Handling dependencies among performance shaping factors in SPAR-H through DEMATEL method

Xu Zhihui,Shang Shuwen,Su Xiaoyan,Qian Hong,Pan Xiaolei 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

The Standardized Plant Analysis Risk-Human Reliability Analysis (SPAR-H) method is a widely used method in human reliability analysis (HRA). Performance shaping factors (PSFs) refer to the factors that may influence human performance and are used to adjust nominal human error probabilities (HEPs) in SPAR-H. However, the PSFs are assumed to be independent, which is unrealistic and can lead to unreasonable estimation of HEPs. In this paper, a new method is proposed to handle the dependencies among PSFs in SPAR-H to obtain more reasonable results. Firstly, the dependencies among PSFs are analyzed by using decision-making trial and evaluation laboratory (DEMATEL) method. Then, PSFs are assigned different weights according to their dependent relationships. Finally, multipliers of PSFs are modified based on the relative weights of PSFs. A case study is illustrated that the proposed method is effective in handling the dependent PSFs in SPAR-H, where the duplicate calculations of the dependent part can be reduced. The proposed method can deal with a more general situation that PSFs are dependent, and can provide more reasonable results.

A GPU-based point kernel gamma dose rate computing code for virtual simulation in radiation-controlled area

Zhihui Xu,Mengkun Li,Bowen Zou,Ming Yang Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6

Virtual reality technology has been widely used in the field of nuclear and radiation safety, dose rate computing in virtual environment is essential for optimizing radiation protection and planning the work in radioactive-controlled area. Because the CPU-based gamma dose rate computing takes up a large amount of time and computing power for voxelization of volumetric radioactive source, it is inefficient and limited in its applied scope. This study is to develop an efficient gamma dose rate computing code and apply into fast virtual simulation. To improve the computing efficiency of the point kernel algorithm in the reference (Li et al., 2020), we design a GPU-based computing framework for taking full advantage of computing power of virtual engine, propose a novel voxelization algorithm of volumetric radioactive source. According to the framework, we develop the GPPK(GPU-based point kernel gamma dose rate computing) code using GPU programming, to realize the fast dose rate computing in virtual world. The test results show that the GPPK code is play and plug for different scenarios of virtual simulation, has a better performance than CPU-based gamma dose rate computing code, especially on the voxelization of three-dimensional (3D) model. The accuracy of dose rates from the proposed method is in the acceptable range.

MIGSHIELD: A new model-based interactive point kernel gamma ray shielding package for virtual environment

Li Mengkun,Xu Zhihui,Li Wei,Yang Jun,Yang Ming,Hongxin Lu,Dai Xinyu 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7

In this paper, 3D model-based interactive gamma ray shielding package (MIGSHIELD) is developed in virtual reality platform for windows operating system. In MIGSHIELD, the computational methodology is based on point kernel algorithm (PK), several key parameters of PK are obtained using new technique and new methods. MIGSHIELD has interactive capability with virtual world. The main features made in the MIGSHIELD are (i) handling of physical information from virtual world, (ii) handling of arbitrary shapes radioactive source, (iii) calculating the mean free path of gamma ray, (iv) providing interactive function between PK and virtual world, (v) making better use of PK for virtual simulation, (vi) plug and play. The developed package will be of immense use for calculations involving radiation dose assessment in nuclear safety and contributing to fast radiation simulation for virtual nuclear facilities.

Comments on the stability of the synchronous states of three vibrators in a vibrating system with two rigid frames

Xueliang Zhang,Zhihui Wang,Chao Li,Jinlin Xu 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.10

This paper focuses on the stability of three homodromy vibrators in a vibrating system with two rigid frames (RFs). The motion differential equations of the system are established. Using the average method yields the average coupling torque balanced equations of three vibrators, and the simplified analytical expressions for synchronization and stability criterions of the system were derived. The coupling dynamic characteristics were numerically analyzed, including frequency-amplitude response, stable phase differences, synchronization and stability ability, and phase relationships. The simulations to verify the validity of theoretical results were carried out. It is shown that the stable states of the system are classified into three types, thereof the stability of phase differences among vibrators is similar in sub-resonant and super-resonant states, which results in no vibration of the system. While in near sub-resonant state the system reflects strong useful positive superposition vibration with energy saving, which is exactly the desire in engineering design.

Long-term organic-inorganic fertilization ensures great soil productivity and bacterial diversity after natural-to-agricultural ecosystem conversion

Weibing Xun,Zhihui Xu,Wei Li,Yi Ren,Ting Huang,Wei Ran,Boren Wang,Qirong Shen,Ruifu Zhang 한국미생물학회 2016 The journal of microbiology Vol.54 No.9

Natural ecosystems comprise the planet’s wild plant and animal resources, but large tracts of land have been converted to agroecosystems to support the demand for agricultural products. This conversion limits the number of plant species and decreases the soil biological diversity. Here we used highthroughput 16S rRNA gene sequencing to evaluate the responses of soil bacterial communities in long-term converted and fertilized red soils (a type of Ferralic Cambisol). We observed that soil bacterial diversity was strongly affected by different types of fertilization management. Oligotrophic bacterial taxa demonstrated large relative abundances in chemically fertilized soil, whereas copiotrophic bacterial taxa were found in large relative abundances in organically fertilized and fallow management soils. Only organic-inorganic fertilization exhibited the same local taxonomic and phylogenetic diversity as that of a natural ecosystem. However, the independent use of organic or inorganic fertilizer reduced local taxonomic and phylogenetic diversity and caused biotic homogenization. This study demonstrated that the homogenization of bacterial communities caused by natural-to-agricultural ecosystem conversion can be mitigated by employing rational organic-inorganic fertilization management.

Effects of maternal dietary energy restriction on laying performance, embryonic development, and lipid metabolism in broilers

Sun, Hao,Chen, Zhihui,Ma, Chengzhan,Lian, Lina,Zhao, Zeyu,Niu, Shupeng,Xu, Liangmei,Sun, Jinhua Asian Australasian Association of Animal Productio 2022 Animal Bioscience Vol.35 No.5

Objective: The objective of this study was to investigate the effects of different degrees of maternal dietary energy restriction on lipid deposition in embryonic tissues during the medium laying period (37 to 39 weeks) in Arbor Acres (AA) broiler breeders. Methods: A single factor design was adopted, and 400 AA broiler breeders (20 weeks of age) with a similar weight were randomly allocated into four groups. The birds in the control group were fed a corn-soybean meal based diet, and those in trial groups were fed diets with 80%, 70%, and 50% energy levels of the basal diet. Incubated eggs from the medium laying period were collected. Samples of developing embryos at various stages were prepared for composition analysis. Results: The embryo weight in the 80% energy group was higher than those of the other groups on embryonic day (E) 13, but at 21 E, they were significantly decreased with decreasing energy intake of the broiler breeders (p<0.05). Additionally, the levels of crude fat in tissues in the restriction groups were significantly decreased (p<0.05). The long axis and area of adipocytes in breast muscle, thigh muscle and the liver were significantly decreased (p<0.05) at 21 E in the 80%, 70%, and 50% energy groups. Conclusion: The effects of the 80% maternal dietary energy restriction energy affects egg production performance, egg quality, and nutrient deposition in egg weights, which then directly impacts on the developmental process of embryos, especially on fat utilization and deposition.

Modified Asymmetrical Variable Step Size Incremental Conductance Maximum Power Point Tracking Method for Photovoltaic Systems

Yong Tian,Bizhong Xia,Zhihui Xu,Wei Sun 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

The power?voltage (P?V) characteristic of a photovoltaic (PV) array is nonlinear and time varying with the change in atmospheric conditions. As a result, the maximum power point tracking (MPPT) technique must be applied in PV systems to maximize the generated energy. The incremental conductance (INC) algorithm, one of the MPPT strategies, is widely used for its high tracking accuracy, good adaptability to rapidly changing atmospheric conditions, and easy implementation. This paper presents a modified asymmetrical variable step size INC MPPT method that is based on the asymmetrical feature of the P?V curve. Compared with conventional fixed or variable step size method, the proposed method can effectively improve tracking accuracy and speed. The theoretical foundation and design principle of the proposed approach are validated by the simulation and experimental results.

Modified Asymmetrical Variable Step Size Incremental Conductance Maximum Power Point Tracking Method for Photovoltaic Systems

Tian, Yong,Xia, Bizhong,Xu, Zhihui,Sun, Wei The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.1

The power-voltage (P-V) characteristic of a photovoltaic (PV) array is nonlinear and time varying with the change in atmospheric conditions. As a result, the maximum power point tracking (MPPT) technique must be applied in PV systems to maximize the generated energy. The incremental conductance (INC) algorithm, one of the MPPT strategies, is widely used for its high tracking accuracy, good adaptability to rapidly changing atmospheric conditions, and easy implementation. This paper presents a modified asymmetrical variable step size INC MPPT method that is based on the asymmetrical feature of the P-V curve. Compared with conventional fixed or variable step size method, the proposed method can effectively improve tracking accuracy and speed. The theoretical foundation and design principle of the proposed approach are validated by the simulation and experimental results.

Variation in limonin and nomilin content in citrus fruits of eight varieties determined by modified HPLC

Shengjia Huang,Xinya Liu,Bo Xiong,Xia Qiu,Guochao Sun,Xiaojia Wang,Xu Zhang,Zhixiang Dong,Zhihui Wang 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.3

The nomilin and limonin content in citrus fruitsof different varieties was determined at fruit growth andmaturation stages by HPLC. The results showed that thetwo limonoids can be separated, identified, and quantifiedin citrus fruits within 10 min by the developed method. Themethod exhibited good precision, repeatability, stability,and recovery rate. The content of limonin and nomilin inmost citrus fruits presented an increasing trend initially,and then decreased during fruit growth and maturation; apeak was observed at the young fruit or fruit expansionstage. The dropped fruits also contained some amount oflimonoids, suggesting their industrial application. Thevariation and cluster analyses results revealed that theorange varieties contained the highest amount of limonoidsat the mature stage. The results of this study will enablebetter use of citrus limonoids.