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Ｍｎ Ａｌ Ｃ磁体具有力学强度高、耐大气腐蚀性好、密度小 (5Ｍｇ/ｍ3)并且机械加工性好等优点 ,所以广泛用于高速旋转体之类重视强度可靠性的用途上。历来采用铸造→固溶热处理→挤压法制造 ,但在铸锭方面有不少问题 ,所以人们长期以来一直寻求新的生产工艺。近年来开发了利用气体雾化粉末的“粉末挤压法” ,能制造沿易磁化轴优先取向的Ｍｎ Ａｌ Ｃ合金磁体 ,适合批量生产。日本山阳特殊钢公司采用比气体雾化制粉的冷凝速度更大的熔体单辊旋淬法 ,首先制得薄带随后磨成粉末 ,最后用温挤压法制成磁体。测量了这种磁体的磁特性 ,研究用的母… 相似文献
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In order to save energy consumption of two-way amplifier forward （AF） relaying with channel estimation error, an energy efficiency enhancement scheme is proposed in this work. Firstly, through the analysis of two-way AF relaying mode with channel estimation error, the resultant instantaneous SNRs at end nodes is obtained. Then, by using a high SNR approximation, outage possibility is acquired and its simple closed-form expression is represented. Specially, for using the energy resource more efficiently, a low-complexity power allocation and transmission mode selection policy is proposed to enhance the energy efficiency of two-way AF relay system. Finally, relay priority region is identified in which cooperative diversity energy gain can be achieved. The computer simulations are presented to verify our analytical results, indicating that the proposed policy outperforms direct transmission by an energy gain of 3 dB at the relative channel estimation error less than 0.001. The results also show that the two-way AF relaying transmission loses the two-way AF relaying transmission loses its superiority to direct transmission in terms of energy efficiency when channel estimation error reaches 0.03. 相似文献
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聚合物粘结磁体已广泛用于许多工程领域 ,因为这类磁体易于加工制造、比重低、价格也较低廉。聚合物粘结磁体是由磁粉同聚合物粘结剂在混合器或挤压机中混合后制备而成 ,混合物可用常规成型方法 (如注射成形法 )制成复杂形状的磁体元件。这种磁体的最佳性能取决于适当的选择磁粉填充物、聚合物粘结剂和填充物的分布。商用聚合物粘结磁体的应用 ,受着使用温度的限制很大 ,因此选择耐热性粘结剂和高温聚合物很重要。当前 ,选用聚Ｐ -苯撑硫化物 (ＰＰＳ)是一种理想的制造粘结磁体用的聚合物 ,因为它具有良好的热稳定性、低的粘度而且耐化学侵… 相似文献