Some Basic Theories on Open System Interconnection Reference

The Open System Interconnection Reference Model or OSI Reference Model or OSI Model is basically a conceptual description for layered communications and computer network protocol design. It was created as part of the Open Systems Interconnection or OSI initiative. In its most fundamental form, it segments network architecture into seven distinct layers: the Application, Presentation, Session, Transport, Network, Data-Link, and Physical Layers. As a result it is frequently referred to as the OSI Seven Layer Model. A layer is a collection of theoretically similar functions that provide services to the layer directly above it and gets service from the layer beneath it. On each single layer an instance provides services to the instances at the layer above and requests service from the layer beneath. An example of this relates to a layer that provides error-free communications across a network which then provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that comprise the contents of the path.

Work on a layered model of network architecture commenced in the year 1977. Simultaneously the International Organization for Standardization or ISO started to develop its OSI framework architecture. OSI has two major parts: an abstract model of networking, called the Basic Reference Model or seven-layer model and a set of specific protocols. It is important to note that the standard documents that describe the OSI model can be freely downloaded from the ITU-T as the X.200-series of recommendations. A number of the protocol specifications can also be accessed as part of the ITU-T X series. The equivalent ISO and ISO/IEC standards for the OSI model are available from ISO, however not all of these are available free.

Every area of the OSI design evolved from experiences with the CYCLADES network, which also had a large influence on the design of the internet. The latest design has been meticulously documented in ISO 7498 and several of its addenda. In this latest model, a networking system is segmented into layers. Within each layer, one or more entities proves its functionality. Each entity will interact directly only with the layer just below it, and enables facilities for use by the layer above it. Protocols will allow an entity in one host to interact with a corresponding entity at the same layer in another host. Service definitions ideally describe the functionality provided to an (N)-layer by an (N-1) layer, where N is one of the seven layers of protocols operating in the local host.

Neither the OSI Reference Model nor OSI protocols designate any programming interfaces, other than a purposely abstract service specifications. Protocol specifications precisely define the interfaces between multiple computers, but the software interfaces within computers are implementation-specific.

Take for example, Microsoft Windows' Winsock, and Unix's Berkeley sockets and System V Transport Layer Interface, are interfaces between applications (Layer 5 and above) and the transport (Layer 4). NDIS and ODI are interfaces between the media in Layer 2 and the network protocol in Layer 3. Interface standards, with the exception of the Physical Layer to media, are estimated implementations of OSI Service Specifications.

Free to Air Satellite

FTA is in certain circumstances delivered by satellite television, but in many different locations of the world free-to-air television channels are actually broadcast unencrypted on UHF or VHF bands. Despite the fact that these channels are described as free, in some cases the viewer may have to pay for them. Some of these channels are paid directly by payment of a licence fee, for example as seen with the BBC or by voluntary donation for example PBS. Others indirectly pay by paying for consumer products and services where a portion of the cost is used for television advertising and sponsorship.
Free-to-air is typically used for international broadcasting, making it in some way a video equivalent of shortwave radio. Most authorized FTA retailers will list free to air channel guides and content available in North America for free to air use.

There are many competing systems presently in use. Many of the older channels used C-band satellite dishes of several feet in diameter to receive signals which were at first analogue microwaves, and then digital microwave using the 3.9-4.2 GHz band. Currently, in the 11.7-12.2 GHz Ku band permits the use of under one-meter dishes chiefly with the DVB-S standard. Hence FTA can now be used from apartment balconies.

The most prevalent North American sources for free-to-air DVB satellite television includes:


NASA TV Multi-channel(NASA HD, NASA Public, NASA Media, NASA Education) Broadcast on AMC 6 (72W)
Retro Television Network on AMC 9 (83W)
TVU Music channel and This TV on AMC 3 (87W)
ABC News Now on Galaxy 28 (89W)
Eternal Word Television Network on Galaxy 17 (91W)
My Family TV on Galaxy 3C (95W).
AMGTV and BYU Television on Galaxy 19 (97W)
English and foreign language broadcasters RT (TV network), MHz Worldview, Ebru TV, IRINN, Al Jazeera English and more up-linked by GlobeCast World TV on Galaxy 25 (97W)
Christian broadcasters The Word Network, Emmanuel TV, Daystar Television Network, JCTV, Trinity Broadcasting Network, The Church Channel, God's Learning Channel and more promoted by Glorystar & Spiritcast Satellite Systems TV on Galaxy 25 (97W)
Pentagon Channel on AMC 1 (103W)
Jewish Life Television, ResearchChannel, and University of Washington TV on Galaxy 18 (123W)
Montana Public Broadcasting Service on AMC 21 (125W)
Louisiana Connection Network on Galaxy 13 (127W)
White Springs Television on Galaxy 27 (129W)
Classic Arts Showcase on Galaxy 15 (133W)
Football, Basketball, Baseball, Soccer, and Hockey wildfeeds on various satellites

Many of these signals are carried by United States satellites. There is a small number of or no free Canadian DVB-S content available to users of medium-size dishes as much of the available Ku-band satellite bandwidth is used by pay-TV operators Shaw Direct and Bell TV, however the large style dish of over 3 feet/90cm does have a few extra choices. FTA signals may be dispersed across multiple satellites needing a motor or multiple LNBs to receive everything.


Free-to-air satellite TV is a feasible addition to any home video system, not only because of the specialized content it makes available but also for use in areas where terrestrial ATSC over-the-air reception is not at acceptable levels and additional channels are needed.

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Interconnetion Model Referance – The Open System

The Open System Interconnection Reference Model or OSI Reference Model or OSI Model is basically a conceptual description for layered communications and computer network protocol design. It was created as part of the Open Systems Interconnection or OSI initiative. In its most fundamental form, it segments network architecture into seven distinct layers: the Application, Presentation, Session, Transport, Network, Data-Link, and Physical Layers.

As a result it is frequently referred to as the OSI Seven Layer Model. A layer is a collection of theoretically similar functions that provide services to the layer directly above it and gets service from the layer beneath it. On each single layer an instance provides services to the instances at the layer above and requests service from the layer beneath. An example of this relates to a layer that provides error-free communications across a network which then provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that comprise the contents of the path.

Work on a layered model of network architecture commenced in the year 1977. Simultaneously the International Organization for Standardization or ISO started to develop its OSI framework architecture. OSI has two major parts: an abstract model of networking, called the Basic Reference Model or seven-layer model and a set of specific protocols. It is important to note that the standard documents that describe the OSI model can be freely downloaded from the ITU-T as the X.200-series of recommendations. A number of the protocol specifications can also be accessed as part of the ITU-T X series. The equivalent ISO and ISO/IEC standards for the OSI model are available from ISO, however not all of these are available free.

Every area of the OSI design evolved from experiences with the CYCLADES network, which also had a large influence on the design of the internet. The latest design has been meticulously documented in ISO 7498 and several of its addenda. In this latest model, a networking system is segmented into layers. Within each layer, one or more entities proves its functionality. Each entity will interact directly only with the layer just below it, and enables facilities for use by the layer above it.

Protocols will allow an entity in one host to interact with a corresponding entity at the same layer in another host. Service definitions ideally describe the functionality provided to an (N)-layer by an (N-1) layer, where N is one of the seven layers of protocols operating in the local host.

Neither the OSI Reference Model nor OSI protocols designate any programming interfaces, other than a purposely abstract service specifications. Protocol specifications precisely define the interfaces between multiple computers, but the software interfaces within computers are implementation-specific.

Take for example, Microsoft Windows' Winsock, and Unix's Berkeley sockets and System V Transport Layer Interface, are interfaces between applications (Layer 5 and above) and the transport (Layer 4). NDIS and ODI are interfaces between the media in Layer 2 and the network protocol in Layer 3. Interface standards, with the exception of the Physical Layer to media, are estimated implementations of OSI Service Specifications.

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Tips and Techniques About Green Architecture

As more and more people become interested in the effect they are having on our environment, the ability to design and construct buildings that are energy efficient and environmentally friendly is becoming more important. This area of design is called green architecture and is a growing trend amongst those wanting to live in harmony with their environment and those wishing to conserve traditional energy resources.
Green architecture aims to work in harmony with the natural features that surround the location of the project, to use construction materials that can be easily grown or that have been recycled and to maximise the energy efficiency of the building. This has benefits for both the environment and for the occupants of the building.

Green architecture should use the natural ecology of the planet as a macro model and green architects should always keep the environment in mind when designing. Listening to a client and transforming their needs into a workable, energy efficient and environmentally friendly design is a skill and one that you should ensure your choice of green architect has.

A building designed using green architecture will reduce energy bills, use less water and will reduce the amount of waste being added to landfill sites. There are a variety of ways through which these savings are achieved.

One of the best known methods of reducing energy bills is to have solar panels installed. There are many benefits to using solar panels ranging from low maintenance and versatility to it being non-polluting and a renewable energy source. After the initial installation, there are relatively few ongoing costs. No moving parts mean low maintenance and the heat and light from the sun is free!
Another method used in construction of green architecture is thermal mass. Insulated Concrete Forms (ICFs) produce a framework when locked together much like Lego bricks. This framework forms a permanent and integral part of the building and is pumped full of concrete that has been composed and cured to reduce its thermal conductivity. This produces the thermal mass required to reduce the effects of outside temperature fluctuations on the ambient temperature inside the building thus reducing energy bills.

The use of recycled materials is becoming increasingly popular, as is the use of green materials. Recycled materials include glass, plastic and tyres while green materials include wood, stone and earth. Using these recycled resources helps to reduce the waste being sent to landfill sites and the use of the green, more natural resources helps our buildings blend more harmoniously with their environs.

These techniques are just some of the ways that green architecture is helping to make our buildings much more sustainable and environmentally friendly. For example water, mud, rammed earth and logs can all be utilised to provide thermal mass to a building instead of ICFs. Which one is right for your project should be determined by the environment around the location of the building and the immediate ecology of the area. Discussions with your green architect will help you decide how to proceed.

Other techniques involved with green architecture are maybe not so well known generally but your green architect should mention them as they all help to add to the energy efficiency of a project, for example:
Using locally sourced materials reduces the cost and use of fuel for transportation and if trees are felled to make room for your project then this wood could be put to good use in the construction.
Recycling grey water (waste water from baths, showers and wash hand basins) can be captured, stored and treated to a standard suitable for WC flushing.
Rainwater harvesting can be as simple as a water butt under a downpipe or a more complex over or underground tank depending on your use for the water which can be anything from watering your garden or cleaning your car to flushing your toilet or having a shower.
Small scale wind turbines can be used to generate energy to charge small batteries with applications such as lighting and electric pumps.

Many opportunities exist for all of us to start living in a way that is more in harmony with our surroundings. Whether you want to light your garden using solar power, generate wind energy to light your caravan or build a home from scratch that is environmentally friendly, energy efficient and at one with nature we can all add to the conservation of our planet.
Green architecture is the way to release ourselves from the grip of fossil fuels into the hands of renewable energy, green architecture is the future of us and of this planet.


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N-tier Client-server Architecture- An Overview

N-tier architecture is an application structure wherein the work for the servers (service- providers) and clients (service requesters) are separated to ease developers in developing web applications. The structure includes a number of levels arranged one upon another and each level is allocated for distinct set of task. Also known as multi-tier architecture, this client-server architecture includes separate sections for presentation, application processing and data management processes.
It is often seen that both clients and servers undergo communication over a common computer network but by using separate hardware. The computing system of the service providers (server) host a number of programs to be shared with the clients. On the contrary, a client may not share any of its personal resources with the server machine and instead, may send incoming request for services from the server. Here lies the use of N-tier client-server architecture which lays down a model for web developers to create customized web applications as per the specific business requirements.
A major benefit of using N-tier architecture is that web developers can easily separate the applications into multiple tiers and can modify them rather than rewriting the entire application. Furthermore, the applications are loosely connected with each other and changes made in one application do not hamper performance of others.
Generally, web application developers use 3-tier application, which includes a programming tier, a logic tier and a data tier. The user interface programming tier translates task to help user easily understand the information related to services. This topmost level of the application structure interacts with other tiers by providing results to all other tiers in the computing network. The logic tier controls the functioning of the application by processing commands, evaluating and calculating specific data. The information from programming layer is later stored in the database servers of the data tier. The stored information is then transferred back to the logic tier for further processing and ultimately to the users computer system.
Web applications meant for e-commerce websites are popular examples of N-tier client-server architecture. If you want to have web-application created out of using N-tier application program, then you can seek assistance from software development companies. There are a few software development companies which have skilled engineers to provide flawless combination of various layers for N-tier client-server architecture. You can also hire some offshore web developers who are experienced in handling database including Oracle, SQL Server, MySQL and MS Access.
So, spare out some time to find reliable software development companies and hire web developers to get web applications created out of N-tier client-server architecture.

The computing system of the service providers (server) host a number of programs to be shared with the clients. On the contrary, a client may not share any of its personal resources with the server machine and instead, may send incoming request for services from the server. Here lies the use of N-tier client-server architecture which lays down a model for web developers to create customized web applications as per the specific business requirements.

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AutoCAD Technology What is difference between 3d and 4d CAD

Till now 3d cad technology is predominant. Recently researchers at Stanford University spending much time on projects about 4d technologies. Every technology try to upgrade constantly and cad is no different.
The new 4d technology is much emphasized on empowering project managers and engineers role in managing and minimizing risk throughout all stages of a construction project; effectively communicate the design, schedule, and other project data and rapidly explore design and construction alternatives.
During 1990s 2d and 3d model of cad means advancement in visual representation of cad designs. It is just limited to graphics. At large we can access designs in various formats. The concept of 2d and 3d is just about animation and formats.
But 4d is a breakthrough of this decade. Researchers are mainly into bringing solution for core problem on functionality. Functionality to generate and manipulate model-based project data specifically object-models of the construction project.
Through 4d technologies one can generate multi views and clearly communicate the spatial and temporal aspects of construction schedules to all project participants. Planners, designers, and engineers will use 4D environments to visually relate data much like the way engineers use gradated color 3d models to visualize the stresses on structures.
The thought process is to produce object models of construction project visually in effective mode on the desktop, and in a web-browser. Now planners also can go for a visual-basic macro in Excel and a set of MaxScripts in 3D Studio Max.
4d technology indeed will bring smile on planners and cad analysts face as much importance also given to organization of models. Placing the geometric information in one layer onto two or more layers regrouping CAD components found on several layers onto a different set of layers. Breaking a component into smaller pieces and putting the pieces on separate layers. These above are main features of 4d technology.
Having said there are few challenges still to be solved. utilizing and extending current industry standard efforts such as STEP and IAI, the 4D simulation/visualization progresses and large displays vs. desktop displays
With the help of tools 4d cad has to undergo process that contain importing the schedule data into the Java 4D application, importing the CAD data into the Java 4D application, organizing the CAD data into appropriate groupings, linking the components to the activities, assigning action-types and exporting 4D model to CAVE and to Java 4D applet. It’s easy to import the 4D associations exported from the Java 4D application.
Much improvements and upgrades can be seen in scheduling too. Typically 3d cad involves generating and naming activities, assigning durations to activities, sequencing activities but this time 4d hasn’t left behind in these aspects. This involves association of cad components and activities through lists of names or hierarchies, or by pointing to and clicking on graphical representations of activities. Now the software can automatically link many projects that have naming conventions for activities in Primavera. Even a planner could perform the assembly sequence within the 4D environment, and the 4D tool would record the assembly sequence in a much more interactive way, similar to how today's recording macro features work.

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Model Train Track, The steps you should know

Model train track is measured in gauges, that coincide a great deal with the scale of the model train. for instance, 'N' scale is one sixtieth of the size of a full size train.
The 'N' stands for nine, which means the 9mm, the distance between the inside of the tracks. These tracks are small, and many of these train layouts will fit in a rather small space.
It is also a good size if you are thinking about running long strings of cars, since the train cars will be lighter, they will use less electricity. You could read about all the different train rail gauges, and there are plenty of great, highly detailed specifications, drawings, and layouts.
If you are a beginner, or just a casual hobbyist you don't have to get so technical. You do want to learn the basics the scale letter also give what standard gauge it is. Your most popular scale, HO, has a track width of 16.5mm, or 5/8th of an inch.
There may be other gauges for HO, but they will be clearly defined, like 'HON3.' This means that it is HO scale, but has a narrow gauge, and the track gauge is three scale feet wide, rather than the standard real life gauge of 4', 8" long.
Sounds really confusing doesn't it? Don't worry about that as long as you are sticking to standard scales.
The only time you may have to deal with this more is when you start getting up into larger model train track gauges, for of 1/8 scale model trains. This is really where you have to start dealing with heavy, weight bearing tracks.
When you first get your kit or set and want to set up your track design, it is a good idea to open the individual pieces, lay them out on your work surface, and look at the instruction manual. Look at the different designs they have included and lay out the tracks, without attaching anything as of yet.
You will want to make sure that the tracks lay flat, and don't have any warps in them. Check that the connecting ends are in good condition, and that the switch controllers function smoothly and will fit snugly together.
If you are a beginner, you should be using EZ-Track, or Tru-Track, so these parts should all just snap together. Now before you hook up anything else, you should make sure you are using a clean sturdy flat surface, even if you are just putting it together to make sure it works.
Now no matter what kind of system you use, you will have terminal joiners that will have to have wires connected to them. While some Lionel sets include three rail terminals, most common ones have only two.
It is a good idea to just use the standard screws that come with it, even if you plan to permanently connecting them. For convenience, many new sets just 'plug in,' meaning you just strip the ends of the wires and put it in the plug, no muss no fuss.
For obvious safety reasons, make sure that everything is unplugged before you start working with the electrical aspects of laying track. Then you're ready to go.

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Using advance technology in Modern Building Design

In recent years, the methods of designing and constructing buildings have undergone many progressive changes. Our future and the future of our environment are now being taken into consideration when designing buildings. Current technology is allowing companies to build for the future.
A method known as Building Information Modeling (BIM) has been developed as a means of collecting interconnected computable information about a building. Because information is continuously being collected as a building project develops, dependable digital representations of the building are always available for review by all parties involved in the design. BIM creates one central model of a design which is available to all design and construction teams so they are all on the same page as the building progresses. This allows for better communication as it relates to making modifications and resolving problems.
'Green' designs have become a thriving industry. Using technology and innovation, many buildings are now being designed to have the least impact on the environment. Such deigns include recycled material used in constructing the building, green rooftops, a wastewater recycling plant, solar power, on-site power generators, materials that allow water to be captured from the outdoors and get filtered for indoor use. As well, buildings are being designed to use sunlight as much as possible. Using renewable energy technologies and conservation technologies are a major factor when designing modern buildings.
The use of computer-based tools to solve design problems is another way that technology is changing the way the modern building is designed. Using computer technology, building designers can simulate conditions before the building has been constructed. This can include simulating events such as an earthquake.
Buildings are now being designed to meet the ever changing technological advancements. For instance, re-radiating systems (IRS) and distributed antenna systems (DAS) are being installed in large buildings where steel, concrete, and other building materials obstruct radio signals. IRS and DAS boost signals that support cell phones, emergency services radio systems, and personal communications devices. The result is improved safety for building users.
Because much of the workforce either works at home or are on the go, designers are now designing buildings to support wireless technologies. Workers will have the ability to access the Internet, access materials and files from anywhere in the building or while they are away from the building. For instance, some hospitals are conducting patient charting using wireless devices. As well, old and new buildings are now being retrofitted to support wireless technology.
Since our world has become a much more dangerous place, technology is now being used to create safer and stronger building structures. To protect people from those who wish to do us harm, designers are now implementing principles of blast-resistant designs. Buildings are now being designed to sustain and contain a certain amount of bomb damage. This includes preventing a wide-spread collapse of a building, limiting damage to a small area, and reducing the amount of glass and debris spread from a bomb blast.
Advancements in technology are improving how the modern building is being designed and built. Designers are now taking the safety of the occupants and the impact on the environment into consideration when designing a building. Technology is ensuring that these new buildings are being built for future sustainability.

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