漫反射参照体双向反射比因子绝对测量研究

为提高漫反射参照体双向反射比因子(BRF)测量准确度,设计了漫反射参照体BRF绝对测量系统。该系统以积分球辐射源为照明光源,高精度陷阱(Trap)辐亮度计为探测器,通过对积分球辐射源辐亮度、漫反射参照体反射辐亮度和几何因子的测量,实现了漫反射参照体BRF绝对测量。结果分析表明,测量不确定度优于1%(k=2),通过对630 nm波长下漫反射参照体BRF数值积分得到的方向-半球反射比因子(DHRF)比溯源到中国计量科学研究院的采用积分球方法得到的DHRF高0.57%,差别在二者测量不确定度范围之内,进而验证了BRF绝对测量的准确性。

标准漫反射板绝对反射比因子测量装置

分析和研究了测量绝对反射比因子的原理,设计、制作了一套可以测量光源入射照度和反射辐亮度的比辐射计和一套45°/0°漫反射板绝对反射比因子测量装置。首先,使用比辐射计测量光源的入射照度和反射辐亮度,给出漫反射板绝对反射比因子的计算公式;然后,根据推导公式中辐射亮度由测量比辐射计的光阑面积决定,提出一种新的光学方法来精确测量光阑面积,从而提高测量精度。最后,介绍了测量装置的设计和其它部件的制作过程。采用该装置实验测量了安徽光学精密机械研究所研制的标准漫反射板在633～960nm的绝对反射比因子,得到的装置的测量不确定度为0.19%。实验结果表明,该测量装置测量方法简单、精度高,可以满足反射比因子的测量要求。

基于因子模型的商品房住宅价格机制研究

本文根据中国四个一线城市商品房住宅市场2007年至2017年不同小区不同户型住宅的月度房价和房租的数据样本,着重研究了一线城市住宅的投资收益率性质。研究发现,住宅的月度收益率存在显著的价值效应,户型效应,中短期动量效应,以及长期反转效应。基于这些发现,本研究提出了包含市场因子,房价房租比因子,以及动量因子在内,用以解释我国住宅房地产收益率的三因子模型。实证结果显示,本文提出的三因子模型能够很好地解释商品房住宅市场上不同类型住宅的收益率,加深学术界和政策界对于商品房住宅市场中价格形成机制的理解。本文的研究成果对于帮助政府灵活施策,更加有效调控房地产市场具有积极参考意义。

基于烟花算法的可见光通信光源功率优化方法

为了改善室内可见光通信系统接收平面光信号信噪比波动大的问题,提高可见光通信系统的整体性能,设计了基于群体优化算法——烟花算法的可见光通信系统的光源功率优化算法.该算法以无线光接收平面的信噪比因子为优化目标,优化每个LED(Light Emitting Diode)光源的发射功率,获取接收平面最优信噪比因子,有效降低光接收平面光信号波动度.结果表明,当光源数量为16个点光源时,接收平面信噪比因子比等功率的光源分布降低了45%,显著改善了接收光信号的波动幅度,从而保证不同位置点的光通信用户获得同等通信质量.该方法适用于任意数量和位置的LED光源,不受光源数量和位置的限制.对比分析发现,增加光源数量,接收平面信噪比因子更小,信噪比分布均匀性更优.

基于AHP和排序比的高校本科教学质量评价方法

分析高校二级学院教学质量综合评价方法问题,提出利用AHP层次分析方法,构建高校本科教学质量指标体系层次模型,计算量化的权重,并设计综合考虑指标权重和指标值相对优势的评价模型,最后说明方法实现和应用情况。

如何规划和建设具有更加节能环保特性的数据中心

为了降低IDC机房的能耗比(PUE值),系统地分析了三种可利用室外自然冷源的空调系统及三种UPS供电系统的能耗比因子。在此基础上,可设计出PUE<1.5的IDC机房,同PUE=2～2.4的传统IDC机房相比,其节能降耗效果显著。

不同灰阶参考极实验室双向反射比定标的研究

通过大量实验数据处理分析，给出了不同灰阶参考板的双向反射比因子随角度变化的特性，并阐明了参考板在野外太阳入射角不断变化条件下使用，双向反射比的校正显得非常必要。

基于本征模态函数最优配比的冲击波信号经验模态分解降噪方法

将原始信号进行EMD分解,通过系统校准和遍历寻优求得各个IMF的最优配比因子,将其重构后得到降噪信号。扫频信号仿真实验,结果去除了系统噪声,且对信号高频分量保留完好。爆炸冲击波实测实验,降噪结果有效去除噪声,且较好地保留冲击波前沿高频分量。在峰值压力、正压作用时间和冲量3个方面与原始信号偏差仅为-4.91%、1.06%和2.12%,优于小波降噪结果。

Tomographic inversion of near-surface Q factor by combining surface and cross-hole seismic surveys

The estimation of the quality factor Q plays a fundamental role in enhancing seismic resolution via absorption compensation in the near-surface layer.We present a new geometry that can be used to acquire field data by combining surface and cross-hole surveys to decrease the effect of geophone coupling on Q estimation.In this study,we drilled number of receiver holes around the source hole,each hole has different depth and each geophone is placed geophones into the bottom of each receiver hole to avoid the effect of geophone coupling with the borehole wall on Q estimation in conventional cross-hole seismic surveys.We also propose a novel tomographic inversion of the Q factor without the effect of the source signature,and examine its stability and reliability using synthetic data.We estimate the Q factors of the near-surface layer in two different frequency bands using field data acquired in the Dagang Oilfield.The results show that seismic absorption in the nearsurface layer is much greater than that in the subsurface strata.Thus,it is of critical practical importance to enhance the seismic solution by compensating for near-surface absorption.In addition,we derive different Q factors from two frequency bands,which can be treated,to some extent,as evidence of a frequency-dependent Q.

房地产限购政策对存量房价格的影响研究——基于北京市场的经验证据

房地产是一种具有消费和投资双重属性的特殊商品,其价格不仅受到市场供需的影响,也受政府调控的影响。政府可以通过限购政策调节市场需求端来影响房价。文章借鉴事件研究法,以限购政策实施后三个月为政策窗口期,构造了一个投机占比因子再进行了回归分析。结果表明在政策窗口期内,投机交易数量多的小区拥有更高每平米累计收益率,投机活动显著地影响存量房价格。因此房地产限购政策会通过影响投机需求来刺激或者抑制房价。此外限购政策在短期内是有效的,但是从长期来看效果有限,而国家战略布局则会对相关房地产市场产生长远影响。

材料光学性能测试与设备

TB96 2000010594不同灰阶参考板实验室双向反射比定标的研究=Study of bidirectional reflectance calibrationbased on varied grey scale panels[刊,中]/王先华,张黎明,乔延利,章骏平,李健康(中科院安徽光机所.安徽,合肥(230031))//光电子技术与信息.—1998,11(5).—10-15通过大量实验数据处理分析,给出了不同灰阶参考板的双向反射比因子随角度变化的特性,并阐明了参考板在野外太阳入射角不断变化条件下使用,双向反射比的校正非常重要。图7参4(严寒)TB96 2000010595群速失配在二次谐波自相关法中的影响:Ⅰ类及Ⅱ类相位匹配=Effect of group velocity mismatch

货币政策对存量房价格的影响研究——来自北京市场的经验证据

房地产是具有消费和投资双重属性的特殊商品,其价格不仅受到市场供需的影响,也受政府调控的影响。而货币政策是政府调控的重要手段之一,可以通过影响市场需求来调节房价。文章借鉴事件研究法,以货币政策调整后三个月为政策窗口期,构造了一个投机占比因子后再进行回归分析。结果表明,在政策窗口期内,投机交易数量多的小区拥有更高的每平米累计收益率,投机活动显著地影响房价。因此,当货币政策发生变动时,会通过影响投机需求进而刺激或者抑制房价。

Integrated interpretation of dual frequency induced polarization measurement based on wavelet analysis and metal factor methods

In mineral exploration, the apparent resistivity and apparent frequency （or apparent polarizability） parameters of induced polarization method are commonly utilized to describe the induced polarization anomaly. When the target geology structure is significantly complicated, these parameters would fail to reflect the nature of the anomaly source, and wrong conclusions may be obtained. A wavelet approach and a metal factor method were used to comprehensively interpret the induced polarization anomaly of complex geologic bodies in the Adi Bladia mine. Db5 wavelet basis was used to conduct two-scale decomposition and reconstruction, which effectively suppress the noise interference of greenschist facies regional metamorphism and magma intrusion, making energy concentrated and boundary problem unobservable. On the basis of that, the ore-induced anomaly was effectively extracted by the metal factor method.

STUDY ON CRACKED PLATES WITH BONDED PATCHES UNDER IN PLANE BIAXIAL LOADINGS

Based on the finite element method, a numerical investigation into the bonded repair efficiency of cracked plates under in plane biaxial loadings is presented. The main considerations are: reduction in stress intensity factor (SIF) at the crack tip, the maximum tensile stress in the composite patch and the maximum shear stress in the adhesive bond between the patch and the plate. Without the patch, a tensile or compressive stress parallel to the crack has no effect on the SIF at the crack tip. While with a composite patch, there exists coupling effect between the normal stress parallel to the crack and the SIF, and the coupling effect depends significantly on ply orientation of the patch and the biaxial stress ratio of the plate.

Estimation of quality factors by energy ratio method

The quality factor Q, which reflects the energy attenuation of seismic waves in subsurface media, is a diagnostic tool for hydrocarbon detection and reservoir characterization. In this paper, we propose a new Q extraction method based on the energy ratio before and after the wavelet attenuation, named the energy-ratio method（ERM）. The proposed method uses multipoint signal data in the time domain to estimate the wavelet energy without invoking the source wavelet spectrum, which is necessary in conventional Q extraction methods, and is applicable to any source wavelet spectrum; however, it requires high-precision seismic data. Forward zero-offset VSP modeling suggests that the ERM can be used for reliable Q inversion after nonintrinsic attenuation（geometric dispersion, refl ection, and transmission loss） compensation. The application to real zero-offset VSP data shows that the Q values extracted by the ERM and spectral ratio methods are identical, which proves the reliability of the new method.

IMPROVED FXLMS ALGORITHM BASED ON ADAPTIVE NOTCH FILTER APPROACH

An improved algorithm is presented to identify the secondary path based on the adaptive notch filter approach. Since the interference from the narrow band excitation signal is suppressed by the adaptive notch filter, the convergent speed of the on-line control path identification process is significantly improved. As a result, the controller performance is greatly enhanced. Besides the algorithm development, some important factors, such as the influence of reference signal on the controller convergent speed, are also discussed. The effectiveness of the algorithm is verified by experimental results.

Acoustic impedance inversion of zero-offset VSP data

Highly precise acoustic impedance inversion is a key technology for pre-drilling prediction by VSP data. In this paper, based on the facts that VSP data has high resolution, high signal to noise ratio, and the downgoing and upgoing waves can be accurately separated, we propose a method of predicting the impedance below the borehole in front of the bit using VSP data. First, the method of nonlinear iterative inversion is adopted to invert for impedance using the VSP corridor stack. Then, by modifying the damping factor in the iteration and using the preconditioned conjugate gradient method to solve the equations, the stability and convergence of the inversion results can be enhanced. The results of theoretical models and actual data demonstrate that the method is effective for pre-drilling prediction using VSP data.

Modified Projective Synchronization of a New Hyperchaotic System via Nonlinear Control

In this paper, a nonlinear control scheme of two identical hyperchaotic Chert systems is developed to realize their modified projective synchronization. We achieve modified projective synchronization between the two identical hyperchaotic systems by directing the scaling factor onto the desired value. With symbolic computation system Maple and Lyapunov stability theory, numerical simulations are given to perform the process of the synchronization.

Differences in characteristics of patients with and without known risk factors for hepatocellular carcinoma in the United States

AIM： To examine the clinical characteristics of a subgroup of patients with hepatocellular carcinoma （HCC） and compare them to those with known risk factors. METHODS： We used the HCC database of 306 patients seen at our institution from January 1, 1995 to December 31, 2001. Of the 306 patients, 63 （20%, group 1） had no known risk factors （hepatitis C virus, hepatitis B virus, alcohol, hemochromatosis or cirrhosis from any cause） and 243 （group 2） had one or more risk factors. RESULTS： The median age was similar in both groups, but there were disproportionate numbers of younger （〈 30 years old）, older （〉 80 years） patients, women （33% vs 18%）, and Caucasians （81% vs 52%） in group 1 as compared to group 2. There were fewer Asians （2% vs 11%） and African Americans （13% vs 27%） in group 1. Abdominal pain （70% vs 37%） was more common while gastrointestinal bleeding （0% vs 11%） and ascites （4% vs17%） were less common in group i compared to group 2. Group 1 had larger tumor burden （median size 9.4 cm vs 5.7 cm） at the time of presentation, but there were no differences in the site （right, left or bilateral lesions）, or number of tumors between the two groups. CONCLUSION： HCC patients without identifiable risk factors have different characteristics and clinical presentation compared to those with known risk factors.Absence of cirrhosis and larger tumor burden may explain the differences in the presenting symptoms.