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How can I create uniform laminar flow in a short duct?

I have a small vessel with a rectangular cross-section which needs to be ventilated at a relatively slow rate, ~$3\ \tfrac{\text{L}}{\text{hr}}$. The connections to the vessel will be tubes with an approximately 0.5" diameter, but the cross-section…
Chris Mueller
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Analog PID controller - settings wrt $V_{err}$ - setpoint always higher than room temp

I designed from scratch an analog PID controller to mantain a temperature selected in the range of 60 to 80ºC with a room temp say = 20ºC. The "plant" is a simple 4R7 5 W resistor heated by a PWM-controlled current (100% to 0% range). For any given…
atferrari
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Sinking speed of particle in shear thinning fluid?

For Newtonian fluids, the sinking (or rising) speed of a particle is (reasonably) well known. What is a relationship for shear thinning fluids?
mart
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Use of 410 Stainless Steel for replacement of 420 Stainless Steel

Can we use Grade 410 Stainless Steel for replacement of Grade 420 Stainless Steel? The application is for engineering components which have torsional and fatigue load. The reason for the substitution is that 420 is not commonly available in the…
Parthiban Durairaj
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Statistical approach to defect detection and prioritization

My company has over 100k communication devices deployed. We collect failure information from the devices. We have two type of data failure count per hour for each device and we use that to calculate failure percentage. We are developing a pro active…
Jonab Kornell
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What is this kind of X-Y motorized system?

I'm wondering what the technical name is for this kind of stepper-motorized arrangement (a positioning system? an XY table?)? What is it typically used for? It appears to have two steppers as opposed to generic DC motors, so it's presumably for…
OrCa
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How can I get a quick 2B shine on grade 316 stainless steel?

I have a stainless steel (316) 2B finish strip. I tried buffing the material for a shiny surface but it takes lot of time to finish my production. So, I want to know if there is any chemical available or any more simple process which I can do…
Dipak Panchal
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How does non-electrical ATEX apply to springs?

This question relates to the ATEX directive, which is the European regulation governing the design of products to be used in explosive atmospheres. In particular, I am asking about the part relating to non-electrical (i.e. mechanical) devices. Does…
Time4Tea
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Arranging members within a truss efficiently

A wide variety of trusses exist for bridges and roofs. There are many different permutations when it comes to arranging the internal truss members. Depending on the direction, a diagonal member may be subjected to either compression or tension.…
Question Overflow
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Measuring the distance to an object with RF resonance

Assume I put an RF antenna in front of an object (typically the face of someone sitting in a chair, so able to move about +/- 10cm in all directions) at a typical distance of 1m. If I consider the system antenna/face as a resonant cavity, I'd get a…
Julien
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How do cyclonic vacuum cleaners maintain collection efficiency with constant motion and changes in orientation?

Anyone used to doing housework has probably noticed that vacuum cleaners come in both "bagged" and "bagless" varieties. If you're of a certain age, you may have noticed when these "bagless" vacuums appeared back in the 1990s. Though I didn't…
Air
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What is the accuracy of direct metal laser sintering (DMLS)?

They've printed jet engines with it that work after polishing. So how is the accuracy measured and how accurate is the DMLS process? I can't find the required info anywhere.
Daniel Donnelly
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Difference between continuous wave laser and a pulsed laser

I understand the difference between the two in terms of how they function; one will release all of it's energy in small pulses with the other creates a constant stream of radiation. My question is for materials processing such as marking or cutting.…
Jonny Flowers
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How small can you get a stream of molten steel to be at low pressure?

I'm designing a crucible / extruder, and right now it has a .6mm hole to extrude from. Will this work? A chart with various metals listed would be nice. Pictures: Click to expand
Daniel Donnelly
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Efficient 3D mesh topology for CFD simulation of turbine blade

I´m developing a tool to generate an openFoam wind tunnel case of a wind turbine. I already have the blade geometry constructed, but I'm really new to CFD and parametric meshing. I found some articles where they mention a C topology to mesh the…
efirvida
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