Evaluation of High Butanol/Acetone Ratios in ABE Fermentations with Cassava by Graph Theory and NADH Regeneration Analysis

Zhigang Li,Zhongping Shi,Xin Li,Le Li,Junping Zheng,Zhenggang Wang 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.4

Higher butanol/acetone ratio is always desirable in ABE fermentation, and this ratio is closely associated with the complicated patterns of metabolic reactions and NADH generation rate. The patterns of acetate/butyrate formation and re-assimilation in multiple closed reaction loops, as well as NADH regeneration in ABE fermentation using different substrates varies. In this study, we evaluated butanol/acetone ratio in ABE fermentations utilizing cassava and corn based media by graph theory and NADH regeneration analysis. The theoretical calculations and experimental data revealed that a lower metabolic strength in butyrate loop and enhanced NADH generation rate were responsible for the achievement of higher butanol/acetone ratio when fermenting cassava based substrate. In traditional fermentations and extractive fermentations with oleyl alcohol/bio-diesel as the extractants when using cassava based substrate, butanol/acetone ratios reached 2.24, 2.84,and 2.19 with the increasing increments of 14.9, 61.4, and 6.8% respectively, while butanol productivities stayed at comparably high levels as compared with those of the fermentations when cultivating on corn based substrate.

Development and verification of PWR core transient coupling calculation software

Li, Zhigang,An, Ping,Zhao, Wenbo,Liu, Wei,He, Tao,Lu, Wei,Li, Qing Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.11

In PWR three-dimensional transient coupling calculation software CORCA-K, the nodal Green's function method and diagonal implicit Runge Kutta method are used to solve the spatiotemporal neutron dynamic diffusion equation, and the single-phase closed channel model and one-dimensional cylindrical heat conduction transient model are used to calculate the coolant temperature and fuel temperature. The LMW, NEACRP and PWR MOX/UO₂ benchmarks and FangJiaShan (FJS) nuclear power plant (NPP) transient control rod move cases are used to verify the CORCA-K. The effects of burnup, fuel effective temperature and ejection rate on the control rod ejection process of PWR are analyzed. The conclusions are as follows: (1) core relative power and fuel Doppler temperature are in good agreement with the results of benchmark and ADPRES, and the deviation between with the reference results is within 3.0% in LMW and NEACRP benchmarks; 2) the variation trend of FJS NPP core transient parameters is consistent with the results of SMART and ADPRES. And the core relative power is in better agreement with the SMART when weighting coefficient is 0.7. Compared with SMART, the maximum deviation is -5.08% in the rod ejection condition and while -5.09% in the control rod complex movement condition.

Ratio of PM2.5 to PM10 Mass Concentrations in Beijing and Relationships with Pollution from the North China Plain

Zhigang Li,Xin Yang,Chuanfeng Zhao,Tianyi Fan 한국기상학회 2021 Asia-Pacific Journal of Atmospheric Sciences Vol.57 No.3

Five years of PM2.5/PM10 ratios and their potential relationships with wind and relative humidity (RH) were analyzed for three areas in Beijing (northwestern mountainous area, urban area and southern suburbs), and these values were compared with those of five other cities, including Tianjin, Dalian, Hangzhou, Shanghai and Guangzhou. In the past five years, both PM2.5 and PM10 mass concentrations have decreased over the three Beijing regions, particularly during winters. The PM2.5/PM10 ratios have distinct seasonal characteristics, with more frequent high ratios in winter than in other seasons. The high ratio frequency decrease is most evident in winter and in the southern Beijing suburbs. This fine particle proportion decrease is related to air pollution control policies, including the national project ‘Coal to Gas’. HighPM2.5/PM10 ratios are linked to heavy pollution levels and low wind speeds, indicating the importance of PM2.5 accumulation during pollution events in Beijing. The higher PM2.5/PM10 ratios in Beijing are also closely related to southerly winds and high humidity, indicating the contribution of anthropogenic pollution transported from the south. Due to similar geographic environments, Tianjin is similar to Beijing in terms of the frequency distribution characteristics of the PM2.5/PM10 ratios. The coastal city of Dalian is further north and not similar to Beijing or Tianjin, owing to a sea breeze influence. Different from Beijing and Tianjin, the southern cities of Hangzhou, Shanghai and Guangzhou show almost no change in the PM2.5/PM10 ratio frequency distribution with increases in wind speed and relative humidity.

Static Detection of False Data in the Power Grid by Fusing Structure and Attributes of Node

Li Xueping,Li Xuanxuan,Lu Zhigang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

False data injection attack can evade the traditional state estimation in the power system, resulting in the historical data may have been polluted. Under such circumstances, the contaminated historical data cannot provide the priori data, so data-driven detection cannot be carried out. Hence, this paper proposes a static detection method of false data based on the similarity characteristics of network nodes at a certain time, where structure and attributes of nodes are fused to express nodes based on the egonet model of power grid. In addition, to improve the accuracy of clustering, the detection rate is adopted in the clustering method. The method is tested in IEEE118-bus and 2383-bus systems. The simulation results show that proposed method is effective, and can detect the possible false data injection problems in the power system over 80%.

Exploring the Influence of Vehicle Mobility on Information Spreading in VANETs

( Zhigang Li ),( Xin Wang ),( Xinan Yue ),( Yingli Ji ),( Hua Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.2

With the advent of 5G communications, internet of vehicles technology has been widely used in vehicles. Then the dynamic spread of information between vehicles began to come into focus with more research. It is well known that the identification of nodes with great spread influence has always been a hot topic in the field of information spreading. Most of the existing work measures the propagation influence by degree centrality, betweenness centrality and closeness centrality. In this paper, we will identify influential vehicle nodes based on the mobility characteristics of vehicles to explore the information spreading between vehicles in VANETs. Different from the above methods, we mainly explore the influence of the radius of gyration and vehicle kilometers of travel on information spreading. We use a real vehicle trajectory data to simulate the information transmission process between vehicles based on the susceptible-infected-recovered SIR model. The experimental results show that the influence of information spreading does not enhance with increasing radius of gyration and vehicle kilometers of travel. The fact is that both the radius of gyration and the distance travelled have a significant influence on information spreading when they are close to the median. When the value of both is large or small, it has little influence on information spreading. In view of this results, we can use the radius of gyration and vehicle kilometers of travel to better facilitate the transmission of information between vehicles.

Verification of neutronics and thermal-hydraulic coupled system with pin-by-pin calculation for PWR core

Li Zhigang,Pan Junjie,Xia Bangyang,Qiang Shenglong,Lu Wei,Li Qing 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9

As an important part of the digital reactor, the pin-by-pin wise fine coupling calculation is a research hotspot in the field of nuclear engineering in recent years. It provides more precise and realistic simulation results for reactor design, operation and safety evaluation. CORCA-K a nodal code is redeveloped as a robust pin-by-pin wise neutronics and thermal-hydraulic coupled calculation code for pressurized water reactor (PWR) core. The nodal green's function method (NGFM) is used to solve the threedimensional space-time neutron dynamics equation, and the single-phase single channel model and one-dimensional heat conduction model are used to solve the fluid field and fuel temperature field. The mesh scale of reactor core simulation is raised from the nodal-wise to the pin-wise. It is verified by two benchmarks: NEACRP 3D PWR and PWR MOX/UO2. The results show that: 1) the pin-by-pin wise coupling calculation system has good accuracy and can accurately simulate the key parameters in steadystate and transient coupling conditions, which is in good agreement with the reference results; 2) Compared with the nodal-wise coupling calculation, the pin-by-pin wise coupling calculation improves the fuel peak temperature, the range of power distribution is expanded, and the lower limit is reduced more

Cellular Traffic Offloading through Opportunistic Communications Based on Human Mobility

( Zhigang Li ),( Yan Shi ),( Shanzhi Chen ),( Jingwen Zhao ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.3

The rapid increase of smart mobile devices and mobile applications has led to explosive growth of data traffic in cellular network. Offloading data traffic becomes one of the most urgent technical problems. Recent work has proposed to exploit opportunistic communications to offload cellular traffic for mobile data dissemination services, especially for accepting large delayed data. The basic idea is to deliver the data to only part of subscribers (called target-nodes) via the cellular network, and allow target-nodes to disseminate the data through opportunistic communications. Human mobility shows temporal and spatial characteristics and predictability, which can be used as effective guidance efficient opportunistic communication. Therefore, based on the regularity of human mobility we propose NodeRank algorithm which uses the encounter characteristics between nodes to choose target nodes. Different from the existing work which only using encounter frequency, NodeRank algorithm combined the contact time and inter-contact time meanwhile to ensure integrity and availability of message delivery. The simulation results based on real-world mobility traces show the performance advantages of NodeRank in offloading efficiency and network redundant copies.

<i>OsASR5</i> enhances drought tolerance through a stomatal closure pathway associated with ABA and H ₂ O ₂ signalling in rice

Li, Jinjie,Li, Yang,Yin, Zhigang,Jiang, Jihong,Zhang, Minghui,Guo, Xiao,Ye, Zhujia,Zhao, Yan,Xiong, Haiyan,Zhang, Zhanying,Shao, Yujie,Jiang, Conghui,Zhang, Hongliang,An, Gynheung,Paek, Nam‐,Cho John Wiley and Sons Inc. 2017 Plant biotechnology journal Vol.15 No.2

<P><B>Summary</B></P><P>Drought is one of the major abiotic stresses that directly implicate plant growth and crop productivity. Although many genes in response to drought stress have been identified, genetic improvement to drought resistance especially in food crops is showing relatively slow progress worldwide. Here, we reported the isolation of <I>abscisic acid</I>,<I> stress</I> and <I>ripening</I> (<I>ASR</I>) genes from upland rice variety, IRAT109 (<I>Oryza sativa</I> L. ssp. <I>japonica</I>), and demonstrated that overexpression of <I>OsASR5</I> enhanced osmotic tolerance in <I>Escherichia coli</I> and drought tolerance in <I>Arabidopsis</I> and rice by regulating leaf water status under drought stress conditions. Moreover, overexpression of <I>OsASR5</I> in rice increased endogenous ABA level and showed hypersensitive to exogenous ABA treatment at both germination and postgermination stages. The production of H<SUB>2</SUB>O<SUB>2</SUB>, a second messenger for the induction of stomatal closure in response to ABA, was activated in overexpression plants under drought stress conditions, consequently, increased stomatal closure and decreased stomatal conductance. In contrast, the loss‐of‐function mutant, <I>osasr5</I>, showed sensitivity to drought stress with lower relative water content under drought stress conditions. Further studies demonstrated that OsASR5 functioned as chaperone‐like protein and interacted with stress‐related HSP40 and 2OG‐Fe (II) oxygenase domain containing proteins in yeast and plants. Taken together, we suggest that <I>OsASR5</I> plays multiple roles in response to drought stress by regulating ABA biosynthesis, promoting stomatal closure, as well as acting as chaperone‐like protein that possibly prevents drought stress‐related proteins from inactivation.</P>

Temporal and Spatial Traffic Analysis Based on Human Mobility for Energy Efficient Cellular Network

( Zhigang Li ),( Xin Wang ),( Junsong Zhang ),( Wei Huang ),( Ye Tian ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.1

With the drastic growth of Information and Communication Technology (ICT) industry, global energy consumption is exponentially increased by mobile communications. The huge energy consumption and increased environmental awareness have triggered great interests on the research of dynamic distribution of cell user and traffic, and then designing the energy efficient cellular network. In this paper, we explore the temporal and spatial characteristics of human mobility and traffic distribution using real data set. The analysis results of cell traffic illustrate the tidal effect in temporal and spatial dimensions and obvious periodic characteristics which can be used to design Base Station (BS) dynamic with sleeping or shut-down strategy. At the same time, we designed a new Cell Zooming and BS cooperation mode. Through simulation experiments, we found that running in this mode can save about 35% of energy consumption and guarantee the required quality of service.

Research on Relay Selection Technology Based on Regular Hexagon Region Segmentation in C-V2X

Zhigang Li,Xinan Yue,Xin Wang,Baozhu Li,Daoying Huang 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.9

Traffic safety and congestion are becoming more and more serious, especially the frequent occurrence of traffic accidents, which have caused great casualties and economic losses. Cellular Vehicle to Everything (C-V2X) can assist in safe driving and improve traffic efficiency through real-time information sharing and communication between vehicles. All vehicles communicate directly with Base Stations (BS), which will increase the base station load. And when the communicating vehicles are too far apart, too fast or there are obstacles in the communication path, the communication link can be unstable or even interrupted. Therefore, choosing an effective and reliable multi-hop relay-assisted Vehicle to Vehicle (V2V) communication can not only reduce the base station load and improve the system throughput but also expand the base station coverage and improve the communication quality of edge vehicles. Therefore, a communication area division scheme based on regular hexagon segmentation technology is proposed, a relay-assisted V2V communication mechanism is designed for the divided communication areas, and an efficient communication link is constructed by selecting the best relay node. Simulation results show that the scheme can improve the throughput of the system by nearly 55% and enhance the robustness of the V2V communication link.