试论图形在课堂教学中的作用

本文通过五个图例,说明图解法、图示法和图证法在数学分析课堂教学中的独特作用。笔者坚信:利用图形改革教学在数学的其他学科,甚至在其他专业的教学中,都具有一定的重要意义。

Accuracy Validation for Medical Image Registration Algorithms:a Review

Accuracy validation is essential to clinical application of medical image registration techniques. Registration validation remains a challenging problem in practice mainly due to lack of 'ground truth'. In this paper, an overview of current validation methods for medical image registration is presented with detailed discussion of their benefits and drawbacks. Special focus is on non-rigid registration validation. Promising solution is also discussed.

The Modals as Pragmatic Softening Devices： Evidence From Late Modern English Grammar and Manner Books

In this research, the author considers the evidence provided by a corpus of Late Modem English grammars for our understanding of the development of the modals as politeness markers. It is possible to see how the modals and their accompanied senses are explained in an official （and often either prescriptive or proscriptive） perspective. This is another aspect which cannot be ascertained from the usage based on corpora which seem to be popular as sources of evidence in historical pragmatics. In this sense, this research brings some novel perspective to this aspect of academic study. It is possible to notice that the significations involves concept or senses which extend across a semantic--pragmatic domain which includes politeness. We can see that certain softening senses are key elements to mark polite usage. The main data used come from the descriptions of the modal auxiliary verb in a corpus of grammar books from the period. Usage and manner books are also consulted as a secondary resource. The manner book in particular is quite helpful for our understanding of how linguistic politeness was regarded at the time. Such texts also help us to find a certain network of senses which are related to polite expressions.

Fusion of ERT Images Based on Dempster-Shafer's Evidence Theory

In this paper, an electrical resistance tomography(ERT) imaging method is used as a classifier, and then the Dempster-Shafer's evidence theory with fuzzy clustering is integrated to improve the ERT image quality. The fuzzy clustering is applied to determining the key mass function, and dealing with the uncertain, incomplete and inconsistent measured imaging data in ERT. The proposed method was applied to images with the same investigated object under eight typical current drive patterns. Experiments were performed on a group of simulations using COMSOL Multiphysics tool and measurements with a piece of porcine lung and a pair of porcine kidneys as test materials. Compared with any single drive pattern, the proposed method can provide images with a spatial resolution of about 10% higher, while the time resolution was almost the same.

A multiple watermarks algorithm for image content authentication

A novel multiple watermarks cooperative authentication algorithm was presented for image contents authentication.This algorithm is able to extract multiple features from the image wavelet domain,which is based on that the t watermarks are generated.Moreover,a new watermark embedding method,using the space geometric model,was proposed,in order to effectively tackle with the mutual influences problem among t watermarks.Specifically,the incidental tampering location,the classification of intentional content tampering and the incidental modification can be achieved via mutual cooperation of the t watermarks.Both the theoretical analysis and simulations results validate the feasibility and efficacy of the proposed algorithm.

DTCWT-based zinc fast roughing working condition identification

The surface texture of mineral flotation froth is well acknowledged as an important index of the flotation process.The surface texture feature closely relates to the flotation working conditions and hence can be used as a visual indicator for the zinc fast roughing working condition. A novel working condition identification method based on the dual-tree complex wavelet transform(DTCWT) is proposed for process monitoring of zinc fast roughing.Three-level DTCWT is implemented to decompose the froth image into different directions and resolutions in advance, and then the energy parameter of each sub-image is extracted as the froth texture feature. Then, an improved random forest integrated classification(i RFIC) with 10-fold cross-validation model is introduced as the classifier to identify the roughing working condition, which effectively improves the shortcomings of the single model and overcomes the characteristic redundancy but achieves higher generalization performance. Extensive experiments have verified the effectiveness of the proposed method.

Determination of residual stress distribution combining slot milling method and finite element approach

Residual stress plays a vital role in the structural strength and stability. The determination of residual stress at single-point has become mature at present. However, the method to determine residual stress distribution is still in shortage. For this problem, a finite element approach combined with slot milling method was developed in this study. In the method, firstly a slot is milled on the specimen surface to release the residual stress and then the released displacement field is measured by optical method, such as digital image correlation （DIC）, finally the finite element approach is used to determine the residual stress distribution along the slot. In order to verify the feasibility of the method, it was applied to study the residual stress introduced by shot peening, mainly about the stress distribution along the direction vertical to the shot peened surface. Since the influence depth of shot peening was too small, we utilized focused ion beam （FIB） to determine the microscale residual stress distribution. The result measured by X-ray diffraction （XRD） demonstrated that the method was feasible to determine the residual stress distribution.

A Semi-Fragile Wavelet Transform Watermarking Scheme for Content Authentication of Images

A novel semi-fragile watermarking scheme for the content authentication of images using wavelet transform(WT) is presented in this paper.It is tolerant to the embedded wavelet image compression methods based on WT such as embedded zerotree wavelet(EZW) ,set partitioning in hierarchical trees(SPIHT) and embedded block coding with optimized truncation(EBCOT) in JPEG2000 to a pre-determined bit-plane,but is sensitive to all other malicious attacks.The image features are generated from the lowest-frequency(LF) subband of the original image as the embedded watermark.The watermark is embedded into the pre-determined bit-plane by adjusting the corresponding values in the given subband.In the process of watermarking authentication,we compare the image features generated from the LF subband of the received image with the embedded watermarking information(the image features of the original image) extracted from the pre-determined bit-plane in the given subband of the received image to decide whether the image is attacked maliciously or processed acceptably(the embedded wavelet compression) .The most important advantage of our watermarking scheme is that the watermark information can be extracted from the watermarked image when detecting watermark,so the received image authentication needs no information about the original image or watermark.Experimental results prove the effectiveness of our proposed watermarking scheme.