EXTENSION OF RANGE IN RADIAL ORDER IN DETECTION AND MODE CLASSIFICATION OF SOLAR LOW-DEGREE GRAVITY MODES

The 1979 differential radius observations of the Sun have been reexamined for additional evidence of gravity modes (g-modes) beyond that reported by Hill and to classify the modes for which evidence has been obtained. The basic criteria employed in the mode detection and classification procedure are extensions of the criteria introduced by Hill. The properties of the 31 multiplets classified by Hill are used as the starting point in the work reported here. Statistically significant evidence of additional g-modes has been found and the number of classified multiplets is extended from 31 to 53. The degrees and radial orders of the 53 multiplets are respectively l=1, n=47,…, 7; l=2, n=6,…, 13, 15 and 16; l=3, n=7,…, 20; l=4, n=7,…, 20; and l=5, n=16,…, 26. The m=0 eigenfrequencies are measured with an accuracy of ≈0.02 μHz and the multiplet structure linear in angular order m is measured with an accuracy of ≈0.01 μHz.

提高电流源性能的JFET级联技术

很多工艺控制传感器（如热敏电阻器和应变桥）都需要精确的偏置电流。增加一只电流设置电阻器R1后，电压基准电路IC1就可以构成一个恒定和精确的电流源（图1）。但是，该电流源的误差与R1和IC1的精度有关，并影响着测量精度和分辨率。虽然我们可以采用精度高于大多数常用电压基准IC1的高精度电阻器，但电压基准的误差左右了该电流源的精度。制造商会尽力减小电压基准的温度灵敏度和输出电压误差．但对电源变动的敏感性仍可影响到它的精度，尤其是对于必须工作在供电电压范围很宽的工艺控制应用场合。

有效控制白光LED电流的开关稳压器

无数年前．制造商们还将自己白光LED而不是暗淡LED的最大正向额定电流设定为20mA。今天的白光LED可以提供更高的亮度．因此必须工作在更高的偏置电流下。在接近LED最大额定值的大电流工作情况下仍要保持对LED偏置点的控制．就需要一种新的方法。