# All Questions

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26 views

### IAM unable to solve these block diagrams

I need transfer functions for the block diagrams... IAM unable to solve those.. can I get help
37 views

### What's so special about Tesla's all-electric automobiles, compared to other car manufacturers'?

Why haven't car manufacturers caught up with Tesla's automobiles? E.g. why haven't the Chevy Bolt, Nissan Leaf, VW e-Golf driven (pun intended) TSLA out of business? I list TSLA's advantages that don'...
32 views

### Safe distance outdoors to prevent covid-19 infection?

This is an aerodynamic engineering question about the reduction in particle density over distance from aerodynamic turbulence. If we assume that a person is constantly emitting a cubic yard of ...
35 views

### Lyapunon candidate function to derive parameters estimation law

I have a system and a reference model represented in state space in the following form: \begin{gather} \dot{x} = Ax+Bu \\\ u = \hat{K}(t)x+\hat{k}_r(t)r \\\ \\ A_m = A+BK \\\ Bk_r = B_m \\\ K,k_r : \...
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### ANSYS CFD simulation for Wind Flow around Building can't get converge

I have created Hexa meshing by using ICEM CFD of a building in external flow. The procedure that, I have followed to solve my problem in post-processor but I didn't get the solution in terms of ...
40 views

### Has anyone ever flown to space in a vehicle they helped build? [migrated]

I'm sure people who build airplanes have had a chance to fly in the planes they build, and I'm confident that people who build submarines may get a chance to travel in them too. But I am under the ...
79 views

### Is there a submarine that uses fewer than 4 rudders?

This question is restricted to post-WWII submarines designed to have a greater speed while submerged and to cruise underwater (unlike WWII U-boats). As highlighted in this question, there is no need ...
23 views

### Inputting Complex Conjugate Transfer Function into Matlab

For the following transfer function, I am supposed to find the modes and zeroes. With it factored like this it is easy to do. However, with it factored this way, I don't know how I can input this ...
50 views

### Why don't all gas pipe flows end up at sonic speed?

According to the 1D models of compressible fluid flow, the effects of pipe wall friction and the effects of heat addition from the environment both drive a flow toward Mach 1 (i.e. the speed of sound)....
21 views

### Divide Flow and Maintain Pressure

Im in the process of building an espresso machine from readily available parts. I have a solenoid pump that supplies pressurized hot water to the coffee grounds. I want to be able to tune the pressure ...
18 views

### Do stators in axial flow compressors have airfoil geometry?

In axial flow compressors the role of a stator is to gradually change the direction of flow to exchange some of the kinetic energy of the flow into pressure. Therefore it stands to reason that they do ...
39 views

### Calculate forces/ torques on a parallel spring array

I am stuck on the calculation of forces on a certain system involving parallel springs. The schematic of the system is as follows: The lower plane is fixed and the upper plane movable. There is a ...
43 views

### Laser Power vs Efficiency

Is there some kind of graph or relation between laser power and efficiency. What I'm trying to find out is whether the efficiency of a laser decreases with increase in power or is it that there is no ...
40 views

### How can I solve this beam?

I want to find the elastic curve for this beam using Ansys and dividing it into 6 elements according to the finite element method. but I dont Know how apply this load.I've already been searching but ...
19 views

### multiple intersection curve driven patterns in solidworks

I created a solid of revolution using two splines. so the first derivative is discontinuous where they connect. there is no tangency relation. though I think the problem would be the same even if ...
31 views

### Best way to create separate heating zone for basement

I have 2 heating zone in the house: one for the upper floor and one for main and basement. Both zones split from the main duct into their own ducts and use a damper to close/open. Now I want to ...
40 views

### H2 Sensor in N2 environment

We develop a test station where we might have H2 leakage. To prevent explosion we are considering intertisation using N2 gas (primary explosion protection). However we also want to detect leakage ...
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### Design table driven equation driven parametric curves for sketches in Solidworks

Do these exist? I suspect they don't.. Equation driven parametric curves for sketches yes, but not with their parameters set by design table.. The closest I'll be able to get, I think, is what I'm ...
60 views

### Why aren't American cars as popular worldwide as e.g. Japanese cars? [closed]

I heard that the Japanese reverse-engineered American ones and produced them cheaper but I don't know the engineering/business reasons behind the phenomenon.
30 views

### Why 450nm laser diode is much cheaper than 488nm at same power

I am interested why 450nm laser diode costs \$75 but 488nm diode with very similar power (80mW vs 60mW) costs \$2500. Why is that? The vendors says it is due to production costs and because 450nm ...
23 views

### Accurate method or instrument to measure density of shaving cream foam or whipped cream foam?

I am currently filling a "standard" stainless steel cup of known volume with foam and then I weigh it. Then I calculate density. This method is pretty messy and I have to be careful about how I fill ...
106 views

### I can't even see how can i solve this truss question

I can't even see how can I solve this truss question I'm an engineering student, our professor assigned us this truss problem. I have found an answer saying that it is a zero member. I have tried ...
53 views

### Archimedes Principle

A crane is used to lower a vertical cylindrical pillar into a reservoir. The pillar has a mass of 4 tonnes and is submerged to a depth of 2.5m. It has a diameter of 1.1m. The specific gravity of ...
383 views

### In a reinforced concrete detail drawing what does 'reinforcement to be GK 60' mean?

Consider the following extract from a British reinforced concrete drawing from 1970: It states that 'REINFORCEMENT TO BE G.K 60. UNLESS STATED OTHERWISE' What is the meaning of GK 60? What property ...
23 views

### Basic intuition for motor torque

when shopping on digi-key or other electronics distributor, I can see the Torque - Holding spec, given in oz-in and mNm. I understand Nm in a torque context when the force is applied as a lever at a ...
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### Bending behavior of built-up C-Channel

I am analyzing a built-up C-channel for bending purposes (2 point loads of 1200 N each @ 30 cm symmetrically from the CL). The flanges are made of a different material than the web, they are also of a ...
46 views

### Need help identifying this vacuum chamber flange

I know this might not be the most ideal place to ask this question, but I couldn't think of any place better. I recently purchased a high vacuum chamber setup and have been disassembling it for ...
9 views

### Spectral efficiency of CDMA

Why is CDMA having lowest channel efficiency as compared to TDMA and FDMA? I am having a hard time understanding this. Can anyone explain?
19 views

### Effects of Solar Shield on Electronics Enclosure

I am designing a prototype of an electronics package that will sit out on a pole in the sun 24/7 with a max ambient temperature of 50˚C and at 30˚N latitude. It produces 50W of internal heat ...
95 views

### How can I calculate the total signal level (noise) of PC fans?

I have a fan on a PC case running at 100% speed making 40dB/A of noise (sound pressure). Then I add a second fan right next to it running at 100% speed making 30dB/A of noise. What is the combined ...
36 views

### How are common free body diagrams and similar illustrations made?

Over my education I've come across tons of engineering illustrations, most commonly free body diagrams and similar. I still do not know what software(s) is used to generate these. So many look very ...
26 views

### Maximum bending stress and neutral axis

I need to calculate the maximum bending stress So let $r$ equal the radius $$\frac{1}{r} = \frac{M}{EI}$$ $$\sigma_{max} = \frac{Mc}{I}$$ $$\Rightarrow \sigma_{max} = E\frac{c}{p}$$ But how do I ...
8 views

### CSI SAFE uplift results on a Raft Foundation

I have a number of questions surrounding my uplift results on a raft for a foundation I'm analysing in CSI SAFE software. I am getting uplift $+ve$ (positive) bearing pressures to the corners of my ...
14 views

### LS Dyna help required for a beginner

I am a learner. I have a keyword file for a metal cube striking on a metal plate. I need to change the cube size, orientation and velocity. How to go about doing it? P.S. went through YouTube and ...
10 views

### Are there any specifications that address the environmental conditions items traveling though international post should be able to tolerate?

In terms of temperature extremes, air pressure, humidity, shock, ... In determining what ranges to design for in a device are there any standards or at least guidelines either by postal services or ...
17 views

### How can a curve in Gabrielli-Von Karman graphs curve down?

Gabrielli-Von Karman graph plots the specific power, that is, power required to move certain weight, against speed. It gives an idea how much power is required to move certain mass at a certain speed ...
9 views

### Abaqus XFEM crack propagation

I'm trying to run a simulation about crack progation using XFEM. In particular, I have a 2D case where I'm representing a composite material composed of matrix plus a single fiber. I would like to ...
17 views

### Factoring in Efficiency in Equations

A pretty simple question, but one that's weirdly confusing me: I'm working with an equation for total water demand (Q) were w is the allowance for water wasted. w is typically 30%. Most books ...
42 views

### Archimedes Principle Question

A Spherical buoy has a diameter of 2m and weighs 3kN. It is designed to be used in a variety or circumstances by it being floated in water and anchored to the floor with a chain. Draw the free body ...
43 views

### Does the shape of a car really matter for how much gasoline it drinks?

Let's say that we have a mid-1950s "gas guzzler". Now, we take away the exterior "shell"/chassis and replace it with a modern car's. That is, it will visually look just like a modern car from the ...
46 views

### How can I calculate the airflow needed for a fan to cool a system?

The airflow needed for a system to sustain itself at 80°C with 25°C ambient temperature can be calculated with this formula: ...
28 views

I read somewhere that if for instance for a building earthquake forces are expected to be much higher than wind loads, we can increase the R (response modification factor) value, so that we bring down ...
16 views

### Cloudcompare Cut at specific coordination by one reference cut

I have almost 4 model which most be compared with with reference for every calculation , also need to do compare calculation only for some part of model so needs to cut the stl model and if i can do ...
11 views

### Cloudcompare M3C2 vs C2M signed distance outputs (reference cloud problem!)

I have two mode which using the cloud compare for comparing those together, i used the ordinary distance compare method ( C2M signed method) with this parameter as you can see here: and for more ...
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### Why do most BMS systems for li-ions and li-pos stop discharging at 2.5V? Are there better systems or is this the standard

From what i've read online, 3.0V is the absolute maximum li-ion and li-po batteries should be discharged and around 3.2-3.4 is preferable for preserving battery life. if that is the case, then why is ...