“图层方法”在初中区域地理教学中的应用策略

图层方法主要是指借助地理信息系统的图层概念以及技术来展开地理教学。相较于其他教学方式而言,它具有形象、直观和可操作性强等特征,所以经常被应用于区域地理教学中。本文就“图层方法”在初中区域地理教学中的应用策略进行了探讨,从“图层方法”的应用步骤出发详细说明了问题情境的设置和图层的顺次构建,并对“图层方法”在初中区域地理教学中的应用提出了自己的见解,以期为相关研究者提供参考。

Abnormal cortical functional connections in Alzheimer’s disease: analysis of inter-and intra-hemispheric EEG coherence

To investigate inter- and intra-hemispheric electroencephalography (EEG) coherence at rest and during photic stimulation of patients with Alzheimer's disease (AD). Thirty-five patients (12 males, 23 females; 52～64 y) and 33 sex- and age-matched controls (12 males, 21 females; 56～65 y) were recruited in the present study. EEG signals from C3-C4, P3-P4, T5-T6and O1-O2 electrode pairs resulted from the inter-hemispheric action, and EEG signals from C3-P3, C4-P4, P3-O1, P4-O2, C3-O1,C4-O2, T5-O 1 and T6-O2 electrode pairs resulted from the intra-hemispheric action. The influence of inter- and intra-hemispheric coherence on EEG activity with eyes closed was examined, using fast Fourier transformation from the 16 sampled channels. The frequencies of photic stimulation were fixed at 5, 10 and 15 Hz, respectively. The general decrease of AD patients in inter- and intra-hemispheric EEG coherence was more significant than that of the normal controls at the resting EEG, with most striking decrease observed in the alpha-1 (8.0-9.0 Hz) and alpha-2 (9.5-12.5 Hz) bands. During photic stimulation, inter- and intra-hemispheric EEG coherences of the AD patients having lower values in the alpha (9.5-10.5 Hz) band than those of the control group. It suggests that under stimulated and non-stimulated conditions, AD patients had impaired inter- and intra-hemispheric functional connections, indicating failure of brain activation in alpha-related frequency.

Lamb Wave Arrival Time Extraction Using Hilbert-Huang Transform for Improved Tomography Image

Travel time Lamb wave tomography has been shown to be an effective nondestructive evaluation （NDE） technique for plate-like structures. The methods used previously to extract arrival times of the fastest or multi Lamb wave modes are mostly based on various timefrequency methods such as Wigner-Ville distribution, shorttime Fourier transform, and recently explored wavelet transform（WT）. Frankly speaking, uses of these signal processing methods improve the accuracy of the arrival time extraction to a great extent relative to directly extract arrival times in time-domain from Lamb waveforms. Hilbert-Huang transform（HHT） is also an efficient way for analyzing and processing non-stationary signals. The resolving power of time and frequency is restricted from Heisenberg principle in wavelet analysis, while in HHT, the time resolving power is precise and steady, and frequency resolving power is adaptive according to signal intrinsic characteristics. Conclusion can be made that the HI-IT method is more adaptive than WT anal;/sis in ~.!~M~ zing non-stationary signals. Based on the abo~, ~tiaf method is attempted to extract arrival times from Lamb waveforms in this paper. The Lamb wave tomography images generated with arrival times from HHT method were compared with those of WT. The results show that the new method improves the quality of tomography image, which demonstrates the applicability of HHT method in extracting arrival times of Lamb waves.

Computed Tomography Using Level Set Method and Algebraic Reconstruction Technique

In this paper, a novel reconstruction technique based on level set method and algebraic reconstruction technique is proposed for multiphase flow computed tomography (CT) system. The curvature-driven noise reduction method is inserted into the conventional iteration procedure of algebraic reconstruction technique to improve the image quality and convergence speed with limited projection data. By evolving the image as a set of iso-intensity contours after each updation, the sufficient number of iterations for acceptable results is reduced by 80%-90%, while the image quality is enhanced obviously. Quantitative evaluation of image quality is given by using both relative image error and correlation coefficient. The resultant images can be utilized to detect flow regimes for monitoring industrial multiphase flow. Laboratory results demonstrate the feasibility of the proposed method. Phantoms of four typical flow regimes can be reconstructed from few-view projection data efficiently, and the corresponding image errors and correlation coefficients are acceptable for the cases tested in this paper.

Digital Image Processing Methods for Bridge Coating Management and Their Limitations

Accurate and objective rust defect assessment is required to maintain good quality steel bridge coating surfaces and make a decision whether a bridge shall completely or partially be repainted. For more objective rust defect recognition, digital image recognition methods have been developed for the past few years and they are expected to replace or complement conventional painting inspection methods. Efficient image processing methods are also essential for the successful implementation of steel bridge coating warranty contracting where the owner, usually a state agency, and the contractor inspect steel bridge coating conditions regularly and decide whether additional maintenance actions are needed based on the processed data. There are two approaches to develop automated rust defect recognition methods： applying a statistical method or an artificial intelligence technique. This paper presents the application of previously developed image processing methods for defect evaluations on a bridge coating surface and discusses their limitations under three environmental conditions which are often encountered while acquiring digital images.

Infrared thermography display of cortical temperature in cats

OBJECTIVE: To use infrared thermography to take cat cerebral cortical temperature in order to visualize the temperature of its entire cerebral cortex as an image. METHODS: After performing craniotomy for exposure of cerebral hemispheres in 52 cats, their cortical temperatures were displayed and analyzed by computerized infrared thermovision. RESULTS: The temperature distribution of the cerebral cortex was uneven, with a maximum difference of 2.3 degrees C among different cortical areas. The temperature in the cortical anterior-inferior area (including the Ant. Ectosylvian, the lower section of Mid. Ectosylvian and the Ant. Sylvian) was higher compared to the temperature in the posterior-super-parts (Post. Suprasylvian, Mid. Suprasylvian, Post. Lateral and Ant. Lateral). Locations with higher or lower temperatures showed little change within three days after craniotomy, and the cortical temperature held steady. CONCLUSION: The use of cortical infrared thermo-images for display of cat cortical temperature is possible and has many advantages over traditional methods. This new neuroimaging method has a practical value in neurological research.