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# Observer - Science topic

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Questions related to Observer

I want to use Kalman filter to estimate battery parameter and observer for state estimation together (SOC)

The measurement problem in quantum physics shows that an observer can manipulate the outcome of experiments studying the behaviour of light (Young, 1802 double-slit experiments) and control whether light will manifest as a particle or a wave (Bohm, 1952; Cho, 2017; Kocsis et al., 2011). This shows that consciousness may be compatible with light or may be able to communicate with light (Kroeker, 2019). I was wondering if consciousness could be quantized if the observer effect experiments were reversed engineered to measure the behaviour of consciousness, rather than the behaviour of light?

Discuss...

Why isn't the velocity of light given by the speed of the observer plus the speed of the light (addition of velocities)?

Why does the light ray slow down and compensate or speed up and compensate for your motion, so that it is always travels at the speed of light? notwithstanding your motion?

In short, what is the mechanism that means the velocity of light always remains the same, irrespective of the motion of the torch issuing the light ray?

Is the -apparent- progress of light, along the left and right-hand limbs, different for different observers?-- in the standard arrangement for the Relativity of Simultaneity, as suggested by the animation in "apparent pogress.docx" .

And if so, just considering the right-hand limb, why can't we place an event E, such that, for one observer the light has already reached and enveloped it, while for another observer, the light has yet to reach it, -- as viewed by these two different observers?

Is the -apparent- progress of light, along the left and right-hand limbs, different for different observers?-- in the standard arrangement for the Relativity of Simultaneity, as suggested by the animation in "apparent pogress.docx" .

And if so, just considering the right-hand limb, why can't we place an event E, such that, for one observer the light has already reached and enveloped it, while for another observer, the light has yet to reach it, -- as viewed by these two different observers?

If we are to correct the long-range action of the global inertial frame of Newtonian mechanics, shouldn't we make it the close action of the relative velocity of light?

Preprint Spontaneous invariant generation

The Hawking temperature $T_h$ is proportional to the surface gravity $\varkappa$ which, in spherical-symmetric case, one calculates on the Killing horizon. This temperature is very small but where? at infinity? Then if we use the formula $T\sqrt{g_{00}}=const$ then, one obtains infinity temperatures near the event horizon. Help me with this question please. I thought that one measures $T_h$ near the event horizon and the temperature near the horizon is small. Or my opponents are right and this temperature is measured in infinity?

I am working on observer based active fault tolerant control( Fault detection and isolation (FDI) scheme) for handling sensor faults in a system. The system has also a dynamic disturbance component also which is difficult to have a proper observer design to design the FDI of the FTC scheme. I would like to know the effective methods to handle such situations with observer based FTC schemes. How to handle the issues of disturbance modelling and threshold selection in such schemes? Also what could be the limitations for such schemes?

Apropos: the Andromeda paradox.

Can anyone tell me which of the below, if any, describe the arrangement in the Andromeda paradox?

For event 1 I am assuming this to be 'the decision' to launch the fleet, and for event 2 I am assuming this to be a later event signifying that the 'fleet is deployed'. Event 2 occurs after event 1, of course, for the Aliens.

According to the paradox, the light from these events reaches the observers in such a way that event 1 is seen first by one observer, and while event 2 is seen first by the other observer?

If that is what the paradox is saying, can anyone explain (ideally with an animation or a picture) how this happens?

Apropos: the Andromeda paradox.

Can anyone tell me which of the below, if any, describe the arrangement in the Andromeda paradox?

For event 1 I am assuming this to be 'the decision' to launch the fleet, and for event 2 I am assuming this to be a later event signifying that the 'fleet is deployed'. Event 2 occurs after event 1, of course, for the Aliens.

According to the paradox, the light from these events reaches the observers in such a way that event 1 is seen first by one observer, and while event 2 is seen first by the other observer?

If that is what the paradox is saying, can anyone explain (ideally with an animation or a picture) how this happens?

How to calculate the gain matrix of Luenberger /state observer?and also what is the role of eigen values during the mathematical modeling?

The current system have 2 input and 2 controllable states. The system is observable.

We have developed an arrangement in the Relativity of Simultaneity framework that must be wrong, as we cannot have a situation where two events, situated at the same place (event E, and an arrival of light event) are switched in time-order, for two different observers moving uniformly (or non-uniformly) relative to these events.

Is it that the placement of event E in animation Figure 4 is somehow not allowed?

Is it that it is not always possible to make two events separated in space simultaneous? by suitable choice of the motion of the observer? (cf. Einstein's train gedenken experiment.)

If anyone can pinpoint the error, much appreciated.

Vide : "Short Precis" below for desciption of new arrangement and animations.

See also question:

There is this paradox in quantum theory involving the measurement of entangled particles. Say separated observers (even widely separated), A and B, measure the spins of an entangled two-photon state whose total spin is zero. If A gets spin +1, B must get spin -1 and vice versa. But what if there are two observers, M and N, moving such that observer M sees A measure first but observer N sees B measure first. In particular say M is abreast of A when A measures and N is abreast of B when B measures. It would seem that for M, A's measurement would determine what B's should be. But, it would also seem that for N, B's measurement would determine what A's would be. By symmetry, it would seem that neither measurement should be primary but neither secondary. Note that A and B do not have to be in the rest frame of the device that issued the entangled photons. Has any experiment been done to test this paradox? I'm pretty sure the experiment would be very difficult -- maybe not even possible?

I want to build a Bayesian observer model of an interceptor that uses information of (prey) location and speed. Any suggestions of where to start? Papers, MATLAB code, etc.

In the following figures, the adaptive gain (c_i and rho_i) selection is also having problem??

Hello everyone,

How I can program a Lundberg state space observer using the Simulink block "Matlab function" and display the result on a scope ?

In Einstein’s 1095 paper 'On the Electrodynamics of Moving Bodies' he presents two clocks: Clock A is moving in a linear fashion relative to clock B, and hence Clock A would experience a dilation in time, ticking slower through each second, despite before beginning its horizontal translation it being synchronized with same.

Hence if time can bend for a moving observer (due to the perspective of a fixed observer watching them) Einstein's first postulate of relativity (that all frames of reference are equally valid) tells us that it can also bend for the fixed observer (from the perspective of the moving observer.) This is mutual time-dilation. It is a perceived relative phenomenon (depending on the perspective of the observer in question), however the principles from which it arises are psychological in nature; not physical, yet they are regarded as an accurate representation of the mechanics of the physical world by the bulk of the scientific community.

Perspective does not equate to reality. Time moves mountains and turns grasslands into forests; how can it be touched? Let alone bent.

So the question as it has remained for over a century still stands:

Which clock is moving faster? As it is a physical impossibility that both clocks are moving faster and slower than each other. Mutually-exclusive simultaneous events can only occur in the mind.

Sensorless Control of a Doubly Fed Induction Machine Based

on an Extended Kalman Filter

Improved Sensorless Control of Doubly Fed Induction Motor

Drive Based on Full Order Extended Kalman Filter Observer

Time seems to be related to the continuous destruction of the wave function ψ between an observer and an abstract objective reality. So space and time is a subjective coordination for the past of one of the many parallel universes, but on the contrary the future must contains all future dynamic universes. Is it an objectively false?

I am trying to convert the spectral radiance values of an HSI acquired from the E0-1 Hyperion Sensor into reflectance. However, I couldn't continue the calculation without the Mean Solar Exo-atmospheric Irradiance values.

According to classical electrodynamics theory, an accelerating charged particle emits an electromagnetic radiation. Unruh on the other hand found that an accelerating observer (charge) will find itself immersed in a black body radiation from the vacuum. How the de Broglie wave interacts with the electromagnetic radiation created by the particle? Is there a relation between wavelength and acceleration for an accelerated charged particle? Does the black hole evaporate completely or end in a finite mass (e.g., planck mass)?

I've been told:

“As measured by proper time, a radially falling traveler quickly reaches and crosses the critical radius of a black hole. The reality that the traveler quickly reaches the critical radius appears to the distant observer to take an inﬁnite amount of time because of the propagation of light.”

But let’s test this with a thought experiment:

Put a reﬂector on the back of the traveler as he freefalls towards the event horizon of a black hole. Have a distant observer periodically shine a light beam at the traveler. Use the Schwarzschild metric to calculate the radial location at which the faster moving light beam will overtake the slower moving traveler and reﬂect back to indicate the location of the traveler to the distant observer. No matter how much of a head start the traveler has before the light is turned on, according to the Schwarzschild metric the light will always overtake the traveler before the event horizon is reached. Let the distant observer continue to shine light beams at the traveler until the distant observer observes that the black hole evaporates because of Hawking radiation. Granted, this will take a long time. But the entire time, the reflected light will continue to reflect back from the traveler showing that the traveler fails to reach the event horizon before the black hole evaporates.

How can this be?

- Is there any statistical method
- Is there any physical /technical way to do that

Something which has always bugged me about the standard model is how can we approximate the age of the universe, when at the beginning, the incredible density would dilate time to the point to where proper time since would approach infinity? Which reference frame are we talking about? Further, if it is truly space which is expanding, and not massive particles moving further away from each other, an observer frame outside the curvature would not exist in the physical universe at the time in question. Another question I have is how might the Planck length be affected in such a dramatically curved space-time?

I would like to add some visual example to illustrate the different types of participant observation (complete observer, observer as participant, participant as observer, and complete participant). Any suggestion is welcome.

Thank you,

Isabella

State observers are very frequently used to estimate the states of the system to design controllers. The question is what are the disadvantages/limitations of using observers? Does output feedback control solve those problems? If not, then what are other methods to solve issues with observers?

if I want to add a disturbance observer to an existing feedback controller (i have design a controller C(s); suppose it is a double loop PI controller fo an IBC converter. ) what would I do get this done ? and How does this affect the stability of the closed-loop system?

The Nyquist-Shannon theorem provides an upper bound for the sampling period when designing a Kalman filter. Leaving apart the computational cost, are there any other reasons, e.g., noise-related issues, to set a lower bound for the sampling period? And, if so, is there an optimal value between these bounds?

can we used observer based controller to commercial water heater plant in order to make a correct decision of the output and simultaneously to observe the system

I have designed the mathematical model of the plant with nonlinear hystersis function f(x1) and is validated using simulation. Now I want to design the nonlinear observer to esttimate the speed (x2). Not that I have also modeled the nonlinear function in the model.

My state space model of the plant is

x1_dot = x2

x2_dot = q*x1 + c*x2 + f(x1) + u

Please suggest suitable observer to estimate the angular speed x2.

x1 is the angular position of the plant.

It is known in a input / output feedback linearization control that in a closed loop the physical state of the system is transformed into a linear mathematical state, which we have to stabilize by a linear auxiliary control, this linear mathematical state must be obtained, either by successive derivations of its outputs which is not recommended in case of implementation, or by a Luenberger observer.

In this question we want to know how demonstrate that this stabilizing linear control of the closed loop system can be developed via the physical state estimated by a nonlinear Thau observer.

Hi

I am conducting an interobserver variability study where we have 12 raters who are going to rate samples of lesions. They will rate up to 10 variables per sample. Although the size of the population is quite limited due to the nature of the lesions, it is a bit of a headache to find a well-written method to estimate the sample size needed for this study. Several searches on the internet have overwhelmed me with many possibilities, most of them being quite complicated.

Is there any statistical method you can recommend? Any help is appreciated!

kind regards,

Roger

Our knowledge of the world begins not with matter, but with perception. There are no physical quantities independent of the observer. All physical quantities used to describe Nature refer to the observer. Moreover, different observers can take into account the same sequence of events in different ways. Consequently, each observer assumes a “stay” in his physical world, which is determined by the context of his own observations.

If mathematics and physics, which describe the surrounding reality, are effective human creations, then we must consider the relationship between human consciousness and reality. Undoubtedly, the existing unprecedented scientific and technological progress will continue. However, if there is a limit to this progress, the rate of discovery will slow down. This remark is especially important for artificial intelligence, which seeks to create a truly super intelligent machine.

I am working in speed sensor-less control of induction motor and for estimation of speed i have used sliding mode observer. Using SMO I have estimated alpha-beta axis stator current and alpha-beta axis rotor flux accurately. though I have estimated currents and rotor fluxes accurately, I can not estimated speed. Is there any one who can help me with this issue?

I have also added the images of results that i have obtained.

I am designing a flight controller for a quadrotor.

At first I am designing a nested/cascaded controller consisting of only proportional controllers K

_{p . }Now, if i tune the rate controller for 10 rad/s cross-over frequency, what should be the cross-over frequency for the angle, velocity and then the position loops. Also, what else do i need to know while designing a flight controller for practical implementation purposes?Secondly, How do we implement a own flight controller such as observer based via arducopter?

I am trying to discretize a continuous time state space model using the following code

s=tf('s');

G=1/(Iyy*(s^2))

Gs=ss(G)

Gd=c2d(Gs,0.01,'zoh');

Now, when i use this discretized model 'Discrete State-space Model' in simulink, my close loop system goes unstable. Same is happening with observer, like discretized observer is making close loop system unstable. Can someone help me here?

I am exploring the possibility of using a mixed method research design to investigate creative cognition in dance. My aim is to describe cognitive processes in choreography, according to cognitive psychological theories. For this purpose, I intend to use a mixed method research design (including observation and psychometric tests), I have, however, not come across a study that uses the participant observer method in such design. I would appreciate insights/ relevant literature.

We have several measures for a given event in our longitudinal study (e.g., Year 1). Some are surveys we are sending to participants and their families, while others will be entered by study staff. For the surveys, some measures should be completed by the participant, while others should be completed by a parent or observer. Other than creating separate arms for each type of respondent (which creates its own issues), is there a way to send out only a portion of the surveys to one respondent and the other portion to another, and still have them linked to the same record?

I want to know whether a luenberger observer or a modified form of it be effective for estimating the states of a system of the following forms:

**1. x_dot = f(x,u,d); y = x**

**2. x_dot = f(x,u); y = x**

where

*x_dot*is the derivative of the state vector,*u*is the control input and*d*is the external disturbance input.*f*is a nonlinear function with the product of states, control inputs, and disturbances.Please give some specific suggestions regarding the observers which are best suitable for state estimation of such models.

Am I starting a discussion because I made a discovery or did I make a discovery because I started the discussion?

What if it is not that I am speaking true or false and definately it isn't about Free Will vs Determinism anymore, Why?

Because what if there aren't two sides any more but there appears to be two sides,

Can I not say that the observer and the observed are both "IN SYNC" with one another?

So could it be that it's not about whether or not the observed is because of the observer but it is about that the observer and observed seems to give rise to two contradictory notions but the fact is that both the observer and the observed exist,

So can I really say that and what does it mean if I say they are "IN SYNC"

Could it also be that mass and energy are appearances of something that exist and because of what I think is the right term to communicate my observation and because of the "IN SYNC" that I refer to, could it be that both mass and energy are there but also not really there, it just appears to be there, but what would be responsible for that appearance then?

What does it mean not literally but in understanding of what I am trying to put in words based on observation and sound reasoning of what it means to be in the "NOW" and why it is a fact that both the observer and the observer exists rather than whether or not observed exists because of observer.

But in essence,

What does it mean if I say that the observer and the observed are "IN SYNC"?

Can an alternative to Minskowski’s space-time diagram explain all this?

How the world-lines of all bodies in uniform motion have the same length in spacetime;

that bodies in relative motion have different orientations in space as well as time;

how observers with relative motion between them will each observe the other to be

moving more slowly in time;

why the speed of light is the absolute limit of speed;

that light is a constant, and for any observer, the speed of light is ~300,000 km

(or ~186,000 miles) per second, because in the continuum of spacetime,

the distance it is observed to cover in space is equal in length to one second in time.

Hi

I am working on Active Disturbance rejection control of a quadrotor, which consists of an extended state observer. Can anyone guide me about it or suggest any book/thesis that is available. I shall be grateful.

Regards

Is it theoretically possible, that after discretization by using Talyor Series Expansion, a non-observable nonlinear system will became an observable?

It was proved, that used continuous model of PMSM is non-observable (see attached). I want to know, if resulting discrete system is observable or not. Any comment appreciated. Thanks.

Dear All,

I did Nyquist plots ac impedance measurements and I found the following plot. Can anyone help me to explain the observer trend with different concentration on steel with blank?

Thanks for your help.

Regards,

B. Thanga Giri

Please suggest to me some alternative state observers which are comparatively more effective than Sliding mode observers (SMO) for handling nonlinear systems with disturbances.

Two observer evaluate the same qualitative variable; what is the best statistics descriptor to evaluate concordance? K cohen, concordance correlation coefficient, phi coefficient of pearson, other?

I try with K cohen, but despite 66/67 of concordance (98.50%) k cohen was too low (K=0.659). while with 58/67 (86.57%) of concordance k cohen was 0.730. Why?

Thanks

I've used Noldus Observer before, but can't afford it now. I'm not sure that it matters, but this is for scoring frequencies and durations of rodent behaviors within neuroscience/ethology studies using digitally recorded videos.

I'd like to have the capability of running simultaneous timers that can be independent or dependent on one another (depending on my optimizations), while also being able to tally frequencies of select behaviors/events independently. Ideally, the tallying and/or starting or stopping of timers would be tied to selected (ideally programmable) keystrokes.

Does anybody knows of a systematic monitoring methodology which is indipendet on the skill and the eyes of the observer i.e. any one that monitors will end with same result

I have implemented utkin observer for drum boiler turbine system...The estimated state converge to actual state at a different initial condition but it is not converging at arbitraty intial condition..can someone knows the reason?

I am a control engineer and also a student who is studying the doctor's degree. I am interested in the disturbance observer now, I need some information about the discrete-time implementation of the DOB . Could anyone give me some advice？Thank U very much 。

Black swan risks are described as an extreme outlier events that come as a surprise to the observer, and in hindsight, the observer rationalizes that they should have predicted it. Those risks have the maximum impact, but the minimum likelihood, and it's never easy to predict them. How can we draw the line between realistic risk scenarios and those perceived as unrealistic, but nevertheless possible ones, with catastrophic outcomes?

Hi everybody,

I'm using ebeam evaporator to deposit 20-50 nm of Cr on PMMA (950k A4). I coat PMMA on glass by spin coating at 1000 rpm then bake at 170 C in 10 min. However, I observer so many cracks on Cr layer after deposition. Could you please suggest a potential solution?

Also, the adhesive between Cr and PMMA of my sample is not good that I can easily remove the Cr layer by scotch tape. Is there any way to improve the adhesive between Cr and PMMA since I have tried Ti, Ni but it did not work.

Thank you.

recently I faced to a problem in extracting an advantageous mathematical model of a pneumatic servo positioning system which uses a normal cylinder and piston actuated with a proportional pneumatic valve, to be applicable for designing an intelligent neural network-based adaptive controller with the use of sliding mode observer for the aim of trajectory tracking with the presence of matched and unmatched uncertainties and nonlinearities and disturbances. the approach will be considered as a disturbance rejection or fault-tolerant method. But the problem is the emerging complicated high order relations specifically in modeling the proportional valve. we have the mass flow rate ''m dot'' equation which is a function of valve-generated compressed air pressure ''P1 and P2'' flows into both sides of the cylinder and the generated control signal ''u''. but the main equation for describing the whole process is based on the second law of newton which is written as "

**m(y double dot)=(P1.A1 - P2.A2) - Ff - FL- Fd**". the challenge is on the term**(P1.A1 - P2.A2)**and more specifically on how to define P1 and P2 in order to be as simple as possible and not to increase the order of the system equations. in some researches (like my recent IEEE 2018), P1 and P2 define by using thermodynamic laws and physical description. in these approaches, you may face with the derivative of P1 and P2 and so you forced to differentiate the whole equation and turns it into "**m(y third dot)=(P1dot.A1 - P2dot.A2) - Ff - FL- Fd**". in other hands in a few types of research in order to avoid the complexity and decrease the order of system equations, the term**(P1.A1 - P2.A2)**turns into a simple form of**b.f(u)**in which b is a positive constant and f(u) is a function of control signal. this form of description is a bit conservative but helps a lot in extracting a state-space and control form representation which is of necessities for designing the nonlinear controller.now the question is

**if I need a sliding mode observer thorough designing the disturbance rejection intelligent adaptive controller**, what can I do and which way is more effective? any other so far so good ideas and comments which are not mentioned in the explanation or any kind of corrections if I am wrong in any parts are all welcomed.What type of slides and cover glass you use while working on an inverted fluorescent microscope (We are about to get an Axio Observer 7)

Also it would be good to know what kind of petri dishes / microplates / flasks can be used. Can we use plastic ones or they should be glass only?

I have designed an observer based control strategy. Now I want to analyze its stability analysis. So my query is; that we must sort out the stability of the closed-loop system or we can find it for a separate section.

Hi there,

I got data of multiple observers that measured the weight of an animal (the same). It's literally just one column with categorial value for the observer and another for the measured weight. Each observer measured the animal 3 times.

One particular observer is new in the field (so has no or little experience) and I would like to test if that observer might deviate from the others in his measurements -- I would go for a one-way ANOVA here, is that correct?

And another hypothesis is that whoever measured the animal has a significant effect on the estimated weight -- how do I test for that? Isn't it both the same? It's two different questions for this research, so I am a bit confused if it's actually different tests?

Thanks a lot!

Saskia

Suppose time is proportional to entropy. Then time would be related to energy and how it distributes. Is time a kind of projection of a feature of the universe. Is it possible to conceive that our universe looked at from outside would appear to be unchanging and featureless (like a black hole) and that the inhabitants inside perceive changes that are from the outside observer’s perspective illusions?

Hi fellow reserachers,

Quick question:

I was wondering if anyone has suggestions for where to find open access datasets on observer agreement involving >= 3 observers?

An example of such a study is this one:

"Interobserver and Intraobserver Variability in Measurement of Non–Small-Cell Carcinoma Lung Lesions: Implications for Assessment of Tumor Response".

Yours sincerely

Generally when we describe motion of an object, we think of a `` point mass''and use the hypotheses of geometry to pictorially depict its trajectory as a curve. Then usual methods of calculating slope, etc. are used to define velocity, etc. This is the way, a person standing by the side of a road, will describe the motion of a moving car. However, if the person stands on the road, and a car is approaching him/her, then the car will gradually grow bigger according to our visual perception. When the car was far from the person, the ``point mass'' approximation was valid, but as it approaches, the approximation fails, although there is a perception of motion of the car. Therefore, the hypotheses of geometry certainly does not hold all the way. Then, what is the way of describing such motion?

I have a state space model of the system with dimension of various matrices as follow,

A = 4*4

B = 4*2

C = 2*4

if initial condition for a basic system not be zero(cause, system not response) then how much can be put initial condition for the system observer?

or how can find the initial condition for observer that the best response for observer?

The linked file is a proof that the axial Doppler shift changes observed time:

Being a Doppler shift it changes observed distance dimensions also. That if a point on an observed object is measured in observers world to be at x,y,z,t =6,9,2,0 in the world of the observed it is at x',y',z',t'=3,-7,9,5 assuming a relativistic velocity between the observer and the observed. Unlike the transverse Doppler shift it is proportional to the cosine of an observation angle.

Hello

To start off, the question deals with non relativistic system.

It is known that Biot-Savart law gives the magnetic field at position

**r**(the position of the observer) , created by a current density at position**r"**, if the current is static and the element is stationary in the observer rest frame. In the case of a time dependent current, one may use Jeffiminko equations to account for the delay.However if the current element is moving with respect to the observer in a non inertial reference frame. Can we still use Jeffiminko equations ?

Thank you in advance

I would like to compare the intra and inter observe reliability in three different groups (each has 3 observer). How can I do this? Cohen kappa and Fleiss' kappa are for individuals and Fleiss' kappa can help for individual intraobserver analysis. Findings are categorical. But what should I have to do for interobserver analysis of groups, should I get the mean or do you suggest something else?

Dear colleagues,

the majority of EKF/UKF implementations for speed sensorless control of PMSM are in alpha,beta frame (i.e. observer is implemented in stationary frame). I wonder why? Equations in dq fame are much more simpler, so the computational requirements should be lower. Is there any evidence that observer doesn't work implemented in dq frame?

And what will be the speed of the wave perceived by an observer sitting at the source itself, which is moving ?

The speed of a ball thrown from a moving source ( Inertial ), is seen differently by the person sitting at the source and a person standing somewhere else (a inertial frame though). Why can't the same approach be applied to wave ?