Five samples of muscovite from mylonites of the earlier Tanlu ductile shear zone on the eastern margin of the Dabie Mountains yield 40Ar/39Ar ages ranging from 178 Ma to 196 Ma. Three of them have reliable plateau age...Five samples of muscovite from mylonites of the earlier Tanlu ductile shear zone on the eastern margin of the Dabie Mountains yield 40Ar/39Ar ages ranging from 178 Ma to 196 Ma. Three of them have reliable plateau ages of 188.7±0.7 Ma, 189.7±0.6 Ma and 192.5±0.7 Ma respectively, which indicates a syn-orogenic, sinistral strike-slip thermal event. This displacement movement derived from the continent-continent collision of the North and South China blocks took place in the Early Jurassic and after uplifting of high-pressure to ultrahigh-pressure slabs to the mid-crust. It is suggested that during the collision the Tanlu fault zone was an intracontinental transform fault caused by differential subduction speeds. The 40Ar/39Ar ages of mylonite whole-rock and muscovite from the later Tanlu ductile shear zone suggest another sinistral strike-slip cooling event at 128 Ma. During this strike-slip faulting, large-scale intrusion and doming uplift occurred in the eastern part of the Dabie orogenic belt. Data of K-feldspar 40Ar/39Ar MDD and apatite fission-track analysis from metamorphic rocks indicate two high-speed cooling events experienced by the Tanlu fault zone, which took place at 90 Ma and 45-58 Ma respectively. They correspond respectively to two phases of extensional activities in the Late Cretaceous and Eogene as well as development of the Qianshan fault-controlled basin to the east of the Tanlu fault zone. The cooling times recorded by K-feldspar and apatite show that the uplifting in the Dabie orogenic belt occured earlier than that on the eastern margin occupied by the Tanlu fault zone. The above phenomena suggest that the uplifting of the Dabie orogenic belt during the Late Cretaceous to Eogene was not controlled by the Tanlu normal faulting, but as a result of the lithospheric delamination.展开更多
An alpha-uniformized Markov chain is defined by the concept of equivalent infinitesimalgenerator for a semi-Markov decision process (SMDP) with both average- and discounted-criteria.According to the relations of their...An alpha-uniformized Markov chain is defined by the concept of equivalent infinitesimalgenerator for a semi-Markov decision process (SMDP) with both average- and discounted-criteria.According to the relations of their performance measures and performance potentials, the optimiza-tion of an SMDP can be realized by simulating the chain. For the critic model of neuro-dynamicprogramming (NDP), a neuro-policy iteration (NPI) algorithm is presented, and the performanceerror bound is shown as there are approximate error and improvement error in each iteration step.The obtained results may be extended to Markov systems, and have much applicability. Finally, anumerical example is provided.展开更多
The microscopic structure change rule in high speed steel (HSS) after an additional cryogenic treatment was studied in this paper. Highly dispersed nano-carbide (η-Fe2 C) separated from tempering martensite was found...The microscopic structure change rule in high speed steel (HSS) after an additional cryogenic treatment was studied in this paper. Highly dispersed nano-carbide (η-Fe2 C) separated from tempering martensite was found distributed on twin planes of marten-site and dislocation places. Retained austenite was found sheared into martensite and nano-carbide separated at the same time. In addition, the tempering martensite was fine-grained. The stated changes of HSS evidently improve the lifespan of HSS cutter and fully show the advantages of nano-structure. The cryogenic treatment of HSS also improves the roughness of HSS cutter (decrease Ra number by about 50%) and greatly increases the wear resistance of HSS cutter. Further experiments on the wear characteristic of HSS cutter supported the findings mentioned above. The stated HSS treatment technology would implement nano-structure of traditional tool steel through phase change. It could be a new method to improve the performance of HSS cutter.展开更多
A single-factor experiment of copper ion adsorption on pure palygorskite was carried out to understand the Cu2+ sorption of palygorskite—an important clay mineral in soil and sedimentary rock. In addition, pH of the ...A single-factor experiment of copper ion adsorption on pure palygorskite was carried out to understand the Cu2+ sorption of palygorskite—an important clay mineral in soil and sedimentary rock. In addition, pH of the solution and the surface microstructure of palygorskite were investigated before and after adsorption. The experimental results indicated that efficiency of Cu2+ removal was related to the oscillation rate of the specimen shaker, sorption time, initial pH value and the amount of adsorbent added. Palygorskite induced Cu2+ hydrolysis and interaction between copper hydroxide colloids and palygorskite surfaces, as observed with transmission electron microscopy (TEM), were the main contributions to palygorskite removal of Cu2+. This mechanism was different from adsorption at the mineral-water interface. It was proposed that surface hydrolysis of palygorskite raised the alkalinity of the palygorskite-water interface and suspension system. Thus, the induced pH of the solution was then high enough for Cu2+ hydrolysis on the mineral surface and in solution.展开更多
The Portevin-Le Chatelier (PLC) effect means serrated yielding or jerky flow phenomenon in some alloys. In this paper a macroscopic model is developed to investigate the PLC effect with the emphasis on mechanical resp...The Portevin-Le Chatelier (PLC) effect means serrated yielding or jerky flow phenomenon in some alloys. In this paper a macroscopic model is developed to investigate the PLC effect with the emphasis on mechanical response of the structure evolution on microscopic scale. In addition to the normal work hardening effect, the model takes account of the thermal activation of dislocation moving with the aid of stress and the collective interactions between mobile dislocations and solute atoms due to dynamic strain ageing (DSA). It can satisfy the negative strain rate sensitivity of flow stress, which is believed to be one of the most special features associated with the PLC effect. The heterogeneous nature of the deformed material is also considered by introducing a nonuniform spatial distribution of some model parameters. The serrated yielding and localized deformation behavior can be successfully reproduced via numerical simulation based on this model.展开更多
A promising approach on the search for geometric constraint of directionalgraph in off-line parametric design has been put forward. The method for representation of thedirectional graph is given firstly, then the cons...A promising approach on the search for geometric constraint of directionalgraph in off-line parametric design has been put forward. The method for representation of thedirectional graph is given firstly, then the constraint model for every geometry element is putforward. By the search of geometric constraint, it sets up the topology constraint relation on thedifferent element objects, which are not related in geometry data base, and achieves the identifyfor the directional graph. The algorithm of recognizing geometric constraint is described in detail,in the meantime, the application example in off-line parametric design on dimension-driven isgiven.展开更多
Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional met...Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional metallogeny is discussed, and the ore-forming fluid systems are classified in this article. It is proposed that the fluid ore-forming activities in the Jiangnan Uplift both in northern Jiangxi and southern Anhui have close relationships with the crust-mantle interaction and magmatic-tectonic activities. The types and scales of the mineralization on the both sides of the eastern Jiangnan Uplift were determined by fluid ore-forming systems and geological backgrounds.展开更多
Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of ...Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.展开更多
Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juic...Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juices were investigated under 20 - 80 MPa, 35 - 58℃, pH 3. 0 - 6. 0 and processing time 0-8 min. Results showed that the loss of Vc increased with elevated processing temperatures(50 MPa, 4 min). When the temperature of raw juices was 35℃, the retention of total Vc was higher under 40 - 60 MPa than that under the pressure < 40 MPa or > 60 MPa, and it was up to 94%(4 min). The retention of total Vc decreases slowly within 6 min, but rapidly after 6 min. The pH can also influence the retention of total Vc, and this retention can come to a highest point at pH 6.0.展开更多
Semiconductor CdS nanoparticles were synthesized by the sonochemical reduction of a mixed aqueous solution of CdCl2, Na2S2O3 and (CH3)CHOH in Ar atmosphere at room temperature. The results of a detailed investigation ...Semiconductor CdS nanoparticles were synthesized by the sonochemical reduction of a mixed aqueous solution of CdCl2, Na2S2O3 and (CH3)CHOH in Ar atmosphere at room temperature. The results of a detailed investigation with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum and optical absorption spec-troscopy are reported. A clearly red shift of the absorption edge and a broad absorption band related to the surface states of nanoparticles have been observed in the optical absorption spectra with the increasing of CdS particle size. The mechanisms of the CdS nanoparticle formation and size growth during sonochemical irradiation were discussed. This convenient method is found to be an efficient way to produce other chalcogenides as well.展开更多
Object-oriented Petri nets (OPNs) is extended into stochastic object-oriented Petri nets (SOPNs) by associating the OPN of an object with stochastic transitions and introducing stochastic places. The stochastic transi...Object-oriented Petri nets (OPNs) is extended into stochastic object-oriented Petri nets (SOPNs) by associating the OPN of an object with stochastic transitions and introducing stochastic places. The stochastic transition of the SOPNs of a production resources can be used to model its reliability, while the SOPN of a production resource can describe its performance with reliability considered. The SOPN model of a case production system is built to illustrate the relationship between the system's performances and the failures of individual production resources.展开更多
The effects of the secondary gradient crystallizing pressure, temperature and time on the purity and crystallization ratio of andrographolide were investigated via single factor experiments. The shape of crystal was...The effects of the secondary gradient crystallizing pressure, temperature and time on the purity and crystallization ratio of andrographolide were investigated via single factor experiments. The shape of crystal was observed with scanning electron microscopy (SEM). The purity of andrographolide was determined by high pressure liquid chromatography (HPLC). It was found that the optimized parameters were pressure 14 MPa, temperature 55℃, time 60 min, and CO2 flow rate 15 L min-1, under these conditions the particle of andrographolide was much smaller, the crystal of andrographolide was distributed in floccule on crystal board,with the purity of andrographolide 92.5%, the crystallization ratio 48.9%.展开更多
Electroless nickel (copper)-phosphorus-silicon carbide (SiC)-polytetrafluoroethylene (PTFE) composite coatings were prepared by adding SiC and PTFE into electroless nickel (copper)-phosphorus alloy baths. The effects ...Electroless nickel (copper)-phosphorus-silicon carbide (SiC)-polytetrafluoroethylene (PTFE) composite coatings were prepared by adding SiC and PTFE into electroless nickel (copper)-phosphorus alloy baths. The effects of addition of SiC and PTFE on depositing rate, microhardness, wear resistance and anti-friction of the resulted composite coatings were studied. The results indicated that electroless nickel (copper)-phosphorus alloy coatings were greatly improved in depositing rate, microhardness, wear resistance and antifriction by co-deposited proper amount of SiC and PTFE.展开更多
A new technique has been developed to prepare woodceramics with the raw material of wheat straws.The partial properties of woodceramics such as the remains of carbon, the density, the porosity, the bending strength, a...A new technique has been developed to prepare woodceramics with the raw material of wheat straws.The partial properties of woodceramics such as the remains of carbon, the density, the porosity, the bending strength, and resistivity are tested at the same time. Systematic analyses of the material properties, the forming mechanism, and the regularity of woodceramics are made. The effects of the formula of raw materials, the consistencies of phenol resin, and the temperature, on the technique and the properties of woodceramics are displayed. It is shown that wheat straws can be used to produce woodceramics with this technique. The presented work provides useful ideas for the study of the preparation of woodceramics.展开更多
A novel fuzzy logic compensating (FLC) scheme is proposed to enhance theconventional computed-torque control (CTC) structure of manipulators The control scheme is based onthe combination of a classical CTC and FLC, an...A novel fuzzy logic compensating (FLC) scheme is proposed to enhance theconventional computed-torque control (CTC) structure of manipulators The control scheme is based onthe combination of a classical CTC and FLC, and the resulting control scheme has a simple structurewith improved robustness. Further improvement of the performance of the FLC scheme is achievedthrough automatic tuning of a weight parameter a leading to a self-tuning fuzzy logic compensator,so the system uncertainty can be compensated very well. By taking into account the full nonlinearnature of the robotic dynamics, the overall closed-loop system is shown to be asymptotically stable.Experimental results demonstrate the effectiveness of the computed torque and fuzzy compensationscheme to control a manipulator during a trajectory tracking task.展开更多
The mixture model of Al_(85)Y_4Nd_4Ni_7 alloy in which a partiallycrystallized amorphous alloy is regarded as a nanocornposite of an Al nanoparticle and a remainingamorphous matrix is presented. Its evolution in the p...The mixture model of Al_(85)Y_4Nd_4Ni_7 alloy in which a partiallycrystallized amorphous alloy is regarded as a nanocornposite of an Al nanoparticle and a remainingamorphous matrix is presented. Its evolution in the process of crystallization has been investigatedby differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electronmicroscopy (TEM). Mainly amorphous structure with alpha-Al nanocrystals embedded in the amorphousmatrix has been revealed by melt spining the alloy. Crystallization is showed to occur in threestages: (1) crystallization of amorphous alloy and formation of AINiY, AINdNi and unknowncrystalline phases, (2) formation of Al_3 Y and Al_3Nd, and (3) formation of Al_3Ni.展开更多
Based on the improved mode superposition method proposed by Z. D. Ma and I.Hagiwara, a precisely compensated efficient mode synthesis method is developed. The calculationprocedure is discussed in detail and the trunca...Based on the improved mode superposition method proposed by Z. D. Ma and I.Hagiwara, a precisely compensated efficient mode synthesis method is developed. The calculationprocedure is discussed in detail and the truncation error is also analyzed. By comparison, it isshown that this method has a higher accuracy and a less calculation time than the general used ones.展开更多
基金The research was supported by the National Natural Science Foundation of China(Grant 40272094).
文摘Five samples of muscovite from mylonites of the earlier Tanlu ductile shear zone on the eastern margin of the Dabie Mountains yield 40Ar/39Ar ages ranging from 178 Ma to 196 Ma. Three of them have reliable plateau ages of 188.7±0.7 Ma, 189.7±0.6 Ma and 192.5±0.7 Ma respectively, which indicates a syn-orogenic, sinistral strike-slip thermal event. This displacement movement derived from the continent-continent collision of the North and South China blocks took place in the Early Jurassic and after uplifting of high-pressure to ultrahigh-pressure slabs to the mid-crust. It is suggested that during the collision the Tanlu fault zone was an intracontinental transform fault caused by differential subduction speeds. The 40Ar/39Ar ages of mylonite whole-rock and muscovite from the later Tanlu ductile shear zone suggest another sinistral strike-slip cooling event at 128 Ma. During this strike-slip faulting, large-scale intrusion and doming uplift occurred in the eastern part of the Dabie orogenic belt. Data of K-feldspar 40Ar/39Ar MDD and apatite fission-track analysis from metamorphic rocks indicate two high-speed cooling events experienced by the Tanlu fault zone, which took place at 90 Ma and 45-58 Ma respectively. They correspond respectively to two phases of extensional activities in the Late Cretaceous and Eogene as well as development of the Qianshan fault-controlled basin to the east of the Tanlu fault zone. The cooling times recorded by K-feldspar and apatite show that the uplifting in the Dabie orogenic belt occured earlier than that on the eastern margin occupied by the Tanlu fault zone. The above phenomena suggest that the uplifting of the Dabie orogenic belt during the Late Cretaceous to Eogene was not controlled by the Tanlu normal faulting, but as a result of the lithospheric delamination.
文摘An alpha-uniformized Markov chain is defined by the concept of equivalent infinitesimalgenerator for a semi-Markov decision process (SMDP) with both average- and discounted-criteria.According to the relations of their performance measures and performance potentials, the optimiza-tion of an SMDP can be realized by simulating the chain. For the critic model of neuro-dynamicprogramming (NDP), a neuro-policy iteration (NPI) algorithm is presented, and the performanceerror bound is shown as there are approximate error and improvement error in each iteration step.The obtained results may be extended to Markov systems, and have much applicability. Finally, anumerical example is provided.
文摘The microscopic structure change rule in high speed steel (HSS) after an additional cryogenic treatment was studied in this paper. Highly dispersed nano-carbide (η-Fe2 C) separated from tempering martensite was found distributed on twin planes of marten-site and dislocation places. Retained austenite was found sheared into martensite and nano-carbide separated at the same time. In addition, the tempering martensite was fine-grained. The stated changes of HSS evidently improve the lifespan of HSS cutter and fully show the advantages of nano-structure. The cryogenic treatment of HSS also improves the roughness of HSS cutter (decrease Ra number by about 50%) and greatly increases the wear resistance of HSS cutter. Further experiments on the wear characteristic of HSS cutter supported the findings mentioned above. The stated HSS treatment technology would implement nano-structure of traditional tool steel through phase change. It could be a new method to improve the performance of HSS cutter.
基金1 Project supported by the National Natural Science Foundation of China (Nos. 40472026 and 40072017).
文摘A single-factor experiment of copper ion adsorption on pure palygorskite was carried out to understand the Cu2+ sorption of palygorskite—an important clay mineral in soil and sedimentary rock. In addition, pH of the solution and the surface microstructure of palygorskite were investigated before and after adsorption. The experimental results indicated that efficiency of Cu2+ removal was related to the oscillation rate of the specimen shaker, sorption time, initial pH value and the amount of adsorbent added. Palygorskite induced Cu2+ hydrolysis and interaction between copper hydroxide colloids and palygorskite surfaces, as observed with transmission electron microscopy (TEM), were the main contributions to palygorskite removal of Cu2+. This mechanism was different from adsorption at the mineral-water interface. It was proposed that surface hydrolysis of palygorskite raised the alkalinity of the palygorskite-water interface and suspension system. Thus, the induced pH of the solution was then high enough for Cu2+ hydrolysis on the mineral surface and in solution.
基金This work was supported by the National Natural Seience Foundation of China under gran No.10372098 and 10232030.We would also like to thank the Lab of Mechanical&Materials Science of USTC for their help in the experiments on MTS
文摘The Portevin-Le Chatelier (PLC) effect means serrated yielding or jerky flow phenomenon in some alloys. In this paper a macroscopic model is developed to investigate the PLC effect with the emphasis on mechanical response of the structure evolution on microscopic scale. In addition to the normal work hardening effect, the model takes account of the thermal activation of dislocation moving with the aid of stress and the collective interactions between mobile dislocations and solute atoms due to dynamic strain ageing (DSA). It can satisfy the negative strain rate sensitivity of flow stress, which is believed to be one of the most special features associated with the PLC effect. The heterogeneous nature of the deformed material is also considered by introducing a nonuniform spatial distribution of some model parameters. The serrated yielding and localized deformation behavior can be successfully reproduced via numerical simulation based on this model.
基金This project is supported by National 863/C1MS Plan(No.863-511-507) Provincial Natural Science Foundation of Anhui, China (No.01042209).
文摘A promising approach on the search for geometric constraint of directionalgraph in off-line parametric design has been put forward. The method for representation of thedirectional graph is given firstly, then the constraint model for every geometry element is putforward. By the search of geometric constraint, it sets up the topology constraint relation on thedifferent element objects, which are not related in geometry data base, and achieves the identifyfor the directional graph. The algorithm of recognizing geometric constraint is described in detail,in the meantime, the application example in off-line parametric design on dimension-driven isgiven.
基金the National NaturalScience Foundation of China(Grant No.40272048)thegeological survey project of the Ministry of Land andResource(Grant No.K1.4-2-2)+1 种基金the Anhui Provincial Exccllent Youth Science and Technology Foundation(04045063) the Anhui Provincial Natural Scicnce Foundation(Grant No.01045202).
文摘Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional metallogeny is discussed, and the ore-forming fluid systems are classified in this article. It is proposed that the fluid ore-forming activities in the Jiangnan Uplift both in northern Jiangxi and southern Anhui have close relationships with the crust-mantle interaction and magmatic-tectonic activities. The types and scales of the mineralization on the both sides of the eastern Jiangnan Uplift were determined by fluid ore-forming systems and geological backgrounds.
文摘Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.
文摘Based on the instantaneous high-pressure(IHP)produced by high-pressure single pole-cylinder pump, the effects of combining this pressure with medium temperature on the retention of total vitamin C(Vc)in wax gourd juices were investigated under 20 - 80 MPa, 35 - 58℃, pH 3. 0 - 6. 0 and processing time 0-8 min. Results showed that the loss of Vc increased with elevated processing temperatures(50 MPa, 4 min). When the temperature of raw juices was 35℃, the retention of total Vc was higher under 40 - 60 MPa than that under the pressure < 40 MPa or > 60 MPa, and it was up to 94%(4 min). The retention of total Vc decreases slowly within 6 min, but rapidly after 6 min. The pH can also influence the retention of total Vc, and this retention can come to a highest point at pH 6.0.
基金This work was supported by the National Key Basic Research Project(G1999064501)the Natural Science Foundation of Anhui Province(No.01044903).
文摘Semiconductor CdS nanoparticles were synthesized by the sonochemical reduction of a mixed aqueous solution of CdCl2, Na2S2O3 and (CH3)CHOH in Ar atmosphere at room temperature. The results of a detailed investigation with X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectrum and optical absorption spec-troscopy are reported. A clearly red shift of the absorption edge and a broad absorption band related to the surface states of nanoparticles have been observed in the optical absorption spectra with the increasing of CdS particle size. The mechanisms of the CdS nanoparticle formation and size growth during sonochemical irradiation were discussed. This convenient method is found to be an efficient way to produce other chalcogenides as well.
基金This project is supported by National Natural Science Foundation of China (No.50085003).
文摘Object-oriented Petri nets (OPNs) is extended into stochastic object-oriented Petri nets (SOPNs) by associating the OPN of an object with stochastic transitions and introducing stochastic places. The stochastic transition of the SOPNs of a production resources can be used to model its reliability, while the SOPN of a production resource can describe its performance with reliability considered. The SOPN model of a case production system is built to illustrate the relationship between the system's performances and the failures of individual production resources.
基金financially supported by the National Natura1 Science Foundation of China(29976008)
文摘The effects of the secondary gradient crystallizing pressure, temperature and time on the purity and crystallization ratio of andrographolide were investigated via single factor experiments. The shape of crystal was observed with scanning electron microscopy (SEM). The purity of andrographolide was determined by high pressure liquid chromatography (HPLC). It was found that the optimized parameters were pressure 14 MPa, temperature 55℃, time 60 min, and CO2 flow rate 15 L min-1, under these conditions the particle of andrographolide was much smaller, the crystal of andrographolide was distributed in floccule on crystal board,with the purity of andrographolide 92.5%, the crystallization ratio 48.9%.
文摘Electroless nickel (copper)-phosphorus-silicon carbide (SiC)-polytetrafluoroethylene (PTFE) composite coatings were prepared by adding SiC and PTFE into electroless nickel (copper)-phosphorus alloy baths. The effects of addition of SiC and PTFE on depositing rate, microhardness, wear resistance and anti-friction of the resulted composite coatings were studied. The results indicated that electroless nickel (copper)-phosphorus alloy coatings were greatly improved in depositing rate, microhardness, wear resistance and antifriction by co-deposited proper amount of SiC and PTFE.
基金Supported by the item of innovating group of Hefei university of technology.
文摘A new technique has been developed to prepare woodceramics with the raw material of wheat straws.The partial properties of woodceramics such as the remains of carbon, the density, the porosity, the bending strength, and resistivity are tested at the same time. Systematic analyses of the material properties, the forming mechanism, and the regularity of woodceramics are made. The effects of the formula of raw materials, the consistencies of phenol resin, and the temperature, on the technique and the properties of woodceramics are displayed. It is shown that wheat straws can be used to produce woodceramics with this technique. The presented work provides useful ideas for the study of the preparation of woodceramics.
文摘A novel fuzzy logic compensating (FLC) scheme is proposed to enhance theconventional computed-torque control (CTC) structure of manipulators The control scheme is based onthe combination of a classical CTC and FLC, and the resulting control scheme has a simple structurewith improved robustness. Further improvement of the performance of the FLC scheme is achievedthrough automatic tuning of a weight parameter a leading to a self-tuning fuzzy logic compensator,so the system uncertainty can be compensated very well. By taking into account the full nonlinearnature of the robotic dynamics, the overall closed-loop system is shown to be asymptotically stable.Experimental results demonstrate the effectiveness of the computed torque and fuzzy compensationscheme to control a manipulator during a trajectory tracking task.
文摘The mixture model of Al_(85)Y_4Nd_4Ni_7 alloy in which a partiallycrystallized amorphous alloy is regarded as a nanocornposite of an Al nanoparticle and a remainingamorphous matrix is presented. Its evolution in the process of crystallization has been investigatedby differential scanning calorimetry (DSC), X-ray diffraction (XRD), and transmission electronmicroscopy (TEM). Mainly amorphous structure with alpha-Al nanocrystals embedded in the amorphousmatrix has been revealed by melt spining the alloy. Crystallization is showed to occur in threestages: (1) crystallization of amorphous alloy and formation of AINiY, AINdNi and unknowncrystalline phases, (2) formation of Al_3 Y and Al_3Nd, and (3) formation of Al_3Ni.
文摘Based on the improved mode superposition method proposed by Z. D. Ma and I.Hagiwara, a precisely compensated efficient mode synthesis method is developed. The calculationprocedure is discussed in detail and the truncation error is also analyzed. By comparison, it isshown that this method has a higher accuracy and a less calculation time than the general used ones.
