Research on Aircraft Wake Vortex Evolution and Wake Encounter in Upper Airspace

Zhiqiang Wei,Xiaochen Li,Fei Liu 한국항공우주학회 2022 International Journal of Aeronautical and Space Sc Vol.23 No.2

With the continuous growth of air traffic flow, the hazard of aircraft encountering wake vortex at high altitude is increasing. To identify the hazard area of wake vortices and increase the capacity of upper airspace, in present work, the dissipation characteristics of the wake vortex at high altitude are analyzed. Considering the changes of flight attitude and trajectory after the aircraft enters the wake, a multi-parametric calculation method is used to study the severities of wake encounters. To determine the minimum acceptable safety level of wake encounters, the upset parameters of different aircraft-type combinations in lower airspace are calculated when the leading aircrafts are 43 typical models. Based on the multi-parametric calculation method, the safety separation of wake at high altitude is studied. Compared with those in medium and low altitudes, wake vortices in high altitudes have larger initial strengths and dissipation rates. When the leading aircraft is a super-heavy or heavy-sized aircraft, it is necessary to increase the safety separation of 1.1–2.1 km. Since the findings here are broadly applicable to assess the severity of high-altitude wake encounter, the approach provided can significantly enhance the safety of air traffic control in upper airspace.

Comparison among methods of effective energy evaluation of corn silage for beef cattle

Wei, Ming,Chen, Zhiqiang,Wei, Shengjuan,Geng, Guangduo,Yan, Peishi Asian Australasian Association of Animal Productio 2018 Animal Bioscience Vol.31 No.6

Objective: This study was conducted to compare different methods on effective energy evaluation of corn silage for beef cattle. Methods: Twenty Wandong bulls (Chinese indigenous yellow cattle) with initial body weight of $281{\pm}15.6kg$, were assigned to 1 of 5 dietary treatments with 4 animals per treatment in a randomized complete block design. Five dietary treatments included group 1 with corn silage only diet, group 2 with corn silage-concentrate basal diet (BD) and 3 groups with 3 test diets, which were the BD partly substituted by corn silage at 10%, 30%, and 60%. The total collection digestion trial was conducted for 5 d for each block after a 10-d adaptation period, and then an open-circuit respiratory cage was used to measure the gas exchange of each animal in a consecutive 4-d period. Results: The direct method-derived metabolizable energy and net energy of corn silage were 8.86 and 5.15 MJ/kg dry matter (DM), expressed as net energy requirement for maintenance and gain were 5.28 and 2.90 MJ/kg DM, respectively; the corresponding regression method-derived estimates were 8.96, 5.34, 5.37, and 2.98 MJ/kg DM, respectively. The direct method-derived estimates were not different (p>0.05) from those obtained using the regression method. Using substitution method, the nutrient apparent digestibility and effective energy values of corn silage varied with the increased corn silage substitution ratio (p<0.05). In addition, the corn silage estimates at the substitution ratio of 30% were similar to those estimated by direct and regression methods. Conclusion: In determining the energy value of corn silage using substitution method, there was a discrepancy between different substitution ratios, and the substitution ratio of 30% was more appropriate than 10% or 60% in the current study. The regression method based on multiple point substitution was more appropriate than single point substitution on energy evaluation of feedstuffs for beef cattle.

Seismic Response Analysis of Self-anchored Suspension Bridge with Multi-tower

Zhiqiang Wang,Wei Xiao,Hongyi Wei 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

Seismic performance of a self-anchored suspension bridge with three-tower were investigated. A three-dimensional nonlinear finite element model of the bridge was developed using Sap2000. Nonlinear time history analysis was conducted using Fast Nonlinear Analysis Method (FNA), while beam-column effect and nonlinear behavior of bearing and damper were taken into consideration. The analyze results showed that the middle tower was more vulnerable compared with the two side towers; there existed risk of buckling of composite beam, and the most vulnerable part lied near steel-concrete composite segment. Viscous dampers were effective to reduce seismic response of towers as well as girders.

Crystallization of BaTiO3 Thin Film at 140 $^circ$C by Metalorganic Decomposition Hydrothermal Method Using TiO2 Precursor

Zhiqiang Wei,Masanori Okuyama,Minoru Noda 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.IV

BaTiO3 thin lms with perovskite structure have been prepared on Pt/Ti/SiO2/Si substrate using a combined process of conventional MOD process and a hydrothermal treatment using TiO2 precursor. The BaTiO3 thin lms were crystallized on silicon by hydrothermal treatment at temperature of 140 C. The structure development, stoichiometry, spectroscopic, and dielectric properties of BaTiO3 thin lms have been systematically investigated. X-ray diraction patterns show that well-developed crystallites with perovskite phase have been formed. BaTiO3 thin lm obtained by the mono-treatment process shows (100) preferred orientation, but TiO2 peak still exists which indicated that the reaction is not completed. The stoichiometric BaTiO3 thin lms with a (110) preferred orientation were obtained by the multi-treatment process. AFM observation shows that the roughness of surface is improved with the multi-treatment process.The electric properties of the sample prepared by the multi-treatment process is better than that prepared by the mono-treatment process.

ML-MOEA/SOM : A Manifold-Learning-Based Multiobjective Evolutionary Algorithm Via Self-Organizing Maps

Wei Cao,Wei Zhan,ZhiQiang Chen 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.7

Under mild conditions, it can be induced from the Karush–Kuhn–Tucker condition that the Pareto set, in the decision space, of a continuous Multiobjective Optimization Problems(MOPs) is a piecewise continuous (m 1)  D manifold(where m is the number of objectives). One hand, the traditional Multiobjective Optimization Algorithms(EMOAs) cannot utilize this regularity property; on the other hand, the Regular Model-Based Multiobjective Estimation of Distribution Algorithm(RM-MEDA) only able to build the linear model of decision space using linear modelling algorithm, such as: the local principal component analysis algorithm(Local PCA).Aim at the shortcomings of EMOAs and RM-MEDA, the Manifold-Learning-Based Multiobjective Evolutionary Algorithm Via Self-Organizing Maps(ML-MOEA/SOM) is proposed for continuous multiobjective optimization problems. At each generation, first, via Self-Organizing Maps, the proposed algorithm learns such a nonlinear manifold in the decision space; then, new trial solutions is built through expanding the neurons of SOM with random noise; at the end, a nondominated sorting-based selection is used for choosing solutions for the next generation. Systematic experiments have shown that, overall, ML-MOEA/SOM outperforms NSGA-II, and is competitive with RM-MEDA in terms of convergence and diversity, on a set of test instances with variable linkages. We have demonstrated that, compared with NSGA-II and RM-MEDA, via self-Organizing maps, ML-MOEA/SOM can dig nonlinear manifold hidden in the decision space of multiobjective optimization problems.

Security Analysis of the Lightweight Cryptosystem TWINE in the Internet of Things

( Wei Li ),( Wenwen Zhang ),( Dawu Gu ),( Zhi Tao ),( Zhihong Zhou ),( Ya Liu ),( Zhiqiang Liu ) 한국인터넷정보학회 2015 KSII Transactions on Internet and Information Syst Vol.9 No.2

The TWINE is a new Generalized Feistel Structure (GFS) lightweight cryptosystem in the Internet of Things. It has 36 rounds and the key lengths support 80 bits and 128 bits, which are flexible to provide security for the RFID, smart cards and other highly-constrained devices. Due to the strong attacking ability, fast speed, simple implementation and other characteristics, the differential fault analysis has become an important method to evaluate the security of lightweight cryptosystems. On the basis of the 4-bit fault model and the differential analysis, we propose an effective differential fault attack on the TWINE cryptosystem. Mathematical analysis and simulating experiments show that the attack could recover its 80-bit and 128-bit secret keys by introducing 8 faulty ciphertexts and 18 faulty ciphertexts on average, respectively. The result in this study describes that the TWINE is vulnerable to differential fault analysis. It will be beneficial to the analysis of the same type of other iterated lightweight cryptosystems in the Internet of Things.

Security Analysis of the Khudra Lightweight Cryptosystem in the Vehicular Ad-hoc Networks

( Wei Li ),( Chenyu Ge ),( Dawu Gu ),( Linfeng Liao ),( Zhiyong Gao ),( Xiujin Shi ),( Ting Lu ),( Ya Liu ),( Zhiqiang Liu ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.7

With the enlargement of wireless technology, vehicular ad-hoc networks (VANETs) are rising as a hopeful way to realize smart cities and address a lot of vital transportation problems such as road security, convenience, and efficiency. To achieve data confidentiality, integrity and authentication applying lightweight cryptosystems is widely recognized as a rather efficient approach for the VANETs. The Khudra cipher is such a lightweight cryptosystem with a typical Generalized Feistel Network, and supports 80-bit secret key. Up to now, little research of fault analysis has been devoted to attacking Khudra. On the basis of the single nibble-oriented fault model, we propose a differential fault analysis on Khudra. The attack can recover its 80-bit secret key by introducing only 2 faults. The results in this study will provides vital references for the security evaluations of other lightweight ciphers in the VANETs.

Effects of Solution Treatment Temperatures on Microstructure and Mechanical Properties of TIG–MIG Hybrid Arc Additive Manufactured 5356 Aluminum Alloy

Wei Zuo,Le Ma,Yu Lu,Shu‑yong Li,Zhiqiang Ji,Min Ding 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6

A novel additive manufacturing method with TIG–MIG hybrid heat source was applied for fabricating 5356 aluminumalloy component. In this paper the microstructure evolution, mechanical properties and fracture morphologies of both asdepositedand heat-treated component were investigated, and how these were affected by different heat-treated temperature. The as-deposited microstructure showed dominant equiaxed grains with second phase, and the size of them is coarse in thebottom region, medium in the middle region and fine in the top region owing to different thermal cycling conditions. Comparedwith as-deposited microstructure, the size of grain becomes large and second phases gradually dissolve in the matrixas heat-treated temperature increase. Different microstructures determine the mechanical properties of component. Resultsshow that average ultimate tensile strength enhances from 226 to 270 MPa and average microhardness increases from 64.2to 75.3 HV0.1 but ductility decreases from 33 to 6.5% with heat-treated temperature increasing. For all components, thetensile properties are almost the same in the vertical direction (Z) and horizontal direction (Y) due to equiaxed grains, whichexhibits isotropy, and the mechanisms of these are analyzed in detailed. In general, the results demonstrate that hybrid archeat source has the potential to fabricate aluminum alloy component.

Comprehensive evaluation method of groundwater environment in a mining area based on fuzzy set theory

Zhiqiang Li,Binghua Zhou,Debin Teng,Wei-min Yang,Daohong Qiu 한국자원공학회 2018 Geosystem engineering Vol.21 No.2

Disordered mining activities have significantly affected the eco-geological environment of groundwater in mining area. Based on the fuzzy set theory, this paper considered three factors: the quantity of groundwater resources, groundwater environmental quality and groundwater vulnerability, and established a multi-index and multi-parameter non-linear evaluation system to make a comprehensive evaluation of the groundwater environment in the mining area. The results showed that the groundwater eco-geological environmental issues in this region were serious. The distribution area of poor quality of groundwater environment was very large, accounting for 72.5% of the studied area, and it mainly distributed in the middle and southern regions. The areas with general groundwater quality covered about 19.0% and mainly distributed in the central and northern parts in a strip shape. The areas with good groundwater quality covered about 8.5% and distributed sporadically. Moreover, in the study area, because the groundwater vulnerability was at a high level and the groundwater environmental quality was poor, the groundwater was extremely susceptible to contamination. Therefore, the groundwater environment in the area should be significantly protected during coal mining. In addition, the predicted results can provide a scientific reference for the planning and sustainable development of large coalfields.

Security Analysis of the Whirlpool Hash Function in the Cloud of Things

( Wei Li ),( Zhiyong Gao ),( Dawu Gu ),( Chenyu Ge ),( Linfeng Liao ),( Zhihong Zhou ),( Ya Liu ),( Zhiqiang Liu ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.1

With the advancement and deployment of leading-edge telecommunication technologies for sensing and collecting, computing related information, Cloud of Things (CoTs) has emerged as a typical application platform that is envisioned to revolutionize the daily activities of human society, such as intelligent transportation, modern logistics, food safety, environmental monitoring, etc. To avoid any possible malicious attack and resource abuse, employing hash functions is widely recognized as one of the most effective approaches for CoTs to achieve message integrity and data authentication. The Whirlpool hash function has served as part of the joint ISO/IEC 10118-3 International Standard by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC). In this paper, we propose an effective differential fault analysis on Whirlpool in the byte-oriented random fault model. The mathematical analysis and experimental results show that 8 random faults on average are required to obtain the current 512-bit message input of whirlpool and the secret key of HMAC-Whirlpool. Our work demonstrates that Whirlpool and HMAC-Whirlpool are both vulnerable to the single byte differential fault analysis. It provides a new reference for the security analysis of the same structure of the hash functions in the CoTs.