学科服务 更多>>

关键词： Lateral passing distance   Dooring crash   Bicyclist   Motor vehicle   Comfort perception   Ambient traffic density  

摘要： This paper studies the relevant factors in mixed urban traffic that may impact the lateral spacing between bicycles and vehicles (passing distance, PD), and their resulting effect on a bicyclists' comfort based on a study of six sites in Ottawa, Canada. The observations are: [i] the average position of bicycles from the curb is 0.57 m, and lesser (Le. 0.35 m) in the presence of parking;[ii] 90% of passes exceed 1.23 m;[iii] PD is positively correlated with motor vehicle speed, lane width, and bicycle position from adjacent curb edge line, whiles inversely correlated to ambient traffic density and bicycle speed;[iv] motor vehicle speed has the highest prediction of PD variability;[v] PD and ambient traffic density (ATD) are found to be the most important factors to a bicyclists' comfort perception (BCP). Two linear regression models for PD and BCP were developed and significant variables are identified as: motor vehicle speed, bicycle speed, ATD, number of lanes, and lane width. The presence or absence of a grade slope is found to be significant to the PD model and not to BCP. The models both exhibit limited predictive ability, however residual plots and significance of included variables are indicative of correct assumptions for the models. It is recommended that speed calming, sharrows, road signs instructing road sharing, and educating road users against "dooring" crashes be considered in improving road sharing, especially for narrow lanes (i.e. less than 3.6 m) and lanes wider than 4.5 m. It is also prudent for designers to avoid installing parking zones on narrow shared roads.

关键词： Biosignal   decision tree   delay embedding (DE)   low-voltage alternating current electrokinetics (ACEK)   persistent homology   topology   witness complex.  

摘要： Goal: Bucking the trend of big data, in microdevice engineering, small sample size is common, especially when the device is still at the proof-of-concept stage. The small sample size, small interclass variation, and large intraclass variation, have brought biosignal analysis new challenges. Novel representation and classification approaches need to be developed to effectively recognize targets of interests with the absence of a large training set. Methods: Moving away from the traditional signal analysis in the spatiotemporal domain, we exploit the biosignal representation in the topological domain that would reveal the intrinsic structure of point clouds generated from the biosignal. Additionally, we propose a Gaussian-based decision tree (GDT), which can efficiently classify the biosignals even when the sample size is extremely small. Results: This study is motivated by the application of mastitis detection using low-voltage alternating current electrokinetics (ACEK) where five categories of bisignals need to be recognized with only two samples in each class. Experimental results demonstrate the robustness of the topological features as well as the advantage of GDT over some conventional classifiers in handling small dataset. Conclusion: Our method reduces the voltage of ACEK to a safe level and still yields high-fidelity results with a short assay time. Significance: This paper makes two distinctive contributions to the field of biosignal analysis, including performing signal processing in the topological domain and handling extremely small dataset. Currently, there have been no related works that can efficiently tackle the dilemma between avoiding electrochemical reaction and accelerating assay process using ACEK.

关键词： feature selection   generalized partial least squares regression   small samples   land cover   OBIA  

摘要： Land cover information extraction through object-based image analysis (OBIA) has become an important trend in remote sensing, thanks to the increasing availability of high-resolution imagery. Segmented objects have a large number of features that cause high-dimension and low-sample size problems in the classification process. In this study, on the basis of a partial least squares generalized linear regression (PLSGLR), we propose a group corrected PLSGLR, known as G-PLSGLR, that aims to reduce the redundancy of object features for land cover identifications. Using Gaofen-2 images, the area of interest was segmented and sampled to generate small sample-size training datasets with 51 object features. The features selected by G-PLSGLR were compared against a guided regularized random forest (GRRF) in metrics of reduction rate, feature redundancy, and accuracy assessment of classification. Three indicators of overall accuracy (OA), user's accuracy (UA), and producer's accuracy (PA) were applied for accuracy assessment in this paper. The result shows that the G-PLSGLR achieved a reduction rate of 9.27 with a feature redundancy of 0.29, and a value of OA 90.63%. The GRRF achieved a reduction rate of 1.61 with a feature redundancy of 0.42, and a value of OA 85.56%. The PA of each land cover category was more than 95% using features selected by G-PLSGLR, while the PA ranged from 77 to 96% using features selected by GRRF. The UA of G-PLSGLR-selected features ranged from 70 to 80% except for grass land and bare land, which achieved 10% higher UA than GRRF-selected features. The G-PLSGLR method we proposed has the advantages of a large reduction rate, low feature redundancy, and high classification performance, which can be applied in OBIA-based land cover classification.

关键词： physiologically based pharmacokinetic modeling   drug interactions   Monte Carlo   in vitro-in vivo correlations (IVIVC)   nonlinear regression   biliary excretion   biliary recycling   hepatic metabolism   hepatic transport  

摘要： Hypothetical substrates undergoing transporter-mediated hepatic uptake, metabolism, and enterohepatic circulation with different rate-determining processes with a combination of inhibition constants (K-i) for hepatic uptake, metabolism, and biliary excretion processes were generated with a constant K-i for uptake and incorporated into a physiologically based pharmacokinetic model. Analyses of the kinetic model suggested that the fraction of substrates excreted in the bile to the total elimination by the liver (f(bile)) can be estimated under certain conditions from kinetic analyses of their blood concentration-time profiles. Using the generated time profiles of substrates with and without coadministration of inhibitors, various pharmacokinetic parameters involving f(bile) and K-i for the hepatic uptake, metabolism, and biliary excretion of drugs were back-calculated by fitting. Comparing parameters obtained with the original parameter sets by fitting, the K-i were found to be well estimated under the following conditions: the initial estimates for inhibition constants were relatively good, which corresponds to the case for obtaining reliable in vitro inhibition constants. In conclusion, the integration of top-down analyses with bottom-up estimates (experimental determination) of inhibition constants can be used to estimate in vivo inhibition constants and f(bile) reliably. (C) 2017 American Pharmacists Association (R). Published by Elsevier Inc. All rights reserved.

关键词： Problem posing   Problem solving   Interaction   Mathematics conceptual understanding   Prospective primary teachers  

摘要： Existing studies have quantitatively evidenced the relatedness between problem posing and problem solving, as well as the magnitude of this relationship. However, the nature and features of this relationship need further qualitative exploration. This paper focuses on exploring the interactions, i.e., mutual effects and supports, between problem posing and problem solving. More specifically, this paper analyzes the forms of interactions that happened between these two activities, the ways that those interactions supported prospective primary teachers' conceptual understanding, and the difficulties that prospective teachers encountered while engaged in alternating problem-posing and problem-solving activities. The results indicate that problem posing contributes to problem-solving effectiveness while problem solving supports participants in posing more reasonable problems. Finally, multiple difficulties that demonstrate prospective primary teachers' misunderstanding with fractions and their operations provide insight for teacher educators to design problem-posing tasks involving fractions.

关键词： 食品检验   实验室管理   质量体系  

摘要： 近些年来,我国格外重视食品的安全检验工作,这是因为食品关乎着人们的日常生活与生命健康,所以食品产业实现管理运营的规范化、集约化发展,是一种必然趋势.将质量体系应用在食品检验以及实验管理过程当中,可以有效对食品检验工作进行必要的质量管理,同时可以切实提高食品管理水平。本文以实验室管理的实践经验和体会为例,阐述了在食品实验室管理中如何更好地发挥质量管理体系的作用。

关键词： 贫血鉴别诊断   血液检验   临床应用  

摘要： 据世界卫生组织研究报告表明,人群中大概有20%的人患有贫血。贫血虽然不作为一种具体的疾病,但是其可以引发多种系统疾病的产生。贫血的类型繁多,在治疗前必须进行贫血鉴别诊断才能够明确具体的治疗方法。血液检验是鉴别贫血类型的主要手段,在临床方面应用广泛。

关键词： Spectroscopy   Fuel classification   Wavenumber selection   Diesel/biodiesel  

摘要： In recent years, spectroscopy techniques such as Near infrared (NIR) and Fourier Transform Infrared (Frill) have been widely adopted as analytical tools in different fields and with several purposes. NIR and MR data are typically comprised of hundreds or even thousands of highly correlated wavenumbers, fact that can jeopardize the accuracy of several statistical techniques. In light of that, wavenumber selection emerges as an important step in prediction and classification tasks based on spectroscopy data. This paper proposes a novel framework for wavenumber selection aimed at classifying samples into proper categories, which is applied to two data sets from the petroleum sector. The method relies on two main stages: determination of intervals based on the distance between the average spectra of the classes and selection of the most suitable intervals through cross-validation. An improvement in the misclassification rate was achieved for a NIR spectra data set of diesel, decreasing that metric from 13.90% to 11.63% after the application of the proposed method while retaining 23.19% of the original wavenumbers. As for the biodiesel STIR data set, the method yielded a misclassification rate of 1.21% while retaining 4.95% of the original variables;misclassification rate was 4.71% when all wavenumbers were used. The proposed method also outperformed traditional approaches for wavenumber selection.

关键词： feature extraction   switchgear   entropy   fault diagnosis   power engineering computing   data mining   time series   fuzzy set theory   support vector machines   signal classification   feature extraction   fault feature classification method   switchgear faults   sample entropy   fault diagnosis method   multivariate multiscale sample entropy   MMSE   data mining   composite delay vectors   multivariate multiscale cloud sample entropy   MMCSE features   switchgear monitoring data   fuzzy support vector machine   FSVM   dropping seminormal membership cloud model   uncertainty quantification   smart breaker   sensors   three-phase voltage   multivariate monitoring process   multivariate time series   tolerance criterion  

摘要： This study proposes a fault diagnosis method for extracting and classifying the fault features of switchgears in accordance with the monitoring data of three-phase voltage and current, temperature, humidity, and flashing from the smart breaker and sensors. The fault features are calculated using multivariate multiscale sample entropy (MMSE) for the data mining of multivariate monitoring process. The similarity measure of the composite delay vectors of multivariate time series in MMSE is improved by introducing a cloud model to soften the similar tolerance criterion. The modified MMSE is defined as multivariate multiscale cloud sample entropy (MMCSE). The MMCSE features of switchgear monitoring data can be achieved in different time scales in describing various switchgear faults. Subsequently, a classification method based on fuzzy support vector machine (FSVM) is further adopted to identify different types of switchgear faults using the MMCSE features. In addition, a dropping semi-normal membership cloud model is applied to modify the uncertainty quantification of the relationship among fault samples in FSVM. The effectiveness of the proposed method is validated with the monitoring data in a 10kV switchboard.

关键词： 食用农产品   食品   加工   定量包装   企业的性质   分类   质量控制标准   农业活动  

摘要： 食品与食用农产品区分的核心在于产品的性质以及生产时的质量控制标准,而非生产企业的性质。食用农产品作为在农业活动中直接获得的可供食用的植物、动物、微生物及其产品,与食品的区别在于其未经过任何加工和处理,或虽经过简单加工,但并未改变其基本自然性状和化学性质。