The thermal decomposition of nitrates – ‘writing with fire’ 31 A message is written on filter paper with a solution of sodium nitrate and is then dried‚ rendering it invisible. Applying a glowing splint to the start of the message makes the treated paper smoulder and the message is revealed as the glow spreads its way through the treated paper. Lesson organisation The demonstration takes about 10 -15 minutes. It could be a student activity‚ but with a large class it will need a well
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The Iron-Carbon Diagram There are two iron-carbon equilibrium diagrams: - stable iron-graphite Fe-Gr - metastable iron-cementite Fe-Fe3C The stable condition usually takes a very long time to develop. The metastable diagram is of more interest. Fe3C iron carbide called cementite because it is hard. Following phases exist on Fe-Fe3C diagram: - liquid solution of iron and carbon (L) - ferrite ( ) – an interstitial solid solution of carbon in Fe (bcc). At room temperature ferrite is ductile but
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USE-CASE DIAGRAM EXERCISE 1. Draw a use case diagram for an ATM machine with the following functionality. A customer’s interaction with the system involves logging in‚ making withdrawal requests‚ deposit requests‚ and balance inquiry requests. If the customer logs in‚ there is a possibility (although rare) that the system will confiscate the card (for example‚ if the login is incorrect or if the bank determines that the customer’s balance is significantly under zero). Card confiscation involves
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7.7.4 Activity Diagram The progressions of an action chart are operations‚ particularly exercises from the state model. The motivation behind an action chart is to demonstrate the progressions inside an intricate procedure and the sequencing requirements among them. A few exercises run perpetually until an outside occasion interferes with them‚ yet most exercises inevitably finish their work and end themselves [7]. The finishing of a movement is a fruition occasion and normally demonstrates that
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Entity-Relationship Diagrams (ERD) Data models are tools used in analysis to describe the data requirements and assumptions in the system from a top-down perspective. They also set the stage for the design of databases later on in the SDLC. There are three basic elements in ER models: Entities are the "things" about which we seek information. Attributes are the data we collect about the entities. Relationships provide the structure needed to draw information from multiple entities. Generally
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Lab 5 DECOMPOSITION (Nov 2‚ 2011) Introduction: Decomposition is the breakdown of organic material into its smaller molecules and elements. (This term is generally considered as a biotic process but one may find it also used to describe an abiotic process‚ e.g.‚ due to weathering.) The decomposing organisms may use the release of elements for nutrients and by breaking apart the carbon-carbon bonds in organic matter this can release energy for them. These smaller molecules and nutrient elements
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Turtle Diagram Inputs Supplier . Materials/Equipment Measure(s) Process Support Process(es) Outputs Customer Competence/Skills/Training 1 Turtle Diagram Process Steps that make up the process Explanation of how to do the process Could include Procedures and Work Instructions Or parts of Procedures and Work Instructions 2 Turtle Diagram Process Questions Does the process meet the requirements of the standard? Compare what is written to the standard How do you do the process? Have them
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The Hertzsprung-Russell Diagram or‚ the H-R Diagram for short‚ is a graph which plots stars according to their temperature and absolute magnitude. This graph reveals a pattern‚ which in fact is quite interesting. The H-R Diagram is named for the two astronomers‚ Ejnar Hertzsprung and Henry Russell‚ who discovered this pattern of stars. These two astronomers independently discovered that comparing magnitudes and spectral class (color) of stars yielded a lot of information about them. <br><br>One key
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Functions and graphing functions Basics: A function is a rule that changes input into output A relation is any set of ordered pairs A function is defined as a set of ordered pairs in which no two ordered pairs have the same element A function must give exactly one unique output for each input Also called a mapping or simply a map The set of input numbers is called the domain The set of output numbers is called the range The set of all possible outputs is called the co-domain The range is generally
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DFD Yourdon Recently reviewed In the late 1970s data-flow diagrams (DFDs) were introduced and popularized for structured analysis and design (Gane and Sarson 1979). DFDs show the flow of data from external entities into the system‚ showed how the data moved from one process to another‚ as well as its logical storage. Figure 1 presents an example of a DFD using the Gane and Sarson notation. There are only four symbols: Squares representing external entities‚ which are sources or destinations
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