WALL STRUCTURES

Post 682 –by Gautam Shah

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Wall structures have been prime structure for community purposes like, flood protection, irrigation, defense, terrain contouring and against erosion of land. These, perhaps preceded the walls erected for construction of dwellings. The builders from ancient times, were innately aware of the difference between a wall carrying side thrusts and bearing vertical loads. And accordingly the forms and techniques of constructions were different. The walls carrying side thrusts followed the natural angle of repose (the steepest angles at which a sloping surface is formed of loose material remains stable). The walls carrying vertical loads were designed with concern for lateral stability, and to a lesser extent worry about load bearing capacity.

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The idea of a column, as a ‘zero-sized’ wall, (like the Stonehenge) and of pillars (obelisks) may have come from tree trunks. Wood scaffolds were used for painting tall cave walls and ceilings. A series of props or poles, were used as piles or spikes for quicker formation of linear structures, such as in under-water constructions, floods, wet soils, or support against sand like loose soils.

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Earthen Wall structures for embankments or dams, for water flow regulation, storage, prevention of land erosion, against flooding, access-way (road) construction, for irrigation or navigation channels were constructed by combination of deposition or cutting-dressing. But the skill rested in exploiting the existing contours of the lands. Such structures were large and affected the entire community. For participation of large number of people, clear perception of the project and its benefit was necessary. It is apparent that such projects were executed during certain season. These were continuing efforts as added upon and improvised by several generations. Such lasting efforts can occur in societies that are politically and socially stable.

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Other walls were erected in the form of city-town walls to protect the community, and monumental structures related to burial facilities. These walls due to their extent gave impression of monumentality, and were gravity-stable and invincible forms against the invaders or marauders. Walls defining passageways are for land mass retention and ceremonial demarcation of walkways. Town walls and monumental walls, both were not ‘load-bearing’ structures. Both also related to access by large number of people, often in processions. The inevitable entry point was well marked in scale and position-location.

16 Passage tomb of La Hougue Bie by © Copyright Bob Embleton and licensed for reuse under this Creative Commons Licence.

Protective walls were often constructed as tall fences. These were made insurmountable by various means like an enhancement of height-width factors. Width was increased by forming a ditch on the face of the wall, and height was added by constructing the wall over a natural steep edge of terrain. City walls in some areas were constructed of tree trunks or wood lattices.

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Palisade in Celtic village Wikipedia image by Zureks

A palisade, was a defensive fence (also called a stake-wall or paling) formed around the military camps by Greeks and Romans. It is formed of wood stakes or tree trunks placed in a line. A groyne is a similar, but low height wall structure, a hydraulic entity for interrupting the free flow of water and restricts the movement of soil-sediments from coastal area.

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A levee, dike, dyke, ditch, embankment, flood-bank or stop-bank, are naturally occurring long ridges or artificially constructed walls to regulate water. These are usually of stone and earth, and follow the course of a river. Levees and other structure require constant care by organized society. Some of the earliest levees were constructed by the Indus Valley Civilization (2600 BC), Egyptians to manage the floods of river Nile, in Mesopotamia and China. The word Levee or F. Lever, literally means ‘to raise’.

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The Greek geographer Pytheas noted in 325 BC, that ‘more people died in the struggle against water than in the struggle against men’.

The word Dyke (dijk) indicates, both trench and bank for water management. The word Ditch derives from dic, dick or dig, meaning to digging a trench and raise the banks with the excavated soil. Such earthworks acted as horizontal walling to deepen water channels, enhance the flow-rate and water carrying capacity. The water channel shaping by the side walling structures provided reliable lanes for waterways. These wall structures were formed to reduce the erosion by water flows, waves and winds.

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The first dikes and water control structures were built and maintained by those directly benefiting from them, mostly farmers. As the structures got more extensive and complex councils were formed from people with a common interest in the control of water levels on their land and so the first water boards began to emerge. These often controlled only a small area, a single polder or dike. Later they merged or an overall organization was formed when different water boards had conflicting interests. The original water boards differed much from each other in the organization, power, and area that they managed. The differences were often regional and were dictated by differing circumstances, whether they had to defend a sea dike against a storm surge or keep the water level in a polder within bounds. In the middle of the 20th century there were about 2,700 water control boards. After many mergers, there are currently 27 water boards left. Water boards hold separate elections, levy taxes, and function independently from other government bodies. -Flood control in the Netherlands Wikipedia

Mycenaean city walls

City walls are elaborate ‘fencing structures built from stronger materials to fortify a territory. The fort walls were symbols of power, so the scale was grandiose. These walls were planned at most select location, adding upon whatever natural defence features were available. Appropriateness of the site also rested on logistics of supply, of which food-fodder and drinking water, even during seizure condition, was very important. Forts housed a populated community and to sustain it, also included structures for defense preparedness and for offense capacity like ditches, gates, embankments, watchtowers, crenelation, etc.

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A moat is a ditch or long pit around a settlement with or without a fence or fortification. Moats were created by reforming the existing terrain features, or dug as a new one. Fortified structures, like castles were once sited over difficult terrains, where some natural features such as hills, elevated lands or rocky landscapes were available for some protection. Moats were additional defence provisions, formed at vulnerable spots. The difficult terrains, however, make it difficult to reform existing terrain, or excavate a new trench. Digging a moat was not only labourious, but the management of the excavated material equally difficult. The excavated stuff was used to back support the fort walls, or raise the level of internal grounds. Moats were formed along with construction of fort walls.

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Some of the earliest defensive walls were linear formations and not any surrounding or enveloping forts. These were long barrier walls with open ends or terminating into hillock or large water body. These linear walls marked a territorial edge or boundary of the kingdom. Such edge walls had to be very extensive to be effective.

Sumerian King Shulgi of Ur, 2038 BC., built a wall that was 250 Kms long, between the Tigris and Euphrates rivers, to keep the invading Amorites out of Sumerian lands. Great Wall of Gorgan (restored and renovated by the Sasanian Persians in the 5th or 6th C) was 195 Kms long, and included more than thirty forts along its length. Great Wall of China was built as several small independent units, possibly first at vulnerable points, which were ultimately joined together during the Ming Era. It was as a freestanding regional scale defensive structure. Similarly the Anastasian wall (the Long Walls of Thrace) of the Byzantine Empire (469 C) located in modern Turkey was also not anchored at either end to any terminus. All such walls proved to be ineffectual as enemy army marched around the ends. The most known wall structure, Hadrian’s wall of Britain was built by Roman Emperor Hadrian (122 AD) to prevent frequent incursions.

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BMR and BODY TEMPERATURE

Post 680 –by Gautam Shah

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37th Annual Yokota Striders Frostbite Race

BMR: Basal Metabolic Rate is the amount of energy (metabolism-calories) per unit of time that a person needs to keep the body functioning, at rest. The ‘rest’ or body sustenance functions include breathing, blood circulation, controlling body temperature, cell growth, brain and nerve. The basal metabolic rate accounts for about 60 to 75% of the daily calorie expenditure by individuals. About 20% of energy expenditure comes from physical activities and another 10% from digestion of food. It is influenced by several factors, such as the age, gender, degree of acclimatization, posture and state of health. The primary organ responsible for BMR regulating metabolisms is the hypothalamus.

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Our body functions as a thermo equilibrium system, with upper limits of bearing is 52° C, and lower limits of 3° C. A body may endure or adopt to certain abnormal conditions for a period of time, but there may occur side effects. The side effects may be realized in a different form and at a different time. In certain acute work conditions like mines, metal smelting plants, textile plants, cold storage, the levels of efficiency or productivity depend on the endurance level and adaptability of the body.

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The human body has many minor variations, but an average temperature of 37° C. Body temperature is highest in the evening and lowest in the morning (+or- range of 1° C.) energy expenditure of the body is different for endothermic animals and fish or reptiles. In reptiles and amphibia heat regulation mechanisms is absent. Their body temperature rises or falls with the atmospheric temperature. Hence they are called cold-blooded animals. In abnormal temperature conditions they regulate the body temperature by suitable habitat like burrowing and hibernation.

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Infants have a very imperfect mechanism for regulation of body temperature. A fit of crying may elevate and a cold wash may lower the body temperature. Aged persons have a low metabolism, and so maintain a lower body temperature. It takes much longer for an aged person to gain or dissipate body heat. Female body temperature is slightly lower than male. High protein foods increase the body temperature. The act ingestion and food digestion and exercise raises the body temperature. Atmospheric conditions like, temperature, humidity and movement of air, affect the efficiency of heat exchange from the body, and so the body temperature.

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There are three types of heat generating processes in the human body. Conversion of food matter into useful energy, Muscular activities, and Certain infections and dysfunctions within the body, elevates or lower the body temperature by extra ordinary rate. Many physical, chemical and bacterial agents disturb the heat regulation mechanism and cause fever. These may be due to increased heat production or reduced heat loss, or both.

Africa School Life Joy Happy Students Literacy

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THE PALEOLITHIC WALL PAINTING

Post 677–by Gautam Shah

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The wall paintings (upper palaeolithic eras) began as a medium of expression -a ‘story’ telling exploit. It was not a decorative art for a place, but a ceremonial craft in a space. The paintings were in deep caves as well as open sites. Bhimbetka, India, sites shows human occupation for more than 100,000 years, but earliest paintings on the cave walls here date back just 30,000 years ago.

Bison Cave of Altamira

Upper Palaeolithic period began roughly around 40,000/60000 years ago and lasted through the Pleistocene ice age, which is believed to have occurred near 8,000 B.C. This period was marked by the rise of Homo sapiens and their ever-developing ability to create tools and weapons.

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The cave sites were difficult to access but were perhaps special and visited by several generations. The caves were deep and dark and artists worked with lamps and torch lights. The paintings were made on walls, ceilings and even floors. Many of the locations and surfaces were acutely irregular. Artists had to work in squatting lying position or use elaborate scaffolding to reach the heights. The scale of the job was stupendous. Deep cave paintings have survived, whereas open location paintings have generally been destroyed.

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At Bernifal in the Dordogne, the mammoths are painted 20 feet up. Some of the bulls at Lascaux are more than 20 feet long. The big cave vault at Lascaux, known as the Picture Gallery, is more than 100 feet long and 35 feet wide.

Lascaux_painting image by Prof saxx

The cave art consists of simple impromptu works as well as grand executions. The first types were perhaps executed by amateurs or apprentices, and the second by masters. To sustain projects of such scale, the master artists were helped by a retinue of assistants and the community. The assistants helped in erecting scaffolding, preparing the surface to be painted, mixing colours, devising brushes and other colour application tools, feeding animal fats to lighting torches, provisioning food and water.

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The cave artists have shown very high degree of professionalism. The compositions, understanding of the animals’ anatomical details, animals’ form, dynamism and movement, all represent a keen sense of observation, experience and discipline.

The limited choice of colours has been overcome by the masterly expression of form. There is consistent economy of line. The textural and tonal qualities do not represent the light and shade, yet suggest the depth through colour differentiation (recognizing the ‘grey tone value’). At places existing substrate textures have been exploited. The scale and distribution of objects within a composition do not follow a visual proportion system, yet prioritize the elements of the story.

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Wall painting began as a line drawing. Lines were frequently scrapped through a sharp edged tool. The etched lines perhaps helped in retaining the charcoal or soft stones rubbings. Such art works, as the primary responses were impressed on whatever interior or exterior surfaces that were available. However, it was realized that more permanent work can only be created in a protected space. The caves space and its environment stimulated a spiritual experience for the portrayal. The spaces must have been favoured by several generations, as some of the paintings have been modified repeatedly over thousands of years. The earliest works are refined compared to later works or modifications.

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There is nothing to suggest that the art was a setting of a ceremony. There is no depiction of a sacrifice, or a master of ceremonies like a priest, sorcerer or a witch-doctor. The paintings also have no images of the surrounding terrain or the vegetation of the time.

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The palaeolithic wall art consists of three main categories of subjects: animals, humans and signs (abstract or unexplained). The animal figures are the most detailed and naturalistic representations, but drawings of humans are rare and perfunctory. ‘In the case of Chauvet, predatory or dangerous animals dominate, while in Lascaux the main representations are of large herbivorous mammals’. At caves across various geographic locations the animals include: woolly rhinoceros, lions, bison, horses, aurochs, bears, reindeer, wisent, and giant deer and hyenas. At places species which were then extinct (as per the time dating technology), are also painted. Some of the most common species such as the reindeer do not find any representation, though bones have been found in the cave. The wall art also includes prints of spray painted hands, with abstract interconnecting lines.

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The abstract signs are said to be representing the perception of night skies, of stars etc. Some forms of visual effects of movement or vibrancy (experienced in limited illumination) were perhaps included by use of florescent dyes, and slightly shifted images.

MATERIALS and TECHNIQUES

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Wall art of upper Palaeolithic age in the early phase did not have any surface preparation except scrubbing off the loose particles and dust. Selected surfaces were away from flowing or leaching water. Early phase drawings were done in line work with charcoal, but compared to this the carbon black, a deposit over an animal fat burning lamp had better binding and colour saturation. Lines were also scratched or etched by a sharp tool and done over with a black colour. Scratching the surface also ensured better colour retention. Later renderings (filling up the colour) with red ochre (Iron oxide from Haematite) and black was done. In the later phase (25000/20000 BC) other colours such as yellow and brown were added to the palette.

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In the initial phase dry colours were rubbed over the surface. In the later phase colours were ground with water and additives like blood, urine, eggs and animal fats. The additives improved the bonding, increased the viscosity (to prevent run off the surface) and reduced the drying time (allowing application and rendering effects). Learning also included: how to prepare intermediate shades (orange and browns), prevent algae like growth, avoid colours that fade over an age and moisture bleeding of colours and additives. Colours were mixed Calcium containing water or nodules to improve fixing.

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The colours were ground by rubbing them over a rough surface, and also through pestles and mortars. At Lascaux, some 158 different mineral fragments were found. Shells of barnacles and human skulls were used as containers for ground pigment pastes. Colour was applied by brushes, twigs and fingers. Colours were also put on by spraying through mouth and blow pipes made from bird bones, and by daubing with hands, fibrous pads and soft skins. Colours were sprayed over hands as the stencils to perhaps mark the participation or visitation.

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SHADING DEVICES for BUILDINGS

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Post 670 by Gautam Shah

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Openings need additional shading systems primarily because these are thin and more translucent in comparison to any other structural barrier systems, like walls, floors or roofs. Additional shading systems are preferred because the needs are for small period of time, part of a season, occasion or location. The needs for a shading device are people, culture or locality specific. The openings are used for outward and inward view, illumination, breeze and air change. And shading devices achieve needs by blockage, filtration, reflection, redirection or delays.

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Opening systems like Gates, Doors and Windows have three distinct zones: The exterior zone deals with environmental aspects that are spatial extensive, directional, temporal and seasonal, The interim section constitutes the body of the opening, and so its depth is the operative element. The interior segment is in the personal domain of the owner-user, which makes Interior shading devices easy to install, manouevre, change, with variable yet very precise control over the functions. Interiors shading devices are also visible from outside and so some conflicts of approach to design are inevitable. In most likely scenarios the architect is a different person than the Interior designer, who may or may not confirm to the theme of architecture.

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Shading Devices with openings are of many different types. Different types of shading devices improve each other’s functions, often duplicating it. There is a strong demand to rationalize the system with fewer elements, by way of integration, removal of duplication and redundancy. Shading devices offer micro tuning of the environment, catering to local requirements, provide occasional variations and satisfy the urge for personalization.

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● External shading devices are architectural provisions, with varying levels of integration. There is an overwhelming regimen of the building style, location, orientation and shape-form. The provisions are so confirmatory that user is not allowed to make any changes. The provisions, though occur as fixed devices and as manipulable systems, no spatial relocation is allowed.

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External shading devices are of longer lasting materials as these have to bear the elements of environment like Sun, rain, heavy storms, snow, atmospheric pollution. These are termed architectonic element due to the match with architectural language.

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External shading devices are very effective, as they intervene before the radiation, rain, wind etc. enter into a building shell. Such devices de-rigueur have universal design for all faces and floors, but are affective differently at different times of the day or season.

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● Interim shading devices have thickness as the key factor, and are usually thin. Interim systems could have partial spread or have options of folding, collapsing or demounting. These are frugal and likely to be a single purpose entity. Interim shading systems are often spatial provisions of vacuum or gas filled cavities.

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● Internal shading Devices occur in a user domain and so are preferred for the ease of choice, installation, change and manipulation. These provide variable yet very exact control over privacy. The internal shading devices are housed in a protected environment so can be delicate, lighter in weight and occupy a very small thickness.

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Internal shading devices are multi layered to serve diverse purposes, and offer several choices of spread or placement. The space between different layers is intentional, to work as a metaphysical barrier. Internal systems also serve purposes beyond the shading, like sound and thermal insulation of the interior space. These also provide a tactile (soft) surface, colour and textural effect in the interior space. Interim shading devices filter and diffuse the light in inward and outward directions.

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Internal shading devices are predominantly of soft materials such as fabrics, films, sheets, flexible materials like mats, nets, tapestries, or stiffer materials such as reeds, wood slats, etc. Thin and pliable materials allow the assembly to collapse, gather or roll up. Glazing materials offer largest variety of surface treatments, by way of manufactured constitution, integrated and applique surface treatments. Glass surface treatments now include application of films, texturizing, metalizing, micro (nano or molecular level) engraving, enamelling and colouring.

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Shading devices such as Venetian blinds or vertical louvers are not very effective on the internal face of the opening, as the solar gain has already been admitted into the interior space. But interior shading devices offer glare control, and visual comfort. An internal shading device reflects back part of the radiation, but latent heat remains within the interior space.

Shading Devices are single or multi layer systems, acting as a composite or assembly of individual skins. The layers have prearranged sequence, so access to an inner layer becomes difficult. Some can be collapsed or removed. Layers form a planer element with some materials plus cavities as the substantive body.

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Additive or mounting systems are used as optional or occasional facility like storm shutters. Collapsible or folding systems require a volumetric space for parking or resting, which reduces the net area of opening. Pseudo or pretentious shading devices are in the form of furniture elements, furnishings, panelling, partitions and other architectural devices.

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Thermal management by shading devices: These are designed to take optimum advantage of seasonal angles of a solar incidence. The solar gain occurs primarily in reference to the plane of the window, so an alternate method could be to have a variable plane of the window, but that may not be an appropriate architectural style. However, external shading devices keep the glazing surface in shade to cut off the direct solar radiation.

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Vision management through shading devices: Shading devices as subsystems divide the view out or inwards by framing, masking, modelling. The visual scape is altered through the sill and lintel level and shape, pattern configurations, quality of glazing etc.

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Safety security with shading devices: External shading elements maintain or reduce the size of opening, and so become integrated latticed barriers for safety and security against height related hazards.

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WORK PROCESSES -simplified overview

Post 657 -by Gautam Shah

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Workshops till middle age were craftspeople oriented. A crafts person would occupy a place surrounded by tools and equipments and carry out the ‘Lot’ of work. After that another person took over that lot. For heavy duty jobs mechanical power drives were superior, but one had to shift around to use them. Mechanical devices like gears, leather belt transmission and offered greater productivity. Some degree of task assignment offered standardized products on a massive scale. The power shaft forced organization of workshops on linearity. The line production methods promoted productivity through time management and sequencing of task procedures. In many instances tasks began to be assimilated and handled simultaneously by many crafts-persons in a single time slot.

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power shaft pulley beltsDuring the early part of the 20th C. machines became adjuncts to assembly-line production systems and multi tasking. For this machine became a device to handle a variety of tools, often simultaneously. The machines were operating at a faster speed requiring equally fast control system.

595px-Machine_shop_in_the_Government_Printing_OfficeMechanical power transmission systems were concurrent systems for the entire workshop, but this impediment was removed with the electric power. Electrical power offered local control through an electric motor through horse power rating, speed variation through voltage control and gears, and operational control like start-stop, etc. Independent electric powered machines with faster and multi tasking capabilities, however, were now difficult for human supervision. Control devices were actuators, for process regulation.

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Control devices or systems are of two types: A Feed-forward system has inputs or predicts unusual happening, but would not oversee or govern the actualization of the action. A Feedback system improvises strategy for future actions in many instances oversees actions being taken.

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Feed-forward systems: Jacquard weaving loom uses a feed-forward control as a programmed punched card to weave a pattern, but cannot stop the loom if there is a short feed of thread. Similarly a cutting machine cuts a large sized shape by moving the cutter tracing a small scale pattern through the arm of a pantograph.

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Feedback systems: A wind mill keeps facing the wind with the help of a tail wane. A pressure cooker seals itself with heightened internal pressure of steam. Pressure valves are weight calibrated opening themselves at certain pressure levels only.

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Control devices and systems have led to automation of processes. Automation began in the late 1940s with the development of the mechanical devices for moving and positioning objects on a production line, though observation and manual intervention were necessary. During 1960s digital computers began to offer control systems in three different manners: For supervisory or optimizing control, Direct digital control, and Hierarchy control. In the first instance, for the supervisory control a computer sets parametric levels for optimizing the operations. In the second instance, for the direct-digital control, several devices feed data to a single processor, which then decides a strategy of operation. The advantage here is very fast and objective evaluation of the data. The third system the hierarchy control applies to all the plant-control situations concurrently, often with the actuation of the control mechanisms.

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METAL CLEANING PROCESSES

Post 571by Gautam Shah

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Metals parts need surface treatments and cleaning for conservation, restoration,  decoration, reflectivity (shine), dulling (removal of gloss), better hardness, surface integrity, prevention of corrosion and in preparation for the next treatment. Metal components get both organic and inorganic substances deposited from various lubricating oils, corroding environments and substances, and deposits from hard water etc. Metal surfaces need cleaning for removal of residual products from earlier processing, weathering, depositions during storage and transport and environmental contaminations. A cleaned metal is comparatively more active, and so may need, immediate next treatment, to prevent corrosion and contamination. So metal surfaces often receive simultaneously the processes of cleaning, surface activation and protection.

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Metal surfaces needs to be smoothed, scrubbed or scoured to receive next set of treatments. Cleaning processes are employed to discharge electrical ions from the component. Cleaning processes are designed to serve several purposes, such as cleaning, scoring and protective coating. Cleaning occurs at a raw material stage, product formation stage, in preparation to other finishes, or just prior to a marketable finish. But there are two distinct stages, at manufacturing plant and on-site applications.

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Center-less grinding  Wikipedia image by Wizard191

Alkali cleaning is typically done with caustic soda (NaOH) which removes all polar substances such as fats and oils. The vegetable and animal oils are converted to glycerol and soap, and the petroleum-based oils and grease are emulsified.

Acid cleaning, like alkali removes ionic deposits from the metal surface. Depending on the secondary products like salts determine the quality of acid to be used. Pickling process removes oxides from the surface by a dissolving liquid. For steel, a warm dilute sulphuric acid, and in some cases hydrochloric acid, hot or at normal temperature, is used. However, for some alloy steels nitric acid, is needed. Acid and alkali both processes require post treatment ph. balancing rinse or treatment.

Solvent cleaning: the articles are washed with a petroleum solvent or undergo cleaning (de-greasing) by vapour, in which a solvent such as tri-or tetra chloroethylene is heated in a closed system, and its vapours are condensed on the metal surface.

Emulsion cleaning: the metal parts are immersed in a warm mixture of kerosene, a wetting agent, and an alkaline solution.

Mechanical cleaning use force of air or water jet and sonar waves to remove partially attached particles. The process may include fine particles like sand, silica, metal grit etc. to blast the surface for the same purpose.

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Electrolytic cleaning: the articles are immersed in an alkaline solution and a direct current is passed between them and the other electrode which is usually steel.

Ultrasonic cleaning is used for blind holes or gears packed with soils etc. Small particles embedded in crevices get detached due to ultrasonic waves.

Plasma treatments bombard a surface with electron ions to break the surface level chemical bonds and change the chemical composition of the surface. Plasma treatments may also remove variety of material types such as paints, polymers, glass and ceramics.

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Statue of Perseus Piazza della Signoria Florence After cleaning Image by Jrousso at Wikipedia En

Metal cleaning Tools and Techniques

The metal products are small items like nails, rivets, long rolled sections, drawn items like wires, woven items like lattices, entwined items like ropes and barbed fencing, hollow pipes and tubes, or solid castings. Other products include assemblies like automobile bodies, boxes, cages, machine housings and structures like a truss. Metal components are single or multi-metal items, composites with polymers, ceramics, etc. Art restorers have to deal with metal objects of unknown composition, ageing, and coated with natural or applied substances. Art restorations require reversible processes, so if a treatment is found unviable it can be fully reverted. Metal products in continuous line productions are moved through several sets of electrodes, which, submerged in a cleaning liquid, electrolytically generate hydrogen gas at the steel surface for lifting residues off the material.

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Sand-blasting Wikipedia image by National Institute for occupational safety and health NIOSH USA

Hard substances like metal nodules or slags are removed by abrasion or high pressure air or water jet. Soft materials like soil etc. are removed by brushing. Brushing may be carried out dry or wet and with scrubbing and scourager agents. Brushes with natural hair, synthetic fiber, metal fibres and wires are used. Abrasive materials like A Carborundum, sand grit, metal particles etc. are blasted on the surface to clean up the surface. In some instances like manufacturing of nails, abrasive materials rotated in ball mills with nails, to achieve high polish. Ultrasonic sound waves are also used to remove particles.

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BUILDING as a COMPLEX SYSTEM

Post 508  by Gautam Shah

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A building is a complex system that manifests for a set of Users, within an Environment, and built through many different Components. Users pose a set of demands that are situational and circumstantial. The Environment affects the building, and gets affected by its existence. The Components forming the building have a variable mutual dependency, some of which are rare, but required for assuring the safety and security.

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User-related demands and environmental affectations bear upon the building’s fabric, where components show unequal performance. Some of these components are mutually dependent, and have a state of permanency, but many are detachable and so replaceable and up-gradable. Replacement of components occurs during regular maintenance schedules with identical or upgraded units. Alterations and Renovations are considered opportunities for rejuvenating and upgrading the building system. There is distinct effort to improvise the system by replacing subsystems with new technologies. Compared to these changes, for buildings going through Conservation, all components and sub-systems are sought to be continued, by small repairs or replacing with re-manufactured identical elements.

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Building as complex system is agglomeration of various components and subsystems, where the detachable entities can be replaced. The changes are carried out to replace not only the worn out components, but to add more productive components. Components and subsystems are replaced to endow a new image to the building. The technological up-gradation of subsystems or components occurs in many ways.

PV_external_shading_device_in_zero_energy_building_of_Singapore1 Custom-made components and subsystems are replaced by standard systems. These, makes future servicing and replacement much easier.

2 Newer systems are preferred for their efficiency in terms of energy use, out-put of waste products, compactness, fitment rationale, noise and vibrations.

3 Newer systems are multipurpose, and replace several sub-systems that existed as layers or closely placed elements.

Image Wikipedia – Flickr by Author flickr user rick

4 New components and subsystems have different fitment parameters, and so require customized installation yet the replacements always remain detachable.

5 When a building is completely overhauled, it offers a chance to integrate several stand-alone sub-systems by spatial rearrangement or rescheduling.

6 New subsystems have built-in provisions for remote switching, monitoring and synchronized operations, these allow for networking through master control.

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7 Older sub-systems and components were support structure and location dependent, requiring walls, external facing, services connections, etc. Newer systems have reduced dependence being lighter in weight, compact in size, energy efficiency, requiring no liquid-solid fuels and no waste output.

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