Numerical simulation of wave slamming on wedges and ship sections during water entry

Ma, Zhihua,Qian, Ling Techno-Press 2018 Ocean systems engineering Vol.8 No.2

The open source software OpenFOAM is utilised to simulate the water entry and hydrodynamic impact process of 2D wedges and ship hull sections. Incompressible multiphase flow solver interDyMFoam is employed to calculate the free fall of structure from air into water using dynamically deforming mesh technique. Both vertical and oblique entry of wedges of various dead-rise angles have been examined. A convergence study of dynamics as well as kinematics of the flow problem is carried out on successively refined meshes. Obtained results are presented and compared to the experimental measurements showing good agreement and reasonable mesh convergence of the solution.

Bayesian methods for dealing with missing data problems

Zhihua Ma,Guanghui Chen 한국통계학회 2018 Journal of the Korean Statistical Society Vol.47 No.3

Missing data, a common but challenging issue in most studies, may lead to biased and inefficient inferences if handled inappropriately. As a natural and powerful way for dealing with missing data, Bayesian approach has received much attention in the literature. This paper reviews the recent developments and applications of Bayesian methods for dealing with ignorable and non-ignorable missing data. We firstly introduce missing data mechanisms and Bayesian framework for dealing with missing data, and then introduce missing data models under ignorable and non-ignorable missing data circumstances based on the literature. After that, important issues of Bayesian inference, including prior construction, posterior computation, model comparison and sensitivity analysis, are discussed. Finally, several future issues that deserve further research are summarized and concluded.

Nonparametric analysis of income distributions among different regions based on energy distance with applications to China Health and Nutrition Survey data

Ma, Zhihua,Xue, Yishu,Hu, Guanyu The Korean Statistical Society 2019 Communications for statistical applications and me Vol.26 No.1

Income distribution is a major concern in economic theory. In regional economics, it is often of interest to compare income distributions in different regions. Traditional methods often compare the income inequality of different regions by assuming parametric forms of the income distributions, or using summary statistics like the Gini coefficient. In this paper, we propose a nonparametric procedure to test for heterogeneity in income distributions among different regions, and a K-means clustering procedure for clustering income distributions based on energy distance. In simulation studies, it is shown that the energy distance based method has competitive results with other common methods in hypothesis testing, and the energy distance based clustering method performs well in the clustering problem. The proposed approaches are applied in analyzing data from China Health and Nutrition Survey 2011. The results indicate that there are significant differences among income distributions of the 12 provinces in the dataset. After applying a 4-means clustering algorithm, we obtained the clustering results of the income distributions in the 12 provinces.

High expression of HOXC6 predicts a poor prognosis and induces proliferation and inflammation in multiple myeloma cells

Li Zhihua,Wang Yaru,Hou Xiaoxu,Guo Luyao,Li Yanling,Ma Yanping,Ma Yanping 한국유전학회 2023 Genes & Genomics Vol.45 No.7

Background Multiple myeloma (MM) is a common blood system malignance accompanied by monoclonal plasma cell hyperplasia. Homeobox C6 (HOXC6) acts as an oncogene in various cancers, but its function on MM is elusive. Objective The role of HOXC6 on MM development was clarified in this study. Methods HOXC6 expression and its clinical significance were determined in the peripheral blood samples collected from forty MM patients and thirty healthy adult volunteers. The overall survival was evaluated by Kaplan-Meier analysis with the log-rank test. Cell viability, proliferation and apoptosis were measured by CCK-8, EdU assay and Flow cytometry in U266 and MM.1R cells. Tumor growth was estimated by a xenograft assay. The apoptosis of tumor tissues was evaluated using TUNEL staining. The protein level in tissues was tested by immunohistochemistry. Results The HOXC6 expression was elevated in MM and high HOXC6 level was associated with the poor overall survival of MM. Besides, the HOXC6 expression was associated with hemoglobin level and ISS stage. Furthermore, silencing HOXC6 suppressed cell proliferation, induced cell apoptosis, and restrained the secretion of inflammatory factors (TNF-α, IL-6, and IL-8) in MM cells through inactivating the NF-κB pathway. Moreover, silencing HOXC6 suppressed the tumor growth of MM, the inflammatory factors levels, and the activation of NF-κB pathway but enhanced apoptosis in vivo. Conclusion HOXC6 was elevated in MM and associated with poor survival. Knockdown of HOXC6 suppressed proliferation, inflammation and tumorigenicity of MM cells via inactivating the NF-κB pathway. HOXC6 may be a meaningful target for MM therapy.

Effect of Ball Endc Cutterc Tilt Milling on Path Interval of Blade Surface

Jiaheng Ma,Fujian Ma,Ziguang Wang,Zhihua Sha,Shengfang Zhang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.10

Different milling posture of ball-end cutter will alter path interval and affect surface scallop-height, which was an important problem to be considered to enhance the quality and efficiency of blade surface. In view of ball end cutter tilt milling of blade surface, the relation equation between path interval and scallop-height was established by constant scallop-height method, based on the determination of collision boundary and milling sensitivity, the optimal tilt angles and path interval of blade surface milling were solved, moreover, by means of cutting simulation method, the differences between tilt milling and traditional non-tilt milling were compared and analyzed from the perspective of scallop height and processing time, and verified through comparative experiments. The results show that the optimal tilt angles of blade surface milling is 36.9°, when the path interval is fixed, the surface roughness of non-tilt milling and tilt milling are 0.719 µm and 0.561 µm respectively, the surface processing quality of tilt milling is 28.2% higher than that of non-tilt milling, when scallop-height is fixed, the total time of non-tilt milling and tilt milling are 31.21 min and 25.46 min respectively, the machining efficiency of tilt milling is 17.1% higher than that of non-tilt milling. The effectiveness of tilt milling method is verified, which can provide reference basis for high-quality and efficient machining of similar blade surfaces.

Experimental investigation and evaluation of the performance of air-source heat pumps for indoor thermal comfort control

Zhihua Wang,Fenghao Wang,Zhenjun Ma,Mengmeng Bai,Shuai Liu 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.3

Air-source heat pumps (ASHPs) have been widely used in domestic buildings. However, the regulation performance of ASHPs for indoor thermal comfort control is influenced by the factors such as cold draft and slow response to the variation in room temperature. In this paper, a range of experiments was carried out for 14 ASHPs in an indoor environmental chamber under both cooling and heating conditions. A multi-index comprehensive evaluation model including the questionnaire survey method, the weighted scoring method and the quartile algorithm method was then adopted to analyze the tested data in order to give some intuitive indices to evaluate the regulation performance of ASHPs for indoor thermal comfort control. The results showed that unsatisfied factor of the overall thermal comfort under the cooling conditions was reached to 71 %. Besides, the precision of the temperature control was poor in both cooling and heating conditions, which manifesting ASHPs need a novel matched adjust mode and more intelligent control system to meet thermal comfort requirement. This study provided a reference basis for evaluating ASHP’s regulation performance on indoor thermal comfort.

Flow separation control of two kinds of microvortex generators for a supersonic spinning projectile

Jie Ma,Zhen-gui Huang,Zhihua Chen,Da-wen Xue,Jun-li Han 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

Previous studies have shown that Microvortex generators (MVGs) can effectively control the flow separation of supersonic boundary layer. To improve the flight stability of a spinning projectile, two kinds of MVGs, micro ramps and vanes, are applied to control the flow separation of an original standard 155 mm projectile, respectively. Numerical simulations were performed with the use of Detached eddy simulation (DES) method, and the flow fields of the projectile with and without micro MVGs were simulated, the characteristics of the boundary layer and aerodynamic data of three cases were compared and discussed. The numerical results reveal that the effect of the MVGs control is obvious, but their mechanisms are different, and the vanes are more effective than the ramp in the boundary layer control. However, they can both improve the lift and pitching moment of the projectile, and eliminate their oscillations; as a result, its flight stability and firing dispersion can be enhanced. Our results can provide important guidance for improving the flight quality of supersonic projectiles.

Status of serum vitamin B₁₂ and folate in patients with inflammatory bowel disease in China

( Shaozhong Huang ),( Jiayi Ma ),( Mingming Zhu ),( Zhihua Ran ) 대한장연구학회 2017 Intestinal Research Vol.15 No.1

Background/Aims: Inflammatory bowel disease (IBD) primarily involves the intestinal tract and can affect vitamin absorption. This study was designed to assess the prevalence of vitamin B₁₂ and folate deficiencies in patients with IBD, and to identify the risk factors associated with abnormal serum vitamin B₁₂ and folate levels. Methods: We evaluated the medical records of 195 patients with Crohn`s disease (CD) and 62 patients with ulcerative colitis (UC), and selected 118 healthy subjects for the control group. Results: There were more CD patients with vitamin B₁₂ deficiency than UC patients (14.9% vs. 3.2%, P =0.014) and controls (14.9% vs. 4.2%, P =0.003). The prevalence of folate deficiency was higher in CD patients than in controls (13.3% vs. 3.4%, P =0.004). There were no significant differences in the serum vitamin B₁₂ and folate statuses of the UC and control groups. Patients with prior ileal or ileocolic resection showed a higher prevalence of abnormal vitamin B₁₂ levels than those without prior resection (n=6/16, n=23/179; P =0.018). A disease duration within 5 years was a risk factor of abnormal folate levels in CD patients. Conclusions: This study showed that vitamin B₁₂ and folate deficiencies were more common in patients with CD than in UC patients and controls. Prior ileal or ileocolonic resection was a risk factor of serum vitamin B₁₂ abnormalities, and a disease duration within 5 years was a risk factor of low serum folate levels in CD patients. (Intest Res 2017;15:103-108)

Diphenyl derivatives from coastal saline soil fungus Aspergillus iizukae

Desheng Liu,Ling Yan,Liying Ma,Yuling Huang,Xiaohong Pan,Weizhong Liu,Zhihua Lv 대한약학회 2015 Archives of Pharmacal Research Vol.38 No.6

Two new diphenyl derivatives, named iizukinesA (1) and B (2), along with nine known compounds wereisolated from coastal saline soil derived fungus Aspergillusiizukae. The structures were determined by extensivespectroscopic analysis. Their cytotoxicities were preliminarilyevaluated on HL-60, BEL-7402 and A-549 cell linesby the MTT assay.

Interactions between household air pollution and GWAS-identified lung cancer susceptibility markers in the Female Lung Cancer Consortium in Asia (FLCCA)

Hosgood III, H. Dean,Song, Minsun,Hsiung, Chao Agnes,Yin, Zhihua,Shu, Xiao-Ou,Wang, Zhaoming,Chatterjee, Nilanjan,Zheng, Wei,Caporaso, Neil,Burdette, Laurie,Yeager, Meredith,Berndt, Sonja I.,Landi, Ma Springer-Verlag 2015 HUMAN GENETICS Vol.134 No.3