What is performance: Definition and 258 Discussions

I'm trying to determine the amount of load (power loss) a theoretical engine will suffer from an AC alternator, such as one you would find on an automobile engine, they produce something of 40 amps with 110 volts I believe? To be specific, I'm curious to know how much a theoretical engine would...

Hi I am a student who wants to know what factors apart from environmental factors affect the life and performance of a generator. I think that the load also would affect the life if so How? Also are there any other factors. Do let me know ..thanks

Homework Statement In an ideal refrigeration cycle, the temperature of the condensing vapour is 40oC and the temperature during evaporation is -20oC. Determine the coefficient of performance of this cycle for the working fluids; R12 and ammonia. Homework Equations C.O.Pc = TL/(TH-TL) The...

Hello, I have a few questions regarding acceptance to master's programs in physics. I started undergrad many years younger than my peers (I was 14). Due to a combination of poor discipline and time management skills, family issues, and mental health issues, my performance during my first three...

Hi Guys! I'm doing a conceptual performance calculation and analysis on co-axial rotor UAV helicopter on hover. However, I'm having conflicting results and if anyone can help me, it would be very great. The design constant of the helicopter are as follows: MTOW = 20 kg κ = 1.15 (Induced Power...

Homework Statement Cooling of a food from 293K (20 ⁰C), freezing it at 272K (-1⁰C), and further cooling to 253K (-20 ⁰C); using cooling water rising in temperature from 293K (20 ⁰C) to 303K (30 ⁰C) to accept heat. The specific heat of the unfrozen food is taken as 3.2 kJ/kg K, that of the...

Hi I have uploaded centrifugal compressor performance curve. I want to know how Mass Flow vs Pressure Ratio curve plotted under different efficiency since efficiency is a constant for a compressor. Please help.

I'm frustrated with several of my PCs' performance. The issue may be with their Internet connections, or with other processing issues. Is there some software package that I can run to give me a GUI window showing Internet bandwidth, memory usage, etc, to help me debug the sometimes slow...

Hi all! Now I don't know whether the question I am about to pose is something that can be answered intelligibly. Maybe it is just a case about motivation...but I am not too sure at the moment. My question is: Does mediocre performance in first and second year physics present a possible...

There are two kinds of advice I'd like : On how to make a plan and how to follow it out. On how to actually spend the study time allotted. My daily schedule is something like waking up at about 4. I have till around 6 to study and then I must get ready and reach the bus stand at 6:50. College...

Hi I have data for a two wheel bootstarp air cycle machine used in aircraft environmental control system for air-conditioning under working conditions. The data available (ie mass flow rate, pressure, temperature of bleed air) is for different flight conditions, different altitudes, different...

Hi Guys. This is for my post graduation project. I came across a turbine performance map where the turbine specs are mentioned as GT12, 72 Trim, 0.39 A/R. Now what exactly these terms means. Please help.

This question is slightly related to my other plane, but I didn't want to post in the same thread as I didn't want the other one to get derailed. If I have blueprints for an RC plane, and I scale down everything by a ratio (let's say 1/2), would it still work just as well? Or would it follow...

Dear, I have a confusion related to the attached image which represents the curve performance of centrifugal pumps. My point is, why is the consumed power, on the same pump curve, is increased as the flow increases?! since the logic for me is the opposite at which the consumed power should...

Just saw an interesting topic and was wondering what others thought. How much do you think ones confidence in their ability to learn can effect their ability to learn?

I am currently studying a-levels in physics, maths and chemistry, after a below par performance in my AS levels I am working hard to try and boost up my grades, in lessons I am all okay but once i get to an exam i seem to lose all ability and end up losing lots of marks through silly errors or...

How significant is the effect of tire tread pattern/design on the performance.I searched a lot but could not get any satisfactory answer. I know some designs favour better grip over speed (high rolling resistance), some are better for wet conditions but is the difference in tread design very...

A battery of constant voltage is in series to a conductor that is placed in a changing magnetic field over time, inducing an EMF with a polarity as indicated in the circuit as "Induced EMF(1)", both the battery and the induced EMF(1) are in series as the input voltage to the DC converter, the...

This EJP paper is open access, so you should be able to read it. The conclusion isn't unexpected, because having a "scaffolding" to guide a student through a problem is almost like hand-holding without an instructor being there. I've used this type of questions during quizzes and maybe even...

Hello, For my Master's Project, we are to choose an IMU module to stabilize a platform. You can think of a servo actuated turret, mounted on a Stewart Platform(which will generate the disturbances). The angular position error should be very low and there are both high and low frequency...

Hi, I am in the process of deleting some services ( or at least stopping them from being loaded upon starting up), but I don't want to delete my restore points. Which services will have the effect that their removal will delete restore points? WWGD: What Would Gauss Do? ( If he knew about...

Any ideas much appreciated. Repro steps: Open this: http://jaminweb.com/projs/snakegame.php Change the speed to Fast Go get a couple pieces of food, lengthening your snake a few blocks Notice how it's already moving slower Code...

http://www.sciencedaily.com/releases/2014/11/141125111816.htm?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+sciencedaily%2Fmatter_energy%2Fsolar_energy+%28Solar+Energy+News+--+ScienceDaily%29 Pretty cool use of a mass produced product but how much do you think a Chuck Norris disk...

For finding fan performance curve where better to put static pressure probes - near the surface or near the center of the duct ?

I have two Nvidia GeForce GTX 680's in SLI and was considering saving up some money to buy two GTX 980's and put them in SLI. How much more performance should I expect to see? Based on what I've read, the 980 is more than twice as fast as the Kepler. And would an Intel Core i7 3770K (Ivy...

Hello PF, New to PF, first post! I graduated with a BS in Chemistry in 2010, and I have started my graduate studies in Materials Science. My physics/electrical engineering knowledge is a little shaky, and I am trying to catch up. During group meetings, a lot of graduate students are...

Hello! :) I illustrate my question with a sport betting example: A sport bettor (or an algorithm, or whatever...) make a serie of 5000 wagers on tennis matches at various odds and wins 3800 of those. If we run Chi-test over his bets he gets a score of 12 which means that the chance he got...

Homework Statement What cruise velocity should the aircraft fly to maximize the cruise range? Aircraft mass (excluding fuel), m0= 14000kg Mass of fuel, mf = 2500kg Specific fuel consumption of aircraft engine, sfc = 2.8\times10-5 kg/N/s Drag polar, CD = 0.02+0.08CL^2 Planform area of...

Homework Statement An ideal gas adiabatic coefficient γ is submitted to the ABCA cycle of fig, where AB is a line segment.. a) Calculate the income. b) Show that it is smaller than the yield of a Carnot cycle operating between the same temperature extremes. this is my attempt...

Dear All, I am estimating a future problem while still in erection phase for 60 MW steam turbine. I may need your help to estimate a solution. Due to some reason my process heater is not able to generate steam at the desired pressure (other parameters including Temperature and Flow rate...

1. Hi, the question is "A simple D.C motor has been constructed using one pole pair having a square surface of 6cm × 6cm and produced a flux of 18mWb. The commutator has 4 segments, which allows for two simple loops to be connected. Two brushes are used with the positive applied to the brush...

Homework Statement Please see the attachment for the question, thanks Homework Equations Also given in attachment The Attempt at a Solution After eliminating A, I have a w2 term which I cannot eliminate and my l term is cubed and my ρ term is not squared. If anyone can guide me through...

Hello, I am an engineering student and finding that I am overwhelmed and frustrated. Between some of the exams being basically impossible, quizzes that are extremely hard, mind numbingly difficult labs with prelab sections, and the non-stop barrage of problem sets that are also difficult with...

For a University project I need to somehow model the effective performance of a ground grid in the event of a fault caused by a lightning strike. We would need to prepare different test cases for different sizes and grid configurations in order to carry out different analysis and find the...

Hi all, I am a graduate student of Nuclear Engineering studying fuel and cladding performance during different conditions in the reactor. I have access to FRAPTRAN/FRAPCON codes from frapcon.labworks.org. Being a newbie, I am quite unfamiliar as to how it all works. So is it ok if I...

Homework Statement Does Coefficient of Performance for refrigeration cycle depend on refrigerant used? In reference to vapor-compression cycle Homework Equations COP = \frac{1}{\frac{T_{H}}{T_{L}}-1} The Attempt at a Solution I am split in my answer to this question. I...

https://www.youtube.com/watch?v=UFpe3Up9T_g

Hello All, i am working on an HHO dry-cell project for which i need to decide upon the sensors to be used in monitoring the process parameters. 1. some sensor for monitoring and displaying the electrolyte level in the bubbler during experiment. 2. some sensor for monitoring the...

hi all; actually i have done an experiment using die sinking EDM using one copper electrode and three different work piece material copper aluminum and stainless steel to perform a comparative study in term of MRR, TWR and surface roughness. i used ( pulse current 8, 12, 16, 20 and 24 Am... the...

Hey guys. I was studying up jet-engines and their performances with varying ambient temperatures and found myself stuck on something that is probably very trivial. What I've read online and in my notes is all generally the same - that as temperature falls air density rises and as such more...

Hi I am having difficulty explaining to my mechanical engineering supervisors the following: When a pumped storage unit is in generation mode, synchronised to the grid and in steady state and the guide vanes/wicket gates are opened more to allow more water flow and therefore more power...

Can anyone elobrate what is the (specification, durability, safety, and performance ) for band brakes used in conveyor system...??Your help is much appreciated. Thank you.

Homework Statement 1. We have a set of observations on p = 100 features. The observations are uniformly distributed on each feature, and each feature ranges in value from 0 to 1. We wish to predict a test observation’s response using observations within the 10 % of each feature’s range that is...

How would the CPU, RAM and disk storage of a Database server affect the performance of the Database?

I have a sailboat with 2 solar panels installed. They work well, except at the end of the season when the days are shorter, the nights are longer and the sun is lower, so I built a mechanism to tilt and rotate the panels so that they could be pointed directly at the sun. With low sun angles I...

Problem statement, I am calculating the time it takes for my motorcycle to reach 55 miles per hour, through its engine Horsepower, Torque, transmission gearing, and sprocket gearing.(chain driven) I am using the equations: F=[mass/g]*[dV/dt] dt=[mass/g]*[dV/F] t=∫[mass/g]*[dV/F]...

I have a set up which is basically a small wind tunnel (single rectangular channel) with an axial fan at the inlet. The experiment is testing the effect of various shaped "shrouds" that constrict flow around an inductor to improve the convective cooling. I have heat transfer coefficients and...

I'd like to know the dimensionless parameters affecting a counter-flow induced draft cooling tower's performance, or if someone could direct me to an adequate resource . I'd also appreciate if I could be directed to some good comprehensive resources on cooling tower design Thanks guys

Just recently my laptop (6 years old now) is starting to deteriorate in performance quite a bit. Applications are running slow, shockwave applications embedded in browsers are crashing from time to time. There's quite a bit of rubbish that has been installed on the machine over the years that I...

I was told that performance gains using memory above 1600MHz in enthusiast desktops is very small and unnoticeable, and is only useful when overclocking. This has something to do with "JDEC" what is JDEC?