Temperature Sensors - Thermocouple

As the other groups mentioned, resistive temperature detectors (RTD), simple mercury thermometers, and more technologically advanced infrared sensors are all used to sense temperature. I would like to discuss a different type of temperature measurement – thermocouples. As Elda mentioned, thermocouples tend to be less accurate than RTDs, but they are still widely used in industry. They are simple and easy to understand. They have some advantages too which include a wide temperature range, robustness, rapid responsiveness, and lack of self heating.

Like most scientific inventions, the thermocouple was invented by accident. An Estonian physician accidentally discovered the ability to sense temperature by the effect of joining two different metals together. When two different metal wires are joined together and a temperature difference exists along them, they generate voltage, which is indicative of the temperature difference. Figure 1 presents a simple thermocouple diagram: the junction where the metals meet is called the measurement junction, or the hot junction. That point should be exposed to the temperature we would like to measure. The wires should then be placed in what’s referred to as the reference junction, or the cold junction. At that point the wires are generally inserted in a bath of ice water to maintain a constant 0 degrees Celsius. Thermocouples measure the relative temperature between the two junctions, and therefore the reference junction must be known, and is usually kept at 0 degree Celsius.

Figure 1: Thermocouple Diagram

The metals used are indicative of the sensitivity, temperature range, and voltage range measured by the thermocouple. Table 1 has this information about the common types of thermocouple. The types also indicate the error in measurements. As mentioned before, the error in measurement can be significant when using thermocouples. Figure 2 shows the possible error for four different thermocouples for the temperature range of 0 to 400 degree Celsius.

Table 1: Types of Thermocouples

Figure 2: Error in Thermocouple Measurements

What is actually measured when using a thermocouple is the voltage created by the difference in temperature. In order to interpret this date, one needs to know how to convert the voltage data to meaningful temperature data, which is, again, dependent on the type of thermocouple. The seedback coefficient is the voltage change per degree Celsius in μV per degree Celsius, and it is represented in Table 2 for the different thermocouple types at 25 degree Celsius. The seedback coefficient is not constant, though, which makes the fitted graphs used to interpret the temperature nonlinear. Software needs to collect the voltage data and have a function imbedded within it used to convert these measurements to useful temperature data.

Table 2: Seedback Coefficient at 25 Degree Celsius

References:

http://cds.linear.com/docs/Application%20Note/an28f.pdf

http://www.analog.com/library/analogDialogue/archives/44-10/thermocouple.pdf

Pressure Sensors

According to the National Instruments website, “because of the great variety of conditions, ranges, and materials for which pressure must be measured, there are many different types of pressure sensor designs” [1].

My fellow classmate, G. Carpenter, first addresses in her post the most common type of pressure sensor (strain gage, see Figure 1 for cross section) and what it measures and how it is translated to indicate pressure.  She then discusses different categories of pressure gauges (force collector and other) and their electrical outputs (millivolt, amplified voltage, and 4-20 mA).

Figure 1: Strain Gauge Pressure Sensor Cross Section [1]

I will now discuss the other two most universal types of force collector pressure transducers (according to National Instruments): variable capacitance and piezoelectric.

A variable capacitance pressure sensor measures “the change in capacitance between a metal diaphragm and a fixed metal plate” and the capacitance changes when the distance between the two plates changes and the degree of this change is converted into an electrical signal [1] (see Figure 2).  (Capacitance is described as the “the ability of a body to store electrical charge” [2].)  These types of sensors are also described as, “very stable and linear, but sensitive to high temperatures and more complicated to setup then most pressure sensors” [1].

Figure 2: Capacitance Pressure Sensor Diagram [1]

A piezoelectric pressure transducer utilizes the electrical properties of naturally occurring crystals such as quartz [1], and uses these stacks of crystal to convert motion into an electrical output as they become strained [3] (see Figure 3).  They require no external excitation and are "rugged" [1], however, are not effective with dc or steady-state conditions [3].  These sensors are also highly susceptible to shock and vibration [1], and also require special signal amplification as their output signal levels are low [3].

Figure 3: Piezoelectric Pressure Sensor Diagram [1]

Sources:

[1] http://www.ni.com/white-paper/3639/en

[2] http://en.wikipedia.org/wiki/Capacitance

[3] http://www.digikey.com/us/en/techzone/sensors/resources/articles/what-you-need-to-know-about-pressure-sensors.html

OODB

Object-oriented databases are an important evolution for database management systems because can handle data that needs to be managed for a large variety of applications. Object-oriented databases, commonly referred to as OODB, have been developed to meet the need for a database that is more flexible and can handle the need for custom operations. 

One of the most useful aspects of this type of database is that it is not limited by the types of data and language typical of traditional databases. It provides flexibility in that both an object and all of its possible functions and methods can be specified. Because of this flexibility, different data types can be used within this type of database to serve the needs of the industries such as design systems like CAD, scientific, medical, and multimedia databases, and geographic information systems. These data types allow the development of programs that consist of independent objects as opposed to basic information. Independent objects can contain functions and methods that specify what that object can do.

A lot of the research I did for this post was difficult to understand because I have no experience with computer programming and my knowledge of that field and common language used is slim to none. One thing I was able to understand was how relevant object-oriented databases are to our field of architectural engineering design, especially in terms of developing models using BIM. Revit is based on an object-oriented database. Each object you use or place into a model is part of a class and has its own parameters and functions. The objects also communicate with other objects within the model. Without object-oriented databases, we would not have the BIM software available to us today.

Because this type of database is very specialized, it is not relevant for all fields and is not as commonly used as the traditional database; however, the opportunities available for industries looking for a more flexible and customizable database management system find OODBs to work exceptionally well. Due to the increased use of object-oriented databases, standards and specifications have been developed for using this type of programming.

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Nathan gives a pretty good overview of the function of SQL servers, and the degree of standardization that is common to the language. As he mentions, it is important to have a Structured Query Language to manage databases in an understandable way, allowing us to find and modify data once the database has been created. After some initial confusion pertaining to the jargon used to describe how SQL works, I found the actual functions it implements to be very intuitive. Each function's name describes what it does. For example, the all-important SELECT function allows programs to search and retrieve data from a specific database table, with further modifiers embedded within the function to refine the search (FROM, WHERE, etc.), and organize the output (ORDER BY, GROUP BY). I found Wikipedia's explanation of this function (and others) very helpful.

Figure 1 - SELECT function explanation

I like that David describes the databases themselves as "glorified excel sheets," especially since this definition is coming from someone with some experience with databases. From my rudimentary understanding of the topic, that is exactly how I pictured and SQL database, some enormous table made up of labeled columns with rows of data beneath. It makes sense that by this system, and particular piece of data can be pinpointed by some row and column designation, much like an X and Y coordinate in the cartesian system.

What intrigued me most about this week's topic was not necessarily how the system works, but how often it needs to work. I gather from the articles I read, that every single user-interfaced program uses some form of database and query system to make it run. For simplified applications this may be a flat-file-database, as David explains. However it is my impression that, for the large majority of complex applications, the SQL format is used. A recent article puts into perspective the importance of the ability to manipulate and query these formatted data.  As our sensing capability and aptitude for data recording grows, the challenges involved in organizing, maintaining, and using this data also grows. For example in the medical field there are virtual reams of unused data pertaining to patient records, and no unified system for managing all of this. As data becomes more and more digitized, it seems reasonable that we must decide how we want to organize this data so that it is easily accessible when we need it. The SQL is currently the ANSI specified way to do that, and while it is not without complications, the basic structure of database and query language remains the same across the board.

Finally, one of the biggest issues in current SQL design is the timing of the SQL servers. Database size has grown significantly since the SQL language was invented, and as a result we are having to deal with time lag as SQL applications search through these seas of information for specific data. ANSI is still updating specifications, with its latest release in 2012, to account for the evolving nature of database organization and navigation.

References:

"Database Management: Big Data will soon be the norm" - Sunday Business Post

SQL For Dummies - 7th Edition

Object Oriented Databases

An object oriented database is one that attempts to model the real world. The database defines objects by using different classes that can perform actions or have actions performed on them. As Kayleigh stated, Revit is an object oriented database because it models real objects inside buildings. An object has a class and different attributes that define it as well as methods that can be applied to it. An example of class and attributes in Revit could be Air Handling units or Windows, etc. Each class has different attributes defined when the families are made, such as door size, material, manufacturer, etc. The example in the article I read by Ramon A. Mata-Toledo and Pranshu Gupta uses automobiles as an example. The Class is automobiles and the attributes are the color, make and model and other attributes that can define an individual car. The methods are things that cars can do or have done to them such as park or be washed.

The applications of object oriented databases to intelligent building are numerous. For instance, as already discussed, Revit already uses an object oriented database to model architectural, structural and MEP designs; but the applications do not end here. Object oriented databases can call on a model to simulate building performance. An air handling unit class can have further modeling done such as fan power, cooling and heating coil information and other information in order to perform simulations with different building zones to model energy performance. Other building systems can also be simulated as well as full system integration simulations that show how different building systems work together. 

Sources:

http://www.accessscience.com/content.aspx?searchStr=object+oriented+programming&id=757337

http://beesl.syr.edu/pdf/Poster_VirtualBuilding_KF.pdf

Object-Oriented Databases

Week 6

2/12/13

Databases – Object Oriented Databases

                An object oriented database is a particular type of database that is most commonly used when CAD software is being utilized.  When the database is used alongside some kind of computer program that functions on object-oriented programming (C++, Java), it becomes a object-oriented database management system (OODBMS).  This acronym is common because a object oriented database is only relevant when being utilized in this way.

                The easiest way to explain the difference between an OODBMS and a traditional relational database is that the “data” is stored as objects rather than large columned lists.  These objects are created when multiples data sets have defined relationships and characteristics.  In this sense, data can be given specific attributes that allow these defined relationships between the data to be taken advantage of.  In this sense, an object is something that will contain strings of data input along with a functioning code that manipulates and presents this data in a meaningful way.  As Kayleigh points out, large MEP manufactures like TRANE and Touzer can use OODBMS to provide accurate representations of their systems from large sets of data and create realistic “models” of their products.

                This characteristic allows for data to be much more useful and relevant because it can be manipulated and altered in order to analyze various design options.  The data is no longer “2-D” and can be used easily as a visual object in some kind of GUI program.  Instead of looking at a list of thousands of temperature differences resulting from window angles in a building and trying to deduce a reasonable design, someone can take an object in a OODBMS that represents a window and apply multitudes of different designs and implementations to that window.  Data is being simultaneously called up from multiple points and put through en executable code that reflects that change in the design.  A real world example of this is provided by Jeanine in her post.  She explains how people like aircraft carriers can use OODBMS to manage, organize and enhance the thousands of small parts used in an airplane.  Instead of gathering tensile stress on a component and throwing it in a list, someone can use OODMBS to understand the effects of the data, designs something better and implement in the real world.

                I want to close this by saying that I am no extremely computer savvy and am especially challenged by the world of programming.  The information above is what I was able to take out of what I read while trying to make sense of a lot of programming language.  I am open to comments and corrections from someone less confused by the subject matter.  

SOURCES:

http://en.wikipedia.org/wiki/Object_database

http://www.comptechdoc.org/independent/database/basicdb/dataobject.html

Week 6: Uses of Databases in Construction Firms

Databases are very useful in keeping an organized record of information and there is a vast range of types of information that can be stored in these databases. Construction firms many times look to keep record of their construction equipment, designs, construction members within designs, previous projects, clients’ contact information, materials and/or their costs and manufacturers, elevations of a construction site, rainfall data of a subject area, and lots of other valuable information they may look to store away for later use. A lot of times a database is put together for information that is no longer of urgent use but that may be of value to access at a later date in time.

In addition to simply accessing the raw data that is stored into a database, certain programs are able to use these databases to analyze the data and output referenced analyses. Programs such as ArcGIS are able to use databases in order to spatially analyze the data and create maps that show the stored information in ways that can be useful for the needs of the user. For instance, a construction firm could use a database that has the addresses or coordinate locations of material manufacturing plants to find the closest plant to their construction site and even find the quickest, shortest route from the plant to the site. Another example could be analyzing a database that has the cost information for specific types of a common construction material over time. With a database of this information, one could find the trend or growth rate of the cost for these materials and come up with an estimate for the price of the material in the future when a project will actually enter the construction phase.

I found it interesting in Issa’s post (http://ae-510-ay12-13.blogspot.com/2013/02/databases-in-construction-firms.html) to see that databases have been in use since the 1970’s and I too have seen first-hand at some of my co-op’s the transition from paper to electronic copies of files. The progress that has been made over the years is vast and much room is left for advancement in the use of these databases and how we can implement them to our advantage in construction.


Source:
http://pmbook.ce.cmu.edu/14_Organization_and_Use_of_Project_Information.html

Object Oriented Databases

As engineers in this modern era, databases are used in almost every aspect of our careers.  While working on co-op I learned to use databases that the firm created, that were provided by equipment manufacturing, and that had been used for BIM or Revit purposes.  The database most relevant to this course would have to be the one we used for Revit and AutoCAD.  As a structural engineer, most of the materials we work with are somewhat generic and do not have specific manufacturers providing models of their product.  For the most part, Revit has the steel shapes stored within the preloaded database. However, when it came to concrete design, we often had to create our own families within the database for different types o concrete beams and columns.  Eventually this database begins to cover almost every type of beam or column and therefore lessens the requirement for engineers to make new families for a given project. After reading Maria's and Kayleigh's post I was able to understand a little better what exactly databases are and what they are used for within the BIM category.  While I had an idea of what an object oriented database is, I wasn't actually clear until reading their posts. 

Object oriented databases are exactly what their name implies, they store objects rather than data points.  This is obviously geared towards design applications, whether they be in CAD, BIM, manufacturing, animation, or anything of the sort.  This allows for the designers to be more efficient with their design and modeling.  I know that if I had to redraw everything in Revit or even AutoCAD, my job would have taken twice as long, which would dramatically decrease my efficiency.  I only see the use of these databases increasing tremendously over the course of our careers.  With the theme of this course being intelligent buildings, I feel this topic fits perfectly.  As engineers and designers, we will definitely continue to utilize these databases to further the efficiency of our process and design more intelligent buildings. 

http://en.wikipedia.org/wiki/Object_database

ieor.berkeley.edu/~goldberg/courses/F04/215/215-OODB.ppt

http://www.25hoursaday.com/WhyArentYouUsingAnOODBMS.html

Databases in Design Offices

In the USA, design firms offering geotechnical services are typically given the responsibility to perform an investigation and afterward produce a report based on the findings. This single company approach is different from the way the same services are performed in the UK. The technical information gathered by firms in the USA can be contained in databases developed by each company, as the report is the only documentation that must be understood by more than one party. In the UK, the geotechnical services are often performed by multiple companies, signifying the need for a universal input format to allow information be interpreted by multiple players. This need was met with the implementation of the “AGS” format, which offers the highest level of acceptance into other programs and databases. The information can be accessed in text editors and then imported into each companies chosen form in order to produce bore logs, graphs, table and cross section figures. Design firms are known to use the information from soil borings early in the process to establish the extent and schedule of the tests that must be performed by themselves or an investigative contractor.

In the office, architects and engineers use databases that contain discrete information of objects in the BIM process. Software systems such as Bently’s Microstation and Autodesk’s Revit allow the user to create tags and assign them to elements different elements in the modeling environment. This feature allows the designers to export the information to useful platforms such as Excel or a database program to sort and record in relation to other parameters. Designers at manufacturing companies are using databases to store information of each of the products that they carry. Portions of these databases are then shared with designers to allow the smooth exchange of specifications and other project specific details. An example of this is in Brian's post, where he described creating families using objects to organize information of each component in the building. These objects contain information that is taken, sometimes from other sources and linked to the BIM. This allows designers to pull information about the object to include in schedules, charts and other analysis procedures.

I have experiences with databases as a user and developer were those that included cost information of each construction trade for completed projects. Project information was accessed using a search query that included the type of building, number of levels, construction materials and function. Once the reference building was selected, the user could duplicate the project and then change various parameters, such as the current year, location and indexes of material costs. Jalpesh's post mentions that design firms can archive the information used for a design so that the firm can access the information for future projects. This archiving process is valuable because designers can re-use portions of the design that they know already work. This has been happening in design long before databases but was known as "rules of thumb". Similar to design, after the project is selected it could then be modified by omitting certain trades based off of the building the user was attempting to model. The database contained information for adjustments due to location and time and would output a project file that included costs for each trade involved. The information was utilized in a design-build project team to deliver accurate costs at the conceptual level of design. I believe that at a point in the future, with the progression towards integrated design with multidisciplinary teams, specialty contractors will begin to share more database information with the designers in order to expedite project completion and minimize errors.

Companies can utilize databases for estimating material and labor costs for structural steel. The database of each type and size of steel members were linked to respective information such as weight, area, required bolts, crane lifts and various other metrics for the piece. Information could then be derived from the job summary such as labor hours for painting and assembly, crew productivity rates as well as weight for the galvanization process.

1.      Chadwick, Neil C. "Data Transfer and the Practical Application of Geotechnical Databases." Data Interchange for Geotechnical and Geoenvironmental Specialists, n.d. Web. 10 Feb. 2013.

Uses of Databases in Design Offices

Databases in the design office environment are like professionally trained personal assistants who can respond to various types of commends with a click of a button. Designers mainly benefit from archive databases which can provide multiple disciplines of information immediately while working on a project. Design companies are starting to build their own databases which archive all the designs they have produced before and all the research which went behind the completion of all those designs. For example University of Salford, UK and John McCall Architects (JMA) are collaborating on producing a database which will assist with a process known as Knowledge Management which can provide aid to designers at JMA to work more efficiently on their projects.

The database for the Knowledge Management strategy will act as an employee of the firm which knows every detail of work that the firm performed to date which will always stay with the firm never to be lost due to retirement, termination, or so on. Additionally this virtual employee’s knowledge will be accessible for all employees all the time through the database setup with “features including the incorporation of video and audio clips, links to external authoritative sources, content qualifiers in the form of source or reference metadata, and annotation capabilities to capture tacit knowledge” (Egbu and Sidawai). So let’s say an structural engineer is designing a special joint which he or she is not fully sure of how to encounter the design of that joint, the designer can search their companies’ database and see if that type of joint with similar constraints was design before in any of their projects. If so the designer does not have to start from scratch because the database will provide the history and facts about that design such as the efficiency, positivity, problematic factors, constraints to be caution with and so on.      

          

The database being used for Knowledge Management process at JMA is one of many different types of databases which are part of the design industry today. As Maria Gonzalez mentioned in her blog post of how databases are part of the BIM design process which provide the functionality of keeping information of all the different components of the building which results in the facilitation of documentation, cost estimations, and etc. which allows designers to work more efficiently saving cost and time. Both the database Maria and I mentioned provide better efficiency leading to common benefits of saving time and cost, some key results of successful databases.   

Sources:

(Egbu and Sidawai) http://www.itcon.org/data/works/att/2012_5.content.03794.pdf

Databases in Construction Firms

“Databases allow you to manage your data more efficiently, avoid errors and manipulate it easily.” 

Construction firms are acknowledging the fact that staff and subcontractors come and go and the retrieval of data and information about projects becomes difficult.  With this in mind, construction firms find ease with databases.  There always comes a time when you either have a staff member replaced or simply after the project is completed, years later there is a need to recover the documents from a past project.  This is where databases come into play.  By saving and storing past, current, and potential projects, contractors, suppliers and clients, the workplace becomes organized as well as time and cost efficient.  With a database, everything is stored in one place where authorized staff has access to find the most up-to-date information. In order to obtain such information, the System Query Language (SQL) plays a role as the data language that helps organize and retrieve stored information from the database.  As Elda mentioned in her blog, having a standardized language is very important as it “allows everyone to access and manipulate databases.” 

After my last coop in a construction claims company, I soon came to realize the necessity of databases in the industry.  Considering that the company hired interns for a period of six months, they needed to have a certain file storage unit where future employees could easily attain information.  Because this company had international offices and worked globally, operating with a database was very useful and practical.  In Ryan’s post he said that for large construction firms that operate in multiple states or countries, databases come in handy “to ensure they are in compliance with disposal standards of the local area that the project is in.”  I agree with this statement because this would be a great communication source in order for companies to comply with standards.

Since the 1970s, databases have progressively been integrated in all industries and now we can see a greater implementation in construction firms.  Now, companies are found in a transition stage where the mountains of file boxes are being converted into database files, improving document and information retrieval in an efficient manner.

Sources:

"Benefits of a Relational Database." Sunadal Data Solutions. SDS, 2013. Web. 12 Feb. 2013. <https://www.sunadal.co.uk/db.php>.

"Construction and General Contractors Database." Oddity Software - Databases, Development and Design. Oddity Software LLC, 2013. Web. 12 Feb. 2013. <http://www.odditysoftware.com/page-datasales165.htm>.

"Database." Wikipedia. Wikimedia Foundation, 02 Dec. 2012. Web. 12 Feb. 2013. <http://en.wikipedia.org/wiki/Database>.

"Why Use the Planchest Database?" Planchest. N.p., n.d. Web. 12 Feb. 2013. <http://www.planchest.net/Why.aspx>.