菊糖对大鼠钙吸收利用的影响

菊糖是从菊芋中提取的一种水溶性天然多糖,在中性和弱碱性的环境下可提高钙的溶解度和钙溶液的稳定性。取SD大鼠16只,分成对照组和实验组两组,对照组喂予基础饲料;实验组为基础饲料并灌胃2mL菊糖液(150mg/mL),喂养2周,并进行4天钙代谢试验。结果表明:实验组的钙吸收率比对照组提高10·60%,差别有显著性意义,血钙含量无显著差异。     

Experimental study on applicability of using time-domain reflectometry to detect NAPLs contaminated sands

Underground contamination by non-aqueous phase liquids (NAPLs) becomes increasingly serious. Rapid and reliable detection of contaminated zone and degree is the first step to site remediation. In this paper, diesel and fine sand are used as experiment materials to investigate the applicability of using time-domain reflectometry (TDR) to detect LNAPLs contamination. The major work includes: measurement of dielectric constant and electrical conductivity for the diesel-water-air-sand mixtures; measurement of reflection waveform and dielectric constant for specimens with a diesel contaminated layer being sandwiched in sand. The experimental results show the followings: A significant decrease in both dielectric constant and electrical conductivity is observed for the diesel-water-air-sand mixtures when diesel displaces the pore water, and the content of diesel can be calculated by the model; insignificant change in dielectric properties is measured when diesel only displaces the pore gas; when the diesel contaminated sand is sandwiched between two saturated sand layers, the interfaces of the diesel contaminated layer can be identified by analyzing the reflection waveform; for field application, TDR method is valid for the case that LNAPLs seep into saturated sand layer, and the applicability of TDR method in vadose zone depends on the initial saturation of the sand layer. The findings obtained in this paper provide a guidance for the use of TDR for the field investigation of NAPLs contaminated site.     

AOD estimation in WSN localization system with synthetic aperture technique

Angel of departure(AOD) based distributed localization scheme in wireless sensor networks allows the single antenna sensor node to estimate its own AOD information by an equivalent antenna array for further position calculation.However,the condition that the number of antennas at the multi-antenna agent/anchor node should be larger than the number of multipath signal components(MPCs) constrains its actual application.In this paper,we provide a more practical approach to achieve AOD information estimation under multipath environment.Given that the sensor node can not identify the line of sight(LOS) signal component due to the insufficient degree of freedom,which is determined by the above limiting condition,we introduce a synthetic aperture technique with the aid of a fast moving multi-antenna agent/anchor node.This operation greatly enlarges the degree of freedom of the equivalent antenna array constructed at sensor node end but without requiring other extra physical antennas equipped at agent/anchor node or sensor node end,which means that it relaxes the limiting condition.Therefore,the AOD information of LOS signal component can be estimated and extracted successfully in complex multipath environment.Theoretical analysis proves the effectiveness of our proposed synthetic aperture technique and numerical simulations show great performance improvement.     

Quantized innovations Kalman filter: stability and modification with scaling quantization

The stability of quantized innovations Kalman filtering (QIKF) is analyzed. In the analysis, the correlation between quantization errors and measurement noises is considered. By taking the quantization errors as a random perturbation in the observation system, the QIKF for the original system is equivalent to a Kalman-like filtering for the equivalent state-observation system. Thus, the estimate error covariance matrix of QIKF can be more exactly analyzed. The boundedness of the estimate error covariance matrix of QIKF is obtained under some weak conditions. The design of the number of quantized levels is discussed to guarantee the stability of QIKF. To overcome the instability and divergence of QIKF when the number of quantization levels is small, we propose a Kalman filter using scaling quantized innovations. Numerical simulations show the validity of the theorems and algorithms.     

Automatic mass segmentation on mammograms combining random walks and active contour

Accurate mass segmentation on mammograms is a critical step in computer-aided diagnosis (CAD) systems. It is also a challenging task since some of the mass lesions are embedded in normal tissues and possess poor contrast or ambiguous margins. Besides, the shapes and densities of masses in mammograms are various. In this paper, a hybrid method combining a random walks algorithm and Chan-Vese (CV) active contour is proposed for automatic mass segmentation on mammograms. The data set used in this study consists of 1095 mass regions of interest (ROIs). First, the original ROI is preprocessed to suppress noise and surrounding tissues. Based on the preprocessed ROI, a set of seed points is generated for initial random walks segmentation. Afterward, an initial contour of mass and two probability matrices are produced by the initial random walks segmentation. These two probability matrices are used to modify the energy function of the CV model for prevention of contour leaking. Lastly, the final segmentation result is derived by the modified CV model, during which the probability matrices are updated by inserting several rounds of random walks. The proposed method is tested and compared with other four methods. The segmentation results are evaluated based on four evaluation metrics. Experimental results indicate that the proposed method produces more accurate mass segmentation results than the other four methods.     

Global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback

This paper presents both analytical and numerical studies on the global view of Hopf bifurcations of a van der Pol oscillator with delayed state feedback.Based on a detailed analysis of the stability switches of the trivial equilibrium of the system,the stability charts are given in a parameter space consisting of the time delay and the feedback gains.The center manifold reduc-tion and the normal form method are used to study Hopf bifurcations with respect to the time delay.To gain an insight into the persi...     

An analytical solution to contaminant transport through composite liners with geomembrane defects

To investigate the performance of landfill composite liner system,a one-dimensional model was developed for solute transport through composite liners containing geomembrane defects.An analytical solution to the model was obtained by the method of Laplace transformation.The results obtained by the presented solution agree well with those obtained by the numerical method.Results show that leachate head and construction quality of geomembrane(GM) have significant influences on the performance of the composite ...     

Characteristics of dry friction backward whirl—A self-excited oscillation in rotor-to-stator contact systems

In this paper,the response characteristics of dry friction backward whirl of a general rotor/stator model,which accounts for both the dynamics of the rotor and the stator as well as the friction and the deformation at the contact surfaces,are investigated.The existence boundaries and the whirl frequencies of the dry friction backward whirl are determined analytically.It is found that there are two or three existence boundaries of the dry friction backward whirl that usually form two existence regions,either...     

Extraordinary Performances at the Salk Institute for Biological Studies

While the design tactics and systems of the Salk Institute for Biological Studies are well documented, its performance remains less explored. Based upon extended in situ observation, I present an account of the building in terms of its day-to-day performances as well as cumulative evidence of its performance over its forty-year history. Contrary to accounts that focus on the building's extraordinary qualities, this article argues that in the end, it is ordinary details and systems that engender its most consequential performances. Central to this account is an approach that integrates organizational, technical, and aesthetic performance parameters for a polyvalent understanding of performance in architecture.     

移动机器人寻迹算法研究

传统的寻迹算法控制下的移动机器人通过复杂路径时常产生路径识别错误。针对这种情况,首先将移动机器人的寻迹过程抽象成运动学模型,然后将模糊PID算法应用于机器人控制,并针对交叉路径的识别问题提出了改进的寻迹算法。实验证明：采用所述算法后,机器人能正确地识别交叉道,实现了对复杂路径的准确、快速跟踪。