Isolation and Identification of Paracoccus sp. FD3 and Evaluation of Its Formaldehyde Degradation Kinetics

Haoyu Zhao,Yucong Geng,Jieyu Fan,Ke Tao,Taiping Hou 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.2

A formaldehyde-degrading bacterium strain,FD3, was isolated from contaminated soil and identified as Paracoccus sp. based on partial 16S rRNA gene sequence analysis. In batch culture, the bacterium metabolized 5,000and 8,000 mg/L formaldehyde completely within 16 and 18 h, respectively, at 30oC (pH 7.0) with agitation at 150 rpm. The degradation kinetics was found to follow a first-order model at all initial formaldehyde concentrations with regression values greater than 0.99. Formaldehyde degradation rates increased from 532.37 to 2283.04 mg/L/h as the initial concentration of formaldehyde was increased from 1,000 to 8,000 mg/L. The growth of strain FD3 on formaldehyde as a sole carbon and energy source was well described by the Luong model with a maximal specific growth rate of 0.1754/h, a half-saturation constant of 309.02 mg/L, and a maximum substrate concentration of 3875.53 mg/L. Due to its high tolerance and degradation capacity to formaldehyde, Paracoccus sp., FD3 is considered an excellent candidate for use in degrading formaldehyde in wastewaters.

Mechanical Properties of a Novel Modular Joint of Single-Layer Aluminium Alloy Lattice Shell

Caiqi Zhao,Yunwen Zhou,Gang Wang,Yating Wang,Haoyue Li 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3

To overcome the disadvantages of the discontinuous webs in the joint area of aluminium-alloy gusset joints and to further improve the efficiency of high-altitude positioning and installation of aluminium-alloy reticulated shell joints, this paper proposed a novel modular joint. Four sets of joint specimens were processed by computerized numerical control machine tools to carry out bearing capacity tests. The mechanical characteristics, failure mechanism and stiffness trends of this novel joint were explored. The results show that the proposed novel modular joints are significantly better than the traditional gusset joints in terms of bearing capacity and ductility. The flexural strength of the novel joints is 17% higher than that of the traditional gusset joints, and the novel joints have good deformability, which can prevent brittle failure. The results of elastoplastic finite element optimization analysis based on multiple contacts show that the theoretical failure mode and the curve of the load versus displacement of the joints are in good agreement with the actual measurements. Although the bearing capacity of the joints increases with increasing thickness of the modular unit and the reinforcement ring, when the thickness of the bottom plate exceeds twice the thickness of the top plate, this increase is very limited. Based on the working mechanism of the novel joints, a simplified calculation formula for their ultimate bearing capacity is proposed, which provides a theoretical basis for the engineering design and specification preparation of this type of joint henceforth.

A Novel Method of Phase-Shifted Full-Bridge Converter to Improve Efficiency under Light Load Condition

Lei Zhao,Haoyu Li,Yanxue Yu,Yutian Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

The main theme of this paper is to propose a novel peak current mode control method to reduce the loss of phase-shifted full-bridge (PSFB) converter under light load condition. The proposed control method can adjust the switching frequency of the converter to keep the on-time of switches fixed. According to the loss analysis model in discontinuous current mode operation, the switching frequency is proportional to load current and the efficiency is independent from the load. Moreover, the small signal model of the PSFB converter with the proposed control method is presented. A digital-controlled experimental system is set up. The proposed method is investigated and confirmed by experimental results. Experimental results show that the efficiency and dynamic performance can be improved. These results confirm the effectiveness of the proposed control method.

Interpersonal Relationship Matters: Commitment to Employees, Guanxi and Effectiveness of Strategy Implementation in Chinese SMEs

이장우,Haoyu Zhao 한국무역학회 2015 Journal of Korea trade Vol.19 No.4

The purpose of this study is to investigate whether the efforts firms make in maintaining interpersonal relationships have a positive influence on their performance. We examined the interpersonal relationships of a firm in two parts: (1) internal relationship - an organization’s commitment to its employees’ well-being (OCE) and (2) external relationship - managerial ties with the top executives of the other firms (business guanxi) and with government officials (political guanxi). More importantly, this study looked for whether OCE and guanxi would promote the profitable execution of competitive strategies (cost leadership, marketing differentiation and innovative differentiation). For this purpose, four hypotheses were developed and data was collected from 245 small and medium-size enterprises (SMEs) in a major industrial complex in China and analyzed with SPSS 20.0. The results were as follows: (1) OCE and guanxi both have a positive relationship with the financial and strategic performance of a firm. (2) The interaction between OCE and each different strategy showed different effects on a firm’s performance. Also, the interaction between guanxi and different strategies went the same way. This indicates that even though maintaining good interpersonal relationships would improve a Chinese SME’s performance, its importance and influence direction varies depending on which strategy is carried out. Such results suggest that business firms need to know the elaborate roles and meanings of interpersonal relationships in China.

Research on Dual-Operation Mode of 3-Level LLC Resonant Converter

A. Zhenwei Li,B. Lei Zhao,C. Yuan Liu,D. Haoyu Li 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In order to meet the demands of high efficiency and a wide adaptable range of input voltage, a Dual- Operation Mode half-bridge LLC converter which can operate in two different modes according to the level of input voltage is obtained by adjusting the driving control strategy of 3-level LLC resonant converter, and the adaptable range of input voltage is doubled with the same parameters of resonant tank. The limiting factors on adaptable range of input voltage are defined by analyzing the voltage gain characteristic and power loss of LLC converter. After analyzing the Dual-Operation Mode of 3- level LLC converter and its influence on the adaptable range of input voltage, the driving control strategy is defined. The characteristic about wide input adaptability and high efficiency of the Dual-Operation Mode half-bridge LLC converter are verified through simulation and experiments.

Conceptual design of a dual drum-controlled space molten salt reactor (D² -SMSR): Neutron physics and thermal hydraulics

Yongnian Song,Nailiang Zhuang,Hangbin Zhao,Chen Ji,Haoyue Deng,Xiaobin Tang Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

Space nuclear reactors are becoming popular in deep space exploration owing to their advantages of high-power density and stability. Following the fourth-generation nuclear reactor technology, a conceptual design of the dual drum-controlled space molten salt reactor (D²-SMSR) is proposed. The reactor concept uses molten salt as fuel and heat pipes for cooling. A new reactivity control strategy that combines control drums and safety drums was adopted. Critical physical characteristics such as neutron energy spectrum, neutron flux distribution, power distribution and burnup depth were calculated. Flow and heat transfer characteristics such as natural convection, velocity and temperature distribution of the D²-SMSR under low gravity conditions were analyzed. The reactivity control effect of the dual-drums strategy was evaluated. Results showed that the D²-SMSR with a fast spectrum could operate for 10 years at the full power of 40 kWth. The D²-SMSR has a high heat transfer coefficient between molten salt and heat pipe, which means that the core has a good heat-exchange performance. The new reactivity control strategy can achieve shutdown with one safety drum or three control drums, ensuring high-security standards. The present study can provide a theoretical reference for the design of space nuclear reactors.