I have decided to restructure the PE review course options which also reduced the course pricing.
The Basic Course now is strictly "do it yourself". The student forum is not included. However, the instantly graded online quizzes that are included will provide you the needed check on your progress and indicate areas where additional practice might be needed. This course option is a very competitive option that is economical in both cost and study time.
The online office hours have been removed from the Premium Course. In their place, I will participate in the online forum, providing comments or explanatory attachments as needed. I made this change for a couple of reasons. First, the online office hours were restrictive for student participation due to the time zone problem and student work schedules. Second, a fixed office hour period may not allow enough time to address all students' questions. The price has been reduced because of the removal of the online office hours. The flexibility of coaching via the forum is a "win-win" for both students and me.
The VIP course is unchanged except the price has been reduced due to the changes in the Premium Course price and content.
Click on the button below to go to the updated Course Pricing page.
I am on track and on schedule to have the Chemical PE Review Course ready for July 1 of this year. Now is the time for people wanting to take the exam in October to get started with preliminary requirements.
Explore your state requirements
The first task is to review the application requirements for your state. You may find that information on the website of your state's engineering licensing board. The National Society of Professional Engineers website, nspe.org, provides links to websites of the state boards. Use the button below to go to nspe.org.
Pass the Fundamentals of Engineering Exam
Before you can apply to your state board to take the final, PE Exam, you must have already passed the Fundamentals of Engineering Exam. You may take this exam year-around and you may take it more than once. It is administered by NCEES nationwide at their contracted computer based testing sites. They offer preparation materials on their website at a modest cost. Their website also tells how you sign up to take the test and gives the test locations. This test shouldn't require a lot of study preparation beyond the sample exam from NCEES.
A few days ago I updated the Mathcad files that link to the Prode Physical Properties (PPP) program. In this post, I want to discuss the different kinds of PPP updates and how they affect the Mathcad updates.
Three kinds of PPP updates
When Prode updates their program, there are three kinds of files that might be changed:
What PPP update requires an update of the Mathcad-PPP files?
Item 2 is the only update that affects the prode.dll and the Test-PPP.xmcd files.
What happens when you download a new version of PPP?
When you install a new version of PPP, the install program places the latest version of ppp.dll in the appropriate system folder, and it places the reduced chem.dat file for non-subscribers in the Program Data/prode folder. If item 3 was not updated, a user with a paid license then copies their old, full chem.dat file into that folder, along with their old license.dat file. If item 3 is updated, licensed users receive an email with the new chem files and a new license.dat file. If the ppp.lib file was updated, it will arrive with the download, but that file is not used directly by Mathcad users. Instead, I use that file to create the prode.dll files for Mathcad and Prime.
Can you run a new version of PPP without a corresponding update of the prode.dll?
Yes you can! Any changes to ppp.dll and chem.dat are unaffected by the library functions. Until the prode.dll for Mathcad is updated, your old programs can still be used with the old calling formats. Any new functions in the new library will not be available.
When you update with the prode.dll found on this site, will your old programs still run?
That depends upon whether your program uses a function that has changed. For example, the recent update changed the mc_MixF function because the ppp.lib file changed the MixF function. The old version of that function would produce an error. When you see the error, you should check the Test-PPP.xmcd file to see the new calling format and a description of the arguments.
Another way to check for all of the function changes is to install the new prode.dll and then run the old Test-PPP.xmcd file. All functions that have changed will have errors and be in red. Then look in the new Test-PPP.xmcd file for the new formats.
My motivation for this post
Basically, I feel a little guilty for waiting so long to update the prode.dll and test files for the PPP version 1.2c3. However, I wanted to explain that the delay wasn't preventing users from running Mathcad-Prode with new chemical data or preventing them from running completely. All that was delayed was use of a new version of MixF.
If you are unfamiliar with PPP...
I think the Mathcad-PPP combination is one of the most cost effective general purpose computation tools for chemical engineers. The archives of this blog demonstrate many examples of its use. To see the extensive, yet easy to use functions, and the kind of data available, you may download the pdf file of the Test-PPP.xmcd. Click on the button below to go to the page where that file resides.
Yes, another PE Exam review course. However, I think you will find my course to be different from the others. My main goals for the course are (1) to give you the practice you need to pass the exam, and (2) to do that in the least painful manner (i.e. shortest study time).
The launch of the course is targeted for the Oct 2017 exam. Until then, please register for the Free Trial using the "Log In/Register" menu item. You may also read more about the course starting at my Home page.
I am currently working on a large project so I have closed the online collaboration service at this time.
I have decided to start a collaboration, consulting, and tutoring service. Preparations are nearly completed. I have the collaboration and scheduling software working and tested. I am waiting on a new laptop with better freehand sketching capability. When that arrives I will have to load software, transfer licenses, etc. and retest.
When I'm ready, I will announce in the blog and on my site Home page. I hope to launch in mid-May.
I have given serious thought to Carlo's idea of creating a site where the readers collaborate on solving their problems. I looked into whiteboard and screen sharing software and websites and actually picked out the ones I would use. I even considered the idea of asking for donations instead of subscriptions. However, I have decided not to pursue the idea of an open collaboration site for the following reasons.
Keeping it clean
I read that about half of the edits to Wikipedia are just to remove objectionable and inappropriate material...racist, political, pornographic, or advertising. I trust that my current audience would not participate in these malicious activities, but it wouldn't take long for the trolls to find the site and exploit it's openness.
One of the whiteboards gave an example of what can happen. They provide a free board open to the public. One, or more, of the users posted objectionable material, so the company banned the suspected user. However, the user would plead that one of the other users was the offender. The company had no way of telling which user was guilty when multiple users were online.
Another example is the Chemical Reaction Engineering Group on LinkedIn. So called market researchers were posting advertisements as fast as the group leader could delete them. He finally had to start approving every submission, just as I have been doing with comments to this blog.
I haven't found a whiteboard that gives each user the ability to erase or delete only their contributions. Thus, a troll, after having his work deleted repeatedly, might start deleting the work of others.
My current thinking...
The above comments were about an open format. The closed format below should prevent the problems mentioned.
A traditional whiteboard is somewhat limited in capability for engineering problems. Thus, I think it would be great to use my Mathcad/Prode Properties combination to work on problems. Here's how I think it would work.
Mathcad and Prode experience
The above proposal should work great for students who already use Mathcad. For others, we could try the following approach.
I have a couple of pdf documents that show the basics of Mathcad. I could make these freely available on my website. Students could read these to become familiar with data entry and the Mathcad conventions. Then, I could set up free sessions with Join.me to do some hands on practice before the first paid session.
When I share the screen with someone using a non-USA keyboard mapping, the input will not be completely correct. If that happens, the student can tell me what he/she meant (via audio or chat) and I can retype it.
The sessions will all be live. Thus, large time differences between me and the students could present a scheduling problem.
You could "stump me". I don't have instant recall with all subjects. To avoid that, students should provide a brief description of the problem or subject prior to the session. However, if I'm still unable to coach you to a solution, we can terminate the session and reconvene at a later time. This would give me some time to study the problem.
I think this concept is unique. There are entire ChE courses on the web, as well as free video lectures. However, I haven't seen anything that involves the kind of collaboration and interactive computing and problem solving with a professional coach that I have outlined above. I should also point out that the above approach could be used for math tutoring. I have a minor in math and I have used calculus and numerical methods for solving ODEs and PDEs throughout my career.
Are you interested?
Readers of this blog have indicated that they have learned a lot from the blog. This has prompted me to consider starting a tutoring business, with a focus on chemical engineering and college level math and sciences courses. Before I spend time and money getting the needed tools together, I would like to see if there is sufficient interest from my blog readers.
The tutoring format would probably involve online chat or audio/visual conversation, screen sharing, an interactive whiteboard and document examples. If the student has a tablet input capability, the interactive whiteboard could also be collaborative, i.e. two-way input. The tablet input could be provided by a simple tablet device for about $70, or by a tablet computer.
I also wonder if there is interest in using the above tools for online consultation with practicing engineers. Consultation could involve project planning, follow-up review, and report review.
If you think you might be interested in tutoring or online consultation, please use the "Contact Me" tab on the site menu on the left. There will be no obligation to you. If you wish, please indicate what subject(s) and level (undergrad or graduate) are of interest to you.
I hope to hear from you!
The column routine is not robust, nor is it very efficient. It appears that the existence of multiple solutions for the rx_flash solve block is the source of the problems.
In the column routine, each stage is solved in sequence and then the results for an iteration are compared with those from the previous iteration. For the next iteration, I have tried relaxed direct substitution, Wegstein, and generalized dominant eigenvalue methods. I have also tried different guesses for the rx_flash routine. Solutions can be obtained for some, but not all cases. When solutions were obtained, the computation time was on the order of one hour.
It is possible that the rate based method can avoid the multiple solution problem. It may be awhile before I have something new to post.
I have the column routine working, but I am still testing various cases. Since it may not be in its final form, I am delaying its presentation. Instead, this post will provide some tips on programming to avoid errors.
Avoiding unrealistic values
Numerical methods may momentarily produce unrealistic values such as zero or negative flows. Such results can then upset the algorithm producing further errors such as imaginary numbers or division by zero. Since most processes can't produce a true zero concentration, for example, the error can be avoided by limiting the variable to a very small finite number.
Using Mathcad's "on error" function
The "on error" function can be used to avoid termination due to error. In the example below, the normal assignment for x4_new is the one on the right of "on error". If that calculation results in an error then the alternative assignment on the left is used.
In the stage_N routine shown in the previous post, I had a statement that created a divide by zero error. The first statement below was the original version. The error occurred due to to the first term in the denominator. The problem was corrected by multiplying the numerator and denominator by the "out" variable. The improved version is the second statement.