With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in...With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.展开更多
Osteoporosis represents a prevalent and debilitating comorbidity in patients diagnosed with type 2 diabetes mellitus(T2DM),which is characterized by suppressed osteoblast function and disrupted bone microarchitecture....Osteoporosis represents a prevalent and debilitating comorbidity in patients diagnosed with type 2 diabetes mellitus(T2DM),which is characterized by suppressed osteoblast function and disrupted bone microarchitecture.In this study,we utilized male C57BL/6 J mice to investigate the role of SIRT3 in T2DM.Decreased SIRT3 expression and impaired mitochondrial quality control mechanism are observed in both in vitro and in vivo models of T2DM.Mechanistically,SIRT3 suppression results in hyperacetylation of FOXO3,hindering the activation of the PINK1/PRKN mediated mitophagy pathway and resulting in accumulation of dysfunctional mitochondria.Genetical overexpression or pharmacological activation of SIRT3 restores deacetylation status of FOXO3,thus facilitating mitophagy and ameliorating osteogenic impairment in T2DM.Collectively,our findings highlight the fundamental regulatory function of SIRT3 in mitochondrial quality control,crucial for maintaining bone homeostasis in T2DM.These insights not only enhance our understanding of the molecular mechanisms underlying diabetic osteoporosis but also identify SIRT3 as a promising therapeutic target for diabetic osteoporosis.展开更多
Seepage flow through soils,rocks and geotechnical structures has a great influence on their stabilities and performances,and seepage control is a critical technological issue in engineering practices.The physical mech...Seepage flow through soils,rocks and geotechnical structures has a great influence on their stabilities and performances,and seepage control is a critical technological issue in engineering practices.The physical mechanisms associated with various engineering measures for seepage control are investigated from a new perspective within the framework of continuum mechanics;and an equation-based classification of seepage control mechanisms is proposed according to their roles in the mathematical models for seepage flow,including control mechanisms by coupled processes,initial states,boundary conditions and hydraulic properties.The effects of each mechanism on seepage control are illustrated with examples in hydroelectric engineering and radioactive waste disposal,and hence the reasonability of classification is demonstrated.Advice on performance assessment and optimization design of the seepage control systems in geotechnical engineering is provided,and the suggested procedure would serve as a useful guidance for cost-effective control of seepage flow in various engineering practices.展开更多
Flying insects are capable of flapping their wings to provide the required power and control forces for flight.A coordinated organizational system including muscles,wings,and control architecture plays a significant r...Flying insects are capable of flapping their wings to provide the required power and control forces for flight.A coordinated organizational system including muscles,wings,and control architecture plays a significant role,which provides the sources of inspiration for designing flapping-wing vehicles.In recent years,due to the development of micro-and meso-scale manufacturing technologies,advances in components technologies have directly led to a progress of smaller Flapping-Wing Nano Air Vehicles(FWNAVs)around gram and sub-gram scales,and these air vehicles have gradually acquired insect-like locomotive strategies and capabilities.This paper will present a selective review of components technologies for ultra-lightweight flapping-wing nano air vehicles under 3 g,which covers the novel propulsion methods such as artificial muscles,flight control mechanisms,and the design paradigms of the insect-inspired wings,with a special focus on the development of the driving technologies based on artificial muscles and the progress of the biomimetic wings.The challenges involved in constructing such small flapping-wing air vehicles and recommendations for several possible future directions in terms of component technology enhancements and overall vehicle performance are also discussed in this paper.This review will provide the essential guidelines and the insights for designing a flapping-wing nano air vehicle with higher performance.展开更多
According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM wel...According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.展开更多
Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qingha...Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qinghai Lake,the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics,development patterns,sand control factors,and hydrocarbon accumulation characteristics.Beach-bar sand bodies are widely developed in the Neogene saline lake basin,and they are lithologically fine sandstone and siltstone,with wavy bedding,low-angle cross bedding,and lenticular-vein bedding.In view of spatial-temporal distribution,the beach-bar sand bodies are stacked in multiple stages vertically,migratory laterally,and extensive and continuous in NW-SE trending pattern in the plane.The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km^(2).The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone,and the debris input from the source area affects the scale and enrichment of beach-bar sandstone.The ancient landform controls the morphology and stacking style of beach-bar sandstone,and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone.The beach-bars have a reservoir-forming feature of“one reservoir in one sand body”,with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction.Three favorable exploration target zones in Zhahaquan,Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.展开更多
The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism,...The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.展开更多
The mutual control mechanism between magnetization and polarization in multiferroic materials is studied. The system contains a ferromagnetic sublattice and a ferroelectric sublattice. To describe the magneto–electri...The mutual control mechanism between magnetization and polarization in multiferroic materials is studied. The system contains a ferromagnetic sublattice and a ferroelectric sublattice. To describe the magneto–electric coupling, we propose a linear coupling Hamiltonian between ferromagnetism and ferroelectricity without microscopic derivation. This coupling enables one to retrieve the hysteresis loops measured experimentally. The thermodynamic properties of the system are calculated, such as the temperature dependences of the magnetization, polarization, internal energy and free energy.The ferromagnetic and ferroelectric hysteresis loops driven by either a magnetic or an electric field are calculated, and the magnetic spin and pseudo-spin are always flipped synchronously under the external magnetic and electric field. Our theoretical results are in agreement with the experiments.展开更多
A new vapor distributor based on the Coanda effect is added to the Dividing Wall column(DWC),and the multiphase flow simulation is performed using ANSYS Fluent by this model.The results show that with the addition of ...A new vapor distributor based on the Coanda effect is added to the Dividing Wall column(DWC),and the multiphase flow simulation is performed using ANSYS Fluent by this model.The results show that with the addition of the liquid phase,the new vapor distributor still follows the Coanda effect.Hereby,the vapor is ejected from the slits of the distributor to take away the surrounding vapor,and a negative pressure is formed under the distributor,so as to achieve the purpose of regulating Rv.Analogously to the working principle of vapor distributor,a certain amount of vapor is drawn out from a position of prefractionator,which is equivalent to the vapor ejected by the distributor.The same amount of vapor is fed into the main column,which corresponds to the gas phase at the inlet of the distributor.The Rv is adjusted by changing the speed of the input or output vapor.Simulation results show that adding this control mechanism on the basis of temperature or concentration control structure can better achieve the effect of vapor distribution.展开更多
In view of the problems found in the in-depth interviews of the current situation of rural non-point source pollution control mechanism in Nantong City and their reasons,the following six countermeasures and suggestio...In view of the problems found in the in-depth interviews of the current situation of rural non-point source pollution control mechanism in Nantong City and their reasons,the following six countermeasures and suggestions are put forward,including giving full play to the role of fighting bastion of the Party branch and building a mechanism for Party building to lead the control of non-point source pollution in rural areas,giving prominence to the dominant role of farmers and establishing farmers’endogenous motivation excitation mechanism for rural non-point source pollution control,improving the interest coordination mechanism among multiple governance subjects and building a modern control system for rural non-point source pollution,combining regulations,administrative,economic,technical and other means of rural non-point source pollution control and strengthening the synergistic integration mechanism of multiple means of control,reconstructing the information disclosure mechanism of rural non-point source pollution control and building a comprehensive trust mechanism of multiple control subjects,and improving the mechanism for coordinating the supply of policy tools and ensure that basic mechanisms play their due role.展开更多
According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems....According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.展开更多
In the 21st century, especially after the accession to WTO, Construction project bidding price formation mechanism is the main characteristics of the market price of the Construction project is divided in a unified, u...In the 21st century, especially after the accession to WTO, Construction project bidding price formation mechanism is the main characteristics of the market price of the Construction project is divided in a unified, uniform measurement unit, unified in terms of engineering and consumption of fixed rules on the basis of the implementation of market, competition fees.The first to be carried out not only the financial decision-making, corporate contractors in accordance with the different ways, according to market conditions, its technology, economic strength, through the financial decision-making self-quotation. Second, it is necessary to exercise effective control, both the Construction project bidding price by the form of the contract price is fixed.By design, material procurement, construction management on the implementation of bidding for the effective control of prices.展开更多
In the present research work, the pitch-control is carried out such that the rotor blades are rotated around their longitudinal axis while the rotor continues its normal rotation. It is really a challenge to produce a...In the present research work, the pitch-control is carried out such that the rotor blades are rotated around their longitudinal axis while the rotor continues its normal rotation. It is really a challenge to produce a clever design to pitch the rotor blades by the optimal amount so as to maximize the power output at all wind speeds. The mechanism is implemented to a three-blade, horizontal-axis, home-scale wind turbine. The mechanism is powered by a suitable DC （direct-current） motor. The tests were carried out in the open section of a delivery wind tunnel. The air speed was measured by a suitable anemometer. The corresponding rotational speed （rpm） and output voltage at different wind speeds were measured and recorded for calibration of the control system. The mechanism proved to be successful in controlling the pitch angle over a wide range of wind speeds.展开更多
Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements whe...Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements when working in complex terrains such as field stubble,waterlogged silt,and loose/firm terrain.These differentiated dynamics prevent cooperation between ETs and operating implements under independent control,resulting in poor quality operations and low energy efficiency.We propose a control mechanism for ETs and implements to achieve full life cycle management of collaborative control tasks,instantaneous intertask interaction,and a multitask synchronization mechanism.To address the internal redundant communication problems caused by traditional distributed microcontrol units,we break through the underlying technology of unit data processing and interaction and develop an integrated high-performance controller structure with high processing capacity and high-and low-speed communication interfaces.On the basis of hierarchical stepwise control theory,a hierarchical real-time operating system is designed.This system realizes a preemptive kernel response of computational tasks and competitive-collaborative synchronization among tasks;overcomes the low-latency response of collaborative control tasks,instantaneous information interaction,and multitask synchronization problems;and provides system-level support for deep collaborative operation control of units.To demonstrate and validate the proposed collaborative control mechanism,a plowing collaborative operation management strategy is designed and deployed.The experimental results show that the communication delay of collaborative tasks is as low as 83μs,the solution time of complex collaborative equations is as low as 46 ms,the mechanical efficiency of the ET is increased by 9.07%,the efficiency of the drive motor is increased by 9.72%,the stability of the operation speed is increased by 106.25%,and the stability of the plowing depth reaches 94.98%.Our work meets the hardware and software requirements for realizing complex collaborative control of ET units and improves the operational quality and operational energy efficiency in real vehicle demonstrations.展开更多
Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of con...Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of continental shale oil reservoir.The Chang 72continental shale was used to investigate the mechanical properties of laminations and the effect of natural structure on the crack propagation of the shale.The XRD and thin section tests show that the laminations contain two types:bright sandy lamination with void structure and dark muddy lamination with layer structure.The real-time CT uniaxial compression tests were conducted to investigate the differences of mechanical properties between the muddy lamination and sandy lamination.It found that the uniaxial compression strength and elastic modulus of the sandy lamination are higher,forming a simple crack with large opening,and the Poisson's ratio of the muddy lamination is large,forming obvious lateral deformation and more secondary cracks.On this basis,the cuboid-shaped continental shale specimens were tested under true triaxial compression conditions to study the effect of laminations and interface cracks on crack propagation combining AE and CT techniques.It found that nascent cracks connected laminations and interface cracks to form fracture network under appropriate loading condition,tensile cracks developed in sandy lamination and shear cracks occurred in muddy lamination because of deformation dissonance and brittleness index differences,and more secondary cracks formed in muddy lamination with smaller fracture toughness.Moreover,the combination relationships between nascent and natural cracks mainly conclude direct penetration and deflection,which is affected by the filling degree and morphology of interface cracks and the relationship of lamination types.These conclusions show that laminar continental shale is conducive to forming complex fracture network,which can provide a theoretical basis for the proposal of indicators and methods for fracability evaluation.展开更多
Objective:To characterize mosquito larval habitats and the influence of meteorological factors on their prevalence,and to suggest alternatives for vector control in Makkah Al-Mukarramah.Methods:A mosquito survey was c...Objective:To characterize mosquito larval habitats and the influence of meteorological factors on their prevalence,and to suggest alternatives for vector control in Makkah Al-Mukarramah.Methods:A mosquito survey was conducted within the 16 municipalities of Makkah Al-Mukarramah,from November 2022 to October 2023.The characteristics of larval habitats used by all reported species as oviposition sites were determined.Seasonal house,container,and breteau indices were used to determine larval abundance.Results:16 Species belonging to five genera[Aedes(3 spp.),Anopheles(3 spp.),Culex(8 spp.),Culiseta(1 sp.),and Lutzia(1 sp.)]were collected.A total of 185608 potential mosquito larval habitats were surveyed.Of these,95853(67.4%)were Aedes,45522(32%)were Culex,718(0.5%)were Anopheles,and 38(0.03%)were other species;154726(83.4%)were water sources for mosquito larvae,and among these sources,7663(5.0%)were positive for larvae,with 45.9%indoors and 54.1%outdoors.Most of the positive larval habitats were recorded in Al-Shawqiya(1093,14.3%),Al-Sharayia(1003,13.1%)and Al-Umrah(984,12.8%).A total of 142131 mosquito larvae and pupae were collected.The majority number of positive residences for all mosquito larvae was observed in January 2023(1658,21.6%).Conclusions:New appropriate alternatives for vector control are proposed,such as mechanical,biological,and environmental control.展开更多
The strategy of modeling the control mechanism for generating F0 contour of speech signal is studied in this paper. Based on some dynamic characteristics of vocal cord strain, the complex laryngeal mechanism relative ...The strategy of modeling the control mechanism for generating F0 contour of speech signal is studied in this paper. Based on some dynamic characteristics of vocal cord strain, the complex laryngeal mechanism relative to local F0 regulation is simplified to be a feasible physical model. Furthermore, a model function is deduced as the control mechanism for the generation process of local rise-fall patterns, and two kinds of basic feature patterns result with so called rise-fall commands defined by model parameters. on the logarithmic scale of F0 versus time the local characteristics of an F0 contour are approximated by the sum of these patterns generated by appropriate commands. The experimenial results in analyzing and synthesizing the F0 contours of spoken Chinese utterances indicate that the observed F0 contours can be always approximated well by the model, and a good correlation exists between some model parameters and the transition duration of local F0 rising or falling. The model lays a foundation for Chinese F0 contour synthesis by rule.展开更多
An analytical study was presented on active control of sound transmission into a vibro-acoustic enclosure comprising two flexible plates. Two types of actuators were used, i.e. acoustic actuator and distributed lead z...An analytical study was presented on active control of sound transmission into a vibro-acoustic enclosure comprising two flexible plates. Two types of actuators were used, i.e. acoustic actuator and distributed lead zirconate titanate piezoelectric (PZT) actuator instead of point force actuator. Using the modal acoustic transfer impedance-mobility matrices, the excitation and interaction in the coupled sound transmission system can be described with clear physical significance. With the control system designed to globally reduce the sound field, different control system configurations were considered, including the structural actuator on the incident plate, actuator on the receiving plate, acoustic actuator on the cavity, and their combinations. The effectiveness and performance of the control strategy corresponding to each system configuration were compared and discussed. The role and control mechanism of each type of actuator were of particular interest. It was shown that the incident plate actuator is effective in controlling the cavity-dominated modes and the structural modes dominated by the incident plate and receiving plate. Two main control mechanisms are involved in this control configuration, i.e., modal suppressing and modal rearrangement. For control system configuration with only acoustic actuator in the enclosure, the mechanism involved in this arrangement is purely modal suppression. Desirable placements of structural actuators in terms of total potential energy reduction were also discussed.展开更多
A complex object is an abstraction and description of a complex entity of the real world. Many applications in such domains as CIMS, CAD and OA define and manipulate a complex object as a single unit. In this paper, a...A complex object is an abstraction and description of a complex entity of the real world. Many applications in such domains as CIMS, CAD and OA define and manipulate a complex object as a single unit. In this paper, a definition of the model of complex objects is given, and the concurrency control mechanism of complex objects in WHYMX object-oriented database system is described.展开更多
Design and implementation of an effective control mechanism is the key to enable the controlledflight of flapping wing rotor micro aerial vehicles(FWR-MAVs).In order to address this open challenge,in this paper,a trip...Design and implementation of an effective control mechanism is the key to enable the controlledflight of flapping wing rotor micro aerial vehicles(FWR-MAVs).In order to address this open challenge,in this paper,a triple-wing FWR-MAV with its particular control system is proposed.The corresponding experimental study of the vehicle is conducted.As a result,the triple-wing propulsion system demonstrates advantages in both lift generation and flight stability based on the force measurement.The control torques of the proposed FWR-MAV are generated by a particular slipflow rudder mechanism.The effectiveness of such a design combination has been validated experimentally.A series of flight tests are conducted,including sustained hovering and forward-backward maneuvering.To the best of our knowledge,such a design yields the world's first FWR-MAV capable of sustained controlled flight.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.42477166 and 42277174)+2 种基金the Fundamental Research Funds for the Central Universities,China(No.2024JCCXSB01)the Opening Project of State Key Laboratory of Explosion Science and Safety Protection,Beijing Institute of Technology(No.KFJJ24-01M)the Open Foundation of Collaborative Innovation Center of Green Development and Ecological Restoration of Mineral Resources(No.HLCX2024-04)。
文摘With resource exploitation and engineering construction gradually going deeper,the surrounding rock dynamic disaster becomes frequent and violent.The anchorage support is a common control method of surrounding rock in underground engineering.To study the dynamic damage characteristics of anchored rock and the energy absorption control mechanism of dynamic disasters,a new type of constant resistance and energy absorption(CREA)material with high strength,high elongation and high energy absorption characteristics is developed.A contrast test of rockbursts in anchored rock with different support materials is conducted.The test results show that the surface damage rates and energy release degree of anchored rock with common bolt(CB)and CREA are lower than those of unanchored rock,respectively.The total energy,average energy and maximum energy released by CREA anchored rock are 30.9%,94.3%and 84.4%lower than those of CB anchored rock.Compared with unanchored rock,the rockburst peak stress in the CREA anchored rock is increased by 39.9%,and the rockburst time is delayed by 53.2%.Based on the rockburst energy calculation model,the evolution law of rockburst peak stress and energy release is investigated.The control mechanism of CREA support units on rock dynamic failure is clarified.
基金supported by the National Key Research and Development Project (2021YFA1201404)National Natural Science Foundation of China Major Project (81991514)+6 种基金General Project (82272530, 82372459)Jiangsu Province Medical Innovation Center of Orthopedic Surgery (CXZX202214)Jiangsu Provincial Key Medical Center FoundationJiangsu Provincial Medical Outstanding Talent FoundationJiangsu Provincial Medical Youth Talent FoundationJiangsu Provincial Key Medical Talent Foundationthe Fundamental Research Funds for the Central Universities (14380493, 14380494)
文摘Osteoporosis represents a prevalent and debilitating comorbidity in patients diagnosed with type 2 diabetes mellitus(T2DM),which is characterized by suppressed osteoblast function and disrupted bone microarchitecture.In this study,we utilized male C57BL/6 J mice to investigate the role of SIRT3 in T2DM.Decreased SIRT3 expression and impaired mitochondrial quality control mechanism are observed in both in vitro and in vivo models of T2DM.Mechanistically,SIRT3 suppression results in hyperacetylation of FOXO3,hindering the activation of the PINK1/PRKN mediated mitophagy pathway and resulting in accumulation of dysfunctional mitochondria.Genetical overexpression or pharmacological activation of SIRT3 restores deacetylation status of FOXO3,thus facilitating mitophagy and ameliorating osteogenic impairment in T2DM.Collectively,our findings highlight the fundamental regulatory function of SIRT3 in mitochondrial quality control,crucial for maintaining bone homeostasis in T2DM.These insights not only enhance our understanding of the molecular mechanisms underlying diabetic osteoporosis but also identify SIRT3 as a promising therapeutic target for diabetic osteoporosis.
基金Supported by the National Natural Science Foundation of China(51079107,50839004)the Program for New Century Excellent Talents in University(NCET-09-0610)
文摘Seepage flow through soils,rocks and geotechnical structures has a great influence on their stabilities and performances,and seepage control is a critical technological issue in engineering practices.The physical mechanisms associated with various engineering measures for seepage control are investigated from a new perspective within the framework of continuum mechanics;and an equation-based classification of seepage control mechanisms is proposed according to their roles in the mathematical models for seepage flow,including control mechanisms by coupled processes,initial states,boundary conditions and hydraulic properties.The effects of each mechanism on seepage control are illustrated with examples in hydroelectric engineering and radioactive waste disposal,and hence the reasonability of classification is demonstrated.Advice on performance assessment and optimization design of the seepage control systems in geotechnical engineering is provided,and the suggested procedure would serve as a useful guidance for cost-effective control of seepage flow in various engineering practices.
基金supported by the National Natural Science Foundation of China(Nos.52175277,51905431).
文摘Flying insects are capable of flapping their wings to provide the required power and control forces for flight.A coordinated organizational system including muscles,wings,and control architecture plays a significant role,which provides the sources of inspiration for designing flapping-wing vehicles.In recent years,due to the development of micro-and meso-scale manufacturing technologies,advances in components technologies have directly led to a progress of smaller Flapping-Wing Nano Air Vehicles(FWNAVs)around gram and sub-gram scales,and these air vehicles have gradually acquired insect-like locomotive strategies and capabilities.This paper will present a selective review of components technologies for ultra-lightweight flapping-wing nano air vehicles under 3 g,which covers the novel propulsion methods such as artificial muscles,flight control mechanisms,and the design paradigms of the insect-inspired wings,with a special focus on the development of the driving technologies based on artificial muscles and the progress of the biomimetic wings.The challenges involved in constructing such small flapping-wing air vehicles and recommendations for several possible future directions in terms of component technology enhancements and overall vehicle performance are also discussed in this paper.This review will provide the essential guidelines and the insights for designing a flapping-wing nano air vehicle with higher performance.
基金financial support from the various funding agencies including the Major State Basic Research Development Program of China (973 Program, 2009CB219604)the National Natural Science Foundation of China (41272175)+1 种基金the Key Project of the National Science & Technology (2011ZX05034-001)the China Scholarship Council
文摘According to dimensionless analysis of the coalbed methane （CBM） production data of Fanzhuang block in southern Qinshui basin, the dimensionless gas production rate is calculated to quantitatively divide the CBM well production process into four stages, i.e., drai- nage stage, unstable gas production stage, stable gas pro- duction stage, and gas production decline stage. By the material balance method, the coal reservoir permeability change in different stages is quantitatively characterized. The characteristics and control mechanisms of change in coalbed permeability （CICP） during different production stages are concluded on five aspects, i.e., permeability trend variation, controlling mechanism, system energy, phase state compositions, and production performance. The study reveals that CICP is characterized by first decline, then recovery, and finally by increase and is controlled directly by effective stress and matrix shrinkage effects. Further, the duration and intensity of the matrix shrinkage effect are inherently controlled by adsorption and desorp- tion features.
基金Supported by the PetroChina Science and Technology Project (2021DJ0402,2021DJ0202)。
文摘Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qinghai Lake,the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics,development patterns,sand control factors,and hydrocarbon accumulation characteristics.Beach-bar sand bodies are widely developed in the Neogene saline lake basin,and they are lithologically fine sandstone and siltstone,with wavy bedding,low-angle cross bedding,and lenticular-vein bedding.In view of spatial-temporal distribution,the beach-bar sand bodies are stacked in multiple stages vertically,migratory laterally,and extensive and continuous in NW-SE trending pattern in the plane.The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km^(2).The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone,and the debris input from the source area affects the scale and enrichment of beach-bar sandstone.The ancient landform controls the morphology and stacking style of beach-bar sandstone,and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone.The beach-bars have a reservoir-forming feature of“one reservoir in one sand body”,with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction.Three favorable exploration target zones in Zhahaquan,Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.
文摘The control mechanism of mechanical bone remodeling at cellular level was investigated by means of an extensive parametric study on a theoretical model described in this paper. From a perspective of control mechanism, it was found that there are several control mechanisms working simultaneously in bone remodeling which is a complex process. Typically, an extensive parametric study was carried out for investigating model parameter space related to cell differentiation and apoptosis which can describe the fundamental cell lineage behaviors. After analyzing all the combinations of 728 permutations in six model parameters, we have identified a small number of parameter combinations that can lead to physiologically realistic responses which are similar to theoretically idealized physiological responses. The results presented in the work enhanced our understanding on mechanical bone remodeling and the identified control mechanisms can help researchers to develop combined pharmacological-mechanical therapies to treat bone loss diseases such as osteoporosis.
基金supported by the National Basic Research Program of China(Grant No.2012CB927402)the National Natural Science Foundation of China(Grant Nos.61275028 and 11074145)
文摘The mutual control mechanism between magnetization and polarization in multiferroic materials is studied. The system contains a ferromagnetic sublattice and a ferroelectric sublattice. To describe the magneto–electric coupling, we propose a linear coupling Hamiltonian between ferromagnetism and ferroelectricity without microscopic derivation. This coupling enables one to retrieve the hysteresis loops measured experimentally. The thermodynamic properties of the system are calculated, such as the temperature dependences of the magnetization, polarization, internal energy and free energy.The ferromagnetic and ferroelectric hysteresis loops driven by either a magnetic or an electric field are calculated, and the magnetic spin and pseudo-spin are always flipped synchronously under the external magnetic and electric field. Our theoretical results are in agreement with the experiments.
基金This work was supported by the National Natural Science Foundation of China(21878066).
文摘A new vapor distributor based on the Coanda effect is added to the Dividing Wall column(DWC),and the multiphase flow simulation is performed using ANSYS Fluent by this model.The results show that with the addition of the liquid phase,the new vapor distributor still follows the Coanda effect.Hereby,the vapor is ejected from the slits of the distributor to take away the surrounding vapor,and a negative pressure is formed under the distributor,so as to achieve the purpose of regulating Rv.Analogously to the working principle of vapor distributor,a certain amount of vapor is drawn out from a position of prefractionator,which is equivalent to the vapor ejected by the distributor.The same amount of vapor is fed into the main column,which corresponds to the gas phase at the inlet of the distributor.The Rv is adjusted by changing the speed of the input or output vapor.Simulation results show that adding this control mechanism on the basis of temperature or concentration control structure can better achieve the effect of vapor distribution.
基金Supported by the Project for Philosophy and Social Science Research of Colleges and Universities in Jiangsu(2019SJA1539)Excellent Teaching Team of"Qinglan Project"of Colleges and Universities in Jiangsu(Sujiaoshihan[2020]No.10)+4 种基金Innovation and Entrepreneurship Training Planning Project for University Students in Jiangsu Province(202112684014Y)Construction Project of High-level Professional Group of Environmental Engineering Technology in Higher Vocational Education of Jiangsu Province(Sujiaozhihan[2020]No.31)Construction Project of Industry-Education Integration Platform in Jiangsu Province"Industry-Education Integration Platform of Ecological Environmental Protection and Control"(Sujiaozhihan[2019]No.26)Jiangsu Province Engineering Research Center of Agricultural and Rural Pollution Prevention Technology and Equipment(Sufagaigaojifa[2022]No.1103)School Talent Team Project(Tongkexiao[2021]No.10)。
文摘In view of the problems found in the in-depth interviews of the current situation of rural non-point source pollution control mechanism in Nantong City and their reasons,the following six countermeasures and suggestions are put forward,including giving full play to the role of fighting bastion of the Party branch and building a mechanism for Party building to lead the control of non-point source pollution in rural areas,giving prominence to the dominant role of farmers and establishing farmers’endogenous motivation excitation mechanism for rural non-point source pollution control,improving the interest coordination mechanism among multiple governance subjects and building a modern control system for rural non-point source pollution,combining regulations,administrative,economic,technical and other means of rural non-point source pollution control and strengthening the synergistic integration mechanism of multiple means of control,reconstructing the information disclosure mechanism of rural non-point source pollution control and building a comprehensive trust mechanism of multiple control subjects,and improving the mechanism for coordinating the supply of policy tools and ensure that basic mechanisms play their due role.
基金supported by the National High Technology Research and Development Program ("863" Program) of China under Grant No. 2007AA01Z209the National Basic Research Program of China under Grant No. 2009CB320405.
文摘According to the basic functions and objectives of Cognitive Radio (CR) systems, the cognition-based adaptive control mechanism is the generalization of the research contents and approaches of cognitive radio systems. Therefore, the mechanism is described by a cognition loop, which contains the following parts: environment, inner structure of intelligent systems, observation and action.
文摘In the 21st century, especially after the accession to WTO, Construction project bidding price formation mechanism is the main characteristics of the market price of the Construction project is divided in a unified, uniform measurement unit, unified in terms of engineering and consumption of fixed rules on the basis of the implementation of market, competition fees.The first to be carried out not only the financial decision-making, corporate contractors in accordance with the different ways, according to market conditions, its technology, economic strength, through the financial decision-making self-quotation. Second, it is necessary to exercise effective control, both the Construction project bidding price by the form of the contract price is fixed.By design, material procurement, construction management on the implementation of bidding for the effective control of prices.
文摘In the present research work, the pitch-control is carried out such that the rotor blades are rotated around their longitudinal axis while the rotor continues its normal rotation. It is really a challenge to produce a clever design to pitch the rotor blades by the optimal amount so as to maximize the power output at all wind speeds. The mechanism is implemented to a three-blade, horizontal-axis, home-scale wind turbine. The mechanism is powered by a suitable DC （direct-current） motor. The tests were carried out in the open section of a delivery wind tunnel. The air speed was measured by a suitable anemometer. The corresponding rotational speed （rpm） and output voltage at different wind speeds were measured and recorded for calibration of the control system. The mechanism proved to be successful in controlling the pitch angle over a wide range of wind speeds.
基金supported by the National Key Research and Development Plan of China(2022YFD2001202)the National Natural Science Foundation of China(32301719 and 52272444)the 2115 Talent Development Program of China Agricultural University.
文摘Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements when working in complex terrains such as field stubble,waterlogged silt,and loose/firm terrain.These differentiated dynamics prevent cooperation between ETs and operating implements under independent control,resulting in poor quality operations and low energy efficiency.We propose a control mechanism for ETs and implements to achieve full life cycle management of collaborative control tasks,instantaneous intertask interaction,and a multitask synchronization mechanism.To address the internal redundant communication problems caused by traditional distributed microcontrol units,we break through the underlying technology of unit data processing and interaction and develop an integrated high-performance controller structure with high processing capacity and high-and low-speed communication interfaces.On the basis of hierarchical stepwise control theory,a hierarchical real-time operating system is designed.This system realizes a preemptive kernel response of computational tasks and competitive-collaborative synchronization among tasks;overcomes the low-latency response of collaborative control tasks,instantaneous information interaction,and multitask synchronization problems;and provides system-level support for deep collaborative operation control of units.To demonstrate and validate the proposed collaborative control mechanism,a plowing collaborative operation management strategy is designed and deployed.The experimental results show that the communication delay of collaborative tasks is as low as 83μs,the solution time of complex collaborative equations is as low as 46 ms,the mechanical efficiency of the ET is increased by 9.07%,the efficiency of the drive motor is increased by 9.72%,the stability of the operation speed is increased by 106.25%,and the stability of the plowing depth reaches 94.98%.Our work meets the hardware and software requirements for realizing complex collaborative control of ET units and improves the operational quality and operational energy efficiency in real vehicle demonstrations.
基金funded by the National Natural Science Foundation of China(42102309 and 42007243)the Natural Science Foundation of Liaoning Province(2023-MSBA-120)the National Key Research and Development Program(2022YFB3304705)。
文摘Clarify the mechanical properties of different laminations and the fracture mechanism of continental shale under in-situ stress can provide theoretical basis for more comprehensive evaluation of the fracability of continental shale oil reservoir.The Chang 72continental shale was used to investigate the mechanical properties of laminations and the effect of natural structure on the crack propagation of the shale.The XRD and thin section tests show that the laminations contain two types:bright sandy lamination with void structure and dark muddy lamination with layer structure.The real-time CT uniaxial compression tests were conducted to investigate the differences of mechanical properties between the muddy lamination and sandy lamination.It found that the uniaxial compression strength and elastic modulus of the sandy lamination are higher,forming a simple crack with large opening,and the Poisson's ratio of the muddy lamination is large,forming obvious lateral deformation and more secondary cracks.On this basis,the cuboid-shaped continental shale specimens were tested under true triaxial compression conditions to study the effect of laminations and interface cracks on crack propagation combining AE and CT techniques.It found that nascent cracks connected laminations and interface cracks to form fracture network under appropriate loading condition,tensile cracks developed in sandy lamination and shear cracks occurred in muddy lamination because of deformation dissonance and brittleness index differences,and more secondary cracks formed in muddy lamination with smaller fracture toughness.Moreover,the combination relationships between nascent and natural cracks mainly conclude direct penetration and deflection,which is affected by the filling degree and morphology of interface cracks and the relationship of lamination types.These conclusions show that laminar continental shale is conducive to forming complex fracture network,which can provide a theoretical basis for the proposal of indicators and methods for fracability evaluation.
文摘Objective:To characterize mosquito larval habitats and the influence of meteorological factors on their prevalence,and to suggest alternatives for vector control in Makkah Al-Mukarramah.Methods:A mosquito survey was conducted within the 16 municipalities of Makkah Al-Mukarramah,from November 2022 to October 2023.The characteristics of larval habitats used by all reported species as oviposition sites were determined.Seasonal house,container,and breteau indices were used to determine larval abundance.Results:16 Species belonging to five genera[Aedes(3 spp.),Anopheles(3 spp.),Culex(8 spp.),Culiseta(1 sp.),and Lutzia(1 sp.)]were collected.A total of 185608 potential mosquito larval habitats were surveyed.Of these,95853(67.4%)were Aedes,45522(32%)were Culex,718(0.5%)were Anopheles,and 38(0.03%)were other species;154726(83.4%)were water sources for mosquito larvae,and among these sources,7663(5.0%)were positive for larvae,with 45.9%indoors and 54.1%outdoors.Most of the positive larval habitats were recorded in Al-Shawqiya(1093,14.3%),Al-Sharayia(1003,13.1%)and Al-Umrah(984,12.8%).A total of 142131 mosquito larvae and pupae were collected.The majority number of positive residences for all mosquito larvae was observed in January 2023(1658,21.6%).Conclusions:New appropriate alternatives for vector control are proposed,such as mechanical,biological,and environmental control.
文摘The strategy of modeling the control mechanism for generating F0 contour of speech signal is studied in this paper. Based on some dynamic characteristics of vocal cord strain, the complex laryngeal mechanism relative to local F0 regulation is simplified to be a feasible physical model. Furthermore, a model function is deduced as the control mechanism for the generation process of local rise-fall patterns, and two kinds of basic feature patterns result with so called rise-fall commands defined by model parameters. on the logarithmic scale of F0 versus time the local characteristics of an F0 contour are approximated by the sum of these patterns generated by appropriate commands. The experimenial results in analyzing and synthesizing the F0 contours of spoken Chinese utterances indicate that the observed F0 contours can be always approximated well by the model, and a good correlation exists between some model parameters and the transition duration of local F0 rising or falling. The model lays a foundation for Chinese F0 contour synthesis by rule.
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)+1 种基金Innovative Talents Fund of Harbin (No.2009RFQXG211)Fundamental Research Fund of HEU (No. HEUFT08003)
文摘An analytical study was presented on active control of sound transmission into a vibro-acoustic enclosure comprising two flexible plates. Two types of actuators were used, i.e. acoustic actuator and distributed lead zirconate titanate piezoelectric (PZT) actuator instead of point force actuator. Using the modal acoustic transfer impedance-mobility matrices, the excitation and interaction in the coupled sound transmission system can be described with clear physical significance. With the control system designed to globally reduce the sound field, different control system configurations were considered, including the structural actuator on the incident plate, actuator on the receiving plate, acoustic actuator on the cavity, and their combinations. The effectiveness and performance of the control strategy corresponding to each system configuration were compared and discussed. The role and control mechanism of each type of actuator were of particular interest. It was shown that the incident plate actuator is effective in controlling the cavity-dominated modes and the structural modes dominated by the incident plate and receiving plate. Two main control mechanisms are involved in this control configuration, i.e., modal suppressing and modal rearrangement. For control system configuration with only acoustic actuator in the enclosure, the mechanism involved in this arrangement is purely modal suppression. Desirable placements of structural actuators in terms of total potential energy reduction were also discussed.
基金This research is supported by National Natural Science Foundation of China
文摘A complex object is an abstraction and description of a complex entity of the real world. Many applications in such domains as CIMS, CAD and OA define and manipulate a complex object as a single unit. In this paper, a definition of the model of complex objects is given, and the concurrency control mechanism of complex objects in WHYMX object-oriented database system is described.
基金supported by the National Natural Science Foundation of China(No.11572023).
文摘Design and implementation of an effective control mechanism is the key to enable the controlledflight of flapping wing rotor micro aerial vehicles(FWR-MAVs).In order to address this open challenge,in this paper,a triple-wing FWR-MAV with its particular control system is proposed.The corresponding experimental study of the vehicle is conducted.As a result,the triple-wing propulsion system demonstrates advantages in both lift generation and flight stability based on the force measurement.The control torques of the proposed FWR-MAV are generated by a particular slipflow rudder mechanism.The effectiveness of such a design combination has been validated experimentally.A series of flight tests are conducted,including sustained hovering and forward-backward maneuvering.To the best of our knowledge,such a design yields the world's first FWR-MAV capable of sustained controlled flight.
