Feature analysis of women's wedding dresses in new,style weddings in the Wu culture region in modern times北大核心CSCD

To further clarify the features of wedding dresses in new, style weddings in cities and towns of the Wu culture region, the author sorted out and made a statistical analysis of modern journals and periodicals as well as conducted a comparison in combination with diaries of celebrities and novels in modern times to collect 368 wedding photos in total in the Wu culture region. The analysis results indicate that wedding dresses in the Wu culture region were mainly of modified styles from 1859 to 1949, the development of wedding dresses went through the stages of unitary styles, mixed styles and diversified styles, in each of which there were also representative regular ways of matching. In general, wedding dresses were in simple, elegant and delicate styles, and the silhouettes kept up with popular western styles, showing a high level of acceptance of foreign cultures. The colors of wedding dresses tended to combinations of light colors, while traditional colors were gradually reduced. Besides, patterns of flowers and plants with thin stems and leaves were mainly used to decorate wedding dresses, showing the distribution features of scattering and covering. © 2018 China Silk Association. All rights reserved.     

An Improved On-line Contingency Screening for Power System Transient Stability Assessment

This paper presents a contingency screening method and a framework for its on-line implementation. The proposed method carries out contingency screening and on-line stability assessment with respect to first-swing transient stability. For that purpose, it utilizes the single machine equivalent method and aims at improving the prior developed contingency screening approaches. In order to determine vulnerability of the system with respect to a particular contingency, only one time-domain simulation needs to be performed. An early stop criteria is proposed so that in a majority of the cases the simulation can be terminated after a few hundred milliseconds of simulated system response. The method’s outcome is an assessment of the system’s stability and a classification of each considered contingency. The contingencies are categorized by exploiting parameters of an equivalent one machine infinite bus system. A novel island detection approach, appropriate for an on-line application since it utilizes efficient algorithms from graph theory and enables stability assessment of individual islands, is also introduced. The New England and New York system as well as the large-scale model of the Continental-European interconnected system are used to test the proposed method with respect to assessment accuracy and computation time.     

Boosting the electrochemical performance of Li-garnet based all-solid-state batteries with Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> electrode: Routes to cheap and large scale ceramic processing

All-solid-state batteries based on fast Li⁺ conducting solid electrolytes such as Li₇La₃Zr₂O₁₂ (LLZO) give perspective on safe, non-inflammable, and temperature tolerant energy storage. Despite the promise, ceramic processing of whole battery assemblies reaching close to theoretical capacities and finding optimal strategies to process large-scale and low cost battery cells remains a challenge. Here, we tackle these issues and report on a solid-state battery cell composed of Li₄Ti₅O₁₂ / c-Li_6.25Al_0.25La₃Zr₂O₁₂ / metallic Li delivering capacities around 70–75 Ah/kg with reversible cycling at a rate of 8 A/kg (for 2.5–1.0 V, 95 °C). A key aspect towards the increase in capacity and Li⁺ transfer at the solid electrolyte-electrode interface is found to be the intimate embedding of grains and their connectivity, which can be implemented by the isostatic pressing of cells during their preparation. We suggest that simple adaption of ceramic processing, such as the applied pressure during processing, strongly alters the electrochemical performance by assuring good grain contacts at the electrolyte-electrode interface. Among the garnet-type all-solid-state ceramic battery assemblies in the field, considerably improved capacities and cycling properties are demonstrated for Li₄Ti₅O₁₂ / c-Li_6.25Al_0.25La₃Zr₂O₁₂ / metallic Li pressed cells, giving new perspectives on cheap ceramic processing and up-scalable garnet-based all-solid-state batteries.     

Estimation of the error and interference immunity of the analog-to-digital conversion path in automatic control systems

A technique has been devised for determination of the error and interference immunity of the analog- to-digital conversion path in automatic control systems using moving digital averaging. The estimates of the errors and interference immunity of the analog-to-digital conversion path under the moving averaging have been analyzed and compared with the corresponding estimates obtained under averaging within the time-sampling interval and in the absence of averaging. Effective analytical expressions have been obtained to analyze the estimates of the errors and interference immunity of the analog-to-digital conversion of stationary random signals and additive interference. The calculated errors for various differentiable and nondifferentiable random signals given by autocorrelation functions have been analyzed. The influence of the number of the averaged readouts of the random signal and the time-sampling interval on the estimates of the errors and interference immunity have been investigated. The advantage of the moving averaging over the averaging within the time-sampling interval has been demonstrated. The calculated ratios allow, with the known signal and interference models and preset permissible-error estimate, selecting the parameters of the conversion path, i.e., the time-sampling interval, the number of the readouts of the converted sum of the random signal and interference under the averaging, and the effective number of bits of the analog-to-digital converter, under the conditions when the lag error cannot be excluded and the latter is excluded. The equations that allow the evaluation of the interference immunity of the conversion path are provided.     

特大城市地区如何引领实现百年目标

正吴唯佳(中国城市规划学会常务理事,清华大学建筑学院教授,本学术对话主持人):在2020年全面建成小康社会、实现第一个百年目标后,我国将为2049年实现第二个百年目标,建设现代化强国而奋斗。北京、天津、武汉等城市此前已开始加强2049战略研究。特大城市地区是以特大城市为核心,大中小城市相结合的城市密集地区,是我国现代化、城市化的战略引领地区。如何肩负使命,总结经验,认识规律,引领实现     

Spatial model selection strategies in a SUR framework. The case of regional productivity in EU

The purpose of the paper was to compare two well-known model selection strategies, the so-called Specific-to-General, Stge, and General-to-Specific, Gets, in a context of spatial SUR models. The two strategies use a battery of misspecification tests obtained in a maximum likelihood framework. The robust tests to local misspecification errors in the alternative hypothesis and the common factor test have been developed with this purpose. The paper includes a Monte Carlo experiment to compare their performance in a situation of small sample sizes. The results are mixed: Both alternatives work well under ideal conditions, but their efficiency deteriorates for different departures such as non-normality or endogeneity. All in all, Stge appears to be slightly preferable although our impression is that the two are complementary and can be used in common. The paper finishes with an application to the case of productivity for a large set of European regions.     

High Temperature Oxidation Behavior of Conventional and Nb-Modified MAR-M246 Ni-Based Superalloy

The present investigations focused on the thermal oxidation of two variants of MAR-M246 alloy having the same contents of Ta and Nb in at. pct, considering the effects of total replacement of Ta by Nb. The alloys were produced by investment casting using high purity elements in induction furnace under vacuum atmosphere. The alloys were oxidized pseudo-isothermally at 800 °C, 900 °C and 1000 °C up to 1000 hours under lab air. Protective oxidation products growing on the surface of the oxidized samples were mainly Al₂O₃, Cr₂O₃. Other less protective oxide such as spinels (NiCr₂O₄ and CoCr₂O₄) and TiO₂ were also detected as oxidation products. The conventional alloy exhibited slight internal oxidation at 800 °C and an enhanced resistance at 900 °C and 1000 °C. The Nb-modified alloy presented an exacerbated internal oxidation and nitridation at 900 °C and 1000 °C and an enhanced resistance at 800 °C. At 1000 °C, Nb-modified alloy was particularly affected by excessive spalling as the main damage mechanisms. From a kinetic point of view, both alloys exhibit the same behavior at 800 °C and 900 °C, with k_p values typical of alumina forming alloys (2 × 10⁻¹⁴ to 3.6 × 10⁻¹³ g² cm⁻⁴ s⁻¹). However, Ta modified alloys exhibited superior oxidation resistance at 1000 °C when compared to the Nb modified alloy due to better adherence of the protective oxide scale.

     

Substrate Stimulated Orientation for Pure Aluminum

Oriented materials are of great importance, but their formation is rarely described. Here, nine Al/Al₂O₃ systems were designed to identify the dominant factors. Electron back-scattered diffraction indicates that the new Al crystal(s) with one or multiple orientation(s) can be stimulated by one single-crystal Al₂O₃ substrates. Synchrotron radiation diffraction shows that the preferred orientation(s) is/are determined based on the initial stage of the liquid–solid transition. The nonpreferred orientation can be suppressed through competition.