PRINCIPLE OF REMOTE SENSING

PRINCIPLE OF REMOTE SENSING

A) ELECTROMAGNETIC RADIATION

Ø The Energy is either come from the natural source sun or from various artificial sources. It is known as electromagnetic Radiation as this energy consists not only an Electrical field but also a magnetic field.

a)    Electrical Field (E): This field is generated perpendicular to the direction of radiation traveling.

b)    Magnetic Field (M): It is exactly oriented at right angles toward the electrical field.

Ø Electromagnetic energy can be described in terms of its velocity, frequency and wavelength.

Ø Energy waves travel similar to the speed of light, c, which is approximately equal to 3×10^8 m/s.

Ø Wavelength λ of the wave is the distance from any point on one wave to a similar position on the next wave which means between two successive peaks.

Ø The wavelengths most of used in remote sensing are very short. It is normally expressed in micrometers (μm). 1 μm is equal to 1×10-6 m.

Ø  Frequency f is the no of waves passing a fixed point per unit of time. It is generally expressed in Hertz (Hz). This implies that wavelength (λ) and frequency (Hz) are inversely related where c is a constant. The important fact is that always longer wavelengths have smaller frequencies compared to shorter wavelengths.

Ø The Electromagnetic energy interacts with the earth’s surface and various features like bared soil, buildings, grass, vegetation, water bodies, and forests etc.

Ø The Response from the ground earth's surface to incoming energy is the reflection, and the all energy emitted by all objects as a function of temperature & structure is the emittance.

B)  ELEMENTS OF REMOTE SENSING

1)    Source of Illumination/ Energy: The important requirement for any remote sensing process is to have an energy of source which illuminates and provides electromagnetic radiation to the target of interest on the earth surface.

2)    Radiation and the Atmosphere: Energy is reached at any point in the atmosphere as it passes through. This type of interaction may take place 2^nd time as the whole energy travels from the target on the ground and again back to the sensor. Atmosphere modifies the wavelength & Spectral distribution of energy to some extent level.

3)    Interaction of Energy with the Target: Once the energy in the form of radiation makes its path to the target level through the atmosphere, it strikes the target depending on the characteristics and features of both the target (object) & the radiation. Whenever energy received by the object interacts here it is either transmission, absorption, scattering, emitted or reflected from the target.

4) Recording of Energy by Sensor: Moving further the energy has been scattered or emitted from the target, the sensor is required to collect, receive and record the electromagnetic radiation (EMR). Return Signal is adjusted to a sensor that actually responds to various types of wavelengths.  

5) Transmission, Reception, and Processing: The energy which was recorded by the active or passive sensor has to be transmitted, often in the form of electronic, to a receiving and processing ground station where the actual data are processed into a satellite image could be available in the hardcopy as well as in the digital format.

6) Interpretation and Analysis: The processed satellite image is interpreted visually, digitally, or else electronically, to extract all kinds of information and data regarding the target or earth object which was illuminated.

7)  Users and application: The final purpose of remote sensing technology is achieved when the useful important information is extracted in the desired form. Afterward, any scientist or assistant could resolve a particular problem.

  

TRANSPARENT WOOD AS A BUILDING MATERIAL

HISTORY OF TRANSPARENT WOOD

For the first time, transparent wood was created in the year 1992 by a German scientist Siegfried Fink. A research group by two Professor Lars Berglund from Swedish KTH University and Professor Liangbing Hu from the Maryland University has developed a technique to remove the color and different chemicals from the wooden piece, possible by adding polymers like Poly (methyl methacrylate) and epoxy, at the cellular level, thereby rendering them transparent in the 2015-2016 year.

THE MANUFACTURING PROCESS OF TRANSPARENT WOOD

 

In its natural state, wood is not a transparent material because of its properties like scattering and absorption of light. The tannish color in wood is due to its chemical components of the polymer composition of cellulose, hemicellulose, and lignin. The wood's lignin is drastically responsible for it's distinctive or brownish color. The amount of lignin determines by the levels of visibility in the wood, around 80-95%. To make wood a visible and transparent, both absorption and scattering need to be reduced in its product creation. The manufacturing process of this type of wood is based on removing all the lignin called the delignification procedure.

It is produced by treating and compressing the wooden strips. The normal way to manufacture transparent wood is to take a piece of the wooden block and place it in a bath of boiled water, Sodium hydroxide, and Sodium sulfite. The next step is to just let it remain soaked there for about 12 hours. This procedure strips away all the opaque stuff and leaves behind floppy transparent structural cellulose.

Once you get rid of all the cellulose, sink the wooden piece into a bath of hydrogen peroxide which will further bleach it a little more. Both these steps are apparently the standard method used to create paper thereby making it look smooth and white. This process leaves behind bone-white wood fibers. The wood looks crunchy after the process since the lignin is “nature’s glue”.

The final step is to transfer all the cellulose and bubble epoxy in a vacuum chamber. Wood is basically put under a vacuum and is later smothered with clear epoxy. The tubes that are made of wood fibers soak up the epoxy resin. When it dries up transparent wood is obtained. Wood grains are even visible on it, but it is incredibly tough.

ADVANTAGES OF TRANSPARENT WOOD

1) One of the major Pros of transparent wood in the comparison of the typical glass its structural properties like ductility and resistance to fracture is higher. It is almost transparent as a glass but it has higher strength compare with any glass.

2) It is a better biodegradable material in comparison with any plastic.

3) It can be used to create highly strong and energy-efficient windows.

4) According to ‘D. Katunsky’ et. al. (Structural Elements with Transparent Wood in Architecture), transparent wood sets the path for greener architecture and better electronics.

DISADVANTAGE OF TRANSPARENT WOOD

The only drawback that can be pointed out with this type of wood is; the epoxy isn’t environmental or eco- friendly. Currently, it is only possible to make it in the labs. But the engineers are very confident that soon they will be able to replace the epoxy with recyclable plastic and scale the procedure. It means that in the future the buildings partly made with transparent wood shall be dominant.

APPLICATION OF TRANSPARENT WOOD

1) Transparent wood roofs can be designed to some of the buildings for providing uniform and comfortable illumination as compared to any conventional glass.

2) In addition, Panels can be built from this type of wood which exhibits lower thermal conductivity, better impact strength, and lower density as compared to any glass.

3) Functionalized transparent wood provides even better opportunities for smart buildings. By the inclusion of quantum dots, transparent wood attains diffused luminescence properties. It can be used in planar light sources, luminescent building components, or designed furniture.

4) In order to provide electromagnetic interference shielding to the transparent wood, magnetic nanoparticles have been incorporated into it.

5) Another important application of transparent wood is; it is used as a structural material for some of the photovoltaic devices such as electrochromic devices and solar cells. Because of the high haze, transparent wood can be designed as a light-diffusing layer. Furthermore, high haze means large scattering angles, which increase the length of the light path inside solar cells, so that efficiency is improved.

6) The devices exhibit a vibrant magenta-to-clear color change with a high coloration efficiency and low driving voltage. This entire concept will contribute to smart windows, which in turn saves energy.

7) Transparent wood can be used on façades in cases where there is a requirement for sunlight to illuminate the interior, but privacy is equally important. It is because of the high values of optical haze in transparent wood, which lets the light in, but clouds the view; it can be used for those peculiar cases.

CONCLUSION

Transparent wood is a very important topic in the emerging field of wood nanotechnology – both in the academics and in the industrial field. Noticeable progress has been made which includes manufacturing of this wood with improved all mechanical properties, producing large & thicker transparent wood structures, along with the realization of this type of wood fictionalization. In-depth of study is required to understand the light–wood interaction to tune the optical properties and mechanical properties, improve the green aspect and to explore advanced transparent wood applications and uses.

Transparent wood is a newly invented material. Currently, it is a topic of research and undergoing various experiments, but it certainly holds great potential for becoming an important building material. Its translucency along with its outstanding mechanical properties is making it an interesting choice for using in façades and for that fact, it is gradually paving its way towards being listed as a structural material in the field of construction.

ADVANTAGES & DISADVANTAGES OF GIS

ADVANTAGES & DISADVANTAGES OF GIS

ADVANTAGES OF GIS

• GIS technology has the capability of improving organizational integration. This technology can be integrated with software, hardware, and also data in order to capture, analyze, manage, and display all information geographically referenced.
• This technology allows viewing, questioning, generating query, understanding, visualizing and interpretation of the data into different ways which will help in the reveal relationships, trends, and patterns in the form of graphs, globes, maps, charts, tables and reports.
• It will be most helpful for solving problems throughout looking at the data in a way which is easily and quickly shared.
• GIS technology provides very accurate data.
• Using this technology we can able to better predictions and analysis.
• It will help to take better decisions made by government authorities.
• Improve decision making with the help of layered by layered information in the software.
• With the help of GIS, we can easily identify communities that is under risk or lacking infrastructure.
• It will also help in identifying criminology matters.
• Better management of natural resources of the country.
• Better communication during any critical emergency situation.
• We can able to save cost because of a better decisions.

DISADVANTAGES OF GIS

• This technology might be considered as expensive because of specialized computer equipment and software.
• GIS data are very expensive than traditional data.
• Collecting the data can be very time-consuming.
• Privacy and security issues can sometimes limit distribution of data.
• GIS data may also be subjects misuse or misinterpretation.
• Learning time on GIS the software can be very long.
• GIS shows spatial relationships but does not necessarily provide absolute solutions for them.
• Integration with traditional maps is difficult in GIS.
• It requires efficient processor and higher storage space.

  NOTES: In short, we can say that there is a real fact that GIS technology has the capability to offer both advantages and disadvantages to everybody. From the above-mentioned points, we can conclude that there is still great potential if GIS technology is used apart from the idea of some disadvantages and in this generation, the use of GIS technology is a great opportunity to experience its best way.