A nonlinear contact algorithm predicting facet joint contribution in the lumbar spine of a specific person

The objective of this study was to realistically include the effect of facet loading in an EMG-assisted lumbar biomechanical model. Most biomechanical models lack detailed facet geometry, the inclusion of cartilage, and fail to model the full lumbar spine. Several new facet-specific components were added to an EMG-assisted biomechanical model, including realistic geometry and facet-specific contact algorithms. These algorithms defined nonlinear contact between each lumbar spine facet. Subject-specific data were applied to the model for assessment. As expected, resultant disc loads were generally lower in the model with facets. This information improves our understanding of how loads are distributed in the spine, and it can lead to a better understanding of causal pathways. If we understand those pathways, we then realise how to design better ergonomic interventions.     

Bone segmentation and 3D visualization of CT images for traumatic pelvic injuries

Pelvic bone segmentation is a vital step in analyzing pelvic CT images, which assists physicians with diagnostic decision making in cases of traumatic pelvic injuries. Due to the limited resolution of the original CT images and the complexity of pelvic structures and their possible fractures, automatic pelvic bone segmentation in multiple CT slices is very difficult. In this study, an automatic pelvic bone segmentation approach is proposed using the combination of anatomical knowledge and computational techniques. It is developed for solving the problem of accurate and efficient bone segmentation using multiple consecutive pelvic CT slices obtained from each patient. Our proposed segmentation method is able to handle variation of bone shapes between slices there by making it less susceptible to inter‐personal variability between different patients' data. Moreover, the designed training models are validated using a cross‐validation process to demonstrate the effectiveness. The algorithm's capability is tested on a set of 20 CT data sets. Successful segmentation results and quantitative evaluations are present to demonstrate the effectiveness and robustness of proposed algorithm, well suited for pelvic bone segmentation purposes.     

Multiatlas‐based segmentation of female pelvic organs: Application for computer‐aided diagnosis of cervical cancer

Atlas‐based segmentation is a high level segmentation technique which has become a standard paradigm for exploiting prior knowledge in image segmentation. Recent multiatlas‐based methods have provided greatly accurate segmentations of different parts of the human body by propagating manual delineations from multiple atlases in a data set to a query subject and fusing them. The female pelvic region is known to be of high variability which makes the segmentation task difficult. We propose, here, an approach for the segmentation of magnetic resonance imaging (MRI) called multiatlas‐based segmentation using online machine learning (OML). The proposed approach allows separating regions which may be affected by cervical cancer in a female pelvic MRI. The suggested approach is based on an online learning method for the construction of the dataset of atlases. The experiments demonstrate the higher accuracy of the suggested approach compared to a segmentation technique based on a fixed dataset of atlases and single‐atlas‐based segmentation technique.     

A biomechanical investigation of forces applied to the lift truck steering wheel: effects of posture,gender and hand contact on cumulative low back loading

Hand contact forces on a typical lift truck steering wheel were quantified in a laboratory to determine their effects on low back loading. A single muscle equivalent link segment model (3D Match) was used to estimate cumulative loading exposure variables at the L4/L5 intervertebral disc with and without hand contact forces. Hand contact forces significantly decreased cumulative L4/L5 compression in forward bending (FB) for males by 32% and females by 14%. Cumulative L4/L5 compression in males (37,023?±?2183?Ns) was not different from that in females (38,413?±?2224?Ns). When excluding hand contact forces, males had significantly greater cumulative L4/L5 compression (55,165?±?1593?Ns) in FB compared to females (43,255?±?1753?Ns). Hand contact forces on mobile equipment controls might result in decreased cumulative L4/L5 compression, especially in awkward trunk postures. Females may be further predisposed to injury resulting from exposure to cumulative load.     

新型立体式网状宫内节育器初步临床观察

为了观察新型立体式网状宫内节育器(3-DR-IUD)的避孕效果及副反应,将152例志愿受试者随机分为两组,即接受3-DR-IUD组和放置元宫药铜宫内节育器(2-D-IUD)组,每组各76例,常规放置3-DR-IUD和2-D-IUD。分别于术后1个月、3个月、6个月和12个月进行随访,了解放置宫内节育器(IUD)后副反应(如腹痛、腰痛、阴道出血持续时间及出血量、白带等)的发生率、带器妊娠率、IUD脱落率、因症取出率、续用率及避孕效果,并利用B超、X光腹部平片检查3-DR-IUD位置等。两组各76例均成功放置了IUD,术中均无明显疼痛。3-DR-IUD组术后出现白带增多、月经期延长、不规则出血、月经量增多及腰腹部疼痛等副反应6例(7.9%),而2-D-IUD组出现31例(40.8%),两组比较差异有统计学意义(P0.0001)。3-DR-IUD组无脱落,无带器妊娠者,3个月时因对硅橡胶过敏取出1例,12个月时终止率为1.3%,续用率为98.7%(75/76);2-DIUD组终止率为13.2%,续用率为86.8%(66/76),两组比较差异有统计学意义(P=0.009)。实验结果表明,3-DR-IUD具有很好的避孕效果,术后副反应轻微,可为育龄妇女提供新的、安全、高效的IUD。     

Multi-Scale 3D U-Nets: An approach to automatic segmentation of brain tumor

Gliomas segmentation is a critical and challenging task in surgery and treatment, and it is also the basis for subsequent evaluation of gliomas. Magnetic resonance imaging is extensively employed in diagnosing brain and nervous system abnormalities. However, brain tumor segmentation remains a challenging task, because differentiating brain tumors from normal tissues is difficult, tumor boundaries are often ambiguous and there is a high degree of variability in the shape, location, and extent of the patient. It is therefore desired to devise effective image segmentation architectures. In the past few decades, many algorithms for automatic segmentation of brain tumors have been proposed. Methods based on deep learning have achieved favorable performance for brain tumor segmentation. In this article, we propose a Multi-Scale 3D U-Nets architecture, which uses several U-net blocks to capture long-distance spatial information at different resolutions. We upsample feature maps at different resolutions to extract and utilize sufficient features, and we hypothesize that semantically similar features are easier to learn and process. In order to reduce the computational cost, we use 3D depthwise separable convolution instead of some standard 3D convolution. On BraTS 2015 testing set, we obtained dice scores of 0.85, 0.72, and 0.61 for the whole tumor, tumor core, and enhancing tumor, respectively. Our segmentation performance was competitive compared to other state-of-the-art methods.     

Alpha-Shapes分段改进算法在三维模拟树枝体积扫描测量中的应用

针对树木与树枝分叉部分体积计算困难,三维扫描建模易产生黏连现象等问题,提出一种Alpha-Shapes分段改进算法.通过三维激光扫描技术获取三维模拟树枝的点云数据,利用Alpha-Shapes算法计算出三维模拟树枝的点云边缘轮廓并进行三维重建,利用分段算法对三维重建数据进行体积分割计算,通过点云最高层补偿以此保证分段算...     

Fuzzy generalized fast marching method for 3D segmentation of brain structures

The aim of this work is to develop a new model for segmentation of brain structures in medical brain MR images. Brain segmentation is a challenging task due to the complex anatomical structure of brain structures as well as intensity nonuniformity, partial volume effects and noise. Generally the structures of interest are of relatively complicated size and have significant shape variations, the structures boundaries may be blurry or even missing, and the surrounding background is full of irrelevant edges. Segmentation methods based on fuzzy models have been developed to overcome the uncertainty caused by these effects. In this study, we propose a robust and accurate brain structures segmentation method based on a combination of fuzzy model and deformable model. Our method breaks up into two great parts. Initially, a preliminary stage allows to construct the various information maps, in particular a fuzzy map, used as a principal information source, constructed using the Fuzzy C‐means method (FCM). Then, a deformable model implemented with the generalized fast marching method (GFMM), evolves toward the structure to be segmented, under the action of a normal force defined from these information maps. In this sense, we used a powerful evolution function based on a fuzzy model, adapted for brain structures. Two extensions of our general method are presented in this work. The first extension concerns the addition of an edge map to the fuzzy model and the use of some rules adapted to the segmentation process. The second extension consists of the use of several models evolving simultaneously to segment several structures. Extensive experiments are conducted on both simulated and real brain MRI datasets. Our proposed approach shows promising and achieves significant improvements with respect to several state‐of‐the‐art methods and with the three practical segmentation techniques widely used in neuroimaging studies, namely SPM, FSL, and Freesurfer.     

Computational techniques and validation of 3-dimensional viscous/turbulent codes for internal flows

Computational techniques and codes developed for the prediction of three-dimensional turbulent flows in internal configurations and rotor passages are described. Detailed calibration and validation of the flow fields in 90° curved ducts, cascades, end-wall flows and turbomachinery rotors are presented. Interpretation and comments on accuracy, level of agreement with various turbulence models and limitations of the codes are described. The single pass space-marching code is found to be efficient for curved duct and two-dimensional cascade flows. Multipass space-marching, time-marching and zonal methods are found to be accurate for complex situations. The efficiency and accuracy of a zonal technique, with considerable saving in computational time, is demonstrated. Paper presented atagard Symposium “Validation of Computational Fluid Dynamics,” May 2–5, 1988, Lisbon, Portugal The research work on computation was sponsored by the David Taylor Naval Ship Research and Development Center with Dr D Fuhs as the technical monitor, and NASA Lewis Research Center with Dr P Sockol as the technical monitor.     

结合显著性的GrabCut及在骨髓细胞图像分割中的应用

针对传统GrabCut算法需要用户交互缺点,提出一种基于上下文感知显著性的GrabCut的改进的图像分割算法.首先用上下文感知得到待分割图像的显著图,然后由二值化的显著图确定GrabCut算法的初始化区域,再通过迭代使能量函数最小化分割出目标,算法应用于骨髓细胞图像分割上.实验结果表明,此算法能避免以往细胞分割算法如支持向量机、K-Means等参数调整问题,总体误差率较低,自动化程度高,鲁棒性强.     

A variational level set segmentation formulation based on signal model for images in the presence of intensity inhomogeneity

Biological images with significant intensity inhomogeneity are considerably difficult for the tissue segmentation. To overcome the difficulties caused by the intensity inhomogeneity, this study presents a variational level set method to simultaneous bias field estimation and tissue segmentation for images in the presence of intensity inhomogeneity. An energy function is defined in terms of two data fitting terms which incorporate the local clustering properties into the global region information. First, depended on the observed image mode, the local cluster property based on the observed signal is simplified to a criterion function which is similar to the Mumford‐Shah model. The local criterion energy is then integrated with a global region measure, which is based on intensity difference of the true signal. The energy is minimized in a variational level set formulation with a regularity term, thus avoiding the expensive computation of the level set reinitialization and keeping the curve close to the signal distance function. Experiment results on biological images show desirable performance and demonstrate the effectiveness of the proposed algorithm.     

Numerical solution of a Cauchy problem for Laplace equation in 3-dimensional domains by integral equations

A numerical method based on integral equations is proposed and investigated for the Cauchy problem for the Laplace equation in 3-dimensional smooth bounded doubly connected domains. To numerically reconstruct a harmonic function from knowledge of the function and its normal derivative on the outer of two closed boundary surfaces, the harmonic function is represented as a single-layer potential. Matching this representation against the given data, a system of boundary integral equations is obtained to be solved for two unknown densities. This system is rewritten over the unit sphere under the assumption that each of the two boundary surfaces can be mapped smoothly and one-to-one to the unit sphere. For the discretization of this system, Weinert’s method (PhD, Göttingen, 1990) is employed, which generates a Galerkin type procedure for the numerical solution, and the densities in the system of integral equations are expressed in terms of spherical harmonics. Tikhonov regularization is incorporated, and numerical results are included showing the efficiency of the proposed procedure.     

铜-A3钢爆炸焊接SE型专用炸药实验研究

炸药爆速不稳定和爆速过高是造成复合板结合质量差的主要原因.以2#岩石硝铵炸药为主体,通过加入一定比例的食盐、膨胀珍珠岩配制成了爆速可调的SE型爆炸焊接专用炸药,其加工方便,成本较低,最低爆速为2048m/s.铜-A3 钢爆炸焊接实验表明,该炸药具有爆速低、爆轰稳定、能量适中特点,较好地解决了猛炸药焊接时所出现的问题.研究和配置爆速更低、能够适应更多金属板材以及管状物体焊接的专用炸药是需要进一步研究的课题.     

Multifunctional modification of Fe3O4 nanoparticles for diagnosis and treatment of diseases: A review

With the rapid improvements in nanomaterials and imaging technology,great progresses have been made in diagnosis and treatment of diseases during the pastdecades.Fe₃O₄ magnetic nanoparticles(MNPs)with good biocompatibility and super-paramagnetic property are usually used as contrast agent for diagnosis of diseases inmagnetic resonance imaging(MRI).Currently,the combination of multiple imagingtechnologies has been considered as new tendency in diagnosis and treatment ofdiseases,which could enhance the accuracy and reliability of disease diagnosis andprovide new strategies for disease treatment.Therefore,novel contrast agents used formultifunctional imaging are urgently needed.Fe₃O₄ MNPs are believed to be a potentialcandidate for construction of multifunctional platform in diagnosis and treatment ofdiseases.In recent years,there are a plethora of studies concerning the construction ofmultifunctional platform presented based on Fe₃O₄ MNPs.In this review,we introducefabrication methods and modification strategies of Fe₃O₄ MNPs,expecting greatimprovements for diagnosis and treatment of diseases in the future.     

Effect of package light transmittance on the vitamin content of milk,part 3: Fortified UHT low‐fat milk

This work is the third and last part of a milk study evaluating the effect of package light transmittance on the vitamin content of milk, in this case on fortified UHT low‐fat milk. The milk was stored under light with an intensity of 700 lux in polyethylene terephthalate (PET) bottles with varying light transmittance to monitor the changes in the vitamin A, B₂ and D₃ contents over a storage period of 12 weeks at 23°C. Milk packed in pigmented PET bottles with the lowest light transmittance, which was stored in the dark under the same experimental conditions, served as the ‘control’ sample. In clear PET bottles, a reduction of 93% of the initial content was observed for vitamin A and 66% for vitamin D₃, while the vitamin B₂ content was completely degraded. In all pigmented PET bottles, the vitamin retention was only slightly higher; the losses ranged between 70 and 90% for vitamin A, between 63 and 95% for vitamin B₂, and between 35 and 65% for vitamin D₃ depending on the pigmentation level. In the dark‐stored ‘control’ sample, a 16% loss could be observed for vitamin A, while the level of vitamins B₂ and D₃ remained almost stable. Copyright © 2008 John Wiley & Sons, Ltd.     

Space‐Confined Growth of Individual Wide Bandgap Single Crystal CsPbCl3 Microplatelet for Near‐Ultraviolet Photodetection

Perovskite photodetectors (PDs) with tunable detection wavelength have attracted extensive attention due to the potential application in the field of imaging, machine vision, and artificial intelligence. Most of the perovskite PDs focus on I‐ or Br‐based materials due to their easy preparation techniques. However, their main photodetection capacity is situated in the visible region because of their narrower bandgap. Cl‐based wide bandgap perovskites, such as CsPbCl₃, are scarcely reported because of the bad film quality of the spin‐coated Cl‐based perovskite, due to the poor solubility of the precursor. Therefore, ultraviolet detection using high‐quality full inorganic perovskite films, especially with high thermal stability of materials and devices, is still a big challenge. In this work, high‐quality single crystal CsPbCl₃ microplatelets (MPs) synthesized by a simple space‐confined growth method at low temperature for near‐ultraviolet (NUV) PDs are reported. The single CsPbCl₃ MP PDs demonstrate a decent response to NUV light with a high on/off ratio of 5.6 × 10³ and a responsivity of 0.45 A W^?1 at 5 V. In addition, the dark current is as low as pA level, leading to detectivity up to 10¹¹ Jones. Moreover, PDs possess good stability and repeatability.     

Monotonic and low cycle fatigue behaviour of 2024‐T3 aluminium alloy between room temperature and 300 °C for designing VAWT components

In the present study, the results of the monotonic tension tests and low cycle fatigue tests performed on aluminium alloy EN AW‐2024‐T3 under various operating temperatures are presented in order to assess the fatigue behaviour of the aluminium alloy under evaluated temperatures. Monotonic tests were performed to determine the influence of temperature on mechanical properties of the material. The aim of cyclic tests was to acquire the parameters required for Manson–Coffin equation in order to plot strain–fatigue life curves. Moreover, stress–strain behaviour of the alloy and the cyclic hardening behaviour were evaluated using Ramberg–Osgood equation. Finally, P_SWT‐damage parameters for each temperature have been calculated for further investigation of the effects of the temperature on fatigue life using acquired data while taking the account of mean stress effect into calculations. Variations in the experimental data due to various test temperatures are presented for both monotonic and cyclic tests.