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101.
Chengjun Yao Yixun Liu Jianhua Yao Dongxiao Zhuang Jinsong Wu Zhiyong Qin Ying Mao Liangfu Zhou 《Computer methods and programs in biomedicine》2014
Background
Preoperatively acquired diffusion tensor image (DTI) and blood oxygen level dependent (BOLD) have been proved to be effective in providing more anatomical and functional information; however, the brain deformation induced by brain shift and tumor resection severely impairs the correspondence between the image space and the patient space in image-guided neurosurgery.Method
To address the brain deformation, we developed a hybrid non-rigid registration method to register high-field preoperative MRI with low-field intra-operative MRI in order to recover the deformation induced by brain shift and tumor resection. The registered DTI and BOLD are fused with low-field intra-operative MRI for image-guided neurosurgery.Results
The proposed hybrid registration method was evaluated by comparing the landmarks predicted by the hybrid registration method with the landmarks identified in the low-field intra-operative MRI for 10 patients. The prediction error of the hybrid method is 1.92 ± 0.54 mm, and the compensation accuracy is 74.3 ± 5.0%. Compared to the landmarks far from the resection region, those near the resection region demonstrated a higher compensation accuracy (P-value = .003) although these landmarks had larger initial displacements.Conclusions
The proposed hybrid registration method is able to bring preoperatively acquired BOLD and DTI into the operating room and compensate for the deformation to augment low-field intra-operative MRI with rich anatomical and functional information. 相似文献102.
103.
Qin Zou Yu Cao Qingquan Li Qingzhou Mao Song Wang 《Machine Vision and Applications》2014,25(7):1841-1858
Recent inpainting techniques usually require human interactions which are labor intensive and dependent on the user experiences. In this paper, we introduce an automatic inpainting technique to remove undesired fence-like structures from images. Specifically, the proposed technique works on the RGBD images which have recently become cheaper and easier to obtain using the Microsoft Kinect. The basic idea is to segment and remove the undesired fence-like structures by using both depth and color information, and then adapt an existing inpainting algorithm to fill the holes resulting from the structure removal. We found that it is difficult to achieve a satisfactory segmentation of such structures by only using the depth channel. In this paper, we use the depth information to help identify a set of foreground and background strokes, with which we apply a graph-cut algorithm on the color channels to obtain a more accurate segmentation for inpainting. We demonstrate the effectiveness of the proposed technique by experiments on a set of Kinect images. 相似文献
104.
As an effective approach for multi-input multi-output regression estimation problems, a multi-dimensional support vector regression (SVR), named M-SVR, is generally capable of obtaining better predictions than applying a conventional support vector machine (SVM) independently for each output dimension. However, although there are many generalization error bounds for conventional SVMs, all of them cannot be directly applied to M-SVR. In this paper, a new leave-one-out (LOO) error estimate for M-SVR is derived firstly through a virtual LOO cross-validation procedure. This LOO error estimate can be straightway calculated once a training process ended with less computational complexity than traditional LOO method. Based on this LOO estimate, a new model selection methods for M-SVR based on multi-objective optimization strategy is further proposed in this paper. Experiments on toy noisy function regression and practical engineering data set, that is, dynamic load identification on cylinder vibration system, are both conducted, demonstrating comparable results of the proposed method in terms of generalization performance and computational cost. 相似文献
105.
The solid solution of CaTi1−x
Zr
x
O3 (x = 0–0.15) was successfully synthesized by the polymerized complex (PC) method. This study has exhibited the advantage of
the PC method to prepare a highly active CaTiO3 compared with the conventional solid-state reaction (SSR) method. More importantly, further improvement in phase purity and
large surface area was achieved by the doping of Zr4+, leading to remarkable enhancement of photocatalytic activities compared to pure CaTiO3. The quantum yield for H2 evolution over the most active photocatalyst, Pt (1.0 wt%)/CaTi0.93Zr0.07O3, was 1.91% and 13.3% in photoreactions from pure water and aqueous ethanol solution, respectively for 0.1 g photocatalyst,
which was about 3.3 and 2.5 times compared to that of PC-derived CaTiO3. 相似文献
106.
107.
壁面处湍流速度梯度脉动的测量对于深入了解壁面附近湍流的结构和传热、传质是很重要的.本文叙述了电化学法测量的原理,介绍了用一半圆电极对同时测量壁面上二维湍流速度梯度脉动的方法和测量结果.在直径0.194m的充分发展圆管湍流中,用碘和碘化钾溶液作为流动介质,半圆电极对直径为5×10~-4m,测得壁面处轴向和周向速度梯度的湍流脉动强度分别为0.3—0.33和0.11—0.12. 相似文献
108.
109.
β-spodumene glass–ceramics with a whisker-like microstructure were prepared from the following materials (in wt%): 64.5 SiO2 , 18.0 Al2 O3 , 4.2 Li2 O, 4 ZrO2 , and 8 MgF2 . Scanning electron microscope (SEM) analysis showed that phase separation in the base glass leads to the formation of a primary crystal phase of MgF2 that promotes the formation of spherical β-spodumene. Whisker spodumene crystals surrounded by spherical crystals are observed at 720°C after 1 h, and the whisker crystals grow at the cost of spherical crystals with increasing temperature and time. The flexural strengths of the glass–ceramics reach a maximum of 228 MPa after heat treatment at 850°C for 1 h. 相似文献
110.
Vinnie?Mao Samir?K.?Konar David?G.?B.?BoocockEmail author 《Journal of the American Oil Chemists' Society》2004,81(8):803-808
The base-catalyzed transmethylation of soybean oil has been studied under conditions whereby the reaction starts as a single
phase, but later becomes two phases as glycerol separates. Methanol/oil molar ratios of 6∶1 were used at 23°C. The catalysts
were sodium hydroxide (0.5, 1.0, and 2.0 wt%), potassium hydroxide (1.0 and 1.4 wt%), and sodium methoxide (0.5, 1.0, and
1.35 wt%), all concentrations being with respect to the oil. Oxolane (tetrahydrofuran) was used to form a single reaction
phase. The reactions deviated from homogeneous kinetics as glycerol separated, taking with it most of the catalyst. When 1.0
wt% sodium hydroxide was used, the methyl ester content reached 97.5 wt% after 4 h, compared with 85–90 wt% in the two-phase
reaction. Sodium hydroxide (1.0 wt%), sodium methoxide (1.35 wt%), and potassium hydroxide (1.4 wt%) gave similar results,
presumably because the same number of moles was used. The ASTM biodiesel specification for chemically bound glycerol was achieved
after only 3 min when 2.0 wt% sodium hydroxide was used. However, the standard was not achieved after 4 h when 1.0 wt% sodium
hydroxide was used, the MG content being 1.1–1.6 wt%. The use of 2.0 wt% catalyst is commercially impractical. 相似文献