Tuesday, December 24, 2013

Virtual water



Virtual water trade (also known as trade in embedded or embodied water) refers to the hidden flow of water if food or other commodities are traded from one place to another. For instance, it takes 1,600 cubic meters of water on average to produce one metric tonne of wheat. The precise volume can be more or less depending on climatic conditions and agricultural practice. Hoekstra and Chapagain have defined the virtual-water content of a product (a commodity, good or service) as "the volume of freshwater used to produce the product, measured at the place where the product was actually produced".[1] It refers to the sum of the water use in the various steps of the production chain.
Professor John Anthony Allan from King's College London and the School of Oriental and African Studies introduced the virtual water concept,[2] to support his argument that countries in the Middle East can save their scarce water resources by relying more on import of food. For his contributions he was awarded the 2008 Stockholm Water Prize.[3] Allan stated: "The water is said to be virtual because once the wheat is grown, the real water used to grow it is no longer actually contained in the wheat. The concept of virtual water helps us realize how much water is needed to produce different goods and services. In semi-arid and arid areas, knowing the virtual water value of a good or service can be useful towards determining how best to use the scarce water available."
There are, however, significant deficiencies with the concept of virtual water that mean there is a significant risk in relying on these measures to guide policy conclusions. Accordingly, Australia's National Water Commission considers that the measurement of virtual water has little practical value in decision making regarding the best allocation of scarce water resources


Virtual water trade refers to the idea that when goods and services are exchanged, so is virtual water. When a country imports one tonne of wheat instead of producing it domestically, it domestically, it is saving about 1,300 cubic meters of real indigenous water. If this country is water-scarce, the water that is 'saved' can be used towards other ends. If the exporting country is water-scarce, however, it has exported 1,300 cubic meters of virtual water since the real water used to grow the wheat will no longer be available for other purposes. This has obvious strategic implications for countries that are water-constrained such as those found in the Southern African Development Community (SADC) area [4][5][6]
Water-scarce countries like Israel discourage the export of oranges (relatively heavy water guzzlers) precisely to prevent large quantities of water being exported to different parts of the world.
In recent years, the concept of virtual water trade has gained weight both in the scientific as well as in the political debate. The notion of the concept is ambiguous. It changes between an analytical, descriptive concept and a political induced strategy. As an analytical concept, virtual water trade represents an instrument which allows the identification and assessment of policy options not only in the scientific but also in the political discourse. As a politically induced strategy the question is, whether virtual water trade can be implemented in a sustainable way, whether the implementation can be managed in a social, economical and ecological fashion, and for which countries the concept offers a meaningful option.
The data that underlie the concept of virtual water can readily be used to construct water satellite accounts, and brought into economic models of international trade such as the GTAP Computable General Equilibrium Model.[7] Such a model can be used to study the economic implications of changes in water supply or water policy, as well as the water resource implications of economic development and trade liberalisation.
In sum, virtual water trade allows a new, amplified perspective on water problems: In the framework of recent developments from a supply-oriented to a demand-oriented management of water resources it opens up new fields of governance and facilitates a differentiation and balancing of different perspectives, basic conditions and interests. Analytically the concept enables one to distinguish between global, regional and local levels and their linkages. This means, that water resource problems have to be solved in problemsheds[8][9] if they cannot be successfully addressed in the local or regional watershed. Virtual water trade can thus overcome the hydro-centricity of a narrow watershed view. According to the proceedings of a 2006 conference in Frankfurt, Germany, it seems reasonable to link the new concept with the approach of Integrated Water Resources Management.

Limitations of the virtual water measure

Key shortcomings of virtual water measures are that the concept:
  1. Relies on an assumption that all sources of water, whether in the form of rainfall or provided through an irrigation system, are of equal value.[10]
  2. Implicitly assumes that water that would be released by reducing a high water use activity would necessarily be available for use in a less water-intensive activity. For example, the implicit assumption is that water used in rangeland beef production would be available to be used to produce an alternative, less water-intensive activity. As a practical matter this may not be the case, nor might the alternatives be economic.[10]
  3. Fails as an indicator of environmental harm nor does it provide any indication of whether water resources are being used within sustainable extraction limits. The use of virtual water estimates therefore offer no guidance for policy makers seeking to ensure that environmental objectives are being met.[10]
The deficiencies with the concept of virtual water mean that there is a significant risk in relying on these measures to guide policy conclusions. Accordingly, Australia's National Water Commission considers that the measurement of virtual water has little practical value in decision making regarding the best allocation of scarce water resources.[11]
Other limitations more specific to the MENA (Middle East & North Africa) region include:
  1. In MENA rural societies, farmers are by tradition politically influential and would prohibit new policies for water allocation. Reallocating the water resources adds a huge burden on the farmers especially when a large portion of those farmers use their land for their own food consumption which happens to be their only source of food supply.[12]
  2. Importing food could pose the risk of further political dependence. The notion of "Self Sufficiency" has always been the pride of the MENA region.[13]
  3. The use of virtual water lies in the religious regulations for charging for water. According to Al-Bukhari, Prophet Mohammad’s teachings, the Prophet said: “People are partners in three: Water,Herbs and Fire” (referring to basic energy resources). Therefore, and because farmers are generally poor and rain water, rivers and lakes are like a gift from God,the MENA countries might find it difficult to charge the farmers the full cost for water.[13]

Water Footprint

The concept of virtual water trade was introduced to refer to the idea that countries can save domestic water by importing food. Imported food, however, comes from somewhere. In 2002, professor Arjen Y. Hoekstra, at the time working for UNESCO-IHE, now at University of Twente, the Netherlands, introduced the concept of water footprint. The water footprint shows the link between consumer goods or a consumption pattern and water use and pollution. Virtual water trade and water footprint can be seen as part of a bigger story: the globalization of water.



Thanks to :
Wikipedia



How Potable Water Rises to the Top of Skyscrapers








In the 1950’s, pneumatic pressure tank systems replaced many roof tank systems. These systems put the pneumatic tank inside the building, eliminating the pigeon problem. The pumping equipment pumped water to the pneumatic
tank pressurized by an air compressor that supplied water to the floors. The systems, for the most part, worked well if properly maintained, but required large areas for equipment installation and were expensive to install. In addition, these systems were big consumers of energy given they ran at a constant speed, despite low demand periods where water is hardly used.



The Present Today, water pressure systems, or booster systems, have come a long way since the early days of pigeon-infested roof tanks. Now building owners have many control and pumping options that solve any pumping application while saving on energy costs and space. Booster systems, such as the one marketed by Metropolitan Industries in Romeoville, now come prefabricated and skid-mounted, which allows for ease of installation and provides many design solutions to meet constrictive space requirements. Building owners can now choose from state-of-the-art variable speed control, which cuts energy bills in half over the life of the system while increasing system life by years. Other advances in technology include touch-screen panels
allowing operators to make system adjustments with the touch of a finger, ability to interface into existing building automation systems and “smart pump technology” that allows booster systems to continually self-diagnose itself and alert the operator to any problems.


Thanks to: Mark Brickey, Paul Larson, P.E. & Joseph Sanchez of Metropolitan Industries
 
How Potable Water Rises to the Top of Skyscrapers

By Mark Brickey, Paul Larson, P.E. & Joseph Sanchez of Metropolitan Industries (Information compiled by Gunnar Collins, IPP, FASSE, Collins Backflow Specialists, Inc.)

Wednesday, December 18, 2013

Frame Sizing Guidelines



Frame Sizing Guidelines

How to know your Face Size?

Simplest method: -
  • Go for a MEDIUM SIZE frame because it suits 98% of Indian faces.
  • If it does not fit, we will pick it up very quickly (no-questions asked) at Zero cost and you will get FULL MONEY BACK.
  • We have shipped over 12 Lac orders and less than 2% people have needed to return.
  • Lot of frames also have Model Shots on Real Faces - these give a very good idea of frame size.
  • Kids less than 10 years must go for Kid Size Frames. Between 10-14 years Kids should go for Small Size Frames.
Use our Frame Size Tool: -
Traditional Method: -
Looking into your mirror, hold a ruler so it is lined up with each temple. Measure in inches
the distance between your left and right edges(temple area).
Face Size (temple to temple)
Suggested Frame/Sunglasses Size
   
Below 115mm or Below 4.5”
Small
115mm or 4.5”
Small
121mm or 4.75”
Medium
127mm or 5”
Medium
130mm or 5.125
Medium
135mm or 5.25”
Medium
140mm or 5.5”
Medium
146mm or 5.75”
Medium
152mm or 6”
Large
Above 152mm or Above 6”
Large

 

How to know your Existing Frame Size?

Use our Frame Size Tool: -
Or follow Instructions below: -
When selecting eyeglasses or sunglasses at Lenskart.com, it's helpful to know what size frame will fit you. You can find this information easily by looking at a pair of frames you may currently own, or by visiting a local optical store.
In the event you already have a pair of frames that you would like to purchase again or even find a pair of frames similar, you can quickly identify the designer name, model number, and frame size by simply looking on the inside of your eyeglass temples (arm pieces). Below you'll find a quick guide to helping you identify your eyeglasses.

Components of Frame Size:

Eye Size:
Measured from outermost edges of lenses horizontally.
Approximately 40 mm. - 62mm.
Bridge Size:
The distance between lenses.
Approximately 14 mm. - 24 mm.
Temple Length:
Length of temple piece - also know as the arm piece or ear piece.
Approximately 120 mm. - 150 mm.

Frame Size

In most cases the frame size is calculated as per below range
Frame Size
Eyeglasses
Sunglasses
Small
Below 48 mm
Below 55mm
Medium
48 mm- 55 mm
56 mm- 64 mm
Large
Above 55 mm
Above 64 mm
Please note that for some Eyeglasses/Sunglasses the frame size may not follow the above convention
Thanks to :