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Friday, 10 February 2012

Green Cloud

Green computing is defined as the atudy and practice of designing , manufacturing, using, and disposing of computers, servers, and associated subsystems—such as monitors, printers, storage devices, and networking and communications systems—efficiently and effectively with minimal or no impact on the environment." The goals of green computing are similar to green chemistry; reduce the use of hazardous materials, maximize energy efficiency during the product's lifetime, and promote the recyclability or biodegradability of defunct products and factory waste. Research continues into key areas such as making the use of computers as energy-efficient as possible, and designing algorithms and systems for efficiency-related computer technologies.

There are several approaches to green computing,namely

• Product longetivity

• Algorithmic efficeincy

• Resource allocation

• Virtualisation

• Power management etc.

Need of Green Computing in Clouds

Modern data centers, operating under the Cloud computing model are hosting a variety of applications ranging from those that run for a few seconds (e.g. serving requests of web applications such as e-commerce and social networks portals with transient workloads) to those that run for longer periods of time (e.g. simulations or large data set processing) on shared hardware platforms. The need to manage multiple applications in a data center creates the challenge of on-demand resource provisioning and allocation in response to time-varying workloads. Normally, data center resources are statically allocated to applications, based on peak load characteristics, in order to maintain isolation and provide performance guarantees.

Until recently, high performance has been the sole concern in data center deployments and this demand has been fulfilled without paying much attention to energy consumption. The average data center consumes as much energy as 25,000 households [20]. As energy costs are increasing while availability dwindles, there is a need to shift focus from optimising data center resource management for pure performance to optimising for energy efficiency while maintaining high service level performance. According to certain reports, the total estimated energy bill for data centers in 2010 is $11.5 billion and energy costs in a typical data center double every five years.

Applying green technologies is highly essential for the sustainable development of cloud computing. Of the various green methodologies enquired, the DVFS technology is a highly hardware oriented approach and hennce less flexible. The reuslt of various VM migration simulations show that MM policy leads to the best energy savings: by 83%, 66% and 23% less energy consumption relatively to NPA, DVFS and ST policies respectively with thresholds 30-70% and ensuring percentage of SLA violations of 1.1%; and by 87%, 74% and 43% with thresholds 50-90% and 6.7% of SLA violations. MM policy leads to more than 10 times less VM migrations than ST policy. The results show flexibility of the algorithm, as the thresholds can be adjusted according to SLA requirements. Strict SLA (1.11%) allow the achievement of the energy consumption of 1.48 KWh. However, if SLA are relaxed (6.69%), the energy consumption is further reduced to 1.14 KWh. Single threshold policies can save power upto 20%,but they also cause a large number of SLA violations. Green scheduling algorithms based on neural predictors can lead to a 70% power savings. These policies also enable us to cut down data centre energy costs, thus leading to a strong,competitive cloud computing industry. End users will also benefit from the decreased energy bills.

Control Of Corrosion On Underwater Piles

Piles are structures used to transfer loads from superstructure to the sub surface strata. When the subsurface stratum is water based or if we deal with a hydraulic structure, the piles are to be driven into water and under water strata. Piles used in underwater structures are often subjected to corrosion. There is no absolute way to eliminate all corrosion; but corrosion protection measures are employed to control the effect of corrosion. Corrosion protection can be in different ways according to the environment and other factors. Forms of corrosion protection include the use of inhibitors, surface treatments, coatings and sealants, cathodic protection and anodic protection. The control measures explained in this are Protective coatings, cathodic treatment and application of Fibre Re-inforced Polymer (FRP) Composites

Corrosion Mechanism Of Steel In Sea Water

On steel piling in seawater, the more chemically active surface areas (anodes) are metallically coupled through the piling itself to the less chemically active surface areas (cathodes) resulting in a flow of electricity and corrosion of the anodic areas. General surface roughening occurs when these local anodic and cathodic areas continually shift about randomly during the corrosion process. Sometimes these active local areas do not shift position end, therefore, the metal suffers localized attack and pitting occurs. In general, the depth of pitting is related to the ratio of the anodic sites to the area of cathodic site in contact with the electrolyte (seawater). The smaller the anode area relative to the cathode area, the deeper the pitting

Corrosion Management

Before deciding on the methods for control of corrosion to be applied, conceptual and feasibility studies have been carried out. Typically, corrosion management can be divided into three major phases.

Phase 1 of the program is the programmatic assessment of the project. This phase is the planning stage for a corrosion management program to take place. It initiates the program to be implemented on structures that are found to be under the threat of corrosion. For the planning stage, three main requirements are sought, namely the strategy, budget and schedule needed to overcome the problem raised from corrosion of reinforcement. This is seen as an important part for an effective management program as feasibility studies are normally conducted to determine the serviceability of the structure after treatment.

Phase 2 of the program involves physical assessment and actual remediation. Inspections for severity of corrosion are conducted in this phase to determine what strategy or methods are most suitable to be applied. Development of corrosion control strategy would present more option to the management program. Remedial work would be carried out once the proper strategy has been recognized.

Phase 3 of the program mainly deals with future monitoring of the repaired structure. Currently and historically, most of the corrosion control programs are driven by response to incident or urgent need, rather than systematically identifying and managing the existing resources. This can be overcome by implementing internal or external monitoring system using current technology practiced in oil and gas industries

Intelligent Speed Adaptation

Intelligent Speed Adaptation (ISA), also known as Intelligent Speed Assistance, is any system that constantly monitors vehicle speed and the local speed limit on a road and implements an action when the vehicle is detected to be exceeding the speed limit. This can be done through an advisory system, where the driver is warned, or through an intervention system where the driving systems of the vehicle are controlled automatically to reduce the vehicle's speed.

Intelligent speed adaptation uses information about the road on which the vehicle travels to make decisions about what the correct speed should be. This information can be obtained through use of a digital maps incorporating roadway coordinates as well as data on the speed zoning for that roadway at that location, through general speed zoning information for a defined geographical area (e.g., an urban area which has a single defined speed limit), or through feature recognition technology that detects and interprets speed limit signage.

ISA systems are designed to detect and alert a driver when a vehicle has entered a new speed zone, when variable speed zones are in force (e.g., variable speed limits in school zones that apply at certain times of the day and only on certain days), and when temporary speed zones are imposed (such as speed limit changes in adverse weather or during traffic congestion, at accident scenes, or near roadworks ). Many ISA systems will also provide information about locations where hazards may occur (e.g., in high pedestrian movement areas, railway level crossings or railroad grade crossings, schools, hospitals, etc.) or where enforcement actions is indicated (e.g., speed camera and red light camera locations). The purpose of ISA is to assist the driver in keeping to the lawful speed limit at all times, particularly as they pass through different speed ‘zones'. This is particularly useful when drivers are in unfamiliar areas or when they pass through areas where variable speed limits are used.

Types of ISA (Active/ Passive)

The two types of ISA systems, passive and active, differ in that passive systems simply warn the driver of the vehicle travelling at a speed in excess of the speed limit, while active systems intervene and automatically correct the vehicle's speed to conform with the speed limit. Passive systems are generally driver advisory systems: They alert the driver to the fact that they are speeding, provide information as to the speed limit, and allow the driver to make a choice on what action should be taken. These systems usually display visual or auditory cues, such as auditory and visual warnings and may include tactile cues such as a vibration of the accelerator pedal. Some passive ISA technology trials have used vehicle modified to provide haptic feedback, wherein the accelerator pedal becomes more resistant to movement (i.e., harder to push down) when the vehicle travels over the speed limit. Active ISA systems actually reduce or limit the vehicle's speed automatically by manipulating the engine and/or braking systems. Most active ISA systems provide an override system so that the driver can disable the ISA, if necessary, on a temporary basis.

An often unrecognised feature of both active and passive ISA systems is that they can serve as on-board vehicle data recorders, retaining information about vehicle location and performance for later checking and fleet management purposes.

Stress Ribbon Bridge

A Stress Ribbon Bridge is a tension structure, similar in many ways to a simple suspension bridge. The stress ribbon design is rare. Few people including bridge engineers are familiar with this form and fewer than 50 have been built worldwide. The suspension cables are embedded in the deck which follows a catenary arc between supports. Unlike the simple span the ribbon is stressed in compression which adds to the stiffness of the structure. Such bridges are typically made from concrete reinforced by steel tensioning cables. They are used mainly for pedestrian and cycling traffic. Stress ribbon bridges are very economical, aesthetic and almost maintenance free structure. They require minimal quantity of materials. At present studies, on combining stress ribbon bridges with cables or arches, to build most economical stress ribbon bridges.

Form Of A Stress Ribbon Bridge

Superstructure

A typical stress ribbon bridge deck consists of precast concrete planks with bearing tendons to support them during construction and separate prestressing tendons which are tensioned to create the final designed geometric form. The joints between the planks are most often sealed with in-situ concrete before stressing the deck. The prestressing tendons transfer horizontal forces in to the abutments and then to the ground most often using ground anchors. The tendons are encased in ducts which are generally grouted after tensioning in order to lock in the stress and protect them from corrosion. Since the bending in the deck is low, the depth can be minimized and results in reduction in dead load and horizontal forces in abutments.

Substructure

The abutments are designed to transfer the horizontal forces from the deck cables into the ground via ground anchors. Pedestrians, wind and temperature loads can cause large changes in the bending moments in the deck close to the abutments and accordingly crack widths and fatigue in reinforcement must be considered. The ground anchors are normally tensioned in 2 stages, the first step is tensioned before the deck is erected and the rest, after the deck is complete. If stressed in one stage only, there will be a large out of balance force to be resisted by the abutments in the temporary case. The soil pressure, overturning and sliding has to be checked for construction as well as permanent condition.

Ground Conditions

The ideal ground condition for resisting large horizontal forces from the ribbon is a rock base. This occurs rarely but suitable foundations can be devised even if competent soils are only found at some depth below the abutments. In some cases where soil conditions do not permit the use of anchors, piles can also be used. Horizontal deformations can be significant and are considered in the design. It is also possible to use a combination of anchors and drilled shafts. Battered micropiling is another alternative which can resist the load from the ribbon because of its compression and tension capacity.

Blue Brain

Blue brain ” –The name of the world's first virtual brain. That means a machine that can function as human brain. Today scientists are in research to create an artificial brain that can think, response, take decision, and keep anything in memory. The main aim is to upload human brain into machine. So that man can think, take decision without any effort. After the death of the body, the virtual brain will act as the man .So, even after the death of a person we will not loose the knowledge, intelligence, personalities, feelings and memories of that man that can be used for the development of the human society.

No one has ever understood the complexity of human brain. It is complex than any circuitry in the world. So, question may arise “Is it really possible to create a human brain?” The answer is “Yes”. Because what ever man has created today always he has followed the nature. When man does not have a device called computer, it was a big question for all .But today it is possible due to the technology. Technology is growing faster than every thing. IBM is now in research to create a virtual brain. It is called “Blue brain “.If possible, this would be the first virtual brain of the world.

How it is possible?

First, it is helpful to describe the basic manners in which a person may be uploaded into a computer. Raymond Kurzweil recently provided an interesting paper on this topic. In it, he describes both invasive and noninvasive techniques. The most promising is the use of very small robots, or nanobots. These robots will be small enough to travel throughout our circulatory

systems. Traveling into the spine and brain, they will be able to monitor the activity and structure of our central nervous system. They will be able to provide an interface with computers that is as close as our mind can be while we still reside in our biological form. Nanobots could also carefully scan the structure of our brain, providing a complete readout of the connections between each neuron. They would also record the current state of the brain. This information , when entered into a computer, could then continue to function as us. All that is required is a computer with large enough storage space and processing power. Is the pattern and state of neuron connections in our brain truly all that makes up our conscious selves? Many people believe firmly those we posses a soul, while some very technical people believe that quantum forces contribute to our awareness. But we have to now think technically. Note, however, that we need not know how the brain actually functions, to transfer it to a computer. We need only know the media and contents. The actual mystery of how we achieved consciousness in the first place, or how we maintain it, is a separate discussion.

Uploading human brain:

The uploading is possible by the use of small robots known as the Nanobots . These robots are small enough to travel through out our circulatory system. Traveling into the spine and brain, they will be able to monitor the activity and structure of our central nervous system. They will be able to provide an interface with computers that is as close as our mind can be while we still reside in our biological form. Nanobots could also carefully scan the structure of our brain, providing a complete readout of the connections. This information, when entered into a computer, could then continue to function as us. Thus the data stored in the entire brain will be uploaded into the computer.

Submerged Floating Tunnels

The Submerged Floating Tunnel concept was first conceived at the beginning of the century, but no actual project was undertaken until recently. As the needs of society for regional growth and the protection of the environment have assumed increased importance, in this wider context the submerged floating tunnel offers new opportunities. The submerged floating tunnel is an innovative concept for crossing waterways, utilizing the law of buoyancy to support the structure at a moderate and convenient depth . The Submerged floating Tunnel is a tube like structure made of Steel and Concrete utilizing the law of buoyancy .It supported on columns or held in place by tethers attached to the sea floor or by pontoons floating on the surface. The Submerged floating tunnel utilizes lakes and waterways to carry traffic under water and on to the other side, where it can be conveniently linked to the rural network or to the underground infrastructure of modern cities

Basic Principle Of SFT

SFT is a buoyant structure which moves in water. The relation between buoyancy and self weight is very important, since it controls the static behaviour f the tunnel and to some extend, also the response to dynamic forces. Minimum internal dimension often result in a near optimum design. There are two ways in which SFT can be floated. That is positive and negative buoyancy.

Positive buoyancy : In this the SFT is fixed in position by anchoring either by means of tension legs to the bottom or by means of pontoons on the surface. Here SFT is mainly 30 metres below the water surface.

Negative buoyancy : Here the foundations would be piers or columns to the sea or lake. This method is limited to 100 meters water depth

SFT is subjected to all environmental actions typical in the water environment: wave ,current , vibration of water level, earthquake, corrosion, ice and marine growth. It should be designed to with stand all actions, operational and accidental loads, with enough strength and stiffness. Transverse stiffness is provided by bottom anchoring.

Competitive Features Of SFT

Invisible

Crossing waterways, whether being from main land to islands in the sea or maybe more important crossing an inland lake, perhaps the one we are at now will in many cases meet protests both from tourist interests and also from the public in general. Lakes of special beauty or perhaps historical value should be preserved for the future, the crossing of such areas and lakes with SFT may make this possible. An illustration of this may be seen in Fig. 3.1

Length only from shore to shore

The actual SFT structure is only as long as the distance between the shores. If desired the SFT may be connected directly to tunnels and then be completely out of sight for any desired distance.

Hazardous Waste Managment

A hazardous waste is any waste or combination of wastes that poses a substantial danger, now or in the future, to human, plant or animal life and which therefore cannot be handled or disposed of without special precautions. The Hazards and Disasters can be classified into four categories viz., Natural events, Technological events, Man-made events and Region-wise events. The adverse impacts caused due to the indiscriminate disposal of Hazardous Wastes (HWs) come under the category of Environmental Disasters. For example, in 1982, 2242 residents are evacuated after dioxin is found in soil in Missouri, U.S.A. In 1996-97, 265354 tonnes of soil and other dioxin-contaminated material from Times Beach (Missouri, U.S.A) and 26 other sites in eastern Missouri had been incinerated. Release of Methyl Isocyanate (MIC) gas in Bhopal (1984) caused a severe disaster in India. So there is a growing concern all over the world for the safe disposal of hazardous waste generated from anthropogenic sources.

Steps involved in hazardous waste management

Identification of Hazardous Waste Generation: Identifying the HW generating industries is the first step. The HWs are classified under 18 categories and this information may be used to screen the wastes generated and classifying them as HWs. However there are few observations that- there is a probability of occurrence of wastes in more than one category; and this classification system does not give any information to understand the toxic characteristics of HW. Few suggestions are also given to improve the classification system. The data available with the State Industrial Development Corporation (IDC), District Industries Centre (DIC), State Pollution Control Boards etc. may be utilized to identify the industries with a potential for HW generation.

Data Collection: After identifying the HW generating sources, the inventory of the data pertaining to HW generation can be developed by conducting surveys through specially prepared questionnaires to each of the identified sources. This should be followed by field visits for data verification. It is essential that, the data that is obtained from the above options is verified from secondary data (either published data or available for another industry producing similar products).

Waste Characterization: The HW that is generated from the study region should be characterized. For this purpose, it is advisable that the samples may be collected from the waste generation source and analyzed in the laboratory. Literature data may be used in the absence of primary data.

Quantification of Hazardous Wastes: The HWs ar · e quantified based on their individual characteristics. The several options of compatibility of wastes with different characteristics should be studied and segregated. The quantity of HWs will be expressed in terms of each category for disposal (e.g. Recyclable, Incinerable, or Disposable etc). The wastes that are recyclable are used/waste oil, lead wastes, zinc wastes.

Identification of sites for disposal: After quantifying the HW, and assessing the probable area requirements for its treatment, storage and disposal, the sites are to be identified. For this purpose, toposheets and/or remote sensing images of the study region may be used. The sites are to be physically verified in the field and to draw observations pertaining to the four different types of attributes available for ranking the sites. The site with a minimum score out of the available sites for ranking should be chosen as the site for establishing TSDF.

Prestressed Concrete

Prestressed concrete is a method for overcoming the concrete's natural weakness in tension. It can be used to produce beams, floors or bridges with a longer span than is practical with ordinary reinforced concrete. Prestressing tendons (generally of high tensile steel cable or rods) are used to provide a clamping load which produces a compressive stress that offsets the tensile stress that the concrete compression member would otherwise experience due to a bending load. Traditional reinforced concrete is based on the use of steel reinforcement bars, rebars, inside poured concrete. Prestressing can be accomplished in three ways: pre-tensioned concrete, and bonded or unbounded post-tensioned concrete.

Pre-tensioned concrete

Pre-tensioned concrete is cast around already tensioned tendons. This method produces a good bond between the tendon and concrete, which both protects the tendon from corrosion and allows for direct transfer of tension. The cured concrete adheres and bonds to the bars and when the tension is released it is transferred to the concrete as compression by static friction. However, it requires stout anchoring points between which the tendon is to be stretched and the tendons are usually in a straight line. Thus, most pretension concrete elements are prefabricated in a factory and must be transported to the construction site, which limits their size. Pretensioned elements may be balcony elements, lintels, floor slabs, beams or foundation piles. An innovative bridge construction method using pre-stressing is described in Stressed Ribbon Bridge.

Bonded post-tensioned concrete

Bonded post-tensioned concrete is the descriptive term for a method of applying compression after pouring concrete and the curing process. The concrete is cast around plastic, steel or aluminum curved duct, to follow the area where otherwise tension would occur in the concrete element. A set of tendons are fished through the duct and the concrete is poured. Once the concrete has hardened, the tendons are tensioned by hydraulic jacks that react against the concrete member itself. When the tendons have stretched sufficiently, according to the design specifications they are wedged in position and maintain tension after the jacks are removed, transferring pressure to the concrete. The duct is then grouted to protect the tendons from corrosion. This method is commonly used to create monolithic slabs for house construction in locations where expansive soils (such as adobe clay) create problems for the typical perimeter foundation. All stresses from seasonal expansion and contraction of the underlying soil are taken into the entire tensioned slab, which supports the building without significant flexure. Post-stressing is also used in the construction of various bridges; both after concrete is cured after support by false work and by the assembly of prefabricated sections, as in the segmental bridge.

The advantages of this system over unbounded post-tensioning are:
1. Large reduction in traditional reinforcement requirements as tendons cannot distress in accidents.
2. Tendons can be easily 'weaved' allowing a more efficient design approach.
3. Higher ultimate strength due to bond generated between the strand and concrete.
4. No long term issues with maintaining the integrity of the anchor/dead end.

Unbounded post-tensioned concrete

Unbounded post-tensioned concrete differs from bonded post-tensioning by providing each individual cable permanent freedom of movement relative to the concrete. To achieve this, each individual tendon is coated with grease (generally lithium based) and covered by a plastic sheathing formed in an extrusion process. The transfer of tension to the concrete is achieved by the steel cable acting against steel anchors embedded in the perimeter of the slab. The main disadvantage over bonded post-tensioning is the fact that a cable can distress itself and burst out of the slab if damaged

Concrete Admixtures

Admixtures are ingredients other than water, aggregates, hydraulic cement, and fibers that are added to the concrete batch immediately before or during mixing, in nominal quantities. A proper use of admixtures offers certain beneficial effects to concrete, including improved quality, acceleration or retardation of setting time, enhanced frost and sulphate resistance, control of strength development, improved workability, and enhanced finishability. Admixtures vary widely in chemical composition, and many perform more than one function. Two basic types of admixtures are available: chemical and mineral. All admixtures to be used in concrete construction should meet specifications; tests
should be made to evaluate how the admixture will affect the properties of the concrete to be made with the specified job materials, under the anticipated ambient conditions, and by the anticipated construction procedures.

Materials used as admixtures included milk and lard by the Romans; eggs during the middle ages in Europe; polished glutinous rice paste, lacquer, tung oil, blackstrap molasses, and extracts from elm soaked in water and boiled bananas by the Chinese; and in Mesoamerica and Peru, cactus juice and latex from rubber plants. The Mayans also
used bark extracts and other substances as set retarders to keep stucco workable for a long period of time.

AIR ENTRAINMENT

It is the intentional creation of tiny air bubbles in concrete. The bubbles are introduced into the concrete by the addition to the mix of an air-entraining agent, a surfactant. The air bubbles are created during mixing of the plastic concrete, and most of them survive to be part of the hardened concrete. The primary purpose of air entrainment is to increase the durability of the hardened concrete, especially in climates subject to freeze-thaw; the secondary purpose is to increase workability of the concrete while in a plastic state. A water: cement ratio (w/c) of approximately 0.25 is required for all the cement particles to hydrate. Water beyond that is surplus and is used to make the plastic concrete more workable or flowable. Most concrete has a w/c of 0.45 to 0.60, which means there is substantial excess water that will not react with cement. Eventually 5 the excess water evaporates, leaving little pores in its place. Environmental water can later fill these voids. During freeze-thaw cycles, the water occupying those pores expands and creates stresses, which lead to tiny cracks. These cracks allow more water into the concrete and the cracks enlarge. Eventually the concrete breaks off. The failure of RCC is most often due to this cycle, which is accelerated by moisture reaching the reinforcing steel. Steel expands when it rusts, and these forces create even more cracks, letting in more water. These air bubbles that are created improve the resistance of the concrete structure against Freeze and Thaw cycles.

WATER REDUCERS or PLASTICIZERS

Water-reducers generally reduce the required water content of a concrete mixture for a given slump. These admixtures disperse the cement particles in concrete and make more efficient use of cement. This increases strength or allows the cement content to be reduced while maintaining the same strength. The basic role of water reducers is to deflocculate the cement particles agglomerated together and release the water tied up in these agglomerations, producing more fluid paste at lower water contents. Water-reducers are used to increase slump of concrete without adding water and are useful for pumping concrete and in hot weather to offset the increased water demand. Some water - reducers may aggravate the rate of slump loss with time. Water-reducing admixtures are used to improve the quality of concrete and to obtain specified strength at lower cement content. They also improve the properties of concrete containing marginal- or low-quality aggregates and help in placing concrete under difficult conditions. Water reducers have been used primarily in bridge decks, low-slump concrete overlays, and patching concrete.

RETARDERS or SET-RETARDERS

They are chemicals that delay the initial setting of concrete by an hour or more. Retarders are often used in hot weather to counter the rapid setting caused by high temperatures. Most retarders also function as water reducers. Retarders should meet the requirements for Type B or D in ASTM C 494.

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