Recent content by chingkui

I suppose the ##A## matrix you use is a 3x2. And yes, A maps a circle to a ellipse, but I will try to clarify the process of how a circle is mapped to the ellipse geometrically using the SVD. So, a circle in ##R^2## is the set of unit vector, each one get mapped to another vector in ##R^3##. So...

Hi josh, You mentioned you read about unit sphere and SVD, can you explain geometrically what you understand/don't understand?

No, it isn't. To see why it is not, you have to go through the derivation of KF, and the associated error propagation. One key properties of KF is that it is an unbiased state estimator. Your proposed state propagation model is biased by exactly the missing measurement term which has non-zero...

Not sure if I understand what you said correctly. But if you mean using a wrong prediction model in KF, and then rely on the measurement updates to correct the state, I am not very optimistic that it will work. If the only reliable information is the measurement update at each instant, why use a...

The system you refer to has 1 rotation DOF, the current state (angle) is the sum of the previous state and the change of rotation angle the most recent interval, hence x(k+1) = x(k) + w*dt is the system dynamics. If you instead write the dynamics equation as gyro input free, you are modeling a...

In designing a KF, first you have to write down exactly what you are trying to estimate here (the state x), and then write down the dynamic equations x(k+1) = Fx(k) + n(t), by writing down the dynamics, you probably would see if the model needs the sensor input. From your description, I am not...

If you only have one single gyro, there is no way you can estimate the attitude unless your system is highly constrained with two components locked. You need 3 gyros in general. And what other sensors are available? Even if you have 3 gyros, KF is useless by itself if you have no other...

I know this is true under thermal equilibrium, but I am not sure why. Why can't the Fermi level be a function of position relative to the pn-junction? How does that follow from thermodynamics/statistical mechanics?

it is very hard for anyone to give you advice if you can't say what you find interesting.

If good salary is the reason, wouldn't it be very easy? Go job hunting, and if you get multiple offers, pick the one with the highest salary?

I am working on a project about pollution emission, but I am not a chemist. I am seeing the units ppmC, ppmC3 and ppmC6 almost everyday, and I have trouble understanding what they stand for. The only definition I get is "Parts per million hydrocarbon concentration expressed as methane (for...

Not all jobs in the defense industry require security clearance. However, most jobs would require US citizenship or at least permanent residence, which I believe has to do with export control compliance. If you are not a US person (US citizen or permanent residence), you will be competing for...

From what I have read so far, the vapor pressure of a liquid is temperature dependent while it is independent of the atmospheric pressure. I am not sure why atmospheric pressure would have no effect of the vapor pressure though. For example, if a highly volatile liquid is placed in a sealed...

I agree that there is definitely no reason not to apply. And renewal of the DOE fellowship is not that hard, at least from my experience. I would advise you to spend a bit more time in putting together a good application though, think about how your research plan relate to the fellowship...

I am thinking about this problem that come up in some of my work, I think this has been solved before, though I am not aware where I could find the solution. Here is the question: Suppose a graph has say 20 nodes with no edge initially, and at each instance, 4 (different) nodes are randomly...