Methodology of uncertainty analysis prediction based on multi-well data fusion

Huan Jie Zhang,Kai Wei,Alain P. Tchameni,G. Ben-Kane 한국자원공학회 2018 Geosystem engineering Vol.21 No.3

During drilling activities, geological parameters of a well to be drilled (target well) can be predicted within a limited interval based on multi-well data fusion which aims at ensuring a drilling safety, enhancement of drilling efficiency, reduction of drilling cost as well as acquiring accurate measurements in respect to Oil and Gas protection layers. This work presents a method of uncertainty analysis prediction of pressures using fusion data (formation pressures) from adjacent multi-well. The Eaton method, effective stress theory, and mathematical confidence interval were the various methods used to establish the formation pressure matrix of the target well. The results revealed that due to the complexity and variability of the formations, data interpretation errors of the geological parameters were inevitable. Therefore, the probability density distribution function was established through stratigraphy, probability statistics, and information diffusion. Moreover, the real value of the wells’ formation pressure (target well) was within the distribution interval of multi-well data fusion. Hence, the developed method cannot only effectively reduce the interval of geological parameter of the target well but also enhance the accuracy of parameters prediction.

Risk Factors for Cervical Cancer in Rural Areas of Wuhan China: a Matched Case-control Study

Zhang, Bin,Zhou, Ai-Fen,Zhu, Chang-Cai,Zhang, Ling,Xiang, Bing,Chen, Zhong,Hu, Rong-Hua,Zhang, Ya-Qi,Qiu, Lin,Zhang, Yi-Ming,Xiong, Chao-Du,Du, Yu-Kai,Shi, Yu-Qin Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.12

Cervical cancer is a serious public health problem in developing countries. We investigated possible risk factors for cervical cancer in rural areas of Wuhan China using a matched case-control study with 33 women diagnosed with cervical cancer and 132 healthy women selected from the same area as matched controls. A questionnaire, which included questions about general demography conditions, environmental and genetic factors, the first sexual intercourse, first marriage age, age at first pregnancy, pregnancy first child's age, female personal health history, social psychological factors, dietary habits, smoking and alcohol status and other living habits was presented to all participants. At the same time, HPV infection of every participant was examined in laboratory testing. Results showed HPV infection (P<0.000, OR=23.4) and pregnancy first child's age (P<0.000, OR=13.1) to be risk factors for cervical cancer. Menopause (P=0.003, OR=0.073) was a protective factor against cervical cancer. However, there was no indication of associations of environmental (drinking water, insecticide, disinfectant) genetic (cancer family history), or life-style factors (smoking status, alcohol status, physical training, sleep quality), including dietary habits (intake of fruit and vegetable, meat, fried food, bean products and pickled food) or social psychological factors with cervical cancer. The results suggest that the risk of cervical cancer in Chinese rural women may be associated with HPV infection, menopause and the pregnancy first child's age.

Impact of numerical choices on water conservation in the E3SM Atmosphere Model version 1 (EAMv1)

Zhang, Kai,Rasch, Philip J.,Taylor, Mark A.,Wan, Hui,Leung, Ruby,Ma, Po-Lun,Golaz, Jean-Christophe,Wolfe, Jon,Lin, Wuyin,Singh, Balwinder,Burrows, Susannah,Yoon, Jin-Ho,Wang, Hailong,Qian, Yun,Tang, Q Copernicus GmbH 2018 Geoscientific model development Vol.11 No.5

<P><p><strong>Abstract.</strong> The conservation of total water is an important numerical feature for global Earth system models. Even small conservation problems in the water budget can lead to systematic errors in century-long simulations. This study quantifies and reduces various sources of water conservation error in the atmosphere component of the Energy Exascale Earth System Model.</p> <p>Several sources of water conservation error have been identified during the development of the version 1 (V1) model. The largest errors result from the numerical coupling between the resolved dynamics and the parameterized sub-grid physics. A hybrid coupling using different methods for fluid dynamics and tracer transport provides a reduction of water conservation error by a factor of 50 at 1<span class='inline-formula'>^∘</span> horizontal resolution as well as consistent improvements at other resolutions. The second largest error source is the use of an overly simplified relationship between the surface moisture flux and latent heat flux at the interface between the host model and the turbulence parameterization. This error can be prevented by applying the same (correct) relationship throughout the entire model. Two additional types of conservation error that result from correcting the surface moisture flux and clipping negative water concentrations can be avoided by using mass-conserving fixers. With all four error sources addressed, the water conservation error in the V1 model becomes negligible and insensitive to the horizontal resolution. The associated changes in the long-term statistics of the main atmospheric features are small.</p> <p>A sensitivity analysis is carried out to show that the magnitudes of the conservation errors in early V1 versions decrease strongly with temporal resolution but increase with horizontal resolution. The increased vertical resolution in V1 results in a very thin model layer at the Earth's surface, which amplifies the conservation error associated with the surface moisture flux correction. We note that for some of the identified error sources, the proposed fixers are remedies rather than solutions to the problems at their roots. Future improvements in time integration would be beneficial for V1.</p> </P>

Adaptive Dynamic Programming for Minimal Energy Control with Guaranteed Convergence Rate of Linear Systems

Kai Zhang,Suoliang Ge,Yuling Ge 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.12

The traditional linear quadratic optimal control can be summarized as finding the state feedback controller, so that the closed-loop system is stable and the performance index is minimum. And it is well known that the solution of the linear quadratic optimal control problem can be obtained by algebraic Riccati equation (ARE) with the standard assumptions. However, results developed for the raditional linear quadratic optimal control problem cannot be directly applied to solve the problem of minimal energy control with guaranteed convergence rate (MECGCR), because the standard assumptions cannot be satisfied in the MECGCR problem. In this paper, we mainly consider the problem of MECGCR and prove that ARE can be applied to solve the MECGCR problem under some conditions. Furthermore, with the assumption that the system dynamics is unknown, we propose a policy iteration (PI) based adaptive dynamic programming (ADP) algorithm to iteratively solve the ARE using the online information of state and input, without requiring the a priori knowledge of the system matrices. Finally, a numerical example is worked out to show the effectiveness of the proposed approach.

Bifunctional Conducting Polymer Coated CoP Core-Shell Nanowires on Carbon Paper as a Free-Standing Anode for Sodium Ion Batteries

Zhang, Jing,Zhang, Kai,Yang, Junghoon,Lee, Gi-Hyeok,Shin, Jeongyim,Wing-hei Lau, Vincent,Kang, Yong-Mook Wiley (John WileySons) 2018 Advanced energy materials Vol.8 No.20

CK2 phosphorylates AP-2α and increases its transcriptional activity

( Kai Qun Ren ),( Shuang Lin Xiang ),( Fang Li He ),( Wen Feng Zhang ),( Xiao Feng Ding ),( Yan Yang Wu ),( Li Ping Yang ),( Jian Lin Zhou ),( Xiang Gao ),( Jian Zhang ) 생화학분자생물학회(구 한국생화학분자생물학회) 2011 BMB Reports Vol.44 No.7

Transcription factor AP-2α involves in the process of mammalian embryonic development and tumorigenesis. Many studies have shown that AP-2α functions in association with other interacting proteins. In a two-hybrid screening, the regulatory subunit β of protein casein kinase 2 (CK2β) was identified as an interacting protein of AP-2α; we confirmed this interaction using in-vitro GST pull-down and in-vivo co-immunoprecipitation assays; in an endogenous co-immunoprecipitation experiment, we further found the catalytic subunit α of protein casein kinase 2 (CK2α) also exists in the complex. Phosphorylation analysis revealed that AP-2α was phosphorylated by CK2 kinase majorly at the site of Ser429, and such phosphorylation could be blocked by CK2 specific inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB) in a dose-dependent manner. Luciferase assays demonstrated that both CK2α and CK2β enhanced the transcription activity of AP-2α; moreover, CK2β increased the stability of AP-2α. Our data suggest a novel cellular function of CK-2 as a transcriptional co-activator of AP-2α.

Analysis Method based on Rough Attack-defense Bayes Game Model

Kai Zhang 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.1

In order to solve the strategic interdependence question during the attack and defense process in a complex network, the dissertation proposes an analysis method based on rough attack-defense Bayes game model. After defining the inner structure of attacking agent and defense agent, the dissertation extends traditional object Petri Net and introduces rough set theory into node domain and transition domain, then propose the network attack-defense confrontation model. By dividing domain attack strategy set into equivalence classes, the extraction method of characteristic attack strategy set is given. Then the rough game model and utility function of attack and defense agents are defined, accordingly, the solution of Bayes equilibrium strategy and maximal attack and defense strategy set are proposed. The analysis method can reduce the scale of strategic space of the game model, and suitable for researching on complex network attack and defense action.

Enhanced strength and ductility in particulate-reinforced aluminum matrix composites fabricated by flake powder metallurgy

Kai, X.Z.,Li, Z.Q.,Fan, G.L.,Guo, Q.,Xiong, D.B.,Zhang, W.L.,Su, Y.S.,Lu, W.J.,Moon, W.J.,Zhang, D. Elsevier Sequoia 2013 Materials science & engineering. properties, micro Vol.587 No.-

Reinforcement agglomeration always leads to severe stress concentration and porosity, which is detrimental to the deformation ability and mechanical properties of particulate-reinforced metal matrix composites. In this study, uniform distribution of 32vol%B<SUB>4</SUB>C has been achieved in B<SUB>4</SUB>C/Al composite by means of flake powder metallurgy (Flake PM), in which flake Al powder is used as the starting material. The flake Al powder exhibits higher apparent volume than spherical powders of the same mass, and thus can provide more space to accommodate the B<SUB>4</SUB>C particles. Therefore, compared with conventional PM, Flake PM can lead to more uniform distribution of B<SUB>4</SUB>C particles in the composite powder as well as in the consolidated composite. Meanwhile, the flake Al powder has a nano skin of Al<SUB>2</SUB>O<SUB>3</SUB>, which could be fractured and dispersed inside the fine matrix grains during consolidation, and were found to induce a higher normalized strain hardening rate for the composite during deformation. As a result, the Flake PM 32vol%B<SUB>4</SUB>C/Al composite exhibits an ultimate tensile strength of 305MPa and a uniform elongation of 6.6%, 63% stronger and 13% more ductile than its counterpart fabricated by conventional PM.

Research on the Security Level of μ2 against Impossible Differential cryptanalysis

Kai Zhang,Xuejia Lai,Jie Guan,Bin Hu 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.3

In the year 2020, a new lightweight block cipher μ2 is proposed. It has both good software and hardware performance, and it is especially suitable for constrained resource environment. However, the security evaluation on μ2 against impossible differential cryptanalysis seems missing from the specification. To fill this gap, an impossible differential cryptanalysis on μ2 is proposed. In this paper, firstly, some cryptographic properties on μ2 are proposed. Then several longest 7-round impossible differential distinguishers are constructed. Finally, an impossible differential cryptanalysis on μ2 reduced to 10 rounds is proposed based on the constructed distinguishers. The time complexity for the attack is about 269.63 10-round μ2 encryptions, the data complexity is O(248), and the memory complexity is 263.57 Bytes. The reported result indicates that μ2 reduced to 10 rounds can’t resist against impossible differential cryptanalysis.

Experimental and numerical investigation on the pyrolysis of single coarse lignite particles

Kai Zhang,Changfu You,Yulei Li 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.4

This paper reports on the mathematical modeling of the pyrolysis of single coarse lignite particles using a kinetics model coupled with a heat transfer model. The parallel reaction kinetics model of the lignite pyrolysis makes no assumptions about the activation energy distribution and the conversion of sub-reactions. The pyrolysis kinetics parameters were obtained on the basis of experimental data from thermogravimetric analysis (TGA) tests. The heat transfer model includes diffusive, convective and radiative heat transfer modes. The experimental investigations were carried out for single lignite particles in an electrically heated reactor. Measurements of the temperature and mass loss were performed during the pyrolysis in a nitrogen atmosphere. The model predictions for the temperature and mass loss histories agree well with the experimental data, verifying that the mathematical model accurately evaluates the pyrolysis of lignite particles. The effects of temperature and particle size on the pyrolysis time and final residual mass fraction were evaluated using the numerical model.