Terminology Definition and 170 Threads

hello, expert people, i am fresh mechanical engineer. right now i am reading about forging die design. i can not understand one term. i.e. upsetting or upsetter. please explain me about it.

Hello, I have just started reading some telecommunications basic concepts. I have a question regarding the following phrase: "when considering that transmission lines are used in transmitting AC signals: R << ωL G << ωC In high frequency applications the R is so much smaller than the xL...

I did a search on google but I was coming up with some mixed answers. I wanted to apply to this REU program and it said it was for students who are attending undergraduate institution. My two questions are the following: Are community colleges considered undergraduate institutions? Is a...

In terms of a torque-speed graph, for an induction motor the torque at 0% synchronous speed is roughly 150x that of full load torque and the motor only reaches 100% full load torque at roughly 95% of it's synchronous speed (depending on the rated slip)...

Terminology - the "upper state" Hi there! I'm reading a paper at the moment that describes a formula for an absorption coefficient with regard to radiative transfer. One of the variables in it is referred to as "N2". It describes N2 as "The number density of atoms in the upper state"...

The chapter I am reading is on proving limits... The terms "δ = min(δ1,δ2)" has came up a few times but what does it mean? My guess is that the distances δ1 and δ2 are some where in the interval of the distance δ about some x value.

Does anyone know why 19th Century scientists used the word "tension", meaning - etymologically- stretched, for the partial pressure of a gas? Likewise, the use of "tension" for potential [there is that root again] difference in electrical circuits?

Hi I have some comments/questions about the terminology used for dielectrics in physics textbooks. Linear dielectric means that components of \vec{P} are linear combination of the components of \vec{E}. Homogeneous dielectric means that dielectric constant is not the function of...

What do people in the industry usually mean by steel cord? Is it the same as steel wire, steel rope? Pictures, Wiki, professional article/dictionary would be appreciated. I googled it but the results are still quite too blurry. Thanks in advance!

Hi everyone. I'm trying to find a proper wording for "Calculations made to show the fatigue resistance of a railcar to which multicycle loading is applied". Would someone please advise how to rephrase the phrase so it sounds good and professional? "Railcar multicycle loading fatigue...

Often a terminology is used in Electrodynamics "in the absence of static and moving charges" of a magnetic medium. what does this corresponds to and how do Maxwell turns out to be in this situation? Please explain the context in detail.

I think we badly need some new terminology for substances that have biological effects. We need more general words for these substances, the word "drug" just isn't enough. For instance we should have a word for a drug used to alleviate the symptoms of an ailment to reduce the ambiguity...

Here are some different descriptions of Doppler shifts: 1. The gamma rays in the Pound-Rebka experiment were Doppler shifted. 2a. We make a cosmological model using coordinates in which an object moving with the Hubble flow has a zero coordinate velocity, so all galaxies are "at rest." An...

.. In his text-book "Quantum Theory: Concepts and Methods", Asher Peres (1995) writes: A: "Bell's theorem is not a property of quantum theory." - (p.162, Peres' emphasis). B: "This conclusion can be succinctly stated: unperformed experiments have no results." - (p.168, Peres' emphasis)...

Good day, and thanks for having me on you forum. I’ve been searching the web for the terminology used to explain the principal involved that causes the Dynabee/powerball wrist exerciser, rotor center pin to rotate in an opposite direction, relative to each end of the center pin. I understand...

I have two simple questions: 1) What is the scientific term for "a body that cannot affect another body"? Effectively, as if this body has a mass of zero. The body can move freely until it contacts another body, in which case it will not be able to affect the other body in any way, and thus be...

When playing foosball, what term should be used when a goalie shoots the ball and it is immediately blocked back into the goalie's own goal? My friend continues to use the term reflection to describe this action. Is this the correct usage of the term?

When working over a field of characteristic not 2, or otherwise with modules over a ring where 2 is invertible, there is no ambiguity in what one means by symmetric or anti-symmetric rank 2 tensors. All of definitions of the anti-symmetric tensors The module of anti-symmetric tensors is the...

(1) Given a sequence \left \langle a_n \right \rangle:\mathbb{N} \rightarrow \mathbb{R} = (a_1,a_2,a_3,...) \; \bigg| \; \left \langle a_n \right \rangle(p) = a_p and another sequence that's the series, \left \langle s_n \right \rangle:\mathbb{N} \rightarrow \mathbb{R} =...

Hi- Let me first start by saying that I do not have a mathematics background and I have a feeling my question is a moronic one but my attempts with "google" did not help so here I am. I am about to do an assignment (but this is not a homework question IMHO) that asks me to determine if...

What is meant by angle between reflected ray and incident ray , the angle of deviation or the sum of angles of incidence and reflection ? ( For a plane mirror )

In the sense of 'universal algebra': The natural numbers N can be presented as an free algebra with one constant (0) and one -unary- operation s(x) (i.e. x --> x+1). We have (of course) elements 0, s(0), s(s(0)), etc... Is there a good name for a set A with one constant (*) and one...

Terminology: "weep" (of a wound) Consider a typical open sore or wound -- in this case, from poison ivy contact. What do you call the yellowish secretions? I've heard it as 'weeping', but my Google searches haven't shown this to be particularly common -- and of course it's confused with...

Most of my friends, both on PF and in person, are accustomed to me using the phrase "balls-to-the-wall" to indicate a flat-out effort. It never occurred to me, until someone (in person) mentioned it earlier today, that it might be deemed offensive by some. I want to explain that there is no...

Greetings, I have a peculiar terminological issue. In a research paper I am writing, I need to distinguish between rolling wheels and rolling balls. The relevant difference for my purposes is that a wheel rotates around a single axis whereas a ball rotates around a single point. It's...

I'm just having a difficult time trying to differentiate between variables used and terms thrown around in PChem. :confused: First of all, what is the difference between "bond energy" and "bond dissociation energy" in a Morse potential curve? I thought they were interchangeable. Also, does...

It's often said that the axioms of ZFC set theory are the foundation of mathematics, but the same people who say that also use the term "class" a lot. For example, "the class of all ordinals", is apparently too large to qualify as a set. What's bugging me right now is that I read that there's no...

I'm looking for a solid material that will diffuse light throughout it. In particular I would need a thin bar with a light source at one end that will diffuse light to all sides of the bar, however, I don't specifically need a bar as long as the material can be machined. I'm trying to search...

For a Grade 9 textbook: "Many more objects exist in the solar system besides the eight major planets. These are smaller and include moons, comets, protoplanets, such as Pluto, and tiny grains of dust and ice." Is this acceptably-worded or is it misleading? My take is that the term...

Homework Statement When you have an open-closed tube, I was taught in high school that when using the equation λ = 4L/m, m = 1, 3, 5, 7, ... where m = 1 corresponds to the fundamental mode. I was taught that m = 1 is the 1st harmonic, m = 3 is the 3rd harmonic, etc. But my physics...

What does the asterisk mean?

Hi, Could someone help me out regarding chemist lingo? i) "were heated to reflux for one hour" Does it mean that the stuff was heated, or even boiling, but with condensing the vapor back to the container (so that the solvent is not lost)? ii) "the solution was then washed with 5%...

Terminology; "distinguished" I've always thought that understanding at a profound level requires real precision in the use of language. I was recently reading Julian Barbour's book, The End of Time where he regularly uses the word distinguished as an adjective, as in "distinguished frames of...

Hi I have two questions, 1. A metric space is an ordered pair (M,d) where M is a set (which some authors require to be non-empty) and d is a metric on M, that is, a function d : M x M -> R ------------From Wikipedia. http://en.wikipedia.org/wiki/Metric_space#Definition I just...

Homework Statement Hi all What is a ">" called in English, and likewise, what is ">=" called in English?

Hi. I'm trying to convey that all physical events occur at a point in spacetime describing the position and time at which they occur but it's for a presentation and there's not much room on the slides so I need to keep it brief. At the moment I have: "Any physical event can be described by a...

Homework Statement 10) Two numbers have a sum of 13. 10)a) Find the minimum of the sum of their squares. 10)b) What are the two numbers Homework Equations y=ax2+bx+c y=a(x-h)2+k According to the text: for a quadratic function in the forum of y=a(x-h)2+k, the maximum or minimum...

Hello! I'm having trouble understanding some of the terminology used to describe Misner (or Milne) Space. Some of the words that are troubling me are "Orbifold" (is this related at all to the cylindrical structure of the Misner universe?), "translation symmetry" (does this refer to the idea that...

In this PF Cosmo forum context we have to be sensitive/practical about language. How to state cosmo basics, especially to newcomers who may not have assimilated technical terms like "scalefactor" yet. This does not mean we dumb everything to the max! Introductory terms should lay a basis of...

Hi all We look at f(z)=\sqrt z . Here the point z0=0 is a branch point, but can/is z0=0 also regarded as a zero?

I was wondering if I could get some help with the terminology when it comes to graph theory. In this picture : http://en.wikipedia.org/wiki/Image:6n-graf.svg the numerical values are vertices (or nodes as some call it), so what are the edges then (are they the lines that connect the nodes)...

Homework Statement Given a field F, FS4 is a group algebra... we have a representation X that maps FS4 to 3x3 matrices over (presumably) F. Let V denote the FS4 module corresponding to X... do stuff. My question is, what the heck is V supposed to be? I assumed that V is F3, but that...

Hi everyone, When people present their data in plots, they always talk about 1-sigma errors, which I totally don't understand. Don't we use the standard deviation to tell us how far the a data point is from the "mean"? Why would I care about the mean when discussing errors? Shouldn't one care...

Hello. First, I'd like to make it clear, I am an IGCSE student who has just finished his board examinations, and is now getting ready to do is AS/A2 levels before pursuing engineering. I'm trying to do some studying on my own, outside for school, particularly in the fields of Maths and...

Homework Statement I'm trying to find out how people in the USA would refer to the following operations - i.e. what name would you give the process of doing something like this: a(a + b) = a^2 + ab (a + b)^2 = (a + b)(a + b) = a^2 + 2ab + b^2 Homework Equations N/A. The Attempt at a...

Some papers refer to Omega_0 without defining it. (Example: The first footnote on page 2 in http://arxiv.org/PS_cache/astro-ph/pdf/9908/9908159v3.pdf.) What's the normal assumption in this case? Omega_0 = Omega_m (Omega_m as in Omega_m + Omega_Lambda = 1 in LambdaCDM) fits the context, but seems...

Dear Forum, I am trying to learn more about the electroproduction of rho meson off proton. e + p -> e + p + rho One of the commonly used kinematic variable is tprime, defined as t-tmin. The definition I could find for tmin is that it is the minimal value of t kinematically necessary...

It's just the terminology but I am just unsure what it means I have 2 functions f(x) = ln(2x-1) g(x) = \frac{2}{x-3} the question is find the exact value of fg(4) now what exactly does that mean. I'm guessing we sub x = 4 into it at some point. It is asking for me to mulitply f(x) by g(x) im...

I'm doing some research on the history of particle physics from 1947-1964, and have been completely unable to find an answer to this question -- does anyone know when and by whom terms such as baryon number and hypercharge were introduced? A related question...Several of my sources cite a...

"T(1,2)=(3,4) T(T(1,2))=T(3,4)=(3,4) (1,2) and (3,4) are linearly independant and form a basis of R2, so (3,4) spans ImT. Therefore dim(imT)=1, and obviously dim(kerT)=1, so the transformation is singular." this is a solution to some problem i can't understand what is "spans an image" i...