Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteris...Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation accuracy.However,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for NCS.The TdisULAs structure generally consists of three ULAs,which are appropriately placed.The proposed antenna array approach fully exploits the non-circular characteristics of the sources.Given the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors.Advantageously,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form expressions.Moreover,the proposed array also produces a filled resulting co-array.Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.展开更多
A system architecture of solid-based NC simulation for milling machining is given, the function of which is composed of cutting simulation of different cutters, such as flat-end cutters, ball-end cutters, dome-end cut...A system architecture of solid-based NC simulation for milling machining is given, the function of which is composed of cutting simulation of different cutters, such as flat-end cutters, ball-end cutters, dome-end cutters, angle cutters and drill cutters, rapid pre-checking of interference, detection of collision, and visualization of over cut in the stock. A new method based on the design model is raised to detect the collision and pre-check the interference during NC milling machining. A special problem about the construction of a cutter′s swept volume, self-intersection is discussed. All the work on the construction, the subtraction and the display of solids is accomplished with the help of ACIS 3-D modeling.展开更多
基金supported by the National Natural Science Foundation of China(62031017,61971221)the Fundamental Research Funds for the Central Universities of China(NP2020104)。
文摘Non-uniform linear array(NULA)configurations are well renowned due to their structural ability for providing increased degrees of freedom(DOF)and wider array aperture than uniform linear arrays(ULAs).These characteristics play a significant role in improving the direction-of-arrival(DOA)estimation accuracy.However,most of the existing NULA geometries are primarily applicable to circular sources(CSs),while they limitedly improve the DOF and continuous virtual aperture for noncircular sources(NCSs).Toward this purpose,we present a triaddisplaced ULAs(Tdis-ULAs)configuration for NCS.The TdisULAs structure generally consists of three ULAs,which are appropriately placed.The proposed antenna array approach fully exploits the non-circular characteristics of the sources.Given the same number of elements,the Tdis-ULAs design achieves more DOF and larger hole-free co-array aperture than its sparse array competitors.Advantageously,the number of uniform DOF,optimal distribution of elements among the ULAs,and precise element positions are uniquely determined by the closed-form expressions.Moreover,the proposed array also produces a filled resulting co-array.Numerical simulations are conducted to show the performance advantages of the proposed Tdis-ULAs configuration over its counterpart designs.
文摘A system architecture of solid-based NC simulation for milling machining is given, the function of which is composed of cutting simulation of different cutters, such as flat-end cutters, ball-end cutters, dome-end cutters, angle cutters and drill cutters, rapid pre-checking of interference, detection of collision, and visualization of over cut in the stock. A new method based on the design model is raised to detect the collision and pre-check the interference during NC milling machining. A special problem about the construction of a cutter′s swept volume, self-intersection is discussed. All the work on the construction, the subtraction and the display of solids is accomplished with the help of ACIS 3-D modeling.
