Computer Aided Design

Anonymous Blocks in AutoCAD

Written By Allan using AutoCAD 2004

"AutoCAD uses anonymous blocks for supporting hatch patterns and dimensions. These types of blocks are also created using AutoLISP or similar means, but cannot be intentionally created in the drawing editor. Also, anonymous blocks cannot be modified using AutoCAD editing commands." - www.autodesk.com.au

*U### = anonymous blocks

*E### = anonymous non-uniformly scaled blocks

*X### = anonymous hatches

*D### = anonymous dimensions

*A### = anonymous groups

Code restructuring: The common type of reengineering is code restructuring. Some legacy systems have a relatively solid program architecture, but individual modules were coded in a way that makes them difficult to understand, test, and maintain, In such cases, the code within the

suspect modules can be restructured. To accomplish this activity, the source code is analyzed using are structuring tool, Violations of structured programming constructs are noted and code is then restructured. The resultant restructured code is reviewed. and tested to ensure that no anomalies have been introduced, internal code documentation is updated.

Forward Engineering: In an ideal word, applications should be rebuilt using a automated 'reengineering engine'. The old program would be fed into the engine, analyzed, restructured, and then regenerated in a form that

exhibited the best aspects of software quality. In the short term, it is unlikely that such an 'engine' will appear, but CASE vendors have introduced told shat provide a limited subset of these capabilities that addresses specific

application domain. More important these reengineering tools are becoming increasingly more sophisticated.

Forward engineering, also called renovation or reclamation, not only recovers design information from existing software, but uses this information to alter or reconstitute the existing system in an effort to improve its overall quality. In most cases, reengineered software reimplements the function of the existing system and also adds new functions and/or improves overall performance.

The short easy answer is that with solid modeling, forms are built-up by drawing outlines and protruding them into forms, as well as using other protruded outlines to cut forms. Often these shapes are more geometric overall, and solid modeling is usually used to create the internal details of products. SolidWorks is a solid modeler (but can create surface forms too)

Surface modeling develops shapes by stretching a "surface" between 3d curves that you individually create. With it you build forms by creating one small surface at a time, slowly creating the complete shape. The intersections between the surfaces are very controlled so they can be very very smooth or crisp like a crease. Usually the shapes are more freeform and sleeker than an object that was created with solid modeling, but some people are very good and the lines blurrr.. Alias is a surface modeler, but Solidworks can create shapes with surfaces too

olids modeler: Starts with a solid object. You add and subtract other solid objects to it. If you cut into it, you're left with your solid object minus what was cut out--just like in the real-world. It's all very rational.

Many solids modelers are "parametric" meaning you can go back and look at the list of commands you've executed since the start of your model (the "construction tree") and change anything (hoping your model doesn't "break.") Very useful!

Pro/E and Solidworks are the most popular.

Surface modeler: A bunch of infinitely-thin membranes defined by boundary curves. If you want, you can connect one membrane to another, creating a "water-tight" form that looks solid, but if you cut into it, it would be hollow and you'd have to patch the missing cutout piece (intersect tools are typically used to automate this.)

Surface modelers generally aren't parametric. There is no construction tree. It's very hard to change something you did and expect the rest of your model to update.

Why would you use a surface modeler then? Because it's more freeform, and historically, the tools have allowed you more control over the shapes of those "membranes" than if you were using a solids modeler. And because designers have been attracted to this, the user-interfaces tend to emphasize the freeform more than the solids-modelers, which cater to engineers.

Alias and Rhino are the most popular.

there are some other differences like parametric history and assemblies as well that make Solidworks a worthwhile software to complement your Alias skills...

1. Soil Liquefaction

2. Ready mix concrete plants

3. Pile foundation

4. Improvement of bearing capacity of sandy soil by grouting

5. Ground improvement technique

6. Use of plastic as soil stabilizer

7. Erosion control in slope