Geothermal is a clean energy source that is freely available in the subsurface. The exploitation of this vital resource needs intensive exploration in order to identify and quantify its occurrence. The three parameter...Geothermal is a clean energy source that is freely available in the subsurface. The exploitation of this vital resource needs intensive exploration in order to identify and quantify its occurrence. The three parameters considered when assessing the viability of a geothermal system include;heat source, fractures and fluids. Geological structures are important in transportation of fluids to and from the heat source aiding in recharge of the geothermal system and enhancing productivity. Remote sensing method was applied in mapping the structures at Barrier Volcanic Complex (BVC) by using hill shading technique which utilized four illumination angles of the sun (azimuth) i.e. 45°, 90°, 150°, and 315°, constant elevation of 45° and exaggeration of 10. The data used was Shuttle Radar Topographic Mission (SRTM) Satellite Imagery. ArcGIS Software was used for lineaments delineation and density mapping, PCI Geomatica was used to generate major faults, while Georose and Rockworks 17 were used to generate the rose diagrams. Geological structural analysis was done by delineating lineaments, determining the density distribution of lineaments and finally determining the structural trends of lineaments. The generated major faults in the area and the location of the occurrence of surface manifestations were compared with the generated lineaments. A total of 260 lineaments were generated whereby at 45° there was a total of 60 lineaments, at 90° 95 lineaments, at 150° 61 lineaments, and at 315° 44 lineaments. The results of structural analysis in the area as shown by the rose diagrams indicate an NNE-SSW and N-S trending of structures. In conclusion, the study area is highly fractured as indicated by the presence of numerous lineaments. These lineaments provide good recharge to the geothermal system and enhance the geothermal reservoir in the area.展开更多
In addition to the tens of millions of medical doses consumed annually around the world,a vast number of nuclear magnetic resonance imaging(MRI)contrast agents are being deployed in MRI research and development,offeri...In addition to the tens of millions of medical doses consumed annually around the world,a vast number of nuclear magnetic resonance imaging(MRI)contrast agents are being deployed in MRI research and development,offering precise diagnostic information,targeting capabilities,and analyte sensing.Superparamagnetic iron oxide nanoparticles(SPIONs)are notable among these agents,providing effective and versatile MRI applications while also being heavy-metal-free,bioconjugatable,and theranostic.We designed and implemented a novel two-pronged computational and experimental strategy to meet the demand for the efficient and rigorous development of SPION-based MRI agents.Our MATLAB-based modeling simulation and magnetic characterization revealed that extremely small maghemite SPIONs in the 1-3 nm range possess significantly reduced transversal relaxation rates(R_(2))and are therefore preferred for positive(T_(1)-weighted)MRI.Moreover,X-ray diffraction and X-ray absorption fine structure analyses demonstrated that the diffraction pattern and radial distribution function of our SPIONs matched those of the targeted maghemite crystals.In addition,simulations of the X-ray near-edge structure spectra indicated that our synthesized SPIONs,even at 1 nm,maintained a spherical structure.Furthermore,in vitro and in vivo MRI investigations showed that our 1-nm SPIONs effectively highlighted whole-body blood vessels and major organs in mice and could be cleared through the kidney route to minimize potential post-imaging side effects.Overall,our innovative approach enabled a swift discovery of the desired SPION structure,followed by targeted synthesis,synchrotron radiation spectroscopic studies,and MRI evaluations.The efficient and rigorous development of our high-performance SPIONs can set the stage for a computational and experimental platform for the development of future MRI agents.展开更多
This paper addresses the problem of the input design of large-scale complex networks.Two types of network components,redundant inaccessible strongly connected component(RISCC)and intermittent inaccessible strongly con...This paper addresses the problem of the input design of large-scale complex networks.Two types of network components,redundant inaccessible strongly connected component(RISCC)and intermittent inaccessible strongly connected component(IISCC)are defined,and a subnetwork called a driver network is developed.Based on these,an efficient method is proposed to find the minimum number of controlled nodes to achieve structural complete controllability of a network,in the case that each input can act on multiple state nodes.The range of the number of input nodes to achieve minimal control,and the configuration method(the connection between the input nodes and the controlled nodes)are presented.All possible input solutions can be obtained by this method.Moreover,we give an example and some experiments on real-world networks to illustrate the effectiveness of the method.展开更多
This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization. We first give an overview of natural phenomena of structurally-controlled ore formation and...This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization. We first give an overview of natural phenomena of structurally-controlled ore formation and the background theory and mechanisms for such controls. We then provide the results of a group of simple 2D numerical models validated through comparison with Cu-vein structure observed near the Shilu Copper deposit （Yangchun, Guangdong Province, China） and finally a case study of 3D numerical modelling applied to the Hodgkinson Province in North Queensland （Australia）. Two modelling approaches, discrete deformation modelling and continuum coupled deformation and fluid flow modelling, are involved. The 2D model-derived patterns are remarkably consistent with the Cu-vein structure from the Shilu Copper deposit, and show that both modelling approaches can realistically simulate the mechanical behaviours of shear and dilatant fractures. The continuum coupled deformation and fluid flow model indicates that pattern of the Cu- veins near the Shilu deposit is the result of shear strain localization, development of dilation and fluid focussing into the dilatant fracture segments. The 3D case-study models （with deformation and fluid flow coupling） on the Hodgkinson Province generated a number of potential gold mineralization展开更多
This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping.An off-and-towards-equilibrium (OTE) algorithm is employed to examine th...This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping.An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD system by considering the damping as an assumptive control action.The damping modification of the SATMD is carried out according to the proposed OTE algorithm,which is formulated based on analysis of the structural movement under external excitations,and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey and a ten-storey shear structures with a SATMD on the roof are conducted.The effectiveness on vibration reduction of MDOF systems subjected to seismic excitations is discussed.Analysis results show that the behavior of the structure with a SATMD is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also verified.展开更多
The recent developments of theoretical research, model tests and engineering applications of structural control in China's Mainland are reviewed in this paper. It includes seismic isolation, passive energy dissipa...The recent developments of theoretical research, model tests and engineering applications of structural control in China's Mainland are reviewed in this paper. It includes seismic isolation, passive energy dissipation, active and semi-active control, smart materials and smart structural systems. It can be seen that passive control methods, such as seismic isolation and energy dissipation methods, have developed into the mature stage in China. At the same time, great progress has been made in active and semi-active control, and smart actuators or smart dampers and smart structural systems. Finally, some future research initiatives for structural control in civil engineering are suggested. Keywords state-of-the-art review - structural control - seismic isolation - passive energy dissipation - active and semi-active control - smart material and smart structure Supported by : National Natural Science Foundation of China (Grant No. 50025821)展开更多
The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimenta...The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimentary cover,was explored in order to evaluate the lithology and tectonics controls on its landscape usingthequalitativeandquantitative geomorphological analyses based on 30 m resolution Digital Elevation Models(DEM)and field evidences.This area displays an uneven and complex landscape differentiated into four morphological units:Douala,Nkondjock,Kumba and Buea Units.The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Camposedimentarybasin.The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement.The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau.The Buea Unit corresponds to the Mount Cameroon stratovolcano.The relief analysis through mountain-front sinuosity(Smf,1.19–1.43)and relative relief ratio(Rr,0.10–2.31)vary from one unit to another.The drainage network analysis including drainage patterns,stepped longitudinalriverprofiles,theassociated morphometric indexes,notably the concavity index(IC,0.56–0.88),deviation(D,267–2912 m),basin asymmetry factor(A_(F),6.37–42.12),hypsometric integral(HI,0.10–0.29),valley floor width to valley height ratio(V_(f),0.36–2.75),elongation ratio(R_(e),0.30–0.50),watershed slope(S,6.88–88.88)and stream length gradient index(SL,0–3332)vary from one basin to another too.These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics.The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points,asymmetric basins,and fault reactivations,and highlights the tectonics activity that used to occur through the time and their control on the morphology.Together,they document the lithostructural controls on the DBR landscape evolution,extendable in the whole SW Cameroon margin.展开更多
In this paper,a new system of semi active structural control with active variable stiffness and damping (AVSD) is suggested.This new system amplifies the structural displacement to dissipate more energy,and in turn,ef...In this paper,a new system of semi active structural control with active variable stiffness and damping (AVSD) is suggested.This new system amplifies the structural displacement to dissipate more energy,and in turn,effectively reduces the structural response in the case of relatively small story drifts,which occur during earthquakes.A predictive instantaneous optimal control algorithm is established for a SDOF structure equipped with an AVSD system Comparative shaking table tests of a 1/4 scale single story structural model with a full scale control device have been conducted.From the experimental and analytical results,it is shown that when compared to structures without control or with the active variable stiffness control alone, the suggested system exhibits higher efficiency in controlling the structural response,requires less energy input,operates with higher reliability,and can be manufactured at a lower cost and used in a wider range of engineering applications.展开更多
The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural...The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural trap. The mechanism has three major features: (1) timing of mineralization; (2) positioning of hostformation; and (3) dependence of ore-controlling structure on properties of rocks. The 'optimum surface' is adivisional structural plane which marks obvious difference in physical, chemical and mechanical properties andis favorable for mineralization. It is also a unity of structures. lithofacies and orebodies. The structural and geochemical characteristics of the ore deposits indicate the migration trend of the ma-jor characteristic clements in the ore-controlling fault belt: elements with a small radius (Si, Fe, Mg and Al)moved towards and concentrated at the center of the belt while large-radius ones (Ca, K and Na) were remotefrom the center.展开更多
The Olkaria geothermal field is located in the Kenya Rift valley, about 120 km from Nairobi. Geothermal activity is widespread in this rift with 14 major geothermal prospects being identified. Structures in the Greate...The Olkaria geothermal field is located in the Kenya Rift valley, about 120 km from Nairobi. Geothermal activity is widespread in this rift with 14 major geothermal prospects being identified. Structures in the Greater Olkaria volcanic complex include: the ring structure, the Ol’Njorowa gorge, the ENE-WSW Olkaria fault and N-S, NNE-SSW, NW-SE and WNW-ESE trending faults. The faults are more prominent in the East, Northeast and West Olkaria fields but are scarce in the Olkaria Domes area, possibly due to the thick pyroclastics cover. The NW-SE and WNW- ESE faults are thought to be the oldest and are associated with the development of the rift. The most prominent of these faults is the Gorge Farm fault, which bounds the geothermal fields in the northeastern part and extends to the Olkaria Domes area. The most recent structures are the N-S and the NNE-SSW faults. The geochemistry and output of the wells cut by these faults have a distinct characteristic that is the N-S, NW-SE and WNW-ESE faults are characterized by wells that have high Cl contents, temperatures and are good producers whereas the NE-SW faults, the Ring Structure and the Ol’Njorowa gorge appear to carry cool dilute waters with less chloride concentration and thus low performing wells. Though the impacts of these faults are apparent, there exists a gap in knowledge on how wide is the impact of these faults on the chemistry and performance of the wells. This paper therefore seeks to bridge this gap by analysis of the chemical trends of both old wells and newly drilled ones to evaluate the impacts of individual faults and then using buffering technique of ArcGis estimate how far and wide the influence of the faults is. The data was obtained after the sampling and analysis of discharge fluids of wells located on six profiles along the structures cutting through the field. Steam samples were collected with a stainless steel Webre separator connected between the wellhead and an atmospheric silencer on the discharging wells whereas the analysis was done in house in the KenGen geochemistry laboratory. The results indicates that Olkaria field has three categories of faults that control fluid flow that is the NW-SE trending faults that bring in high temperature and Cl rich waters, and the NE-SW trending Olkaria fracture tend to carry cool temperature waters that have led to decline in enthalpies of the wells it cuts through. The faults within the Ol Njorowa gorge act to carry cool, less mineralized water. Though initially, these effects were thought to be in shallow depths, an indication in OW-901 which is a deeper at 2200 m compared to 1600 m of OW-23 well that proves otherwise. This is, however, to be proved later as much deeper wells have been sited.展开更多
Xitian tin-polymetallic deposit, located in the eastern Hunan Province, SE China, hosts quartz vein and skarn in the contact zone between carbonate and two stages granites. Critical geodynamic questions for South Chin...Xitian tin-polymetallic deposit, located in the eastern Hunan Province, SE China, hosts quartz vein and skarn in the contact zone between carbonate and two stages granites. Critical geodynamic questions for South China are whether different types of mineralization form in the same time and how the magmatism–tectonic system controls the ore-forming process. Based on the distribution of the orebodies, six cassiterite samples from different types of mineralization are collected for dating. In-situ LA-MCICP-MS U–Pb isotopic data yielded concordia low intercept ages between 154 and 157 Ma, indicating that different types of mineralization belong to the same magmatism–mineralization system. Coupled with the study of the kinematic indicators, it suggests that the structural control of the wall rocks constrain the types of mineralization. These results provide further evidence of a close temporal link between the structure and the tin-polymetallic mineralization in Xitian deposit. Considering the structure in the district, granite dome plays an important role in the ore-forming process. The age and structural signatures in Xitian deposit are the response to the subduction of Pacific Plate.展开更多
In this paper,the strong structural controllability of the leader-follower framework is discussed.Firstly,the authors analyze different edge augmentation methods to preserve the strong structural controllability of th...In this paper,the strong structural controllability of the leader-follower framework is discussed.Firstly,the authors analyze different edge augmentation methods to preserve the strong structural controllability of the path-bud topology.The following four cases are considered:Adding edges from the path to the bud;adding edges from the bud to the path;adding the reverse or forward edges to the path or bud;and adding both the reverse and forward edges to the path or bud.Then sufficient conditions are derived for the strong structural controllability of the new topologies which are generated by adding different edges.In addition,it is proved that rank[A B]=n is a necessary condition for the strong structural controllability.Finally,three examples are given to verify the effectiveness of the main results.展开更多
This paper addresses the leader selection problem for strong structural controllability(SSC)of multi-agent systems(MASs). For a path-bud graph, it is proved that only one leader is required to guarantee the SSC of MAS...This paper addresses the leader selection problem for strong structural controllability(SSC)of multi-agent systems(MASs). For a path-bud graph, it is proved that only one leader is required to guarantee the SSC of MASs. For a special type of topologies, based on the partition of the topology into disjoint pathes and path-buds, it is proved that the MASs is strongly structurally controllable if the root nodes of the pathes are selected as leaders. For general topologies, an algorithm is provided to determine the agents that can behave as leaders. For some special topologies, the minimum number of leaders guaranteeing the robust strong structural controllability(RSSC) of MASs is also obtained.Two examples are given to verify the effectiveness of the results.展开更多
In 2011,Liu,et al.investigated the structural controllability of directed networks.They proved that the minimum number of input signals,driver nodes,can be determined by seeking a maximum matching in the directed netw...In 2011,Liu,et al.investigated the structural controllability of directed networks.They proved that the minimum number of input signals,driver nodes,can be determined by seeking a maximum matching in the directed network.Thus,the algorithm for seeking a maximum matching is the key to solving the structural controllability problem of directed networks.In this study,the authors provide algebraic expressions for matchings and maximum matchings proposed by Liu,et al.(2011)via a new matrix product called semi-tensor product,based on which the corresponding algorithms are established to seek matchings and maximum matchings in digraphs,which make determining the number of driver nodes tractable in computer.In addition,according to the proposed algorithm,the authors also construct an algorithm to distinguish critical arcs,redundant arcs and ordinary arcs of the directed network,which plays an important role in studying the robust control problem.An example of a small network from Liu’s paper is used for algorithm verification.展开更多
The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems....The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems. In this paper, studies of several EMD control strategies and bench-scale shaking table tests of a two-story model structure are described. First, two structural models corresponding to uncontrolled and Zeroed cases are developed, and parameters of these models are validated through sinusoidal sweep tests to provide a basis for establishing an accurate mathematical model for further studies. Then, a simplified control strategy for the EMD system based on the pole assignment control algorithm is proposed. Moreover, ideal pole locations are derived and validated through a series of shaking table tests. Finally, three benchmark earthquake ground motions and sinusoidal sweep waves are imposed onto the structure to investigate the effectiveness and feasibility of using this type of innovative active control system for structural vibration control. In addition, the robustness of the EMD system is examined. The test results show that the EMD system is an effective and robust system for the control of structural vibrations.展开更多
To track the rapidly changing temperature profiles of thermal cycling of polymerase chain reaction （PCR） accurately, an innovative feedforward variable structural proportional-integral-derivative （FVSPID） controll...To track the rapidly changing temperature profiles of thermal cycling of polymerase chain reaction （PCR） accurately, an innovative feedforward variable structural proportional-integral-derivative （FVSPID） controller was developed. Based on the step response test data of the heat block, a reduced first order model was estabfished at different operating points. Based on the reduced model, the FVSPID controller combined a feedforward path with the variable structural proportional-integral-derivative （PID） control. The modified feedforward action provided directly the optimal predictive power for the desired setpoint to speed up the dynamic response. To cooperate with the feedforward action, a variable structural PID was applied, where the P mode was used in the case of the largest errors to speed up response, whereas the PD mode was used in the case of larger errors to suppress overshoot, and finally the PID mode was applied for small error conditions to eliminate the steady state offset. Experimental results illustrated that compared to the conventional PID controller, the FVSPID controller can not only reduce the time taken to complete a standard PCR protocol, but also improve the accuracy of gene amplification.展开更多
A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) o...A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) of the cylindrical shell.Both global and local control strategies were considered.The optimal control forces corresponding to each control strategy were obtained by using the linear quadratic optimal control theory.Numerical simulations were performed to examine and analyze the control performance under different control strategies.The results show that global sound attenuation of the cylindrical shell at resonance frequencies can be achieved by using point force as the control input of the ASAC system.Better control performance can be obtained under the control strategy of minimization of the radiated sound power.However,control spillover may occur at off-resonance frequencies with the control strategy of structural kinetic energy minimization in terms of the radiated sound power.Considerable levels of global sound attenuation can also be achieved in the on-resonance cases with the local control strategy,i.e.,minimization of the mean-square velocity of finite discrete locations.An ASAC experiment using an FXLMS algorithm was implemented,agreement was observed between the numerical and experimental results,and successful attenuation of structural vibration and radiated sound was achieved.展开更多
Magneto-rheological visco-elastomer （MRVE） as a new smart material developed in recent years has several significant advantages over magneto-rheological liquid. The adjustability of structural dynamics to random env...Magneto-rheological visco-elastomer （MRVE） as a new smart material developed in recent years has several significant advantages over magneto-rheological liquid. The adjustability of structural dynamics to random environmental excitations is required in vibration control. MRVE can supply considerably adjustable damping and stiffness for structures, and the adjustment of dynamic properties is achieved only by applied magnetic fields with changeless structure design. Increasing researches on MRVE dy- namic properties, modeling, and vibration control application are presented. Recent advances in MRVE dynamic properties and structural vibration control application including composite structural vibration mitigation under uniform magnetic fields, vibration response characteristics improvement through harmonic parameter distribution, and optimal bounded parametric control design based on the dynamical programming principle are reviewed. Relevant main methods and results introduced are beneficial to understanding and researches on MRVE application and development.展开更多
Lung diseases associated with alveoli,such as acute respiratory distress syndrome,have posed a long-term threat to human health.However,an in vitro model capable of simulating different deformations of the alveoli and...Lung diseases associated with alveoli,such as acute respiratory distress syndrome,have posed a long-term threat to human health.However,an in vitro model capable of simulating different deformations of the alveoli and a suitable material for mimicking basement membrane are currently lacking.Here,we present an innovative biomimetic controllable strain membrane(BCSM)at an air–liquid interface(ALI)to reconstruct alveolar respiration.The BCSM consists of a high-precision three-dimensional printing melt-electrowritten polycaprolactone(PCL)mesh,coated with a hydrogel substrate—to simulate the important functions(such as stiffness,porosity,wettability,and ALI)of alveolar microenvironments,and seeded pulmonary epithelial cells and vascular endothelial cells on either side,respectively.Inspired by papercutting,the BCSM was fabricated in the plane while it operated in three dimensions.A series of the topological structure of the BCSM was designed to control various local-area strain,mimicking alveolar varied deformation.Lopinavir/ritonavir could reduce Lamin A expression under over-stretch condition,which might be effective in preventing ventilator-induced lung injury.The biomimetic lung-unit model with BCSM has broader application prospects in alveoli-related research in the future,such as in drug toxicology and metabolism.展开更多
This paper analyses the fragmenting principle of static blasting agent (SBA) and the action of its cutting fragmentation. Using SBA for sterming material proved very useful and advantageous. Here we analyse in detail ...This paper analyses the fragmenting principle of static blasting agent (SBA) and the action of its cutting fragmentation. Using SBA for sterming material proved very useful and advantageous. Here we analyse in detail the cutting action of pre- stress and stress wave in pre-stressing force blasting.展开更多
文摘Geothermal is a clean energy source that is freely available in the subsurface. The exploitation of this vital resource needs intensive exploration in order to identify and quantify its occurrence. The three parameters considered when assessing the viability of a geothermal system include;heat source, fractures and fluids. Geological structures are important in transportation of fluids to and from the heat source aiding in recharge of the geothermal system and enhancing productivity. Remote sensing method was applied in mapping the structures at Barrier Volcanic Complex (BVC) by using hill shading technique which utilized four illumination angles of the sun (azimuth) i.e. 45°, 90°, 150°, and 315°, constant elevation of 45° and exaggeration of 10. The data used was Shuttle Radar Topographic Mission (SRTM) Satellite Imagery. ArcGIS Software was used for lineaments delineation and density mapping, PCI Geomatica was used to generate major faults, while Georose and Rockworks 17 were used to generate the rose diagrams. Geological structural analysis was done by delineating lineaments, determining the density distribution of lineaments and finally determining the structural trends of lineaments. The generated major faults in the area and the location of the occurrence of surface manifestations were compared with the generated lineaments. A total of 260 lineaments were generated whereby at 45° there was a total of 60 lineaments, at 90° 95 lineaments, at 150° 61 lineaments, and at 315° 44 lineaments. The results of structural analysis in the area as shown by the rose diagrams indicate an NNE-SSW and N-S trending of structures. In conclusion, the study area is highly fractured as indicated by the presence of numerous lineaments. These lineaments provide good recharge to the geothermal system and enhance the geothermal reservoir in the area.
基金supported by start-up funds from the laboratory of H.WFaculty Sponsored Student Research Awards(FSSRA)from the Department of Chemistry and Biochemistry in the College of Science and Mathematics at California State University,Fresno。
文摘In addition to the tens of millions of medical doses consumed annually around the world,a vast number of nuclear magnetic resonance imaging(MRI)contrast agents are being deployed in MRI research and development,offering precise diagnostic information,targeting capabilities,and analyte sensing.Superparamagnetic iron oxide nanoparticles(SPIONs)are notable among these agents,providing effective and versatile MRI applications while also being heavy-metal-free,bioconjugatable,and theranostic.We designed and implemented a novel two-pronged computational and experimental strategy to meet the demand for the efficient and rigorous development of SPION-based MRI agents.Our MATLAB-based modeling simulation and magnetic characterization revealed that extremely small maghemite SPIONs in the 1-3 nm range possess significantly reduced transversal relaxation rates(R_(2))and are therefore preferred for positive(T_(1)-weighted)MRI.Moreover,X-ray diffraction and X-ray absorption fine structure analyses demonstrated that the diffraction pattern and radial distribution function of our SPIONs matched those of the targeted maghemite crystals.In addition,simulations of the X-ray near-edge structure spectra indicated that our synthesized SPIONs,even at 1 nm,maintained a spherical structure.Furthermore,in vitro and in vivo MRI investigations showed that our 1-nm SPIONs effectively highlighted whole-body blood vessels and major organs in mice and could be cleared through the kidney route to minimize potential post-imaging side effects.Overall,our innovative approach enabled a swift discovery of the desired SPION structure,followed by targeted synthesis,synchrotron radiation spectroscopic studies,and MRI evaluations.The efficient and rigorous development of our high-performance SPIONs can set the stage for a computational and experimental platform for the development of future MRI agents.
基金supported in part by the National Natural Science Foundation of China(U1808205,62173079)the Natural Science Foundation of Hebei Province of China(F2000501005)。
文摘This paper addresses the problem of the input design of large-scale complex networks.Two types of network components,redundant inaccessible strongly connected component(RISCC)and intermittent inaccessible strongly connected component(IISCC)are defined,and a subnetwork called a driver network is developed.Based on these,an efficient method is proposed to find the minimum number of controlled nodes to achieve structural complete controllability of a network,in the case that each input can act on multiple state nodes.The range of the number of input nodes to achieve minimal control,and the configuration method(the connection between the input nodes and the controlled nodes)are presented.All possible input solutions can be obtained by this method.Moreover,we give an example and some experiments on real-world networks to illustrate the effectiveness of the method.
文摘This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization. We first give an overview of natural phenomena of structurally-controlled ore formation and the background theory and mechanisms for such controls. We then provide the results of a group of simple 2D numerical models validated through comparison with Cu-vein structure observed near the Shilu Copper deposit （Yangchun, Guangdong Province, China） and finally a case study of 3D numerical modelling applied to the Hodgkinson Province in North Queensland （Australia）. Two modelling approaches, discrete deformation modelling and continuum coupled deformation and fluid flow modelling, are involved. The 2D model-derived patterns are remarkably consistent with the Cu-vein structure from the Shilu Copper deposit, and show that both modelling approaches can realistically simulate the mechanical behaviours of shear and dilatant fractures. The continuum coupled deformation and fluid flow model indicates that pattern of the Cu- veins near the Shilu deposit is the result of shear strain localization, development of dilation and fluid focussing into the dilatant fracture segments. The 3D case-study models （with deformation and fluid flow coupling） on the Hodgkinson Province generated a number of potential gold mineralization
文摘This paper focuses on how to determine the instantaneous damping of the semi-active tuned mass damper (SATMD) with continuously variable damping.An off-and-towards-equilibrium (OTE) algorithm is employed to examine the control performance of the structure/SATMD system by considering the damping as an assumptive control action.The damping modification of the SATMD is carried out according to the proposed OTE algorithm,which is formulated based on analysis of the structural movement under external excitations,and the measured responses of the structure at every time instant. As examples two numerical simulations of a five-storey and a ten-storey shear structures with a SATMD on the roof are conducted.The effectiveness on vibration reduction of MDOF systems subjected to seismic excitations is discussed.Analysis results show that the behavior of the structure with a SATMD is significantly improved and the feasibility of applying the OTE algorithm to the structural control design of SATMD is also verified.
基金National Natural Science Foundation of China Grant No.50025821
文摘The recent developments of theoretical research, model tests and engineering applications of structural control in China's Mainland are reviewed in this paper. It includes seismic isolation, passive energy dissipation, active and semi-active control, smart materials and smart structural systems. It can be seen that passive control methods, such as seismic isolation and energy dissipation methods, have developed into the mature stage in China. At the same time, great progress has been made in active and semi-active control, and smart actuators or smart dampers and smart structural systems. Finally, some future research initiatives for structural control in civil engineering are suggested. Keywords state-of-the-art review - structural control - seismic isolation - passive energy dissipation - active and semi-active control - smart material and smart structure Supported by : National Natural Science Foundation of China (Grant No. 50025821)
文摘The Douala-Buea Region(DBR;4°-5°N,9°-10°30’E),a portion of the southern Cameroon passive margin,developed on the Proterozoic granito-gneissic basement and the Cretaceous to Recent volcanosedimentary cover,was explored in order to evaluate the lithology and tectonics controls on its landscape usingthequalitativeandquantitative geomorphological analyses based on 30 m resolution Digital Elevation Models(DEM)and field evidences.This area displays an uneven and complex landscape differentiated into four morphological units:Douala,Nkondjock,Kumba and Buea Units.The Douala Unit corresponds to the Coastal Plain and is extended on the Douala-Kribi/Camposedimentarybasin.The Nkondjock Unit represents a middle plateau developed on a Proterozoic granito-gneissic basement.The Kumba Unit matches with the southernmost volcanic Western Cameroon High Plateau.The Buea Unit corresponds to the Mount Cameroon stratovolcano.The relief analysis through mountain-front sinuosity(Smf,1.19–1.43)and relative relief ratio(Rr,0.10–2.31)vary from one unit to another.The drainage network analysis including drainage patterns,stepped longitudinalriverprofiles,theassociated morphometric indexes,notably the concavity index(IC,0.56–0.88),deviation(D,267–2912 m),basin asymmetry factor(A_(F),6.37–42.12),hypsometric integral(HI,0.10–0.29),valley floor width to valley height ratio(V_(f),0.36–2.75),elongation ratio(R_(e),0.30–0.50),watershed slope(S,6.88–88.88)and stream length gradient index(SL,0–3332)vary from one basin to another too.These results also show the heterogeneous and uneven DBR landscape controlled by its lithology and active tectonics.The drainage system reveals concave to concavo-convex longitudinal river profile shapes with knick points,asymmetric basins,and fault reactivations,and highlights the tectonics activity that used to occur through the time and their control on the morphology.Together,they document the lithostructural controls on the DBR landscape evolution,extendable in the whole SW Cameroon margin.
文摘In this paper,a new system of semi active structural control with active variable stiffness and damping (AVSD) is suggested.This new system amplifies the structural displacement to dissipate more energy,and in turn,effectively reduces the structural response in the case of relatively small story drifts,which occur during earthquakes.A predictive instantaneous optimal control algorithm is established for a SDOF structure equipped with an AVSD system Comparative shaking table tests of a 1/4 scale single story structural model with a full scale control device have been conducted.From the experimental and analytical results,it is shown that when compared to structures without control or with the active variable stiffness control alone, the suggested system exhibits higher efficiency in controlling the structural response,requires less energy input,operates with higher reliability,and can be manufactured at a lower cost and used in a wider range of engineering applications.
文摘The ore-controlling mechanism of the bedding fault system in the massive sulfide deposits of the Wushancopper orefield may be generalized as the control of ore deposition by optimum surface in an ore-formingstructural trap. The mechanism has three major features: (1) timing of mineralization; (2) positioning of hostformation; and (3) dependence of ore-controlling structure on properties of rocks. The 'optimum surface' is adivisional structural plane which marks obvious difference in physical, chemical and mechanical properties andis favorable for mineralization. It is also a unity of structures. lithofacies and orebodies. The structural and geochemical characteristics of the ore deposits indicate the migration trend of the ma-jor characteristic clements in the ore-controlling fault belt: elements with a small radius (Si, Fe, Mg and Al)moved towards and concentrated at the center of the belt while large-radius ones (Ca, K and Na) were remotefrom the center.
文摘The Olkaria geothermal field is located in the Kenya Rift valley, about 120 km from Nairobi. Geothermal activity is widespread in this rift with 14 major geothermal prospects being identified. Structures in the Greater Olkaria volcanic complex include: the ring structure, the Ol’Njorowa gorge, the ENE-WSW Olkaria fault and N-S, NNE-SSW, NW-SE and WNW-ESE trending faults. The faults are more prominent in the East, Northeast and West Olkaria fields but are scarce in the Olkaria Domes area, possibly due to the thick pyroclastics cover. The NW-SE and WNW- ESE faults are thought to be the oldest and are associated with the development of the rift. The most prominent of these faults is the Gorge Farm fault, which bounds the geothermal fields in the northeastern part and extends to the Olkaria Domes area. The most recent structures are the N-S and the NNE-SSW faults. The geochemistry and output of the wells cut by these faults have a distinct characteristic that is the N-S, NW-SE and WNW-ESE faults are characterized by wells that have high Cl contents, temperatures and are good producers whereas the NE-SW faults, the Ring Structure and the Ol’Njorowa gorge appear to carry cool dilute waters with less chloride concentration and thus low performing wells. Though the impacts of these faults are apparent, there exists a gap in knowledge on how wide is the impact of these faults on the chemistry and performance of the wells. This paper therefore seeks to bridge this gap by analysis of the chemical trends of both old wells and newly drilled ones to evaluate the impacts of individual faults and then using buffering technique of ArcGis estimate how far and wide the influence of the faults is. The data was obtained after the sampling and analysis of discharge fluids of wells located on six profiles along the structures cutting through the field. Steam samples were collected with a stainless steel Webre separator connected between the wellhead and an atmospheric silencer on the discharging wells whereas the analysis was done in house in the KenGen geochemistry laboratory. The results indicates that Olkaria field has three categories of faults that control fluid flow that is the NW-SE trending faults that bring in high temperature and Cl rich waters, and the NE-SW trending Olkaria fracture tend to carry cool temperature waters that have led to decline in enthalpies of the wells it cuts through. The faults within the Ol Njorowa gorge act to carry cool, less mineralized water. Though initially, these effects were thought to be in shallow depths, an indication in OW-901 which is a deeper at 2200 m compared to 1600 m of OW-23 well that proves otherwise. This is, however, to be proved later as much deeper wells have been sited.
基金financially supported by the Public Welfare Project of the Ministry of land and Resources of China (201211024-04)National Key R&D Program of China (2016YFC0600401)+1 种基金National Science Foundation of China (NSFC Grant 41273046)Research Cooperation between Institute and University of Chinese Academy of Sciences Grant (Y552012Y00)
文摘Xitian tin-polymetallic deposit, located in the eastern Hunan Province, SE China, hosts quartz vein and skarn in the contact zone between carbonate and two stages granites. Critical geodynamic questions for South China are whether different types of mineralization form in the same time and how the magmatism–tectonic system controls the ore-forming process. Based on the distribution of the orebodies, six cassiterite samples from different types of mineralization are collected for dating. In-situ LA-MCICP-MS U–Pb isotopic data yielded concordia low intercept ages between 154 and 157 Ma, indicating that different types of mineralization belong to the same magmatism–mineralization system. Coupled with the study of the kinematic indicators, it suggests that the structural control of the wall rocks constrain the types of mineralization. These results provide further evidence of a close temporal link between the structure and the tin-polymetallic mineralization in Xitian deposit. Considering the structure in the district, granite dome plays an important role in the ore-forming process. The age and structural signatures in Xitian deposit are the response to the subduction of Pacific Plate.
基金supported by the National Natural Science Foundation of China under Grant Nos. 61873136 and 62033007Taishan Scholars Climbing Program of Shandong Province of ChinaTaishan Scholars Project of Shandong Province of China under Grant No. ts20190930
文摘In this paper,the strong structural controllability of the leader-follower framework is discussed.Firstly,the authors analyze different edge augmentation methods to preserve the strong structural controllability of the path-bud topology.The following four cases are considered:Adding edges from the path to the bud;adding edges from the bud to the path;adding the reverse or forward edges to the path or bud;and adding both the reverse and forward edges to the path or bud.Then sufficient conditions are derived for the strong structural controllability of the new topologies which are generated by adding different edges.In addition,it is proved that rank[A B]=n is a necessary condition for the strong structural controllability.Finally,three examples are given to verify the effectiveness of the main results.
基金supported by the National Natural Science Foundation of China under Grant Nos.61573105,61473081,61273110the Natural Science Foundation of Jiangsu Province under Grant No.BK20141341
文摘This paper addresses the leader selection problem for strong structural controllability(SSC)of multi-agent systems(MASs). For a path-bud graph, it is proved that only one leader is required to guarantee the SSC of MASs. For a special type of topologies, based on the partition of the topology into disjoint pathes and path-buds, it is proved that the MASs is strongly structurally controllable if the root nodes of the pathes are selected as leaders. For general topologies, an algorithm is provided to determine the agents that can behave as leaders. For some special topologies, the minimum number of leaders guaranteeing the robust strong structural controllability(RSSC) of MASs is also obtained.Two examples are given to verify the effectiveness of the results.
基金supported by the National Natural Science Foundation of China under Grant Nos.61573288,12071370,U1803263,71973103Key Programs in Shaanxi Province of China under Grant No.2021JZ-12。
文摘In 2011,Liu,et al.investigated the structural controllability of directed networks.They proved that the minimum number of input signals,driver nodes,can be determined by seeking a maximum matching in the directed network.Thus,the algorithm for seeking a maximum matching is the key to solving the structural controllability problem of directed networks.In this study,the authors provide algebraic expressions for matchings and maximum matchings proposed by Liu,et al.(2011)via a new matrix product called semi-tensor product,based on which the corresponding algorithms are established to seek matchings and maximum matchings in digraphs,which make determining the number of driver nodes tractable in computer.In addition,according to the proposed algorithm,the authors also construct an algorithm to distinguish critical arcs,redundant arcs and ordinary arcs of the directed network,which plays an important role in studying the robust control problem.An example of a small network from Liu’s paper is used for algorithm verification.
基金The National Natural Science Foundation of China Under Grant. No.50608026The National Major Foundamental Program (973 Program) of China Under Grant No. 2007CB714204
文摘The electromagnetic mass damper （EMD） control system, as an innovative active control system to reduce structural vibration, offers many advantages over traditional active mass driver/damper （AMD） control systems. In this paper, studies of several EMD control strategies and bench-scale shaking table tests of a two-story model structure are described. First, two structural models corresponding to uncontrolled and Zeroed cases are developed, and parameters of these models are validated through sinusoidal sweep tests to provide a basis for establishing an accurate mathematical model for further studies. Then, a simplified control strategy for the EMD system based on the pole assignment control algorithm is proposed. Moreover, ideal pole locations are derived and validated through a series of shaking table tests. Finally, three benchmark earthquake ground motions and sinusoidal sweep waves are imposed onto the structure to investigate the effectiveness and feasibility of using this type of innovative active control system for structural vibration control. In addition, the robustness of the EMD system is examined. The test results show that the EMD system is an effective and robust system for the control of structural vibrations.
基金Supported by the National Natural Science Foundation of China (No.60574038) and the Open Project Program of the State KeyLaboratory of Bioreactor Engineering/ECUST.
文摘To track the rapidly changing temperature profiles of thermal cycling of polymerase chain reaction （PCR） accurately, an innovative feedforward variable structural proportional-integral-derivative （FVSPID） controller was developed. Based on the step response test data of the heat block, a reduced first order model was estabfished at different operating points. Based on the reduced model, the FVSPID controller combined a feedforward path with the variable structural proportional-integral-derivative （PID） control. The modified feedforward action provided directly the optimal predictive power for the desired setpoint to speed up the dynamic response. To cooperate with the feedforward action, a variable structural PID was applied, where the P mode was used in the case of the largest errors to speed up response, whereas the PD mode was used in the case of larger errors to suppress overshoot, and finally the PID mode was applied for small error conditions to eliminate the steady state offset. Experimental results illustrated that compared to the conventional PID controller, the FVSPID controller can not only reduce the time taken to complete a standard PCR protocol, but also improve the accuracy of gene amplification.
基金Supported by the National Natural Science Foundation of China (No.10802024)Research Fund for the Doctoral Program of Higher Education of China (No. 200802171009)+2 种基金the Natural Science Foundation of Heilongjiang Province (No.E200944)Innovative Talents Fund of Harbin (No.2009RFQXG211)Fundamental Research Fund of HEU (No. HEUFT08003)
文摘A numerical and experimental study was presented on active control of structurally radiated sound from an elastic cylindrical shell.An analytical model was developed for the active structural acoustic control (ASAC) of the cylindrical shell.Both global and local control strategies were considered.The optimal control forces corresponding to each control strategy were obtained by using the linear quadratic optimal control theory.Numerical simulations were performed to examine and analyze the control performance under different control strategies.The results show that global sound attenuation of the cylindrical shell at resonance frequencies can be achieved by using point force as the control input of the ASAC system.Better control performance can be obtained under the control strategy of minimization of the radiated sound power.However,control spillover may occur at off-resonance frequencies with the control strategy of structural kinetic energy minimization in terms of the radiated sound power.Considerable levels of global sound attenuation can also be achieved in the on-resonance cases with the local control strategy,i.e.,minimization of the mean-square velocity of finite discrete locations.An ASAC experiment using an FXLMS algorithm was implemented,agreement was observed between the numerical and experimental results,and successful attenuation of structural vibration and radiated sound was achieved.
基金supported by the National Natural Science Foundation of China(11572279,11432012,and U1234210)the Zhejiang Provincial Natural Science Foundation of China(LY15A020001)the Hong Kong Polytechnic University Fund(1-BBY5)
文摘Magneto-rheological visco-elastomer （MRVE） as a new smart material developed in recent years has several significant advantages over magneto-rheological liquid. The adjustability of structural dynamics to random environmental excitations is required in vibration control. MRVE can supply considerably adjustable damping and stiffness for structures, and the adjustment of dynamic properties is achieved only by applied magnetic fields with changeless structure design. Increasing researches on MRVE dy- namic properties, modeling, and vibration control application are presented. Recent advances in MRVE dynamic properties and structural vibration control application including composite structural vibration mitigation under uniform magnetic fields, vibration response characteristics improvement through harmonic parameter distribution, and optimal bounded parametric control design based on the dynamical programming principle are reviewed. Relevant main methods and results introduced are beneficial to understanding and researches on MRVE application and development.
基金sponsored by the National Key Research and Development Program of China(2021YFC2501800)the National Natural Science Foundation of China(No.U1909218)the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.T2121004).
文摘Lung diseases associated with alveoli,such as acute respiratory distress syndrome,have posed a long-term threat to human health.However,an in vitro model capable of simulating different deformations of the alveoli and a suitable material for mimicking basement membrane are currently lacking.Here,we present an innovative biomimetic controllable strain membrane(BCSM)at an air–liquid interface(ALI)to reconstruct alveolar respiration.The BCSM consists of a high-precision three-dimensional printing melt-electrowritten polycaprolactone(PCL)mesh,coated with a hydrogel substrate—to simulate the important functions(such as stiffness,porosity,wettability,and ALI)of alveolar microenvironments,and seeded pulmonary epithelial cells and vascular endothelial cells on either side,respectively.Inspired by papercutting,the BCSM was fabricated in the plane while it operated in three dimensions.A series of the topological structure of the BCSM was designed to control various local-area strain,mimicking alveolar varied deformation.Lopinavir/ritonavir could reduce Lamin A expression under over-stretch condition,which might be effective in preventing ventilator-induced lung injury.The biomimetic lung-unit model with BCSM has broader application prospects in alveoli-related research in the future,such as in drug toxicology and metabolism.
文摘This paper analyses the fragmenting principle of static blasting agent (SBA) and the action of its cutting fragmentation. Using SBA for sterming material proved very useful and advantageous. Here we analyse in detail the cutting action of pre- stress and stress wave in pre-stressing force blasting.
