Tuesday, August 3, 2010

my Portfolio !!!!!

T.L.E

"GRAPHICS, SCIENCE AND ARTS"

BOOKBINDING

Bookbinding is, of course, the process of fastening together the multiple pages which make up a given book, and covering the result. Given the changes which have occurred in the past ten or fifteen years, both in structural technique and artistic presentation, the subject is complex and often controversial.

Traditionally, the craft of bookbinding is divided into the areas of forwarding and finishing. Forwarding consists of all the procedures leading up to the decoration of the covers. That is, folding the leaves into pages and gathering into signatures or quires, sewing them together, adding endpapers, attaching boards, and covering. In other words, the binding proper. Finishing is a specialized field involving gold (or blind) tooling, and sometimes inlay and on lay work: the artistic embellishment of the binding.

Note that there is a significant difference between Eastern and Western binding. In the west, the sheets of paper are relatively thick and opaque enough to print on both sides, and when folded, are sewn through the fold. In the east the sheets are much thinner and relatively transparent so they are printed on one side only. The sheets are folded so that the printed side is outermost, and the sewing is done opposite the fold, through the edges of the two loose halves. Books sewn in the Eastern style do not open flat.

SOME HAND BOOKBINDING TERMS

GRAIN DIRECTION (Grain) The direction in which most of the fibers in machine made paper lie. Grain direction should be parallel to the spine of the book.

SIGNATURE (or Section) A number of leaves gathered together, folded, and treated as a single binding unit.

BOOK BLOCK (or text block) A group of signatures which form a book.

SPINE The back or folded edges of a group of signatures, or the part of the cover which protects this area.

ROUNDING AND BACKING - Rounding: The formation of the convex spine.

Backing: The formation of the supporting shoulders.

FORE-EDGE The front edge of the book, opposite the spine

END-PAPER A folded sheet of paper or additional blank signature acting as a protection for the book-block and as an attachment of book block to cover.

HEADBAND (End-band) Thread woven around an inner core to form a protection at the head and tail of the spine of the book; often now cloth wrapped around a core.

BANDS The ridges across the spine of the book; the supports around which the sections are sewn.

COVER The outer protection for the book-block.

JOINT - Inner joint (hinge): the inside hinge of the cover made of the fold of the end-paper or of a strip of paper or leather attached to the end-paper.

Outer joint: the point at which the cover boards pivot as the board opens.

SQUARE The portions of the covers of the book which project beyond the edges of the leaves of the book-block.

HEAD-CAP Covering leather shaped over the headband of the book.

TURN-IN The part of the covering material that is turned over the edges of the boards from the outside to the inside at the head, tail, and fore-edge of the book.

CASE A book cover that is constructed completely before affixing to a book-block.

TIPPING The attachment of a leaf to another by means of a narrow strip of adhesive along one edge; mostly used for maps, pates etc.

Materials Required for bookbinding

Sheets of paper (depending upon the size of the book)
Piece of cardboard
Wallpaper, contact paper, felt or cotton fabric
Paper cutter
A pair of scissors
White glue or wallpaper paste
Needle with a large eye
Twine, carpet thread, crochet thread or quilting thread.

Procedure

For the Book
Determine the size of the book that you require. Fold the sheets midway. If you want a book of 5 1/2″ x 9″ dimensions use sheets of paper having dimensions of 11″ x 18″ as folding them midway will give you pages of the desired size. Each side of a folded sheet of paper will give four pages. Hence divide the number of pages you want to have for your book by 4. Use one sheet extra than the number that you get. This extra sheet will serve as the first and the last page onto which the cover will be pasted.

Place all the sheets on top of each other. Fold them midway. Clip all the four edges to hold the sheets in place. You can also clip the center of the fold. Beginning ½ '' from the top of the fold, start marking for holes at regular intervals. Make holes with the needles and sew the book along the holes.

For the Cover
Cut two cardboard pieces in the shape of the book. These pieces could be the same size or a little larger than the book's dimensions. Place the two pieces on the felt, cloth or the material you are using to cover the cardboard pieces such that there is a gap of 1/8″ to 1/4″ between them. Draw the outline of the cardboard pieces on the material with a pencil. Remove the cardboard pieces. Now cut the material one inch around the entire outside of the pencil mark.

Apply glue to the cardboard pieces and place them along the pencil mark. Apply glue to the one inch of extra material along the border of the cardboard pieces. Fold in the four corners so that the tip of the corners of the material lies on the diagonal of the cardboard piece. Now fold in the material along the sides of the cardboard. Let the cover dry.

Apply glue to the outer sides of the first and the last page of the book. Place the book carefully along the center of the two cardboard pieces and smooth down. Close the book and place some weight over it. Leave it to dry for a few days.

Friday, July 30, 2010

T.L.E 21

"FISHERY ARTS"

Fishery

A fishery (plural: fisheries) is an organized effort by humans to catch fish or other aquatic species, an activity known as fishing. Generally, a fishery exists for the purpose of providing human food, although other aims are possible (such as sport or recreational fishing, or obtaining ornamental fish or fish products such as fish oil. Industrial fisheries are fisheries where the catch is not intended for direct human consumption.

Regardless of purpose, however, the term fishery generally refers to a fishing effort centered on either a particular ecoregion or a particular species or type of fish or aquatic animal, and usually fisheries are differentiated by both criteria. An example would be the salmon fishery of Alaska or the tuna fishery of the Eastern Pacific. Most fisheries are marine, rather than freshwater; most marine fisheries are based near the coast. This is not only because harvesting from relatively shallow waters is easier than in the open ocean, but also because fish are much more abundant near the coastal shelf, due to coastal upwelling and the abundance of nutrients available there.

Fisheries Science

Fisheries science is the academic discipline of managing and understanding fisheries. It draws on the disciplines of biology, ecology, oceanography, and management to attempt to provide an integrated picture of fisheries. It is typically taught in a university setting, and can be the focus of an undergraduate, master's or Ph.D. program. It is currently taught in universities worldwide, including several in the United States.

Important issues and topics in fisheries

Considering the importance of fisheries, and that they depend on a natural resource, it is no surprise that there are many pressing environmental issues surrounding them. These can be classed into issues that involve the availability of fish to be caught, such as overfishing, sustainable fisheries, and fishery management; and issues surrounding the impact of fishing on the environment, such by-catch. These fishery conservation issues are generally considered part of marine conservation, and many of these issues are addressed in fisheries science programs. They are also, however, controversial. There is an apparent and growing disparity between the availability of fish to be caught and humanity’s desire to catch them, a problem that is exacerbated by the rapidly growing worldwide population. As with some other environmental issues, often the people engaged in the activity of fishing – the fishers – and the scientists who study fisheries science, who are often acting as fishery managers, are in conflict with each other, as the dictates of economics mean that fishers have to keep fishing for their livelihood, but the dictates of sustainable science mean that some fisheries must close or reduce to protect the health of the population of the fish themselves. It is starting to be realized, however, that these two camps must work together to ensure fishery health through the 21st century and beyond.

HOW TO CONSTRUCT ARTIFICIAL FISHPOND

STEP 1: Choose a site. A location with lots of plants or a landscaped area would do nicely to give a more natural effect. Remember, the more at home the fishes are, the more they'll be encouraged to breed. Also, make sure that the temperature on that area would be ideal for the fishes.

STEP 2: Calculate how big should your pond be. Since i don't know what types of fishes you will be breeding, i can't do it for you. Yous said that you will breed as much as 100 fishes. I won't go lower than 300 gallons if I were you.

STEP 3: Choose what shape you want. some fish ponds are semi oblique, some rectangular, others circular. the list of shaped is almost endless.

STEP 4: Mark the area you want your pond to be.

STEP 5: Dig the pond, putting barricades on the sides/focal points of the pond to ensure that dirt won't fall back in. The deeper the pond, the better. a deep pond would deter any pests like cats and frogs to enter it.

STEP 6: Cement the floor and the walls. allow them to dry then apply two to three coatings of water proofing painty over it. Allow it to dry then add another layer of cement.

STEP7: If your pond has a wall behind it, decorate the walls with natural stones. this'll act as the primary filter media if you chose to have waterfalls for your pond.

STEP8: Barricade the pond with more concrete. the barricade should be at least 5--8 inches higher than the ground at 0.0 meters. This'll further deter any pests like frogs to enter the pond.

STEP 9: Put a hole somewhere in the higher reaches of the pond (ideally by the wall). this hole will serve as a deterrant against overflowing. water that is too much for the pond will be expelled through this hole

STEP 10: Decorate the pond to replicate your fishes's natural environment. the more at home they feel, the more chances you have of making them breed.

STEP 11: Put water in and let it cycle for 2 to 3 weeks for the growth and maturation of your mini enironemnt.

T.L.E 20

"AGRICULTURAL ARTS"

LIVESTOCK RAISING

Livestock (also cattle) refers to one or more domesticated animals raised in an agricultural setting to produce commodities such as food or fibre, or labor. The term "livestock" as used in this article does not include poultry or farmed fish; however the inclusion of these, especially poultry, within the meaning of "livestock" is common.

Livestock generally are raised for subsistence or for profit. Raising animals (animal husbandry) is an important component of modern agriculture. It has been practised in many cultures since the transition to farming from hunter-gather lifestyles.

The Importance of Livestock

Livestock have an image problem in the developed world. They are blamed for everything from global warming to increasing heart disease. Britain's `mad cow disease' - or bovine spongiform encephalopathy - hasn't helped. Livestock are seen as wasteful, growing fat on grain that people could eat and polluting the environment with their faeces and urine and the gases they give off. But these charges are not true of livestock in the developing world.

True, ruminants produce methane gas, one of the `greenhouse gases' - but methane from ruminants accounts for only some 2.5 percent of the total greenhouse gases. Pastures grown to feed livestock take carbon dioxide out of the atmosphere, tying it up in plant material above and below the ground, just as forests do.

True, eating too many animal products may increase the risk of heart disease - but this is a problem of the developed world, not the developing world. People in developing countries generally eat much less meat than those in the developed world, and the meat they eat is less fatty. Indeed, recent studies from Kenya, Egypt and Mexico show that children who do not get enough meat and milk in their diets may grow up physically and mentally compromised.

Livestock play a vital role in the agricultural and rural economies of the developing world. Not only do they produce food directly, they also provide key inputs to crop agriculture. Most farms in the developing world are too small to justify owning or using a tractor, and the alternatives are animal power or human labor.

For many smallholder farmers, livestock are the only ready source of cash to buy inputs for crop production - seeds, fertilizers and pesticides. Livestock income also goes towards buying things the farmers cannot make for themselves. And that includes paying for school fees, medicine and taxes. Income from cropping is highly seasonal. In contrast, small stock, with their high rates of reproduction and growth, can provide a regular source of income from sales. So can milk and milk products like butter and cheese. Larger animals such as cattle are a capital reserve, built up in good times to be used when crops are poor or when the family is facing large expenses such as the cost of a wedding or a hospital bill.

In the past, farmers could restore the fertility of their land by letting it lie fallow for several years or longer. But as population pressure increases, fallow periods decline or even disappear and different ways of maintaining food production are needed: enter the animal.

Animals are a crucial link in nutrient cycles, returning nutrients to the soil in forms that plants can readily use. They can bring nutrients from pasture and rangeland and concentrate them on crop land through their manure and urine. The animal manure and urine that people in the developed world see as pollutants are vital fertilizers in the developing world. Few smallholders can afford enough mineral fertilizers. Animals give farmers a reason to plant legumes as pastures and cover crops that protect the soil and restore its structure and fertility. According to a Winrock report in 1992, `The greatest threat to [the African rangelands] comes from human populations and expansion of cultivation. There is no solid evidence linking livestock to this process [desertification].'

Increasing the productivity of livestock systems and mixed crop-livestock systems motivates farmers to protect their rangelands and use them sustainably for raising livestock rather than putting them to the plough.

Productive livestock can add value to `idle' land. Already, in many parts of the world mixed crop-livestock systems are the norm, but the importance of the livestock component has been overlooked. Even the language we use tends to reinforce this. When we talk about the non-grain parts of cereal crops, we tend to use terms like `crop residues' or `by-products'. Yet in many farming systems, such as the barley-sheep system of the drier parts of West Asia and North Africa and the tef-based system in the Ethiopian highlands, the farmers value these `by-products' as much as, if not more, than the grain. `Improved' varieties or production packages that overlook the feeding value of these `residues' will find little favor with the majority of farmers.

Intensive animal production in the developed world uses resources that could serve direct human uses - grain that could be eaten by people, land that could produce food crops, electricity that could illuminate and heat people's homes. But in the developing world livestock add value to resources that would otherwise go to waste. Marginal land that cannot -- and indeed should not -- be ploughed; straw, stovers, groundnut haulm, household wastes, all go to feeding livestock in smallholder systems. Cassava peel, for example, feeds goats in humid West Africa. In Syria farmers allow weeds to grow in their cereal fields and then `rogue' them to feed to their sheep. The weeds slightly reduce cereal grain yields, but the productivity of the system as a whole is higher than if they sprayed herbicides to control the weeds. And the environment is protected.

The research task facing the International Livestock Research Institute (ILRI) and its research partners is to develop ways of managing livestock that maximize the benefits to smallholders while minimizing any harm livestock can inflict on the environment. Well-managed, the benefits to smallholders of keeping livestock are overwhelming.

RAISING SWINE

Selection

Buy a weaned pig weighing about 40 pounds, eight weeks old. The hog should have already been wormed. If you are raising swine for eating purposes only, then purchased male pigs should already be castrated, and now referred to as a barrow.

When selecting a pig, choose the healthiest one. Even if you have little experience with swine, it is easy to spot the healthy ones in a litter. Do not pick a small, listless animal or one with obvious defects. Choose one with bright eyes, alert nature and a good appetite.

Feeding

Since feed costs represent 70 to 75% of the cost of swine production, you should carefully analyze all aspects of the feeding program. Swine require various levels of nutrients depending upon size and weight. In general, nutrients can be classified as energy, protein, minerals and vitamins.

Energy is expressed as the amount of total digestible nutrients (TDN). As a general rule, rations that contain 70-80% TDN are adequate for all classes of pigs. Young pigs, up to 77 pounds, need about 16% protein in their diet for optimum growth and development. On the average, a 40-pound pig will eat about 2.75 pounds of 16% protein feed a day and gain 1.10 pounds a day. Barrows will eat slightly more and gain slightly more than gilts, and consequently often cost a little more to purchase. Pigs this age require about a gallon of water per day.

Vitamins and minerals are important in any animal’s diet, and swine are no exception. Most producers will either buy a complete ration from a feed company or purchase a hog supplement to mix with homegrown feeds. If you do the latter, be sure to follow the manufacturer’s instructions. Follow the nutrient requirements closely.

Care and Management

The care and management of the market hog is fairly simple. Usually all you need is to provide pigs with plenty of feed, water and adequate protection from the weather. However, a few other precautions should be followed:

After purchasing your pig, take it home and allow it to get acquainted with the new surroundings. Then you should:
Spray for lice.
Treat for worms with a recommended wormer, once at about 40-50 pounds and again at 100 pounds.
Check with your veterinarian on what shots, if any, are recommended.
Provide feed and fresh water free choice at all times. (Best through the use of self-feeders).
Watch that the pig does not get too hot in the summer. Since swine do not sweat as we do, they may need some help from you. You may need to spray pigs with a fine mist of water on very hot days.
Cleaning the pen frequently and thoroughly will help you to raise your hogs without additional antibiotics and medication.
Keep bedding dry.
Sunshine and fresh air are the cheapest and best disinfectants.
Good nutrition is essential for health.

T.L.E 90

"BASIC ELECTRONICS"

HALF-WAVE RECTIFIER

PARTS AND MATERIALS

Low-voltage AC power supply (6 volt output)
6 volt battery
One 1N4001 rectifying diode (Radio Shack catalog # 276-1101)
Small "hobby" motor, permanent-magnet type (Radio Shack catalog # 273-223 or equivalent)
Audio detector with headphones
0.1 µF capacitor (Radio Shack catalog # 272-135 or equivalent)

The diode need not be an exact model 1N4001. Any of the "1N400X" series of rectifying diodes are suitable for the task, and they are quite easy to obtain.

See the AC experiments chapter for detailed instructions on building the "audio detector" listed here. If you haven't built one already, you're missing a simple and valuable tool for experimentation.

A 0.1 µF capacitor is specified for "coupling" the audio detector to the circuit, so that only AC reaches the detector circuit. This capacitor's value is not critical. I've used capacitors ranging from 0.27 µF to 0.015 µF with success. Lower capacitor values attenuate low-frequency signals to a greater degree, resulting in less sound intensity from the headphones, so use a greater-value capacitor value if you experience difficulty hearing the tone(s).

LEARNING OBJECTIVES

Function of a diode as a rectifier
Permanent-magnet motor operation on AC versus DC power
Measuring "ripple" voltage with a voltmeter

SCHEMATIC DIAGRAM

ILLUSTRATION

T.L.E 51

"HANDICRAFTS"

CANDLE MAKING

The candle making supplies needed are:

1. Candle making wax
2. Wax dye
3. Wicks
4. Fragrance oils
5. Votive molds or containers

Easy stages of candle making

1. Now that you have gotten ingredients, you are prepared to start. Take the wax and rip it up into tiny bits.

2. Now boil the water in the special water boiler and add the smashed wax. Now have your thermometer and be sure the wax warms up to 160 degrees.

3. Mix the candle makers wax and put in your color choice a little at a time until you have the color you want.

4. Now it is best to put in the scent if you are going to utilize one. Be positive the wax stays the right temperature during the mixing and adding.

5. Now cut your candle wicks to the length you think you want. Commence dipping the wick into the hot wax.

6. Pull a piece of wick out and allow it to cool. Continue dipping and cooling until your candle is the size you want.

7. Keep on going until you dip the wick for the final time and let the candle totally cool down.

8. When it has totally cooled, you can commence to trim away the unwanted candle wick and your candle is now ready to use.

STUFFED TOY MAKING

Steps in making stuffed toys

Pick out a fabric you like.
Draw a sketch with a light colored marker (but be sure you can see it) of the animal or person you'd like to make. Be sure to leave about a 1/4 inch of cloth that you'll sew.
Cut out two figures from the sketch you've made. If you want to add anything now, go ahead.
Sew the two together with string inside out (if you drew on it, make sure the side you want on the outside is being sewn on the inside). Make sure to leave a hole to stuff it with!
With the same hole, turn the animal inside out. This hides the stitches and makes it look neater.
Stuff the animal with cotton or other material. Make sure it's not too tight, and don't under stuff it! (lay your head on the animal to see if you're comfortable, since many people sleep with stuffed animals, especially kids)
Sew the hole closed, either by hand or with a sewing machine.
Add embellishments! Take a rounded needle to make the eyes by either using a button or just stitching a circle. Add a mouth with a black yarn or draw one on!
Draw ears on the same cloth (or a different one to mix it up), cut them out, and sew them on. You can add pink fabric to the inside of the ear if you want.
Add all details like tails, ears, eyes, mouth, nose, and even if you want to add hair to the stuffed animal.

T.L.E 40

"CLOTHING AND GROOMING"

SEWING MACHINE

A sewing machine is a textile machine used to stitch fabric or other material together with thread. Sewing machines were invented during the first Industrial Revolution to decrease the amount of manual sewing work performed in clothing companies. Since the invention of the first working sewing machine, generally considered to have been the work of Englishman Thomas Saint in 1790,^[1] the sewing machine has vastly improved the efficiency and productivity of fabric and clothing industries.

Needle plate, foot and transporter of a sewing machine

Singer sewing machine

A Merrow A-Class machine

A Merrow 70-Class machine

A Brother serger.

Home sewing machines are all similar -- designed for one person to manually sew individual items while using a single stitch type. Modern sewing machines are designed in such a way that the fabric easily glides in and out of the machine without the hassle of needles and thimbles and other such tools used in hand sewing, automating the process of stitching and saving time.

Industrial sewing machines, by contrast, are larger, faster, more complex, and more varied in their size, cost, appearance, and task.

The fabric shifting mechanism may be a workguide or may be pattern-controlled (e.g., jacquard type). Some machines can create embroidery-type stitches. Some have a work holder frame. Some have a workfeeder that can move along a curved path, while others have a workfeeder with a work clamp. Needle guards, safety devices to prevent accidental needle-stick injuries, are often found on modern sewing machines.

stitch formations

A series of stitch formations, joining 2 colors of fabric. A zigzag stitch could also be a long, wide continuous seam.

Zigzag are lockstitches with a side-to-side width as well as a stitch length. Basic stitch formation is dictated by a stitch pattern cam; maximum pattern width is established by the stitch width regulator. The cams that produce zigzag stitch patterns are single. As the cam rotates, a fingerlike follower, connected to the needle bar, rides along the cam and tracks its indentations. As the follower moves in and out, the needle bar is moved from side to side. A zigzag stitch has more give than a straight stitch, and therefore is less subject to breakage.

Stretch stitching are produced by coordinated motions of needle and feed. While the needle is moving, as for straight or zigzag stitches, the feed is automatically moving the fabric forward and backward. As with zigzag stitches, stretch stitching is cam controlled, but because of the dual action, stretch stitch patterns have double cams. As the double cam rotates, the follower, connected to a needle bar, rides along one track to move the needle bar from side to side. Another follower, connected to the feed, simultaneously rides the other cam track to move the feed forward and reverse stitches as required by the design.

SKIRT PATTERN

A. Begin by making a "T" - top of the "T" is equal to your waist measurement divided by 6. The sample has a waist of 30", so divide 30" by 6 to equal 5". The vertical line (drawn from the center of the top line) is the skirt length, and our sample is 30".

B. The hipline is normally 8" below the waist, so at that point you'll make a horizontal like equal to hip divided by 6 + 1/4". Our sample hip measurement is 42", so the horizontal line is 7 plus 1/4 or 7 1/4".

C. With a straight yardstick, draw in the outside lines of the skirt, connecting the waist to hip to the bottom and draw in the bottom line.

D. At the top center of the "T" measure down 1/4" and make the slight waistline curve. The outside edges of the bottom are measured up 1/4" each and the slight hemline curve drawn.

E. Make your waistband to equal your waist measurement plus 1 1/2", and the width is 2 1/2" (your finished waistband will be 1 1/4" wide).

T.L.E 70

METALWORK'S AND WELDING

Arc Welding Machine

Safety issues

Correct and safe arc welding station

Welding can be a dangerous and unhealthy practice without the proper precautions; however, with the use of new technology and proper protection the risks of injury or death associated with welding can be greatly reduced.

Heat and sparks

Because many common welding procedures involve an open electric arc or flame, the risk of burns is significant. To prevent them, welders wear protective clothing in the form of heavy leather gloves and protective long sleeve jackets to avoid exposure to extreme heat, flames, and sparks.

Eye damage

The brightness of the weld area leads to a condition called arc eye in which ultraviolet light causes inflammation of the cornea and can burn the retinas of the eyes. Welding goggles and helmets with dark face plates are worn to prevent this exposure and, in recent years, new helmet models have been produced featuring a face plate that self-darkens upon exposure to high amounts of UV light. To protect bystanders, transparent welding curtains often surround the welding area. These curtains, made of a polyvinyl chloride plastic film, shield nearby workers from exposure to the UV light from the electric arc, but should not be used to replace the filter glass used in helmets.^[26]

Those dark face plates must be much darker than those in sunglasses or blowtorching goggles. Sunglasses and blowtorching goggles are not adequate for arc welding protection.

In 1970, a Swedish doctor, Åke Sandén, developed a new type of welding goggles that used a multilayer interference filter to block most of the light from the arc. He had observed that most welders could not see well enough, with the mask on, to strike the arc, so they would flip the mask up, then flip it down again once the arc was going: this exposed their naked eyes to the intense light for a while. By coincidence, the spectrum of an electric arc has a notch in it, which coincides with the yellow sodium line. Thus, a welding shop could be lit by sodium vapor lamps or daylight, and the welder could see well to strike the arc. The Swedish government required these masks to be used for arc welding, but they were not used in the United States. They may have disappeared.^[27]

Inhaled matter

Welders are also often exposed to dangerous gases and particulate matter. Processes like flux-cored arc welding and shielded metal arc welding produce smoke containing particles of various types of oxides. The size of the particles in question tends to influence the toxicity of the fumes, with smaller particles presenting a greater danger. Additionally, many processes produce various gases (most commonly carbon dioxide and ozone, but others as well) that can prove dangerous if ventilation is inadequate. Furthermore, the use of compressed gases and flames in many welding processes pose an explosion and fire risk; some common precautions include limiting the amount of oxygen in the air and keeping combustible materials away from the workplace.^[28]

Arc-Welding Fundamentals

Arc welding is one of several fusion processes for joining metals. By applying intense heat, metal at the joint between two parts is melted and caused to intermix - directly, or more commonly, with an intermediate molten filler metal. Upon cooling and solidification, a metallurgical bond is created. Since the joining is an intermixture of metals, the final weldment potentially has the same strength properties as the metal of the parts. This is in sharp contrast to non-fusion processes of joining (i.e. soldering, brazing etc.) in which the mechanical and physical properties of the base materials cannot be duplicated at the joint.

Fig. 1The basic arc-welding circuit

In arc welding, the intense heat needed to melt metal is produced by an electric arc. The arc is formed between the actual work and an electrode (stick or wire) that is manually or mechanically guided along the joint. The electrode can either be a rod with the purpose of simply carrying the current between the tip and the work. Or, it may be a specially prepared rod or wire that not only conducts the current but also melts and supplies filler metal to the joint. Most welding in the manufacture of steel products uses the second type of electrode.

Basic Welding Circuit

The basic arc-welding circuit is illustrated in Fig. 1. An AC or DC power source, fitted with whatever controls may be needed, is connected by a work cable to the workpiece and by a "e;hot"e; cable to an electrode holder of some type, which makes an electrical contact with the welding electrode.

An arc is created across the gap when the energized circuit and the electrode tip touches the workpiece and is withdrawn, yet still with in close contact.

The arc produces a temperature of about 6500ºF at the tip. This heat melts both the base metal and the electrode, producing a pool of molten metal sometimes called a "e;crater."e; The crater solidifies behind the electrode as it is moved along the joint. The result is a fusion bond.

Arc Shielding

However, joining metals requires more than moving an electrode along a joint. Metals at high temperatures tend to react chemically with elements in the air - oxygen and nitrogen. When metal in the molten pool comes into contact with air, oxides and nitrides form which destroy the strength and toughness of the weld joint. Therefore, many arc-welding processes provide some means of covering the arc and the molten pool with a protective shield of gas, vapor, or slag. This is called arc shielding. This shielding prevents or minimizes contact of the molten metal with air. Shielding also may improve the weld. An example is a granular flux, which actually adds deoxidizers to the weld.

Fig. 2This shows how the coating on a coated (stick) electrode provides a gaseous shield around the arc and a slag covering on the hot weld deposit.

Figure 2 illustrates the shielding of the welding arc and molten pool with a Stick electrode. The extruded covering on the filler metal rod, provides a shielding gas at the point of contact while the slag protects the fresh weld from the air.

The arc itself is a very complex phenomenon. In-depth understanding of the physics of the arc is of little value to the welder, but some knowledge of its general characteristics can be useful.

Nature of the Arc

An arc is an electric current flowing between two electrodes through an ionized column of gas. A negatively charged cathode and a positively charged anode create the intense heat of the welding arc. Negative and positive ions are bounced off of each other in the plasma column at an accelerated rate.

In welding, the arc not only provides the heat needed to melt the electrode and the base metal, but under certain conditions must also supply the means to transport the molten metal from the tip of the electrode to the work. Several mechanisms for metal transfer exist. Two (of many) examples include:

Surface Tension Transfer® - a drop of molten metal touches the molten metal pool and is drawn into it by surface tension.
Spray Arc - the drop is ejected from the molten metal at the electrode tip by an electric pinch propelling it to the molten pool. (great for overhead welding!)

If an electrode isconsumable, the tip melts under the heat of the arc and molten droplets are detached and transported to the work through the arc column. Any arc welding system in which the electrode is melted off to become part of the weld is described asmetal-arc. In carbon or tungsten (TIG) welding there are no molten droplets to be forced across the gap and onto the work. Filler metal is melted into the joint from a separate rod or wire.

More of the heat developed by the arc is transferred to the weld pool with consumable electrodes. This produces higher thermal efficiencies and narrower heat-affected zones.

Since there must be an ionized path to conduct electricity across a gap, the mere switching on of the welding current with an electrically cold electrode posed over it will not start the arc. The arc must beignited. This is caused by either supplying an initial voltage high enough to cause a discharge or by touching the electrode to the work and then withdrawing it as the contact area becomes heated.

Arc welding may be done with direct current (DC) with the electrode either positive or negative or alternating current (AC). The choice of current and polarity depends on the process, the type of electrode, the arc atmosphere, and the metal being welded.

T.L.E 12

"FOOD PROCESSING"

Longganisa Ingredients:

1 kilo ground pork, 10% fat
1/4 cup packed brown sugar
1 tablespoon rock salt (or 1 1/2 teaspoon fine salt)
1 tablespoon worcestershire sauce
3 tablespoons soy sauce
1 tablespoon garlic, chopped
1/2 teaspoon black peper, ground.

Longganisa Cooking Instructions:

Blend all the above ingredients.
Roll a small amount of the pork mixture in a 4 1/2 inches x 3 inches wax paper
Store in the freezer for 3 hours or until ready to cook.

When ready to cook, heat oil in a wok or frying-pan.
Unwrap the sausages and fry in batches in hot oil until fully cooked.
Drain on paper towels.
Garnish with spring onion, if desired, and served with rice and tomatoes or Garlic-Vinegar Dip.
These sausages can also be frozen until needed.

T.L.E 60

"BASIC CARPENTRY AND PLUMBING"

Advantages of Prefabricated Roof Trusses

Trusses span longer distances and eliminate the need for inside load bearing walls.

Less costly than stick roof framing because they are made of shorter lengths of two by four stock as opposed to the larger framing members required of conventional rafter and ceiling framing.

Trusses can be designed for nearly any ceiling or roof combination required in modern custom homes.

Trusses are designed by engineers to meet the roof load and building code requirements.

Trusses can usually be erected in one day, reducing the amount of time the inside of the new home is exposed to outside weather conditions.

Less experienced carpenters can be used to erect trusses, further reducing labor costs.

The Common Roof Truss

The common truss can be recognized by its triangular shape and will make up the bulk of any new home truss package. Common trusses consist of seven main parts;

Top chord

Bottom chord

drywall

Bearing point

Web supports

King post

help support

Metal gussets

supports

Tail

Common Roof Truss

Other Types of Roof Trusses

Types of Roof Trusses

Raised heel

Scissor trusses

Hip

Girder trusses

Mono

Room in attic

Gambrel

camel back

Polynesian

Bowstring

Tri Bearing

Multi piece

Americas

T.L.E 10

"FOOD SELECTION, PREPARATION, AND COOKING"

BEEF 'N PINEAPPLE RECIPE

Ingredients

3/4 pound beef top round steak, cut 1/2-inch thick
1 8-ounce can pineapple slices (juice pack)
2 tablespoons dry sherry or water
1 tablespoon soy sauce
1 tablespoon molasses or brown sugar
1/8 to 1/4 teaspoon crushed red pepper
Nonstick cooking spray
4 green onions, cut into 1/2-inch pieces
1 tablespoon cornstarch
1 medium tomato, cut into wedges
1 6-ounce package frozen pea pods, thawed
2 cups hot cooked rice

Directions

Trim separable fat from round steak. Partially freeze meat; then, cut on bias into thin bite-size strips. Drain pineapple, reserving juice. Cut pineapple slices into quarters; set aside.

In a bowl stir together reserved pineapple juice, dry sherry or water, soy sauce, molasses or brown sugar, and red pepper. Add meat; stir until coated. Cover and marinate meat at room temperature for 15 minutes. Drain, reserving marinade.

Spray a cold large skillet or wok with nonstick cooking spray. Add half of the meat to skillet or wok. Stir-fry for 2 to 3 minutes or until browned. Remove meat. Stir-fry remaining meat and onions for 2 to 3 minutes or until meat is browned. Return all meat to skillet. Push meat from center of skillet.

For sauce, stir cornstarch into reserved marinade. Add sauce to center of skillet. Cook and stir until thickened and bubbly. Add tomato, pea pods, and pineapple. Stir ingredients together until coated with sauce. Cook and stir about 2 minutes more or until heated through. Serve over hot cooked rice. Makes 4 servings.

T.L.E 50

"BASIC ELECTRICITY"

A Basic Circuit

We begin our discussion with a simple example circuit – a flashlight (or “electric torch” as the Brits call it). This has three basic components: a battery, a switch, and a light bulb. For our purpose, the flashlight has two possible states: on and off. Here are two diagrams.

Light is Off Light is On

In the both figures, we see a light bulb connected to a battery via two wires and a switch. When the switch is open, it does not allow electricity to pass and the light is not illuminated. When the switch is closed, the electronic circuit is completed and the light is illuminated.

The figure above uses a few of the following basic circuit elements.

We now describe each of these elements and then return to our flashlight example. The first thing we should do is be purists and note the difference between a cell and a battery, although the distinction is quite irrelevant to this course. A cell is what one buys in the stores today and calls a battery; these come in various sizes, including AA, AAA, C, and D. Each of these cells is rated at 1.5 volts, due to a common technical basis for their manufacture. Strictly speaking, a battery is a collection of cells, so that a typical flashlight contains one battery that comprises two C cells or D cells. An automobile battery is truly a battery, being built from a number of lead-acid cells.

A light is a device that converts electronic current into visible light. Nothing surprising here. A switch is a mechanical device that is either open (not allowing transmission of current) or closed (allowing the circuit to be completed). Note that it is the opp door, which allows one to pass only when open.

The Idea of Ground

Consider the above circuit, which suggests a two-wire design: one wire from the battery to the switch and then to the light bulb, and another wire from the bulb directly to the battery. One should note that the circuit does not require two physical wires, only two distinct paths for conducting electricity. Consider the following possibility, in which the flashlight has a metallic case that also conducts electricity.

Physical Connection Equivalent Circuit

Consider the circuit at left, which shows the physical connection postulated. When the switch is open, no current flows. When the switch is closed, current flows from the battery through the switch and light bulb, to the metallic case of the flashlight, which serves as a return conduit to the battery. Even if the metallic case is not a very good conductor, there is much more of it and it will complete the circuit with no problem.

In electrical terms, the case of the battery is considered as a common ground, so that the equivalent circuit is shown at right. Note the new symbol in this circuit – this is the ground element. One can consider all ground elements to be connected by a wire, thus completing the circuit. In early days of radio, the ground was the metallic case of the radio – an excellent conductor of electricity. Modern automobiles use the metallic body of the car itself as the ground. Although iron and steel are not excellent conductors of electricity, the sheer size of the car body allows for the electricity to flow easily.

To conclude, the circuit at left will be our representation of a flashlight. The battery provides the electricity, which flows through the switch when the switch is closed, then through the light bulb, and finally to the ground through which it returns to the battery.

As a convention, all switches in diagrams will be shown in the open position unless there is a good reason not to.

The student should regard the above diagram as showing a switch which is not necessarily open, but which might be closed in order to allow the flow of electricity.

Voltage, Current, and Resistance

It is now time to become a bit more precise in our discussion of electricity. We need to introduce a number of basic terms, many of which are named by analogy to flowing water. The first term to define is current, usually denoted in equations by the symbol I. We all have an intuitive idea of what a current is. Imagine standing on the bank of a river and watching the water flow. The faster the flow of water, the greater the current; flows of water are often called currents.

In the electrical terms, current is the flow of electrons, which are one of the basic building blocks of atoms. While electrons are not the only basic particles that have charge, and are not the only particle that can bear a current; they are the most common within the context of electronic digital computers. Were one interested in electro-chemistry he or she might be more interested in the flow of positively charged ions.

All particles have one of three basic electronic charges: positive, negative, or neutral. Within an atom, the proton has the positive charge, the electron has the negative charge, and the neutron has no charge. In normal life, we do not see the interior of atoms, so our experience with charges relates to electrons and ions. A neutral atom is one that has the same number of protons as it has electrons. However, electrons can be quite mobile, so that an atom may gain or lose electrons and, as a result, have too many electrons (becoming a negative ion) or too few electrons (becoming a positive ion). For the purposes of this course, we watch only the electrons and ignore the ions.

An electric charge, usually denoted by the symbol Q, is usually associated with a large number of electrons that are in excess of the number of positive ions available to balance them. The only way that an excess of electrons can be created is to move the electrons from one region to another – robbing one region of electrons in order to give them to another. This is exactly what a battery does – it is an electron “pump” that moves electrons from the positive terminal to the negative terminal. Absent any “pumping”, the electrons in the negative terminal would return to the positive region, which is deficient in electrons, and cause everything to become neutral. But the pumping action of the battery prevents that. Should one provide a conductive pathway between the positive and negative terminals of a battery, the electrons will flow along that pathway, forming an electronic current.

Materials are often classified by their abilities to conduct electricity. Here are two common types of materials.

Conductor A conductor is an substance, such as copper or silver, through which
electrons can flow fairly easily.

Insulator An insulator is a substance, such as glass or wood, that offers
significant resistance to the flow of electrons. In many of our
circuit diagrams we assume that insulators do not transmit electricity
at all, although they all do with some resistance.

The voltage is amount of pressure in the voltage pump. It is quite similar to water pressure in that it is the pressure on the electrons that causes them to move through a conductor. Consider again our flashlight example.

The battery provides a pressure on the electrons to cause them to flow through the circuit. When the switch is open, the flow is blocked and the electrons do not move. When the switch is closed, the electrons move in response to this pressure (voltage) and flow through the light bulb. The light bulb offers a specific resistance to these electrons, as a result of which it heats up and glows.

As mentioned above, different materials offer various abilities to transmit electric currents. Those materials that easily conduct electrons we call conductors; those that do not we call insulators. Insulators oppose the flow of electrons to a much greater degree than conductors.

We have a term that measures the degree to which a material opposes the flow of electrons; this is called resistance, denoted by R in most work. Conductors have low resistance (often approaching 0), while insulators have high resistance. In resistors, the opposition to the flow of electrons generates heat – this is the energy lost by the electrons as they flow through the resistor. In a light bulb, this heat causes the filament to become red hot and emit light.