Lowyat.NET: Latest topics by Ultimatheum

Help with Fluid Mechanics

Ultimatheum — Fri, 05 Feb 2016 15:45:17 +0800

A reverse-osmosis unit for purifying brackish water has about 900,000 hollow fibers that permit the diffusion of water but reject most of the salt. The fibers are 85 micrometer in outside diameter, 42 micrometer in inside diameter, and about 3 ft long. The average flow through the tubes is 2000 gal of water ever 24 hours when the feed pressure is 400 psig. What is the pressure drop across the unit from the feed end to the discharge end.

If anyone can help me walk through this problem, it would be much appreciated. Thanks

American hand carry size limit

Ultimatheum — Thu, 30 Jul 2015 00:48:39 +0800

I'm travelling to the States for the first time, and I'm planning to bring the biggest hand carry allowed. There's this bag that I found in Universal Travellers, the brand is Airways, that I really really like but the size is 20. Asking the salesman they said that American's limit is 18 (and they dont sell 18). After looking around the internet, the limit differs by airline (and I do not know what airline am I going to take yet). So anyone can give advice on the size allowance of hand carry I should bring? Should i take the

TL;DR version: What's the size for hand carry luggage that I should bring to the States?

Need some help with integration questions

Ultimatheum — Thu, 07 Aug 2014 21:40:20 +0800

I've been trying hard to do these questions. Will be really happy if anyone of you can help guide me through them. Not the full working, just what to do to get the answer (partial fraction, then by substitution, then.... etc.)

The first one is integrate 1/(4-9x^2)^2 from 0 to 1/3

The second one is integral of 1/((x)(x^2+x+1)

Thank you very much in advance

Help me answer this D:

Ultimatheum — Thu, 01 Aug 2013 08:28:03 +0800

A friend of mine asked me to teach her how to solve this question. Unfortunately, I don't think I've learnt how to solve (we're on a different course). But being the math geek that I am, I am just not satisfied looking at the question left unanswered. So, to put the question simply,

exp(2x) = 3 - exp(-x)

[exp(2x) = e^2x right??]

I tried substituting y=exp(x) to make the equation easier to solve which I ended up having a cubic equation, which I have no idea at all how to solve except by using the calculator. And also, if I'm not mistaken, there's only 1 answer for the question and cubic equations will give you three possible answers. Correct me if I'm mistaken about this question having only 1 answer.

I also tried modifying the equation using ln function, but I ended up having ln[3 - exp(-x)] in which, I'm almost absolutely positive that there is no way of expanding, simplifying, etc. At least, for my level anyway.

Am I missing something? Cause I have a tendency to miss the simplest way of solving mathematical problems. Is there a different approach to answering this question? This comes from the matriculation syllabus but I am not sure which chapter. Functions I guess, cause originally the question got f(x) and stuff.

For my Mathematics, I am currently studying Pre-Calculus (Foundation Level) but we haven't started learning functions yet. So... Yeah ~

Help me satisfy mathematical-geek needs ~

Questions regarding PSU

Ultimatheum — Sun, 31 Mar 2013 18:25:50 +0800

When I tried to turn on my PC, I heard a small noise (boom). Suspecting that the PSU blew, I tried checking it and found that it smells burnt, which I think is a clear indication that the PSU is fried already. Then I found out that the voltage setting whatever thing is set to 120V (well, it's actually 115V) instead of 240V that our beloved country is using (but the other setting here is written 230V. I dunno why). Oh, and the PSU is a Gigabyte Power Rock 390W.

So, can the PSU still be fixed or do I need to replace it? If the PSU can still be fixed, is it advisable to fix it myself, considering I'm not a tech geek? If I need to replace it, is it also advisable for me to replace it myself? Should I buy the same model of PSU or should I go for some other models? If buying other models, how do I know if it's the correct power supply to buy? And the most important thing, are my motherboard and it's other components (CPU, RAM, etc.) are still safe?

P.S Sorry for the lots of question

Is there an alternative way to answer this?

Ultimatheum — Wed, 09 Jan 2013 18:06:29 +0800

So, a friend of mine challenged me to answer this question that they got during their lectures.

|x-5|=|2x+6|-1

I was able to answer the question (0 or -12), but I solved it by sketching a graph for the equations at both hand sides and find the x-coordinate of its intersections. I don't know how to modify the equations so that I can calculate the values of x without drawing any graphs or whatsoever.

Suitable A-Level book replacemens?

Ultimatheum — Sun, 06 Jan 2013 22:21:48 +0800

I really don't know a suitable topic for this question bit here goes... I saw some of my seniors at my place selling their old books to the junior taking A-Levels. The problem is that some of them are actually selling STPM reference books... They said that it's suitable for A-Levels, perhaps even better actually... Quoting one of them, they said "there is nothing that you can find in the a level books that u actually cant find in the stpm books". So yeah... Any comments??

How to get over your fears of something?

Ultimatheum — Thu, 27 Dec 2012 02:34:24 +0800

I don't really know where's the suitable place to post this thread but I guess this will do (sorry xD).

Anyway, back when I was a kid, I had this one very bad experience with dogs which kinda affects me until today. I'm scared of them. All of them. Even the cutest, little puppies TT^TT

Just now I was walking back to home. My neighborhood pretty much has a lot of stray dogs. And one of them nearly attacked me. And when I arrived home, my legs were still shaking xD

Once I sleepover at my friend's house. And he has this very large and scary looking dog. My mum picked me up at his house early (when he was still asleep). So I went downstairs and found out that his dog was there. And he jumped to me and I had practically no where to run TT^TT. Turns out he didn't want to eat me, just want to play with me (and say goodbye I guess? xD). But I'm still freaked out back then =,=

Also another incident where I was hanging out at my friends house, playing his newly bought PS3 (back then when it was first released). Syok2 men suddenly his puppies went and played with me and I was scared shitless. Yes, as I've said, even the cutest, little puppies TT^TT

Since I can't really sleep right now and in the mood to chat... Anyone? xD

Few questions about A-level and scholarships

Ultimatheum — Fri, 21 Dec 2012 01:43:17 +0800

I'm planning to take A-level (january intake) while waiting for my SPM result to come out, mainly because I'm not that confident about how my SPM will turn out, so I decided to work my way from A-level. But from asking a lot of people and their opinion, I am not so sure about getting a scholarship from A-level (my mother can sponsor me to take A-level, but I'm not sure if we can afford anything beyond that) mainly because most of the scholarships here in Malaysia are offered based on your SPM/STPM, etc. results. So, is there any sponsorship bodies that can give u scholarship (or convertible loan??) based on the A-level that I got?

Second question, while I'm on my A-level, then suddenly my SPM went seriously well (chances are low with that) and I got scholarship offers to continue studying elsewhere for a foundation > degree, is it possible to request permission that I finish my A-levels first? Cause I dont really want to leave halfway through. Do you guys have any information regarding this matter?

Thirdly, I really want to continue my studies in the US (personal reasons). But based from what I know, you need to take SAT to get into the universities in the US. So, is there a way for me to study in the US based on my A-level and not my SAT? If not, is it a good idea to study the SAT syllabus by myself and taking the test while I'm studying for my A-level too? It'll be a challenge but it's a challenge I'm dare to take (hopefully I won't regret it though). But I guess I still need a scholarship to go to the US cause the studying cost alone costs approx. RM200k++ and I'm not sure if I went through this kind of path, will there be a sponsoring body even willing to give me a scholarship =,=

I tried to do my homework (research) about every questions that I have in my mind but unfortunately, I can't really find all of the answers... So, your help/advice are much appreciated. Thanks in advance ~