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Questions tagged [radiation]

29 questions
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Heat Transfer coefficient calculation for hot air flow inside rectangular duct

I am working on modeling of air-heater component. A simplified representation of system is as follows: Cold air flow enters steel duct at one end. Inside duct is Calrod heating element shaped as ellipse. Follwing heat transfer occur…
user1768201
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Trapping sun heat the most - greenhouse

Greenhouse have recently caught my attention lately, which yesterday I posted in Why greenhouse's inside temperature never been infinitely hot? From what I understand recently, greenhouse gases traps the sun heat (infrared radiation) on earth, by…
gijoe
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Can air be ionized using microwaves?

I have been doing a good bit of research lately into a new form of electric "jet engine" developed by researchers in Wuhan, China; in the article summarizing the technologies used to produce this remarkable device, they state that they used a…
CJL
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What is the inuition behind the radiation view factor reciprocity?

I have known that the view factor reciprosity is that Ai x Fij = Aj x Fji But i can't intuitively explain the logic behind this, i do know that the view factor Fij is the portion of the radiation emitted by surface i that is recieved by surface j I…
Norman
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Do smoke alarms become more sensitive as they get older?

From what I understand a smoke alarm works by emitting some sort of radioactive particle and then counting how many of these particles hit a receiver. When there is smoke in between, it blocks some of the particles and so the alarm goes off. As it…
Aequitas
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Strange units with UV water disinfection systems

When retrieving information about UV systems for water disinfection I frequently encounter minimum intensity values. e.g. here: Basics of UV disinfection, page 23 All those I find are given in a unit I do not understand. Frequent value for…
Ariser
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Can cables and wires for home internet emit harmful radiation?

I am installing internet services in my home and need to run wires (Ethernet, modem, router related) along the lower part of the wall near some beds. Can people sleeping in the beds be exposed to harmful radiation (cancer-causing) from these…
Applesnax
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Where do I start with learning how to transfer data via RF

So I literally have no idea where to start but I know what I want to make. The goal is to somehow transmit 25mb/s of data across 15km with high penetration. Acceptable for reaching through trees and rocky areas in the mountains. I would like to…
Karekin_FPV
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UV radiation simulation in ANSYS

I am setting up a simulation in fluent to estimate the UV radiation dosage of an air stream passing through a cylindrical duct with the UV source in line with its main axis. It is a very simple system, one inlet and one outlet. I've done simple…
JC ME
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Melt plastic powder bed with radiant heat?

I want to melt a bed of plastic powder so that the powder bed once melted and then cooled forms a solid sheet of plastic. In order to melt the powder I'm thinking of passing a nichrome (Ni80/Cr20) wire over the bed without the wire touching the bed.…
Somanna
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How to consider the dimension of a cylinder when computing its radiative budget?

I am trying to derive a heat budget model to estimate the temprature of very small a stationary vertical cylinder (1mm) under environmental conditions. Imagine a wooden stick. Simply put, I have R = H InSW * albedo + sigma * emissivity * Tcylinder^4…
MorningGlory
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Protect equipment against electromagnetic radiation

They say that in the near future high cosmic radiation is possible. In addition, the Earth’s magnetic field is likely to weaken. I want to create something like a camera that would protect against electromagnetic radiation. What will be effective…
Vlad
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Calculate FTIR-system response functions from measurements of a calibrated black body

I need to find the response of my FTIR spectrometer. I do have a calibrated black-body source (area-emitter) which I measured at various temperatures. The system operates in inverse cm, cm-1. My approach so far was the following: 1) Measure spectra…
bebissig
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Method to simulate a dipole antenna in salt water?

I am looking to simulate the radiation pattern of a 2.7Ghz half-wavelength dipole antenna immersed in salt water. I've been using Altair FEKO software to try and accomplish this. I've tried two different ideas without much success: Idea 1) Directly…
Scott Hall
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Epoxy that can withstand up to 800C and is optically transparent?

I'm looking to use an epoxy in a high-temp environment like 800C, and one that is optically transparent at 450nm (not below 90% transmission). But i'm having trouble finding one. It can be made of any material, as long as it can be cured in a mold.
Dina
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