Issues Definition and 407 Threads

Hi PF! I'm using a mac and am running the CFD program openFOAM. As I'm going through a tutorial on openFOAM, I am instructed to type paraFoam & into the terminal. When I do so, I receive this error: This application failed to start because it could not find or load the Qt platform plugin...

Hallo All! Im glad to be here... I have written a paper on a new type of network for NLP but i have lingering questions on how efficient and effective it is...this is a link to it on my blog... ABSTRACT submited So the following is a more formal framing of efficiency and effectiveness in...

Hi physics forms! I'm practicing to for an Quantum mechanics exam, and i have a problem. 1. Homework Statement I have two problems, but it's all related to the same main task. I have a state for the Hydrogen: ## \Psi = \frac{1}{\sqrt{2}}(\psi_{100} + i \psi_{211})## where ## \psi_{nlm}##...

Hello everyone, I'm sure a lot of you know that the Christoffel symbols are not tensors by themselves but, their variation is a tensor. I want to revive a post that was made in 2016 about this: The Variation of Christoffel Symbol and ask again "How is that you can calculate ∇ρδgμν if δ{gμν} is...

Disclaimer: I forget the names of tools often for some reason so I will often describe the tool rather than say it's name My shop teacher recently told me one of our machines is 45 years old. If I recall correctly it is the planar (device used to flatten the faces of wood). How long do you...

Greetings All, So I've received my first round of rejections from schools, and I must admit I am a bit surprised. This is my second degree, with my first being in EE from 12 years ago. At that time I had pretty severe (and documentable) mental health issues, and this really held me back...

whats the deal with February. is the month 28 days or 29 days? every 4 years we have 1 extra day? what the hell. every year should be almost exactly the same length.

I recently ran across a review of the new movie "Downsizing" (starring Matt Daman and Kristen Wigg (together again from "The Martian")). The main issue in the movie seems to be shrinking people will reduce their environmental load on the planet (smaller people use less stuff). However, as any...

So I picked up this book (Lehninger) for being too expensive, because obviously the more pricey the book is, the better it's quality in learning... stuff... and content... it probably cures cancer, who knows? Anyhow, so I am reading through the book and I come across a passage I don't fully...

I'm working on a public area audio system where we need to install our horn speakers on big height as per their installation requirements. We designed a metal pole as described: Pole consists of two poles: 1) a 7.5 meters height, 10" diameter, 6mm thickness. 1.5 meters are to be buried...

Hi all, I have dreamed of doing research in biophysics to develop organic nanomachines which can treat people's medical problems by rebuilding them from the bottom up. The root of this comes from my own life experience. I grew up with unidentified learning issues as well as emotional and social...

Is there a book/report(s) that can shed light on this issue? I am into making custom projects that are powered by engines and one, in particular, I am very interested in making sure I don't get any induced vibrations or oscillations. Suppose I have my engine affixed to a frame and I wish to...

Hi PF! I am trying to copy info from MATLAB to Excel via the following code filename = 'testdata.xlsx'; A = [12.7 5.02 -98 63.9 0 -.2 56]; xlswrite(filename,A) but I receive the following warning: Warning: Could not start Excel server for export. XLSWRITE will attempt to write file in CSV...

The condensate drain from a steam condenser is expected to be about 50 deg C. It's only 38 deg C or so. There's a mix of steam and non condensable gases coming into the condenser. Its pressure seems slightly higher, being about 0.25 bar abs instead of 0.2 bar. What does it indicate? Also, no...

Homework Statement Hello! Last week I have came here for the help related to this problem. I am creating a new thread to describe the issue more precisely. I will be grateful for your help and explanation. I post the explanation for the book first accompanied by attached pictures, and below I...

Well this latest version of malware is causing issues around the globe. I was shocked to learn of the infection of NHS systems in the UK, and this morning I read of German train station timetable boards affected...

Hello, I used the Darcy Friction Factor from the Moody Diagram along with the Reynolds number to find energy losses inside the cold air tubing of our vortex system. My calculations showed that I should decrease transitions, length, diameter, and velocity. I am mainly concerned with the figuring...

I have decided that I want to pursue a career in physics and chemistry. It is very important to me that my career helps people. While I know that there are current testing and research being done for cures and treatments to numerous diseases, I don' think that biology is the field for me. Thus I...

I am working on a project for a cube-sat to go up on a balloon to 40 km. My team has been talking to some other groups who have worked on other cube-sats who say that our resistive heaters need to be Kapton heaters rather than 1D heaters like what we have designed for. They claim that our...

Hi i have a question i know the answer to but don't understand how it was reached. [(8x^1/2)/(x^2/3)]^1/3 it comes to 2/x^1/18 but how? I got 8/x^1/18 thx

Let's say a company sells a toy called Tree Frog. Can the company be sued if the toy does not look exactly like a real tree frog?

If given the cross section for ZZ* to two leptons, is it possible to work out the cross section for ZZ* to just electrons or muons from it? So excluding the tau decay mode, unless ##ZZ^{*} \rightarrow \tau + \tau## can't happen anyway? I'm guessing it wouldn't just be two thirds of the ##ZZ...

This is a simpler issue but I need some help nonetheless. I have been carrying out an investigation on how the dielectric size of a capacitor affects its time constant. In theory the larger the dielectric the smaller the capacitance and therefore the smaller the time constant. However although I...

So I was attempting to modify a microwave transformer by wrapping my own secondary coil. The first coil was standard from the microwave, around 16 gauge wire, 100 turns, so I was wrapping my coil with around a 16 gauge wire, I put it together, put a weight on the transformer to keep it together...

For work I had to go get a new windows 10 laptop for various reasons. I'd also like to add Ubuntu 16 on it and dual boot. Anyone know of any reasons why this might be a problem? I remember reading a while back concerns about UEFI bios stuff locking up the computer. I'm getting tired...

Hi all , just curious if someone knows of any issues of Separation of Points in Ordinal 3-valued Logistic Regression. I think I have an idea of why there are issues with separation in binary Logistic -- the need for the S-curve to go to 0 quickly makes the Bo term go to infinity. Are there...

I have an overhead crane and we are having some issues with the gearboxes that drive the bridge. The total crane weight is 44250lbs and has a 4 ton capacity. The wheels are 13.5 inches in diameter and have a wheel load of 16500lbs. The gearbox is driven by a 2HP electric motor at 1750rpm...

Okay so i am building an incremental game and have a formula to work out how much it will cost to buy a set amount of buildings. This is required as each time you buy a building the price for that building goes up.This formula is as follows: ((BaseCost * (1.07^b - 1.07^a)) / 0.07)BaseCost =...

Hi all, I graduated from university with a BSc in Physics (3rd class) in 2000. I was having some issues with depression then in my university years but I managed to graduate with a B average in my basic degree. In 2005, I was warded in a psychiatric hospital and diagnosed with schizophrenia. I...

Guys, I'm having a lot of issues where I work with a sewage scraper bridge chattering it's drive contactors when being called to run, the coils for the contactors are switched on their neutrals from an Allen Bradley logix processor. The control circuit is 24v AC. I've spent a few hours on this...

Great thread!: https://www.physicsforums.com/threads/micromass-big-integral-challenge.867904/#post-5450007 I have a 16GB i7 windows 7 box with Firefox v45.0.2. I have NO add-ons to Firefox. Every time I open the one thread, it takes longer and longer - literally a minute the last time. No...

This is a on off switch for a McIntosh 2120 stereo power amp. It is a snap switch of sorts built in a potentiometer case with the switch attached. The shaft is 25mm. Due to the fact that it closes a relay I don't think it has much current running through it. I just can not seem to find anything...

Hello! I was just wondering what this community is aware of in the world of modern nuclear physics. To be specific, for my assignment I am asked to research a topic or issue that is related to nuclear physics (and has relations to our daily lives). Some examples provided are: The use of...

Homework Statement Having issues with the some signs when applying kirchhoffs law. When you take the derivative of charge with respect to time, is it always -i? I figured if it's charging, the change in charge with respect to time would be the same as just i, but if it's discharging then it...

I am having some trouble finding out the Maximum shear stress, I worked out my hoop stress and axial stress for the thin cylinder theory but the radial stress i am having issues with. If the applied pressure is only internal then would the radial stress be 0.

A user types a word and a number on a single line. Read them into the provided variables. Then print: word_number. End with newline. Example output if user entered: Amy 5 Amy_5 #include <iostream> #include <string> using namespace std; int main() { string userWord; int userNum = 0...

Hi I created a program to run a random walk in 1d with only input the number of steps and the number of walks. I used a random number generator to produce only two outcomes (step forward and step back) and in the main function I want to calculate the average of x (over a number of walks) and...

I graduated in 2014 with a B.A. where I studied both Physics and Spanish, and I was a few classes away from a Mathematics minor. In college I also played baseball and worked as a RA for all four years, which led to me not doing internships but I worked odds and ends jobs such as tutoring, golf...

Hi, I'm new to these forums so please forgive me if I am posting in the wrong section. Do you think it's possible for someone with chronic health problems to work as an engineer? More specifically, someone who is a recent cancer survivor who deals with chronic fatigue, gets sick easily, etc...

Is D wave 1024 qubit quantum processor can solve a 1024 cities 'travelling salesman problem' ? And if not what are the abilities of it ? Thanks in advance

hahaha, not really something you want to hear from the air crew

We know that clocks slow down if moving relative to something that's still and clocks speed up if still relative to something in motion. So, what if I was moving relAtive to something that's still and still, at the same time, relative to something that's in motion? How can time go quicker and...

Homework Statement The average number of mRNAs in the cell at any time t is <m>(t) = Σ m * p(t). Sum over all the differential equations derived in a) in order to obtain a differential equation for <m>(t) Homework Equations So the differential equation I got in a) was dp/dt = (-kp * Pm) - (m *...

One question is, I need a rod that both has grooved bearing tightly fit and a linear bearing on the same rod with no slop. Is this possible? What is a "press fit" tolerance? If I have a 0.5 hole, what size rod will be press fit? What size will locate without pressing? Boy I wish I had an...

I have a new Dell laptop: https://www.amazon.com/gp/product/B015SHDRRW/?tag=pfamazon01-20 It came with Windows 8.1 and I put Windows 10 on. Problem I'm having is with the Bluetooth. The Bluetooth doesn't seem to be able to locate things such as my headphones or wireless speaker. I've looked...

1. Homework Statement Find a formula for the nth partial sum of the series and use it to find the series' sum if the series converges Homework Equations 3/(1*2*3) + 3,/(2*3*4) + 3/(3*4*5) +...+ 3/n(n+1)(n+2) The Attempt at a Solution the first try, i tried using partial fraction which equals...

Having terrible time learning probabilities - so this question threw me. Joe throws a die 4 times, what is probability of him getting a number 1 at most once? Hope you can help - learning binomial formulas, poisson & hypergeometric. Hope someone can assist.

That's the name of my band, and we're having some problems. Well, problem. Let me just start off by saying I don't necessarily expect this site to give me a solution, but I would really like some advice. Background: We've been a band for 5 or 6 years now (3 of us, 1 is new ~1year in), we...

Homework Statement Hello! Binary search requires O( log2(n) ) operations in the worst case. My math doesn't add up. I would be grateful for help. Homework Equations For example: Find number 8 in the set 1234578. The Attempt at a Solution The set contains n = 7 elements. 1) take the middle...

Who are the top contenders for 2016 POTUS and what are the major issues (and each contenders' stance on them)? Discuss, discuss, discuss... All I know is that Hillary and Trump look like the most popular at the moment.