In this paper, a successfully studied and developed master - slave muld - microcomputers control system based on PC - BUS for hollow spindle fancy yarn spinning machine, mainly Its overall scheme, software and hardwar...In this paper, a successfully studied and developed master - slave muld - microcomputers control system based on PC - BUS for hollow spindle fancy yarn spinning machine, mainly Its overall scheme, software and hardware construction, is introduced. Spinning experiments show that the system achieves satisfactory result. This system can solve the diftkultles of mechatronical fusion between domestic hollow splndk fancy yarn spuming muchine and its microcomputer control technology.展开更多
CD47 is a ubiquitous and pleiotropic cell-surface receptor.Disrupting CD47 enhances injury repair in various tissues but the role of CD47 has not been studied in bone injuries.In a murine closed-fracture model,CD47-nu...CD47 is a ubiquitous and pleiotropic cell-surface receptor.Disrupting CD47 enhances injury repair in various tissues but the role of CD47 has not been studied in bone injuries.In a murine closed-fracture model,CD47-null mice showed decreased callus bone formation as assessed by microcomputed tomography 10 days post-fracture and increased fibrous volume as determined by histology.To understand the cellular basis for this phenotype,mesenchymal progenitors(MSC)were harvested from bone marrow.CD47-null MSC showed decreased large fibroblast colony formation(CFU-F),significantly less proliferation,and fewer cells in Sphase,although osteoblast differentiation was unaffected.However,consistent with prior research,CD47-null endothelial cells showed increased proliferation relative to WT cells.Similarly,in a murine ischemic fracture model,CD47-null mice showed reduced fracture callus size due to a reduction in bone relative to WT 15 days-post fracture.Consistent with our in vitro results,in vivo EdU labeling showed decreased cell proliferation in the callus of CD47-null mice,while staining for CD31 and endomucin demonstrated increased endothelial cell density.Finally,WT mice with ischemic fracture that were administered a CD47 morpholino,which blocks CD47 protein production,showed a callus phenotype similar to that of ischemic fractures in CD47-null mice,suggesting the phenotype was not due to developmental changes in the knockout mice.Thus,inhibition of CD47 during bone healing reduces both non-ischemic and ischemic fracture healing,in part,by decreasing MSC proliferation.Furthermore,the increase in endothelial cell proliferation and early blood vessel density caused by CD47 disruption is not sufficient to overcome MSC dysfunction.展开更多
Deep geological sequestration is widely recognized as a reliable method for nuclear waste management,with expanded applications in thermal energy storage and adiabatic compressed air energy storage systems.This study ...Deep geological sequestration is widely recognized as a reliable method for nuclear waste management,with expanded applications in thermal energy storage and adiabatic compressed air energy storage systems.This study evaluated the suitability of granite,basalt,and marble as reservoir rocks capable of withstanding extreme high-temperature and high-pressure conditions.Using a custom-designed triaxial testing apparatus for thermal-hydro-mechanical(THM)coupling,we subjected rock samples to temperatures ranging from 20℃to 800℃,triaxial stresses up to 25 MPa,and seepage pressures of 0.6 MPa.After THM treatment,the specimens were analyzed using a Real-Time Load-Synchronized Micro-Computed Tomography(MCT)Scanner under a triaxial stress of 25 MPa,allowing for high-resolution insights into pore and fissure responses.Our findings revealed distinct thermal stability profiles and microscopic parameter changes across three phasesdslow growth,slow decline,and rapid growthdwith critical temperature thresholds observed at 500℃for granite,600℃for basalt,and 300℃for marble.Basalt showed minimal porosity changes,increasing gradually from 3.83%at 20℃to 12.45%at 800℃,indicating high structural integrity and resilience under extreme THM conditions.Granite shows significant increases in porosity due to thermally induced microcracking,while marble rapidly deteriorated beyond 300℃due to carbonate decomposition.Consequently,basalt,with its minimal porosity variability,high thermal stability,and robust mechanical properties,emerges as an optimal candidate for nuclear waste repositories and other high-temperature geological engineering applications,offering enhanced reliability,structural stability,and long-term safety in such settings.展开更多
Exo-atmospheric vehicles are constrained by limited maneuverability,which leads to the contradiction between evasive maneuver and precision strike.To address the problem of Integrated Evasion and Impact(IEI)decision u...Exo-atmospheric vehicles are constrained by limited maneuverability,which leads to the contradiction between evasive maneuver and precision strike.To address the problem of Integrated Evasion and Impact(IEI)decision under multi-constraint conditions,a hierarchical intelligent decision-making method based on Deep Reinforcement Learning(DRL)was proposed.First,an intelligent decision-making framework of“DRL evasion decision”+“impact prediction guidance decision”was established:it takes the impact point deviation correction ability as the constraint and the maximum miss distance as the objective,and effectively solves the problem of poor decisionmaking effect caused by the large IEI decision space.Second,to solve the sparse reward problem faced by evasion decision-making,a hierarchical decision-making method consisting of maneuver timing decision and maneuver duration decision was proposed,and the corresponding Markov Decision Process(MDP)was designed.A detailed simulation experiment was designed to analyze the advantages and computational complexity of the proposed method.Simulation results show that the proposed model has good performance and low computational resource requirement.The minimum miss distance is 21.3 m under the condition of guaranteeing the impact point accuracy,and the single decision-making time is 4.086 ms on an STM32F407 single-chip microcomputer,which has engineering application value.展开更多
Oral and maxillofacial diagnostic imaging is of paramount importance in dental clinical diagnosis,treatment planning,and follow-up procedures.Periapical ra-diographic examination and numerous panoramic systems are use...Oral and maxillofacial diagnostic imaging is of paramount importance in dental clinical diagnosis,treatment planning,and follow-up procedures.Periapical ra-diographic examination and numerous panoramic systems are used in routine clinical dental practice.Cone beam CT is widely used and currently the method of choice in oral and maxillofacial implantology,endodontics,maxillofacial surgery,periodontics,degenerative temporomandibular joint disease,orthodontics,airway studies,sleep disorders,and forensic dentistry.Another innovative laboratory re-search tool that offers three-dimensional(3D)detailed high-resolution images of in vitro teeth and neighboring structures with submicrometric accuracy is micro-computed tomography.Ultra-high radiation doses,long scanning times,and high costs preclude its routine clinical use.In response to the high demand for a te-chnique that could provide real-time images using a cost-effective,rapid,user-friendly,and portable technique without ionizing radiation,some authors pro-posed ultrasound imaging methods as an alternative to X-ray imaging techniques.Ultrasonography can be used in the dentomaxillofacial region for various diagno-stic purposes such as salivary gland and superficial tissue examination.Recently,dedicated dental magnetic resonance imaging with appropriate software,hard-ware,sequences,and field of view tailored to fit dentomaxillofacial anatomy was introduced.Lately,3D printing technologies and their application in dentistry has attracted attention.During 3D printing a given material is added in successive layers to create a 3D object.The application of this technology has the potential to decrease operation time and minimize operator bias and the possibility of proce-dural errors.Another hot topic regarding dentomaxillofacial radiology is artificial intelligence,which is a field related to computer science dedicated to developing systems or machines that can perform tasks traditionally associated with human intelligence.It is obvious that further investigation and research in the field of dentomaxillofacial radiology will make great contributions to diagnostic imaging for various dental specialties.展开更多
Using photonic crystals (PCs), the extraction efficiency of the light-emitting diodes (LEDs) can be greatly enhanced by the effects of photonic band gap (PBG) and grating diffraction. The two theoretical methods are a...Using photonic crystals (PCs), the extraction efficiency of the light-emitting diodes (LEDs) can be greatly enhanced by the effects of photonic band gap (PBG) and grating diffraction. The two theoretical methods are also discussed. Meanwhile, we demonstrate that LEDs can achieve high extraction efficiency by employing photonic crystal as diffraction grating. PCs with square lattice of cylindrical unit cells are fabricated in GaN layer of GaN-based blue LED. We present a theoretical discussion on the extraction efficiency of PC-LED, which relies on the effective medium theory and transmission matrix method to investigate the effect of lattice constant. The results show that the extraction efficiency of the high performance LEDs can achieve 61.8% when the lattice constant is 270 nm.展开更多
A DC regulated power supply with numerical control based on single chip microcomputer （SCM） is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage ca...A DC regulated power supply with numerical control based on single chip microcomputer （SCM） is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage can be obtained through D/A converter （DAC0832） so that different voltages can be provided by operational amplifier. The output voltage varies from 0 V to 12 V with the incremental value of 0. 1 V. The actual output voltage is shown in the nixietube. This DC regulated power supply is characterized by simple structure and easy operation.展开更多
Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and softwar...Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and software programming were completed,and a relevantexperimental system was PUT forward to test the newly designed controller.Result The experi-mental study showed that the newlydesigned controller had good speed-adjusting characteristicfor a switched reluctance motor ,its stable error was less than 5% and its full-load startingtime was shorter than 1.8s .Conclusion The new controller has reasonable circuit design and suitable controlling algorithm,and it is a feasible SRD system controller design scheme.展开更多
With principles of reliability, independence, practicality and economical effi- ciency, a set of intelligent fire alarm system based on AVRmega128 single chip microcomputer was designed to solve problems of fire alarm...With principles of reliability, independence, practicality and economical effi- ciency, a set of intelligent fire alarm system based on AVRmega128 single chip microcomputer was designed to solve problems of fire alarm system in many large- scale warehouses. Using advanced flame sensor, 485 bus communication, computer interactive software and related peripheral devices, this intelligent fire alarm system has functions of sound-light alarm and intelligent fire extinguishing. The human-com- puter interactive software was adopted for the remote control of the alarm main control panel through the 485 bus communication. This design of intelligent fire alarm system shows high reference and practical value to the development of intel- ligent alarm products with high integration and high reliability.展开更多
Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SE...Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SEM)are employed to visualize and quantify morphological evolution characteristics of fractures in coal after LN2 thermal shocking treatments.LN2 thermal shocking leads to a denser fracture network than its original state with coal porosity growth rate increasing up to 183.3%.The surface porosity of theμCT scanned layers inside the coal specimen is influenced by LN2 thermal shocking which rises from 18.76%to 215.11%,illustrating the deformation heterogeneity of coal after LN2 thermal shocking.The cracking effect of LN2 thermal shocking on the surface of low porosity is generally more effective than that of high surface porosity,indicating the applicability of LN2 thermal shocking on low-permeability CBM reservoir stimulation.The characteristics of SEM scanned coal matrix in the coal powder and the coal block after the LN2 thermal shocking presented a large amount of deep and shallow progressive scratch layers,fracture variation diversity(i.e.extension,propagation,connectivity,irregularity)on the surface of the coal block and these were the main reasons leading to the decrease of the uniaxial compressive strength of the coal specimen.展开更多
Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to ...Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.展开更多
This study investigated the formulation mechanism of microspheres via internal surfactant distribution. Eudragit L100 based microspheres loaded with bovine serum albumin were prepared by solid in oil in oil emulsion s...This study investigated the formulation mechanism of microspheres via internal surfactant distribution. Eudragit L100 based microspheres loaded with bovine serum albumin were prepared by solid in oil in oil emulsion solvent evaporation method using acetone and liquid paraffin system containing sucrose stearate as a surfactant. The fabricated microspheres were evaluated for encapsulation efficiency, particle size, production yield, and in vitro release characteristics. The internal structures of microspheres were characterized using synchrotron radiation X-ray microcomputed tomography(SR-μCT). The enhanced contrast made the sucrose stearate distinguished from Eudragit to have its three dimensional(3D) distribution. Results indicated that the content and concentration determined the state of sucrose stearate and had significant influences on the release kinetics of protein. The dispersity of sucrose stearate was the primary factor that controlled the structure of the microspheres and further affected the encapsulation efficiency, effective drug loading, as well as in vitro release behavior. In conclusion, the 3D internal distribution of surfactant in microspheres and its effects on protein release behaviors have been revealed for the first time. The highly resolved 3D architecture provides new evidence for the deep understanding of the microsphere formation mechanism.展开更多
Through analyzing the principle of spindle drive of winding mechanism for high speed spinning machine,the article not only describes a kind of mode of spindle drive for take-up motion on the basis of control method of...Through analyzing the principle of spindle drive of winding mechanism for high speed spinning machine,the article not only describes a kind of mode of spindle drive for take-up motion on the basis of control method of constant velocity winding, but also introduces the design technique of software and hardware for the control system of mechatronics of spindle drive mode for take- up motion on the basis of constant velocity winding for high speed spinning machine with single-chip microcomputer. The mathematical model to describe the spindle rotating speed is established. It is an important technology for high speed spinning machine and provides a feasible application way.展开更多
A microcomputer control system based on 80C320 and a switching regulation of wire feeder were designed. A correction factor based double model fuzzy logic controller （FLC） was introduced to achieve welding digital a...A microcomputer control system based on 80C320 and a switching regulation of wire feeder were designed. A correction factor based double model fuzzy logic controller （FLC） was introduced to achieve welding digital and intellectualized control by means of wire feeding speed feedback. The controller has many functions such as keyboard input, light emitting diode （LED） display and real-time intellectualized control of welding process etc. The controlling performance influenced by the coefficient of correction function was discussed. It was concluded by the experiments the relation between the coefficient of correction function and welding quality, when the coefficient of correction function is great, the dynamic character of controller is better, when the coefficient of correction function is small, the sensitivity character of controller is better. Experimental results also show that digital and fuzzy logic control method enable the improvement of appearance of weld and stability of welding process to be achieved in submerged arc automatic welding.展开更多
文摘In this paper, a successfully studied and developed master - slave muld - microcomputers control system based on PC - BUS for hollow spindle fancy yarn spinning machine, mainly Its overall scheme, software and hardware construction, is introduced. Spinning experiments show that the system achieves satisfactory result. This system can solve the diftkultles of mechatronical fusion between domestic hollow splndk fancy yarn spuming muchine and its microcomputer control technology.
基金supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases(NIAMS)of the National Institutes of Health(NIH)under award numbers F30AR071201(R.L.Z.)and R01 AR066028(K.D.H.)Additional research support is provided by the NIH under a training award T32TR004371(C.A.C.).
文摘CD47 is a ubiquitous and pleiotropic cell-surface receptor.Disrupting CD47 enhances injury repair in various tissues but the role of CD47 has not been studied in bone injuries.In a murine closed-fracture model,CD47-null mice showed decreased callus bone formation as assessed by microcomputed tomography 10 days post-fracture and increased fibrous volume as determined by histology.To understand the cellular basis for this phenotype,mesenchymal progenitors(MSC)were harvested from bone marrow.CD47-null MSC showed decreased large fibroblast colony formation(CFU-F),significantly less proliferation,and fewer cells in Sphase,although osteoblast differentiation was unaffected.However,consistent with prior research,CD47-null endothelial cells showed increased proliferation relative to WT cells.Similarly,in a murine ischemic fracture model,CD47-null mice showed reduced fracture callus size due to a reduction in bone relative to WT 15 days-post fracture.Consistent with our in vitro results,in vivo EdU labeling showed decreased cell proliferation in the callus of CD47-null mice,while staining for CD31 and endomucin demonstrated increased endothelial cell density.Finally,WT mice with ischemic fracture that were administered a CD47 morpholino,which blocks CD47 protein production,showed a callus phenotype similar to that of ischemic fractures in CD47-null mice,suggesting the phenotype was not due to developmental changes in the knockout mice.Thus,inhibition of CD47 during bone healing reduces both non-ischemic and ischemic fracture healing,in part,by decreasing MSC proliferation.Furthermore,the increase in endothelial cell proliferation and early blood vessel density caused by CD47 disruption is not sufficient to overcome MSC dysfunction.
基金financial supported by Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines(Grant No.DM2022B03)Youth Program of National Natural Science Foundation of China(Grant No.51904195)Scientific and Technological Innovation Programs of Higher Educations Institutions in Shanxi Province(Grant No.2022L608).
文摘Deep geological sequestration is widely recognized as a reliable method for nuclear waste management,with expanded applications in thermal energy storage and adiabatic compressed air energy storage systems.This study evaluated the suitability of granite,basalt,and marble as reservoir rocks capable of withstanding extreme high-temperature and high-pressure conditions.Using a custom-designed triaxial testing apparatus for thermal-hydro-mechanical(THM)coupling,we subjected rock samples to temperatures ranging from 20℃to 800℃,triaxial stresses up to 25 MPa,and seepage pressures of 0.6 MPa.After THM treatment,the specimens were analyzed using a Real-Time Load-Synchronized Micro-Computed Tomography(MCT)Scanner under a triaxial stress of 25 MPa,allowing for high-resolution insights into pore and fissure responses.Our findings revealed distinct thermal stability profiles and microscopic parameter changes across three phasesdslow growth,slow decline,and rapid growthdwith critical temperature thresholds observed at 500℃for granite,600℃for basalt,and 300℃for marble.Basalt showed minimal porosity changes,increasing gradually from 3.83%at 20℃to 12.45%at 800℃,indicating high structural integrity and resilience under extreme THM conditions.Granite shows significant increases in porosity due to thermally induced microcracking,while marble rapidly deteriorated beyond 300℃due to carbonate decomposition.Consequently,basalt,with its minimal porosity variability,high thermal stability,and robust mechanical properties,emerges as an optimal candidate for nuclear waste repositories and other high-temperature geological engineering applications,offering enhanced reliability,structural stability,and long-term safety in such settings.
基金co-supported by the National Natural Science Foundation of China(No.62103432)the China Postdoctoral Science Foundation(No.284881)the Young Talent fund of University Association for Science and Technology in Shaanxi,China(No.20210108)。
文摘Exo-atmospheric vehicles are constrained by limited maneuverability,which leads to the contradiction between evasive maneuver and precision strike.To address the problem of Integrated Evasion and Impact(IEI)decision under multi-constraint conditions,a hierarchical intelligent decision-making method based on Deep Reinforcement Learning(DRL)was proposed.First,an intelligent decision-making framework of“DRL evasion decision”+“impact prediction guidance decision”was established:it takes the impact point deviation correction ability as the constraint and the maximum miss distance as the objective,and effectively solves the problem of poor decisionmaking effect caused by the large IEI decision space.Second,to solve the sparse reward problem faced by evasion decision-making,a hierarchical decision-making method consisting of maneuver timing decision and maneuver duration decision was proposed,and the corresponding Markov Decision Process(MDP)was designed.A detailed simulation experiment was designed to analyze the advantages and computational complexity of the proposed method.Simulation results show that the proposed model has good performance and low computational resource requirement.The minimum miss distance is 21.3 m under the condition of guaranteeing the impact point accuracy,and the single decision-making time is 4.086 ms on an STM32F407 single-chip microcomputer,which has engineering application value.
文摘Oral and maxillofacial diagnostic imaging is of paramount importance in dental clinical diagnosis,treatment planning,and follow-up procedures.Periapical ra-diographic examination and numerous panoramic systems are used in routine clinical dental practice.Cone beam CT is widely used and currently the method of choice in oral and maxillofacial implantology,endodontics,maxillofacial surgery,periodontics,degenerative temporomandibular joint disease,orthodontics,airway studies,sleep disorders,and forensic dentistry.Another innovative laboratory re-search tool that offers three-dimensional(3D)detailed high-resolution images of in vitro teeth and neighboring structures with submicrometric accuracy is micro-computed tomography.Ultra-high radiation doses,long scanning times,and high costs preclude its routine clinical use.In response to the high demand for a te-chnique that could provide real-time images using a cost-effective,rapid,user-friendly,and portable technique without ionizing radiation,some authors pro-posed ultrasound imaging methods as an alternative to X-ray imaging techniques.Ultrasonography can be used in the dentomaxillofacial region for various diagno-stic purposes such as salivary gland and superficial tissue examination.Recently,dedicated dental magnetic resonance imaging with appropriate software,hard-ware,sequences,and field of view tailored to fit dentomaxillofacial anatomy was introduced.Lately,3D printing technologies and their application in dentistry has attracted attention.During 3D printing a given material is added in successive layers to create a 3D object.The application of this technology has the potential to decrease operation time and minimize operator bias and the possibility of proce-dural errors.Another hot topic regarding dentomaxillofacial radiology is artificial intelligence,which is a field related to computer science dedicated to developing systems or machines that can perform tasks traditionally associated with human intelligence.It is obvious that further investigation and research in the field of dentomaxillofacial radiology will make great contributions to diagnostic imaging for various dental specialties.
基金supported by the National Natural Science Foundation of China (No.60877047)the Natural Science Foundation of Hebei Province (No.2010002002)
文摘Using photonic crystals (PCs), the extraction efficiency of the light-emitting diodes (LEDs) can be greatly enhanced by the effects of photonic band gap (PBG) and grating diffraction. The two theoretical methods are also discussed. Meanwhile, we demonstrate that LEDs can achieve high extraction efficiency by employing photonic crystal as diffraction grating. PCs with square lattice of cylindrical unit cells are fabricated in GaN layer of GaN-based blue LED. We present a theoretical discussion on the extraction efficiency of PC-LED, which relies on the effective medium theory and transmission matrix method to investigate the effect of lattice constant. The results show that the extraction efficiency of the high performance LEDs can achieve 61.8% when the lattice constant is 270 nm.
文摘A DC regulated power supply with numerical control based on single chip microcomputer （SCM） is designed. SCM is the main controller and output voltage o{ DC power supply can be set by keyboard. The analog voltage can be obtained through D/A converter （DAC0832） so that different voltages can be provided by operational amplifier. The output voltage varies from 0 V to 12 V with the incremental value of 0. 1 V. The actual output voltage is shown in the nixietube. This DC regulated power supply is characterized by simple structure and easy operation.
文摘Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and software programming were completed,and a relevantexperimental system was PUT forward to test the newly designed controller.Result The experi-mental study showed that the newlydesigned controller had good speed-adjusting characteristicfor a switched reluctance motor ,its stable error was less than 5% and its full-load startingtime was shorter than 1.8s .Conclusion The new controller has reasonable circuit design and suitable controlling algorithm,and it is a feasible SRD system controller design scheme.
基金Supported by the National Natural Science Foundation of China(11275164)~~
文摘With principles of reliability, independence, practicality and economical effi- ciency, a set of intelligent fire alarm system based on AVRmega128 single chip microcomputer was designed to solve problems of fire alarm system in many large- scale warehouses. Using advanced flame sensor, 485 bus communication, computer interactive software and related peripheral devices, this intelligent fire alarm system has functions of sound-light alarm and intelligent fire extinguishing. The human-com- puter interactive software was adopted for the remote control of the alarm main control panel through the 485 bus communication. This design of intelligent fire alarm system shows high reference and practical value to the development of intel- ligent alarm products with high integration and high reliability.
基金Project(2017XKQY012)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Thermal shocking effect occurs when the coalbed methane(CBM)reservoirs meet liquid nitrogen(LN2)of extremely low temperature.In this study,3D via X-ray microcomputer tomography(μCT)and scanning electron microscope(SEM)are employed to visualize and quantify morphological evolution characteristics of fractures in coal after LN2 thermal shocking treatments.LN2 thermal shocking leads to a denser fracture network than its original state with coal porosity growth rate increasing up to 183.3%.The surface porosity of theμCT scanned layers inside the coal specimen is influenced by LN2 thermal shocking which rises from 18.76%to 215.11%,illustrating the deformation heterogeneity of coal after LN2 thermal shocking.The cracking effect of LN2 thermal shocking on the surface of low porosity is generally more effective than that of high surface porosity,indicating the applicability of LN2 thermal shocking on low-permeability CBM reservoir stimulation.The characteristics of SEM scanned coal matrix in the coal powder and the coal block after the LN2 thermal shocking presented a large amount of deep and shallow progressive scratch layers,fracture variation diversity(i.e.extension,propagation,connectivity,irregularity)on the surface of the coal block and these were the main reasons leading to the decrease of the uniaxial compressive strength of the coal specimen.
基金The Project Supported by Doctoral Programme Foundation of Institution of Higher Education
文摘Pump controlled motor electrohydraulic servo systems are much used in circumstances where high power drive is needed. This kind of system has the advantage of energy-saving. But, it also has some defects that have to be improved. Microcomputer control of a pump controlled motor electrohydraulic servo system is studied. A PID controller is first adopted on the closed loop control system, and experimental results are obtained. Then, a model reference adaptive controller is designed and realised on the same system applying a single board microcomputer. Experimental results show that the dynamic properties of the adaptive control system is much better than those of the PID system under different inertia load conditions.
基金the financial support from the National Natural Science Foundation of China(No.81430087)the National Science and Technology Major Project(2013ZX09402103)
文摘This study investigated the formulation mechanism of microspheres via internal surfactant distribution. Eudragit L100 based microspheres loaded with bovine serum albumin were prepared by solid in oil in oil emulsion solvent evaporation method using acetone and liquid paraffin system containing sucrose stearate as a surfactant. The fabricated microspheres were evaluated for encapsulation efficiency, particle size, production yield, and in vitro release characteristics. The internal structures of microspheres were characterized using synchrotron radiation X-ray microcomputed tomography(SR-μCT). The enhanced contrast made the sucrose stearate distinguished from Eudragit to have its three dimensional(3D) distribution. Results indicated that the content and concentration determined the state of sucrose stearate and had significant influences on the release kinetics of protein. The dispersity of sucrose stearate was the primary factor that controlled the structure of the microspheres and further affected the encapsulation efficiency, effective drug loading, as well as in vitro release behavior. In conclusion, the 3D internal distribution of surfactant in microspheres and its effects on protein release behaviors have been revealed for the first time. The highly resolved 3D architecture provides new evidence for the deep understanding of the microsphere formation mechanism.
文摘Through analyzing the principle of spindle drive of winding mechanism for high speed spinning machine,the article not only describes a kind of mode of spindle drive for take-up motion on the basis of control method of constant velocity winding, but also introduces the design technique of software and hardware for the control system of mechatronics of spindle drive mode for take- up motion on the basis of constant velocity winding for high speed spinning machine with single-chip microcomputer. The mathematical model to describe the spindle rotating speed is established. It is an important technology for high speed spinning machine and provides a feasible application way.
基金the National Natural Science Foundation of China under Grant no50575074
文摘A microcomputer control system based on 80C320 and a switching regulation of wire feeder were designed. A correction factor based double model fuzzy logic controller （FLC） was introduced to achieve welding digital and intellectualized control by means of wire feeding speed feedback. The controller has many functions such as keyboard input, light emitting diode （LED） display and real-time intellectualized control of welding process etc. The controlling performance influenced by the coefficient of correction function was discussed. It was concluded by the experiments the relation between the coefficient of correction function and welding quality, when the coefficient of correction function is great, the dynamic character of controller is better, when the coefficient of correction function is small, the sensitivity character of controller is better. Experimental results also show that digital and fuzzy logic control method enable the improvement of appearance of weld and stability of welding process to be achieved in submerged arc automatic welding.
