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151.
152.
Fault-tolerant switched reluctance motor drive using adaptive fuzzy logic controller 总被引:5,自引:0,他引:5
Mir S. Islam M.S. Sebastian T. Husain I. 《Power Electronics, IEEE Transactions on》2004,19(2):289-295
An adaptive fuzzy controller has been designed to develop a high-performance fault-tolerant switched reluctance motor (SRM) drive. The fuzzy controller continuously adapts its properties to regulate the machine torque as desired by the drive system even under fault conditions. The adaptation of the fuzzy membership functions results in extended conduction period and increased peak current of the healthy phases to deliver the commanded torque, as much as possible. The adaptive fuzzy controller provides smooth torque output with minimum ripple, even under fault conditions, yielding a high-performance SRM drive with fault-tolerant capability. 相似文献
153.
A microwave (MW) preheating mechanism of anisotropic conductive adhesive film (ACF) has been introduced in order to reduce the bonding temperature for flip chip technology. Thermal curing of epoxy shows a very sluggish and non-uniform curing kinetics at the beginning of the curing reaction, but the rate increases with time and hence requires higher temperature. On the other hand MW radiation has the advantage of uniform heating rate during the cycle. In view of this, MW preheating (for 2/3 s) of ACF prior to final bonding has been applied to examine the electrical and mechanical performance of the bond. Low MW power has been used (80 and 240 W) to study the effect of the MW preheating. It has been found that 170 °C can be used for flip chip bonding instead of 180 °C (standard temperature for flip chip bonding) for MW preheating time and power used in this study. The contact resistance (0.015–0.025 Ω) is low in these samples where the standard resistance is 0.017 Ω (bonded at 180 °C without prior MW preheating). The shear forces at breakage were satisfactory (152–176 N) for the samples bonded at 170 °C with MW preheating, which is very close and even higher than the standard sample (173.3 N). For MW preheating time of 2 s, final bonding at 160 °C can also be used because of its low contact resistance (0.022–0.032 Ω), but the bond strength (137.3–145 N) is somewhat inferior to the standard one. 相似文献
154.
A Islam M Mustafa A Mustafa T Olsson B Winblad A Adem 《Canadian Metallurgical Quarterly》1997,8(4):987-990
The neuroendocrine and the immune systems are interconnected. Monoclonal antibodies against major histocompatibility complex (MHC) class I, class II, CD4, CD8, pan T cells, and macrophages were used for immunostaining brains from adrenalectomized (ADX) and shamoperated rats to investigate the potential involvement of the immune/inflammatory mechanisms in the neurodegeneration of hippocampus after ADX. Our results demonstrate upregulation of MHC class II, CD4 antigens and activated microglial marker-ED1 expression selectively in the hippocampus after ADX. The absence of CD5 reactivity precludes that these activated cells were T lymphocytes. The activated microglial cells may either be instrumental in the hippocampal neuronal loss or activated secondarily to the neuronal degeneration after long-term adrenalectomy. 相似文献
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157.
Cu-containing solder alloys have been used to identify their interfacial reactions with electroless NiP. As-reflowed, AuSn4 intermetallic compounds (IMCs) are formed in the Sn-Cu and Sn-Ag-Cu solders, but in the cases of Sn-Ag-Cu-In, In-Sn-Au IMCs
are formed and are uniformly distributed in the solder. Different types of IMCs such as high-Cu (>30 at.%), medium-Cu (30-15
at.%), and low-Cu (<15 at.%) containing IMCs are formed at the interface. High-Cu and medium-Cu containing ternary intermetallic
compounds (TIMCs) are found in the Sn-Cu and Sn-Ag-Cu solder joints, respectively. Medium-Cu containing quaternary intermetallic
compounds (QIMCs) are found in the Sn-Ag-Cu-In joints. Initially, TIMCs and QIMCs have higher growth rates, resulting in the
entrapment of some Pb-rich phase in the high-Cu containing TIMCs and some In-Sn-Au phase in the QIMCs. High-Cu containing
TIMCs have a lower growth rate and consume less of the NiP layer. The spalling of medium-Cu containing TIMCs in the Sn-Ag-Cu
solder increases both the growth rate of TIMCs and the consumption rate of the NiP layer. Low-Cu containing QIMCs in the Sn-Ag-Cu-In
solder are stable on P-rich Ni and reduce the dissolution rate of the NiP layer. Consumption of the NiP layer can be reduced
by adding Cu or In, because of the changes of the interfacial IMCs phases, which are stable and adhere well to the P-rich
Ni layer during reflow. 相似文献
158.
159.
160.
Anisotropic conductive adhesive film (ACF) can be preheated by microwave (MW) radiation in order to reduce the bonding time
for flip-chip technology. Due to sluggish and nonuniform curing kinetics at the beginning of the curing reaction, thermal
curing of epoxy is more time consuming. Therefore, MW radiation may be more effective, due to its uniform heating rate during
the cycle. In this paper, MW preheating (for 1–4 sec) of ACF prior to final bonding has been applied to determine the electrical
and mechanical performance of the bond. Powers of 80 and 240 W MW were used to study the effect of the MW preheating. A final
bonding time of 6–7 sec can be used for flip chip on flex bonding instead of 10–15 sec (standard time for flip chip bonding)
for MW preheating time and power used in this study. The contact resistance (as low as 0.01) is low in these samples, whereas
the standard resistance is 0.017 ohm (bonded at 180°C for 10 sec without prior MW preheating). The shear forces at breakage
were satisfactory (0.167–0.183 KN) for the samples bonded for 6–7 sec with MW preheating. This is very close and even higher
than the standard sample (0.173 KN). For MW preheating power of 80 W and sweeping time of 2 sec, final bonding at 6 sec can
also be used because of its low contact resistance (0.019 ohm). Scanning electron microscope (SEM) investigation of microjoints
and fracture surface shows uneven distribution of conductive particles and thick bond lines in samples bonded for 5 sec (with
MW preheating). Samples treated with MW radiation (80 W and 2–3 sec time) serve as evidence that well-distributed particles
along with thin bond lines cause low contact resistance and high joint strength. 相似文献