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Time-varying formation tracking for uncertain second-order nonlinearmulti-agent systems

Mao-peng RAN, Li-hua XIE, Jun-cheng LI

《信息与电子工程前沿（英文）》 2019年 第20卷 第1期   页码 76-87 doi: 10.1631/FITEE.1800557

摘要：

Our study is concerned with the time-varying formation tracking problem for second-order multi-agent systems that are subject to unknown nonlinear dynamics and external disturbance, and the states of the followers form a predefined time-varying formation while tracking the state of the leader. The total uncertainty lumps the unknown nonlinear dynamics and the external disturbance, and is regarded as an extended state of the agent. To estimate the total uncertainty, we design an extended state observer (ESO). Then we propose a novel ESO based time-varying formation tracking protocol. It is proved that, under the proposed protocol, the ESO estimation error and the time-varying formation tracking error can be made arbitrarily small. An application to the target enclosing problem for multiple unmanned aerial vehicles (UAVs) verifies the effectiveness and superiority of the proposed approach.

关键词： Multi-agent system     Time-varying formation     Formation tracking     Nonlinear dynamics     Extended state observer (ESO)    

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3D finite element prediction of chip flow, burr formation, and cutting forces in micro end-milling of

A. DAVOUDINEJAD, P. PARENTI, M. ANNONI

《机械工程前沿（英文）》 2017年 第12卷 第2期   页码 203-214 doi: 10.1007/s11465-017-0421-6

摘要：

Predictive models for machining operations have been significantly improved through numerous methods in recent decades. This study proposed a 3D finite element modeling (3D FEM) approach for the micro end-milling of Al6061-T6. Finite element (FE) simulations were performed under different cutting conditions to obtain realistic numerical predictions of chip flow, burr formation, and cutting forces. FE modeling displayed notable advantages, such as capability to easily handle any type of tool geometry and any side effect on chip formation, including thermal aspect and material property changes. The proposed 3D FE model considers the effects of mill helix angle and cutting edge radius on the chip. The prediction capability of the FE model was validated by comparing numerical model and experimental test results. Burr dimension trends were correlated with force profile shapes. However, the FE predictions overestimated the real force magnitude. This overestimation indicates that the model requires further development.

关键词： 3D finite element modeling     micro end-milling     cutting force     chip formation     burr formation    

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Mechanistic insight into the biofilm formation and process performance of a passive aeration ditch (PAD

《环境科学与工程前沿（英文）》 2022年 第16卷 第7期 doi: 10.1007/s11783-021-1494-3

摘要：

• A Passive Aeration Ditch was developed to treat decentralized wastewater.

关键词： Decentralized wastewater     Passive aeration ditch     Biofilm formation     C/N ratio     Salinity     Model simulation    

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Is atmospheric oxidation capacity better in indicating tropospheric O formation?

《环境科学与工程前沿（英文）》 2022年 第16卷 第5期 doi: 10.1007/s11783-022-1544-5

摘要：

● This study summarizes and evaluates different approaches that indicate O3 formation.

关键词： O3     AOC     O3 formation regime    

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Formation mechanism and modeling of surface waviness in incremental sheet forming

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0679-1

摘要： Improving and controlling surface quality has always been a challenge for incremental sheet forming (ISF), whereas the generation mechanism of waviness surface is still unknown, which impedes the widely application of ISF in the industrial field. In this paper, the formation mechanism and the prediction of waviness are both investigated through experiments, numerical simulation, and theoretical analysis. Based on a verified finite element model, the waviness topography is predicted numerically for the first time, and its generation is attributed to the residual bending deformation through deformation history analysis. For more efficient engineering application, a theoretical model for waviness height is proposed based on the generation mechanism, using a modified strain function considering deformation modes. This work is favorable for the perfection of formation mechanism and control of surface quality in ISF.

关键词： surface waviness     incremental sheet forming     numerical simulation     formation mechanism     deformation history    

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New insights into the formation of ammonium nitrate from a physical and chemical level perspective

《环境科学与工程前沿（英文）》 2023年 第17卷 第11期 doi: 10.1007/s11783-023-1737-6

摘要：

● Factor analysis of ammonium nitrate formation based on thermodynamic theory.

关键词： Ammonium nitrate formation     Thermodynamic theory     Aerosol liquid water content     Source apportionment    

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High-precision standard enthalpy of formation for polycyclic aromatic hydrocarbons predicting from general

《化学科学与工程前沿（英文）》 2022年 第16卷 第12期   页码 1743-1750 doi: 10.1007/s11705-022-2184-9

摘要： The standard enthalpy of formation is an important predictor of the reaction heat of a chemical reaction. In this work, a high-precision method was developed to calculate accurate standard enthalpies of formation for polycyclic aromatic hydrocarbons based on the general connectivity based hierarchy (CBH) with the discrete correction of atomization energy. Through a comparison with available experimental findings and other high-precision computational results, it was found that the present method can give a good description of enthalpy of formation for polycyclic aromatic hydrocarbons. Since CBH schemes can broaden the scope of application, this method can be used to investigate the energetic properties of larger polycyclic aromatic hydrocarbons to achieve a high-precision calculation at the CCSD(T)/CBS level. In addition, the energetic properties of CBH fragments can be accurately calculated and integrated into a database for future use, which will increase computational efficiency. We hope this work can give new insights into the energetic properties of larger systems.

关键词： standard enthalpy of formation     polycyclic aromatic hydrocarbons     connectivity based hierarchy     high-precision calculation    

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The formation mechanism and the influence factor of residual stress in machining

null

《机械工程前沿（英文）》 2014年 第9卷 第3期   页码 265-269 doi: 10.1007/s11465-014-0311-0

摘要：

Residual stresses generated in cutting process have important influences on workpiece performance. The paper presents a method of theoretical analysis in order to explicate the formation mechanism of residual stresses in cutting. An important conclusion is drawn that the accumulated plastic strain is the main factor which determines the nature and the magnitude of surface residual stresses in the workpiece. On the basis of the analytical model for residual stress, a series of simulations for residual stress prediction during cutting AISI 1045 steel are implemented in order to obtain the influences of cutting speed, depth of cut and tool edge radius on surface residual stress in the workpiece. And these influences are explained from the perspective of formation mechanism of residual stress in cutting. The conclusions have good applicability and can be used to guide the parameters selection in actual production.

关键词： residual stress     analytical model     strain     plastic     cutting parameter    

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Subsurface damage pattern and formation mechanism of monocrystalline -GaO in grinding process

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0677-3

摘要： Monocrystalline beta-phase gallium oxide (β-Ga2O3) is a promising ultrawide bandgap semiconductor material. However, the deformation mechanism in ultraprecision machining has not yet been revealed. The aim of this study is to investigate the damage pattern and formation mechanism of monocrystalline β-Ga2O3 in different grinding processes. Transmission electron microscopy was used to observe the subsurface damage in rough, fine, and ultrafine grinding processes. Nanocrystals and stacking faults existed in all three processes, dislocations and twins were observed in the rough and fine grinding processes, cracks were also observed in the rough grinding process, and amorphous phase were only present in the ultrafine grinding process. The subsurface damage thickness of the samples decreased with the reduction in the grit radius and the grit depth of cut. Subsurface damage models for grinding process were established on the basis of the grinding principle, revealing the mechanism of the mechanical effect of grits on the damage pattern. The formation of nanocrystals and amorphous phase was related to the grinding conditions and material characteristics. It is important to investigate the ultraprecision grinding process of monocrystalline β-Ga2O3. The results in this work are supposed to provide guidance for the damage control of monocrystalline β-Ga2O3 grinding process.

关键词： monocrystalline beta-phase gallium oxide     grinding process     subsurface damage     nanocrystals     amorphous phase    

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Key features of new particle formation events at background sites in China and their influence on cloud

Xiaojing SHEN,Junying SUN,Xiaoye ZHANG,Yangmei ZHANG,Lu ZHANG,Ruxia FAN

《环境科学与工程前沿（英文）》 2016年 第10卷 第5期 doi: 10.1007/s11783-016-0833-2

摘要： New particle formation (NPF) event at multi rural sites in China Identifying the characteristics of NPF event Comparing NPF event between clean and polluted conditions Quantifying contribution to the cloud condensation nuclei Implication of climate and air quality Long-term continuous measurements of particle number size distributions with mobility diameter sizes ranging from 3 to 800 nm were performed to study new particle formation (NPF) events at Shangdianzi (SDZ), Mt. Tai (TS), and Lin’an (LAN) stations representing the background atmospheric conditions in the North China Plain (NCP), Central East China (CEC), and Yangtze River Delta (YRD) regions, respectively. The mean formation rate of 3-nm particles was 6.3, 3.7, and 5.8 cm ·s , and the mean particle growth rate was 3.6, 6.0, and 6.2 nm·h at SDZ, TS, and LAN, respectively. The NPF event characteristics at the three sites indicate that there may be a stronger source of low volatile vapors and higher condensational sink of pre-existing particles in the YRD region. The formation rate of NPF events at these sites, as well as the condensation sink, is approximately 10 times higher than some results reported at rural/urban sites in western countries. However, the growth rates appear to be 1–2 times higher. Approximately 12%–17% of all NPF events with nucleated particles grow to a climate-relevant size (>50 nm). These kinds of NPF events were normally observed with higher growth rate than the other NPF cases. Generally, the cloud condensation nuclei (CCN) number concentration can be enhanced by approximately a factor of 2–6 on these event days. The mean value of the enhancement factor is lowest at LAN (2–3) and highest at SDZ (~4). NPF events have also been found to have greater impact on CCN production in China at the regional scale than in the other background sites worldwide.

关键词： New particle formation     Regional background     Cloud condensation nuclei     Growth rate     Formation rate    

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Characteristics of typical dissolved black carbons and their influence on the formation of disinfection

《环境科学与工程前沿（英文）》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1585-9

摘要：

● The physicochemical and structural properties of DBC were characterized.

关键词： Dissolved black carbon (DBC)     Chlorine     Chloramine     Disinfection by-products (DBPs)     Disinfection by-products formation potential (DBPFP)    

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Strategies on designing multifunctional surfaces to prevent biofilm formation? ?

Yang Lu,Zhanguo Yue,Wei Wang,Zhiqiang Cao

《化学科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 324-335 doi: 10.1007/s11705-015-1529-z

摘要： Bacteria adhesion and biofilm formation have raised severe problems on public health, food industry and many other areas. A variety of reagents and surface coatings have been developed to kill bacteria and/or limit their interaction with surfaces. It has also attracted many efforts to integrate different bactericidal elements together and maximize antibacterial efficiency. Herein, we review mechanisms for both passive and active approaches to resist and kill bacteria respectively, and discuss integrated strategies based on these two approaches. We also offer perspective on future research direction.

关键词： antimicrobial     surface     multifunctional    

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Air pollution complex: Understanding the sources, formation processes and health effects

Min Shao,Shuxiao Wang,Armistead G. Russell

《环境科学与工程前沿（英文）》 2016年 第10卷 第5期 doi: 10.1007/s11783-016-0883-5

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NOx and H2S formation in the reductive zone of air-staged combustion of

Jinzhi CAI, Dan LI, Denggao CHEN, Zhenshan LI

《能源前沿（英文）》 2021年 第15卷 第1期   页码 4-13 doi: 10.1007/s11708-020-0804-y

摘要： Low NO combustion of blended coals is widely used in coal-fired boilers in China to control NO emission; thus, it is necessary to understand the formation mechanism of NO and H S during the combustion of blended coals. This paper focused on the investigation of reductive gases in the formation of NO and H S in the reductive zone of blended coals during combustion. Experiments with Zhundong (ZD) and Commercial (GE) coal and their blends with different mixing ratios were conducted in a drop tube furnace at 1200°C–1400°C with an excessive air ratio of 0.6–1.2. The coal conversion and formation characteristics of CO, H S, and NO in the fuel-rich zone were carefully studied under different experimental conditions for different blend ratios. Blending ZD into GE was found to increase not only the coal conversion but also the concentrations of CO and H S as NO reduction accelerated. Both the CO and H S concentrations inblended coal combustion increase with an increase in the combustion temperature and a decrease in the excessive air ratio. Based on accumulated experimental data, one interesting finding was that NO and H S from blended coal combustion were almost directly dependent on the CO concentration, and the CO concentration of the blended coal combustion depended on the single char gasification conversion.Thus, CO, NO , and H S formation characteristics from blended coal combustion can be well predicted by single char gasification kinetics.

关键词： blended coal combustion     NOx formation     H2S formation     air staged combustion    

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Structure and formation of anoxic granular sludge —A string-bag hypothesis

Binbin WANG,Dangcong PENG,Xinyan ZHANG,Xiaochang WANG

《环境科学与工程前沿（英文）》 2016年 第10卷 第2期   页码 311-318 doi: 10.1007/s11783-014-0748-8

摘要： Anoxic granular sludge was developed in a laboratory-scale sequencing batch reactor which was fed with sodium acetate and sodium nitrate as electron donor and accepter. The sludge in the reactor was almost granulated after approximately 90 days of cultivation. In the present study, a detailed examination of surface morphology and internal structure of anoxic granular sludge was conducted using scanning electron microscope. It showed that the bacteria inside the granules had a uniform, coccus-like shape. By contrast, filamentous bacteria were predominant outside the granules. These bacteria were woven and had wrapped the coccus bacteria together to form granules. The small amounts of DO in the liquid bulk promoted the growth of filamentous bacteria on the surface of the granules. A string-bag hypothesis was proposed to elucidate the structure and formation of the anoxic granular sludge. It suggested that micro-aeration could be a method to promote granulation in practical anoxic treatment systems.

关键词： granulation     sequencing batch reactor     anoxic sludge     scanning electron microscope     filamentous bacteria    

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标题 作者 时间 类型 操作

Time-varying formation tracking for uncertain second-order nonlinearmulti-agent systems

Mao-peng RAN, Li-hua XIE, Jun-cheng LI

期刊论文

3D finite element prediction of chip flow, burr formation, and cutting forces in micro end-milling of

A. DAVOUDINEJAD, P. PARENTI, M. ANNONI

期刊论文

Mechanistic insight into the biofilm formation and process performance of a passive aeration ditch (PAD

期刊论文

Is atmospheric oxidation capacity better in indicating tropospheric O formation?

期刊论文

Formation mechanism and modeling of surface waviness in incremental sheet forming

期刊论文

New insights into the formation of ammonium nitrate from a physical and chemical level perspective

期刊论文

High-precision standard enthalpy of formation for polycyclic aromatic hydrocarbons predicting from general

期刊论文

The formation mechanism and the influence factor of residual stress in machining

null

期刊论文

Subsurface damage pattern and formation mechanism of monocrystalline -GaO in grinding process

期刊论文

Key features of new particle formation events at background sites in China and their influence on cloud

Xiaojing SHEN,Junying SUN,Xiaoye ZHANG,Yangmei ZHANG,Lu ZHANG,Ruxia FAN

期刊论文

Characteristics of typical dissolved black carbons and their influence on the formation of disinfection

期刊论文

Strategies on designing multifunctional surfaces to prevent biofilm formation? ?

Yang Lu,Zhanguo Yue,Wei Wang,Zhiqiang Cao

期刊论文

Air pollution complex: Understanding the sources, formation processes and health effects

Min Shao,Shuxiao Wang,Armistead G. Russell

期刊论文

NOx and H2S formation in the reductive zone of air-staged combustion of

Jinzhi CAI, Dan LI, Denggao CHEN, Zhenshan LI

期刊论文

Structure and formation of anoxic granular sludge —A string-bag hypothesis

Binbin WANG,Dangcong PENG,Xinyan ZHANG,Xiaochang WANG

期刊论文