...用例图与表格形式的活动图 5. 摘要 什么是用例图(use case diagram)? 有两种UML建模类型。它们是结构化行为建模。结构化建模描述系统的静态特性,而行为建模描述系统的动态特性。用例图是一个行为图。 单个用例表示系统的高...
...TEM)或扫描电子显微镜(SEM)中进行这个实验。这些仪器使用加速电子束(由静电势加速)。 图02:电子衍射图 晶体固体具有周期性的原子结构。这种周期性结构起到了衍射光栅的作用(将电子束分成几个方向不同的光束)。...
... I connect a high-gain omni-directional antenna like the one shown in this diagram to the AP. So assume that the original AP’s Wi-Fi signal radius is 250 meters, but by using the high-gain antenna, the radius become 1,000 meters. At 1,000 meters away from the AP and using a normal laptop (without...
...指出,T-Mobile之所以没有得到iPhone,部分原因是它独特地使用了AWS频谱,但考虑到芯片组的发展速度,未来版本的iPhone始终有可能支持该频谱。Humm的首席技术官Neville Ray在接受CNET的采访时直截了当地说:“下一个芯片组将支持AWS...
...低价格,例如日线图或1小时图MA=指数移动平均值 如何计算光线指数 计算所用时间段的13期均线。例如,如果使用日线图,则根据过去13天计算均线。 找到一个时期的高价并从中减去13个时期的均线,得到牛市的力量值。...
...tor. Two vectors that have the same length and direction are equal. In the diagram below, . 如何找到向量的分量 若要在给定方向上找到向量的分量,请画一条与所需方向平行的线,穿过向量的“尾”端。然后,从向量的“鼻尖”上画一条垂直线到...
...deliberately angles an aircraft to maintain a circular path. The free body diagram for both cases look similar, so I will use just one diagram to find the centripetal force in both cases. The only difference is that the force named for the car is the reaction force between the car’s tyres and t...
...在较低的电压比正常二极管。 Image Courtesy “The circuit diagram symbol for a diode.” by Omegatron (Own work) [CC BY-SA 3.0], via Wikimedia Comm*** “Current vs voltage for a semiconductor diode rectifier” by User:Hldsc(Own work) [CC BY-SA 4.0], via Wikimedia Comm*** “The ci...
...。下图显示光线通过双凸透镜(左)和双凹透镜(右)时如何折射。 Different types of lenses: the biconvex lens on the left converges rays of light passing through it while the biconcave lens on the right diverges rays of light passing through it. 由透镜形成的图像的...
...示波,我们可以如下描述反射: Law of Reflection In the above diagram, the wave approaches from the top, so the line PO represents the incident ray. The normal is a line drawn perpendicular to the surface, through the point where the ray strikes the boundary. The angle is called the...