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1,982 questions with no upvoted or accepted answers
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18
votes
1answer
338 views

Is there a method to determine the runoff for arid areas in developing countries?

Note: this question was totally rephrased and expanded on, addressing the comments and questions posed to the first version. The de-facto standard source for runoff calculations in South Africa is ...
11
votes
1answer
142 views

How do the bubble oscillations in two-phase flows affect the dissipation rate of turbulent kinetic energy?

I am investigating the effects of bubble oscillations (calculated using the Rayleigh-Plesset equation for bubble dynamics) on the turbulence in two-phase flows. Since I am using cryogenic fluids, the ...
11
votes
0answers
283 views

Determining RTK parameters for runoff analysis

I am examining a watershed and determining runoff using the RTK method. I basically use a 'guess and check the hydrograph' method right now. I've seen calibrators that use a mutation and convergence ...
8
votes
1answer
109 views

Can high alloy tool steels be quenched in brine?

It is will known that most of tool steels are quenched in oil to prevent cracking and distortion which appears when quenching in water due to non-uniform cooling caused by formation of insulating ...
8
votes
0answers
167 views

Forcing a part into “home position”

I have a design with two parts (at the moment): a fixed 10cm ring with vertical tracks a freely rotating block with a cut that may freely slide along that tracks: I'm trying to find a low profile ...
8
votes
0answers
131 views

Sketching an engineering system in healthcare

I am about to do a project about engineering systems in a Systems Engineering course. I need to sketch an engineering system in which clinical decision support systems are being used to diagnose ...
8
votes
0answers
1k views

ANSYS APDL Shape memory effect option of SMA not working

I am trying to define the material properties of a shape memory alloy material in ANSYS APDL V15. There are material properties for Superelastic materials (SUPE option) and material properties for ...
7
votes
1answer
101 views

How can I estimate blocking window distance in an sCMOS sensor setup?

I am trying to establish an appropriate distance between a spectrograph output window and a CMOS sensor. The spectrograph creates a focused image on the CMOS sensor but I am trying to restrict the ...
7
votes
0answers
437 views

BER peroformance of MPSK and MQAM in Rayleigh fading channel

I have a question regarding bit error rate (BER) performance over the Rayleigh channel. I observed BER performance over the AWGN channel using Simulink in MATLAB. I used to change the "SNR" parameter ...
7
votes
0answers
5k views

Residuals of continuity not converging

I'm simulating a turbine. The convergence of solution is monitored by checking the residuals of the numerically solved governing equations. The "viscous-spalarat-almaras" model is used, and used air ...
7
votes
1answer
592 views

Tolerance for Beam With Cope End

I need to have some beams fabricated with copes on the ends. They will be set on top of existing steel trusses, and used to replace undersized purlins to shore up existing rafters (hence the need ...
6
votes
0answers
86 views

Identify this bomb disposal equipment

A recent news item featured this photo of a WW2 bomb being prepared for detonation. Can anyone identify the purpose of the large widget sitting on the bomb? it's got a lot of cooling fins on it, and ...
6
votes
1answer
272 views

Thrust distribution of engine

I am studying the thrust distribution of jet engines. But I'm now a bit confused. In Rolls-Royce's "The Jet Engine" book, http://aeromodelbasic.blogspot.com/2012/05/thrust-distribution-distribution-...
6
votes
1answer
660 views

Design of transverse reinforcement in a wide beam

Besides satisfying nominal bar provision in the code, is there any special requirement in the provision of transverse reinforcement to ensure that the longitudinal reinforcement is fully effective in ...
6
votes
1answer
134 views

How to optimise feed-forward control of a process based on a prediction using the prediction confidence?

I'm looking for a control method for a production process with the following characteristics: 1 control variable many process parameters (+-50) 1 resulting variable continuous measurement of ...
6
votes
0answers
513 views

How does LTE eNodeB set the Base Station output power?

I'm interested into the power radiated out of an eNodeB (LTE/4G) radio base station: which parameters does this power depend on, if they are constant or relying on the environment... All of this in ...
6
votes
0answers
426 views

Incompressible 2D pressure-driven flow: for Navier-Stokes equations in nondimensional form, how should I express pressure boundary conditions?

*I have updated this question. I'm using two codes for modeling incompressible, two-dimensional flow out of a tank. My fluid dynamics experience is pretty basic; I'm using the codes to understand a ...
6
votes
0answers
252 views

I-beam annotation for tube on drawing

I have been sent a clip of a drawing with the following annotations on it, but I've never seen them before and can't figure out what they mean. Is there a standard interpretation of these callouts? ...
6
votes
1answer
644 views

(Non)simultaneous prestressing anchorage slip losses

Post-tensioned prestressed concrete beams suffer from a multitude of losses. When jacked, they suffer friction losses and their tension diagram is, for example (to simplify the drawing, I'm using the ...
5
votes
1answer
71 views

LED Lumen Calculations

I am using an LED as a point source for a school project. I have two questions in regards to the LED(s). I know that light follows the inverse square law when measuring perceived brightness, but all ...
5
votes
0answers
121 views

I want to understand this pneumatic circuit

I have trouble understanding the following pneumatic circuit diagram: I am new to reading circuit diagrams and i am unfamiliar with some of the symbols. I would appreciate if somebody could explain ...
5
votes
0answers
63 views

What diameter of particles will result in a blocked borehole?

My mine is looking to install a 600 mm open borehole to drop particles up to 150 mm through. It's a 320m shaft to drop ballast down to save time compared to using the drift. When it gets blocked ...
5
votes
0answers
27 views

Why do modern MRI scanners use an axial static field?

Last night I was reading some fascinating history of the first full-body MRI scanner and noticed that it's fundamentally different from modern scanners in one particular way: the static B field is ...
5
votes
1answer
138 views

System Dynamics Modeling

I am trying to model this system but am having difficulties in setting up the equations of motion. This is a simplified model of a motorcycle suspension system, where P is the ground in the image ...
5
votes
1answer
237 views

Industry standard factor of safety for ballast design

What design standards exist for the design of ballast against uplift forces, and what factor of safety against uplift do these design standards promulgate? I am familiar with a typical FS of roughly 1....
5
votes
1answer
405 views

Building RF power meter

I want to build power meter for wifi signals. One way to do it is to use a diode to rectify AC signal and amplify that before measuring. But are there diodes which work at such high frequency? Also, ...
5
votes
1answer
140 views

Derive a heat equation for a shrinking nanoparticle

I consider a spherical nanoparticle (NP) that is shrinking, for instance due to a melting process. I know that the pressure $p$ is proportional to $1/R(t)$, where $R(t)$ is the radius of the NP at ...
5
votes
0answers
135 views

Nozzle Sac Pressure Estimation from flow rate

I have a diesel fuel injector as shown below: The common rail pressure is set at 180 MPa. We know that some of that pressure is lost through the injector. Based on the knowledge that the injection ...
5
votes
1answer
217 views

How to make a conductive paint over PDMS?

Conductive paint by conventional technique using gum and graphite powder does not stick to the PDMS surface and comes off once the paint dries. How else can I make a conductive connection over the ...
5
votes
1answer
80 views

PATRAN Order of Operations

To preface this question, almost all of my FEA experience has come from SolidWorks, so I haven't had to deal with these types of problems. I'm designing a truss structure in PATRAN composed of 1D ...
5
votes
0answers
108 views

Thin film sheet-resistance (van der Pauw method)

A well-known method to measure sheet resistance is the van der Pauw method. Looking at Wikipedia they state that the cloverleaf configuration is the most advised. Two questions naturally arise: Why ...
5
votes
0answers
110 views

What is the theory behind Eurocode 1 - Part 2: Traffic loads on bridges?

I'm interested in some theory Eurocode 1: Actions on structures - Part 2: Traffic loads on bridges. How were the limits chosen (e.g. maximum deck acceleration = 3.50 m/s2)? Why is the lower limit of $...
5
votes
0answers
96 views

How do DC motor parameters scale with motor size?

Consider the following DC motor parameters: Rotor resistance, $R\ [\Omega]$ Motor constant, $k_t\ [\mathrm{V/rpm}]$ Inertia, $I\ [\mathrm{kg\cdot m^2]}$ How do they scale with motor size? Do $R$ and ...
5
votes
0answers
55 views

Are Green strain calculations apt for volumetric strains?

I am trying to calculate large volumetric strains but I am somewhat confused whether Green strain is the right thing to be using or whether I should use good old-fashioned engineering strain. The ...
5
votes
0answers
104 views

Schematic Reading - Fluid Control Limit Switch Question

Does limit switch LS1 remain pressed on until the piston moves to LS2?
5
votes
1answer
723 views

How can we derived the equivalent Lumped Mass Model for irregular building and how to calculate the errors?

Intuitively, building can be represented as a lumped mass model ( the taller the merrier!): Assuming a building is a lumped mass cantilever column also makes the global stability checks easier ...
4
votes
0answers
73 views

Boeing 737NG pickle fork cracking. What determines the fastener layout?

Boeing 737NG aircraft are currently being checked for cracking in the "pickle fork" assembly that attaches the fuselage to the wings. The affected joint has 4 fasteners that attach the fork to the ...
4
votes
0answers
25 views

Equation for the spring constant of an orthotropic, rectangular wire spring

I hope I can get some help with this problem as I've been struggling with it for a long time. I have a helical tension spring with radius $R$ and a square wire cross section and made of orthotropic ...
4
votes
1answer
53 views

What approaches are there for demolishing a structure and how is an approach chosen?

From my office on the 21st floor of a building in Vancouver, BC two parking garages in the process of being demolished are visible. A third is just out of view a few more blocks away. One of these ...
4
votes
0answers
60 views

Flow through flattened tube

Is there an analytical solution for the Navier Stokes equation for flow through a flattened tube ( flat plate in the center and semicircular lobes at the end).
4
votes
1answer
148 views

Questions regarding Cornering Stiffness for RC Car

I am a bachelor's level student tasked with modeling the vehicle dynamics of an RC Car that will be made to drive autonomously. I lack prior experience or particularly specific education with vehicle ...
4
votes
2answers
114 views

Need some advice, control system animation. Appreciate some help!

I would like to have a 3d simulation of a helicopter landing on a ship. I thought about using matlab for this, as a far as I know you can connect models from Simulink to virtual worlds using blocks, ...
4
votes
1answer
281 views

Buoyancy force problem

I'm trying to design a kind of water valve with inexpensive materials as a first prototype. The water flow from the PVC pipe (1) reach the body of the valve and pass through an aluminum grid (3) to ...
4
votes
1answer
208 views

Deriving the amplitude of a coulomb (dry friction) damped spring

This is my first time posting anything, but I could not figure out the derivation of the amplitude of the spring for the 4 first oscillations. I am not acquainted with the effect and calculations of ...
4
votes
0answers
46 views

Could a Fuel Breathing Engine Rather Than an Oxidizer Breathing Engine Work?

Here on Earth, the atmosphere is ideal for jet engines which combust a fuel using the native oxygen as an oxidizer. On another planet, might it make sense to carry oxidizer in the fuel tanks and scoop ...
4
votes
2answers
703 views

Effective radius of a tire and rolling resistance based on information on velocity and tire pressure

I need to make an nonlinear observer of a system and need to know how the charactaristics of a tire are to get the final conclusion. I really need some good articles about how the effective radius of ...
4
votes
1answer
89 views

dSPACE compiler linker error — fscanf undefined

I'm dealing with a somewhat intractable problem. We're running dSPACE 7.4 (RTI 1006) on MATLAB 2011a, which I understand uses the dSPACE DS1006 C Compiler v. 2.2. When I try to compile one of our ...
4
votes
1answer
89 views

How to compare dynamic systems of different degree of abstraction?

I'm modelling a vehicle as a multibody system in Matlab/Simulink. My goals are: Have a realistic simulation model so I don't have to do prototype measurements all the time. Solve specific parameter ...
4
votes
2answers
186 views

Arduino CNC - which vacuum pump?

I have an arduino powered CNC machine with the Protoneer v3.00 shield. I have a probe setup for auto levelling which works correctly, I get a depth map for the board. But the issue is that this ...
4
votes
2answers
305 views

How much does the elasticity (Young's Modulus) of concrete and asphalt change with ambient temperature?

I'm assuming here that all materials will have a change in elasticity due to thermal expansion/contraction and a resultant reduction/increase in the strength of the bonds of the atoms leading to a ...

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