According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-st...According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-stands can be identified from the distribution of coral reef ages： 7300 - 6000 cal.aBP, 4800 - 4700 cal.aBP, 4300 - 4200 cal.aBP and 3100 - 2900 cal.aBP. The highest sea level occurred around 7300 - 6700 cal.aBP, and biological-morphological zones took their shape during the stage. The later coral reefs developed in ponds, depressions, and developed outwards on both sides of Luhuitou peninsula. The modern coral reefs are developing in out reef flat and reef-front slope. Moreover, the time of high sea levels in the northern South China Sea recorded by coral reefs in the Luhuitou peninsula can link up with that in other parts of South China Sea. That means the high sea levels in the South China Sea during the Holocene, which are relative to the warming climate, have the global background.展开更多
A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of th...A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of the system is discussed,and a system calibration method employing a reference ball is proposed.The geometric model involving four frames is established to calculate the data points based on the reading of the laser probe and position information from the CMM.A measuring experiment for gesso free form surface using this system is carried out.展开更多
The dynamic contact resistances of HH52P electromagnetic relays are measured under different ambient air tem- perature. Their diagnostic parameters are extracted and determined. It is found that the ambient air temper...The dynamic contact resistances of HH52P electromagnetic relays are measured under different ambient air tem- perature. Their diagnostic parameters are extracted and determined. It is found that the ambient air temperature obviously influ- ences some parameters. In order to research its influence on the electrical contact reliability of electromagnetic relay, the statistic analysis is applied to study the static contact resistance, the max of the dynamic contact resistance and the bounce time. It is found that the ambient air temperature regularly influences the three parameters. Thoroughly, the phenomenon is studied and analyzed in the point of material science so as to probe into the essential matter of it.展开更多
Kinematics and dynamics analyses were performed for a spatial 3-revolute joint-revolute joint-clylindric pair(3-RRC) parallel manipulator.This 3-RRC parallel manipulator is composed of a moving platform,a base platfor...Kinematics and dynamics analyses were performed for a spatial 3-revolute joint-revolute joint-clylindric pair(3-RRC) parallel manipulator.This 3-RRC parallel manipulator is composed of a moving platform,a base platform,and three revolute joint-revolute joint-column pair chains which connect the moving platform and the base platform.Firstly,kinematics analysis for 3-RRC parallel manipulator was conducted.Next,on the basis of Lagrange formula,a simply-structured dynamic model of 3-RRC parallel manipulator was derived.Finally,through a calculation example,the variation of motorial parameters of this 3-RRC parallel manipulator,equivalent moment of inertia,driving force/torque and energy consumption was discussed.The research findings have important significance for research and engineering projects such as analyzing dynamic features,mechanism optimization design and control of 3-RRC parallel manipulator.展开更多
A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the i...A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the inner and outer surfaces. Since the maximum length of the workpiece can reach 2 000 mm , it is difficult to be clamped and adjusted and easy to produce clamping error. The eccentricity can be up to 1.5 mm, which has an interaction effect with the probe mounting offset. We mainly study the probe offset of the measuring machine and the influence of the workpiece clamping error on the measurement. A method of controlling the offset of the measuring probe is proposed. The effect of the clamping error is eliminated through the space coordinate transformation of the workpiece axis, and the axis is fitted by the least square method. Finally, a common fixture can be realized to meet the clamping requirements of the workpiece.展开更多
It is due to the need to ensure the security and integrity of equipment, that the non-destructive tests have been increasingly used in the industrial sector. Among these, the ultrasonic pulse echo technique is the mos...It is due to the need to ensure the security and integrity of equipment, that the non-destructive tests have been increasingly used in the industrial sector. Among these, the ultrasonic pulse echo technique is the most used in industry, mainly for its simplicity and efficiency. With one transducer only, it is possible to emit the ultrasonic and receive the echo pulse. The ANNs （artificial neural networks） are artificial intelligence techniques that, when properly trained, align themselves to inspection tests becoming a powerful tool in the detection and fault identification. In this work, the echo pulse technique was used to detect discontinuities in welds, where ANNs were fed from the information obtained by digital signal processing techniques （Fourier transform）, to identify and classify three distinct classes of defects. Results showed that with the combination of feature extraction by Fourier transformation and classification with neural networks, it is possible to obtain an automatic defect detection system in welded joints with average efficiency.展开更多
GANGLIONEUROMA is considered as the most mature and noninvasive form of neuroblastic tumors. It derives from neural crest cells, and can arise from wherever sympathetic tissue exists, including neck, posterior medias...GANGLIONEUROMA is considered as the most mature and noninvasive form of neuroblastic tumors. It derives from neural crest cells, and can arise from wherever sympathetic tissue exists, including neck, posterior mediastinum, adrenal gland, retroperitoneum and pelvis. The two most common locations for this tumor are retroperitoneum and posterior mediastinum; infrequently it occurs in the intracranial re-gion,2-8 with only three cases has been reported arising from trigeminal nerve.2-4 The current paper presents a 49-year-old male patient with a ganglioneuroma arising from right trigeminal ganglion and extending to the mid-dle-posterior cranial fossa. We summarized the clinical and diagnostic characteristics of this extremely rare tumor, in comparison with the three reported cases in literatures.展开更多
IntroductionSolid-pseudopapillary tumor(SPT)is a very rare primary neoplasmof the pancreas.Franz first described it in 1959.It is usually seen inyoung females.In spite of possible histological findings of malignan-cy,...IntroductionSolid-pseudopapillary tumor(SPT)is a very rare primary neoplasmof the pancreas.Franz first described it in 1959.It is usually seen inyoung females.In spite of possible histological findings of malignan-cy,SPPT typically shows a benign clinical course and a low malig-nant potential.The pathogenesis of these tumors is still controversial.It has been suggested that it might originate from ductal and acinarpancreatic cells,endocrine cells or pluripotential stem cells.展开更多
基金We gratefully acknowledge the financial supports from the National Natural Science Foundation of China(Grant No.49976015).
文摘According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-stands can be identified from the distribution of coral reef ages： 7300 - 6000 cal.aBP, 4800 - 4700 cal.aBP, 4300 - 4200 cal.aBP and 3100 - 2900 cal.aBP. The highest sea level occurred around 7300 - 6700 cal.aBP, and biological-morphological zones took their shape during the stage. The later coral reefs developed in ponds, depressions, and developed outwards on both sides of Luhuitou peninsula. The modern coral reefs are developing in out reef flat and reef-front slope. Moreover, the time of high sea levels in the northern South China Sea recorded by coral reefs in the Luhuitou peninsula can link up with that in other parts of South China Sea. That means the high sea levels in the South China Sea during the Holocene, which are relative to the warming climate, have the global background.
基金Supported by"863"High Technology Development Comittee ofChina (No."863"- 51 1 - 942 - 0 2 4 ) National Natural Science Foun-dation of China (No.50 0 750 64)
文摘A non contact three dimensional measurement method is presented in this paper.This system consists of a laser triangulation probe,a probe head and a coordinate measuring machine (CMM).The measurement principle of the system is discussed,and a system calibration method employing a reference ball is proposed.The geometric model involving four frames is established to calculate the data points based on the reading of the laser probe and position information from the CMM.A measuring experiment for gesso free form surface using this system is carried out.
文摘The dynamic contact resistances of HH52P electromagnetic relays are measured under different ambient air tem- perature. Their diagnostic parameters are extracted and determined. It is found that the ambient air temperature obviously influ- ences some parameters. In order to research its influence on the electrical contact reliability of electromagnetic relay, the statistic analysis is applied to study the static contact resistance, the max of the dynamic contact resistance and the bounce time. It is found that the ambient air temperature regularly influences the three parameters. Thoroughly, the phenomenon is studied and analyzed in the point of material science so as to probe into the essential matter of it.
基金Project(2014QNB18) supported by the Fundamental Research Funds for the Central Universities of ChinaProject(2014CBO46300) supported by the National Basic Research Program of China
文摘Kinematics and dynamics analyses were performed for a spatial 3-revolute joint-revolute joint-clylindric pair(3-RRC) parallel manipulator.This 3-RRC parallel manipulator is composed of a moving platform,a base platform,and three revolute joint-revolute joint-column pair chains which connect the moving platform and the base platform.Firstly,kinematics analysis for 3-RRC parallel manipulator was conducted.Next,on the basis of Lagrange formula,a simply-structured dynamic model of 3-RRC parallel manipulator was derived.Finally,through a calculation example,the variation of motorial parameters of this 3-RRC parallel manipulator,equivalent moment of inertia,driving force/torque and energy consumption was discussed.The research findings have important significance for research and engineering projects such as analyzing dynamic features,mechanism optimization design and control of 3-RRC parallel manipulator.
基金National Natural Science Foundation of China(No.51375338)National Key R&D Program of China(No.2017YFF0108102)
文摘A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the inner and outer surfaces. Since the maximum length of the workpiece can reach 2 000 mm , it is difficult to be clamped and adjusted and easy to produce clamping error. The eccentricity can be up to 1.5 mm, which has an interaction effect with the probe mounting offset. We mainly study the probe offset of the measuring machine and the influence of the workpiece clamping error on the measurement. A method of controlling the offset of the measuring probe is proposed. The effect of the clamping error is eliminated through the space coordinate transformation of the workpiece axis, and the axis is fitted by the least square method. Finally, a common fixture can be realized to meet the clamping requirements of the workpiece.
文摘It is due to the need to ensure the security and integrity of equipment, that the non-destructive tests have been increasingly used in the industrial sector. Among these, the ultrasonic pulse echo technique is the most used in industry, mainly for its simplicity and efficiency. With one transducer only, it is possible to emit the ultrasonic and receive the echo pulse. The ANNs （artificial neural networks） are artificial intelligence techniques that, when properly trained, align themselves to inspection tests becoming a powerful tool in the detection and fault identification. In this work, the echo pulse technique was used to detect discontinuities in welds, where ANNs were fed from the information obtained by digital signal processing techniques （Fourier transform）, to identify and classify three distinct classes of defects. Results showed that with the combination of feature extraction by Fourier transformation and classification with neural networks, it is possible to obtain an automatic defect detection system in welded joints with average efficiency.
基金Supported by National Natural Science Foundation of China(81101034)
文摘GANGLIONEUROMA is considered as the most mature and noninvasive form of neuroblastic tumors. It derives from neural crest cells, and can arise from wherever sympathetic tissue exists, including neck, posterior mediastinum, adrenal gland, retroperitoneum and pelvis. The two most common locations for this tumor are retroperitoneum and posterior mediastinum; infrequently it occurs in the intracranial re-gion,2-8 with only three cases has been reported arising from trigeminal nerve.2-4 The current paper presents a 49-year-old male patient with a ganglioneuroma arising from right trigeminal ganglion and extending to the mid-dle-posterior cranial fossa. We summarized the clinical and diagnostic characteristics of this extremely rare tumor, in comparison with the three reported cases in literatures.
文摘IntroductionSolid-pseudopapillary tumor(SPT)is a very rare primary neoplasmof the pancreas.Franz first described it in 1959.It is usually seen inyoung females.In spite of possible histological findings of malignan-cy,SPPT typically shows a benign clinical course and a low malig-nant potential.The pathogenesis of these tumors is still controversial.It has been suggested that it might originate from ductal and acinarpancreatic cells,endocrine cells or pluripotential stem cells.
