A jamming signal such as single and multiple Continuous-Wave (CW and MCW) interferences have been shown to have severe effects on the quality of the received signal in wireless communication. This paper presents an ap...A jamming signal such as single and multiple Continuous-Wave (CW and MCW) interferences have been shown to have severe effects on the quality of the received signal in wireless communication. This paper presents an approach of a low-complexity algorithm that compares the performances of using Adaptive Notch Filter (ANF) direct and lattice forms structures based on second-order Infinite Impulse Response (IIR) Notch Filter (NF) for the detection and mitigation of CW and MCW interferences in QPSK communication systems. The approach method consists of two ANFs, adaptive IIR NF and adaptive IIR NF . The present algorithm can estimate and mitigate each CWI and computer their power in Time-Domain (TD). In results for performance comparison, the lattice IIR NF structure outperforms the direct IIR NF structure for detection and removal jamming and has a better Bit Error Ratio (BER). Furthermore, compared with the case of full suppression (), both cases (direct and lattice form) work better for low and high-power jammers. Also, compared to the case without an IIR NF, the presented algorithm can detect and mitigate, track hopping frequency interference, and improve BER performance.展开更多
Straight plates, hollow columns, ear-like blade tips, twist plates withdirectional solidification microstructure made of Rene 95 superalloys were successfully fabricatedon Nickel-base superalloy and DD3 substrates, re...Straight plates, hollow columns, ear-like blade tips, twist plates withdirectional solidification microstructure made of Rene 95 superalloys were successfully fabricatedon Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for productionof the parts with corresponding shapes were obtained. The fabrication precision was high and thecomponents were compact. The solidification microstructure of the parts was analyzed by opticalmicroscopy. The results show that the solidification microstructure is composed of columnardendrites, by epitaxial growth onto the directional solidification substrates. The crystallographyorientation of the parts was parallel to that of the substrates. The primary arm spacing was about10 mum, which is in the range of superfine dendrites, and the secondary arm was small or evendegenerated. It is concluded that the laser metal forming technique provides a method to manufacturedirectional solidification components.展开更多
The specific Fe-based alloy for direct metal forming was designed and prepared under multi-layer cladding condition.The powder was designed for getting the better formability,toughness and hardness.The experiment used...The specific Fe-based alloy for direct metal forming was designed and prepared under multi-layer cladding condition.The powder was designed for getting the better formability,toughness and hardness.The experiment used KR6 robot and NW5000 digital power supply as the hardware environment.Microstructure and hardness of the layer formed by different powder were analyzed by using X-ray diffraction (XRD) and Transmission Electron Microscope (TEM).The result shows that thermal expansion coefficient correlated with processing formability is not linearity.Hardness of the layers is correlated to elements phase of the coatings was formed by γ(FeNi) and α(FeCrNi),and a little Cr23C6、Fe3Si and MoO2.展开更多
Rapid prototyping technology can greatly improve the actual processing industrial prototype; this paper introduces the main principle, characteristics and technology of rapid prototype manufacturing. The current rapid...Rapid prototyping technology can greatly improve the actual processing industrial prototype; this paper introduces the main principle, characteristics and technology of rapid prototype manufacturing. The current rapid prototype manufacturing products and production problems are analyzed. Because of the direct metal forming process have the characteristic of point by point, surfacing with stack molding manufacturing layer by layer, so it is suitable for complex shape parts two-dimensional or three-dimensional functionally gradient materials manufacturing.展开更多
The Liaoji Proterozoic rift is an inter-intracontinenatl rift developed from Archean granite-greenstone tectonic regime and contains many important mineral deposits of U, B, magnesite, Pb-Zn, Au, Ag, Co and P. These d...The Liaoji Proterozoic rift is an inter-intracontinenatl rift developed from Archean granite-greenstone tectonic regime and contains many important mineral deposits of U, B, magnesite, Pb-Zn, Au, Ag, Co and P. These deposits were formed as the result of late mobilization, transportation and concentfation of the previously enriched ore-forming mate- rials in several ore-bearing formations formed during the rift stage. So the metallogeny of these deposits in the rift shows both inheritance and new generation of the ore-forming materials. In future ore-searching practice, attentions should be paid on the studies of the ore-bearing formations in the rift, on the multiple stages of metallogeny and and on multiple derivations of the ore-forming materials.展开更多
The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In o...The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.展开更多
Rene95 powder and different substrates were selected to be conducted by the laser metal forming technique. It is found that the cladding layers with either columnar or equiaxed grains can be obtained under different s...Rene95 powder and different substrates were selected to be conducted by the laser metal forming technique. It is found that the cladding layers with either columnar or equiaxed grains can be obtained under different solidification conditions. As the crystallography orientation of the substrate influences that of the cladding layers strongly. Multi-grain cladding layers can be obtained on the multi-grain substrate, while directional solidification columnar or even single crystal cladding layer can be achieved on the directional solidification or single crystal substrate.The mechanism of microstructure formation in the cladding layer was furtherly investigated according to the columnar/equiaxed transition profile. In addition,an ear-like single crystal component was manufactured using the DD3 single crystal as substrate. The yield strength at room temperature was examined on the heat-treated slice sample. The results indicate that the yield strength is about 97.9% of that of the powder metallurgical tensile sample while the plasticity overpasses 80% of the powder metallurgical tensile sample.展开更多
Today, the significance of the wireless communication is known all over the world. In order to achieve the better communication, many techniques and methods have been introduced. Among these techniques, smart/adaptive...Today, the significance of the wireless communication is known all over the world. In order to achieve the better communication, many techniques and methods have been introduced. Among these techniques, smart/adaptive antennas are trending topic in the research domain. The smart antennas consist of various antennas arrays and have the ability to optimize the radia-tion and reception of the desired signals dynamically. Also, in order to avoid or mitigate the interferences, smart antennas can introduce nulls in the in-terferers direction by adaptive updating of the weights linked at every antenna element. The smart antennas can also enhance the quality of reception and reduce the dropped calls. This paper discusses the various survey topics related to smart antennas, Adaptive Beam Forming (ABF) algorithm etc. Also the various existing researches are discussed to know the research gap for future research scope.展开更多
The paper introduces the origin of the word of Direct Digital Manufacturing and other forms of address, and the working principles of Direct Digital Manufacturing technology and major types of the technology, hard- wa...The paper introduces the origin of the word of Direct Digital Manufacturing and other forms of address, and the working principles of Direct Digital Manufacturing technology and major types of the technology, hard- ware and software development, use of materials, applications, market growth and its development prospects. Focused presentations of Direct Digital Manufacturing （additive manufacturing） compared to traditional mechani- cal manufacturing industry in the use of prices, processing speed, reliability and cost advantages and characteris- tics. Particularly the significant challenges and competitiveness of Direct Digital Manufacturing technology in the processing of any complexity created directly the number of objects, internal structure and channel function, as well as the shape of the chassis components and structure of the matching and optimization.展开更多
文摘A jamming signal such as single and multiple Continuous-Wave (CW and MCW) interferences have been shown to have severe effects on the quality of the received signal in wireless communication. This paper presents an approach of a low-complexity algorithm that compares the performances of using Adaptive Notch Filter (ANF) direct and lattice forms structures based on second-order Infinite Impulse Response (IIR) Notch Filter (NF) for the detection and mitigation of CW and MCW interferences in QPSK communication systems. The approach method consists of two ANFs, adaptive IIR NF and adaptive IIR NF . The present algorithm can estimate and mitigate each CWI and computer their power in Time-Domain (TD). In results for performance comparison, the lattice IIR NF structure outperforms the direct IIR NF structure for detection and removal jamming and has a better Bit Error Ratio (BER). Furthermore, compared with the case of full suppression (), both cases (direct and lattice form) work better for low and high-power jammers. Also, compared to the case without an IIR NF, the presented algorithm can detect and mitigate, track hopping frequency interference, and improve BER performance.
基金This research was financially supported by the National High Technology Research and Development Program of China (No.2001AA337020)the Development Plan of State Key Fundamental Research of China (No. G2000067205-3)
文摘Straight plates, hollow columns, ear-like blade tips, twist plates withdirectional solidification microstructure made of Rene 95 superalloys were successfully fabricatedon Nickel-base superalloy and DD3 substrates, respectively. The processing conditions for productionof the parts with corresponding shapes were obtained. The fabrication precision was high and thecomponents were compact. The solidification microstructure of the parts was analyzed by opticalmicroscopy. The results show that the solidification microstructure is composed of columnardendrites, by epitaxial growth onto the directional solidification substrates. The crystallographyorientation of the parts was parallel to that of the substrates. The primary arm spacing was about10 mum, which is in the range of superfine dendrites, and the secondary arm was small or evendegenerated. It is concluded that the laser metal forming technique provides a method to manufacturedirectional solidification components.
文摘The specific Fe-based alloy for direct metal forming was designed and prepared under multi-layer cladding condition.The powder was designed for getting the better formability,toughness and hardness.The experiment used KR6 robot and NW5000 digital power supply as the hardware environment.Microstructure and hardness of the layer formed by different powder were analyzed by using X-ray diffraction (XRD) and Transmission Electron Microscope (TEM).The result shows that thermal expansion coefficient correlated with processing formability is not linearity.Hardness of the layers is correlated to elements phase of the coatings was formed by γ(FeNi) and α(FeCrNi),and a little Cr23C6、Fe3Si and MoO2.
文摘Rapid prototyping technology can greatly improve the actual processing industrial prototype; this paper introduces the main principle, characteristics and technology of rapid prototype manufacturing. The current rapid prototype manufacturing products and production problems are analyzed. Because of the direct metal forming process have the characteristic of point by point, surfacing with stack molding manufacturing layer by layer, so it is suitable for complex shape parts two-dimensional or three-dimensional functionally gradient materials manufacturing.
文摘The Liaoji Proterozoic rift is an inter-intracontinenatl rift developed from Archean granite-greenstone tectonic regime and contains many important mineral deposits of U, B, magnesite, Pb-Zn, Au, Ag, Co and P. These deposits were formed as the result of late mobilization, transportation and concentfation of the previously enriched ore-forming mate- rials in several ore-bearing formations formed during the rift stage. So the metallogeny of these deposits in the rift shows both inheritance and new generation of the ore-forming materials. In future ore-searching practice, attentions should be paid on the studies of the ore-bearing formations in the rift, on the multiple stages of metallogeny and and on multiple derivations of the ore-forming materials.
基金Supported by National Natural Science Foundation of China(Grant No.51335009)Major National Science and Technology Project of China(Grant No.2011ZX04001-011)
文摘The existing plastic forming equipment are mostly driven by traditional AC motors with long trans- mission chains, low efficiency, large size, low precision and poor dynamic response are the common disadvantages. In order to realize high performance forming processes, the driving device should be improved, especially for com- plicated processing motions. Based on electric servo direct drive technology, a novel AC servo rotating and linear composite driving device is proposed, which features implementing both spindle rotation and feed motion with- out transmission, so that compact structure and precise control can be achieved. Flux switching topology is employed in the rotating drive component for strong robustness, and fractional slot is employed in the linear direct drive component for large force capability. Then the mechanical structure for compositing rotation and linear motion is designed. A device prototype is manufactured, machining of each component and the whole assembly are presented respectively. Commercial servo amplifiers are utilized to construct the control system of the proposed device. To validate the effectiveness of the proposed composite driving device, experimental study on thedynamic test benches are conducted. The results indicate that the output torque can attain to 420 N-m and the dynamic tracking errors are less than about 0.3 rad in the rotating drive, the dynamic tracking errors are less than about 1.6 mm in the linear feed. The proposed research provides a method to construct high efficiency and accu- racy direct driving device in plastic forming equipment.
文摘Rene95 powder and different substrates were selected to be conducted by the laser metal forming technique. It is found that the cladding layers with either columnar or equiaxed grains can be obtained under different solidification conditions. As the crystallography orientation of the substrate influences that of the cladding layers strongly. Multi-grain cladding layers can be obtained on the multi-grain substrate, while directional solidification columnar or even single crystal cladding layer can be achieved on the directional solidification or single crystal substrate.The mechanism of microstructure formation in the cladding layer was furtherly investigated according to the columnar/equiaxed transition profile. In addition,an ear-like single crystal component was manufactured using the DD3 single crystal as substrate. The yield strength at room temperature was examined on the heat-treated slice sample. The results indicate that the yield strength is about 97.9% of that of the powder metallurgical tensile sample while the plasticity overpasses 80% of the powder metallurgical tensile sample.
文摘Today, the significance of the wireless communication is known all over the world. In order to achieve the better communication, many techniques and methods have been introduced. Among these techniques, smart/adaptive antennas are trending topic in the research domain. The smart antennas consist of various antennas arrays and have the ability to optimize the radia-tion and reception of the desired signals dynamically. Also, in order to avoid or mitigate the interferences, smart antennas can introduce nulls in the in-terferers direction by adaptive updating of the weights linked at every antenna element. The smart antennas can also enhance the quality of reception and reduce the dropped calls. This paper discusses the various survey topics related to smart antennas, Adaptive Beam Forming (ABF) algorithm etc. Also the various existing researches are discussed to know the research gap for future research scope.
文摘The paper introduces the origin of the word of Direct Digital Manufacturing and other forms of address, and the working principles of Direct Digital Manufacturing technology and major types of the technology, hard- ware and software development, use of materials, applications, market growth and its development prospects. Focused presentations of Direct Digital Manufacturing （additive manufacturing） compared to traditional mechani- cal manufacturing industry in the use of prices, processing speed, reliability and cost advantages and characteris- tics. Particularly the significant challenges and competitiveness of Direct Digital Manufacturing technology in the processing of any complexity created directly the number of objects, internal structure and channel function, as well as the shape of the chassis components and structure of the matching and optimization.
