排序方式: 共有14条查询结果,搜索用时 15 毫秒
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As evidence for his conjecture in birational log geometry, Kawamata constructed a family of derived equivalences between toric
orbifolds. In a previous paper, the authors showed that the derived category of a toric orbifold is naturally identified with
a category of polyhedrally-constructible sheaves on ℝ
n
. In this paper we investigate and reprove some of Kawamata’s results from this perspective. 相似文献
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冲击法测量是以冲击电流计为基本仪器0测量方法.冲击电流计是用来测量短时间内m冲电流所迁移的微弱电量,它可用于测量高阻电容、磁感应强度、磁性材料的特性等方面,8高校物理实验中占有重要的地位.而在这一乡实验中,冲击电流计和换向开关是不可少的计器设备.目前普遍使用的换向开关都是双刀刃掷开关,它的工作过程是先将电路断开,然后迅速接通.换向开关从开到闭,电流由一了。变为十人,有一个暂短的时间间隔.在这个时间旧隔里,电路发生了什么变化,这个时间间隔有多长,对测量带来多大的误差,如何改进?下面以冲击电流计测螺线… 相似文献
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HOU Bang-Pin WANG Shun-Jin WANG Gang SUN Wei-Li 《理论物理通讯》2007,48(2):232-242
When two identical QED cavities driven by the coherent fields are located in a uniform environment, in addition to dissipation, there appears an indirect coupling between the two cavities induced by the background fields. We investigate the effects of the coherent fields, the dissipation as well as the incoherent coupling on the following dynamical properties of the system: photon transfer, reversible decoherence, and quantum state transfer, etc. We find that the photons in the cavities do not leak completely into the environment due to the collective coupling between the cavities and the enviroment, and the photons are transferred irreversibly from the cavity with more photons to the cavity with less ones due to the incoherent coupling so that they are equally distributed among the two cavities. The coherent field pumping on the two cavities increases the mean photons, complements the revived magnitude of the reversible decoherence, but hinders the quantum state transfer between the two cavities. The above phenomena may find applications in quantum communication and other basic fields. 相似文献
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六通换向阀是一种重要的流动换向设备,用整体设计的六通换向阀替代传统的多阀控制系统,完成在主、备用动力设备间的转换.有效提高了整个系统的安全性。针对六通换向阀的特性,设计建造了六通换向阀性能测试系统,着重介绍了该测试系统的结构组成、测试方法、及主要功能。在此基础上,选择32#汽轮机油为工作介质,对80JH-33和40JH-33两种口径的六通换向阀进行了各种工况下的阻力特性实验及稳定性和可靠性实验。实验研究表明,该测试系统设计合理、功能完善、测试准确可靠.可以模拟六通换向阀实际应用的各种工作状况。还可拓展用于其它类似设备的流动性能测试与实验研究。 相似文献
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模糊聚类神经网络的死点问题 总被引:1,自引:0,他引:1
提出一种由模糊逻辑神经元网络实现的聚类分析方法,采用了竞争学习作为网络学习算法,它克服了一般竞争学习算法所固有的死点问题,使得聚类分析中始点的选取可以有更大的随意性,这在具体的应用中是很有用的.文中列举了一些有典型意义的实验,充分证实了这种方法的有效性. 相似文献
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曲柄摇杆机构是典型的平面四杆体机构,当曲柄为从动件时,存在曲柄与连杆共线的歧运动位(卡位或死点),难以实现准确的程序化研究.取曲柄为主动件,对矢量投影方程组多次求导和对角速度多次求导获得了相同的从动件位置角高阶导数.取摇杆为主动件,基于L’Hopital法则、导数乘法法则、链式求导法则和矢量方程图解法,获得了0/0型不定式的卡位运动学参数,并导出了计算公式,从而为准确的运动学程序化仿真打下了基础.算例表明,矢量投影方程组的求导与求解顺序不影响最终结果;在卡位,从动曲柄保持运动的连续性,没有冲击. 相似文献