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Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

《机械工程前沿（英文）》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0676-4

摘要： The control system presently used in shield posture rectification is based on driver experience, which is marginally reliable. The study of the related theory is flawed. Therefore, a decision-making approach for the deviation correction trajectory and posture rectification load for an earth pressure balance (EPB) shield is proposed. A calculation model of posture rectification load of an EPB shield is developed by considering the interactions among the cutter head, shield shell, and ground. The additional position change during the shield attitude correction is highlighted. The posture rectification loads and shield behaviors results can be solved by the proposed method. The influences of the stratum distribution (i.e., bedrock height in the upper-soft and lower-hard strata) on shield behaviors and posture rectification loads are analyzed. Results indicated that the increase of pitch angle in the upper-soft and lower-hard strata causes a sharp rise in vertical displacement. The bedrock height increases the magnitudes of the required posture rectification moments when hr/D > 0.5. For a tunnel with hr/D ≤ 0.5, the variation of hr/D has little effect on the posture rectification moments. Finally, the posture rectifying curves based on the theoretical model are compared with the target ones based on the double circular arc interpolation method. The required results can be obtained regardless of the soil–rock compound stratum distribution. The maximum rectification moment in the rock layer is almost 12.6 times that in the soil layer. Overall, this study provides a valuable reference for moment determination and the trajectory prediction of posture rectification in compound strata.

关键词： additional position change     deviation correction trajectory     earth pressure balance shield     mechanical model     posture rectification    

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Untethered quadrupedal hopping and bounding on a trampoline

Boxing WANG, Chunlin ZHOU, Ziheng DUAN, Qichao ZHU, Jun WU, Rong XIONG

《机械工程前沿（英文）》 2020年 第15卷 第2期   页码 181-192 doi: 10.1007/s11465-019-0559-5

摘要： For quadruped robots with springy legs, a successful jump usually requires both suitable elastic parts and well-designed control algorithms. However, these two problems are mutually restricted and hard to solve at the same time. In this study, we attempt to solve the problem of controller design with the help of a robot without any elastic mounted parts, in which the untethered robot is made to jump on a trampoline. The differences between jumping on hard surfaces with springy legs and jumping on springy surfaces with rigid legs are briefly discussed. An intuitive control law is proposed to balance foot contact forces; in this manner, excessive pitch oscillation during hopping or bounding can be avoided. Hopping height is controlled by tuning the time delay of the leg stretch. Together with other motion generators based on kinematic law, the robot can perform translational and rotational movements while hopping or bounding on the trampoline. Experiments are conducted to validate the effectiveness of the proposed control framework.

关键词： hopping and bounding gait     compliant mechanism     compliant contact     balance control strategy     legged locomotion control     quadruped robot    

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Push recovery for the standing under-actuated bipedal robot using the hip strategy

Chao LI,Rong XIONG,Qiu-guo ZHU,Jun WU,Ya-liang WANG,Yi-ming HUANG

《信息与电子工程前沿（英文）》 2015年 第16卷 第7期   页码 579-593 doi: 10.1631/FITEE.14a0230

摘要： This paper presents a control algorithm for push recovery, which particularly focuses on the hip strategy when an external disturbance is applied on the body of a standing under-actuated biped. By analyzing a simplified dynamic model of a bipedal robot in the stance phase, it is found that horizontal stability can be maintained with a suitably controlled torque applied at the hip. However, errors in the angle or angular velocity of body posture may appear, due to the dynamic coupling of the translational and rotational motions. To solve this problem, different hip strategies are discussed for two cases when (1) external disturbance is applied on the center of mass (CoM) and (2) external torque is acting around the CoM, and a universal hip strategy is derived for most disturbances. Moreover, three torque primitives for the hip, depending on the type of disturbance, are designed to achieve translational and rotational balance recovery simultaneously. Compared with closed-loop control, the advantage of the open-loop methods of torque primitives lies in rapid response and reasonable performance. Finally, simulation studies of the push recovery of a bipedal robot are presented to demonstrate the effectiveness of the proposed methods.

关键词： Push recovery     Balance control     Bipedal robot     Hip strategy    

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Fault tolerant control strategy for modular PWM current source inverter

《能源前沿（英文）》 2023年 第17卷 第2期   页码 228-238 doi: 10.1007/s11708-022-0852-6

摘要： In this paper, a fault-tolerant control method for an input-series output-parallel modular grid-tied pulse-width modulation (PWM) current source inverter is proposed to address the most commonly seen single symmetrical gate-commutated thyristor (SGCT) open-circuit fault problems. This method actively offsets the neutral point of the current space vector to ensure a sinusoidal output of the grid current, and it can achieve the upper limit power of the inverter under the condition of a single SGCT open-circuit fault. In addition, an active damping control method based on grid harmonic current feedback is proposed after analyzing the influence of the transformer ferromagnetic resonance caused by the neutral point offset on the power quality of the grid current. It has been demonstrated that the proposed method effectively suppresses the resonance caused by the transformer and the modified modulation, improving the grid current’s power quality.

关键词： current source converter (CSC)     fault-tolerant control     space vector modulation     active damping     resonance suppression     power quality    

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Design and evaluation of control strategies in urban drainage systems in Kunming city

Xin Dong, Senchen Huang, Siyu Zeng

《环境科学与工程前沿（英文）》 2017年 第11卷 第4期 doi: 10.1007/s11783-017-0968-9

摘要： Real time control (RTC) of urban drainage systems (UDSs) is an important measure to reduce combined sewer overflow (CSO) and urban flooding, helping achieve the aims of ‘Sponge City’. Application of RTC requires three main steps: strategy design, simulation-based evaluation and field test. But many of published RTC studies are system-specific, lacking discussions on how to design a strategy step by step. In addition, the existing studies are prone to use hydrologic model to evaluated strategies, but a more precise and dynamic insight into strategy performance is needed. To fill these knowledge gaps, based on a case UDS in Kunming city, a study on RTC strategy design and simulation-based evaluation is performed. Two off-line volume-based RTC strategy design principles, and , are emphasized. Following these principles, a detailed design procedure is shown for the case UDS resulting in three RTC strategies: static, constant and equal filling. The proposed strategies are evaluated based on a hydrodynamic model- Storm Water Management Model (SWMM) - under four typical rainfall events characterized by different return periods (1-year or 0.5 year) and different spatial distributions (uniform or uneven). The equal filling strategy outperforms other two strategies and it can achieve 10% more CSO reduction and 5% more flooding reduction relative to the no-tank case.

关键词： Urban drainage system     Real time control     Static strategy     Constant strategy     Equal filling strategy    

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Pathogen evolution, prevention/control strategy and clinical features of COVID-19: experiences from China

《医学前沿（英文）》 doi: 10.1007/s11684-023-1043-5

摘要： Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported at the end of 2019 as a worldwide health concern causing a pandemic of unusual viral pneumonia and many other organ damages, which was defined by the World Health Organization as coronavirus disease 2019 (COVID-19). The pandemic is considered a significant threat to global public health till now. In this review, we have summarized the lessons learnt during the emergence and spread of SARS-CoV-2, including its prototype and variants. The overall clinical features of variants of concern (VOC), heterogeneity in the clinical manifestations, radiology and pathology of COVID-19 patients are also discussed, along with advances in therapeutic agents.

关键词： coronavirus disease 2019     SARS-CoV-2     epidemiology     clinical features    

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FULL TIME-SPACE GOVERNANCE STRATEGY AND TECHNOLOGY FOR CROPLAND NON-POINT POLLUTION CONTROL IN CHINA

《农业科学与工程前沿（英文）》 2023年 第10卷 第4期   页码 593-606 doi: 10.15302/J-FASE-2023522

摘要：

Ensuring food safety while reducing agricultural non-point source pollution is quite challenging, especially in developing and underdeveloped countries. Effective systematic strategies and comprehensive technologies need to be developed for agricultural non-point source pollution control at the watershed scale to improve surface water quality. In this review, a proposal is made for a full time-space governance strategy that prioritizes source management followed by endpoint water pollution control. The 4R chain technology system is specifically reviewed, including source reduction, process retention, nutrient reuse and water restoration. The 4R chain technology system with the full time-space governance strategy was applied at the scale of an administrative village and proved to be a feasible solution for reducing agricultural non-point source pollution in China. In the future, a monitoring system needs to be established to trace N and P transport. Additionally, new smart fertilizer and intelligent equipment need to be developed, and relevant governance standards and supportive policies need to be set to enhance the efficacy of agricultural non-point source pollution control.

关键词： 4R chain technology system     agricultural non-point source pollution     case study     full time-space governance strategy    

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Eutrophication status and control strategy of Taihu Lake

ZHANG Limin, XIA Minfang, ZHANG Lei, WANG Chun, LU Jilai

《环境科学与工程前沿（英文）》 2008年 第2卷 第3期   页码 280-290 doi: 10.1007/s11783-008-0062-4

摘要： The water quality and eutrophication status of Taihu Lake in recent years are presented and the pollution trends are analyzed. It is shown that because of unreasonable industrial structures, pollution discharge per GDP is high within the Taihu basin, and the pollution discharge from point and non-point sources exceed the basin’s environmental carrying capacity. Especially, excessive pollutants containing nitrogen and phosphorus are being discharged. Moreover, eutrophication may also result from internal pollution sources such as the release of nutrient elements from sediment. All these factors have resulted in the water quality deterioration of Taihu Lake. To solve this environmental problem, possible control strategies are summarized, including the control of internal pollution sources and inflow-river pollution, ecological restoration and reconstruction of the degraded lakeside zone ecosystem, clean water diversion, dredging, and manual algae removal.

关键词： eutrophication     GDP     capacity     reconstruction     ecological restoration    

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Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

《化学科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 162-172 doi: 10.1007/s11705-009-0267-5

摘要： Bubble columns are widely used in chemical and biochemical processes due to their excellent mass and heat transfer characteristics and simple construction. However, their fundamental hydrodynamic behaviors, which are essential for reactor scale-up and design, are still not fully understood. To develop design tools for engineering purposes, much research has been carried out in the area of computational fluid dynamics (CFD) modeling and simulation of gas-liquid flows. Due to the importance of the bubble behavior, the bubble size distribution must be considered in the CFD models. The population balance model (PBM) is an effective approach to predict the bubble size distribution, and great efforts have been made in recent years to couple the PBM into CFD simulations. This article gives a selective review of the modeling and simulation of bubble column reactors using CFD coupled with PBM. Bubble breakup and coalescence models due to different mechanisms are discussed. It is shown that the CFD-PBM coupled model with proper bubble breakup and coalescence models and interphase force formulations has the ability of predicting the complex hydrodynamics in different flow regimes and, thus, provides a unified description of both the homogeneous and heterogeneous regimes. Further study is needed to improve the models of bubble coalescence and breakup, turbulence modification in high gas holdup, and interphase forces of bubble swarms.

关键词： bubble column     computational fluid dynamics     bubble breakup and coalescence     population balance model     bubble size distribution    

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Gut microbial balance and liver transplantation: alteration, management, and prediction

null

《医学前沿（英文）》 2018年 第12卷 第2期   页码 123-129 doi: 10.1007/s11684-017-0563-2

摘要：

Liver transplantation is a conventional treatment for terminal stage liver diseases. However, several complications still hinder the survival rate. Intestinal barrier destruction is widely observed among patients receiving liver transplant and suffering from ischemia–reperfusion or rejection injuries because of the relationship between the intestine and the liver, both in anatomy and function. Importantly, the resulting alteration of gut microbiota aggravates graft dysfunctions during the process. This article reviews the research progress for gut microbial alterations and liver transplantation. Especially, this work also evaluates research on the management of gut microbial alteration and the prediction of possible injuries utilizing microbial alteration during liver transplantation. In addition, we propose possible directions for research on gut microbial alteration during liver transplantation and offer a hypothesis on the utilization of microbial alteration in liver transplantation. The aim is not only to predict perioperative injuries but also to function as a method of treatment or even inhibit the rejection of liver transplantation.

关键词： gut microbial balance     liver transplantation     ischemia–reperfusion     acute rejection    

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Nonlinear sealing force of a seawater balance valve used in an 11000-meter manned submersible

《机械工程前沿（英文）》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0726-y

摘要： Balance valve is a core component of the 11000-meter manned submersible “struggle,” and its sealing performance is crucial and challenging when the maximum pressure difference is 118 MPa. The increasing sealing force improves the sealing performance and increases the system’s energy consumption at the same time. A hybrid analytical–numerical–experimental (ANE) model is proposed to obtain the minimum sealing force, ensuring no leakage at the valve port and reducing energy consumption as much as possible. The effects of roundness error, environmental pressure, and materials on the minimum sealing force are considered in the ANE model. The basic form of minimum sealing force equations is established, and the remaining unknown coefficients of the equations are obtained by the finite element method (FEM). The accuracy of the equation is evaluated by comparing the independent FEM data to the equation data. Results of the comparison show good agreement, and the difference between the independent FEM data and equation data is within 3% when the environmental pressure is 0–118 MPa. Finally, the minimum sealing force equation is applied in a balance valve to be experimented using a deep-sea simulation device. The balance valve designed through the minimum sealing force equation is leak-free in the experiment. Thus, the minimum sealing force equation is suitable for the ultrahigh pressure balance valve and has guiding significance for evaluating the sealing performance of ultrahigh pressure balance valves.

关键词： seawater balance valve     sealing performance     hybrid ANE model     FEM     minimum sealing force equation    

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Quantitative analysis of yield and soil water balance for summer maize on the piedmont of the North China

Jingjing WANG,Feng HUANG,Baoguo LI

《农业科学与工程前沿（英文）》 2015年 第2卷 第4期   页码 295-310 doi: 10.15302/J-FASE-2015074

摘要： The North China Plain (NCP) is a major grain production area in China, but the current winter wheat-summer maize system has resulted in a large water deficit. This water-shortage necessitates the improvement of crop water productivity in the NCP. A crop water model, AquaCrop, was adopted to investigate yield and water productivity (WP) for rain-fed summer maize on the piedmont of the NCP. The data sets to calibrate and validate the model were obtained from a 3-year (2011–2013) field experiment conducted on the Yanshan piedmont of the NCP. The range of root mean square error (RMSE) between the simulated and measured biomass was 0.67–1.25 t·hm , and that of relative error (RE) was 9.4%–15.4%, the coefficient of determination ( ) ranged from 0.992 to 0.994. The RMSE between the simulated and measured soil water storage at depth of 0–100 cm ranged from 4.09 to 4.39 mm; and RE and in the range of 1.07%–1.20% and 0.880–0.997, respectively. The WP as measured by crop yield per unit evapotranspiration was 2.50–2.66 kg·m . The simulated impact of long-term climate (i.e., 1980–2010) and groundwater depth on crop yield and WP revealed that the higher yield and WP could be obtained in dry years in areas with capillary recharge from groundwater, and much lower values elsewhere. The simulation also suggested that supplementary irrigation in areas without capillary groundwater would not result in groundwater over-tapping since the precipitation can meet the water required by both maize and ecosystem, thus a beneficial outcome for both food and ecosystem security can be assured.

关键词： AquaCrop     summer maize     soil water balance     water productivity    

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Mass and heat balance calculations and economic evaluation of an innovative biomass pyrolysis project

Quanyuan WEI, Yongshui QU, Tianwei TAN

《化学科学与工程前沿（英文）》 2011年 第5卷 第3期   页码 355-361 doi: 10.1007/s11705-010-0567-9

摘要： Biomass can be converted into flammable gas, charcoal, wood vinegar, wood tar oil and noncombustible materials with thermo-chemical pyrolysis reactions. Many factors influence these processes, such as the properties of the raw materials, and temperature control and these will affect the products that are produced. Based on the data from a straw pyrolysis demonstration project, the mass and heat balance of the biomass pyrolysis process were analyzed. The statistical product and service solutions (SPSS) statistical method was used to analyze the data which were monitored on-site. A cost-benefit analysis was then used to study the viability of commercializing the project. The analysis included net present value, internal rate of return and investment payback period. These results showed that the straw pyrolysis project has little risk, and will produce remarkable economic benefits.

关键词： mass balance     heat balance     biomass pyrolysis     economic benefit    

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Regenerative braking control strategy in mild hybrid electric vehicles equipped with automatic manual

QIN Datong, YE Ming, LIU Zhenjun

《机械工程前沿（英文）》 2007年 第2卷 第3期   页码 364-369 doi: 10.1007/s11465-007-0064-0

摘要： The actual regenerative braking force of an integrated starter/generator (ISG), which is varied with desired braking deceleration and vehicle speed, is calculated based on an analysis of the required deceleration, maximum braking force of ISG, engine braking force and state of charge (SOC) of battery. Braking force distribution strategies are presented according to the actual regenerative braking force of ISG. To recover the vehicle s kinetic energy maximally, braking shift rules for a mild hybrid electric vehicle (HEV) equipped with automatic manual transmission (AMT) are brought forward and effects of transmission ratios are considered. A test-bed is built up and regenerative braking tests are carried out. The results show that power recovered by the braking shift rules is more than that recovered by the normal braking control rules.

关键词： SOC     Braking     battery     regenerative braking     starter/generator    

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Analysis of load transfer stability control strategy in hydraulic synchronized continuous slippage

LIU Yan-bo, WU Jian-zhong, ZHANG Xuan

《机械工程前沿（英文）》 2006年 第1卷 第2期   页码 222-226 doi: 10.1007/s11465-006-0007-1

摘要： Hydraulic synchronized continuous slippage technique, which integrates mechanical, electrical and hydraulic control, is introduced in this paper for the practical requirements of some construction projects. The core of this technique (the stability of the load transfer) is illustrated in detail. Three speed control strategies to transfer the load excessive, lower and same speed are presented to accomplish the smoothness and stability in the process of slippage. An optimization of the speed control strategy (same speed) is deduced from the modeling analysis and its validity and maneuverability are tested by practical application, which provides evidence for similar engineering in theory and practice.

关键词： excessive     slippage technique     optimization     continuous slippage     engineering    

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标题 作者 时间 类型 操作

Deviation correction strategy for the earth pressure balance shield based on shield–soil interactions

期刊论文

Untethered quadrupedal hopping and bounding on a trampoline

Boxing WANG, Chunlin ZHOU, Ziheng DUAN, Qichao ZHU, Jun WU, Rong XIONG

期刊论文

Push recovery for the standing under-actuated bipedal robot using the hip strategy

Chao LI,Rong XIONG,Qiu-guo ZHU,Jun WU,Ya-liang WANG,Yi-ming HUANG

期刊论文

Fault tolerant control strategy for modular PWM current source inverter

期刊论文

Design and evaluation of control strategies in urban drainage systems in Kunming city

Xin Dong, Senchen Huang, Siyu Zeng

期刊论文

Pathogen evolution, prevention/control strategy and clinical features of COVID-19: experiences from China

期刊论文

FULL TIME-SPACE GOVERNANCE STRATEGY AND TECHNOLOGY FOR CROPLAND NON-POINT POLLUTION CONTROL IN CHINA

期刊论文

Eutrophication status and control strategy of Taihu Lake

ZHANG Limin, XIA Minfang, ZHANG Lei, WANG Chun, LU Jilai

期刊论文

Simulation of bubble column reactors using CFD coupled with a population balance model

Tiefeng WANG

期刊论文

Gut microbial balance and liver transplantation: alteration, management, and prediction

null

期刊论文

Nonlinear sealing force of a seawater balance valve used in an 11000-meter manned submersible

期刊论文

Quantitative analysis of yield and soil water balance for summer maize on the piedmont of the North China

Jingjing WANG,Feng HUANG,Baoguo LI

期刊论文

Mass and heat balance calculations and economic evaluation of an innovative biomass pyrolysis project

Quanyuan WEI, Yongshui QU, Tianwei TAN

期刊论文

Regenerative braking control strategy in mild hybrid electric vehicles equipped with automatic manual

QIN Datong, YE Ming, LIU Zhenjun

期刊论文

Analysis of load transfer stability control strategy in hydraulic synchronized continuous slippage

LIU Yan-bo, WU Jian-zhong, ZHANG Xuan

期刊论文