I want to introduct something about Laser Cutting Machine.Specifications: 1) Left-right double control box with convenient operation 2) High flat and stainless steel netty workbench 3) Linear rail to guide with exact gear and rack to transmit 4) Laser system of the radio frequency to choose assembling 5) Double exact rail and rigid beam 6) 32 digits DSP chip core of the controller promoting movement performance fullyFeatures: 1) Adopting the most advanced 32-bit high speed DSP to build the SmartCarver controller, we have largely improved the performance of such series. The S type speed control software helps to provide fast and consistent speed, assisting the auto attenuation compensation to work on different part 2) The machine components use import gear, rack in transmission system, it ensure high precision effect under high-speed movement. The machine tool-roll processing workbench is very steady and reliable, it work in automatic feeding system, it fit to high strength, high 

(Redirected from Top-down)

“Top-down” redirects here. For other uses, see Top-down (disambiguation).

Top-down and bottom-up are strategies of information processing and knowledge ordering, mostly involving software, but also other humanistic and scientific theories (see systemics). In practice, they can be seen as a style of thinking and teaching. In many cases top-down is used as a synonym of analysis or decomposition, and bottom-up of synthesis.

A top-down approach is essentially breaking down a system to gain insight into its compositional sub-systems. In a top-down approach an overview of the system is first formulated, specifying but not detailing any first-level subsystems. Each subsystem is then refined in yet greater detail, sometimes in many additional subsystem levels, until the entire specification is reduced to base elements. A top-down model is often specified with the assistance of “black boxes” that make it easier to manipulate. However, black boxes may fail to elucidate elementary mechanisms or be detailed enough to realistically validate the model.

A bottom-up approach is piecing together systems to give rise to grander systems, thus making the original systems sub-systems of the emergent system. In a bottom-up approach the individual base elements of the system are first specified in great detail. These elements are then linked together to form larger subsystems, which then in turn are linked, sometimes in many levels, until a complete top-level system is formed. This strategy often resembles a “seed” model, whereby the beginnings are small but eventually grow in complexity and completeness. However, “organic strategies” may result in a tangle of elements and subsystems, developed in isolation and subject to local optimization as opposed to meeting a global purpose.

Contents

1 Computer science 

1.1 Software development 

1.2 Programming 

1.2.1 Advantages of top-down programming 

1.2.2 Disadvantages of top-down programming 

1.2.3 Bottom-up approach 

1.3 Parsing 

2 Nanotechnology 

3 Neuroscience and psychology 

4 Management and organization 

4.1 State organization 

5 Architectural 

6 Ecological 

7 Notes 

8 References 

9 External links 

// 

Computer science

Software development

Part of this section is from the Perl Design Patterns Book. 

In the software development process, the top-down and bottom-up approaches play a key role.

Top-down approaches emphasize planning and a complete understanding of the system. It is inherent that no coding can begin until a sufficient level of detail has been reached in the design of at least some part of the system. The Top-Down Approach is done by attaching the stubs in place of the module. This, however, delays testing of the ultimate functional units of a system until significant design is complete. Bottom-up emphasizes coding and early testing, which can begin as soon as the first module has been specified. This approach, however, runs the risk that modules may be coded without having a clear idea of how they link to other parts of the system, and that such linking may not be as easy as first thought. Re-usability of code is one of the main benefits of the bottom-up approach.[citation needed]

Top-down design was promoted in the 1970s by IBM researcher Harlan Mills and Niklaus Wirth. Mills developed structured programming concepts for practical use and tested them in a 1969 project to automate the New York Times morgue index. The engineering and management success of this project led to the spread of the top-down approach through IBM and the rest of the computer industry. Among other achievements, Niklaus Wirth, the developer of Pascal programming language, wrote the influential paper Program Development by Stepwise Refinement. Since Niklaus Wirth went on to develop languages such as Modula and Oberon (where one could define a module before knowing about the entire program specification), one can infer that top down programming was not strictly what he promoted. Top-down methods were favored in software engineering until the late 1980s, and object-oriented programming assisted in demonstrating the idea that both aspects of top-down and bottom-up programming could be utilized.

Modern software design approaches usually combine both top-down and bottom-up approaches. Although an understanding of the complete system is usually considered necessary for good design, leading theoretically to a top-down approach, most software projects attempt to make use of existing code to some degree. Pre-existing modules give designs a bottom-up flavour. Some design approaches also use an approach where a partially-functional system is designed and coded to completion, and this system is then expanded to fulfill all the requirements for the project.

Programming

Top-down programming…(and so on) To get More information , you can visit some products about MYOB Accounting Software, Data Entry Software, . The Laser Cutting Machine products should be show more here!




By: himfryang