Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexi...Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexible assembly system is just beginning in our country recently. To meet the requirements of automated posture alignment and join in digital assembly system for large aircraft components, a novel fitting fixture called 3-axis actuator is developed. On the basis of the actuators, three kinds of posture alignment system for large aircraft components are proposed, including the non-redundant system, the redundant actuating system, and the redundant leg system, and their constitutions and properties are introduced. Through deriving the feeding transmission stiffness model of single actuator and analyzing the inverse kinematics of these systems, the relationship between the external force and the changes of position and orientation of large aircraft component is obtained, and then the postural alignment stiffness models are established. With the method mentioned above, the postural alignment stiffness of three systems is computed by using the algebraic formulate, and the results show that redundant properties can increase system＇s postural alignment stiffness. As an example, a optimized layout of the assembly system for a given model of aircraft is developed, the results of application show that the layout has many advantages, such as high accuracy, stiffness, stability, reliability, efficiency and flexible, which can satisfy the requirement of aircraft digital assembly system well. The proposed study of postural alignment stiffness for different systems can supply the theoretic support for the optimization layout design of aircraft digital assembly system, and contribute to evaluate the system working performance of systems.展开更多
This study proposes a novel AC vector magnetometer developed using a low-resource magneto-impedance sensor for China’s Feng-Yun meteorological satellite(FY-3E).It was calibrated and characterized to determine its per...This study proposes a novel AC vector magnetometer developed using a low-resource magneto-impedance sensor for China’s Feng-Yun meteorological satellite(FY-3E).It was calibrated and characterized to determine its performance parameters.The total weight of the AC vector magnetometer is 51 g(the aluminum box excluded),while the total power consumption is 310 m W.The proposed AC vector magnetometer can detect magnetic field variations in the range of±1000 nT and noise power spectral density of≤50 pT/Hz^(1/2)@1 Hz.Furthermore,the proposed device has a maximum nonlinearity of≤0.71‰over the entire range and a nonorthogonality error of 3.07 nT or 0.15%(root mean square).The total dose hardness of the sensor is≥30 krad(Si).Furthermore,we propose the first survey results of a magnetometer equipped aboard a Chinese FY-3E satellite in a Sunsynchronous orbit.The data revealed that the AC vector magnetometer can detect transient physical signals such as quasistatic field-aligned currents(~50 nT)and waves at the auroral latitudes.These features render the proposed AC vector magnetometer suitable for space-based applications,particularly those involving the study of geomagnetic activity.展开更多
A ground magnetic survey was carried out to investigate the presence of iron ore at a location (Lat. 7.99883°N to Lat. 7.99933°N, Long. 3.57900°E to Long. 3.57990°E) in Iseyin, Oyo State, South-wes...A ground magnetic survey was carried out to investigate the presence of iron ore at a location (Lat. 7.99883°N to Lat. 7.99933°N, Long. 3.57900°E to Long. 3.57990°E) in Iseyin, Oyo State, South-western Nigeria. Ten magnetic traverses each 100 m long at a separation of 5 m were run West-East. Magnetic intensity was taken at intervals of 10 m along each traverse line using the proton precession magnetometer (G-856 AX). The measured magnetic field data were corrected for drift and were presented as profiles. The profiles were interpreted by calculating the depth to the top of anomalies. The data obtained were used to construct magnetic anomaly maps in 2D and 3D. The magnetic survey results delineated this location into some high and low magnetic field intensity regions. The regions of high magnetic field anomaly indicated the presence of materials with high susceptibility which was suspected to be iron compounds. The quantitative and qualitative analyses on interpretations of field data collected were given, while these results provided values for the total component measurements of ground magnetic anomaly that widely ranged between a maximum positive peak result of 8 nT and to a minimum negative peak result of —6 nT. Using Peter’s half slope technique, depth to the basement was assessed, which actually provided a maximum depth to basement of 6.25 m. From the knowledge of the geology of the area and also, the magnetic survey employed information, therefore, we can finally conclude that, the study area is under laid by geologic structures which favour the accumulation of iron-ore minerals deposit at Oke-Aro area in Iseyin.展开更多
This paper describes a wood-wood spatial joining system adapted to digital fabrication which has been designated the“Spatial Masterkey”.The wood stereotomy of the joints between the different pieces that make up thi...This paper describes a wood-wood spatial joining system adapted to digital fabrication which has been designated the“Spatial Masterkey”.The wood stereotomy of the joints between the different pieces that make up this joining system is inspired by a three-dimensional puzzle called“snowflake”.The production process used in the masterkey system can be carried out using only a 3-axis CNC milling machine—a relatively affordable and easily accessible tool.By using digital manufacturing for the execution of wood-wood joints,several benefits are obtained including faster machining and greater cutting precision and uniformity in the products produced.These advantages make this joining system both economically competitive and environmentally friendly.Additionally,the versatility of this joining system means that its configuration can be adapted to a wide range of casuistry of encounters between members,which means that it can be used for a number of spatial assemblies.This includes,but is not limited to,the spatial module presented in this document.展开更多
A facile and green synthetic approach for fabrication of starch-stabilized magnetite nanoparticles was implemented at moderate temperature. This synthesis involved the use of iron salts, potato starch,sodium hydroxide...A facile and green synthetic approach for fabrication of starch-stabilized magnetite nanoparticles was implemented at moderate temperature. This synthesis involved the use of iron salts, potato starch,sodium hydroxide and deionized water as iron precursors, stabilizer, reducing agent and solvent respectively. The nanoparticles（NPs） were characterized by UV-vis, PXRD, HR-TEM, FESEM, EDX, VSM and FT-IR spectroscopy. The ultrasonic assisted co-precipitation technique provides well formation of highly distributed starch/Fe3O4-NPs. Based on UV–vis analysis, the sample showed the characteristic of surface plasmon resonance in the presence of Fe3O4-NPs. The PXRD pattern depicted the characteristic of the cubic lattice structure of Fe3O4-NPs. HR-TEM analysis showed the good dispersion of NPs with a mean diameter and standard deviation of 10.68 4.207 nm. The d spacing measured from the lattice images were found to be around 0.30 nm and 0.52 nm attributed to the Fe3O4 and starch, respectively. FESEM analysis confirmed the formation of spherical starch/Fe3O4-NPs with the emission of elements of C, O and Fe by EDX analysis. The magnetic properties illustrated by VSM analysis indicated that the as synthesized sample has a saturation magnetization and coercivity of 5.30 emu/g and 22.898 G respectively.Additionally, the FTIR analysis confirmed the binding of starch with Fe3O4-NPs. This method was cost effective, facile and eco-friendly alternative for preparation of NPs.展开更多
文摘Aircraft digital flexible assembly fixture and technologies are widely used in developed countries, while the traditional jig-based assembly mode is still used in China. The application study of aircraft digital flexible assembly system is just beginning in our country recently. To meet the requirements of automated posture alignment and join in digital assembly system for large aircraft components, a novel fitting fixture called 3-axis actuator is developed. On the basis of the actuators, three kinds of posture alignment system for large aircraft components are proposed, including the non-redundant system, the redundant actuating system, and the redundant leg system, and their constitutions and properties are introduced. Through deriving the feeding transmission stiffness model of single actuator and analyzing the inverse kinematics of these systems, the relationship between the external force and the changes of position and orientation of large aircraft component is obtained, and then the postural alignment stiffness models are established. With the method mentioned above, the postural alignment stiffness of three systems is computed by using the algebraic formulate, and the results show that redundant properties can increase system＇s postural alignment stiffness. As an example, a optimized layout of the assembly system for a given model of aircraft is developed, the results of application show that the layout has many advantages, such as high accuracy, stiffness, stability, reliability, efficiency and flexible, which can satisfy the requirement of aircraft digital assembly system well. The proposed study of postural alignment stiffness for different systems can supply the theoretic support for the optimization layout design of aircraft digital assembly system, and contribute to evaluate the system working performance of systems.
基金supported by the National Natural Science Foundation of China (Grant No.42074223)。
文摘This study proposes a novel AC vector magnetometer developed using a low-resource magneto-impedance sensor for China’s Feng-Yun meteorological satellite(FY-3E).It was calibrated and characterized to determine its performance parameters.The total weight of the AC vector magnetometer is 51 g(the aluminum box excluded),while the total power consumption is 310 m W.The proposed AC vector magnetometer can detect magnetic field variations in the range of±1000 nT and noise power spectral density of≤50 pT/Hz^(1/2)@1 Hz.Furthermore,the proposed device has a maximum nonlinearity of≤0.71‰over the entire range and a nonorthogonality error of 3.07 nT or 0.15%(root mean square).The total dose hardness of the sensor is≥30 krad(Si).Furthermore,we propose the first survey results of a magnetometer equipped aboard a Chinese FY-3E satellite in a Sunsynchronous orbit.The data revealed that the AC vector magnetometer can detect transient physical signals such as quasistatic field-aligned currents(~50 nT)and waves at the auroral latitudes.These features render the proposed AC vector magnetometer suitable for space-based applications,particularly those involving the study of geomagnetic activity.
文摘A ground magnetic survey was carried out to investigate the presence of iron ore at a location (Lat. 7.99883°N to Lat. 7.99933°N, Long. 3.57900°E to Long. 3.57990°E) in Iseyin, Oyo State, South-western Nigeria. Ten magnetic traverses each 100 m long at a separation of 5 m were run West-East. Magnetic intensity was taken at intervals of 10 m along each traverse line using the proton precession magnetometer (G-856 AX). The measured magnetic field data were corrected for drift and were presented as profiles. The profiles were interpreted by calculating the depth to the top of anomalies. The data obtained were used to construct magnetic anomaly maps in 2D and 3D. The magnetic survey results delineated this location into some high and low magnetic field intensity regions. The regions of high magnetic field anomaly indicated the presence of materials with high susceptibility which was suspected to be iron compounds. The quantitative and qualitative analyses on interpretations of field data collected were given, while these results provided values for the total component measurements of ground magnetic anomaly that widely ranged between a maximum positive peak result of 8 nT and to a minimum negative peak result of —6 nT. Using Peter’s half slope technique, depth to the basement was assessed, which actually provided a maximum depth to basement of 6.25 m. From the knowledge of the geology of the area and also, the magnetic survey employed information, therefore, we can finally conclude that, the study area is under laid by geologic structures which favour the accumulation of iron-ore minerals deposit at Oke-Aro area in Iseyin.
基金The authors received financial support from the Department of Architecture of the University of the Basque Country UPV/EHU for the translation of this article.
文摘This paper describes a wood-wood spatial joining system adapted to digital fabrication which has been designated the“Spatial Masterkey”.The wood stereotomy of the joints between the different pieces that make up this joining system is inspired by a three-dimensional puzzle called“snowflake”.The production process used in the masterkey system can be carried out using only a 3-axis CNC milling machine—a relatively affordable and easily accessible tool.By using digital manufacturing for the execution of wood-wood joints,several benefits are obtained including faster machining and greater cutting precision and uniformity in the products produced.These advantages make this joining system both economically competitive and environmentally friendly.Additionally,the versatility of this joining system means that its configuration can be adapted to a wide range of casuistry of encounters between members,which means that it can be used for a number of spatial assemblies.This includes,but is not limited to,the spatial module presented in this document.
基金supported by the Malaysian Ministry of High Education and Universiti Teknologi Malaysia (UTM) under Tier 1 grant (No. Q.K130000.2543.12H95)
文摘A facile and green synthetic approach for fabrication of starch-stabilized magnetite nanoparticles was implemented at moderate temperature. This synthesis involved the use of iron salts, potato starch,sodium hydroxide and deionized water as iron precursors, stabilizer, reducing agent and solvent respectively. The nanoparticles（NPs） were characterized by UV-vis, PXRD, HR-TEM, FESEM, EDX, VSM and FT-IR spectroscopy. The ultrasonic assisted co-precipitation technique provides well formation of highly distributed starch/Fe3O4-NPs. Based on UV–vis analysis, the sample showed the characteristic of surface plasmon resonance in the presence of Fe3O4-NPs. The PXRD pattern depicted the characteristic of the cubic lattice structure of Fe3O4-NPs. HR-TEM analysis showed the good dispersion of NPs with a mean diameter and standard deviation of 10.68 4.207 nm. The d spacing measured from the lattice images were found to be around 0.30 nm and 0.52 nm attributed to the Fe3O4 and starch, respectively. FESEM analysis confirmed the formation of spherical starch/Fe3O4-NPs with the emission of elements of C, O and Fe by EDX analysis. The magnetic properties illustrated by VSM analysis indicated that the as synthesized sample has a saturation magnetization and coercivity of 5.30 emu/g and 22.898 G respectively.Additionally, the FTIR analysis confirmed the binding of starch with Fe3O4-NPs. This method was cost effective, facile and eco-friendly alternative for preparation of NPs.
