A probable crouching theropod dinosaur tracefrom the Tuchengzi Formation in Chichengarea,Hebei Province,China

A probable theropod dinosaur crouching trace and associated tracks from the Tuchengzi (Houcheng) Formation of Siliang Mountain, Chicheng County, Hebei Province, China are the largest theropod tracks currently known from the formation. Although the crouching trace lacks manus and tail marks, the traces are interpreted as made by a crouching theropod because they include a left metatarsal impression and associated ischial, and possibly pubic, callosity traces. This represents the third known example of an asymmetric crouching position adopted by a theropod.Key words： crouching theropod trace;Therangospodus isp.;cf. Megalosauripus isp.;Tuchengzi Formation;Jurassic-Cretaceous boundary     

The timing behavior of magnetar Swift J1822.3—1606： timing noise or a decreasing period derivative？

The different timing results of the magnetar Swift J1822.3—1606 are analyzed and understood theoretically.It is noted that different timing solutions are caused not only by timing noise,but also because the period derivative is decreasing after the outburst.Both the decreasing period derivative and the large timing noise may originate from wind braking associated with the magnetar.Future timing of Swift J1822.3—1606 will help clarify whether or not its period derivative is decreasing with time.     

A Method to Calculate Inclination Function with Jacobi Polynomials

In this paper, a method to calculate the inclination function with Jacobi polynomials is studied, the formulation of this method is very simple, it needs not to concern about whether k and l have the same parity, and to calcu- late the non-integral factorials, nor to concern about the conversion between the case of k < 0 and the case of k ≥ 0, and the recurrent formula can be the stan- dard recurrent formula for Jacobi polynomials. In addition, its computational accuracy and applicable order-numbers are equivalent to those of the Gooding method, but its calculating time is shorter than that of the Gooding method for 9%.     

An Automatic Method for Detecting Transients and Variable Sources in AST3 Survey Based on Image Subtraction and Random Forest

AST3-2 (the second Antarctic Survey Telescope) is located in Antarctic Dome A, the loftiest ice dome on the Antarctic Plateau. It produces a huge amount of observational data which require a more efficient data reduction program to be developed. Also the data transmission in Antarctica is much difficult, thus it is necessary to perform data reduction and detect variable and transient sources remotely and automatically in Antarctica, but this attempt is restricted by the unsatisfactory performance of the low power consumption computer in Antarctica. For realizing this purpose, to develop a new method based on the existing image subtraction method and random forest algorithm, taking the AST3-2 2016 dataset as the test sample, becomes an alternative choice. This method performs image subtraction on the dataset, then applies the principle component analysis to extract the features of residual images. Random forest is used as a machine learning classifier, and in the test a recall rate of 97% is resulted for the positive sample. Our work has verified the feasibility and accuracy of this method, and finally found out a batch of candidates for variable stars in the AST3-2 2016 dataset.     

相律的应用:蒸发结晶过程自由度

在连续原理和浓度限制条件的基础上,分析了卤水蒸发过程的自由度,提出了“蒸发结晶过程自由度”这一概念。发现蒸发结晶过程自由度在整个过程中不是1便是0,在1和0之间交替变化,与选择的组分数和析出固相数目无关。蒸发结晶过程自由度为1,物理意义是在不引起新相产生旧相不消失的前提下过程连续地变化(水分的连续蒸失),几何意义是指在适当的坐标系中的一条线,一条直线或曲线;0的物理意义是指新相的产生和旧相的即将消失或者前一段的连续变化过渡到后一段的连续变化,几何意义是指一点,两蒸发阶段的交点或者过程的终点。简单地讨论了过程的单向性和连续件。