A review on the coordinative structure of human walking and the application of principal component analysis

Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern of multi-segment movement and reveal the control mechanism. The degree of freedom and dimensional properties provide a view of the coordinative structure during walking, which has been extensively studied by using dimension reduction technique. In this paper, the studies related to the coordinative structure, dimensions detection and pattern reorganization during walking have been reviewed. Principal component analysis, as a popular technique, is widely used in the processing of human movement data. Both the principle and the outcomes of principal component analysis were introduced in this paper. This technique has been reported to successfully reduce the redundancy within the original data, identify the physical meaning represented by the extracted principal components and discriminate the different patterns. The coordinative structure during walking assessed by this technique could provide further information of the body control mechanism and correlate walking pattern with injury.

Evaluating journals' yearly impact with altmetric indicators

Purpose： Applying SSCI journals of library and information science （LIS） as the research sample, we explore the feasibility of measuring academic journals＇ yearly social impact by using altmetric indicators. Design/methodology/approach： Using a sample of 66 SSCI joumals in LIS published in 2013, statistics regarding journal mentions in social media and other online tools were retrieved from Altmetric.com and meanwhile citation data was also collected from JCR and Scopus. Based on the method of principal component analysis, data was analyzed for associations between the altmetric and traditional metrics to demonstrate the effect ofaltmetric indicators on measuring academic j oumals＇ yearly impact. Findings： The Spearman＇s rank correlation test results show that altmetric indicators and traditional citation counts were significantly correlated, indicating that altmetrics can be used to measure a journal＇s yearly social impact. Research limitations： The time frame of data collected from Altmetric.com may not be consistent with that of JCR and Scopus citation data. Practical implications： A new method is provided based on altmetrics for evaluating the social impact of academic journals, which can be applied to design new indicators of short-term journal impact. Originality value： In this paper, we have established a method for evaluating the social impact of academic journals based on altmetric indictors. Altmetrics can be complementary to traditional citation metrics in assessing a journal＇s impact within a year or even in a shorter period of time.

Relationship between Abnormal Characteristics of Sublingual Collateral and Portal Vein Hemodynamic Changes in Patients with Primary Hepatic Carcinoma

Objective： To investigate the relationship between the abnormal characteristics of sublingual collateral （SC） and portal vein hemodynamic changes in patients with primary hepatic carcinoma （PHC）. Methods： A total of 123 patients of PHC with abnormal SC were enrolled. The SC characteristics were classified and evaluated. The principal components （PC） of SC extracted from them by principal component analysis and the relationship between PC and the dynamic changes of portal vein flow were analyzed by correlation analysis. Results： Three groups of PC were extracted, namely PC-1 （length, width, presentation type of visualization）, PC-2 （circuitous, vesicular change）, and PC-3 （color, collateral hemostasis, petechiae, ecchymosis）. Their total accumulative contribution degree reached 56.803%. Correlation analysis shows that PC-1 was significantly positively correlated with the hemodynamic parameters of the portal vein （P〈0.01）, while PC-2 and PC-3 were not （P〉0.05）. Conclusion： Length, width and presentation type of SC could be used for predicting the changes of portal venous pressure in PHC patients.

Intelligent Multivariable Modeling of Blast Furnace Molten Iron Quality Based on Dynamic AGA-ANN and PCA

Blast furnace （BF） ironmaking process has complex and nonlinear dynamic characteristics. The molten iron temperature （MIT） as well as Si, P and S contents of molten iron is difficult to be directly measured online, and large-time delay exists in offline analysis through laboratory sampling. A nonlinear multivariate intelligent modeling method was proposed for molten iron quality （MIQ） based on principal component analysis （PCA） and dynamic ge- netic neural network. The modeling method used the practical data processed by PCA dimension reduction as inputs of the dynamic artificial neural network （ANN）. A dynamic feedback link was introduced to produce a dynamic neu- ral network on the basis of traditional back propagation ANN. The proposed model improved the dynamic adaptabili- ty of networks and solved the strong fluctuation and resistance problem in a nonlinear dynamic system. Moreover, a new hybrid training method was presented where adaptive genetic algorithms （AGA） and ANN were integrated, which could improve network convergence speed and avoid network into local minima. The proposed method made it easier for operators to understand the inside status of blast furnace and offered real-time and reliable feedback infor- mation for realizing close-loop control for MIQ. Industrial experiments were made through the proposed model based on data collected from a practical steel company. The accuracy could meet the requirements of actual operation.

Simultaneous optimization of multiple performance characteristics in WEDM for machining ZC63/SiC_p MMC

Abstract The compliance of an integrated approach, principal component analysis （PCA）, coupled with Tagu chi＇s robust theory for simultaneous optimization of cor related multiple responses of wire electrical discharge machining （WEDM） process for machining SiCp rein forced ZC63 metal matrix composites （MMCs） is investi gated in this work. The WEDM is proven better for its efficiency to machine MMCs among others, while the particulate size and volume percentage of SiCp with the composite are the utmost important factors. These improve the mechanical properties enormously, however reduce the machining performance. Hence the WEDM experiments are conducted by varying the particulate size, volume fraction, pulseon time, pulseoff time and wire tension. In the view of quality cut, the most important performance indicators of WEDM as surface roughness （Ra）, metal removal rate （MRR）, wire wear ratio （WWR）, kerf （Kw） and white layer thickness （WLT） are measured as respon ses. PCA is used as multiresponse optimization technique to derive the composite principal component （CPC） which acts as the overall quality index in the process. Consequently, Taguchi＇s S/N ratio analysis is applied to optimize the CPC. The derived optimal process responses are confirmed by the experimental validation tests results. The analysis of vari ance is conducted to find the effects of choosing process variables on the overall quality of the machined component.The practical possibility of the derived optimal process conditions is also presented using SEM.