Connection Definition and 498 Threads

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Hi All. I hope this question makes sense. In the case of Fourier Transforms one has the complex exponentials exp(2..π i. ξ.x) In 3-D, if we single out where the complex exponentials are equal to 1 (zero phase), which is when ξ.x is an integer, a given ( ξ1,ξ2,ξ3).defines a family ξ.x= integer...

Does a symmetric connection implies that torsion vanishes?

For as long as I can remember, the typical speaker connection on computer motherboards has 4 pins and the typical speaker has a 4 slot female connector with only two wires leading to the speaker. Is a there a technical or historical reason for the 4 pin connector?

So I am stumped by why these capacitors are there, to my understanding the capacitor C3 acts as a low pass filter but then I don't quite understand the purpose of C1 and C2 as indicated on the picture.

Many people talking about there are similarities and common positions in quantum entaglement and superposition with entropy. I need to know about this phenomenon

I designed two geometries (one for beam/line reinforcements and other second for a solid block shown below) in Ansys workbench spaceclaim for static structural analysis. In Ansys workbench Mechanical, I got a weird mesh for the reinforcements which I modeled as beam in Spaceclaim (shown...

My background is that I'm an applied mathematician and engineer, self-taught in GR and QFT. It's an old idea, in some dozen or so SciFi books. But I'm looking for a mathematical framework for handling it. The second law of thermodynamics, that entropy always increases in a closed system, can be...

Based on what will you choose a connection to be affine or non-affine? It seems to me that it's always more easy to work with affine connections, and I've seen only them being used in General Relativity. Are non-affine connections forbidden in the theory?

Dear PF, I need to have a simple mini-camera with wire connection... (i don't want wireless transmission). if i get for example an ordinary small FPV camera...

Hello, I'm trying to find the best way to waterproof a wire connection. As you can see in the image I've got three wires connected together with a bit of electrical tape in place. I can't fit a standard junction box because the wires are soldered together. Is there anything I could use that...

What is the connection of relative permittivity and bandwidth of an antenna? Higher relative permittivity resulted in high wider bandwidth?

Homework Statement Question: For the circuits shown in Fig. 6, voltage meters and ampere meters are used to measure the voltage across the load and their current flow. If the Red Probe is plugged into the “+” terminal of the voltage meter and ampere meter, which circuit(s) show both the...

I ran across exercise 2.8.4 in Oneill's Elementary Differential Geometry. It says "Given a frame field ##E_1## and ##E_2## on ##R^2## there is an angle function ##\psi## such that ##E_1=\cos(\psi)U_1+\sin(\psi)U_2##, ##E_2=-\sin(\psi)U_1+\cos(\psi)U2## (where ##U_1##, ##U_2##, ##U_3## are the...

Some models of gravity, inspired by the main theme of spacetime fabric of Classical GR, treat the metric of the manifold and the connection as independent entities. I want to study this theory further but I am unable to find any paper on this, on ariXiv atleast. I will be very thankful if...

Nerds are usually considered bad in sports. But in some sports, they seem to be in fact better than average population. For instance, it seems to me that they like mountaineering and climbing more than average population. What are your experiences?

Hello. The curve y = x2 is a parabola that looks like this: I have a shape Square that looks like this: What I am noticing is that if I consider the equation y = x2 and also the shape Square, I find that there is no connection between them but the equation y = x2 is pronounced as x-square...

Homework Statement Explain the following order of the boiling point (° C) HF (19.5)> HCl (-85.1) <HBr (-66.8) <HI (-35.4) b) Explain the following order of connection distance (pm): HF (92) <HCl (127) <HBr (141) <HI (161) Homework Equations xxx The Attempt at a Solution a) HF does hydrogen...

Hello PF, in Carroll’s “Spacetime and Geometry”, he works out the transformation law for connection coefficients in his introduction to covariant derivatives, and I’m wondering if there is a typo in the final equation. He starts with$$\nabla_{\mu} V^{\nu} = \partial_{\mu} V^{\nu} +...

[Moderator's note: Spun off from a previous thread about Maxwell's Equations and QFT.] Perhaps, but Christoffel connection is also an observable. You feel it in your whole body when you accelerate. One usually calls it the inertial force.

I was thinking about connection coefficients. Can we choose a coordinate system so that we have a Levi-Civita connection? Or is it a thing imposed on us by the manifold? EDIT: I realize that, from a geometric perspective, since we'd be dealing with a manifold we would have no torsion around any...

Let the metric be defined as ##ds^2=dr^2+r^2d\theta^2+r^2\sin^2\theta d\phi^2## Through some calculations, we then see that our connection one forms are ##\omega_{12} = -d \theta## and ##\omega_{21}= d\theta##, ##\omega_{13} = -sin\theta d \phi## and ##\omega_{31} = sin\theta d\phi##...

Hi all! Wanted to know if this is along the right lines, or if I'm missing anything... Any help is greatly appreciated :) 1. Homework Statement Explain the connection between a graph of potential difference versus current, and Ohm’s law. Homework Equations slope = rise/run V=IR R=V/I The...

we know the fact that nerve cell can receives, processes, and transmits information through electrical and chemical signals and actually i am an 2nd years electric and automatic engineer so when it come to the field of biology i am not so good so if you try to make a special thread that can...

Hello, Is the Berry connection compatible with the metric(covariant derivative of metric vanishes) in the same way that the Levi-Civita connection is compatible with the metric(as in Riemannanian Geometry and General Relativity)? Also, does it have torsion? It must either have torsion or not be...

Hello! I have learned Riemannian Geometry, so the only connection I have ever worked with is the Levi-Civita connection(covariant derivative of metric tensor vanishes and the Chrystoffel symbols are symmetric). When performing a parallel transport with the L-C connection, angles and lengths are...

Hi, why a wired-logic gate does not produce a physical second-level gate ? Is it due to the velocity of the components that create the "wired-connection" ? Thanks

Homework Statement Two 3-phase 60-hertz 35-kilovolt synchronous generators (G1 and G2) each have synchronous reactances of j9 ohms per phase with negligible armature resistance. They are connected in parallel to supply a 36-megawatt load at rated voltage and power factor of 0.90 lagging...

Homework Statement Let V be a Levi-Civita connection. a) Let ##f \in F(M)##, (function defined on the manifold M). Show that: ##\nabla_\mu \nabla_\nu f = \nabla_\nu \nabla_\mu f ## b) Let ##\omega \in \Omega^1(M)## (one form on M). Show that ##d \omega = (\nabla_\mu \omega)_\nu dx^\mu \wedge...

Hello! Since connections in general do not require that we have a Riemannian manifold, but only a smooth manifold, I find it kind of weird that the only examples of connections that I find in the internet are those which use the Levi-Civita connection. So, I wanted to know of any examples of...

Homework Statement Transfer data from stand-alone application written in C/++/# to web application written in C#.NET. Transfer data from web application written in C#.NET to stand-alone application written in C/++/#. Homework Equations The stand-alone application runs on my PC and the web...

I have 50/50 mbps. I can get 150/150 for $22.00 extra per month. Plus I get some custom TV channels. Anyone think it's worth hit? Even putting aside the TV stuff, is that connection that much better? We have 4 devices (2 ipads, my laptop, and a satellite TV thing) using the internet...

Hi, I need to connect my TCK type K to the brass component which has working temperature approximately 200degC. I intend to drill/tap a hole in the brass (M3) and fix TCK to it with a bolt. I wonder whether using ring crimp terminal as the tip for the termocouple would be a good option...

im attatching a bolt to the inside of a pvc endcap i plan on having a metal plate on the outside so the connection is distributed over an area larger than the nut my question is, reguarding strenght of connection, and integrity of endcap is it better to go with a single hole (eye bolt) or 2...

I'm trying to understand connections and their arbitrariness. Many diff. geom. books or webpages appear to be contradictory. A chapter or page on connections may start off stressing that a connection is an arbitrary method of mapping between tangent spaces, then shortly after, show that nice...

I just spent some time on Wikipedia, learning about Schumann resonance, and had a question: How does the Schumann resonance relate to thunderstorms? Is there a direct relationship between the Schumann resonance and the lightning activity; the number of lightning events per second for example...

Hi! According to the book "Renewable Energy on Power Systems" by Freris & Infield, the voltage rise due to injection of power in pcc can be estimated from the Thevenin equivalent representing the network "upstream" pcc (Figure 1). The Thevenin voltage can be taken as the nominal voltage in the...

I'm currently in a GR class and have come across the notion of parallel transport, and I've searched and searched the last few days to try and understand it but I just can't seem to wrap my head around it, so I'm hoping someone here can clarify for me. The way I picture parallel transport is...

Homework Statement For a Particular system the following expression for Gibbs free energy is known: G = -kTN ln (a T^(5/2) / P) where a is a constant (whose dimensions make the argument of the logarithm dimensionless). Obtain expressions for a) The entropy, S b) The connection between V, P...

Could someone provide a good explanation as to why light's frequency doesn't change under refraction? The textbook I'm using gave us a two step derivation and I don't really feel like it did a proper job in explaining anything (it's Haliday). Also, a slightly *crackpot* follow up question -...

I am trying to understand Wen and Zee's article on topological quantum numbers of Hall fluid on curved space: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.69.953 They passingly mentiond the fact that a spinning particle with orbital angular momentum $s$ moving on a manifold with...

Here's a new one, but in the past couple of weeks I have to reboot my windows to get the internet connection started up again. It happens with all my browsers installed, Edge (which I do not normally use), Firefox (my default) and Chrome (backup). Someplace a setting is hanging up or a driver...

I need details on this topic ,this is my assignment but my solid state physics is not so good,and don't know much about it but i have to do this assignment ,i have material on reciprocal lattice but for only including in assignment ,not for my understanding,so i directly need any material on...

Good afternoon, I am currently trying to unnderstand Community Solar projects. I know how it works in the US and Europe but in our country the regulation of Net Metering does not exist. Can I find someone in the community who has thought about connecting retail clients or industrial clients...

Homework Statement Hello everyone. The problem is related to these two capacitor connections: In the enunciate it is said that these two are equivalent and it is requested to prove that: C1=(CxCy+CyCz+CzCx)/Cx C2=(CxCy+CyCz+CzCx)/Cy C1=(CxCy+CyCz+CzCx)/Cz Homework Equations C=Q/Vab...

Hello! I try to think about the Foucault pendulum with the concept of parallel transport(if we think of Earth as being a perfect sphere) but I can't quite figure out what the vector that gets parallel transported represents(for example, is it the normal to the plane of oscillation vector?). In...

Homework Statement For a balanced star connection i have given angles for V1=90 V2=0 V3=-90 i have to find the voltage required to produce the same phase currents as in standard three phase voltage source e.g V1=120 V2=0 V3 =-120 Homework EquationsThe Attempt at a Solution Im not even sure...

In ANSI/ ESD S20.20 standard, do you know what "Personnel Ground wrist strap Connection (non- monitored)" test for? Regards, priss

The Berry connection ##\mathcal{A}_{k}(\lambda)## of a quantum system is given by $$\mathcal{A}_{k}(\lambda) \equiv -i \langle n|\frac{\partial}{\partial \lambda^{k}}|n\rangle,$$ where the ket ##|n(\lambda)\rangle## depends on the parameters ##\lambda^{k}, k=1,2,\dots## in the system. The...

In the presence of torsion, is it correct to say that the metric doesn't give rise to a unique connection? So, if we were using, say ECKS theory, which unlike GR includes torsion, in order to find the connection, we'd need not only the metric, but a specification of the torsion. My thinking is...