Posted by Nirav Ashara in Top 5 Furniture Restoration Jobs You Should Leave to a Professional, Top 5s on Monday, June 29, 2009
Top 5 Furniture Restoration Jobs You Should Leave to a Professional
5. Wood Furniture
It's not uncommon for beginner do-it-yourselfers to make mistakes restoring wood furniture because many things can go wrong. You must use the right technique, clean with solvents, remove finishes, correctly identify the wood type, sand, match colors and more. Other things that make wood restoration projects tricky are physical strength demands on the laborer, the need for a number of tools, an ideal workspace with natural lighting, storage space if you don't complete it immediately and time (some finishes can take months to dry). Professionals stress that amateurs avoid restoring complex wood furniture such as items that are too heavy to lift, are missing parts or veneer, require upholstery removal, are valuable or have intricate carvings.
4. Ornate, Carved Pieces
Restoring wood furniture can be time-consuming and challenging, especially ornate carvings or intricately shaped features like Barley twist legs on a table. Mistakes made to ornate work can mean damage to the piece or compromising its design and value. According to Mitchell Kohanek with The National Institute of Wood Finishing, accurate restoration involves the understanding of organic chemistry and a mastery of wood-working and wood-finishing skills. It takes Kohanek nine months to prepare someone for a profession in the finishing of wood. He likens the work done by an amateur versus professional to an essay written by a high school student verses English graduate student.
3. Upholstered Gems
If an upholstered furniture piece is of sentimental or financial value to you, perhaps it's worth having restored, rather than trying to conserve original materials and rebuild it yourself. Why? You need about 20 tools to do the job, which can be expensive to rent or purchase. Also, the techniques employed are often tiring, difficult or lengthy. In fact, it's not unusual for the restoration of an upholstered chair to take about 18 hours to complete. There are many cumbersome steps involved, including stripping off old upholstery, cleaning framing and upholstery, repairing frames, finishing, replacing cushion fillings, applying trimming and more.
2. One-of-a-kind Antiques
A furniture piece must be at least 100 years old to qualify as an antique. Museum-quality items should always be restored by a professional. By refinishing common antiques at home, you risk making a mistake that can lower its value, damage the patina that gives it an old look and proves its age, overdo the restoration by replacing more than necessary, or harm the wood's aging process or finish. If you don't know what to look for, you can sand or scrape away desirable marks of age like small, concave grooves created by jack planes used a century ago or numbers chiseled into items in a furniture set to mark their order.
"No inexperienced person should try to restore antique furniture. Period," says Clinton Howell, a member of the National Antique and Art Dealers Association of America, "How many people feel that they could do as good a job defending themselves as their lawyer?"
1. Expensive Furniture
Expensive furniture is costly for a reason. Whatever the reason -- noteworthy design, exceptional durability of materials and construction or rarity in the marketplace -- restoration can also be pricey. So can mistakes. Steer clear of refinishing a costly furniture piece if you can't afford to buy a replacement that's identical or similar in quality if you botch the job. Consequences of an uncorrectable mistake can be hundreds of thousands of dollars. Also, if that piece is no longer for sale, or if it would be difficult to find (and you don't have the time or resources to track it down), consider turning it over to a professional for restoration.
Posted by Nirav Ashara in What if I were on a roller coaster and the safety harness broke?
What if I were on a roller coaster and the safety harness broke?
A roller coaster loop-the-loop is a sort of centrifuge. As youapproach the loop, your velocity is straight ahead of you. But the track keeps the coaster car, and therefore your body, from traveling along this straight path. The car starts to turn upward and your velocity is trying to carry you straight ahead. The force of your inertia pushes you into the car floor. This creates a sort of false gravity pulling you toward the bottom of the car when you're upside down. You need a safety harness for security, but in most loop-the-loops, you would stay in the car whether you had a harness or not.
As you move around the loop, the net force acting on your body is constantly changing. At the very bottom of the loop, the acceleration force is pushing you down in the same direction as gravity. Since both forces push you in the same direction, you feel especially heavy at this point. As you move straight up the loop, gravity is pulling you into the back of your seat while the acceleration force is pushing you into the floor. You feel the gravity pulling you into your seat, but (if your eyes are still open) you can see that the ground is no longer where it should be.
At the top of the loop, when you're completely upside down, gravity is pulling you out of your seat and toward the ground, but the stronger acceleration force is pushing you into your seat and toward the sky. Since the two forces pushing you in opposite directions are nearly equal, your body might feel very light. It depends on how fast the car is going and how tight the loop is. As you come out of the loop and level out, you become heavy again.
This diagram demonstrates the force of gravity on your
weight while you ride a roller coaster.
The loop-the-loop is amazing because it crams so much into such a short length of track. The varying forces put your body through a whole range of sensations in a matter of seconds. While these forces are shaking up all the parts of your body, your eyes see the entire world flip upside down. To many coaster riders, this moment at the top of the loop, when you're light as a feather and all you can see is the sky, is the best part of the whole ride.
Posted by Nirav Ashara in How to Air Condition Your Home and Not Sweat the Cost on Friday, June 12, 2009
How to Air Condition Your Home and Not Sweat the Cost
I’ve caved to the summer heat. For a while, I was determined to win the good fight by turning on fans, wearing shorts and sandals exclusively and leaving doors ajar to let the fresh breezes blow in. But when I trudged inside after mowing the lawn and was greeted by a blanket of warm, stale air, I hit my breaking point. Reluctantly, I’ve turned on my air conditioner. And in exchange, the prospect of skyrocketing energy bills haunts me.
If you’ve noticed your power bill creeping up in recent weeks, you aren’t crazy. The kilowatt per hour rate, the pricing unit for electricity, is going up as summer energy rates set in. Moreover, Energy Star states that the average household shells out $1,000 per year on home heating and cooling, which sends shivers down my spine.
But there are ways to stay comfortably cool indoors without going broke. You can’t live in arctic conditions, but you won’t have to swelter through the night, either. Start out by setting the thermostat to 78 degrees, which most energy experts advise as the optimal summer temperature. Then, follow the five tips below to shave off more kilowatt hours from your next power bill.
Turn it down when you’re not home : The U.S. Department of Energy urges consumers to set thermostats 10 to 15 degrees warmer when they leave home. The closer the indoor temperature matches the outdoor temperature, the less power the air conditioner burns.
See how high you can go: For every degree you raise the temperature, the South Carolina Energy Office says you can save up to 5 percent on cooling costs. If things get steamy, turn on a fan.
Block out the sun: Shades, blinds and curtains insulate against heat from the sun, saving you money and keeping the house cooler.
Keep the unit clean: Clear away brush and debris from around outdoor units to improve efficiency. Energy Star also recommends checking the indoor and outdoor coil to make sure they’re clean.
Don’t block airflow: If you’ve blocked vents with furniture or anything else, move it out of the way. Also, change air filters monthly to make sure the cool breezes can get through to begin with.
Following these tips will also give you a head start on cutting winter energy costs. That way, you’ll save some green year round.
Posted by Nirav Ashara in How WiFi Detectors Work, Mechanics of WiFi Detectors, Using WiFi Detectors on Wednesday, June 10, 2009
How WiFi Detectors Work
Hotspot: This trendy term has taken the Internet-addicted population by storm. If you're not very tech-savvy and aren't familiar with it, take a look when you stroll by cafes and restaurants or the next time you go to the airport. You'll probably see signs letting people know that the location is a WiFi hotspot. You'll also probably notice several preoccupied people with noses buried in their laptops. A WiFi hotspot is simply a place where you can access wireless Internet. In the past few years, WiFi access has seeped into more and more places and facilities.
WiFi access has become so prevalent that it's turned many people into laptop-toting, Internet hunters on the prowl for a signal everywhere they travel. When they reach a place that fits the typical characteristics -- sells books or coffee and has tables or comfy chairs -- they can pretty safely expect to find a WiFi signal. But now that many buildings, college campuses and other kinds of facilities are adopting WiFi, the hunt for a signal is getting more interesting.
Unlike coffee shops that want to attract more customers, other facilities may not make it very obvious if they have a WiFi signal. In this way, the search has become more challenging. There's nothing more frustrating than taking o ut and booting up your laptop only to find that there's no signal. You'll have to pack up all your stuff, move on and try again. Some poor souls desperate for a signal will wander aimlessly with their laptops open waiting for a sign of wireless life.
After all this rigmarole, you've wasted time, patience and precious laptop battery power. Fortunately, however, there's an alternative. Certain devices have emerged that will help relieve the wandering wireless syndrome: WiFi detectors. Next, we'll explore the technology behind these useful travel gadgets.
Mechanics of WiFi Detectors
A wireless signal can travel only so far. Specifically, a typic al signal can extend as far as 1,000 feet (304.8 meters) in an unobstructed, open area and about 300 feet (91.44 meters) in a closed area that has obstructions [source: Graves]. Because the signals themselves are invisible and the access points (routers) that emit them are usually hidden, a WiFi detector can be a handy tool. WiFi detectors are basically just gadgets that can quickly and easily tell you whether you're around a WiFi signal.
Before we can understand the mechanics of WiFi detectors, let's take a quick look at wireless Internet. Although wireless Internet travels in waves similar to radio waves, it travels on very different frequencies. It actually travels on frequencies significantly higher than those of other common devices, such as cell phones. These frequencies that carry wireless Internet fall into the ranges of 2.4 GHz or 5 GHz, depending on the standard used.
In order to standardize the wireless Internet process, a group called the Institute of Electrical and Electronics Engineers (IEEE) has specified 802.11 as the group of networking standards it uses. Such standards specify how data travels through the waves. Different letter-signifiers further specify the set of standards. Some common ones are 802.11b and 802.11g, both of which use the 2.4-GHz band. Within the 2.4-GHz band, you have specific channels. In the United States, wireless Internet has 11 available channels on the 2.4-GHz band (other countries may have fewer or as many as 14).
Using WiFi Detectors
As we mentioned, all WiFi detectors have interfaces that somehow inform you if a wireless signal is present. Apart from this basic function, however, all detectors are different. Manufacturers have come up with many methods for conveying the information to the user, and some of these gadgets are able to provide more information than others.
Many use LED lights, for instance. These typically light up in a scale fashion, where a single light indicates a weak signal, and more light up in sequence as the signal gets stronger. More advanced detectors use an LCD screen to display some useful information. Not only will it tell you the degree of signal strength, but perhaps also the SSID (Service Set Identifier), which is basically the name of the network. This would alert you to whether the wireless signal it's picking up is coming from your own home network or the neighbor's.
Detectors might also list the operating channel on which the network is working. This is helpful for reducing interference. It turns out that multiple networks working within the same proximity in the 2.4-GHz band can cause interference for each other. If you remember from the previous page, the 2.4-GHz band has 11 available channels in the United States. Interference can be reduced by spreading WiFi networks farther apart across the channel numbers. Thus, if your detector informs you that your neighbor's network is using channel 6, tune your router to channel 1 or 11.
When using WiFi detectors, remember that they run on batteries (usually AAA), so don't leave them on when you're not using them. Many include an indicator of battery that lets you know if it's in need of a replacement soon. Some actually have different settings that allow you to control the battery consumption or let you plug into your computer's USB port to charge.
Another helpful feature is that some detectors can tell you if the signal is encrypted (secured). If it's encrypted, you'll need a password to use it. Unfortunately, some people who travel around looking for unencrypted wireless signals might use this feature against you. When you leave your network unencrypted, freeloaders might snoop into your Internet activities or perform illegal downloads (such as music sharing). Authorities looking for the perpetrators could trace these downloads to your network, and you could get wrapped up in legal frustrations even if they can't ultimately pin the fault on you. So, it's important to keep your wireless network secure and encrypted with password protection.
Overall, when you travel with a laptop, a WiFi detector can be one of the handiest travel gadgets to bring with you. You can even get a small keychain version to ensure you never leave home without it.
Posted by Nirav Ashara in Alternative fuel vehicle pictures on Monday, June 8, 2009
Alternative fuel vehicle pictures
Posted by Nirav Ashara in Top 5 Ways We'll Have Fun in 2050, Top 5s
Top 5 Ways We'll Have Fun in 2050
5: Bird Watching
While you may have hoped for some futuristic gossip in this article, you'll be very familiar with one activity: bird watching. In 1997, Newsweek published a list of outdoor activities and their expected rate of growth by 2050, and bird watching far outpaced the rest. In fact, back then, bird watching was estimated to grow faster than the projected population of the United States, with a growth rate of about 58 percent. By 2050, there may be as many as 127.8 million birders.
When bird enthusiasts spot a new find in the future, it will be a pretty big deal. That's because by 2050, the existence of about 400 to 900 species of land birds will be threatened thanks to climate change and habitat destruction. So if you relish in the excitement of a rare find, then you have lots of exciting opportunities to await you.
If you consider bird watching to be too much of a fuddy-duddy hobby, consider the fact that the population will be fairly elderly in 2050; in fact, seniors will make up a quarter of all Americans. There's a large number of baby boomers, and they're aging during a time in which we're discovering life-elongating technologies every day. With more years to fill, it may be time now to invest in a good pair of binoculars.
4: Jellyfish Restaurants
It's hard to imagine a time when friends and family won't meet up for a bite to eat, so of course we're including dining out on our list. However, don't plan on heading to a local steakhouse or burger joint. Because of factors including land use, population and water supply, the American diet will undergo some changes by 2050. We'll be eating a lot more grains and beans and a lot less meat and dairy. We'll still eat our veggies, of course, but we won't have the wide array to choose from that we enjoy today. Futurists estimate that about 15 percent of our diet will be from animal products, and the rest will be from plants; the United States as a whole may have to stop exporting food by 2025.
If a juicy burger isn't an option, where will those animal products come from? One possibility is that we'll eat more fish, but we certainly won't be eating the tuna and cod that we're accustomed to. According to reports published in the journal Science in 2006, commercial fish stocks could be completely decimated by 2050 because of overfishing and pollution. Our fishing throws aquatic ecosystems off balance in irreparable ways; for example, by fishing for tuna, marlin and swordfish, we eliminate the major predators of jellyfish. As a result, jellyfish numbers are increasing rapidly, which may mean that we'll have to develop a taste for jellyfish sushi. Jellyfish have been eaten for thousands of years in Asian countries, but its taste may require some getting used to -- one biology professor described it as "tough strips of cucumber". One slightly more palatable option we might have in 2050 is squid, which unfortunately are very high in cholesterol.
3: Robot Soccer Games
It's difficult to even comprehend all the ways we might interact with robots by 2050. It's possible that robots will be conducting routine surgeries or piloting our airplanes. They could be conducting search and rescue missions or fighting in wars. One researcher even predicts that by 2050, we could be having sex with and marrying robots.
But when it comes to having fun either now or in 2050, you'd be hard pressed to find a better way to spend a Saturday or Sunday than outside in the beautiful sun, enjoying a sporting event. What might change by 2050, though, is who's playing. Roboticists predict that by 2050, they will have developed autonomous robots that will be able to beat the best soccer players in the world. That's right, by 2050, we could see Robots vs. Humans in the contest for the World Cup. Now that will fill some bars and basements!
These robots won't just be wired with the steps for winning a soccer game. Rather, roboticists are working now to train robots how to play soccer by using human models. The robots are presented with data that shows how humans respond to a series of soccer plays, so that when the robot is presented with the same setups, they have choices in how to respond. These robots will be able to perceive the play and act accordingly. If you want a glimpse of the future, check out the RoboCup games, in which researchers test out their current "players" and share information with one another. So far, there are no robotic concession workers for these events.
2: Oral Storytelling
Currently, many of us spend our spare time using social media like Twitter and blogs, mediums that allow us to type up a quick message to let our friends know what we're doing. However, writing and reading those messages may not be how we communicate with our pals in the future. In fact, we may not read or write at all, a future that many dying newspapers are already confronting.
Futurist William Crossman believes that spoken language will replace written communication in the coming years, meaning that we won't need to teach children how to read and write, but rather how to use computers and think creatively [source: Naisbitt]. Crossman envisions a world in which we all use voice-in, voice-out (VIVO) computers. Everything we need to communicate will be handled by these machines. Rather than writing our memoirs, for example, we'd sit down in front of a webcam and tell our story. As the recent rise of reality television and YouTube superstars bears out, there are many people who would happily sit and watch a complete stranger spin a tale.
Crossman's future means that vast swaths of the population will be illiterate, but should those people need to read something, their computer could scan and read it to them. In some ways, this may make communication more democratic, and with the explosion in populations that are predicted, it may even be necessary. Computers would have instantaneous translation services, making it easier for an urban resident to connect with a rural resident a world away.
1: Virtual Reality Entertainment
Your flat-screen television may represent the epitome of entertainment right now, but by 2050, it will seem hopelessly outdated. In 2050, we'll likely demand that our entertainment not be contained by the screen -- we'll want to interact with it via virtual reality. Imagine playing a video game about World War II: You and your friends will have the option of hopping off the couch and storming the beaches of Normandy with everybody else. With this technology, your children will be able to interact with their favorite fuzzy friends by inviting them into the living room to dance around.
Entertainment won't be the only way we'll use virtual technology, however. Likely, we'll be able to meet up with friends and family around the world thanks to hologram technology. Let's say you have a business meeting with colleagues from New York, Seattle and Beijing -- all of you can meet up in one office to discuss the matter at hand. Long-distance relationships will become a little more manageable because of virtual visits, and all of your pals can show up to your destination wedding, no matter where they live.
Posted by Nirav Ashara in What is the difference between drywall and plaster? on Sunday, June 7, 2009
What is the difference between drywall and plaster?
When building a home or remodeling, people usually think about the granite countertops, the extensive square footage or the number of windows in the new space. Much of the time, little thought is given to one of the most integral parts of the home -- the interior walls.
Most people don't think about the walls in their homes unless there's a problem or they move into a studio apartment. Yet, interior walls provide privacy and separation. They can also act as sound barriers, insulators and even offer additional fire resistance.
Two of the most common forms of interior wall materials are plaster and drywall. Plaster has been used since ancient times. The earliest plaster was usually made of lime, sand, animal hair and water. Egyptian tombs, such as that of Queen Nefertari, feature paintings on the plaster walls that line their interiors. Ancient Roman homes are known to have been decorated with fresco artwork. Frescos are works of art that are created with different pigments on wet plaster.
An alternative to lime-based plasters, gypsum-based plasters had a faster drying time . This new form of plaster grew in popularity because it could speed up the building process.
As technology advanced, drywall became more durable and readily available. By the 1950s, drywall had surged in popularity as an interior wall material. The product now covers a majority of the interior walls in modern day homes.
In this article, we'll explore the composition, advantages and disadvantages of plaster and drywall for interior wall applications.
Inside Plaster
The most common form of plaster for interior walls is gypsum plaster. Plaster walls are generally created through a three-coat process. To begin, lath must be secured to the framing. Historically, lath has been made of wood strips, but more recently metal or plasterboard have come into use. The lath gives the gooey plaster something to hold onto.
After the lath is in place, the plaster compound must be mixed. The compound usually comes dry and must be mixed with water. While this step may sound fairly easy, a certain amount of skill and experience is needed to get the right consistency [source: Nash]. Then, the plaster can finally be applied to the wall. The first coat of plaster is applied, scratched and left to dry. It is followed by the second coat, or brown coat, and then the wall is finished off with a final layer.
Due to the number of coats and lathing, a plaster wall tends to be thicker than a drywall wall, which can create a greater air barrier [source: Heberle and Scutella]. This thickness also creates a good sound barrier between rooms. If the lathing and framing are done well, plaster can provide a much more rigid wall leading to reduced likelihood of buckling or breaking. Since plaster is not a solid when it's applied to the wall, it can be a good choice for curved or irregular surfaces. Finally, the gypsum within the plaster has a high water content, which gives the walls fire-resistant qualities.
Even with these benefits, plaster has fallen out of favor with homeowners today. Let's look at some possibilities for why that might have happened. First, the plastering process is labor intensive, causing the price to rise. Plastering is also time-consuming -- in applying and drying time. In addition, while plaster is very durable, it can crack with the settling of the building or improper installation. Some of these cracks can be fixed with plaster or a setting-type compound, yet others require structural restoration.
These may be some of the reasons that homeowners and remodelers are now more likely to opt for the drywall. Let's take a closer look at this interior wall material.
Inside Drywall
For basic gypsum drywall, the calcined gypsum is mixed with water and occasionally additives to create the core material. The viscous material is then squeezed, or flattened, between two different layers of paper and dried. One side of the paper is the face, which is strong and smooth, while the other side, or back, has a rougher texture.
Installing drywall is a fairly quick process compared to that of plastering. The boards are cut to fit the shape of the walls. They're then secured to the rough framing of the house. After the boards are in place, corner bead is attached to the corners to give them a straight edge. The walls are then taped with either paper or fiberglass-mesh tape at the joints, corners and places where the boards have been fastened to the wall. Then, the typical three layers of joint compound are added. After each layer, the wall is sanded to give a smoother surface. Once the third layer had dried, the wall is ready to be painted.
There are obvious advantages to drywall over plaster. First, the process of installation requires less time and labor, which can translate to less cost. Drywall also helps to reduce noise along with having fire-resistant properties due to the water in the boards.
While drywall does have many advantages as an interior wall material, it's not invincible. Drywall can be damaged by the settling of the building or homeowner accidents. A common problem is nail or screw pops, when the head of these fasteners creates a bulge or becomes visible through the drywall.
Secondly, gypsum drywall is susceptible to water damage if exposed to elevated levels of moisture over long periods of time. There are specialty drywall boards with additives that are designed for better water-resistance.
Along with water sensitivity, gypsum drywall boards can have mold problems. To decrease the chance for mold, new gypsum drywall boards are going paperless.
Whether you choose the versatility of drywall or the old-world charm of plaster walls, interior walls shape the look, flow and feel of your home. Knowing about the advantages and disadvantages of both plaster and drywall help you to choose the best system for your lifestyle.
Posted by Nirav Ashara in Fireworks Displays, How Fireworks Work on Wednesday, June 3, 2009
How Fireworks Work
If you have ever been to an aerial fireworks show at an amusement park, baseba ll game, Fourth of July celebration or on New Year's Eve, then you know that fireworks have a special and beautiful magic all their own -- a good show is absolutely amazing.
Have you ever wondered how this magic works? What is launched into the sky to make these beautiful displays? In this article, you will learn all about firecrackers, sparklers and aerial fireworks.
Firecrackers and Sparklers
Just about everyone in the United States has some personal experience with fireworks, either from Fourth of July or New Years Eve celebrations. For example, you have probably seen both sparklers and firecrackers. It turns out that if you understand these two pyrotechnic devices, then you are well on your way to understanding aerial fireworks. The sparkler demonstrates how to get bright, sparkling light from a firework, and the firecracker shows how to create an explosion.
Firecrackers have been around for hundreds of years. They consist of either black powder (also known as gunpowder) or flash powder in a tight paper tube with a fuse to light the powder. Black powder, contains charcoal, sulfur and potassium nitrate. A composition used in a firecracker might have aluminum instead of or in addition to charcoal in order to brighten the explosion.
Sparklers are very different from firecrackers. A sparkler burns over a long period of time (up to a minute) and produces extremely bright and showery light. Sparklers are often referred to as "snowball sparklers" because of the ball of sparks that surrounds the burning portion of the sparkler. If you look at Patent #3,862,865: Sparkler composition, you can see that a sparkler consists of several different compounds:
- A fuel
- An oxidizer
- Iron or steel powder
- A binder
See this Question of the Day for a discussion of oxidizers -- potassium nitrate is a very common one. The fuel is charcoal and sulfur, as in black powder. The binder can be sugar or starch. Mixed with water, these chemicals form a slurry that can be coated on a wire (by dipping) or poured into a tube. Once it dries, you have a sparkler. When you light it, the sparkler burns from one end to the other (like a cigarette). The fuel and oxidizer are proportioned, along with the other chemicals, so that the sparkler burns slowly rather than exploding like a firecracker.
It is very common for fireworks to contain aluminum, iron, steel, zinc or magnesium dust in order to create bright, shimmering sparks. The metal flakes heat up until they are incandescent and shine brightly or, at a high enough temperature, actually burn. A variety of chemicals can be added to create colors.
Aerial Fireworks
An aerial firework is normally formed as a shell that consists of four parts:
- Container - Usually pasted paper and string formed into a cylinder
- Stars - Spheres, cubes or cylinders of a sparkler-like composition
- Bursting charge - Firecracker-like charge at the center of the shell
- Fuse - Provides a time delay so the shell explodes at the right altitude
Located just below the shell is a small cylinder that contains the lifting charge.
The shell is launched from a mortar. The mortar might be a short, steel pipe with a lifting charge of black powder that explodes in the pipe to launch the shell. When the lifting charge fires to launch the shell, it lights the shell's fuse. The shell's fuse burns while the shell rises to its correct altitude, and then ignites the bursting charge so it explodes.
Simple shells consist of a paper tube filled with stars and black powder. Stars come in all shapes and sizes, but you can imagine a simple star as something like sparkler compound formed into a ball the size of a pea or a dime. The stars are poured into the tube and then surrounded by black powder. When the fuse burns into the shell, it ignites the bursting charge, causing the shell to explode. The explosion ignites the outside of the stars, which begin to burn with bright showers of sparks. Since the explosion throws the stars in all directions, you get the huge sphere of sparkling light that is so familiar at fireworks displays.
Multibreak Shells
More complicated shells burst in two or three phases. Shells like this are called multibreak shells. They may contain stars of different colors and compositions to create softer or brighter light, more or less sparks, etc. Some shells contain explosives designed to crackle in the sky, or whistles that explode outward with the stars.
Multibreak shells may consist of a shell filled with other shells, or they may have multiple sections without using additional shells. The sections of a multibreak shell are ignited by different fuses. The bursting of one section ignites the next. The shells must be assembled in such a way that each section explodes in sequence to produce a distinct separate effect. The explosives that break the sections apart are called break charges.
Fireworks Displays
T he pattern that an aerial shell paints in the sky depends on the arrangement of star pellets inside the shell. For example, if the pellets are equally spaced in a circle, with black powder inside the circle, you will see an aerial display of smaller star explosions equally spaced in a circle. To create a specific figure in the sky, you create an outline of the figure in star pellets, surround them as a group with a layer of break charge to separate them simultaneously from the rest of the contents of the shell, and place explosive charges inside those pellets to blow them outward into a large figure. Each charge has to be ignited at exactly the right time or the whole thing is spoiled.
To see how some common multibreak shells look in the sky, try the quick and easy "HowStuffWorks Field Guide to Aerial Fireworks." It's interactive, so you can click on a name and see the fireworks display that goes with it. The next time you witness a big fireworks show, you will know the names for each type of shell you see.
You can see how some of the more common multibreak shells look in the sky by clicking on the buttons in the illustration above. You can read descriptions of these shells below:
- Palm: Contains large comets, or charges in the shape of a solid cylinder, that travel outward, explode and then curve downward like the limbs of a palm tree
- Round shell: Explodes in a spherical shape, usually of colored stars
- Ring shell: Explodes to produce a symmetrical ring of stars
- Willow: Contains stars (high charcoal composition makes them long-burning) that fall in the shape of willow branches and may even stay visible until they hit the ground
- Roundel: Bursts into a circle of maroon shells that explode in sequence
- Chrysanthemum: Bursts into a spherical pattern of stars that leave a visible trail, with an effect somewhat suggestive of the flower
- Pistil: Like a chrysanthemum shell, but has a core that is a different color from the outer stars
- Maroon shell: Makes a loud bang
- Serpentine: Bursts to send small tubes of incendiaries skittering outward in random paths, which may culminate in exploding stars
Posted by Nirav Ashara in Bonus Post, Extreme Hard Drive Repair, Hard Drive Repair, How To Recover Lost Data from Your Hard Drive, Signs of Hard Drive Failure, Why Drives Fail on Monday, June 1, 2009
BONUS POST
How To Recover Lost Data from Your Hard Drive
Hard drives fail. It's a fact of life for anyone who uses a computer. If you store irreplaceable information on your hard drive, then a failure can be a catastrophe. But can you recover the family photos, work documents or financial data that you kept meaning to back up, but never did? There might be hope, so don't give up on that broken hard drive yet.
We're going to describe the warning signs of a hard drive failure, explain the internal parts of a hard drive and why they fail, and then we'll go through a few steps you can take to recover your data. While the files can't always be recovered, there's a chance you might be able to retrieve them.
Just remember one thing -- even if your files can be restored, it will take hours of frustrating effort and might cost you quite a bit of money, too. The best way to fix a dead hard drive is to send it in under warranty and replace it with your backup drive that has all your files safely stored on it. In fact, after reading this article, you'll find that a good back-up plan will keep you from ever experiencing the horrible feeling in the pit of your stomach when you realize that all of your files may be gone.
Why Drives Fail
A hard drive is a mechanical device with several moving parts. Magnetic platters store the data itself, while a motorized spindle spins the platters. A read/write arm moves across the platters, retrieving information or putting down new data. The arm is moved by an actuator, and the read/write heads themselves hover an infinitesimal distance above the platters. The distance is so small that a single piece of dust can get in the way.
If any of the hard drive's mechanical parts fails, the whole drive will fail. The parts operate with incredible precision, so hard drives are rather fragile. Circuit boards, spindle motors, ball bearings -- any of these parts are susceptible to failure. The worst type of failure is known as a head crash. In this case, the read/write head drops down directly onto the platter and scrapes away the magnetic material. The data in that case is totally, permanently lost. Data on unaffected parts of the platters may be recoverable, but usually data are spread around the platters, so a head crash is really bad news.
Other mechanical failures can be both a curse and a blessing. It's a curse because it can be difficult and expensive to get replacement parts and find someone who can make the repair. It's a blessing because, as long as the platters weren't damaged, the data are still there. If you can get the drive running again, the data should be accessible.
The failure might be non-mechanical. Your computer uses a special index and file structure to read all the files stored on the disk. If this index becomes corrupted, the computer won't be able to see or read the data, even though it's still there. In many cases, this can be repaired with the proper software, although it can be tricky.
There's one last area where a drive can fail, and it's particularly insidious because the drive actually didn't fail at all -- the drive's connection to your computer failed. Hard drives connect to your computer's motherboard via a variety of interfaces, IDE, PATA and SATA being the most common. If this connection, or the circuit on the motherboard that controls the disk (called the disk controller) has failed, the symptoms can mimic the symptoms of a hard drive failure.
The next section will describe the warning signs of impending hard drive failure.
Signs of Hard Drive Failure
All too often, hard drives fail with no warning whatsoever. One minute the computer is working fine, the next you have a "blue screen of death" and all your data is gone. So, what's the lesson here? Don't rely on warning signs to predict hard drive failure. Assume that your hard drive is going to fail, and back up critical files. If you have a reliable back-up, you'll save yourself many headaches.
Some mechanical components can fail gradually, however, so occasionally you'll know when a drive failure is imminent. These warnings fall into two categories: sounds and performance problems.
If you spend a lot of time sitting near your computer, you're probably familiar with the usual sounds it makes. If you hear the hard drive making any unusual noises, that's probably a clue that something is going wrong. Grinding or screeching noises might mean the bearings or spindle motor are failing. A clicking, clunking or clanging sound could be the read/write arm slamming back and forth. Sometimes these sounds can be subtle and difficult to detect. If you think you're hearing funny noises, open your computer's case and listen with your ear close to the hard drive while someone else uses the computer to save or move some files.
Performance problems include a sudden increase in the frequency of freeze-ups and crashes. Of course, these types of performance problems can be symptomatic of any number of computer maladies, from viruses to memory leaks to non-drive related hardware failures. A more specific tell-tale: saving or moving files suddenly takes a very, very long time. When you run into any of these symptoms, back up anything that isn't already saved and hope the drive lasts long enough to get everything you need copied to another disk.
Next, we'll troubleshoot your dead drive.
Troubleshooting a Dead Drive
When your drive seems to have given up the ghost, there are some steps you can take to determine where the problem lies. If your computer is running Windows, the first thing you should do is reboot the computer and go into the basic input/output system (BIOS). Usually you do this by pressing the Delete key during the boot-up sequence -- watch for on-screen prompts. BIOS has a utility that autodetects drives. Run this and see if the drive shows up. If it doesn't, there may be a problem with the connections between the drive and the motherboard. Check all those connections.
If the drive does show up, then you can run some more diagnostic tests. You'll need another functional computer to accomplish most of these, unless you've planned ahead. Find the model number and manufacturer of your hard drive. Go to the manufacturer's Web site and look for the company's proprietary diagnostic software. You'll have to download and then burn it to a CD-ROM or save it to a floppy disk, depending on what the "dead" computer is equipped with. Boot the dead computer from the diagnostic disk and run it. The diagnostics should give you some indication of what the problem is, although sometimes it will find no problems, even though the drive is still not working.
You can also create a bootable virus scan disk and scan the dead drive for any viruses that might be causing the problem. If your computer is infected, you may be able to use the virus scan disk to repair the problem as well.
If all has gone well, at this point you should have a rough diagnosis. You might not know exactly what's wrong, but at least you've ruled some things out and narrowed it down. But what if none of those troubleshooting steps worked? Try connecting the drive to another computer, one that you know works. This will let you know if the problem is really with the drive itself.
Also, open your computer's case and listen closely to the drive when you boot up the computer. Is it totally silent? That means the platters aren't "spinning up," indicating a serious mechanical problem. Does it make any of the warning sounds we mentioned earlier? Remember, these are also a sign of mechanical failure. If it sounds perfectly normal (generally, a steady hiss as the platters spin and internal cooling fans activate -- although different drives make different sounds), then the problem is probably not mechanical.
In the next section, we'll explore some different ways to repair a hard drive.
Hard Drive Repair
f you've determined that your drive has a mechanical problem, you may have some difficulties to overcome. The drive might be fixable and your data recoverable, but it might require a professional repair, which can cost hundreds or even thousands of dollars. The main reason for this is that work on the internals of a hard drive have to be done in a "clean room" environment. Any piece of dust on the platters can ruin the drive.
You could attempt a mechanical repair on your own, but you'll need to find exact replacement parts from the exact model and version of the drive. This can be a huge challenge all by itself (even for professional data recovery experts). You might be able to replace a dead circuit board yourself, but spindle motors and read/write actuators are very difficult to deal with. Also note that opening your hard drive's case will void its warranty. If you do decide to go this route, remember to never touch the platters themselves. The oils from your fingertips are enough to ruin the drive.
A problem with a corrupt file structure or disk index is solved with special software. There are some utilities, such as fdisk, built into most operating systems that can be used for this purpose, but you have to be very careful. Changing the partitions in the drive or formatting it might solve the problem, but you'll lose all your data. Another option is to use a specialized recovery utility such as Disk Warrior to repair the problem while keeping as much of your data as possible. Some corrupted files may not be recoverable.
Up next, a look at some extreme forms of hard drive repair.
Extreme Hard Drive Repair
There are some rather odd hard drive repair suggestions floating around the Internet. Enough people claim that they work that they're worth a look in dire circumstances. If your drive seems to have a mechanical problem or simply a problem you haven't been able to solve, and you're unwilling or unable to get professional data recovery, you might have one last ditch shot at retrieving your data.
Before you try any of these techniques, make sure you're ready to immediately recover your data. The easiest way is to have the connections ready to reconnect the dead drive to a computer with either a DVD burner or a large flash drive to move your critical files to. Also, please remember that these methods may not work and may even cause additional damage to your hard drive. If you have any questions about what you're doing, it's probably best to have a professional look at your hard drive for you.
Sometimes the mechanical parts within a hard drive can get bound up or jammed. A sharp physical shock might free things up long enough to get your data. Keep in mind this is the exact opposite of how you should normally treat a hard drive, so this is really a last resort. First, try whacking the side of the drive with the handle of a screwdriver or a small mallet. If that doesn't help, try the drop method: Hold the drive about 6 inches (15.2 centimeters) above a hard surface and let it fall (make sure the metal chassis is the part it lands on). You might have luck with successive drops from slightly higher up.
The most unusual method of hard drive repair requires you to freeze the drive. The cold temperature shrinks certain metal parts and can free up jams or binds. Put the drive in a sealed plastic bag and then put it in the freezer. Reports vary from a minimum of two hours to 24. If you have nothing else to lose, it's worth a try.
There are some even more extreme forms of hard drive repair, but they can only be accomplished by professionals. Some of these techniques can recover data from drives that have been burned and melted in fires or damaged by water. Even drives that were submerged in floods can have recoverable data on them. The methods involve recovering the platters and using new mechanical parts to read whatever magnetic data is still on them. This absolutely has to be done in a clean room, so there's really no way to do it in your own home. It's expensive, but if you absolutely need that information, it may be worth it to you. Thats all.