Robust variable selection for the varying index coefficient models

Zou Hang,Jiang Yunlu 한국통계학회 2023 Journal of the Korean Statistical Society Vol.52 No.4

Recently, the statistical inference of the varying index coefficient model has been widely concerned. However, to the best of our knowledge, there has no existing robust variable selection method for the varying index coefficient model in the presence of outliers in the response and covariates. To overcome this difficulty, we develop a robust variable selection method for the varying index coefficient model via the exponential squared loss (ESL) function in this article. We first approximate nonparametric functions by B-spline basis functions and then apply the minorization-maximization (MM) algorithm and the Fisher scoring algorithm to calculate the proposed estimators. Under some mild conditions, the theoretical properties of the proposed estimators are established. Furthermore, we propose a data-driven procedure to select the tuning parameters. Some numerical simulations are conducted to illustrate the finite sample performance of the proposed method. Finally, the analysis of New Zealand workforce data reveals the merit of the proposed method.

A method to analyze the difference of 3-D CAD model files based on feature extraction

Zou Linghao,Guo Dongming,Gao Hang 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.4

To quickly find the changes in two 3-D CAD model files and enhance the efficiency and security of transmission in the CAD collaborative design system, a method to compare and analyze the differences of 3-D CAD model files is proposed. First, the feather information of CAD files was extracted using APIs of CAD software and stored in the neutral feature file. Then, analyzing and comparing the feature file, the information about adding, updating and deleting was obtained by the given algorithm. Finally, the information was rendered and showed to users in a readable method. The application in Catia validated that the proposed method is feasible and valuable in engineering.

Proteomic Mapping of the Human Mitochondrial Intermembrane Space in Live Cells via Ratiometric APEX Tagging

Hung, V.,Zou, P.,Rhee, H.W.,Udeshi, Namrata D.,Cracan, V.,Svinkina, T.,Carr, Steven A.,Mootha, Vamsi K.,Ting, Alice Y. Cell Press 2014 Molecular cell Vol.55 No.2

Obtaining complete protein inventories for subcellular regions is a challenge that often limits our understanding of cellular function, especially for regions that are impossible to purify and are therefore inaccessible to traditional proteomic analysis. We recently developed a method to map proteomes in living cells with an engineered peroxidase (APEX) that bypasses the need for organellar purification when applied to membrane-bound compartments; however, it was insufficiently specific when applied to unbounded regions that allow APEX-generated radicals to escape. Here, we combine APEX technology with a SILAC-based ratiometric tagging strategy to substantially reduce unwanted background and achieve nanometer spatial resolution. This is applied to map the proteome of the mitochondrial intermembrane space (IMS), which can freely exchange small molecules with the cytosol. Our IMS proteome of 127 proteins has >94% specificity and includes nine newly discovered mitochondrial proteins. This approach will enable scientists to map proteomes of cellular regions that were previously inaccessible.

Hot Deformation Behaviors of Ti-22Al-26Nb-2Ta Alloy Based on GA-LSSVM and 3D Processing Map

Peng Wan,Hang Zou,Kelu Wang,Zhengzhi Zhao 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

The thermal compression tests of Ti-22Al-26Nb-2Ta alloy under T = 1173 ~ 1423 K and ̇ = 0.001 ~ 10 s−1 were carried out onthe Gleeble-3500 thermo-mechanical simulator. The flow stress curves were obtained, and the high-temperature rheologicalproperties of the alloy were analyzed. The 3D activation energy maps were calculated and constructed. The least squaressupport vector machine (LSSVM) model of constitutive relation was established, and the penalty coefficient and kernelparameter of the LSSVM model were optimized by genetic algorithm (GA). The constitutive model of the alloy based on theGA-LSSVM algorithm was constructed. The predicted value of the model was also compared with the experimental data. The dynamic material model (DMM) and polar reciprocity model (PRM) were used to establish the 3D processing map ofthe alloy and appropriate thermal processing parameters. Our researches indicated that deformation temperature and strainrate have a great influence on the flow stress of Ti-22Al-26Nb-2Ta alloy. Ti-22Al-26Nb-2Ta alloy is a negative temperaturesensitiveand a positive strain rate-sensitive material. The correlation coefficient of GA-LSSVM algorithm constitutive modelis 0.9922, and the relative error of most samples is within 10%, accounting for 93.18%. The model has high prediction accuracyand strong generalization ability. The DMM processing map based on the Prasad instability criterion is more accurate inoptimizing the processing parameters of the alloy than that of the PRM processing map through analyzing the 3D processingmap and observing the microstructure. The instability modes in the instability region of the alloy mainly include adiabaticshear, crack, and local flow. The 1173 ~ 1273 K/0.001 ~ 0.003 s−1 are the best parameters during the processing of the alloy.

SIMULATION AND MODELING OF DYNAMIC FRICTION COEFFICIENT OF WET CLUTCH DURING ENGAGEMENT

Zhigang Zhang,Ling Zou,Hang Liu,Yonglong Chen,Benzhu Zhang 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.1

A dynamic friction coefficient model in engagement was established based on the friction transmission mechanism of a wet clutch. The effects of parameters, such as the material permeability, surface roughness, Young’s modulus, ATF viscosity, applied pressure, initial relative angular velocity, and pressure delay time, on the friction coefficient during engagement were investigated. The results indicated that material permeability has a greater influence on the time when the dynamic friction coefficient tends to be stable, choosing an appropriate permeability of friction material can effectively prevent excessive the level of jerk during the engagement and excessive engagement time. Surface roughness and applied pressure mainly affect the magnitude of the initial and midpoint friction coefficients. Appropriately increasing the surface roughness and applied pressure can increase the smoothness of the engagement of wet clutch. The ATF viscosity and initial relative angular velocity have a significant effect on the magnitude of the initial friction coefficients. Appropriately increasing the ATF viscosity and initial relative angular velocity will reduce the level of jerk at the end of the wet clutch engagement. Young’s modulus and the pressure delay time have a smaller effect on the dynamic friction coefficient than that of other parameters.

Combining Non-Contrast CT Signs With Onset-to-Imaging Time to Predict the Evolution of Intracerebral Hemorrhage

Song Lei,Qiu Xiaoming,Zhang Cun,Zhou Hang,Guo Wenmin,Ye Yu,Wang Rujia,Xiong Hui,Zhang Ji,Tang Dongfang,Zou Liwei,Wang Longsheng,Yu Yongqiang,Guo Tingting 대한영상의학회 2024 Korean Journal of Radiology Vol.25 No.2

Objective: This study aimed to determine the predictive performance of non-contrast CT (NCCT) signs for hemorrhagic growth after intracerebral hemorrhage (ICH) when stratified by onset-to-imaging time (OIT). Materials and Methods: 1488 supratentorial ICH within 6 h of onset were consecutively recruited from six centers between January 2018 and August 2022. NCCT signs were classified according to density (hypodensities, swirl sign, black hole sign, blend sign, fluid level, and heterogeneous density) and shape (island sign, satellite sign, and irregular shape) features. Multivariable logistic regression was used to evaluate the association between NCCT signs and three types of hemorrhagic growth: hematoma expansion (HE), intraventricular hemorrhage growth (IVHG), and revised HE (RHE). The performance of the NCCT signs was evaluated using the positive predictive value (PPV) stratified by OIT. Results: Multivariable analysis showed that hypodensities were an independent predictor of HE (adjusted odds ratio [95% confidence interval] of 7.99 [4.87–13.40]), IVHG (3.64 [2.15–6.24]), and RHE (7.90 [4.93–12.90]). Similarly, OIT (for a 1-h increase) was an independent inverse predictor of HE (0.59 [0.52–0.66]), IVHG (0.72 [0.64–0.81]), and RHE (0.61 [0.54– 0.67]). Blend and island signs were independently associated with HE and RHE (10.60 [7.36–15.30] and 10.10 [7.10–14.60], respectively, for the blend sign and 2.75 [1.64–4.67] and 2.62 [1.60–4.30], respectively, for the island sign). Hypodensities demonstrated low PPVs of 0.41 (110/269) or lower for IVHG when stratified by OIT. When OIT was ≤ 2 h, the PPVs of hypodensities, blend sign, and island sign for RHE were 0.80 (215/269), 0.90 (142/157), and 0.83 (103/124), respectively. Conclusion: Hypodensities, blend sign, and island sign were the best NCCT predictors of RHE when OIT was ≤ 2 h. NCCT signs may assist in earlier recognition of the risk of hemorrhagic growth and guide early intervention to prevent neurological deterioration resulting from hemorrhagic growth.

Facile synthesis and characterization of GO/ZnS nanocomposite with highly efficient photocatalytic activity

Lingwei Li,Shaolin Xue,Pei Xie,Hange Feng,Xin Hou,Zhiyuan Liu,Zhuoting Xu,Rujia Zou 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.6

ZnS nanowalls, microspheres and rice-shaped nanoparticles have been successfully grown on graphene oxide (GO) sheets bythe hydrothermal method. The morphologies, structures, chemical compositions and optical properties of the as-synthesizedGO/ZnS have been characterized by X-ray power diff raction, energy dispersive spectrometer, scanning electron microscope,Raman spectra, photoluminescence spectroscopy and ultraviolet–visible absorption spectroscopy. It was found that theconcentration of CTAB and the reaction temperature were important in the formation of GO/ZnS microstructures. The photocatalyticactivity of the as-synthesized GO/ZnS was investigated through the photocatalytic degradation of textile dyeingwaste. Results showed that the catalytic activity of the GO/ZnS porous spheres to methyl orange and methylene blue is higherthan those of other samples. The degradation rates of methyl orange and methylene blue by porous spheres in 50 min were97.6 and 97.1%, respectively. This is mainly attributed to the large specifi c surface area of GO/ZnS porous spheres and highseparation effi ciency between photogenerated electron and hole pairs.