We know from Noether’s theorem that there is a conserved charge for every continuous symmetry. In General Relativity, Killing vectors describe the spacetime symmetries and to each such Killing vector field, we can as...We know from Noether’s theorem that there is a conserved charge for every continuous symmetry. In General Relativity, Killing vectors describe the spacetime symmetries and to each such Killing vector field, we can associate conserved charge through stress-energy tensor of matter which is mentioned in the article. In this article, I show that under simple set of canonical transformation of most general class of Bogoliubov transformation between creation, annihilation operators, those charges associated with spacetime symmetries are broken. To do that, I look at stress-energy tensor of real scalar field theory (as an example) in curved spacetime and show how it changes under simple canonical transformation which is enough to justify our claim. Since doing Bogoliubov transformation is equivalent to coordinate transformation which according to Einstein’s equivalence principle is equivalent to turn on effect of gravity, therefore, we can say that under the effect of gravity those charges are broken.展开更多
基于工频电源驱动时扩展 Park 矢量方法诊断笼型异步电机转子断条故障的有效性,研究了在变频电源供电情况下该方法的诊断有效性。对断条故障电机变频电流进行了实测、分析和对比,结果表明:当采用变频电源供电时,传统的单相电流频谱分析...基于工频电源驱动时扩展 Park 矢量方法诊断笼型异步电机转子断条故障的有效性,研究了在变频电源供电情况下该方法的诊断有效性。对断条故障电机变频电流进行了实测、分析和对比,结果表明:当采用变频电源供电时,传统的单相电流频谱分析方法无法正确诊断转子断条故障,而扩展 Park 矢量方法仍然具有良好的诊断准确性和适用性。展开更多
文摘We know from Noether’s theorem that there is a conserved charge for every continuous symmetry. In General Relativity, Killing vectors describe the spacetime symmetries and to each such Killing vector field, we can associate conserved charge through stress-energy tensor of matter which is mentioned in the article. In this article, I show that under simple set of canonical transformation of most general class of Bogoliubov transformation between creation, annihilation operators, those charges associated with spacetime symmetries are broken. To do that, I look at stress-energy tensor of real scalar field theory (as an example) in curved spacetime and show how it changes under simple canonical transformation which is enough to justify our claim. Since doing Bogoliubov transformation is equivalent to coordinate transformation which according to Einstein’s equivalence principle is equivalent to turn on effect of gravity, therefore, we can say that under the effect of gravity those charges are broken.
文摘基于工频电源驱动时扩展 Park 矢量方法诊断笼型异步电机转子断条故障的有效性,研究了在变频电源供电情况下该方法的诊断有效性。对断条故障电机变频电流进行了实测、分析和对比,结果表明:当采用变频电源供电时,传统的单相电流频谱分析方法无法正确诊断转子断条故障,而扩展 Park 矢量方法仍然具有良好的诊断准确性和适用性。
