by Elad SalomonsPosted on Posted in EPANET related — 5 Comments ↓

EPANet 3 is due sometime next year and it will probably be the last version supported by the US EPA. Last year, a proposal was made at the 2009 EWRI conference in Kansas City to establish an Open Source Project for EPANet. About two weeks ago, at the WDSA 2010 conference held in the Tucson AZ, Lew Rossman and Kobus van Zyl raised the issue again. During the conference I talked with a few people and got a few opinions, all of them positive I must say. There are a number of issues that needs to be resolved before this kind of project is initiated and in this post I will try to present my views.

Kobus van Zyl at WDSA 2010

Kobus van Zyl at WDSA 2010

I’m all for open source as I have been involved for a few year now with an open source project called WordPress. WordPress is the software that runs this blog and it is used by millions of people all around the world. I have been a part of the Israeli WordPress community by contributing some patches and helping with localization. Earlier this month we held the third WordPress user conference in Israel called WordCamp. All is done by volunteers for the community.

What is Open Source?

Many people think of open source, or free software, as a matter of price, a software that is given for free.  Actually it has nothing to do with price but with liberty. To understand the concept, one should think of “free” as in “free speech”, not as in “free beer”. Usually it is said that users should have four essential freedoms (source: The free software definition):

  • The freedom to run the program, for any purpose (freedom 0).
  • The freedom to study how the program works, and change it to make it do what you wish (freedom 1). Access to the source code is a precondition for this.
  • The freedom to redistribute copies so you can help your neighbor (freedom 2).
  • The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

Organization

An open source project is usually managed online over the Internet and is started with a small group of people that expands as time goes by. The community is self-organizing with almost no official organization. The most common case is that the majority of the community are users and not contributers. The group of contributers divide between core developers, beta-testers, documenters and many people who reports bugs and make suggestions. In most cases, the small core team have the final word regarding what will go in the program and what will not. In the case in which part of the community thinks differently than the core team they may create a “fork” and form a new project (remember that its open source and anyone has the right to do so). However, this is a rare case as the threat of “forkability” is one of the things which holds the community together (Producing Open Source Software by Karl Fogel):

The indispensable ingredient that binds developers together on a free software project, and makes them willing to compromise when necessary, is the code’s forkability: the ability of anyone to take a copy of the source code and use it to start a competing project, known as a fork. The paradoxical thing is that the possibility of forks is usually a much greater force in free software projects than actual forks, which are very rare. Because a fork is bad for everyone, the more serious the threat of a fork becomes, the more willing people are to compromise to avoid it.

In many cases there is one person who holds the “keys” for the project. Since the project is managed online it “lives” on a web server. Currently EPANet is hosted on the EPA’s servers and they control it. When the project will move to a new “home” it will be hosted on a different server which is controlled by some else. At any given time there is only one entity that controls a server. But, no worries. Remember forkability?

A few technicalities

A project is hosted on a web site that should include at least two elements: a version control tool to allow management of the source code and a bug tracking tool. The tools that the WordPress project uses are trac and SVN which are also open source projects. These are self-hosted tools but there are many hosted services like SourceForge and Google Code which ease the project’s management burdens. To get an idea of what these systems offer look at WordPress versions page, the software timeline, the bugs tickets and a small change to the code. In addition to these two tools the community may use a mailing list, support forums, chat rooms, IRC and even, god forbid, face-to-face meetings.

Using a self-hosted solution allows more control on everything. However, with authority comes responsibility. For the self-hosted option the project will need someone to manage the hosting server, keep all software updated, make backups and more. This is a responsibility and also comes with a cost. I think that the EPANet project should start with a hosted solution like Google Code and if\when it grows the community may consider moving to the self-hosted option.

Scope of the software

EPANet is not very different from other projects. Lew reveled that in the first 8 month of 2010 EPANet was downloaded about 20,000 times! What we can learn from this number is that the vast majority of EPANet users are people who use EPANet’s graphical user interface (GUI) and not software developers who uses the programmer’s toolkit or directly use the source code. EPANet is somewhat unique in the fact that it is built from two sub-programs: the hydraulic\quality engine and the GUI. While the first component is most important mainly to the research community the latter is used by most of the program users. I think that EPANet, as an open source project, must include both components (engine and GUI).

License

EPANet was developed by the US EPA. As such, it is a public domain software that may be freely copied and distributed. In other words there is absolutely no ownership. As strange as it may sound, anyone may download the program and sell it as it is. Yes, that’s right, sell it. However, open source is not about money, its about liberty (as explained above).

Each open source project usually have a license and there are plenty of them. There are a few licenses that are popular and widely used or with strong communities: Apache, BSD, GPL, LGPL, MIT and a few more. There is no need to go into each of them and explain the differences as in our case it is enough to consider the GPL and MIT licenses. The MIT license is one of the most simple ones. It actually states that anyone is entitled to do whatever they want with the software with the exception that the authors can’t be held liable in any case. The GPL license is much more complicated but the main difference is that when one redistribute the program, or any derivative of the program, he must do that under the same license. For example, let us consider the case that one would add a new feature to EPANet, like a new valve type, compile the code and sells it to a third party. In both licenses he has the right to do so. However, with GPL, since the new software is a derivative of the original, it is also licensed under GPL. And according to the license the third party must be granted the right to change the code and redistribute it thus he must have access to the source code. I guess that by now you understand the main difference: it would be difficult to sell proprietary software based on a GPLed license EPANet.

If the community would like to allow proprietary software based on EPANet then the MIT license is the way to go. While I was in Tucson I had a chat with a few people on this subject. Some, mainly from the academic research community, said that they would not feel right contributing to the project if commercial companies would be able to make money from their work and not give back to the community. Unfortunately I didn’t have the time to discuss this subject with the corporate people but I will try to get their response. I’m not a lawyer but there are legal and practical ways around this. I think that the project should start with the MIT license and see what understanding may be achieved later on with the big companies.

The case of CWSNet

A few days before the WDSA 2010 conference Dragan Savic announced via the EPANet user’s list the availability of a new open-source, object oriented, library for water distribution system modelling named CWSNet. Zoran Kapelan presented the library at the conference and it seems that it performs very similarly to EPANet but still somewhat slower with large networks. The main advantage of CWSNet is the fact that is object oriented and simplifies the understanding of the code. An example given by the CWSNet authors to show the need for an object oriented library has to do with matrix representation:

Another problem in the design of EPANET is that the items that are used in various parts of the hydraulic computation (such as the matrix representation) do not have a specific interface. For example, the matrix that represents the linear systems of equations is accessed directly by the various methods, i.e. these methods know how the matrix is represented in the memory. Therefore, if a programmer needs to change the internal representation of the matrix, he or she needs to change all the methods that interact with it.

I think that in the long run it would be better if EPANet would be object oriented so the understanding of the code would be much more simple and it would be easy to replace software components. This structure have an additional benefit license wise, as it would be much more easier to include GPLed components in the MIT licensed project. Don’t get me wrong, I think Lew’s code is brilliant. I still use code snippets from the Visual Basic version on EPANet 1.0.

CWSNet awarded at WDSA 2010

CWSNet awarded at WDSA 2010

The introduction of CWSNet, a few days before the conference, seemed to spark a debate among the participants. At one moment it looked like its the Europeans against the Americans. I may got it wring but as I understand it, Lew wants to stay with the current structure for EPANet and not move to an object oriented structure. I think that for version 3.0 this is the way to go as CWSNet is still young, hadn’t been tested and used by the community and currently does not include the water quality engine nor the GUI. A lot of work is needed to bring it to where EPANet currently stands. Once version 3.0 is released and the community takes over a process should be made to merge the work done in CWSNet into the project.

How to proceed?

It may take up to one year for EPANet 3.0 to be released and I have no doubt that the open source project should officially start from that point. However, things may be done in the meanwhile. It is up to the US EPA and Lew Rossman to decide what will be included in version 3.0 and hope this decision would be made soon. Another decision is what will be the GUI development environment – Java or C# (my impression was that it’s going to be Java).

Once these decisions are made I hope Lew will be able to release an alpha version as soon as possible. It does not really matter how raw is this version and how many bugs there are. This alpha version is not to be used by the general public but should be used to set up the open source development environment (Google Code would make a good option). Once the environment is set up people from all over the world could start and learn how to work with it. How to make suggestions, report bugs, suggest code patches and more. If Lew could release also a beta version it would be even better. After the final release of version 3.0 the new code would be uploaded and the community will take it from there.

Conclusions

  • The EPANet project should start with a hosted solution like Google Code.
  • The project must include the core engine and the GUI.
  • At first the MIT license should be selected.
  • Jim Uber suggested that a new name will be selected for the project. This is an option but the community must make sure that the fiasco of the epanet.com domain name will not return.
  • Object oriented structure should be introduced in steps using the work done with CWSNet once the open source project gets going.
  • An alpha version of EPANet 3.0 is essential to set up the open source environment.
Tagged with: , , , ,

by Elad SalomonsPosted on Posted in EPANET related — 46 Comments ↓

During the WDSA2010 conference, held in Tucson AZ, Lew Rossman gave a sneak peek into the future version of EPANet. It might be called 2.1 or 3.0 and it scheduled to be released probably next year. This will be the last release of EPANet by the US EPA! The following writeup is based on Lew’s paper and presentation.

Lew Rossman at WDSA 2010

Lew Rossman at WDSA 2010

Enhancements to the computational engine

  • The simple Euler scheme used in EPANET 2.0 to update tank levels independently of each other between the time steps of an extended period simulation is being replaced by Todini’s recent extension to the Global Gradient algorithm. This produces a much more stable solution for water levels in hydraulically coupled tanks without having to revert to very small time steps.
  • The flow-based convergence criterion used to solve the network hydraulic equations is being replaced by a head-based one. This will provide higher accuracy in satisfying the head loss equation for each pipe once a solution has been found.
  • To avoid the hydraulic solution matrix from becoming ill-conditioned when there are zero-flow or low resistance pipes EPANET 3.0 employs the simple regularization scheme suggested by Elhay and Simpson to adjust very low gradients of head loss with respect to flow.
  • Two options are being concidered as replacements for the 1980’s vintage sparse matrix solver used in EPANET 2.0.
  • A pressure-deficient hydraulic analysis can be run using Todini’s three-stage approach to identify nodes where there is insufficient pressure available to meet required demands and to determine the actual demand that can be delivered at the available pressure. This option avoids the negative pressure results that can sometimes occur when running a standard hydraulic analysis.
  • Pressure-dependent demand analysis is being added as another option in EPANET.
  • An Altitude control valve (ACV) is being added to the types of control valves that EPANET can model. The “setting” parameter for this type of valve is a user-supplied curve that determines the valve’s head loss coefficient as a function of distance below full depth.
  • Cubic polynomials can now be used for pump head and efficiency curves and pump efficiency curves and power calculations can now be scaled for pump speed.
  • Users can define both regular and irregular time patterns for altering demands and controlling pumps and valve settings within extended period simulations. Each regular time pattern can have its own time period while irregular patterns can use a set of variable periods that change over time.

Enhancements to the water quality calculations

  • The equations developed by Sandia National Laboratories (Ho and O’Rear) that model incomplete mixing at 4-way junctions are being incorporated as an option in EPANET 3.0.
  • Longitudinal dispersion of solutes within the bulk flow under laminar flow conditions (Axworthy and Karney) is being added to EPANET’s transport equations. This will necessitate switching the laminar flow pipes from using variable-sized volume segments to uniform-sized ones, reminiscent of the Discrete Volume Element method used back with EPANET 1.1.
  • The reaction and transport phases of the water quality computations will be handled using parallel threads to take advantage of the multiple core processors available on today’s personal computers and thus provide a significant computational speed-up. Using parallel threads shows a decrease up to 50% in running time with 8 cores.
  • Several additional single species reaction mechanisms are being added to those already contained in EPANET. These include: dissolution reactions, temperature modeling, source-weighted reaction coefficients.

Programmer’s Toolkit

Additional functions are being added to the EPANET 3.0 Programmer’s Toolkit. These include functions that allow one to work with a node’s demand categories, allow one to retrieve the water quality within a link, and determine if a portion of the network is disconnected from any water source or if any two nodes are connected through a path of open links.

Windows graphical user interface

The interface for EPANET 2.0 was written in Delphi. To enable greater access for interested third parties to review and modify the EPANET GUI it was decided to re-write it in a language for which free compilers and other development tools are available. A prototype was written in Java which is platform independent as can be seen in the following image that shows EPANet 3.0 under Ubuntu Linux. C# .NET is also being considered as an option for the GUI.

The Java prototype of the EPANET 3.0 GUI running under Ubuntu Linux

The EPANET 3.0 GUI will also provide for a linkage with the EPANET multi-species modeling extension. A new option that might be implemented is the option to insert pumps and valves as nodes rather than links. This option will be of interest to those how use GIS data to build hydraulic models.

Pumps and valves as nodes

Pumps and valves as nodes

Tagged with: , , , , ,

by Elad SalomonsPosted on Posted in EPANET related, Free software — 11 Comments ↓

A colleague wanted to convert an EPANet file to an AutoCAD drawing. After having a few issues with the DXF2EPAutility he found anothe program for this task – EPACAD.

EPACAD, by the ITAresearch group over at the Universidad Politecnica de Valencia, is a free software which can converts an AUTOCAD file into an EPANET one. EPACAD is able to automatically import the main properties of elements.

EPACAD features include:

  • EPACAD can upload a .dxf exported from AUTOCAD. You will only have to select the layer (or layers) containing the pipes of your hydraulic model to start building your network. As other programs, you needn’t change your AUTOCAD file.
  •  EPACAD is able to read X, Y coordinates of AUTOCAD files and also elevation of nodes (which are the ones describing your pipeline). So, you will get real lengths of your pipes and a reference of the current location of your items.
  • No matter how you draw your pipes in AUTOCAD, EPACAD reads both lines and polylines. Moreover, You can also create two nodes per line (regarding to initial and final node of the pipe) or, considering all the intermediate vertices of the latter in order to edit them later using EPANET.
  • One of the most common problems deals with the connection between pipes issues (due to the inaccuracy in the AUTOCAD files). So, we have developed a useful tool that enables you to automatically solve the connectivity between elements, just setting the allowed distance between independent elements.
  • Before exporting your results to EPANET, you will find a preview of the scenario. There will be some visualization tools to help you to identify small details. This tool will save your time as you can validate your results before final creation of your network.

EPACAD web site and user guide.

Tagged with: , , , ,

by Elad SalomonsPosted on Posted in Water security — 1 Comment ↓

optiEDS – online, real time, event detection system for water networks.

Coming soon…

Tagged with: , , ,

by Elad SalomonsPosted on Posted in Commercial software, EPANET related, Water simulation Packages — 2 Comments ↓

When working with hydraulic models, especially of large networks, the user often face a problem when he wants to compare two versions on the model to see what changes were made. The GeoAdvice Model Comparator by GEOAdviceֲ aims to assist in this task.The program is an Excel Addon (requires Excel 2007) and currently can compare models from the following software:

  • InfoWater
  • InfoSewer
  • H2OMap Water
  • H2OMap Sewer
  • EPANet
  • WaterCad

ֲ 

I have received an evaluation copy of the program and tested it on a small, 126 nodes, network we used for the BWSN. I have madeֲ acopy of theֲ original model and made a few changes to it: removed a few junctions and pipes andֲ added new ones, changed some water quality and time parameters, changed some tank date numbers andֲ changed a control rule setting.

The installationֲ process was very simple and without and issues,ֲ like opening an Excel file. The first stage is to select the modelling software:

Select modelling software

ֲ Then you are prompt to select the two models you want to compare (click images to enlarge):ֲ ֲ 

Select models to compare

ֲ At this point you may select what data you want to compare. I just selected everything:ֲ ֲ 

Select data to compare

Once you press the ‘Compare’ button you get two new sheets in the Excel workbook. One with a summary of the run and the other with a list of model differences:

List of model differences

ֲ At first the program didn’t find all the differences I made to the model but after a few days the GEOAdvice team sent me an updated version that did (there is still a small issue with time parameters which I guess would be fixed in no time).

My overall impression is that the GeoAdvice Model Comparator is a simple to use tool which might come handy to many people who work with different versions of a model. Just think of a case of a team working together on a model and everyone is making changes. It could be very difficult to keep a record of all changes.

The program is not free.ֲ The EPANet version costs range from 495 $CAN for 1,000 pipes to 1,495 $CAN for an unlimited pipesֲ version. For the commercial programs like InfoWater, H2OMap and WaterCAD the prices range fromֲ 995 $CAN for 1,000 pipes toֲ 2,995 $CAN for an unlimited pipesֲ version. The higher price of these versions is because their data structure is more complex and there are more data sets to compare (like scenarios).

A free, open source,ֲ alternative for comparing EPANet INP files could be a program like WinMergeֲ which can compare both folders and files, presenting differences in a visual text format that is easy to understand. Using WinMerge on the two networks I compared was easy and quick.ֲ ֲ 

Using WinMerge to compare INP files

Tagged with: , , , , , , ,

by Elad SalomonsPosted on Posted in Papers and Research, Water security — 1 Comment ↓

ֲ From maplecroft:

A new report evaluating the water security of 165 countries has rated the supply of clean, fresh water to the societies and businesses of 10 nations at “extreme risk.”

I don’t have access to the full report so I have not read it yet. If you have a copy and can shareֲ it with me it would be great 🙂

According to the Water Security Risk Index, released by Maplecroft, a firm specialising in corporate risk intelligence, Somalia (1), Mauritania (2), Sudan (3), Niger (4), Iraq (5), Uzbekistan (6), Pakistan (7), Egypt (8), Turkmenistan (9) and Syria (10) are the countries with the least secure supplies of water.

Water Security Risk Index 2010

Water Security Risk Index 2010

The index is one of over 100 created by Maplecroft to identify risks across supply chains, operations and investments of multinational companies and has been developed by measuring the four key areas surrounding the issue. These include: access to improved drinking water and sanitation; the availability of renewable water and the reliance on external supplies; the relationship between available water and supply demands; and the water dependency of each country’s economy.

The report states that countries in the extreme risk category, including the emerging economies of Pakistan, Egypt and Uzbekistan, are already experiencing internal and cross-border tensions due to limited water resources. Furthermore, as the global climate changes, water stress is predicted to become more acute in these regions and has the potential to threaten stability.

“The fact that Pakistan and Egypt are amongst the most vulnerable nations should send a signal to investors who will need to develop water conservation and security strategies and be mindful of their water use impacts on local communities,” said CEO of Maplecroft, Alyson Warhurst. “These countries also have some of the highest population growth rates in the world, especially around cities, so there is an urgent imperative for renewed policy action underlined by these results.”

Pakistan’s long-running dispute over Kashmir with India (13 and high risk) is in part fuelled by competition for critical water resources that are needed to maintain the growth of industry and investment for both countries. Egypt, which is dependent on water from the Blue Nile, is currently threatening legal action over the construction of the Gibe III dam in Ethiopia, which will further jeopardise its limited supplies; and in Uzbekistan, where an estimated 87% of the population has access to good quality drinking water, tensions are rising with Kyrgyzstan and Tajikistan due to hydro-electric projects on the rivers that flow into the country.

“Climate change and increasing demands from population growth will cause a worsening of water stress over the coming decades,” said Dr Anna Moss, environmental analyst at Maplecroft. “Conflict is likely to spread and intensify as a result of a lack of water security and for the countries that are heavily reliant upon external water supplies the issue of water may become critical. It is essential for business to monitor the risks in their supply chains and operations where they might face current and future exposures.”

Regions particularly vulnerable to a lack of water security include the Middle East and the CIS countries of the former Soviet Union, where all appear in the high and extreme risk categories, except Georgia, Belarus and Russia, which is considered low risk. Africa is also acutely affected by the issue, with 15 countries in the high and extreme risk categories.

The countries with the most stable supplies of clean water include Iceland (165), Norway (164) and New Zealand (163). Other low risk countries include the UK (144) and Brazil (148).

Tagged with:

by Elad SalomonsPosted on Posted in EPANET related, Water simulation Packages — 39 Comments ↓

WaterIng is a software research program of the Multidisciplinary Group of Fluid Modelling in Valencia (GMMF):ֲ

WaterIng is a software package for water distribution system design and analysis. It offers a multi-objective evolutionary optimization engine based on distributed artificial intelligence to support design and operation decision-making (Agent Swarm Optimization). Improved solutions from both hydraulic and economic points of view can be implemented, profiting from the high flexibility of WaterIng platform for defining and evaluating objectives. Different rule-based agents can be incorporated to perform search of solutions more efficiently; depending on the characteristics of the problem, agent population size may vary automatically. WaterIng makes it possible to manage water network data easily by using TableView; additionally, a useful visualization of networks elements over a GIS-based MapViewis done. It is possible to import shapefiles, information contained in EPANET files (.INP), or simply copy and paste information from Excel tables to Tableview. Design solutions or existent systems can by analyzed in steady state flow including extended period simulation.ֲ

Water Distribution System Design and Analysisֲ

I have downloaded the program and installed it (you will need the Microsoft .NET framework 3.5 and some VC++ 2008 redistributable files). Unfortunately I was not able to run the program and I kept getting an error messages while trying to start a new project. Searching the WaterIng website I found a few screenshots of the Hanoi water network whichֲ is a well known benchmarkֲ optimization problem.ֲ

WaterIng – Hanoi Water Distribution Network

The WaterIng team used it to demonstrate the program optimization capabilities. It is not explicitly written but from the following image, showing a pareto front,ֲ I understand that the two optimization objectives were: minimum cost (horizontal axes) and minimumֲ head deviation.ֲ

Hanoi water network optimization – pareto front

One can see that on the very right hand side the cost values are around 6,100,000 with little or no head deviations. This value is in the range of previous published results.

Update: a limited version of WaterIng is available over at http://www.ingeniousware.com.

Tagged with: , , , , ,

by Elad SalomonsPosted on Posted in Events & news, Papers and Research — 1 Comment ↓

During the summer of 2009 a large number of water pipe breaks occurred in Los Angeles. Apparently,ֲ  there were 101 blowouts in the summer of 2009 (July, August and September) compared to 42 in 2008, 49 in 2007 and 48 in 2006. As a consequence of the public request for an explanation an independent investigation was requested to study the cause of these blowouts. Last week the experts review was published and the findings are fascinating:

The Investigation Teamג€™s findings reveal a connection between the Cityג€™s water-rationing program and the increase in pipe breaks during the summer of 2009, especially with cast iron pipes. At various locations in the LADWP water distribution system, the water pressure dropped significantly on Mondays and Thursdays after the beginning of the water rationing program on June 1, 2009. Those water pressure drops on these days were caused by an increased water flow during the watering of lawns. As a result, the cyclic levels of water pressure increased and accelerated the metal fatigue failures of aged and corroded cast iron pipes.
These findings conclude that that the sudden changes of water pressure in the system, attributable to the water-rationing program, had a negative impact on cast iron pipes with lower fatigue resistance (i.e. especially corroded cast iron pipes).

The cyclic pressure drops on Mondays and Thursdays is shown from the recorded data:

In the conclusions the experts team write:

There is evidence that the cyclic amplitudes of internal water pressure increased due to water rationing and contributed to the failure of cast iron pipes by metal fatigue. At various locations in the LADWP water distribution system, the water pressure dropped significantly on Mondays and Thursdays after June 1, 2009, when the water-rationing program began in Los Angeles. Temporary drops in water pressure on these days were caused by increased water flow during the watering of lawns. The expert review team study has shown that increased amplitudes of cyclic daily pressure can have a negative impact on pipe materials with lower fatigue resistance, especially corroded cast iron pipes. Fatigue effects on cast iron pipes do not appear immediately, but accumulate gradually. Cycling at increased amplitudes of pressure accumulated gradually in June through September, 2009 as aging cast iron pipes with low fatigue resistance were subjected
to elevated pressure cycles. Fatigue-related pipeline breaks resulted in pipe failures (referred to as blowouts), which raised concerns from the media and the public because of the damage they caused to street pavements and properties.

Additional resources (opens in new windows):

Tagged with: , ,

by Elad SalomonsPosted on Posted in EPANET related, Free software, Water simulation Packages — 3 Comments ↓

Tim Hirrel sent me his new product release info for Tdhnet:

3 new hydraulic network modeling products have been released and are now available for download. These products are the latest releases in the Tdhnet line of hydraulic network software and represent a major breakthrough in the availability of cross platform hydraulic network models. TdhLite, available as executable files for both the MS Windows and Linux operating systems, provides the essential functions of network modeling with an extremely light footprint. These programs require no external commercial software and can handle networks of significant size even on the highly portable netbooks frequently used today. Please see the related articles, ג€œTdhLite Overviewג€ and ג€œWhy TdhLite Is a Better Choice Than Epanetג€. TdhnetAPI is a breakthrough product providing a highly advanced application program interface for any software needing hydraulic network functionality. Please see the related article ג€œTdhnetAPI Overviewג€. All of these products are now available for downloading from Tdhnet.com.

I always like to see new software in my field but what caught my I is the post titled “Why TdhLite Is a Better Choice Than Epanet“. A nice feature is the ability toֲ  pause and examine results at a specified time or interval and also to change data at any specified time during a solution sequence. The user can modify many input parameter, including:

  • Demand at an individual node and demand factors for all nodes or a group of nodes.
  • The status of any pipe, pump or valve.
  • The status of a set of Rules so that different sets of Rules can be in effect during different times of the day.
  • Any number of Change Sets can be included with a network so the user can easily return to a previous project or objective.

I have download the program and installed it on MS Windows 7 without any issues. I have done only a little of playing around and did not find the program to be very intuitive It is takes a long time to get going and enter just a small network. I imported an INP file from EPANet (Net2) and was able to make a successful run and also pause the simulation at each time interval. I think that Tdhnet needs to mature in its user interface and make the network drawing more intuitive.

ֲ Update 28/04/2010: Tim just sent me a message with a few pointers:

A couple of features of the map interface may not be immediately obvious, but useful nonetheless. Zooming can be accomplished by rolling the mouse wheel and panning can be accomplished by double clicking the mouse. I have found these features to be a convenient method of navigating a map. Also, by right clicking from pretty much
anywhere, the user can go to any related feature of the model, including elements on the map. Updated versions have already been made available on the website and updates will likely continue with some frequency as feedback is received. Also now available is a document intended to help users experienced with Epanet quickly understand the differences with Tdhnet. This document, UsingEpanetData.pdf, and the user’s manuals can be downloaded by following the Tdhnet_Library linkon the Tdhnet.com website.

Update 08/06/2010: a few readers from mainland China reported that the Tdhnet web site is unavailable. I think the reason is that the site is hosted on the Blogger platform by Google. Some Google services are blocked from within mainland China as reported on Google’s Mainland China service availability page.

Tagged with:

by Elad SalomonsPosted on Posted in General — 2 Comments ↓

Online water demand data, published by EPCOR, show that Canadians have invented a new kind of sport – synchronized toilet flushing. It seems that all the TV viewer of the Olympic gold medal hockey game flushed their toilet at the same time during breaks in the game.

ֲ 

ֲ 

Caption: Synchronized toilet flushing

via: Pat’s Papers

Tagged with: ,