. Before water breaks through, the transient pressure response in the transition zone of two phase flow systems is theoretically studied, and the results show that the pressure response in the transition zone is a function of the total effective mobility of the fluid. After water breaks through, the derivative of the bottom-hole pressure is a function of the integral of total mobility, which can be approximately replaced by the average total effective mobility. The trend of the BHP curve is controlled by the total mobility. For layered commingled reservoirs, the type curves of transient pressure data are obtained. According to these type curves, some improved understandings are developed. At the same time, the practicality of selective inflow performance methods (SIP) on field scale reservoir models is also discussed. Because of the limitation of analytical solutions, not all existing multiphase flow well testing approaches are fit for evaluating mature field cases. So based on numerical solutions, a new multiphase flow well testing procedure is developed. The overall conclusion to the work is that transient well test data or PDG data with multiphase flow effects should be used to improve the degree of accuracy of reservoir model and fulfill the ultimate goal of well testing of dynamic reservoir monitoring and managemen

Multiferroic hexagonal ferrites (h-RFeO3, R=Y, Dy-Lu): an experimental review

Hexagonal ferrites (h-RFeO3, R=Y, Dy-Lu) have recently been identified as a new family of multiferroic complex oxides. The coexisting spontaneous electric and magnetic polarizations make h-RFeO3 rare-case ferroelectric ferromagnets at low temperature. Plus the room-temperature mul- tiferroicity and predicted magnetoelectric effect, h-RFeO3 are promising materials for multiferroic applications. Here we review the structural, ferroelectric, magnetic, and magnetoelectric properties of h-RFeO3. The thin film growth is also discussed because it is critical in making high quality single crystalline materials for studying intrinsic properties

A Review on The Professional Development of Elementary Education Teachers in China

The school field is the main field of teachers' study and work, which creates the field space for teachers' professional development. In order to explore the situation of teacher professional development in school field,based on the general condition of the research, from the research scope, the research perspective, the fit between "teaching" and "learning" in the study and the discussion that the theoretical research focuses on the value of practice, we have sorted out the hot spots and trends of the research on the professional development of Primary and high school teachers in China from the perspective of school standard.In the subsequent analysis, we need to make further thinking or exploration in the five aspects of the origin and fulcrum of the research, the positioning of the study, the establishment of the research thinking, the consideration of the influential factors in the research and the enlightenment of the research methodology