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On asymptotic stability of the 3D Boussinesq equations without heat conduction

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Science China Mathematics 2024年第2期67卷 253-280页

作者： lihua dong Yongzhong Sun School of Physical and Mathematical Sciences Nanjing Tech UniversityNanjing 211816China Department of Mathematics Nanjing UniversityNanjing 210093China

We investigate the asymptotic stability of the solutions to Boussinesq equations without heat conduction with the initial data near a specific stationary solution in the three-dimensional domain Ω=R^(2)×(0,1).It is shown that the solution starting from a small perturbation to the stationary solution converges to it with explicit algebraic rates as time tends to infinity.

关键词： Boussinesq equations stationary solutions asymptotic stability decay rates

Predictive control for mechanical system with backlash based on hybrid model

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Journal of Systems Engineering and Electronics 2009年第6期20卷 1301-1308页

作者： Dou lihua dong Lingxun Chen Jie Xia Yuanqing Dept. of Information Science and Technology Beijing Inst. of Technology Beijing 100081 P. R. China

The mechanical system with backlash is distinguished between a＂backlash mode＂and a＂contact mode＂.The inherent switching between the two operating modes makes the system a prime example of hybrid *** eliminating the bad effect of backlash, a piecewise affine（PWA） model of the mechanical servo system with backlash is *** optimal control of constrained PWA system is obtained by taking advantage of model predictive control（MPC） method, and the explicit solution of MPC in a look-up table form is figured out by combining the dynamic programming and multi-parametric quadratic programming, thereby establishing an explicit hybrid model predictive ***, a piecewise quadratic（PWQ） function for guaranteeing the stability of closed-loop control is found by formulating the search of PWQ function as a semi-definite programming *** the tracking experiments, it is demonstrated that the explicit hybrid model predictive controller has a good traction control effect on the mechanical system with *** error meets the demands of real ***, compared to the direct on-line computation, the computation burden is reduced by the explicit solution, thereby being suitable for real-time control of system with short sampling time.

关键词： predictive controller hybrid model hybrid control backlash mode.

Corrosion Behavior of Plasma Transferred Arc Fe-based Coating Reinforced by Spherical Tungsten Carbide in Hydrochloric Acid Solutions

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Journal of Wuhan University of Technology(Materials Science) 2020年第2期35卷 299-309页

作者： dong Yaohua FAN Li CHEN Haiyan dong lihua YIN Yansheng SUN Fanghong College of Ocean Science and Engineering Shanghai Maritime UniversityShanghai 201306China College of Mechanical and Elec-tronic Engineering Shanghai Jian Qiao UniversityShanghai 201306China School of Mechanical Engineering Shanghai Jiaotong Uni-versityShanghai 200240China

Fe-based coatings reinforced by spherical tungsten carbide were deposited on 304 stainless steel using plasma transferred arc(PTA) *** composition and phase microstructure of the coatings were evaluated using scanning electron microscopy(SEM),energy dispersive spectrometer(EDS) and X-ray diffraction(XRD).The corrosion behaviors of the coatings in 0.5 mol/L HCl solution were studied using polarization curve and electrochemical impedance spectroscopy(EIS) *** experimental results shows that the tungsten carbide improves the corrosion resistance of the Fe-based alloy coating,but increase in the mass fraction of tungsten carbide leads to increasing amount of defects of holes and cracks,which results in an adverse effect on the corrosion *** defects are mainly present on the tungsten carbide but also extend to the Fe-based *** tungsten carbide,acting as a cathode,and binding material of Fe-based alloy,acting as an anode,create a galvanic corrosion *** binding material is preferentially corroded and causes the degradation of the coating.

关键词： plasma transferred arc(PTA) spherical tungsten carbide Fe-based alloys corrosion resistance electrochemical impedance spectroscopy

Wear Properties of Plasma Transferred Arc Fe-based Coatings Reinforced by Spherical WC Particles

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Journal of Wuhan University of Technology(Materials Science) 2019年第2期34卷 433-439页

作者：范丽董耀华 CHEN Haiyan dong lihua YIN Yansheng College of Mechanical and Electronic Engineering Shanghai Jian Qiao University School of Mechanical Engineering Shanghai Jiaotong University College of Ocean Science and Engineering Shanghai Maritime University

Fe-based coatings reinforced by spherical WC particles were produced on the 304 stainless steel by plasma transferred arc(PTA) to enhance the surface wear properties. Three different Fe/WC composite powder mixtures containing 0 wt%, 30 wt%, and 60 wt% of WC were investigated. The microstructure and phase composition of the Fe/WC composite PTA coatings were evaluated systemically by using scanning electron microscope(SEM) and X-ray diffraction(XRD). The wear properties of the three fabricated PTA coatings were investigated on a BRUKER UMT TriboLab. The morphologies of the worn tracks and wear debris were characterized by using SEM and 3 D non-contract profiler. The experimental results reveal that the microhardness on the cross-section and the wear resistance of the fabricated coatings increase dramatically with the increasing adding WC contents. The coating containing 60 wt% of WC possesses excellent wear resistance validated by the lower coefficients of friction(COF), narrower and shallower wear tracks and smaller wear rate. In the pure Fe-based coating, the main wear mechanism is the combination of adhesion and oxidative wear. Adhesive and two-body abrasive wear are predominated in the coating containing 30 wt% of WC, whereas threebody abrasion wear mechanism is predominated in the coating containing 60 wt% of WC.

关键词： plasma transferred arc(PTA) metal matrix composite coatings(MMCs) spherical tungsten carbide Fe-based alloys wear resistance

Mesoporous β-Co（OH）2 nanowafers and nanohexagonals obtained synchronously in one solution and their electrochemical hydrogen storage properties

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Progress in Natural Science:Materials International 2016年第6期26卷 555-561页

作者： Longqiang Wang Jingyuan Fu Yue Zhang Xiaoling Liu Yansheng Yin lihua dong Shougang Chen Institute of Materials Science and Engineering Ocean University of China College of Marine Science & Engineering Shanghai Maritime University

A water/oil two-phase solution strategy has been developed for the synthesis of various β-Co（OH）2nanostructures. More importantly, two different morphologies of β-Co（OH）2:mesoporous nanowafers and nanohexagons were successfully obtained through one reaction. Furthermore, the special mesoporous of β-Co（OH）2nanowafers and nanohexagons exhibited excellent electrochemical hydrogen storage capacities and cycling stability. The maximum capacity reached 265.9 and 215.7 mA hg-1at room temperature, *** 70 cycles, the discharging capacities of the electrode still remain above 218.2 and 175.4 mA hg-1, which indicates that the as-prepared mesoporous β-Co（OH）2nanowafers have a strong resistance against oxidation and corrosion. These results indicates that the mesoporous β-Co（OH）2nanowafers and nanohexagons may be potentially applied for electrochemical hydrogen storage.

关键词： β-Co(OH)2 Nanowafers Nanohexagonals Electrochemical hydrogen storage

Study on Immobilized Algal Cells for Treatment and Recycle of Refinery Wastewater

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China Petroleum Processing & Petrochemical Technology 2005年第3期7卷 39-42页

作者： Yu Baocheng Liu Deqi dong lihua Li Gang SINOPEC Qilu Petrochemical Company Zibo 255408 Chemical Department SooChow University

Compared to the algal oxidation pond, treatment of wastewater using the immobilized algal cell technology has excellent effect, which not only can effectively avoid the disadvantage of oxidation pond, but can also remarkably improve the efficiency of treating system and the effluent quality. When the treating system operates umder an optimal control conditions, such as a 55% loading rate, an illumination intensity of 2500-3500 lux and a hydraulic residence time of 4 hours, the COD and ammonia nitrogen removal can reach 90%. Water after deep treatment can comply with the requirement of the refinery for the quality of recycled water.

关键词： discharged wastewater immobilization of algae deep treatment reuse

Energy Conversion Law of Refuse Gasifi cation/Incineration in Low-Oxygen Plateau Areas—A Case Study of Lhasa,China

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Transactions of Tianjin University 2024年第6期30卷 498-507页

作者： Jun He Yubin Hong Hong Li Yang Yao Yongjian Xie Xinye Cheng Diyun Chen lihua dong School of Environmental Science and Engineering Tianjin UniversityTianjin 300072China Guangdong Provincial Key Laboratory of Radionuclides Pollution Control and Resources School of Environmental Science and EngineeringGuangzhou UniversityGuangzhou 510006China

Combusting refuse for energy production is promising for their treatment and disposal. However, because of geographical constraints, there has not been a stable model for the energy utilization of refuse in low-oxygen plateau areas. This paper took Lhasa as an example to conduct gasification and incineration experiments on local representative combustible refuse,and relevant energy conversion laws were investigated. Results showed that under gasification and incineration modes, the energy conversion rate of any component of refuse can reach 75% and 85% in low-oxygen plateau areas at temperatures of 450 and 650 ℃, respectively, which were 5%–10% lower than those in plain areas. The regional distribution of energy conversion of refuse in Lhasa showed that the energy conversion rate under the gasification mode was 3%–5% lower than that of the incineration mode at 450 and 650 ℃. In terms of temperature, the energy conversion rates of refuse were 5%–10% lower at 450 ℃ than those at 650 ℃, but an energy conversion rate of more than 85% can still be achieved. Thus, gasification, incineration, or gasification-assisted secondary incineration at temperatures of at least 450 ℃ is suitable for energy recovery of refuse in low-oxygen plateau areas.

关键词： Low-oxygen plateau areas Energy conversion Gasifi cation and incineration Refuse

Evaluation of clinical application of ESICM acute gastrointestinal injury grading system： a single-center observational study

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Chinese Medical Journal 2014年第10期127卷 1833-1836页

作者： Zhang dong Li Nan dong lihua Fu Yao Liu Zhongmin Wang Yushan Intensive Care Unit First Hospital Jilin University Changchun Jilin 130021 China

Background In 2012,the working group on abdominal problems of the European Society of Intensive Care Medicine （ESICM） proposed a definition and also guidelines for the grading system and treatment of acute gastrointestinal injury （AGI）.Until now,clinical reports on this topic have not been available,and the practicality of using the AGI grading system requires further validation in the ***,we conducted this study to evaluate the feasibility of utilizing the current AGI grading system in a clinical environment,and to provide evidence for its usefulness in assessing the severity and prognosis of critically ill patients with gastrointestinal *** A total of 133 patients were examined for the presence or absence of AGI,their scores on the Acute Physiology and Chronic Health Evaluation （APACHE） Ⅱ and Lausanne Intestinal Failure Estimation （LIFE） test,and 28 days *** presence and severity of AGI was based on guidelines provided by the *** patients were assigned to a NOAGI group （n=50） or an AGI group （n=83）.The AGI group was then further divided into three subgroups,consisting ofAGI Ⅰ （risk group,n=38）,AGI Ⅱ （gastrointestinal dysfunction group,n=33） and AGI Ⅲ＋AGI Ⅳ （gastrointestinal failure group,n=12）.These subgroups were then compared for differences in AGI *** There were no statistically significant differences between the AGI group and the NO-AGI group in terms of age,gender,APACHE Ⅱ score or LIFE score （P ＞ 0.05）; however,the two groups showed a significant difference in their respective rates of 28 days mortality （32.5％ in the AGI group vs.8.0％ in the NO-AGI group （P ＜ 0.05））.Patients in the three AGI subgroups showed significant differences in their 28 d mortality rates,APACHE Ⅱ,and LIFE *** grading system showed strong positive correlations with APACHE Ⅱ and LIFE scores （P ＜ 0.05）.Conclusions The currentAGI grading system can be used to identify and evaluate gastrointestinal dysfunction in criticall

关键词： acute gastrointestinal injury multiple organ dysfunction syndrome gastrointestinal dysfunction prognosis

针对Fruit v2和Fruit-80的差分错误攻击

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西安电子科技大学学报 2022年第1期49卷 121-133页

作者：乔青蓝董丽华西安电子科技大学综合业务网理论及关键技术国家重点实验室陕西西安710071

基于轻量级流密码Sprout,Fruit v2、Fruit-80、Fruit-128和Fruit-F等Fruit族小状态流密码自2016年相继被提出。Fruit族密码与Sprout结构相比,最大的区别在于Fruit族密码中非线性反馈移位寄存器与线性反馈移位寄存器的内部状态没有参与... 详细信息

基于轻量级流密码Sprout,Fruit v2、Fruit-80、Fruit-128和Fruit-F等Fruit族小状态流密码自2016年相继被提出。Fruit族密码与Sprout结构相比,最大的区别在于Fruit族密码中非线性反馈移位寄存器与线性反馈移位寄存器的内部状态没有参与轮密钥函数状态更新,这使得对Fruit族密码的密钥恢复攻击相比于Sprout更加困难。借鉴Maitra等学者对Sprout的差分错误攻击方法和Banik等学者对Grain的差分错误攻击方法,在一个相对宽松的错误模型下,对Fruit v2和Fruit-80进行了差分错误攻击。攻击中,在攻击者能够多次注入时间同步的单比特错误的假设下,首先精确识别了错误注入的位置;随后通过求解利用输出函数的一阶差分性质得到的线性方程组,完整恢复了Fruit v2与Fruit-80的整个内部状态,恢复内部状态所需的时间复杂度为216.3(线性反馈移位寄存器)和26.3(非线性反馈移位寄存器)。进一步地借助Cryptominisat-2.9.5 SAT解算器,只需要大约10 min即可求解所有密钥,整个故障攻击所需错误个数为27.3。精确识别错误位置的复杂度分别为26.3(Fruit v2)和27.3(Fruit-80)。

关键词：侧信道攻击错误攻击差分错误攻击流密码小状态流密码