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纳米多孔介质中的流体流动

Weiyao Zhu,Bin Pan,Zhen Chen,Wengang Bu,Qipeng Ma,Kai Liu,Ming Yue

《工程（英文）》 2024年第32卷第1期页码 139-152 doi: 10.1016/j.eng.2023.05.014

摘要：

Fluid flow at nanoscale is closely related to many areas in nature and technology, e.g., unconventional hydrocarbon recovery, carbon dioxide geo-storage, underground hydrocarbon storage, fuel cells, ocean desalination and biomedicine. At nanoscale, interfacial forces dominate over bulk forces, and nonlinear effects are important, which significantly deviate from conventional theory. During the past decades, a series of experiments, theory and simulations have been performed to investigate fluid flow at nanoscale, which has advanced our fundamental knowledge of this topic. However, a critical review is still lacking, which has seriously limited the basic understanding of this area. Therefore herein, we systematically review experimental, theoretical and simulation works on single- and multi- phases fluid flow at nanoscale. We also clearly point out the current research gaps and future outlook. These insights will promote the significant development of nonlinear flow physics at nanoscale and will provide crucial guidance on the relevant areas.

关键词： Transport in nanoporous media Multi-phase fluid dynamics Nonlinear flow mechanisms Nonlinear flow conservation equations Interfacial forces Molecular dynamics simulation

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A brief review on nonlinear modeling methods and applications of compliant mechanisms

Guangbo HAO,Jingjun YU,Haiyang LI

《机械工程前沿（英文）》 2016年第11卷第2期页码 119-128 doi: 10.1007/s11465-016-0387-9

摘要：

Compliant mechanisms (CMs) have become one of the most popular research themes in mechanisms and robotics because of their merits. This paper aims to provide a brief systematic review on the advances of nonlinear static modeling approaches and the applications of CMs to promote interdisciplinary/multidisciplinary development for associated theories and other new applications. It also predicts likely future directions of applications and theory development.

关键词： compliant mechanisms modelling nonlinearity applications review

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A review of recent experimental investigations and theoretical analyses for pulsating heat pipes

Xin TANG, Lili SHA, Hua ZHANG, Yonglin JU

《能源前沿（英文）》 2013年第7卷第2期页码 161-173 doi: 10.1007/s11708-013-0250-1

摘要： Pulsating heat pipe (PHP), or oscillating heat pipe (OHP), a novel type of highly efficient heat transfer component, has been widely applied in many fields, such as in space-borne two-phase thermal control systems, in the cooling of electronic devices and in energy-saving technology, etc. In the present paper, the characteristics and working principles of the PHPs are introduced and the current researches in the field are described from the viewpoint of experimental tests, theoretical analyses as well as practical applications. Besides, it is found that the state-of-the-art experimental investigations on the PHPs are mainly focused on the flow visualization and the applications of nanofluids and other functional fluids, aiming at enhancing the heat transfer performance of the PHPs. In addition, it is also pointed out that the present theoretical analyses of the PHP are restricted by further development of two-phase flow theories, and are concentrated in the non-linear analyses. Numerical simulations are expected to be another research focus, in particular of the combination of the nanofluids and functional fluids.

关键词： pulsating heat pipe (PHP) flow visualization nanofluids nonlinear analysis

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FOOD SYSTEMS TRANSFORMATION: CONCEPTS, MECHANISMS AND PRACTICES

《农业科学与工程前沿（英文）》 2023年第10卷第1期页码 1-3 doi: 10.15302/J-FASE-2023491

摘要： FOOD SYSTEMS TRANSFORMATION: CONCEPTS, MECHANISMS AND PRACTICES

关键词： TRANSFORMATION SYSTEMS FOOD CONCEPTS MECHANISMS

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Gripping mechanisms in current wood harvesting machines

D. GOUBET, J. C. FAUROUX, G. GOGU

《机械工程前沿（英文）》 2013年第8卷第1期页码 42-61 doi: 10.1007/s11465-013-0358-3

摘要：

This paper focuses on the structural synthesis of gripping mechanisms used in the mechanization of the harvesting process. The importance of the gripping function in current devices like harvesting heads is underlined. This function is performed with several typical mechanisms which are listed and described in this article. This study distinguishes two kinds of planar gripping mechanisms mainly used in opening and closing the rollers: five concentric and two lateral ones. Both kinds have advantages and drawbacks. So a third kind of hybrid mechanism has been designed in order to orientate the axis of the rollers during gripping motion in order to combine concentric and lateral gripping advantages. Two planar and one spatial existing mechanisms are described. The last part of this paper presents a structural synthesis of such a spatial parallel mechanism by using the structural parameters and the general formulae established by the third author. Nine kinematic diagrams of spatial parallel mechanisms are provided.

关键词： structural synthesis parallel mechanisms gripping mechanisms wood harvesting harvesting head

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Recent development on innovation design of reconfigurable mechanisms in China

Wuxiang ZHANG, Shengnan LU, Xilun DING

《机械工程前沿（英文）》 2019年第14卷第1期页码 15-20 doi: 10.1007/s11465-018-0517-7

摘要： Reconfigurable mechanisms can deliberately reconfigure themselves by rearranging the connectivity of components to meet the different requirements of tasks. Metamorphic and origami-derived mechanisms are two kinds of typical reconfigurable mechanisms, which have attracted increasing attention in the field of mechanisms since they were proposed. Improving the independent design level, innovation, and international competitive powers of reconfigurable mechanical products is important. Summarizing related significant innovation research and application achievements periodically will shed light on research directions and promote academic exchanges. This paper presents an overview of recent developments in innovation design of reconfigurable mechanisms in China, including metamorphic and origami mechanisms and their typical applications. The future development trends are analyzed and forecasted.

关键词： innovation design reconfigurable mechanisms metamorphic mechanisms origami-derived mechanisms development trends

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CROP DIVERSITY AND SUSTAINABLE AGRICULTURE: MECHANISMS, DESIGNS AND APPLICATIONS

《农业科学与工程前沿（英文）》 2021年第8卷第3期页码 359-361 doi: 10.15302/J-FASE -2021417

摘要：

Intensive monoculture agriculture has contributed greatly to global food supply over many decades, but the excessive use of agricultural chemicals (fertilizers, herbicides and pesticides) and intensive cultivation systems has resulted in negative side effects, such as soil erosion, soil degradation, and non-point source pollution^{^[1]}. To many observers, agriculture looms as a major global threat to nature conservation and biodiversity. As noted in the Global Biodiversity Outlook 4^{^[2]}, the drivers associated with food systems and agriculture account for around 70% and 50% of the projected losses by 2050 of terrestrial and freshwater biodiversity, respectively^{^[3]}.

In addition, agricultural development and modernization of agriculture has led to a decline in the total number of plant species upon which humans depend for food^{^[4]}. Currently, fewer than 200 of some 6000 plant species grown for food contribute substantially to global food output, and only nine species account for 67% of total crop production^{^[3]}. The global crop diversity has declined in past decades.

Crop species diversity at a national scale was identified as one of the most important factors that stabilize grain production at a national level^{^[5]}. A group of long-term field experiments demonstrated that crop diversity also stabilizes temporal grain productivity at field level^{^[6]}. Therefore, maintaining crop diversity at both national and field levels is of considerable importance for food security at national and global scales.

Crop diversity includes temporal (crop rotation) and spatial diversity (e.g., intercropping, agroforestry, cultivar mixtures and cover crops) at field scale. Compared to intensive monocultures, diversified cropping systems provide additional options to support multiple ecosystem functions. For instance, crop diversity may increase above- and belowground biodiversity, improve yield stability, reduce pest and disease damage, reduce uses of chemicals, increase the efficiency of the use land, light water and nutrient resources, and enhance stress resilience in agricultural systems.

To highlight advances in research and use of crop diversity, from developing and developed countries, we have prepared this special issue on “Crop Diversity and Sustainable Agriculture” for Frontiers of Agricultural Sciences and Engineering, mainly focusing on intercropping.

Intercropping, growing at least two crops at the same time as a mixture, for example, in alternate rows or strips, is one effective pathway for increasing crop diversity at the field scale. Over recent decades, there have been substantial advances in terms of understanding of processes between intercropped species and applications in practice. There are 10 articles in this special issue including letters, opinions, review and research articles with contributions from Belgium, China, Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Switzerlands, UK, and Mexico etc.

The contributors are internationally-active scientists and agronomists contributing to intercropping research and extension. For example, Antoine Messean is coordinator of the EU H2020 Research project DiverIMPACTS “Diversification through rotation, intercropping, multiple cropping, promoted with actors and value chains towards sustainability”. Eric Justes is coordinator of the EU H2020 Research project ReMIX “Redesigning European cropping systems based on species mixtures”. Maria Finckh has worked on crop cultivar mixture and organic agriculture over many years. Henrik Hauggaard-Nielsen has outstanding expertise in intercropping research and applications, moving from detailed studies on species interactions in intercropping to working with farmers and other stakeholders to make intercropping work in practical farming. In addition to these established scientists, young scientists who have taken an interest in intercropping also contribute to the special issue, including Wen-Feng Cong, Yixiang Liu, Qi Wang, Hao Yang and others.

The first contribution to this special issue addresses how to design cropping systems to reach crop diversification, with Wen-Feng Cong and coworkers ( https://doi.org/10.15302/J-FASE-2021392) considering that it is necessary to optimize existing and/or design novel cropping systems based on farming practices and ecological principles, and to strengthen targeted ecosystem services to achieve identified objectives. In addition, the design should consider regional characteristics with the concurrent objectives of safe, nutritious food production and environmental protection.

The benefits of crop diversification have been demonstrated in many studies. Wen-Feng Cong and coworkers describe the benefits of crop diversification at three scales: field, farm, and landscape. Hao Yang and coauthors reviewed the multiple functions of intercropping. Intercropping enhances crop productivity and its stability, it promotes efficient use of resources and saves mineral fertilizer, controls pests and diseases of crops and reduces the use of pesticides. It mitigates climate change by sequestering carbon in soil, reduces non-point source pollution, and increases above- and belowground biodiversity of other taxa at field scale ( https://doi.org/10.15302/J-FASE-2021398).

Eric Justes and coworkers proposed the “4C” framework to help understand the role of species interactions in intercropping ( https://doi.org/10.15302/J-FASE-2021414). The four components are competition, complementary, cooperation (facilitation) and compensation, which work often simultaneously in intercropping. Hao Yang and coworkers used the concept of diversity effect from ecology to understand the contribution of complementarity and selection effects to enhanced productivity in intercropping. The complementarity effect consists of interspecific facilitation and niche differentiation between crop species, whereas the selection effect is mainly derived from competitive processes between species such that one species dominates the other ( https://doi.org/10.15302/J-FASE-2021398). Also, Luis Garcia-Barrios and Yanus A. Dechnik-Vazquez dissected the ecological concept of the complementarity and selection effects to develop a relative multicrop resistance index to analyze the relation between higher multicrop yield and land use efficiency and the different ecological causes of overyielding under two contrasting water stress regimes ( https://doi.org/10.15302/J-FASE-2021412).

Odette Denise Weedon and Maria Renate Finckh found that composite cross populations, with different disease susceptibilities of three winter wheat cultivars, were moderately resistant to brown rust and even to the newly emerged stripe rust races prevalent in Europe since 2011, but performance varied between standard and organic management contexts ( https://doi.org/10.15302/J-FASE-2021394).

Comparing the performance of intercrops and sole crops is critical to make a sound evaluation of the benefits of intercropping and assess interactions between species choice, intercrop design, intercrop management and factors related to the production situation and pedoclimatic context. Wopke van der Werf and coworkers review some of the metrics that could be used in the quantitative synthesis of literature data on intercropping ( https://doi.org/10.15302/J-FASE-2021413).

Interspecific interactions provide some of the advantages of intercropping, and can be divided into above- and belowground interactions. Aboveground interactions can include light and space competition, which is influenced by crop species traits. Root exudates are also important in interspecific interactions between intercropped or rotated species. Qi Wang and coworkers estimated the light interception of growth stage of maize-peanut intercropping and corresponding monocultures, and found that intercropping has higher light interception than monoculture, and increasing plant density did not further increase light interception of intercropping ( https://doi.org/10.15302/J-FASE-2021403). Yuxin Yang and coworkers reported that the root exudates of fennel (Foeniculum vulgare) can reduce infection of tobacco by Phytophthora nicotianae via inhibiting the motility and germination of the spores of the pathogen ( https://doi.org/10.15302/J-FASE-2021399).

Focusing on the application of intercropping, Wen-Feng Cong and coworkers formulated species recommendations for different regions of China for different crop diversity patterns and crop species combinations. These authors also suggested three steps for implementing crop diversification on the North China Plain. Although there are multiple benefits of crop diversification, its extension and application are hindered by various technical, organizational, and institutional barriers along value chains, especially in Europe. Based on the findings of the European Crop Diversification Cluster projects, Antoine Messéan and coworkers suggested that there needs to be more coordination and cooperation between agrifood system stakeholders, and establish multiactor networks, toward an agroecological transition of European agriculture ( https://doi.org/10.15302/J-FASE-2021406). In addition, Henrik Hauggaard-Nielsen and coworkers report the outcomes of a workshop for participatory research to overcome the barriers to enhanced coordination and networking between stakeholders ( https://doi.org/10.15302/J-FASE-2021416).

Intercropping, though highly effective in labor-intensive agriculture, may be difficult to implement in machine-intensive, large-scale modern agriculture because appropriate large equipment is not commercially available for planting and harvesting various crop mixtures grown with strip intercropping^{^[6]}. Thus, the appropriate machinery will need to be developed for further practical application in large-scale agriculture.

As the guest editors, we thank all the authors and reviewers for their great contributions to this special issue on “Crop Diversity and Sustainable Agriculture”. We also thank the FASE editorial team for their kind supports.

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New nonlinear stiffness actuator with predefined torque‒deflection profile

《机械工程前沿（英文）》 2023年第18卷第1期 doi: 10.1007/s11465-022-0721-3

摘要： A nonlinear stiffness actuator (NSA) could achieve high torque/force resolution in low stiffness range and high bandwidth in high stiffness range, both of which are beneficial for physical interaction between a robot and the environment. Currently, most of NSAs are complex and hardly used for engineering. In this paper, oriented to engineering applications, a new simple NSA was proposed, mainly including leaf springs and especially designed cams, which could perform a predefined relationship between torque and deflection. The new NSA has a compact structure, and it is lightweight, both of which are also beneficial for its practical application. An analytical methodology that maps the predefined relationship between torque and deflection to the profile of the cam was developed. The optimal parameters of the structure were given by analyzing the weight of the NSA and the mechanic characteristic of the leaf spring. Though sliding friction force is inevitable because no rollers were used in the cam-based mechanism, the sliding displacement between the cam and the leaf spring is very small, and consumption of sliding friction force is very low. Simulations of different torque‒deflection profiles were carried out to verify the accuracy and applicability of performing predefined torque‒deflection profiles. Three kinds of prototype experiments, including verification experiment of the predefined torque‒deflection profile, torque tracking experiment, and position tracking experiment under different loads, were conducted. The results prove the accuracy of performing the predefined torque‒deflection profile, the tracking performance, and the interactive performance of the new NSA.

关键词： compliant actuator nonlinear stiffness actuator nonlinear spring predefined torque−deflection profile

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Mass transport mechanisms within pervaporation membranes

Yimeng Song, Fusheng Pan, Ying Li, Kaidong Quan, Zhongyi Jiang

《化学科学与工程前沿（英文）》 2019年第13卷第3期页码 458-474 doi: 10.1007/s11705-018-1780-1

摘要： Pervaporation is an energy-efficient membrane technology for separating liquid molecules of similar physical properties, which may compete or combine with distillation separation technology in a number of applications. With the rapid development of new membrane materials, the pervaporation performance was significantly improved. Fundamental understanding of the mass transport mechanisms is crucial for the rational design of membrane materials and efficient intensification of pervaporation process. Based on the interactions between permeate molecules and membranes, this review focuses on two categories of mass transport mechanisms within pervaporation membranes: physical mechanism (solution-diffusion mechanism, molecular sieving mechanism) and chemical mechanism (facilitated transport mechanism). Furthermore, the optimal integration and evolution of different mass transport mechanisms are briefly introduced. Material selection and relevant applications are highlighted under the guidance of mass transport mechanisms. Finally, the current challenges and future perspectives are tentatively identified.

关键词： pervaporation membrane mass transport mechanisms physical mechanism chemical mechanism

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变频驱动并联水泵变压变流量运行优化调度

李洪斌,张承慧,宋军

《中国工程科学》 2001年第3卷第9期页码 52-57

摘要：

分析了变频驱动并联水泵变压变流量运行优化调度问题的常用建模方法，并比较了各种方法的优劣。常用的方法是以水泵轴功率作为目标函数，以供水指标和高效区为约束条件。另一种方法是以满足扬程指标时的实际流量与所需流量之差的二次方作为目标函数，以水泵的高效区作为约束条件。提出了一种新的建模方法，模型物理意义与实际工况严格相符，具有较高的精度，满足了工程中对水泵切换频率尽量小的要求。仿真结果表明该方法是有效的。

关键词：优化调度有约束非线性规划水泵调速

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Special issue: Mechanisms and robotics

Jingjun YU

《机械工程前沿（英文）》 2016年第11卷第2期页码 117-118 doi: 10.1007/s11465-016-0399-5

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Mean wind load induced incompatibility in nonlinear aeroelastic simulations of bridge spans

Zhitian ZHANG

《结构与土木工程前沿（英文）》 2019年第13卷第3期页码 605-617 doi: 10.1007/s11709-018-0499-x

摘要： Mean wind response induced incompatibility and nonlinearity in bridge aerodynamics is discussed, where the mean wind and aeroelastic loads are applied simultaneously in time domain. A kind of incompatibility is found during the simultaneous simulation of the mean wind and aeroelastic loads, which leads to incorrect mean wind structural responses. It is found that the mathematic expectations (or limiting characteristics) of the aeroelastic models are fundamental to this kind of incompatibility. In this paper, two aeroelastic models are presented and discussed, one of indicial-function-denoted (IF-denoted) and another of rational-function-denoted (RF-denoted). It is shown that, in cases of low wind speeds, the IF-denoted model reflects correctly the mean wind load properties, and results in correct mean structural responses; in contrast, the RF-denoted model leads to incorrect mean responses due to its nonphysical mean properties. At very high wind speeds, however, even the IF-denoted model can lead to significant deviation from the correct response due to steady aerodynamic nonlinearity. To solve the incompatibility at high wind speeds, a methodology of subtraction of pseudo-steady effects from the aeroelastic model is put forward in this work. Finally, with the method presented, aeroelastic nonlinearity resulted from the mean wind response is investigated at both moderate and high wind speeds.

关键词： bridge aerodynamics nonlinear aeroelastic model Pseudo-steady mean wind loads

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General expression for linear and nonlinear time series models

Ren HUANG, Feiyun XU, Ruwen CHEN

《机械工程前沿（英文）》 2009年第4卷第1期页码 15-24 doi: 10.1007/s11465-009-0015-z

摘要： The typical time series models such as ARMA, AR, and MA are founded on the normality and stationarity of a system and expressed by a linear difference equation; therefore, they are strictly limited to the linear system. However, some nonlinear factors are within the practical system; thus, it is difficult to fit the model for real systems with the above models. This paper proposes a general expression for linear and nonlinear auto-regressive time series models (GNAR). With the gradient optimization method and modified AIC information criteria integrated with the prediction error, the parameter estimation and order determination are achieved. The model simulation and experiments show that the GNAR model can accurately approximate to the dynamic characteristics of the most nonlinear models applied in academics and engineering. The modeling and prediction accuracy of the GNAR model is superior to the classical time series models. The proposed GNAR model is flexible and effective.

关键词： linear and nonlinear autoregressive model system identification time series analysis

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Evaluation of transmissibility for a class of nonlinear passive vibration isolators

Z. K. PENG, Z. Q. LANG, G. MENG

《机械工程前沿（英文）》 2012年第7卷第4期页码 401-409 doi: 10.1007/s11465-012-0349-9

摘要：

In this study, the concept of Output Frequency Response Functions (OFRFs) is applied to represent the transmissibility of nonlinear isolators in frequency domain. With the OFRFs estimated from numerical simulation responses, an explicit analytical relationship between the transmissibility and the nonlinear characteristic parameters is derived for a wide class of nonlinear isolators that have nonlinear anti-symmetric damping characteristics and a comprehensive pattern about how the nonlinear damping characteristic parameters might affect the force and displacement transmissibility is built for the vibration isolators. The results reveal that it is reasonable to analyze the force and displacement transmissibility of the nonlinear isolators by simply investigating the fundamental harmonic components of the force and displacement outputs of the nonlinear isolators, and the introduction of a nonlinear anti-symmetric damping into vibration isolators can significantly suppress both the force and displacement transmissibility over the resonant frequency region, but has almost no effect on the transmissibility at non-resonant regions. These conclusions are of significant importance in the analysis and design of the nonlinear vibration isolators with nonlinear anti-symmetric damping.

关键词： nonlinear vibration volterra series Output Frequency Response Functions (OFRFs) nonlinear damping vibration isolator

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Effects and mechanisms of acupuncture on women related health

《医学前沿（英文）》 doi: 10.1007/s11684-023-1051-5

摘要： Globally, public health interventions have resulted in a 30-year increase in women’s life expectancy. However, women’s health has not increased when socioeconomic status is ignored. Women’s health has become a major public health concern, for those women from developing countries are still struggling with infectious and labor-related diseases, and their counterparts in developed countries are suffering from physical and psychological disorders. In recent years, complementary and alternative medicine has attracted wide attentions with regards to maintaining women’s health. Acupuncture, a crucial component of traditional Chinese medicine, has been used to treat many obstetric and gynecological diseases for thousands of years due to its analgesic and anti-inflammatory effects and its effects on stimulating the sympathetic/parasympathetic nervous system. To fully understand the mechanism through which acupuncture exerts its effects in these diseases would significantly extend the list of available interventions and would allow for more reasonable advice to be given to general practitioners. Therefore, by searching PubMed and CNKI regarding the use of acupuncture in treating obstetric and gynecological diseases, we aimed to summarize the proven evidence of using acupuncture in maintaining women’s health by considering both its effectiveness and the underlying mechanisms behind its effects.

关键词： acupuncture women health clinical efficacy mechanism