资讯

目前,京城已经形成了一个比较完整的私教体系,私教的服务质量现在已成为健身会馆比拼的重要指标之一,因此虽然私教的数量在增加,依然供不应求。记者通过一些大型健身机构了解到,一位私教每天授课4至7个小时,一个月以20天计算,平均下来每人就在90至110课时左右。按业内人士提供的4比6的分配比例。

Stochastic Optimal Control of First-Passage Failure for Rectangular Thin Plate Vibration Model under Gaussian White-Noise Excitations

A rectangular thin plate vibration model subjected to inplane stochastic excitation is simplified to a quasinonintegrable Hamiltonian system with two degrees of freedom. Subsequently a one-dimensional Ito stochastic differential equation for the system is obtained by applying the stochastic averaging method for quasi-nonintegrable Hamiltonian systems. The conditional reliability function and conditional probability density are both gained by solving the backward Kolmogorov equation numerically. Finally, a stochastic optimal control model is proposed and solved. The numerical results show the effectiveness of this method.

“笑脸”绵羊

英国每日邮报报道,英国莱斯特郡、德文郡、佩思郡等地五个农场数百只绵羊身上先后出现了一张张神秘的"笑脸"。这些"笑脸"的眼睛是螺旋形的,嘴巴长长。这一现象让人困惑不解,在网络上引发热议。有人将之归之于一种超自然的力量,有人干脆将其与外星人联系起来。这些出现在绵羊身上的图案皆为黑色,在白色的羊毛上格外显眼,样子看上去像诡异的"笑脸"。这些图案最先被发现于爱尔兰东部莱斯特郡梅尔顿莫布雷的一座牧场,当时约有20只绵羊身上被画上了标记。随后。