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Numerical analysis of role of melting rate on electroslag remelting continuous directional solidification of a die steel

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Journal of Iron and Steel Research International 2021年第12期28卷 1617-1624页

作者： jie zhang Jing Li Cheng-bin Shi State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China

The effect of melting rate on the temperature distribution,velocity field,macrosegregation and dendrite arm spacing during electroslag remelting continuous directional solidification process with a mould of 160 mm in diameter was *** mechanism of solute transport and dendrite growth of austenitic hot-work die steel during electroslag remelting process was *** results showed that a lower melting rate contributed to a higher temperature gradient as well as a shallower liquid metal molten *** the increase in the melting rate,the central counterclockwise vortex in the slag and clockwise vortex in the liquid metal molten pool grew,whereas the marginal clockwise vortex in the slag *** increasing melting rate,the macrosegregation of carbon became more serious,whereas the average value of secondary dendrite arm spacing first decreased and then *** secondary dendrite arm spacing reached a minimum value at melting rate of 98 kg/h,which indicated that 98 kg/h was a proper melting rate for electroslag remelting continuous directional solidification process with a mould of 160 mm in diameter.

关键词： Electroslag remelting continuous directional solidification Melting rate Numerical simulation Solidification structure Die steel

Real-time task processing method based on edge computing for spinning CPS

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Frontiers of Mechanical Engineering 2019年第3期14卷 320-331页

作者： Shiyong YIN Jinsong BAO jie LI jie zhang College of Mechanical Engineering Donghua University Shanghai 201620 China

Spinning production is a typical continuous manufacturing process characterized by high speed and uncertain dynamics. Each manufacturing unit in spinning production produces various real-time tasks, which may affect production efficiency and yam quality if not processed in time. This paper presents an edge computing- based method that is different from traditional centralized cloud computation because its decentralization characteristics meet the high-speed and high-response requirements of yam production. Edge computing nodes, real-time tasks, and edge computing resources are defined. A system model is established, and a real-time task processing method is proposed for the edge computing scenario. Experimental results indicate that the proposed real-time task processing method based on edge computing can effectively solve the delay problem of real-time task processing in spinning cyber-physical systems, save bandwidth, and enhance the security of task transmission.

关键词： edge computing real-time task scheduling CPS spinning

A Fully Actuated System Approach for Stabilization of Discrete-Time Multiple-Input Nonlinear Systems with Distinct Input Delays

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Journal of Systems Science & Complexity 2022年第2期35卷 670-687页

作者： WU Ai-Guo zhang jie JI Youzhou Harbin Institute of Technology(Shenzhen) Shenzhen 518055China HIT Wuhu Robot Technology Research Institute Wuhu 241008China

In this paper,the problem of stabilization is considered for discrete-time multiple-input nonlinear systems with distinct input delays law based on the fully actuated system *** order to compensate the input delays,a prediction scheme is presented to predict future states based on the closed-loop linear ***,a stabilizing law is constructed for nonlinear delayed systems by replacing the future states in the control law for the corresponding delay-free systems with their ***,numerical examples are given to verify the effectiveness of the proposed approach.

关键词： Fully actuated system approach input delays nonlinear systems prediction scheme

The journey of nisin development in China,a natural-green food preservative

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Protein & Cell 2015年第10期6卷 709-711页

作者： jie zhang Jin Zhong Institute of Microbiology Chinese Academy of Sciences

In 2005,the project“Research and Development of Nisin”led by *** Huan was awarded the National Science&Technology Progress Prize(Second Class Prize)and China National Food Industry Association(CNFIA)Science&Technology Prize(Special Prize).Nisin is a lantibiotic(bacteriocin containing unusual amino acids)(Fig.1)mainly produced by gram-positive lactic acid

关键词： natural-green development preservative

Unraveling the catalytically active phase of carbon dioxide hydrogenation to methanol on Zn/Cu alloy: Single atom versus small cluster

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Journal of Energy Chemistry 2021年第10期30卷 582-593,I0015页

作者： Xiao-Kuan Wu Hui-Min Yan Wei zhang jie zhang Guang-jie Xia Yang-Gang Wang Department of Chemistry and Guangdong Provincial Key Laboratory of Catalytic Chemistry Southern University of Science and TechnologyShenzhen 518055GuangdongChina State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing 100029China

Methanol synthesis from CO_(2)hydrogenation catalyzed by Zn/Cu alloy has been widely studied,but there is still debate on its catalytic active phase and whether the Zn can be oxidized during the reaction *** is more,as Zn atoms could locate on Zn/Cu alloy surface in forms of both single atom and cluster,how Zn surface distribution affects catalytic activity is still not *** this work,we performed a systematic theoretical study to compare the mechanistic natures and catalytic pathways between Zn single atom and small cluster on catalyst surface,where the surface oxidation was shown to play the critical *** surface oxidation,the Zn single atom/Cu is more active than the Zn small cluster/Cu,but its surface oxidation is difficult to take ***,after the easy surface oxidation by CO_(2)decomposition,the oxidized Zn small cluster/Cu becomes much more active,which even exceeds the hardlyoxidized Zn single atom/Cu to become the active *** analyses show this dramatic promotion of surface oxidation can be ascribed to the following factors:i)The O from surface oxidation could preferably occupy the strongest binding sites on the center of Zn *** makes the O intermediates bind at the Zn/Cu interface,preventing their too tight binding for further hydrogenation;ii)The higher positive charge and work function on the oxidized surface could also promote the hydrogenation of O *** work provided one more example that under certain condition,the metal cluster can be more active than the single atom in heterogeneous catalysis.

关键词： CO_(2)hydrogenation Surface oxidation Zn/Cu alloy Catalytically active phase

Actuator Fault Monitoring and Fault Tolerant Control in Distillation Columns

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International Journal of Automation and computing 2017年第1期14卷 80-92页

作者： Sulaiman Ayobami Lawal jie zhang School of Chemical Engineering and Advanced Materials Newcastle University Department of Chemical Engineering University of Lagos

This paper presents, from a practical viewpoint accommodation in distillation columns. Addressing faults in an investigation of real-time actuator fault detection, propagation and industrial processes, coupled with the growing demand for higher performance, improved safety and reliability necessitates implementation of less complex alternative control strategies in the events of malfunctions in actuators, sensors and or other system components. This work demonstrates frugality in the design and implementation of fault tolerant control system by integrating fault detection and diagnosis techniques with simple active restructurable feedback controllers and with backup feedback signals and switchable reference points to accommodate actuator fault in distillation columns based on a priori assessed control structures. A multivariate statistical process monitoring based fault detection and diagnosis technique through dynamic principal components analysis is integrated with one-point control or alternative control structure for prompt and effective fault detection, isolation and accommodation. The work also investigates effects of disturbances on fault propagation and detection. Specifically, the reflux and vapor boil-up control strategy used for a binary distillation column during normal operation is switched to one point control of the more valued product by utilizing the remaining healthy actuator. The proposed approach was implemented on two distillation processes： a simulated methanol-water separation column and the benchmark Shell standard heavy oil fractionation process to assess its effectiveness.

关键词： Dynamic principal component analysis fault detection and diagnosis distillation column fault tolerant controller inferential control.

PARAMETRIC STUDY ON THE THRUST OF BUBBLY WATER RAMJET WITH A CONVERGING-DIVERGING NOZZLE

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Journal of Hydrodynamics 2009年第5期21卷 591-599页

作者： FU Ying-jie WEI Ying-jie zhang Jia-zhong School of Astronautics Harbin Institute of Technology Harbin 150001 China

To predict the thrust of bubbly water ramjet with a converging-diverging nozzle, the physical processes occurring in the diffuser, mixing chamber and nozzle were analyzed. The mathematical models were constructed separately under the restrictions of certain assumptions. The bubbly nozzle flow was examined using a two-fluid model and accomplished by specifying the water velocity distribution in the nozzle. The numerical analysis of flow field in the nozzle shows that the Mach number at the throat is 1.009, near unity, and supersonic bubble flow appears behind the throat. There is greater thrust produced by bubbly water ramjet, compared with single-phase air ramjets. Subsequently, the influences of vessel velocity, air mass flow rate, inlet area Ai, area ratio （i.e., mixing chamber to inlet area Am/Ai）, and initial bubble radius on the thrust were emphatically investigated. Results indicate that the thrust increases with the increase of air mass flow rate, inlet area and the area ratio, and the decrease of initial bubble radius. However, the thrust weakly depends on the vessel velocity. These analytical and numerical results are useful for further investigation of bubbly water ramjet engine.

关键词： bubbly water ramjet converging-diverging nozzle bubbly flow ramjet thrust numerical simulation

Experimental Study of Heat Transfer and Film Cooling Performance of Upstream Ejected Coolant on a Turbine Endwall

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Journal of Thermal Science 2023年第2期32卷 718-728页

作者： zhang jie LIU Cunliang zhang Li YAO Chunyi LI Lin School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China

An upstream coolant injection that is different from the known leakage flow was introduced to protect the turbine *** coolant is ejected tangentially from a row of cylindrical holes situated at the side of a backward-facing *** this experiment,the effects of mass flow ratio and leakage slot width on the endwall heat transfer characteristics were *** dimensionless heat transfer coefficient(Nu)and adiabatic film cooling effectiveness(η)on an axisymmetric turbine endwall were measured by the stable-state thermochromic liquid crystal(TLC)technique and the pressure sensitive paint(PSP)technique,*** mass flow ratios(MFR)of 0.64%,0.85%,and 1.07%,as well as two leakage slot widths(W)of 3.93 mm,and 7.86 mm were *** indicate that the injection film suppresses the strength of the passage vortex,which leads to the coolant covering almost the entire *** result is more evident for the higher MFR cases,meanwhile,the corresponding averaged film cooling effectiveness is increased with the enhancement of the ***,the case with a higher MFR produces a higher heat transfer coefficient distribution,especially in the region close to the leakage slot ***,when the W is lower,the endwall presents a higherηand a lower Nu for all the cases,which can guide the optimal design of the endwall.

关键词： axisymmetric turbine endwall film cooling effectiveness heat transfer coefficient coolant injection leakage slot

Growth and decline of arboreal fungi that prey on Bursaphelenchus xylophilus and their predation rate

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Journal of Forestry Research 2022年第2期33卷 699-709页

作者： Haixiao zhang Zhiyan Wei Xuefeng Liu jie zhang Guiping Diao Heilongjiang Province Key Laboratory of Forest Protection College of ForestryNortheast Forestry UniversityHarbin 150040People’s Republic of China Key Laboratory of Saline-Alkali Vegetation Ecology Restoration Ministry of EducationCollege of Life SciencesNortheast Forestry UniversityHexing Road 26Xiangfang DistrictHarbin 150040People’s Republic of China

Pine wilt disease caused by pine wood nema-todes is a deadly disease of the genus Pinus requiring strong quarantine *** its discovery,it has been widely distributed throughout the *** is one of the coun-tries with a severe rate of infections due to its abundant pine *** this study,nematode-trapping fungi were collected from pine trees in Ninghai City,Zhejiang Prov-ince,which is the key area of pine wilt control in Febru-ary,May,September,October and *** results showed that nematode-trapping fungi of pine are abundant,especially the number and species detected in each month and are quite different;species of fungi in July,Septem-ber and November were more numerous and had higher separation *** dominant species in November was Arthrobotrys oligospora followed by Arthrobotrys cladodes;July and September it was *** each part of the tree,*** was the most widely distributed with a high separation ***,it is the dominant fungal species in the *** Bursaphelenchus xylophilus-trapping fungi are dependent on pine wood nematodes,and none were isolated from healthy pine *** arboreal ***-trapping fungi were found under the bark than in the *** is a close relationship between arboreal ***-trapping fungi and pine wood *** to make use of these resources to reduce the damage of pine wood nematode fusarium is the focus of future research.

关键词： Arboreal Bursaphelenchus xylophilus-trapping fungi Distribution Dominant species Culture conditions Rate of predation