Comparison of the Radiation Shielding Properties of Wall Materials for the Manned Spacecraft for Future China Space Exploration Missions

Huibin Sun,Zhengxin Wu,Yugang Ma,Jinbin Lu,Guoqing Liu,Haige Zhao,Yin Wang,Yanqi Hu 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.75 No.9

The radiation environment in space poses signicant challenges to human health, and it is a ma- jor concern in long duration, manned space missions. Outside Earth's protective magnetosphere, astronauts are exposed to higher levels of galactic cosmic rays (GCRs), whose physical character- istics are distinct from those of terrestrial sources of radiation, such as X-rays and gamma-rays. GCRs include high-energy heavy ions, many of which have ranges that exceed the depth of shielding and can be launched in realistic scenarios. Protecting the astronauts from these particles has been a key issue in manned space missions. Therefore, a need exists for reliable simulations of these harmful effects for risk assessment and shielding optimization in manned space missions. The aim of this work was to investigate shielding materials that can be used in deep space and planetary exploration. In this work, we used the Geant4 radiation transport code, originally developed by the International Geant4 Collaboration, and we compared the radiation shielding effectivenesses of polyethylene, aluminum, water, and carbon ber targets hit by 1GeV/nucleon 56Fe (considered as a representative of high-energy GCR). In addition, the total absorbed doses at the water phantom behind these targets were calculated using the Geant4 simulation code. The calculated results were analyzed, compared, and discussed. The results show that polyethylene is the best space radiation shielding material for a given areal density, followed by water, carbon ber, and then aluminum.

MGGC2.0: A preprocessing code for the multi-group cross section of the fast reactor with ultrafine group library

Hu Kui,Ma Xubo,Zhang Teng,Ma Xuan,Huang Zifeng,Chen Yixue 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.8

How to generate the precise broad group cross section is important for the fast reactor design. In this study, a fast reactor multi-group cross-section generation code MGGC2.0 are developed in-house for processing ultrafine group MATXS format library. Validation and verification are performed for MGGC2.0 code by applying the benchmarks of ICSBEP handbook, and the results of MGGC2.0 agree well with that of MCNP. The consistent PN method with critical buckling search is in good agreement that condensed with TWODANT flux and flux moment for the inner core and outer core region. For the radial blanket and reflector, two region approximation method has been applied in MGGC2.0 by using collision Probability Method neutron flux solver. The RBEC-M benchmark was used to verify the power distribution calculation, and the relative error of power distribution comparison with the reference are less than 0.8% in the fuel region and the maximum relative error is 5.58% in the reflector region. Therefore, the precise broad cross section can be generated by MGGC2.0 for fast reactor

Energy-saving Methods in the Operation of Virtual Networks Based on Divided Time Slices

HU Ying,ZHUANG Lei,HU Yu-xiang,MA Ding 보안공학연구지원센터 2016 International Journal of Grid and Distributed Comp Vol.9 No.7

Reducing energy consumption has also become an important way to reduce expenditures and increase revenue for ISP. For solving the problem of dynamically changing network-flow of virtual network in runtime, we first analyze relations and differences between virtual network and IP network on energy-saving issues. We secondly model the makeup of energy consumption in virtual network, and determine the object of energy-saving in virtual network at. Finally we propose the solutions to this energy-saving problem. The solutions can be described as follows: (1) based on the historical data of daily network-flow, we divide one day into two time slices, and one is called idle time slice, the other is called busy time slice; (2) we design the dynamic switch-off algorithm and run it at the beginning of idle time slice, and we use former algorithms to be started at the beginning of busy time slice; (3) in the dynamic switch-off algorithm we determine the method to select virtual networks and the method to remap; (4) we apply roulette wheel to select virtual networks, in the selection method we consider both current influences on energy-saving and influences in the future. Simulation results show that the dynamic switch-off algorithm can effectively select virtual networks, and the whole solution performs well in energy aware virtual network in runtime.

Hardware Design of Low Energy Consumption Wireless Senor Network Node for Monitoring Mechanical Vibration Signals

Ma Naji,Diao Ming,Hu Xiao,Sun Jian,Ma Anchang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.5

Aiming at the increasing demand of the monitoring of mechanical vibration signals, by improving the existing Sensor Monitoring Network, a low-power wireless sensor network is designed. The data transmission efficiency is increased by using the compressed sensing (CS) technology to compress the mechanical vibration signals of the devices monitored by the network. To realize real-time processing of monitoring signals, the FPGA+DSP architecture is treated as the core of the equipment processing the mechanical vibration signals of wireless sensor network. The modified designs of the hardware circuit and logic circuit with regard to the data collection, sampling, transmission, processing and the store section are introduced initially. Further, the effects of the improved Sensor Monitoring Network are tested by the experimental study on the rotating equipment. The results show that the real-time processing can be well implemented and the power can be cut down to a certain degree.

DRAG REDUCTION PREDICTION OF AHMED MODEL WITH TRAVELING WAVE BASED ON BP NEURAL NETWORK

Hu Xingjun Hu,Jinglong Zhang,Yufei Luo,Jingyu Wang,Pengzhan Ma,Wei Lan,Chunbo Dong 한국자동차공학회 2022 International journal of automotive technology Vol.23 No.5

In this paper, a traveling wave model is proposed to explore its influence on the aerodynamic drag of a Ahmed model, the experimental and numerical results of aerodynamic drag coefficient CD for the Ahmed model are in good agreement. Then by defining the aerodynamic benefit coefficient ΔCD as the evaluation index for the orthogonal experiment, range analysis is conducted to determine the influences of the amplitude A, wavelength λ and frequency ω of the wave and the vehicle speed u on ΔCD. After the analysis it can been found that λ has the least importance among these parameters, hence A, ω and u are used to construct the 105 samples for training the BP neural network to predict ΔCD, results show that ΔCD obtained from the neural network is significantly affected by the parameters of traveling wave. The prediction accuracy of the network is furtherly verified by another 15 samples which are also built on A, ω and u, and the corresponding data overlap rate of ΔCD is 96 %, so it can be concluded that the BP neural network constructed in this paper is accurate enough to predict ΔCD.

Modeling, Testing and Numerical Simulation on Hot Forming of HSS

Ning Ma Ping Hu,Guozhe Shen Wenhua Wu 한국소성가공학회 2010 기타자료 Vol.2010 No.6

The thermal-mechanical-transformation coupled relationship of microalloy steel has important significance in forming mechanism and numerical simulation of hot forming. Tensile and quenching experiments are implemented at high temperature, and then the thermal-mechanical-transformation coupled constitutive models of hot forming are developed. Based these models, the nonlinear large-deformation dynamic explicit finite element equations are proposed. The phase transformation latent heat is introduced into the analysis of temperature field during the hot forming process. Based on the independently developed commercial CAE software for sheet metal forming, named KMAS (King-Mesh Analysis System), the numerical simulation module of hot forming is developed, which considers multi-field coupled models, nonlinear and large deformation analysis. Then the hot forming process of a reinforced beam inside the automobile door is simulated by the KMAS software, and compared with its hot forming experimental testing. The experimental results indicate the validity and efficiency of the present multi-field coupled constitutive models and numerical simulation software KMAS of hot forming.

Suction Effect of a Vertical Coated Plain Porous Layer on Film Condensation Heat Transfer Enhancement

Xue Hu Ma,Bu Xuan Wang 대한기계학회 1998 Heat transter conference Vol.5 No.1

Design of Multi-Channel Wireless Sensor Networks Based On Compressive Sensing Theory and Spectrum Sensing Theory

Naji Ma,Ming Diao,Xiao Hu,Jian Sun,Anchang Ma 보안공학연구지원센터 2015 International Journal of Smart Home Vol.9 No.9

The single-channel wireless sensor networks (WSNs) exists the problem of low efficiency of monitoring data transmission, however the multi-channel WSNs exists the problem of communication collision caused by the sensor node’s wireless channel competition. The paper at first introduces the causes of the above problems and selects a reasonable wireless channel resources allocation method of the multi-channel WSNs. Then to solve these questions, the theory of compressive sensing and spectrum sensing are adopted to improve the existing multi-channel WSNs. Finally, a new sensor node of the multi-channel WSNs is designed based on the above improvement. By analyzing the monitoring data of the field test, the improved multi-channel WSNs could complete monitoring mission efficiently and accurately, meanwhile it reduced power consumption of the WSNs effectively.

Purification and Characterization of an Extracellular Protease from Bacillus pumilus CN8

Mei-Hu Ma,Yong-Guo Jin,Hao-Li Li,Jun Wang,Ha-Na Kim,오덕환 한국식품위생안전성학회 2011 한국식품위생안전성학회지 Vol.26 No.1

The protease produced by a Bacillus pumilus CN8 strain was purified by DEAE-Cellulose-52 ion exchange. It has a molecular weight of approximately 96,920 Dalton. In the present study, this protease showed strong activity over a broad range of pH (6.5-9.5) and temperature from 40℃ to 60℃, and the protease performed the maximal activity at pH 7.3 at 42℃. The effect of metal ions on protease activity showed that K+ could slightly increase the protease activity, and other ions such as Zn²+, Fe²+, Na+, Ca²+, Mg²+ had no significant activation or inhibition to the protease (P > 0.05), and the more important is that Cu²+, Mn²+, Sn²+, Cd²+ had a strong inhibitory effect on the protease activity.

The Novel Pathogenic Mutation c.849dupT in BRCA2 Contributes to the Nonsense-Mediated mRNA Decay of BRCA2 in Familial Breast Cancer

Sanrong Li,Jing Ma,Caiying Hu,Xing Zhang,Deyong Xiao,Lili Hao,Wenjun Xiao,Jichun Yang,Ling Hu,Xiaowei Liu,Minghui Dong,Duan Ma,Rensheng Liu 한국유방암학회 2018 Journal of breast cancer Vol.21 No.3

In this study, we used next-generation sequencing methods to screen 300 individuals for BRCA1 and BRCA2. A novel mutation (c.849dupT) in BRCA2 was identified in a female patient and her unaffected brothers. This mutation leads to the truncation of BRCA2 functional domains. Moreover, BRCA2 mRNA expression levels in mutation carriers are significantly reduced compared to noncarriers. Immunofluorescence and western blot assays showed that this mutation resulted in reduced BRCA2 protein expression. Thus, we identified a novel mutation that damaged the function and expression of BRCA2 in a family with breast cancer history. The pedigree analysis suggested that this mutation is strongly associated with familial breast cancer. Genetic counsellors suggest that mutation carriers in this family undergo routine screening for breast cancer, as well as other malignancies, such as prostate and ovarian cancer. The effects of this BRCA2 mutation on drug resistance should be taken into consideration during treatment.