Modularizing Legacy System through an Improved Bunch Clustering Method in Cloud Migration

Junfeng Zhao,Jiantao Zhou,Hongji Yang 보안공학연구지원센터 2015 International Journal of Grid and Distributed Comp Vol.8 No.4

As a new service mode in cloud computing, SaaS (software as a service) brings many attractive advantages. Legacy systems can be revived through being reengineered to SaaS. In order to achieve reengineering, the analysis and understanding to legacy systems are essential. For this goal, an improved Bunch clustering system is proposed to implement automatic modularization to object-oriented software systems so as to help engineer understand legacy system, including introduction of modular dependency graph with relationship type information, adaptation to initial partition and adjustment to modularization quality. The experiment results show that the improvement of Bunch clustering system is effective. The improved Bunch clustering system can make the clustering results more stable and consistent to the benchmarks.

Sodium nitrate modified SBA-15 and fumed silica for efficient production of acrylic acid and 2,3-pentanedione from lactic acid

Junfeng Zhang,Weijie Ji,Chak-Tong Au,Xinzhen Feng,Yuling Zhao 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

The catalytic conversion of lactic acid to acrylic acid and 2,3-pentanedione over sodium nitrate-supported mesoporous SBA-15 and fumed silica was studied. The yields of acrylic acid, 2,3-pentanedione, and acetaldehyde are 44.8%, 25.1%, and 13.3%, respectively, over the 23%NaNO3/SBA-15 catalyst. The performance of the catalysts is strongly affected by NaNO3 loading, catalyst texture and porosity, and product diffusion efficiency. A proper control of NaNO3 loading can result in modification catalyst structure for improvement of 2,3-pentanedione selectivity. Under certain reaction conditions, the surface NaNO3 species can readily transform to sodium lactate that functions as active component to catalyze the target reactions.

Effect of storage time and the level of formic acid on fermentation characteristics, epiphytic microflora, carbohydrate components and in vitro digestibility of rice straw silage

Zhao Jie,Wang Siran,Dong Zhihao,Li Junfeng,Jia Yushan,Shao Tao 아세아·태평양축산학회 2021 Animal Bioscience Vol.34 No.6

Objective: The study aimed to evaluate the effect of storage time and formic acid (FA) on fermentation characteristics, epiphytic microflora, carbohydrate components and in vitro digestibility of rice straw silage. Methods: Fresh rice straw was ensiled with four levels of FA (0%, 0.2%, 0.4%, and 0.6% of fresh weight) for 3, 6, 9, 15, 30, and 60 d. At each time point, the silos were opened and sampled for chemical and microbial analyses. Meanwhile, the fresh and 60-d ensiled rice straw were further subjected to in vitro analyses. Results: The results showed that 0.2% and 0.6% FA both produced well-preserved silages with low pH value and undetected butyric acid, whereas it was converse for 0.4% FA. The populations of enterobacteria, yeasts, moulds and aerobic bacteria were suppressed by 0.2% and 0.6% FA, resulting in lower dry matter loss, ammonia nitrogen and ethanol content (p<0.05). The increase of FA linearly (p<0.001) decreased neutral detergent fibre and hemicellulose, linearly (p<0.001) increased residual water soluble carbohydrate, glucose, fructose and xylose. The in vitro gas production of rice straw was decreased by ensilage but the initial gas production rate was increased, and further improved by FA application (p<0.05). No obvious difference of FA application on in vitro digestibility of dry matter, neutral detergent fibre, and acid detergent fibre was observed (p>0.05). Conclusion: The 0.2% FA application level promoted lactic acid fermentation while 0.6% FA restricted all microbial fermentation of rice straw silages. Rice straw ensiled with 0.2% FA or 0.6% FA improved its nutrient preservation without affecting digestion, with the 0.6% FA level best. Objective: The study aimed to evaluate the effect of storage time and formic acid (FA) on fermentation characteristics, epiphytic microflora, carbohydrate components and <i>in vitro</i> digestibility of rice straw silage.Methods: Fresh rice straw was ensiled with four levels of FA (0%, 0.2%, 0.4%, and 0.6% of fresh weight) for 3, 6, 9, 15, 30, and 60 d. At each time point, the silos were opened and sampled for chemical and microbial analyses. Meanwhile, the fresh and 60-d ensiled rice straw were further subjected to <i>in vitro</i> analyses.Results: The results showed that 0.2% and 0.6% FA both produced well-preserved silages with low pH value and undetected butyric acid, whereas it was converse for 0.4% FA. The populations of enterobacteria, yeasts, moulds and aerobic bacteria were suppressed by 0.2% and 0.6% FA, resulting in lower dry matter loss, ammonia nitrogen and ethanol content (p<0.05). The increase of FA linearly (p<0.001) decreased neutral detergent fibre and hemicellulose, linearly (p<0.001) increased residual water soluble carbohydrate, glucose, fructose and xylose. The <i>in vitro</i> gas production of rice straw was decreased by ensilage but the initial gas production rate was increased, and further improved by FA application (p<0.05). No obvious difference of FA application on <i>in vitro</i> digestibility of dry matter, neutral detergent fibre, and acid detergent fibre was observed (p>0.05).Conclusion: The 0.2% FA application level promoted lactic acid fermentation while 0.6% FA restricted all microbial fermentation of rice straw silages. Rice straw ensiled with 0.2% FA or 0.6% FA improved its nutrient preservation without affecting digestion, with the 0.6% FA level best.

Novel cross‑switch seven‑level inverter with triple boost capability and self‑balancing

Jianxin Zhao,Yuanrui Chen,Jun Zeng,Lintao Wang,Junfeng Liu 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.9

A novel single-phase seven-level inverter using a cross-switch cell (CSC) is presented in this paper. Compared with conventional inverters, the proposed topology can generate seven-level output, triple boost gain with one dc source and a reduced number of switches. The CSC provides different charging paths for the capacitors to realize self-balance. Hence, the proposed inverter can realize self-balancing without additional control methods or sensors. Moreover, the proposed structure inherently generates negative output voltage levels without a back-end H-bridge circuit, which reduces the voltage stress on switches. This paper has fully illustrated the operation principles, and presents capacitance calculation and loss analysis. Afterward, a comparative study against recently proposed seven-level inverters is introduced, illustrating the merits of the proposed topology in terms of reduced switches, high voltage-boosting capacity, and self-balancing. Ultimately, a laboratory prototype is built for the validation of the proposed inverter.

Dynamic Characteristic Simulation of Helicopter Tail Drive Shaft System

Nie Junfeng,Yu Guangbin,Song Ye,Qu Zhigang,Zheng Minli,Zhao Xingfu 보안공학연구지원센터 2016 International Journal of Smart Home Vol.10 No.6

Helicopter with the advantage of light, flexible and hovering in the air, is widely used. In both military and civilian domain, it gets more and more attention. It becomes the main subject of research in the world. In the power transmission system of helicopter, the tail rotor shaft is an important part. It is one of the key technologies to predict the dynamic characteristics of the shaft accurately for improving the overall performance of the helicopter. Based on the theory of elastic mechanics, rotor dynamics and the finite element analysis, the former main drive shaft is taken as an example. The dynamic characteristics of the transmission shaft is calculated by the multi/few degrees of freedom finite element method. The validity of the finite element method with few degrees of freedom is determined. Then the structure characteristics of the helicopter tail drive shaft are analyzed, and the dynamic characteristics of the helicopter tail rotor shaft are calculated by using the finite element method with few degrees of freedom. The research results provide the basis and guidance for the design of the helicopter tail drive system.

Research on Nonlinear Vibration Characteristics of Spiral Bevel Gear

Nie Junfeng,Yu Guangbin,Song Ye,Qu Zhigang,Zheng Minli,Zhao Xingfu 보안공학연구지원센터 2016 International Journal of Multimedia and Ubiquitous Vol.11 No.2

Based on the concentrated parameters theory, a 7-freedom coupled vibration dynamic model of the spiral bevel gear transmission system is established, which includes transmission error, time-varying mesh stiffness and the tooth backlash clearance. In the model, the axial vibration, the torsion oscillation of the gear pair aroused by tooth meshing force and the lateral oscillations resulting from flexional deformation of the gear shaft are taken into account. The mesh stiffness fluctuation is developed as 5-order Fourier series and the tooth backlash clearance is fitted by 7-order polynomial function. Through the Gear method, the dynamic response of the system is obtained, and the vibration characteristics are analyzed.

Effects of lactic acid bacteria and molasses on fermentation dynamics, structural and nonstructural carbohydrate composition and in vitro ruminal fermentation of rice straw silage

Jie Zhao,Zhihao Dong,Junfeng Li,Lei Chen,Yunfeng Bai,Yushan Jia,Tao Shao 아세아·태평양축산학회 2019 Animal Bioscience Vol.32 No.6

Objective: This study was to evaluate the fermentation dynamics, structural and nonstructural carbohydrate composition and in vitro gas production of rice straw ensiled with lactic acid bacteria and molasses. Methods: Fresh rice straw was ensiled in 1-L laboratory silos with no additive control (C), Lactobacillus plantarum (L), molasses (M) and molasses+Lactobacillus plantarum (ML) for 6, 15, 30, and 60 days. After storage, the silages were subjected to microbial and chemical analyses as well as the further in vitro fermentation trial. Results: All additives increased lactic acid concentration, and reduced pH, dry matter (DM) loss and structural carbohydrate content relative to the control (p<0.05). The highest organic acid and residual sugar contents and lignocellulose reduction were observed in ML silage. L silage had the highest V-score with 88.10 followed by ML silage. L and ML silage improved in vitro DM digestibility as compared with other treatments, while in vitro neutral detergent fibre degradability (IVNDFD) was increased in M and ML silage (p<0.05). M silage significantly (p<0.05) increased propionic acid (PA) content and decreased butyric acid content and acetic acid/PA as well as 72-h cumulative gas production. Conclusion: The application of ML was effective for improving both the fermentation quality and in vitro digestibility of rice straw silage. Inclusion with molasses to rice straw could reduce in vitro ruminal gas production.

Aerodynamic modeling for streamlined box girders using nonlinear differential equations and validation in actively generated turbulence

Lin Zhao,Shengyuan Liu,Junfeng Yan,Yao-Jun Ge 한국풍공학회 2021 Wind and Structures, An International Journal (WAS Vol.33 No.1

In classical buffeting analysis theory, aerodynamic forces are usually expressed by a linear quasi-steady formula, and they are improved by aerodynamic admittances suitable for streamlined bridge girders. Recent studies have shown that admittances change obviously with incoming flow characteristics and aerodynamic nonlinearity, such as the frequency multiplication phenomenon, and motion-induced amplitude-related aerodynamic effects cannot be ignored in some cases. To address these problems, a nonlinear condensed subsystem equation (NCSE) suitable for wind-induced aerodynamic force modeling is established in the time domain. It characterizes aerodynamic nonlinearity with series of nonlinear differential equations and data-driven parameters. The proposed framework can be used for complex aerodynamic re-illustration related to the strong nonlinearity of streamlined box girders. To validate the precision and feasibility of the framework, sectional model experiments performed on a streamlined box girder were carried out in an active turbulence generated wind tunnel in which an adjustable array of multiple fans was assisted by actively controlled vibrating wings for a 2D turbulence condition. The case study shows that the NCSE model can be used to predict nonlinear aerodynamic forces in the time and frequency domains, even under complex stochastic flow conditions. The proposed method provides an alternative way to predict possible aerodynamics based on the condition of incoming flow with sufficient accuracy, and it can illustrate multifrequency components of aerodynamic forces.

Electronic Structure and Optical Properties of a Mn-Doped InSe/WSe2 van der Walls Heterostructure: First Principles Calculations

Liang Rundong,Zhao Xiuwen,Hu Guichao,Yue Weiwei,Yuan Xiaobo,Ren Junfeng 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.77 No.7

InSe-based van der Walls heterostructures (vdWHs) have attracted research interests recently because of their particular properties. In this work, the electronic structure and the optical properties of Mn-doped InSe/WSe2 vdWHs are investigated by using first-principles calculations. Mn doping in InSe/WSe2 vdWHs induces an increase in the system's band gap. The optical properties of the vdWHs are also studied, and the absorption intensity of Mn-doped InSe/WSe2 is found to be enhanced in the near-infrared and ultraviolet regions. In addition, built-in electric fields are generated in InSe/WSe2 and Mn-doped InSe/WSe2, which can inhibit recombination of photogenerated electron-hole pairs. This work predicates the feasibility of enhancing the optical properties in InSe/WSe2 vdWHs by introducing dopants, which extends the applications of InSe materials in the field of optoelectronics.

Measurement of the feedback coefficient by monitoring the power difference at power jump point in self-mixing vibration signal

Chenchen Wang,Junfeng Zhou,Yunkun Zhao,Youze Chen,Benli Yu,Liang Lu 한국물리학회 2019 Current Applied Physics Vol.19 No.4

This paper proposed a new method for measuring the feedback coefficient in the self-mixing interference. In experiment, the value of feedback coefficient is obtained by measuring the power difference at power jump point that based on the self-mixing vibration sensing system. It realized the measurement of feedback coefficient in range of 1–7.8 and shows a good agreement with the theoretical derivation and the corresponding simulation. Meanwhile, there is a good fitting result with the determination coefficient of 0.98 and line-width broadening factor of 3.245 respectively, which also realized measurement of feedback coefficient and line-width broadening factor at the same time.