What is performance: Definition and 258 Discussions

Homework Statement A strait fin fabricated from 2024 AL with k=185w/mK base thickness=3mm, length=15mm. Tb=100C and fluid temp is Tinfinity=20C and h =50 w/m^2K. For the foregoing conditions and a fin of unit width, compare the fin heat rate, efficiency, and volume of a triangular fin...

I am getting a ton of errors trying to compile this. I am including PAPI and ATLAS calls but so far I think those calls are working ok. For each subroutine, I am getting "unclassifiable statement" for the subroutine definition as well as "unexpected implicit none" and "expecting end program...

A micro-instruction sequencing and execution machine has a clock cycle time of 10 ns and a base Cycle Per Instruction (CPI) of 5. The possibility of interrupts and (or) exceptions may happen in the middle of an instruction that must have copies of the values of the registers at the beginning of...

You want to select a gear such that the rpm is low enough to avoid overheating and you want to choose a gear that gives you enough torque for the application. A car is going up a 20% grade at a speed of 60 km/h. Gear ratios: 1st - 3.143:1 2nd - 1.870:1 3rd - 1.235:1 4th - .949:1 5th -...

My laptop has a duel core Intel Centrino processor. Whenever I write programs in C/C++ in Visual Studio and run programs which should execute at full speed only one core seems to be doing anything. Some programs seem to be able to make full use of both cores, is this possible in Visual Studio?

Homework Statement I am simulating an OFDM transceiver using MATLAB. I am trying to investigate the effect of frequency offsets on the system performance by measuring different offsets against their respective bit error rate with a SNR of 10 dB. Homework Equations All equations and...

I was thinking if the strenght of the permanet magnet could be parallel to I , the rate at which the the magnet (or wire) rotates parallel to V & of course the wire resistance would go with R . If there is some type of way to determine the outcome of a generator before building it, starting it...

i always see people carrying a starbucks coffee or bottled tea in library and lectures. My friends said that drinking these can make people feel awake and think faster. Is it true? As they are quite expensive and the taste is quite bitter. Are there other alternative/cheaper ways to boost...

How to plot actual compressor performance on manufacturer" performance chart? Hi all, I have problem on plotting the actual compressor performance on manufacturer" performance chart. Can someone guide me? Please see the attached figure for detailed information. Thanks, EP

Gentlemen and ladies, I have an RF device and an in-line amplifier (specifically an AMMC-6220 - http://www.datasheetcatalog.com/datasheets_pdf/A/M/M/C/AMMC-6220.shtml). Certain units develop gain spikes at the high-freq band. They are in very specific frequency locations, and vary in amplitude...

im doing this eperiment on rollercoasters and i was wondering if loop radius effects the vehicle; like if the loop was to small will it make it through? or if the loop was to big will it make it or just simply fall off? :) THANKYOU

I'm interested in calculating the flight performance of World War One aircraft. The aerofoils can give me the coefficient of lift, we have the engine horsepower and the maximum level speeds. Wingloading can generate the stall speeds. How do I calculate the minimum horse power required for...

a teacher wants to see if the lab helps the student perform better. He took two independent samples, 77 students who attended the lab and 23 who didnt attend the lab. 6 out of 77 that attended the lab said that they had difficulties, 16 out of 23 that didnt attend the lab said that had...

Hello, In Fortran 90, will the performance (in terms of computational efficiency) of the following two be the same. If not, which one will be faster. Please advise with the reasoning: (i) do i = imin,imax do j = jmin,jmax do k = kmin,kmax Several statements (rigorous...

I was wondering, are there significant effects on the performance of a solenoid when the solenoid is inside an external magnetic field? Does it affect the rate at which the magnetic field is established within the solenoid?

Homework Statement Okay, so in my Physics 2(high school) class the instructor gave us a lab without any instructions whatsoever even though we have only been covering electricity for 2 days. The question he posed to us was "What factors affect a battery's performance?" and we have to write up...

what equation would i use to find the max velocity and max alt of a rocket. the probem gave me mass of rocket (g), mass of engine (g), mass of propellant (g), average thrust of engine(Newtons), burn duration of the engine (seconds). i got an example which is massrocket=23,mass...

How can we predict the actual test performance of pump from CFD. I need some formulation/calculation method to predict closure.

I got a small 16inch folding bike weight 13kgs and managed to shed it down to 9kg and working in weight reduction further... eg using hollow shaft at the peddle and using clips at the axles and replacing to 14inch rims and redoing the frame in lighter stainless 201 - these are my next to-do...

I recently got my first job after graduating with a BSME and was upset with my evaluation I received. This is a very small company and I was the first truly entry level person that they hired. I am upset because I was trying so hard, but no matter what, it seemed like I was making the wrong...

I am contemplating a new PC build, but I feel that since I am so neurotic about details, it is not going to happen for quite some time. I need to put a lot more research into it. But for the time being, I would like to maximize the performance I get out of my old Dell dimension. The specs right...

Dear twofish-quant, I found this thread interesting especially since I have a daughter in college, and have friend's whose kids are in the same situation. During a discussion with one of them about achievement, grades, stress, time management, cramming, all nighters, etc... I asked him...

Let's say you have a turbojet shaft that needs sealed. Temperatures and pressures are very high (very). Now let's assume that you don't know squat about seals. Aside from brush and labby seals, what other sealing options exist that can operate at extremely high pressures/temperatures (and...

Hi, I am really struggling for days with this problem. It is about computer architecture Homework Statement One difference between a write-through cache and a write-back cache can be in the time it takes to write. During the first cycle, we detect whether a hit will occur, and during the...

Hello, I am a tactical driving instructor and a precision/stunt driver. For more than 15 years I use high PSI tire inflation method on my family car, tactical training courses or stunt performance cars. Namely, if on the side wall of the tire manufacturer is indicating that maximum PSI 41...

I am attempting to build an intake setup for an engine I'm working on. I currently have a 3" diameter aluminum pipe on the throttle body that just curves off to the side. I would like to try and get some cooler air by routing it down into the bumper. I have access to 2.5" diameter piping. I was...

Good evening all. My question is related to the performance of an electric motor. I am a student in engineering and I just started thinking about this. I have a great idea I need help developing. I would like to know particularly if there is some sort of a formula or graph that helps me...

If I have a designed gear box that needs a motor to run , and according to my calculations the input power for the gear box must be 10 Kw at 10 r.p.s must I chose a motor with the same input specifications ? when I buy a motorwith certain specifications like : 10 kw 3000 R.P.M , does these...

A contractor furnished a performance bond having a face value of $100,000 and a payment bond of $100,000. The contract price was a lump sum of $1,000,000. The contractor had completed 60 percent of the work and had been paid $540,000 by the owner. Then the contractor defaulted, leaving unpaid...

I'm just starting to use MPI in Fortran90 and have some questions on improving performance. At the start of a calculation, I run a stage to distribute all required data to the slave nodes. This is a one-off step, but seems to be taking a long time. The code running on the master node...

I'm still reading the paper, but this appears to be a http://arxiv.org/abs/0906.0022" on the students' response to two different curricula on teaching intro E&M at the undergraduate level. They did this at 4 different well-known universities in the US and arrive at a rather conclusive and clear...

01.http://img2.orkut.com/images/milieu/1/1213787033773/32174292/pt/Zpog0ya.jpg How to post image here Its our rc car driven by 3.2 hpi engine 2 speed transmission system, bell crank steering mechanism , fuel use nitro+mthnol its a two stroke engine two wheel drive question:how to increase...

Hi, I am using Sensored BLDC motors for some robotic movements. I am driving my motors using motor drivers. I am using ball screw mechanism for lifting a pedal up and down. On the pedal, there will be always a very high load, placed on it. Now, my motor can lift up the pedal with my desired...

The problem is: Compare the performance of the forward, backward, and central difference methods for estimating the derivative of the following function: y(x)=e^-xsin(3x). Use 101 points from x = 0 to x = 4. Use a random additive error of +/- 0.01. I understand the process of solving this...

Hi guys, great forum you have here... basically, a couple of years ago, I've gotten involved in the hobby of watercooling computers by adding a radiator, pump and waterblocks on the cpus and other heat sources. well, as I've been researching builds by other folks, i notice that some...

hi, is there a reason that powerpc and itanium have been unable to outperform the x86? apple had the g3, g4, g5 and at times claimed powerpc and risc outforms the pentium, and intel itself bet that itanium epic would outperform the x86, and have lower power consumption and replace the x86...

I finished my co-op this past Feb after working at a major technology company (think Intel, AMD, IBM, HP, etc) in a pretty specialized field. For my end of term student performance report, I received quite a good response from my manager. In all the competency categories, I received an...

Hello, I have 2 24V lead acid batteries in parallel to make a power supply for my circuit. I want to do some drain tests, and plot a curve for % energy remaining vs. time. The load on the battery isn't that large, and I don't want to have to supervise my experiment for 12 hours solid. Im...

PROBLEM 1 (work done by gas) Homework Statement 1. An ideal monatomic gas originally in state A is taken reversibly to state B along the straight-line path shown in the pressure-volume graph. What ist he work done by the gas? A) +12 cal B) +122 cal C) 0 cal D) -110 cal E) +110 cal...

Efficiency is essentially the ratio of what you get to what you put in. COP also seems to represents the same thing (i.e. COP of a refrigerator is Ql / W, which is the amount of heat removed / the amount of work done to remove it). I know efficiency cannot exceed 1, but how come COP can have...

Homework Statement I need to find out the rockets max velocity and max altitude. My teacher gave us an example but everytime i use the stuff we know his answer doesn't match mine. So we know: Rockets mass=23 grams mass of engine=16.2 grams mass of propellant=3.12 average thrust=8 Newtons burn...

What is an optimal CO2 concentration (a range of values or percentages) for maintaining baseline performance among humans? For example, short term exposure to CO2 concentrations less than 5% has negligible impacts on performance (I don't think this is true, it's just an example). If anyone...

Hi. I am designing an experiment focused on radio waves for my experiment and this is the basis of it: Three antenna's will be tested for point to point transmission (VHF): [ 144 MHz ] >>3/4 Wave antenna >>1/4 Wave antenna >>5/8 Antenna (Best Angle of Radiation Usually) These...

i have just finished my undergrad in physics with dismal scores. i really wanted to study physics. i found it exciting and still do. but exams are a real hardle for me. i just have a phobia for them. now i am entering my grad school and for the first time after starting physics i am doubting my...

Hi, I think I have confused myself over the COP of a refrigerator. I have refrigeration system and a certain set of values which enable me to plot a P-s diagram. The refrigerant is R-12. I also have another set of 4 results for varying evaporator pressures, and I have drawn all these cycles...

Lightness and Trouble describe current thinking about the most fundamental physics questions--the underlying nature of space and matter. Ten years ago such books might well have emphasized string efforts in that direction. These books do not. They are in that sense post-string popular accounts...

Hi fellows; we used the gas turbine from solar inc. A catterpillar company model centaur 4502 and 4702.i am resposible for the test cell where the gas turbines engine tests after over hauling.i face some problems.our engines are two shaft the power turbine direct couple with the dynmometer.the...

What are the variables that influence the performance of an internal combustion engine?

Hi, I was trying to analyze the performance of a so called expert stock picker. Can you please check my argument? Are there any holes in my argument? According to the stock picker, out of 15 stocks he picked over his career 10 turned out to be big winners. I made the following argument...

Can someone please explain to me what "Performance Factor" is? I wasn't sure where to post this, but as the title implies I need someone to explain to me what the concept of "performance factor" is. I'm not sure if that's the correct english phrase I'm looking for, but that's how my dictionary...