中国货币政策的经验性分析:从数量型调控向价格型调控演进

经济和金融新形势下,中国货币政策表现为数量型调控为主转向价格型调控为主的渐进过程。本文首先从货币政策制度、目标、工具和传导机制四个维度对转型时期中国货币政策进行经验性分析,然后对货币政策转型时点进行严格的统计推断,据此建立多个分段的货币政策方程进行实证检验。研究表明:中国货币政策存在明显的结构性差异,采用单个线性方程抽象较长时期的中国货币政策是不合宜的;数量型方程与价格型方程在结构性断点、回归结果和模型解释力上均存在较大差异,因而建立量价混合的货币政策方程更契合中国货币政策实践。总的来看,中国货币政策框架是多元的,数量型工具仍发挥重要作用,市场利率调控尚不成熟,货币政策转型一直在路上且任重而道远。

数据驱动故障诊断方法泛化性能的经验性分析

近年来数据驱动的故障诊断方法被广泛研究,但是这些方法有效的一个前提条件是训练诊断模型的数据与待测试数据应需采集自相同的设备和运行环境,然而这个前提条件在实际的诊断情形中很难得到满足,实际能够用来训练诊断模型的通常是采集自同类型设备或不同工况的历史数据。对于实际诊断情形下存在潜在差异的数据集,数据驱动故障诊断方法是否有效的问题鲜有讨论。首先讨论了影响诊断方法泛化性能的可能因素,然后构建了多个跨数据集诊断任务,在此基础上对几个数据驱动诊断方法的泛化性能进行了经验性的分析,分析发现相较于模型复杂度数据集间的分布差异是影响跨域诊断泛化性能的主要因素;并进一步从信号特性分析的角度解释了设备型号差异和工况差异对跨域诊断性能影响的深层次原因。这些讨论有益于启发面向实际诊断情形的数据驱动诊断方法的研究。

德国语言学会话分析研究综述

德语语言学的会话分析自20世纪70年代兴起之后,在几十年的发展历程中不断扩展自身的研究触角、深化理论建设,成为语言学界蓬勃发展的一支,其研究成果更是倍受多门相关学科关注。本文将从起源、概念以及研究现状等方面介绍德语语言学中有关会话分析研究的情况,以期为我国的会话研究提供有益的借鉴。

Evaluation of group effect of pile group under dragload embedded in clay

A simple semi-empirical analysis method for predicting the group effect of pile group under dragload embedded in clay was described assuming an effective influence area around various locations of pile group. Various pile and soil parameters such as the array of pile group, spacing of the piles (S), embedment length to diameter ratio of piles (L/D) and the soil properties such as density (γ), angle of internal friction (φ) and pile-soil interface friction coefficient (μ) were considered in the analysis. Model test for dragload of pile group on viscosity soil layer under surface load consolidation conditions was studied. The variations of dragload of pile, resistance of pile tip and the layered settlement of soil with consolidation time were measured. In order to perform comparative analysis, single pile was tested in the same conditions. The predicted group effect values of pile group under dragload were then compared with model test results carried out as a part of the present investigation and also with the values reported in literatures. The predicted values were found to be in good agreement with the measured values, validating the developed analysis method. The model test results show that negative skin friction of pile shaft will reach 80%-90% of its maximum value, when pile-soil relative displacement reaches 2 mm.

On the Non-linear Motion of IGS Station

With the daily SINEX files of the IGS, the time series of IGS stations are obtained using an independently developed software under generalized network adjustment models with coordinate patterns. From the time series, non-linear motions are found. With spectral analysis method, the variation frequency （annual period and semi-annual period） of the site velocity is found. Moreover, the empirical model of the velocity variation of the station has been established by regression analysis method based on the weekly solution coordinate series of the station. With respect to the velocity of the IGS tracking station, it was better to model the variation periodically or to give a velocity periodically using a piece-wise linear function rather than a linear variable to estimate its bias.

Multi-scale Chaotic Analysis of the Characteristics of Gas-Liquid Two-phase Flow Patterns

Using the high-speed camera the time sequences of the classical flow patterns of horizontal gas-liquid pipe flow are recorded, from which the average gray-scale values of single-frame images are extracted. Thus obtained gray-scale time series is decomposed by the Empirical Mode Decomposition (EMD) method, the various scales of the signals are processed by Hurst exponent method, and then the dual-fractal characteristics are obtained. The scattered bubble and the bubble cluster theories are applied to the evolution analysis of two-phase flow patterns. At the same time the various signals are checked in the chaotic recursion chart by which the two typical characteristics (diagonal average length and Shannon entropy) are obtained. Resulting term of these properties, the dynamic characteristics of gas-liquid two-phase flow patterns are quantitatively analyzed. The results show that the evolution paths of gas-liquid two-phase flow patterns can be well characterized by the integrated analysis on the basis of the gray-scale time series of flowing images from EMD, Hurst exponents and Recurrence Plot (RP). In the middle frequency section (2nd, 3rd, 4th scales), three flow patterns decomposed by the EMD exhibit dual fractal characteristics which represent the dynamic features of bubble cluster, single bubble, slug bubble and scattered bubble. According to the change of diagonal average lengths and recursive Shannon entropy characteristic value, the structure deterministic of the slug flow is better than the other two patterns. After the decomposition by EMD the slug flow and the mist flow in the high frequency section have obvious peaks. Anyway, it is an effective way to understand and characterize the dynamic characteristics of two-phase flow patterns using the multi-scale non-linear analysis method based on image gray-scale fluctuation signals.

Vibration-based feature extraction of determining dynamic characteristic for engine block low vibration design

In order to maintain vibration performances within the limits of the design, a vibration-based feature extraction method for dynamic characteristic using empirical mode decomposition （EMD） and wavelet analysis was proposed. The proposed method was verified experimentally and numerically by implementing the scheme on engine block. In the implementation process, the following steps were identified to be important： 1） EMD technique in order to solve the feature extraction of vibration signals; 2） Vibration measurement for the purpose of confirming the structural weak regions of engine block in experiment; 3） Finite element modeling for the purpose of determining dynamic characteristic in time region and frequency region to affirm the comparability of response character corresponding to improvement schemes; 4） Adopting a feature index oflMF for structural improvement based on EMD and wavelet analysis. The obtained results show that IMF of signal is more sensitive to response character corresponding to improvement schemes. Finally, examination of the results confirms that the proposed vibration-based feature extraction method is very robust, and focuses on the relative merits of modification and full-scale structural optimization of engine, together with the creation of new low-vibration designs.

Sustainable Development of Export: Theoretical Meaning, Evaluation Model, and Empirical Research

With the effect of the human trade doctrine in the international trade field, almost all the countries have paid more attention to the sustainable development of international trade. This article chose the export sustainable development as the research object. On the basis of the analysis of the theoretical connotation of the export sustainable development, this article tried to establish an evaluation indices system and set up an evaluation model of the export sustainable development level, and finally made some empirical research on China. The result indicates that the comprehensive level of the export sustainable development in China showed a tendency to rise from 1985 to 2003 and the export sustainable development level of China in these years can be divided into four grades: excellent, good, moderate and poor. In most years, the social economic benefits of export was obtained at the cost of the deterioration of environment and the depletion of resources, and the economic profit of export did not increase with the enlargement of the export scale because of the deterioration of the terms of trade. Therefore, China should be careful about the problem of poverty accompanied by the increase of export.

Martian magnetic field properties before the termination of its core dynamo

Observed Martian crustal magnetism shows that the Mars does not possess a global-scale,dynamo-driven intrinsic magnetic field.In addition,the remnant field at the surface is hemi-spherically asymmetric.Our earlier simulation results suggest that the Martian dynamo could be sub-critical near its end(the energy required to sustain a subcritical dynamo is less than that to excite the dynamo)and the generated field morphology is non-dipolar.We further the study to examine the characteristics of the magnetic field via Empirical Orthogonal Function(EOF)analysis on the subcritical dynamo solutions with the Rayleigh number Rth = 2480(below the critical point for the onset of the Martian dynamo).Our results show that the magnetic field is dominantly equatorial dipolar.Reversals and excursions occur frequently,and the magnetic dipole moment does not vary monotonically in time.