Recent content by Riscilla

Agreed. However, I am talking about using the internet to support the R&D job itself. There are times when you need to search for the information your job demands, and the internet is the best and fastest source for most of those information. My opinion is, the companies should find another way...

Hi guys, I wonder in the R&D department of companies like Google, IBM, Sony, ... Do they allow their employees to use the internet when working? Some people argue that: because of the confidential requirements, these companies often prohibit internet in their R&D department. However, I...

Hi everybody, I want to buy a 3kW induction cooktop. The one I intend to buy requires a power source at 220V/60Hz. However, in my country, the main power is 220V/50Hz. Does this difference in frequency cause any incompatible problems? Can I use the induction cooktop in my country? Thanks.

If it is the answer, then there must be a way to prove it, otherwise the question is meaningless. I don't know. This is not an excercise from the books I have. You guys have got any other ideas?

Hi PeterO, Thank you for your answer. I could find a combination satisfying the requirement myself. The difficult part of the problem lies in finding the combination having the smallest possible number of resistors. regards,

Hi vkash, Thank you for your answer but the value of the resistors is 12 Ohm, not 6 Ohm. Moreover, how can you prove that the combination you suggested has the smallest possible number of resistors?

Hi guys, I have an interesting and difficult problem as follow: Find the smallest number of 12 Ohm resistors (and of course how to connect them) to achieve an equivalent resistor of 7.5 Ohm? I have worked on this problem for many hours but cannot find the answer yet. Somebody can...

Hi friends, I have a question regarding the use of filters in closed-loop control systems. Very often in a system like that there is noise from the sensor, and we have to put a filter after the sensor to eliminate the noise. However, all filters produce a phase shift as well as an amplitude...

Thank you for your answers. So the pipe connecting the indoor and outdoor units is of no use in this mode? I guess that this pipe is only used to transfer the coolant gas, and hence is only used in the cool mode, am I correct? I don't know, because in the remote control, the modes are...

Hi friends, My air conditioner is a split one (it has 2 parts: one inside the house and the other outside). It has 4 modes of operation: cool, fan, and 2 other modes. My question is that what does the machine really do in the fan mode? I wonder whether it just serves as a normal fan...

Thank you for your helpful suggestions. I want the chimney to be as tall as possible. If I were to use that doubled-layer chimney, how long could the chimney be? It might be difficult to give an exact answer to this question, therefore I think an approximate one will help.

Thank you all. Now the problem already becomes more clear to me. Well, I intend to install a small fan inside the chimney to increase the drawing force. How do you think about that?

Thank you for your answers, I also guess that if there is a wind then the chimney might not work effectively. But in case there is no wind, how well does the chimney perform? As far as I know, if the chimney is high enough, there will be a difference in pressure between its 2 ends: At the...

Hi friends, We all know that chimneys are used to suck up smoke from a house's fireplace, in order for the smoke not to spread all over the house. But I wonder if I can use a pipe with a wide open end to create a similar effect outside the house? The following picture demonstrates what I mean...

Thank you all for your detailed answers. Now I already understand the problem. :) Regards, Riscilla.