example.msim

I want to get an adjustable parameter in maplesim. For example, here is a pulse voltage source, i  want to make its amplitude controlled by another voltage output (doesn't exist in this .msim).

ac-dc-dc1.msim

When i click off the "Plot events", the figure of Probe2 is pretty different comparing with "Plot events" is turned on. Here is my assumption: the simulation duration is 500 seconds and the plot points are 2000. Considering the frequency of sine current is 40HZ, many points cannot be ploted in the figure. So it is not a big deal for curve like Probe1 and Probe5 because  they tend to be a constant and Probe2 just reflect the tendency.

piezoelectric_equivalent_with_ac-dc_(1).msim

I try to build a piezoelectric equivalent circuit (a sine current source, a capacitor and a resistor), but it doesn't act as a voltage source. I also try to change the forward voltage of the ideal diode in full-bridge rectifier and find that the output voltage of piezoelectric equivalent circuit cannot exceed forward voltage.

By the way, the parameters of piezoelectric equivalent circuit are well set according to a paper.

Could you give me some advice?

v2i2v_circuit.msim

I try to design a circuit to make a voltage-current-voltage translation. In my assumption, probe1.v is equal to probe2.v and it will generate a current(probe2.v / R4) through NMOS. The NMOS acts as a closed switch. Probe3.v is equal to CV3 and i can get "Probe4.v = CV1 + CV3". However, when the circuit operates, probe3.v isn't equal to CV3 and probe1.v isn't equal to probe2.v. I have tried to rise the differential input resistance and differential amplifier to make the Uin+ close to Uin- in op amp, but it doesn"t work effectively.
In addition, the closed resisitance of NMOS is also taken into consideration and i try to make it pretty below Kohm.

Could you help me fix the problem? 

battery_charging_circuit.msim

I am trying to design a charge circuit for Li battery, but i don't think it is a good idea to discharge the battery by a resistor or a cuurent source. So, how can i set the parameters to make the battery discharged initially?