随鱼下水

某日下午,天阴无风。某塘周围,数十名垂钓者因鱼不贪钩,均安然就坐。忽一漂连动横移,B钓友及时举竿,顿时线绷竿弯,同塘钓友皆举目相望。遛了几圈,一尾一千克左右的鲤鱼被牵至岸边,可惜未带抄网。

饲用液体鱼蛋白

饲养畜、禽、鱼,需添加蛋白饲料。鱼粉是营养完全的高蛋白饲料。然而生产鱼粉需整套设备,工艺复杂。能否找到一种鱼粉的代用品,扬鱼粉之长而又避其短呢?原来早在本世纪二十至三十年代,芬兰、瑞典就开始研制、开辟一种新的蛋白源——液体鱼蛋白(fish silage)。五十至七十年代,北欧的丹麦、挪威、波兰、英国,东南亚的斯里兰卡、印度、印尼、泰国、马来西亚、菲律宾以及澳大利亚、新西兰和香港地区也相继生产、应用。

Modeling and simulation of torpedo acoustic homing trajectory with multiple targets

The characteristics of a torpedo＇s acoustic homing trajectory with multiple targets were studied. The differential equations of torpedo motion were presented based on hydrodynamics. The Fourth order Runge-Kutta method was used to solve these equations. Derived from sonar equations and Snell＇ s law, a simple virtual underwater acoustic environment was established for simulating the torpedo homing process. The Newton iteration method was used to calculate homing range and ray tracing was approximated by pieccwise line, which takes into consideration distortions cause by temperature, pressure, and salinity in a given sea area. The influence of some acoustic warfare equipment disturb the torpedo homing process in certain circumstances, including decoys and jammers, was alsotaken into account in simulations. Relative target identification logic and homing control laws were presented. Equal consideration during research was given to the requirements of rcal-timeactivity as well as accuracy. Finally, a practical torpedo homing trajectory simulation program was developed and applied to certain projects.