The Experts below are selected from a list of 96450 Experts worldwide ranked by ideXlab platform
Kenji Higashi - One of the best experts on this subject based on the ideXlab platform.
-
effect of grain refinement on tensile ductility in zk60 magnesium alloy under Dynamic Loading
Materials Transactions, 2001Co-Authors: Toshiji Mukai, Koichi Ishikawa, Masashi Yamanoi, Hiroyuki Watanabe, Kenji HigashiAbstract:Magnesium alloys are generally brittle owing to their HCP structure. In this study, improvement of tensile mechanical properties under Dynamic Loading has been demonstrated for a pure magnesium and a ZK60 magnesium alloy. The solution-treated ZK60 alloy exhibits yielding at a Dynamic strain rate of 1.8 x 10 3 s -1 , which was not observed in a pure magnesium. The yield stress of the ZK60 alloy increases at the Dynamic strain rate with a similar slope of Hall-Petch relation at a quasi-static strain rate. Enhancement of ductility can he also achieved by refining grain structures for the ZK60 alloy. The high ductility of the fine-grained alloy is due to the absence of macroscopic cracking at mechanical twin boundaries. It is found that the absorption energy per weight in the fine-grained ZK60 is twice higher than that of high strength aluminum alloys.
-
experimental study of a structural magnesium alloy with high absorption energy under Dynamic Loading
Scripta Materialia, 1998Co-Authors: Toshiji Mukai, T Mohri, Mamoru Mabuchi, Mamoru Nakamura, Koichi Ishikawa, Kenji HigashiAbstract:It has been demonstrated that pure Mg exhibits low ductility under Dynamic Loading at room temperature owing to its HCP structure. Very limited data are currently available for magnesium alloys under Dynamic Loading. In order to be used for structural components, it is necessary to improve the mechanical properties of magnesium alloys. Lahaise et al. reported the yield strength of the AZ91 magnesium alloy increased with refining its microstructure. Mohri et al. has already been reported the ductility enhancement of a Mg-Y-RE(Rare Earth) alloy by hot extrusion. They mentioned the enhancement of ductility is due to the refining microstructure of magnesium. Thus refining microstructure enables to raise the possibility for the development of a structural magnesium alloy with high ductility at Dynamic strain rate. In this paper, the possibility of a fine-grained WE43 magnesium alloy is investigated to raise the high speed impact performance against the foreign object damage by the enhancement of ductility and absorption energy under Dynamic Loading.
H.c. Luong - One of the best experts on this subject based on the ideXlab platform.
-
A 1.5-V 4-GHz Dynamic-Loading regenerative frequency doubler in a 0.35-/spl mu/m CMOS process
IEEE Transactions on Circuits and Systems II: Analog and Digital Signal Processing, 2003Co-Authors: J.m.c. Wong, H.c. LuongAbstract:This paper proposes a new topology of a frequency doubler using a Dynamic-Loading technique to achieve higher operating frequency, larger output swing, larger bandwidth and lower phase noise compared to traditional designs. Implemented in a standard 0.35-/spl mu/m digital CMOS process and at a 1.5-V supply, the proposed frequency doubler measures a maximum operating output frequency of 4 GHz with a bandwidth of 2.4 GHz while consuming a power of 3.7 mW. The single-ended output amplitude ranges from -3.0 to -6.5 dBm, and the phase noise is as low as -111 dBc/Hz at 500-kHz offset.
-
A 1.5-V 4-GHz Dynamic-Loading regenerative frequency doubler in a 0.35-/spl mu/m CMOS process
2002 IEEE MTT-S International Microwave Symposium Digest (Cat. No.02CH37278), 2002Co-Authors: J.m.c. Wong, H.c. LuongAbstract:This paper proposes a new topology of a frequency doubler using a Dynamic-Loading technique to achieve higher operating frequency, larger output swing, larger bandwidth and lower phase noise compared to traditional designs. Implemented in a standard 0.35-/spl mu/m digital CMOS process and at a 1.5-V supply, the proposed frequency doubler measures a maximum operating output frequency of 4 GHz with a bandwidth of 2.4 GHz while consuming a power of 3.7mW. The single-ended output amplitude is ranging from -3.0 to -6.5 dBm, and the phase noise is as low as -111dBc/Hz @ 500kHz offset.
Toshiji Mukai - One of the best experts on this subject based on the ideXlab platform.
-
effect of grain refinement on tensile ductility in zk60 magnesium alloy under Dynamic Loading
Materials Transactions, 2001Co-Authors: Toshiji Mukai, Koichi Ishikawa, Masashi Yamanoi, Hiroyuki Watanabe, Kenji HigashiAbstract:Magnesium alloys are generally brittle owing to their HCP structure. In this study, improvement of tensile mechanical properties under Dynamic Loading has been demonstrated for a pure magnesium and a ZK60 magnesium alloy. The solution-treated ZK60 alloy exhibits yielding at a Dynamic strain rate of 1.8 x 10 3 s -1 , which was not observed in a pure magnesium. The yield stress of the ZK60 alloy increases at the Dynamic strain rate with a similar slope of Hall-Petch relation at a quasi-static strain rate. Enhancement of ductility can he also achieved by refining grain structures for the ZK60 alloy. The high ductility of the fine-grained alloy is due to the absence of macroscopic cracking at mechanical twin boundaries. It is found that the absorption energy per weight in the fine-grained ZK60 is twice higher than that of high strength aluminum alloys.
-
experimental study of a structural magnesium alloy with high absorption energy under Dynamic Loading
Scripta Materialia, 1998Co-Authors: Toshiji Mukai, T Mohri, Mamoru Mabuchi, Mamoru Nakamura, Koichi Ishikawa, Kenji HigashiAbstract:It has been demonstrated that pure Mg exhibits low ductility under Dynamic Loading at room temperature owing to its HCP structure. Very limited data are currently available for magnesium alloys under Dynamic Loading. In order to be used for structural components, it is necessary to improve the mechanical properties of magnesium alloys. Lahaise et al. reported the yield strength of the AZ91 magnesium alloy increased with refining its microstructure. Mohri et al. has already been reported the ductility enhancement of a Mg-Y-RE(Rare Earth) alloy by hot extrusion. They mentioned the enhancement of ductility is due to the refining microstructure of magnesium. Thus refining microstructure enables to raise the possibility for the development of a structural magnesium alloy with high ductility at Dynamic strain rate. In this paper, the possibility of a fine-grained WE43 magnesium alloy is investigated to raise the high speed impact performance against the foreign object damage by the enhancement of ductility and absorption energy under Dynamic Loading.
Yaozu Hu - One of the best experts on this subject based on the ideXlab platform.
-
A study of piezoelectric properties of carbon fiber reinforced concrete and plain cement paste during Dynamic Loading
Cement and Concrete Research, 2000Co-Authors: Mingqing Sun, Qingping Liu, Zhuoqiu Li, Yaozu HuAbstract:\nCarbon fiber reinforced concrete (CFRC) is an intrinsically smart material, which can be used to realize the self-monitoring of concrete structures based on its piezoresistance effect and the Seebeck effect. An experimental study was made to examine the piezoelectric properties of CFRC and plain cement paste. The results show that both CFRC and plain cement paste exhibit piezoelectric behavior, which can be explained in terms of a solid-liquid interface double-layer model. Furthermore, they can sense a large range of Loading rates with high sensitivity. The materials are good sensors for monitoring the Dynamic Loading. Therefore, a new method to make smart concrete structures can be developed.
Jeffrey C Lotz - One of the best experts on this subject based on the ideXlab platform.
-
biological response of the intervertebral disc to Dynamic Loading
Journal of Biomechanics, 2004Co-Authors: Andrew J L Walsh, Jeffrey C LotzAbstract:Abstract Disc degeneration is a chronic remodeling process that results in alterations of matrix composition and decreased cellularity. This study tested the hypothesis that Dynamic mechanical forces are important regulators in vivo of disc cellularity and matrix synthesis. A murine model of Dynamic Loading was developed that used an external Loading device to cyclically compress a single disc in the tail. Loads alternated at a 50% duty cycle between 0 MPa and one of two peak stresses (0.9 or 1.3 MPa) at one of two frequencies (0.1 or 0.01 Hz) for 6 h per day for 7 days. An additional group received static compression at 1.3 MPa for 3 h/day for 7 days. A control group wore the device with no Loading. Sections of treated discs were analyzed for morphology, proteoglycan content, apoptosis, cell areal density, and aggrecan and collagen II gene expression. Dynamic Loading induced differential effects that depended on frequency and stress. No significant changes to morphology, proteoglycan content or cell death were found after Loading at 0.9 MPa, 0.1 Hz. Loading at lower frequency and/or higher stress increased proteoglycan content, matrix gene expression and cell death. The results have implications in the prevention of intervertebral disc degeneration, suggesting that Loading conditions may be optimized to promote maintenance of normal structure and function.
