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Numerical analysis of strongly nonlinear oscillation systems using He’s max-min method

H. BABAZADEH, G. DOMAIRRY, A. BARARI, R. AZAMI, A. G. DAVODI

《机械工程前沿（英文）》 2011年 第6卷 第4期   页码 435-441 doi: 10.1007/s11465-011-0243-x

摘要：

Nonlinear functions are crucial points and terms in engineering problems. Actual and physical problems can be solved by solving and processing such functions. Thus, most scientists and engineers focus on solving these equations. This paper presents a novel method called the max-min method for presenting an accurate approximate analytical solution to strong nonlinear oscillators. It can solve many linear or nonlinear differential equations without the tangible restriction of sensitivity to the degree of the nonlinear term. It is also quite convenient due to the reduction in the size of calculations. The algorithm suggests a promising approach and is systematically illustrated step by step.

关键词： min-max method     nonlinear oscillation     duffing equation     mathematical pendulum     He’s energy balance method    

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Self-organizing method for collaboration in multi-robot system on basis of balance principle

DONG Yangbin, JIANG Jinping, HE Yan

《机械工程前沿（英文）》 2008年 第3卷 第3期   页码 283-287 doi: 10.1007/s11465-008-0044-z

摘要： By analyzing the operation characteristics of two subtasks that have resource dependency on each other, this paper demonstrates the impact of progress relation between the two subtasks on the whole task’s progress, and then puts forward a self-organizing principle called balance principle that keeps the individual profit between robots equal. Furthermore, an algorithm is designed for adjusting subtask selection on the basis of this principle. Simulation shows the validity of the algorithm on self-organizing task allocation in a multi-robot system.

关键词： algorithm     self-organizing principle     validity     Simulation     allocation    

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Situation and measures of China’s CO

Jiankun HE

《能源前沿（英文）》 2018年 第12卷 第3期   页码 353-361 doi: 10.1007/s11708-018-0564-0

摘要：

Global response to climate change has entered the phase of full implementation of the Paris Agreement. To control the global temperature rise below 2°C, all countries must make more efforts to reduce emission. China has combined its goal of emission reduction for combating climate change with its domestic sustainable development strategy to promote energy revolution and the transition of economic development to low-carbon patterns. Through reinforcing the commitment and action before 2020, the CO2 intensity of GDP can decrease by more than 50% by 2020 compared with that of 2005, and the external commitment target of a 40%–45% decrease can be over fulfilled. Currently, under the new economic normal, China further strengthens the policy measure, vigorously saves energy, enhances energy use efficiency and the economic output benefit, and simultaneously develops new and renewable energy and accelerates energy structural decarbonization, so that the annual decrease rate of the CO2 intensity of GDP keeps a high level of more than 4% and remains increasing. Thus, the decrease rate of the CO2 intensity of GDP will exceed the GDP growth rate, and then CO2 emission will peak around 2030. This will promote the fundamental turning of economic development mode, and lay a foundation for the establishment of a sustainable energy system with near-zero emissions and with new and renewable energy as the main body in the second half of this century. China implements the concept of green low-carbon development and accelerates the low carbon transition of energy and economy to achieve win-win results in economic growth and CO2 emission mitigation, and these policies and actions will also provide experiences for many other developing countries. On the other hand, China will continue to play a positive and constructive leading role in the implementation of the Paris Agreement internationally, and promote the construction of new mechanisms of win-win cooperation, fairness and justice and common development for global climate governance. Moreover, China will make an effort to build a community of common destiny for mankind, promote pragmatic cooperation among countries, especially among developing countries, and take combating climate change as a new development opportunity for jointly moving toward climate-friendly low-carbon economic development path.

关键词： climate change     the Paris Agreement     energy revolution     NDC (national determined contribution) goals    

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Time reversal method for guided wave inspection in pipes

DENG Fei, WU Bin, HE Cunfu

《机械工程前沿（英文）》 2008年 第3卷 第3期   页码 251-260 doi: 10.1007/s11465-008-0050-1

摘要： The application of the time reversal method in pipe-like structures based on finite element method (FEM) is investigated. A steel pipe model measuring 70 mm × 3.5 mm is used to analyze the reflection coefficient of the (0,2) mode with the time reversal process. Simulation results show that the time reversal array method is beneficial to the improvement of the signal-to-noise ratio of a guided wave inspection system. As the intercepting window is widened, more energy is included in re-emitted signals, which leads to a large reflection coefficient of the (0,2) mode. In parallel, a circumferential locating method based on the time reversal method is described. The time reversal process used for guided wave inspection leads to the temporal and spatial focusing. When the time reversal signals are re-emitted, the angular profile obtained at the axial location of the defect can be used to determine the circumferential location of the defect. Except for a pipe with one defect, the circumferential locating method has been verified on another pipe model with two defects. Meanwhile, the elements number of the time reversal array has been discussed for enhancing the discrimination of the defect circumferential location.

关键词： reversal process     beneficial     circumferential location     energy     number    

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中国风能发展战略研究

贺德馨

《中国工程科学》 2011年 第13卷 第6期   页码 95-100

摘要：

2008年2月中国工程院启动中国能源中长期（2030、2050）发展战略研究重大咨询项目，项目设置6个课题，根据可再生能源课题的安排，风能组的工作是在“中国可再生能源发展战略研究”的基础上，进一步摸清风能资源家底，从战略的角度对风能市场、产业、技术和应用进行综合分析，提出我国风能中长期发展的战略目标、技术路线、发展重点和政策措施。文章简要介绍了研究的结果。

关键词： 可再生能源     风能     可持续发展     战略研究    

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Leptin signaling and leptin resistance

null

《医学前沿（英文）》 2013年 第7卷 第2期   页码 207-222 doi: 10.1007/s11684-013-0263-5

摘要：

Leptin is secreted into the bloodstream by adipocytes and is required for the maintenance of energy homeostasis and body weight. Leptin deficiency or genetic defects in the components of the leptin signaling pathways cause obesity. Leptin controls energy balance and body weight mainly through leptin receptor b (LEPRb)-expressing neurons in the brain, particularly in the hypothalamus. These LEPRb-expressing neurons function as the first-order neurons that project to the second-order neurons located within and outside the hypothalamus, forming a neural network that controls the energy homeostasis and body weight. Multiple factors, including inflammation and endoplasmic reticulum (ER) stress, contribute to leptin resistance. Leptin resistance is the key risk factor for obesity. This review is focused on recent advance about leptin action, leptin signaling, and leptin resistance.

关键词： leptin signaling     leptin receptor     energy balance     leptin resistance     obesity    

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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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Using balance of seasonal herbage supply and demand to inform sustainable grassland management on the

Xinquan ZHAO, Liang ZHAO, Qi LI, Huai CHEN, Huakun ZHOU, Shixiao XU, Quanmin DONG, Gaolin WU, Yixin HE

《农业科学与工程前沿（英文）》 2018年 第5卷 第1期   页码 1-8 doi: 10.15302/J-FASE-2018203

摘要： To mitigate the impacts of grassland degradation on the Qinghai–Tibetan Plateau (QTP), in recent decades China has been implementing large-scale conservation programs and has invested about 42 billion CNY (7 billion USD). However, these programs are faced with major challenges involving trade-offs between ecological function, livestock production and income of pastoralists. Scientific assessments, as well as technical and policy issues, have not fully captured the complex ecological, social and economic dynamics of the challenges facing grassland management on the QTP. Pastoral livestock production on the QTP is characterized by imbalance in both quality and quantity between livestock seasonal nutrient requirements and herbage production, which forces pastoralists to keep larger numbers of livestock for longer periods, leading to overgrazing. To solve these problems, an integrated crop-livestock system is promoted to improve the efficiency of livestock production and conserve natural grassland as well for a sustainable system for the QTP.

关键词： ecosystem function     grassland degradation     grassland management     integrated rangeland-cropland-livestock production system     Qinghai–Tibetan Plateau    

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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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ORGANIC CARBON STOCKS IN A SILTY TEXTURED SOIL FOLLOWING REINTEGRATION OF A 20 YEARS OLD × SITE INTO A CROP ROTATION

《农业科学与工程前沿（英文）》 2023年 第10卷 第2期   页码 183-197 doi: 10.15302/J-FASE-2023485

摘要：

● 0.98 Mg·ha−1·yr−1 Corg accumulation under miscanthus over 26 years.

关键词： biobased energy crops     C balance     humus accumulation    

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China’s energy—challenges and strategies

NI Weidou

《能源前沿（英文）》 2007年 第1卷 第1期   页码 1-8 doi: 10.1007/s11708-007-0001-2

摘要： In this century, China started facing five major challenges in the energy field: energy supply, shortage of liquid fuel, environmental pollution, green house gas (GHG) emission, and energy supply in rural areas. In this paper, the Chinese energy development strategy and general technical scheme (including energy conservation, utilization of coal, alternative fuel and renewable energy) are discussed, and some key scientific problems in the fundamental research of energy are put forward.

关键词： scientific     development strategy     utilization     technical     environmental pollution    

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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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China’s hydropower energy system toward carbon neutrality

《工程管理前沿（英文）》   页码 677-682 doi: 10.1007/s42524-022-0196-2

摘要： Wind and solar powers will gradually become dominant energies toward carbon neutrality. Large-scale renewable energies, with strong stochasticity, high volatility, and unadjustable features, have great impacts on the safe operation of power system. Thus, an advanced hydropower energy system serving multiple energies is required to respond to volatility, with expanding role from a “stable energy supplier” to a “flexible efficiency regulator”. Future research and application can be considered from three aspects: 1) system expansion (e.g., the construction of large-scale hydropower/renewable energy bases in China, the construction of transnational hydropower energy internet, and the functional transformation of traditional hydropower reservoirs and generating units); 2) efficiency promotion (e.g., advanced intelligent forecasting, multi-objective operation, and risk management methods); and 3) supporting measures (e.g., market reform, benefit compensation and policy mechanism, technical standards, and laws and regulations).

关键词： hydropower system     carbon neutrality     artificial intelligence    

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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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标题 作者 时间 类型 操作

Numerical analysis of strongly nonlinear oscillation systems using He’s max-min method

H. BABAZADEH, G. DOMAIRRY, A. BARARI, R. AZAMI, A. G. DAVODI

期刊论文

Self-organizing method for collaboration in multi-robot system on basis of balance principle

DONG Yangbin, JIANG Jinping, HE Yan

期刊论文

Situation and measures of China’s CO

Jiankun HE

期刊论文

Time reversal method for guided wave inspection in pipes

DENG Fei, WU Bin, HE Cunfu

期刊论文

中国风能发展战略研究

贺德馨

期刊论文

Leptin signaling and leptin resistance

null

期刊论文

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

Tiefeng WANG

期刊论文

Using balance of seasonal herbage supply and demand to inform sustainable grassland management on the

Xinquan ZHAO, Liang ZHAO, Qi LI, Huai CHEN, Huakun ZHOU, Shixiao XU, Quanmin DONG, Gaolin WU, Yixin HE

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

ORGANIC CARBON STOCKS IN A SILTY TEXTURED SOIL FOLLOWING REINTEGRATION OF A 20 YEARS OLD × SITE INTO A CROP ROTATION

期刊论文

China’s energy—challenges and strategies

NI Weidou

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

China’s hydropower energy system toward carbon neutrality

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