Category Archives: Web Site

What happened to the desktop Lab?

As of July, 2022, I am no longer providing downloads of the desktop versions of our software.

After retiring from the university eight years ago, I stopped maintaining the desktop (standalone, executable) versions for several reasons.

The main reason is that web technology has developed to the point that interactive web apps can be written once, then distributed and run on all varieties of smart phones and computers. One important development has been the dramatically increased speed of Javascript in web browsers, which enables fast computation and graphics animation.

Another reason is that I have chosen not to spend the cost in time and money required to update and build desktop executables for multiple operating systems, as the versions of our development tool, LiveCode, and operating systems change.

The source code of our desktop software is posted at our GitHub site.

Please see our Web Labs, for which the source code is also posted at our GitHub site.

Please send us a message letting us know what you think at

Links to external sites open in new browser tabs.

More analysis of files downloaded from RESOURCES

We analyzed the raw log from October 31 through November 11 of 2021, subtracting web bots and spiders.

Of 764 unique users who accessed at least one PDF, only 80 did anything on the site other than access a PDF (view or download).

Two reasons probably contribute to this result: (1) some users are accessing single pages found in a browser search, and (2) some instructors are posting direct links to individual PDFs in the RESOURCES section.

That is easy to do in making reading assignments but deprives students of seeing all the other material on this web site.

I request that instructors post a link to our Home Page with each assignment and encourage students to look around the site.

Maybe even ask students to turn in a response to a question, such as what the conversion of reactant is when the temperature is set to 300 for the home page reactor.

A big THANK YOU to instructors who do this!

Top files downloaded from RESOURCES

We were interested in which notes in the RESOURCES section are being used. The data here are for the month of October, 2021.

We are happy the notes in Resources are being found useful. Please let us know your thoughts via email to

The top 10 countries for download bandwidth are, in order most to least: USA, India, Mexico, Brazil, Canada, Philippines, Japan, Great Britain, Russia, Germany.

Top 20 files accessed (viewed or downloaded):

# Downloads, File
221, CRE Notes 13 – intro to PFRs
217, CRE Notes 7 – data analysis
216, CRE Notes 14 – intro to CSTRs
213, CRE Notes 16 – more reactors
181, CRE Notes 9 – thermal effects
139, CRE Notes 12 – multiple reactions
106, CRE Notes 15 – CSTR thermal effects
104, COCO simulator, Part 1 – flash drum
83, Matlab, material balances
80, CRE Notes 11 – semi-batch
72, GRAD CRE Notes, oregonator description
67, GRAD CRE Notes, Reaction and diffusion in porous catalysts
60, Matlab, array vs matrix ops
54, Matlab, bouncing ball eqns
48, CRE Notes 4 – integration
47, CRE Notes 13-A – methanol reactor model
47, GRAD CRE Notes, ammonia synthesis kinetics
39, Matlab, hex 15_12.txt
38, Control notes, 4. transfer functions
38, GRAD CRE Notes, effectiveness greater than one

The Web Labs are being used each day

We counted the number of runs in each of the Web Labs for the 13.4 days of Mon, 18 Oct 2021 21:16 to Mon, 1 Nov 2021 11:00

The reactor on the Home Page is seeing an average of 45 runs per day.

Lab 7, the Plug Flow Reactor is seeing an average of 30 runs per day during this period. Every Web Lab has been used.

We are happy the Web Labs are being found useful. Please let us know your thoughts via email to

600 runs, Home Page reactor
406 runs, Lab 7, Plug Flow Reactor, including 7 Quiz for this period
271 runs, Lab 9, Hysteresis and multiple steady states in catalytic CSTRs in series
103 runs, Lab 13, Batch reactor, isothermal, nth order reaction
101 runs, Lab 3, Reactor T control with Tj inlet
83 runs, Lab 1, Water Tank Level Control
63 runs, Lab 14, CSTR, isothermal, nth order reaction
52 runs, Lab 15, PFR reactor, isothermal, nth order reaction
47 runs, Lab 5, Bioreactor Control
35 runs, Lab 18, Teddy Token blockchain
22 runs, Lab 000, Artificial Zoo, with the Dragon most popular
16 runs, Lab 00, Pendulum
10 runs, Lab 17, Cryptographic hash
9 runs, Lab 2, Dynamic diffusion and reaction in a porous solid catalyst
8 runs, Lab 8, Plug Flow Reactor + Heat Exchanger
7 runs, Lab FF, Forest fire
6 runs, Lab 0, Swarm of Objects
6 runs, Lab 16, RSA encryption
2 runs, Lab 1A, Level Control, two tanks in series
2 runs, Lab 4, Reactor T control with Tj
2 runs, Lab 6, Heat Exchanger

Evolution of Reactor Lab

Reactor Lab celebrated its 27th anniversary in March 2020. Starting in 2003, the desktop version was integrated with the Internet, with advanced features for that time.

These advanced features included automatic download and installation of updated files for off-line work, a conference (chat) room for discussions within Reactor Lab, and the ability to run process simulations involving local units and units at other locations in the same system. At that time, one could not assume constant connection to the Internet, as we do now. Once, from San Diego, I had a three-way discussion with a person in Michigan and a person in Turkey in the conference room.

I retired from the University of California at San Diego – UCSD – in 2014. Since then, my interest has shifted from the desktop version, which was constructed with LiveCode, to the HTML5-based Web Labs at this site.

This shift has been for a number of reasons, including omnipresent Internet connection in much of the world, almost everyone has access to the web and a web browser without having to download an application file, and the fast speed of Javascript built into web browsers.

That said, desktop apps have advantages over web pages such as saving data files to disk. In Web Labs, one has to go through an extra step to copy text from a popup window and save to a disk file. There are so many features that were built into the desktop Reactor Lab that duplicating them all in HTML5 might not happen.

I used to post standalone application files for Windows and Macintosh. With the evolution of operating systems and the evolution of LiveCode, I no longer wish to make the revisions necessary to build standalones.

However, one can continue to use the desktop Reactor Lab on Windows, Mac, and Linux. This can be done by opening Reactor Lab in LiveCode, version 8.0 or higher. LiveCode can be obtained at Download the free, open-source version of Reactor Lab from my github site at

Instructions for how to do this are posted at the Download tab.

Where are you?

As long as we were teaching, we knew our notes and software were being used by our students. Now that we have retired, we have to analyze our web logs to see who is using the site and software. We are in the process of writing LiveCode scripts to scan through our logs and do some analysis. Here are some preliminary results for the month of February, 2018.

The first objective was to try to purge the logs of all web bots, spiders and crawlers. We were left with 20% of the original lines in the logs. I suspect that the bots/spiders/crawlers are indexing the PDF files in the RESOURCES section, which allows many users to find them in searches. Good in some aspects, but many users might not explore the rest of the site. All the RESOURCES content may be the reason that a search for “ReactorLab” or “Reactor Lab” puts our site at the top of page 1.

We were left with 3200 unique visitors after the purge, or simply “visitors” henceforth (unique IP addresses). This number roughly agrees with the Visitor Maps results in the NOW section. These visitors were from 107 different countries. The top five countries with the most activity were the US, India, Philippines, Ukraine, and the United Kingdom.

Of those 3200 total unique visitors, 2300 visitors from 96 countries used pages in the RESOURCES section of the site: 370 from 56 countries used the Matlab section, 1100 from 74 countries used the undergrad CRE Notes section, and 530 visitors from 66 countries used the Grad CRE section.

There were 59 visitors who downloaded the desktop software, and 86 visitors who ran the desktop software AND went “online.” There were six users of the Web Labs. Again, these numbers are for the month of February, 2018.

So far, I am pleased with what I am finding. I would be delighted to hear directly from you via email to   . Thanks.

Fun to see Visitor Maps

We recently added the Visitor Maps plugin to our About page. We are getting about 50 visitors per day. By clicking the “View more maps in the Visitor Map Viewer” link under the map, you can get versions where you can mouse over the map pins, wait, and get a tool tip showing where the pin is located. Here is a static screen shot:

static screenshot of Visitor Map on Aug 12, 2016

SimzLab added to Download page

An archival copy of SimzLab was added to the Download page. Reactor Lab was removed and the “on line” functions do not work in this copy of SimzLab. This copy does contain working copies of PureWaterLab, the Control Lab, and a heat exchanger simulation.