试题学习

2017-09-17

1.Please describle open-loop and closed-loop control system.

2.There is one DC Motor control system. here are the signals :feedback encoder signal S(displacement), time T, speed V. The DC motor is to 　be  changing the average voltage of the motor, which is done via changing PWM duty cycle. To control the speed of the DC motor, please 

　give your scheme, work out your PID control model and give expianations of each signal in your scheme(contorl targe, controlled object 　       and feedback signal).

3.There are 5 sample values from a 8 bit ADC channel here :154 , 156, 157, 159, 152, please give the solution(eg. algorithms by equations)

　on how to reduce the noise using the following ways.

　　1)The first-order low-pass filter (weight coefficient for sample :130/256).

　　2)The Average filter.

　　3)The Median filter(monitor window 5).

4.Write a function to insert an element into a double linked list.

5.Write a function to find a matching element inside  a sorted array.

6.Adding to pointer that points to an array will______.

　　A. cause an error

　　B.increase the value of the element that the pointer is pointing to

　　C.cause the pointer to point to the next element in the array

　　D.none of the above

7.About the concept of reentrancy, which of the following statement is NOT correct ?______

　　A.it is useful, memory-saving technique for multi-programmed time sharing systems.

　　B.A reentrant procedure is one in which multiple users can share a single copy of a program during the same period.

　　C.it executes the code in the permanent part, but has its own copy of local variables/parameters.

　　D.A reetrant procedure cannot be interrupted.