# All Questions

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1k views

### Determining Drill Speed

How are spindle speeds calculated for a drill bit? I've seen dozens of charts that highlight the rpm that should be used for specific drill bit types, bit diameter, and material. However, what if my ...
5k views

### How do Thumb instructions compare to ARM instructions for performance?

A colleague mentioned that Thumb instructions were significantly slower than ARM instructions (this was for an AT91SAM7S32 processor). Is this true? What are the performance benefits of one ...
13k views

### What are left justified and right justified ADC results?

The TI MSP430F20XX series has a 12-bit internal ADC output, which is right-justified. What is the difference between a left-justified output and a right-justified output? What are their pros and cons?...
1k views

### What kind of protection should I give structural steel in a natatorium (swiming pool) environment?

What would be the best type of steel to specify? Would a heavy galvanization suffice? Are there specialty paints/coatings available for this particular application? If so, how long do they last?
1k views

### Where did I go wrong conceptually when attempting to calculate the maximum force on a truss at a given joint?

In the problem statement below, the question states to find the maximum load $\vec{P}$ that the truss can support. My method of approach was: Draw a FBD for the entire structure. Generally I would ...
12k views

### What is the meaning of vorticity and circulation?

In fluid kinematics I can't understand the meaning of these terms : vorticity and circulation. Can somebody give me a description of these terms so that a lay person can understand them easily?
383 views

### Are threads machined from high tensile steel more susceptible to damage?

I have an ASTM A311-04 1.25" diameter round 1050 steel bar that exhibits a tensile strength reading of 155,227 PSI. Normally, we receive material in the 13-133,000 PSI range. The bar is machined to a ...
1k views

### How are the thermodynamics of CPUs and other chips handled?

I hear that designing the thermal efficiency of such systems is very difficult. I'm not sure why, though, and I am interested. On the one hand, I bet the heat is somehow a function of the total power ...
158 views

### Has a specific type of alternative intersection been shown to reduce congestion & accidents?

Localities in the US have different road layout and setups. For example the Michigan Left, Jersey Left/Jug Handle, vs a standard 4 way stop with left turns at the intersection. Have any of them come ...
371 views

### Does weathering steel corrode the same as carbon steel when it doesn't develop a protective patina?

Weathering steel is supposed to form a protective patina when exposed to wetting and drying cycles. This protective patina prevents more corrosion from occurring. This is what differentiates it from ...
138 views

### Saving RAM Memory when writing to 2K page size NAND flash

I am writing a driver for the Samsung K9WAG08U1D NAND flash chip. The specification of the memory chip mentions it has a page size of 2048 bytes (2kB). I am using a ...
27k views

### How to deal with a point force acting right on the hinge of a beam?

I have been attempting to solve a question where there is a point force acting on the hinge of a beam. Here is the problem: I am not sure how to deal with the 2 kN point force at $C$ ($C$ and $E$ are ...
8k views

### How do you determine the accuracy of a measurement device?

Lets say you have a measurement device of which you do not know the accuracy, and a reference measurement device. Both measure a variable $x$. The range of interest is $x_0<x < x_1$. How do you ...
575 views

### How fast should I sample with a logic analyzer?

If I have a 10 MHz digital signal, how fast do I need to sample with a logic analyzer to avoid any bit errors? Does the minimum sample rate increase if I want to attach a protocol decoder (e.g. SPI)? ...
211 views

### What's this mystery symbol on a manufactured machine?

I hope this is the right place to ask this question; if not I'd really appreciate some tips as to where else I can go for answers. The symbol above (apologies for the blurry quality) is on a Chinese/...
406 views

### Are all pressure-volume processes polytropic?

I was searching for information about pressure-volume processes when I read, in a heat engineering book, "The process is polytropic with $PV^n = \text{constant}$." How can I know that a real life ...
3k views

### How do you select the correct area to consiser for first moment of area calculations?

I have just begun studying mechanics of materials and I am struggling to understand intuitively how to select the area in first moment of area calculations. I was hoping someone has a relatively easy ...
178 views

### Best way to get rid of turbulent flows?

I am making a testing facility for pumps. This facility has to be able to handle 500 m3/h with at little turbulence as possible. The basin itself is 5 meters long, 2,5 meters wide and 2 meters tall. ...
802 views

### What liquid crystals are used most frequently in displays?

Is there a specific chemical that is used frequently in the production of liquid crystal displays? During my internet research so far, it seems as if the specific chemical composition of the liquid ...
234 views

### How do I solve an optimal control problem where the law of motion depends on some function of the state vector?

A typical optimal control problem with state vector x(t) and control vector y(t) can be expressed as: $$\max_{x(t), y(t)} \int_0^{t_1} f(t,x(t), y(t)) dt$$ subject to $x'(t)= g(t, x(t), y(t))$ and ...
584 views

### Comparing the performance of glass and granite in a heat storage application

Background I am working with a small team on a university project to build a greenhouse heat sink. This will pass warm air at the top of the greenhouse down through a chamber underground filled with ...
810 views

### Will a sacrificial anode protect any length of metal that it is connected to?

When using a sacrificial zinc anode, is there a limit to the distance that its protection will extend? The protection works based on electrical conductivity, so distance would seem to affect the ...
567 views

### How do ultrasonic proximity sensors detect motorcycles differently from cars and trucks?

My car has ultrasonic proximity sensors to help me park. I've noticed that when motorcycles whiz past me the proximity alarm goes off. I originally thought that the motorcycles were just too close, ...
180 views

### How to calculate permittivity for higher frequencies?

In many books the permittivity of a material is only listed as dielectric constant for one or a couple of frequencies. 1 kHz is used often (for example in the Plastics Technology Handbook, 4th ed, ...
397 views

### Detailing Fixed Cotton Duck Bridge Bearings

I'm looking for a justification for the use of cotton duck bearing pads without a sole plate. I'm specifically considering their use with precast I-girders. Say I have a two span bridge, simply ...
598 views

### Steam sterilization of whey in a bioreactor

I'm trying to design a bioreactor to produce citric acid with whey and Aspergillus Niger. The first step in the process would be to put whey into the reactor with some dextrose (approx. 10%). Then, ...
3k views

### Determining the difference between US Bailey Bridge, UK Bailey Bridge, Mabey Compact 100 and Acrow 300

Background The Bailey Bridge panel bridge system has been around since WWII. It has been credited as being one of the top 3 technological advancements that allowed the allies to win the war. After ...
135 views

### How do I choose operating parameters for input air to a methane reformer?

I'm interested in controlled oxidation of nickel in a methane reformer with diameter ~3 m and height ~1.5 m. In this reactor, CH4 is converted into H2 and CO, and CO into H2 and CO2 but for this ...
501 views

### Hydraulic siphon spillway entry and exit velocity magnitude and profiles

I am working on the hydraulic seawater flow though a siphon spillway. My task is to determine at a location in front of the spillway the flow velocity and profile when The flow enters the spillway ...
1k views

### Observability using the Discrete Extended Kalman Filter (EKF)

I have built (several) discrete Extended Kalman Filters (EKF). The system model I am building has 9 states, and 10 observations. I see that most of the states converge except one. All except 1-2 of ...
131 views

### Recommended models for mineral liberation in crushers

I'm investigating comminution processes at work, and from my studies I know that there are different breakage models for different modes (Compression, attrition, fracture etc). So far I have only ...
415 views

### External diffusion: calculation of surface concentration

I am struggling a bit with an external diffusion problem. I am trying to calculate the concentration at the surface (as well as surface reaction rate) and would like some help or guidance. Here is ...
2k views

### How to make factory machine hard disk drive more durable? How much its estimate life span?

I wonder how can I make hard disk drive more durable? Specifically, I works in a factory environment. And almost every few months, hard disk drive in some of the factory machine are corrupted, and ...
4k views

### How can “mpg” be high under low engine load?

Let's say a car at 60 mph requires roughly 20 hp to maintain its speed (i.e., to overcome rolling resistance and drag). If this car makes 240 hp and gets about 34 mpg (not too unrealistic), how is it ...
2k views

### How can one calculate the change in heat energy when the specific heat varies with temperature?

Many materials have a specific heat which varies with temperature, especially as the temperature change grows large. How does one calculate the heat energy that an object receives in this case? Can ...
3k views

### Is systems engineer an IT profession or an interdisciplinary field of engineering?

The term Systems Engineer has always interested me as it generally involves many different fields of engineering. Systems Engineer - Interdisciplinary The definition I'm familiar with is usually ...
8k views

### How does pressure change with depth in earth?

I've learned in school that pressure in water changes like $$p(h) = \rho g h$$ where $h$ is depth in meters, $\rho$ is density (e.g. 1000 $\frac{\text{kg}}{\text{m}^3}$ for water) and $g$ is ...
2k views

### How can the alloying materials of recycled steels be separated?

As I know, a very considerable part of the currently processed steels (around half of it) is coming from recycling. But during the steels coming into the recycling process are coming normally from ...
2k views

### Difference in energy consumption between empty fridge and fridge filled with bottles of water

I have about 12 bottles of water. If I want to minimize the energy consumption of my refrigerator, should I put these bottles in the fridge or leave them out?
3k views

### How can a knife cut through butter?

How does anything actually cut anything, since we all know stuff is made up of atoms and molecules, which can't be touched together (It Requires Binding Energy). So how come we see things all around ...
2k views

### Mechanism of gear rotation

Is the smaller gear (pinion) always mounted to the input shaft when meshed with a bigger gear that is mounted on the output shaft? Are there places where the bigger gear drives the smaller gear?
838 views

### Could air-launched space planes reach escape velocities?

Rockets like the Ariane 5 weigh hundreds of tons, but with about 85% of that weight being fuel, the payload fraction is only about 3% (~10-20 tons). Virgin Galactic is building suborbital space ...
134 views

### How is the wattage of an incandescent light fixture determined?

I've seen light fixtures with varying wattage rating. From 30W to 100W even though the actual socket is the same. What is the limiting factor, why can't I put say a 75W bulb in a fixture rated at 50W?...
13k views

### Steel selection for building a trailer

I'm thinking about building another trailer. I've built lots of smaller trailers in the past, but this time I'd like to build myself a small tandem axle gooseneck rated for 7,500 lbs. I am a ...
9k views

### Why are most standard bolt threads single start?

When looking at thread descriptions, one of the basic properties is always the number of thread starts. As far as I could tell, all of the major standard bolt threads are single-start. This includes: ...
427 views

### How is gas flow through (extremely long) pipelines monitored and controlled?

(This is closely linked with measuring the Mach number inside a nozzle but it is not regarding the supersonic flow) Friction and heat transfer have effects on the Mach number of the compressible flow ...
20k views

### What does “$\pm$ 0.5% F.S.” mean?

I've seen it in several data sheets - it is a measure of error of some kind, of course. The problem is I dont know the exact meaning. I've seen it in the context of repeatability, accuracy and ...
1k views

### How do I form a budget for a mechanical research project?

I'm a mechatronics engineering student currently on workplacement. I've put forward a research proposal to develop an improved mechanical gripper used for automated product handling. The company likes ...