Some Properties of the Closure Operator of a Pi-space

Mao, Hua,Liu, Sanyang Department of Mathematics 2011 Kyungpook mathematical journal Vol.51 No.3

In this paper, we generalize the definition of a closure operator for a finite matroid to a pi-space and obtain the corresponding closure axioms. Then we discuss some properties of pi-spaces using the closure axioms and prove the non-existence for the dual of a pi-space. We also present some results on the automorphism group of a pi-space.

Sports Video Structure Analysis and Feature Extraction in Long Jump Video

Maohua Zhuang 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.9

How to help people to find their favorite sports in the massive video, in order to achieve this goal in the finite state machine (FSM) theory based on in-depth research. Combined with the actual situation of this paper, first, we determined the reasonable FSM model. Then, a fast robust global motion estimation algorithm is used to estimate the global motion of the video sequences, and the foreground is separated from the background by motion compensation. After the foreground of the video, a series of image feature extraction algorithm, which is based on the main color histogram and histogram, is used to extract the low level feature extraction. Finally, the results of the experimental operation, the performance of the algorithm, and the results of the system are presented.

Improvement of Pyruvate Production Based on Regulation of Intracellular Redox State in Engineered Escherichia coli

Maohua Yang,Jianmin Xing 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.4

The commercial demand for pyruvate has been expanding. However, some challenges need to be overcome in the microbial production of pyruvate, such as low glucose consumption caused by excessive accumulation of NADH. In this study, weakening or block of the TCA cycle, overexpression of foreign NADH oxidase, and carbon sources with different oxidation state was attempted to decrease NADH accumulation in engineered strain YP211. Results showed that blocking or weakening TCA cycle could not lower the intracellular redox state in strain YP211.Overexpressing NADH oxidase from Lactococcus lactis significantly decreased the intracellular NADH content and increased the consumption rate of glucose. However, the yield of pyruvate did not increase significantly. Compared with glucose as carbon source, sodium gluconate with a higher oxidation state resulted in a significant decrease of NADH/NAD+, and the concentration and yield of pyruvate increased by 62 and 6%, respectively. In the fed-batch fermentation, the yield of pyruvate increased to 0.78 g/g gluconate, and the concentration of pyruvate reached 78.8 g/L. It was suggested that sodium gluconate was a more ideal carbon source for strain YP211, which could effectively decrease NADH content and improve the pyruvate production.

The Control and Data Processing of the Multi-mode Microwave Remote Sensor

Maohua, Sun,Xiaohui, Zhang,Wei, Guo 대한원격탐사학회 2001 International Symposium on Remote Sensing Vol.17 No.1

The multi-mode microwave remote sensor consists of altimeter(ALT), scatterometer(SCAT) and radiometer(RAD), it is designed for space platform The data manage and control unit is the center of the instrument. Main function of the unit is producing the scheduling, controlling every mode to finish it's working, collecting data, receiving and executing the commands from space platform or ground, transmitting parameters and science data to the earth. Because the system will be applied on space platform, in order to make it safer, some designs in software and hardware were added in the data manage and control unit.

Dynamic Parameters Updating of Earth-rock Dams Based on Modal Parameter Identification

Maohua Wang,Shichun Chi,Zhenping Liu 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.10

The reasonable selection of dynamic parameters of earth-rock dams is very important for the seismic safety assessment of dams. Because of the size effects, the parameters acquired from the indoor test may additionally no longer exactly reflect the real dynamic characteristics of the dam. Therefore, it is essential to correct and update the dynamic parameters in accordance to the actual seismic dynamic characteristics of the dam. In this paper, by combining the Covariance-driven stochastic subspace identification (SSI-COV) method and the multiple population genetic algorithm (MPGA), an optimization and updating method for the dynamic parameters of earth-rock dams based on modal parameter identification is presented. The collected weak earthquake records of the dam allowed the modal parameters (the natural frequencies and mode shapes) identification based on SSI-COV method. The optimization updated is performed using the MPGA, which can obtain the optimal values of dynamic parameters of the dam and has good robustness within the optimization range of the numerical model. A typical numerical example is given to exhibit the feasibility and effectiveness of the presented method. Then the dynamic parameters of Liyutan Dam are updated by the proposed method according to the weak earthquake records, and the accuracy and applicability of the updated parameters were further verified by the strong earthquake records. The results show that the method proposed in this paper can provide a good idea for the calibration of dynamic parameters of earth-rock dams and has well practical engineering value.

Biomechanical Study of Cervical Endplate Removal on Subsidence and Migration in Multilevel Anterior Cervical Discectomy and Fusion

Lin Maohua,Paul Rudy,Shapiro Stephen Z.,Doulgeris James,O’Connor Timothy E.,Tsai Chi-Tay,Vrionis Frank D. 대한척추외과학회 2022 Asian Spine Journal Vol.16 No.5

Study Design: This study compares four cervical endplate removal procedures, validated by finite element models.Purpose: To characterize the effect of biomechanical strength and increased contact area on the maximum von Mises stress, migration, and subsidence between the cancellous bone, endplate, and implanted cage.Overview of Literature: Anterior cervical discectomy and fusion (ACDF) has been widely used for treating patients with degenerative spondylosis. However, no direct correlations have been drawn that incorporate the impact of the contact area between the cage and the vertebra/endplate.Methods: Model 1 (M1) was an intact C2C6 model with a 0.5 mm endplate. In model 2 (M2), a cage was implanted after removal of the C4–C5 and C5–C6 discs with preservation of the osseous endplate. In model 3 (M3), 1 mm of the osseous endplate was removed at the upper endplate. Model 4 (M4) resembles M3, except that 3 mm of the osseous endplate was removed.Results: The range of motion (ROM) at C2C6 in the M2–M4 models was reduced by at least 9º compared to the M1 model. The von Mises stress results in the C2C3 and C3C4 interbody discs were significantly smaller in the M1 model and slightly increased in the M2–M3 and M3–M4 models. Migration and subsidence decreased from the M2–M3 model, whereas further endplate removal increased the migration and subsidence as shown in the transition from M3 to M4.Conclusions: The M3 model had the least subsidence and migration. The ROM was higher in the M3 model than the M2 and M4 models. Endplate preparation created small stress differences in the healthy intervertebral discs above the ACDF site. A 1 mm embedding depth created the best balance of mechanical strength and contact area, resulting in the most favorable stability of the construct.

A Review of Finite Element Modeling for Anterior Cervical Discectomy and Fusion

Lin Maohua,Paul Rudy,Dhar Utpal Kanti,Doulgeris James,O’Connor Timothy E.,Tsai Chi-Tay,Vrionis Frank D. 대한척추외과학회 2023 Asian Spine Journal Vol.17 No.5

The cervical spine poses many complex challenges that require complex solutions. Anterior cervical discectomy and fusion (ACDF) has been one such technique often employed to address such issues. In order to address the problems with ACDF and assess the modifications that have been made to the technique over time, finite element analyses (FEA) have proven to be an effective tool. The variations of cervical spine FEA models that have been produced over the past couple of decades, particularly more recent representations of more complex geometries, have not yet been identified and characterized in any literature. Our objective was to present material property models and cervical spine models for various simulation purposes. The outlining and refinement of the FEA process will yield more reliable outcomes and provide a stable basis for the modeling protocols of the cervical spine.

Enhanced Sulfate Reduction by Citrobacter sp. Coated with Fe3O4/SiO2 Magnetic Nanoparticles

Wei Zhou,Maohua Yang,Ziyu Song,Jianmin Xing 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.1

A sulfate-reducing Citrobacter strain was isolatedand coated with Fe3O4/SiO2 magnetic nanoparticles(MNPs) to enhance sulfate reduction. Biolog analysisshowed that it utilizes a broad range of electron donors. The findings also showed that this bacteria strain is afacultative anaerobe and can completely reduce 12 mM ofsulfate to sulfide in 7 days under anaerobic conditions. Moreover, sulfate reduction was enhanced by 79% underoptimized conditions. Different SiO2 wrap-ratios of theMNPs attached to the cell surface were studied to optimizethe sulfate reduction: the surface of cells coated with 300%silica wrap-ratio MNPs showed the highest stability andincreased desulfurization batch time, with a 450% increasein sulfate reduction in comparison with uncoated cellscultivated in anaerobic conditions.

Study of Spaceborne W-band Millimeter Wave Radiometer

Jing, Li,Shengwei, Zhang,Maohua, Sun,Decai, Kong,Heguang, Liu,Jingshan, Jiang 대한원격탐사학회 2001 International Symposium on Remote Sensing Vol.17 No.1

The W-band millimeter wave radiometer has been studied under the support of Chinese Academy of Science (CAS) and it is successfully studied for the first time in China. Its technical index is suitable for the use in space. The main characteristics of the W-band millimeter wave radiometer are introduced in this paper.

Development of a Quantitative Assay Method for a Lytic Polysaccharide Monooxygenase

Mi-Ji Yu,Young-Jong Kim,Maohua Qu,Young-Wan Kim 한국당과학회 2016 한국당과학회 학술대회 Vol.2016 No.01

Lytic polysaccharide monooxygenases (LPMOs) are copper ion containing enzymes to cleave crystalline cellulose or chitin through an oxidative mechanism. Despite the importance of LPMOs for biomass decomposition, basic biochemical methods for characterizing LPMOs, such as activity assays are not well developed. Generally, LPMO activity has been determined by HPLC analysis of the product by simultaneous action of a LPMO and one of a cellulase and a chitinase depending on LPMO’s substrate specificity. Recently a spectrophotometric method has been developed using the side reaction of LPMOs to produce H2O2 in the absence of polysaccharide substrates. However, both assay methods do not give the information about polysaccharide lysis by only LPMOs. In this study, we developed an assay method for LPMOs based on the consumption of ascorbic acid that was used as an external electron donor for LPMOs. The assay method allowed determining the concentration-dependent activity of a chitin active LPMO from Bacillus atrophaeus 1942. This assay method would be a useful tool for detail characterization of LPMOs.