引用内容

• If you use an ODBC or OLE DB call to start transactions, there is a difference in behavior between SQL Server Native Client and MDAC; transactions will begin immediately with SQL Server Native Client, but transactions will begin after the first database access using MDAC. This can affect the behavior of stored procedures and batches because SQL Server requires @@TRANCOUNT to be the same after a batch or stored procedure finishes execution as it was when the batch or stored procedure started. See Rollbacks and Commits in Stored Procedures and Triggers for more information.
  
  
• With SQL Server Native Client, ITransactionLocal::BeginTransaction will cause a transaction to be started immediately. With MDAC the transaction start was delayed until the application executed a statement which required a transaction in implicit transaction mode. For more information, see SET IMPLICIT_TRANSACTIONS (Transact-SQL).
  

• Within MDAC, ITransactionLocal::StartTransaction is basically an equivalent of SET IMPLICIT_TRANSACTIONS ON. This means the transaction will not start until one of the particular set of SQL statements executes. For the list of these statements, see SET IMPLICIT_TRANSACTIONS (Transact-SQL) . Do note Select is one of the statements that will cause the start of a transaction, if it is not in a transaction yet.
  
  
• Within SQLNCLI, ITransactionLocal::StartTransaction is basically an equivalent of BEGIN TRANSACTION, which means an immediate start of a new transaction. But it can not be used to start a nested transaction. If a session has a transaction active, the repeated call of StartTransaction will be ignored.
  
  
• With this difference in mind, the time of a transaction for a stored procedure call using SQLNCLI is possibly slightly longer than it was within MDAC, but the difference is likely negligible.
  
  
• Unless absolutely required, it is not recommended to have your own transaction management stuff in a stored procedure. It will increase unnecessary burden and is prone to human errors. See Rollbacks and Commits in Stored Procedures and Triggers for more info.
  

引用内容

OLE DB does not have a method to set implicit transaction mode specifically.

    * Call the ITransactionLocal::StartTransaction method to start an explicit transaction.

    * When you then call either the ITransaction::Commit or ITransaction::Abort method with fRetaining set to TRUE, OLE DB completes the current transaction and goes into implicit transaction mode. The connection remains in implicit transaction mode as long as you set fRetaining on ITransaction::Commit or ITransaction::Abort to TRUE.

    * Call ITransaction::Commit or ITransaction::Abort with fRetaining set to FALSE to stop implicit transaction mode.

The following is a brief comparison of the various memory allocation methods:

• CoTaskMemAlloc
• GlobalAlloc
• HeapAlloc
• LocalAlloc
• malloc
• new
• VirtualAlloc

Although the GlobalAlloc, LocalAlloc, and HeapAlloc functions ultimately allocate memory from the same heap, each provides a slightly different set of functionality. For example, HeapAlloc can be instructed to raise an exception if memory could not be allocated, a capability not available with LocalAlloc. LocalAlloc supports allocation of handles which permit the underlying memory to be moved by a reallocation without changing the handle value, a capability not available with HeapAlloc.

Starting with 32-bit Windows, GlobalAlloc and LocalAlloc are implemented as wrapper functions that call HeapAlloc using a handle to the process's default heap. Therefore, GlobalAlloc and LocalAlloc have greater overhead than HeapAlloc.

Because the different heap allocators provide distinctive functionality by using different mechanisms, you must free memory with the correct function. For example, memory allocated with HeapAlloc must be freed with HeapFree and not LocalFree or GlobalFree. Memory allocated with GlobalAlloc or LocalAlloc must be queried, validated, and released with the corresponding global or local function.

The VirtualAlloc function allows you to specify additional options for memory allocation. However, its allocations use a page granularity, so using VirtualAlloc can result in higher memory usage.

The malloc function has the disadvantage of being run-time dependent. The new operator has the disadvantage of being compiler dependent and language dependent.

The CoTaskMemAlloc function has the advantage of working well in either C, C++, or Visual Basic. It is also the only way to share memory in a COM-based application, since MIDL uses CoTaskMemAlloc and CoTaskMemFree to marshal memory.

The majority of the tools and equipment you will need for most installations are apparent. The following is a list of useful tools and miscellaneous materials that might also come in handy.

1. A complete set of nut drivers (spin-tights).

2. A set of ratchets and sockets.

3. A pocket compass, for orienting the antenna and setting up the rotor when the compass bearing(s) of the transmitter tower(s) is known.

4. A drill brace with a wide assortment of bits.

5. A good quality leather tool belt.

6. A crimping tool for fastening coaxial connectors.

7. Caulking compound for sealing the holes where transmission line enters the house.

8. Roofing tar (plastic roof cement), for sealing around screws on the roof.

9. Silicone grease for waterproofing coaxial cable connectors.

10. A sledge hammer for driving in ground rods.

11. A level or plumb bob for ensuring that the antenna mast is installed perpendicularly.

12. A map to aid antenna orientation. (Aircraft maps are ideal. Most airports sell them.)

13. A strong step ladder (in addition to extension ladders).

14. A magnetic stud finder.

15.A small, portable TV that operates on both standard house current (117 volts AC) and batteries.

Masts

Most antenna hardware catalogs list a wide variety of mounts and masts. Most however, are variations of a few basic types. By taking into account signal strength and ease of installation, it's not difficult deciding which site, mount, and hardware to use.

A mast (Figure 4-1) is used in every installation. The mast is the vertical tubing that supports the antenna. Conventional masts are available in 5 and 10 foot lengths. Telescoping mast units (Figure 4-2) are available in 20, 30, 40 and 50 foot lengths. Each type is available in various wall thicknesses that provide different degrees of strength and rigidity. Your choice will depend on the height, weight, and size of the antenna being installed and also on wind conditions in the area.

Both conventional and telescoping masts are available in galvanized steel and in high Tensile, acrylic-coated steel. Acrylic-coated masts are preferable because of their greater strength and durability.

MOUNTING SITES AND RELATED PROCEDURES

Attic Installations

An attic installation (Figure 4-3) may work in areas where strong signals are present. In most cases, an attic installation is the easiest, fastest, most economical, and most convenient installation. There are a few conditions however that can prohibit an attic installation. Shallow attics that are obstructed by rafter supports may not accommodate the size antenna required for the installation. Most attics are not large enough to accommodate multi-antenna arrays and rotors. Also, aluminum foil on insulation, aluminum or steel siding, metal gutters at the attic level, and metal lath under older plaster walls all can interfere to some degree with reception.

Fig. 4-3. A typical attic installatIon.

To determine if an attic installation is suitable, take a test antenna, a field-strength meter and a portable TV up into the attic and check the signal level and picture quality. If the signal level is sufficient and there is room enough to properly orient the antenna, assemble the antenna in the attic and attach one end of the transmission line to the antenna terminals. Then prepare the mount for the antenna.

Several roof Type mounting brackets (Figure 4-4) and swivel mounts (Figure 4-5) are adaptable for use in attic installations. The mounting bracket is used to attach the short mast to a rafter or rafter support. The antenna is then mounted on the other end of the mast. The antenna however, must not touch the attic floor. Also, remember that the antenna should be attached to the mast right side up, even though the installation appears to be the reverse of an outside installation.

Fig. 4-4. Fig. 4-5.

Examples of swivel mounts that can be used in attic installations.

An alternative method of mounting the mast is the flatten one end of the mast with a hammer and drill a hole in it through which a nail, screw, or bolt can be inserted for securing the mast to a rafter or rafter support. However, this method requires more time and effort than does the bracket method.

Instead of using a mast, you may suspend the antenna from the inside of the roof with guy wires or nylon rope. But don't let the guy wires touch the antenna elements. They will short out the antenna.

Once you have the antenna mounted or suspended, you are ready to run the transmission line. If at all   possible, keep it indoors. Coaxial cable (Figure 4-6) is  the best transmission line for any antenna installation. It should be used instead of twinlead even in attic installations. Selection and installation of the correct transmission line is described in the chapter beginning on page 15.

Fig. 4-6. CoaxIal cable, the preferred type of TV transmission line.

After you have run the transmission line, use a compass and field-strength meter to orient the antenna toward the signal source(s). Check the picture and sound on all channels before you tighten down the clamp that secures the antenna to the mast.

Some manufacturers make special antennas for attic installations. These antennas however, tend to be omni~directional. This means they intercept signals equally well from all directions. Consequently, they will also pick up interference more readily than a good directional antenna.

Chimney Mounts

Chimney Mounts (Figure 4~7) are used more frequently than other types of mounts, but they often are not the best option. Although they are relatively easy to install, the smoke and gases from a chimney can shorten the life of the antenna and significantly impair its performance.

A chimney installation is practical only if the chimney is sturdy and vertical. Never mount an antenna on a deteriorated chimney. During moderate too high winds an unguyed mast taller than 10 feet can exert enough leverage to break off an unstable chimney.

If you choose a chimney mount, use enough mast to place the antenna above most of the smoke and gases. However, to avoid overstressing the chimney,  do not mount the antenna more than 10 feet above the top of the chimney. If the height of the antenna must exceed 10' to receive satisfactory signals, the mast must be properly guyed. CYhe correct method of  installing guy wires is described in Chapter 7.)

Securing the chimney~mounted antenna and minimizing the stress on the chimney requires the mounting straps to be properly spaced. The top strap should be placed as high up on the chimney as possible. If the chimney has a crown or projecting cap, place the to strap directly under it. The bottom strap should be placed 4 feet below the top strap. If the chimney isn't long enough to permit this, place the bottom strap as far down on the chimney as possible. If the mast must be 10 feet above the chimney top, don't use a chimney mount unless you can space the straps at least 30 inches apart. For masts less than 10 feet above the chimney top, the straps should be spaced no less than 24 inches apart.

Be sure the straps are level, with no kinks or twists. The easiest way to level straps is to line them up along the nearest course of bricks. Straps should be centered on the bricks-not over the mortar joint. Pull each strap tight, line it up so that it's level, and then tighten it just enough to hold it in place.

Before the straps are tightened completely, fasten the mast to the mounting bracket. (1t is assumed that the antenna has already been clamped securely to the mast, and one end of the transmission line has been connected to the antenna terminals.) Align the mast so that it is vertical. Then completely tighten the mounting straps. Next, orient the antenna. Finally, tighten the clamps that hold the mast to the mounting. Be sure the clamps are tight enough to prevent the mast from being rotated by the wind load on the antenna.

Roof Mounts

There are two basic types of roof mounts: a base mount (Figure 4-8) and a tripod (Figure 4-9). Tripods are stronger and more rigid than base mounts, but they are also more expensive. When given a choice, use a tripod.

10 TOOLS, MASTS & HARDWARE REQUIREMENTS

However, if cost savings or limited space require it, a properly guyed base mount will usually work. Unlike a chimney mount, a base mount holds the mast at only one point, the bottom. Consequently, the mast also must be supported by guy wires, regardless of the mast length.

Correct installation of either type of roof mount requires great care and should not be attempted without a helper. Both types of mounts should be secured to the roof with either bolts or lag screws. These should be screwed into only solid wood like a rafter or a truss section. You can locate these with a stud finder.

If you must fasten the mount to the roof in an area where a bolt or screw cannot reach a rafter, send your assistant into the attic with a large square of wood 1-1/2" thick, to act as a backing plate. Have him hold this wood against the entry points of the screws or bolts so that the mount is firmly anchored in both the roof sheathing and the wooden block. This will give the mount needed stability.

When installing a base mount, attach the base plate to the roof in the manner lust described, and place the mast (with antenna, guy ring, and guy wires attached), into the U-bolt that has been fastened loosely to the mount. Do not let the bottom of the mast touch the roof; it may tear a hole in the shingles.

Since a base mount must be guyed, an easy way to raise the mast is to first fasten one of the guy wire screw eyes to the roof peak on the end of the roof opposite the direction in which the antenna is lying. Run the end of the guy wire through the screw eye. Have your assistant slowly raise the mast while you pull the guy wire through the screw eye (figure 4-10). When the mast is vertical, the guy wire you are holding will be approximately the right length for permanent installation. Temporarily secure this guy wire. Install the other guy wires while your helper holds the mast in a vertical position. Check the mast with a level as you tighten and permanently secure each wire. When the mast is vertical and each guy wire has been tightened, orient the antenna and firmly tighten the U-bolt (clamp) on the base mount.

Tripods, as noted earlier, are a stronger, more rigid type of roof mount. The most common tripod mounts are 3, 5, and 10 feet high. The 3 foot tripod is most commonly used. A tripod mount can be installed and leveled before the mast is inserted. It should always be mounted so that the antenna can be folded down along the peak of the roof. This will enable you to lower it more easily should repairs or adjustments become necessary in the future. Even though tripods are very stable, any tripod-mounted mast over 10 feet high should be guyed

Ensure the sturdiness of the tripod by anchoring. To protect the roof, use a pitch pad seal under each tripod leg (Figure 4-11). Coat all lag bolts with roofing tar or other sealant to prevent leaks around them. Roofing tar or silicone should be used liberally around all holes, bolts, screws, nails, and eye screws.

Wall Mounts

Many types of wall mount brackets are available. However, many of them are poorly made and will not withstand more than a moderate wind. Buy only the best quality wall mount brackets (Figure 4-12).

When installing a wall mount, space the brackets as far apart as possible (or practical). Generally, the farther apart you space the brackets, the stronger the installation will be. Be sure the brackets extend out from the wall far enough for the mast to clear the roof eaves. As with roof mounts, screw wall mount brackets only into solid wood, and use caulking or other durable sealant around screws.

Mounting from the Ground

Many times you will not want (or will not be able) to mount an antenna on the roof. One of the best alternatives to roof mounting is mounting from the ground (Figure 4-13). With a firm base support and one or more wall mount brackets, a ground mount installation is exceptionally sturdy and long lasting. A good ground mount may also eliminate the need of guy wires.

Correctly preparing the base of a ground mount is very important. The antenna mast should rest on something more solid and stable than just hare earth. If your installation site is on a solid deck or patio, the base is already prepared for you.

When you have to prepare the base yourself, dig a hold about 2 feet deep at the spot where the mast will contact the ground. Remember that the base hole must line up with the wall bracket(s) so that the mast will be vertical. A plumb line and bob suspended from the roof eave can be used to determine the correct positions of the base hole and wall brackets (Figure4-13). Use bricks or flat stones in the bottom of the hole as a footing to prevent the base of the mast from moving. Concrete can also be used as a footing but you'll have to wait for it to dry before you can put up the mast.

Once the base is prepared, mount a wall bracket at least 10 feet above the ground or as high as possible. Remember, the farther apart the wall brackets are placed, the sturdier the installation (figure 4-13). If there is 5 feet or more left between the first wall bracket and the roof eave, add another wall bracket. Be sure the base hole and the wall brackets line up so that the mast will be vertical. This can be determined easily by suspending a plumb bob and line from the roof eave into the base hole. Also remember that the wall bracket(s) must extend out from the wall far enough so that the mast clears the roof eaves. Be sure the screws of each wall bracket are anchored in solid wood. Screw them into the wall studs.

Firmly clamp the antenna to the upper end of the mast. Insert the mast into the base hole or rest it on the deck or patio. Vertically position the mast by "walking" it up hand over hand. Rest it against the wall bracket(s). Loosely fasten the mast to the wall bracket(s). After determining that the mast is truly perpendicular, tighten the bracket(s) a little more. Next, orient the antenna. After the antenna has been oriented, securely tighten the wall bracket clamps around the mast. Finally, if a base hole is being used, fill in the hole and firmly tamp the soil around the base of the mast.

Telescoping Masts

A telescoping mast (Figure 4-14) is used in installations for which standard 5 or 10 foot lengths of mast stacked together would not be sufficiently strong or rigid. A length of telescoping mast is stronger and more rigid than the same lengths made up of standard mast pieces stacked together. Because of their additional strength, some telescoping masts used with ground mounts can be extended up to 15 feet above the roof line without requiring guy wires. Another advantage of telescoping masts is that they can be easily adjusted to odd heights without having to cut the tubing.

Because telescoping masts are heavy and require firm bottom support, they should not be used with chimney or wall mounts. However, because ground and roof mounts do provide bottom support, telescoping masts can be used with these mounts to provide additional height.

For extra strength when installing large antennas, use a telescoping mast that is one size larger than actually needed. This will permit you to attach the antenna to the mast section immediately below the topmost one. This section is larger and stronger than the topmost section because it is reinforced by the 1-1/4" diameter section that remains inside.

When installing telescoping masts 20 feet or shorter in length, lay the mast on the ground and extend it to the desired length. Prop up the small end on a stable support and attach the antenna and transmission line. Then connect the bottom of the mast to the base mount and walk up the mast to its vertical position. (Use a base mount that will swivel!)

For masts over 20 feet long, securely mount and guy the bottom section first. Then attach guy rings and wires to the rest of the sections. Mount the antenna on the upper section, secure its guy ring and the transmission line. Using a person to hold the guy wires to each anchor point, raise each section one at a time, starting with the top. Tighten the wires after the mast is fully extended.

Vent Pipe Mounting

Vent pipe mounting (Figure 4-16) secures the antenna and mast to the plumbing (gas) vent that comes up through the roof of the house. This type of mounting should be used only for the smallest antennas, and then only when economy absolutely demands it. Vent pipe mounts are not sturdy enough for medium and large antennas. Even a moderate wind or ice load may ruin the installation and damage your customer's property.

Standard vent pipe mounting hardware is available. However, it should be used with great care. Most vent pipes are made of soft materials like copper or orangeburg, which are easily crushed or dented by the stress exerted by the mounting bracket.

Towers

Antennas are mounted on towers (Figure 4-17) when exceptional height (35 feet or more) is required for adequate reception or when an unusually large antenna array must be used. Although they are very sturdy installations if properly installed, towers can be very difficult and dangerous to erect. Tower manufacturers' instructions and specifications usually include a large number of warnings and precautions that must be strictly followed. The best advice that can be given about tower installations before attempting one of your own, is to work with an experienced tower installer on one or more installations. If possible, have an experienced installer assist you with your first tower installation. If you do find yourself involved in a tower installation, be prepared for some heavy work and for the possibility of having to climb well above the height of the average roof.

If you must climb a tower, use an attachable work platform with a safety ring and safety belt. These are available from some tower manufactures. CAUTION: Before climbing any tower, first check the condition of the structure and the guy wires to make sure the installation is safe. Even a newly installed tower may have defects that make it dangerous to climb.

In most cases, a properly guyed 40 or 50 foot telescoping mast can be substituted for a 40 to 50 foot tower installation. It is not only easier and less dangerous to install, it is also significantly less expensive. A detailed discussion about the various types of towers and the procedures for installing each of them would require more space than is available in this manual. The most accurate and helpful sources for such information is the extremely detailed instructions that most tower manufacturers provide with their towers.

FN 公司的一组宣传图

1. Step 1

   Removing the door panel: On a sunny day with mild temperatures, purpose to "fix that sucker", and do it expediently. Sliding glass doors are heavy and awkward, so get some help to remove the panels if you need. Usually, the operable panel of a sliding glass door will come out on the inside of the structure. Sometimes there will be sag in the header above the unit, so it may be necessary to remove the fixed panel from the outside first. Take your small Phillips screw driver and find the roller adjustment holes at the bottom of the door. Insert the tool into the hole and engage the roller screw. Lower the door down as much as possible, by doing forward and back rollers. Now try to lift the door up and swing the bottom into the room to remove the door.

2. Step 2
   
   Removing the old roller

   Removing the rollers: Rest your door on it's edge, and locate the roller adjustment hole. JUST ABOVE that hole is another hole. This is the hole that has a frame/roller screw in it. You must completely remove this screw to remove the old roller.( Be careful not to separate the frame from the glass when doing this procedure)Use the large Phillips screw driver to remove this screw. Pry out the old roller. Secure the door.

3. Step 3
   
   Like for Like

   Go shopping: VERY IMPORTANT; TAKE THE OLD ROLLER TO THE HARDWARE STORE. You must get the identical roller. Examine the new roller and match it in every way to the old. Double check by getting a clerk. BUY TWO ROLLERS. Save money by NOT making a return trip.

4. Step 4
   
   You must thouroughly clean the track

   Installing new rollers: Insert the new roller in the frame you disassembled, and screw it back together. Flip the door over and do the other side. Put the door aside and prepare the sliding glass door frame track.

5. Step 5
   
   You won't believe how much goock is in there!

   Cleaning the track: Lay paper towels on your carpet to protect it. Vacuum and brush out the track all the way across. Now spray the roller track with the WD-40 and let it soak in. Wear safety glasses and use the tooth picks to gouge out all the dead bugs, leaves, dog hair, alligators, and rhinoceroses out of the track. And stay at it until you can see shiny aluminum at the very bottom of the crevice. Use toilet paper or more paper towels to mop up the sludge.

6. Step 6

   Re-installing the door: Bring over your door and put it back in. First insert it in at the top, and then swing the bottom into place and down onto the track. Use the small Phillips screw driver to adjust the new rollers. Slide the door over to the closed position, but leave a 1/4" gap top to bottom. Adjust the rollers so the gap is parallel to the frame vertically. Congratulations, your door slides very nicely now, and you can say, "I did it myself"! Thanks to Ken Swanson

7. Step 7
   
   Removing the lock screws

   Optional Extraction: Sometimes lodged doors have to be removed from the outside. Even to the point of grinding off the screen guide. To do the panel extraction, remove the top and bottom fixed center screws on the fixed panel.(see picture)Pull the fixed panel out of the side frame, lift the panel up, and swing the bottom out and away, and take out the fixed panel. Now the operable panel will swing outside and be removed.

Good Video:  roof vent:  www.youtube.com/watch eave vent:  www.youtube.com/watch VENTILATION BASICS Proper attic ventilation is an important part of a healthy home–both for the structure and its occupants. This document explains how attic ventilation protects a home from moisture and how to install vents that will keep your home in good condition. There are a wide variety of sources of moisture in a home, from the building materials themselves to normal everyday activities. Cooking, bathing and washing clothes all release gallons of water vapor into the air, for example. That vapor isn't a problem inside the average home because the temperature inside the home is warmer than outside for much of the year. Warm air holds more moisture–in the form of water vapor–than cool air. The problem is that vapor gradually works its way out of the living area and into the structure. As warm, moist air cools, the vapor begins to condense into water droplets. If that happens inside an unfinished attic, for example, it can get insulation and framing materials wet. That not only reduces the value of your insulation but can cause mold, mildew and rot. During the summer, when the outside temperature is typically much higher than the inside temperature, attic ventilation serves a different purpose. An unfinished attic builds up a tremendous amount of heat, and if that heated air has no place to escape, it can make the inside of the house much warmer or cause an air conditioning system to work much harder to cool the house. Building codes specify the minimum amount of attic ventilation needed in a new home to prevent winter moisture buildup, but your summer needs are much greater. Also, older homes were often built with inadequate attic ventilation–at least by today's standards–and may need to be retrofitted with proper attic ventilation. A good attic ventilation system is designed for summer needs. It includes two types of vents: intake vents are placed along the soffit to allow fresh air into the attic, and exhaust vents are installed in the upper third of the roof to allow attic air to escape. The object is to create a continuous "wash" of air along the underside of the roof sheathing. The rule of thumb in the summer is that you should provide enough ventilation to completely change the air in your attic every six minutes. There are three common types of intake vents: Gable vents are triangular vents installed in the gable wall just below the peak of the roof. As a rule, gable vents are the least effective type of vent, because air circulates only near the gables and does not wash the entire roof. Static vents, also known as roof line or eyebrow vents, consist of a sheet metal cylinder with a flashing collar and a metal hood to keep rain out. They are installed in rows along the face of the roof by cutting holes in the roof, nailing the flashing collars to the roof sheathing and shingling around the vents. Their effectiveness depends on how many are installed; probably their greatest disadvantage is that like any roof penetration, they may leak. Soffit vents are made usually with a screen to keep insects out and of an aluminum panel with louvers punched into the face to allow air flow. They may be 4" or 8" wide and 14" or 22" long, so they'll fit between 16" and 24" on center rafters. They are installed simply by cutting rectangular holes in the soffit and screwing the vent over the hole. A continuous soffit vent is of similar construction, 4" wide and 96" long. It is installed by cutting a long slot in the soffit and screwing the vent over the hole. Circular vents range from 1" to 8" in diameter. They are installed by drilling holes in the soffit and pressing the vent into the hole. Exhaust vents fall into two basic categories. Static vents simply allow air to escape while power ventilators actively suck air out of the attic. Within each category there are a number of types: Ridge vents are installed along the peak of the roof and replace the ridge singles. Power Ventilators are turbine vents that consist of a turbine mounted on a sheet metal cylinder. They are installed like roof line vents along the face of the roof. When the wind blows, it spins the turbine, which in turn draws air up out of the attic. Their effectiveness, naturally, depends on whether the wind is blowing or not. Fan-driven ventilators are powered by electricity and usually controlled by a thermostat in the attic. They are very effective, but since they are motor-driven, the extra cost of running them partially offsets the energy they conserve. Most builders agree that a ridge vent system is the most effective as well as the most cost-effective. The number of vents you'll need depends on the type and size of the vents. Vents are rated according to their square inches of "free vent area" (FVA)–in other words, the amount of open space in the vent. You can't just measure the size of the vent to find the FVA because the open space is reduced by louvers and by the screen mesh that covers the opening. Most manufacturers provide both FVA ratings and ventilation recommendations for their products. In order to estimate, you'll need to know the total square footage of your attic and possibly the slope of your roof. To find the square footage of your attic, multiply the width of your house by the length. Roof slope is expressed as a ratio–for example, a 5:12 slope means that the roof rises 5" vertically for every 12" of horizontal distance. To find the approximate slope of your roof, go into the attic and measure the vertical distance from the peak of the attic ceiling to the ceiling joists in feet (e.g., a 75" measurement would be 6-1/4'). Multiply that measurement by 24, then divide the result by the width of your house (also in feet). The answer is the first half of your slope ratio. For example, say your house is 30' wide, and the peak-to-ceiling-joist measurement is 75" (6-1/4'): 6-1/4 x 24 = 150 150 divided by 30 = 5 Your slope is approximately 5:12

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INSTALLING ATTIC VENTS Installing attic vents in an existing roof is a relatively simple job that most do-it-yourselfers can handle. Remember to follow basic safety procedures when working on the roof: Wear loose clothing and rubber-soled shoes with good ankle support. Only work on the roof in dry, calm weather. Be alert for slippery or loose shingles or rotten decking that you might put a foot through. Avoid power lines and TV antennas. Keep children and pets away from the area so they aren't hurt if something falls off the roof. Your extension ladder should be angled so the base is away from the wall a distance equal to 1/4 of the ladder's length plus the width of the soffit. Intake Vents–To install intake vents, set your circular saw blade to a depth about 1/8" greater than the thickness of the soffit (soffit materials are usually 1/4" thick). Lay out the location of the vent between the rafters, then cut the hole with the circular saw. Screw the vent to the soffit, covering the hole. If you have fiberglass blanket insulation in your attic, make sure the blankets are positioned so they cover the top of the exterior wall but still allow at least a 1" space between the top of the insulation and the underside of the roof sheathing. Otherwise, the insulation will block the air flow and your soffit vents will be useless. If you have loose fill insulation in your attic, you'll need to install baffles in each rafter cavity that contains a soffit vent to keep the air space clear. Roof Line/Turbine Vents–To install roof line or turbine vents, first locate the vent between two rafters. Use a utility knife to cut away the shingles and felt paper, then use a saber saw to cut a hole in the roof the same size as the throat of the vent. Butter the inside of the vent base with plastic roof cement, then slip the base into position over the hole. The top of the flashing should be slipped under the shingles above the hole and lap over them below the hole. Nail the base in place with 1-1/2" galvanized roofing nails and cover the nail heads with roof cement. If you're installing a turbine vent, slip the turbine onto the base and level it. Fasten the turbine in place with sheet metal screws. Gable Vent–To install a gable vent, cut away the siding and sheathing with a circular saw. Be careful not to cut too deeply into the gable studs. Caulk the rim of the gable vent, then set it over the hole and fasten it in place with screws. Ridge Vent–To install a ridge vent, first remove the ridge shingles as specified by the vent manufacturer–usually to within 6" of the end of the ridge or a foot from a chimney or roof intersection. Cut away the felt paper with a utility knife and pull out all staples and roofing nails. Snap a chalk line along the roof sheathing on either side of the ridge; the manufacturer's instructions will tell you how far from the peak the line should be. Set your circular saw blade to a depth slightly thicker than the sheathing, then cut away the sheathing along the line. Remove the cut pieces of sheathing and any nails that remain. Install the ridge vent over the peak. You can start the vent at the end of the roof or the beginning of the slot, whichever the manufacturer recommends. Different ridge vent systems use different methods of making the vent weather-tight; follow the manufacturer's instructions.

Click on drawing above to view animation.

TOOL AND MATERIAL CHECKLIST

• Intake Vents
• Steel Tape Measure
• Utility Knife
• Screwdriver
• Saber Saw
• Putty Knife
• Pencil
• Screws
• Ladder
• Exhaust Vents
• Level
• Hammer
• Circular Saw
• Plastic Roof Cement
• Chalk Line
• Nails
• Eye Protection

How to replace Flyscreen Mesh

This handyman hint explains how to replace the mesh in a flyscreen door.

To replace the mesh in your flyscreen doors and windows, start by measuring the height then the width of the flyscreen you wish to replace.  You will need a minimum of 75mm to 100mm (3 to 4 inches) extra all round.  Write these measurements down and take them to your local hardware store.  Meshing is sold in widths of 900mm (about 3 feet) and 1200mm (about 4 feet).

When you get home again, remove the screen by lifting and then twisting one corner out, then slide the screen out completely.  Remove the rubber tubing that holds the mesh into the frame by prying up at the join,  pull gently until it comes free. Now you can remove the old mesh and dispose of in the rubbish bin.

 Lay the new mesh over the screen door and then push the rubber tubing into the slot at one corner, on the longest side of your screen.  You can purchase a wheel at the hardware store for this job. Alternatively, you can use a small piece of timber dowel or the handle of an old dinner knife with a very blunt blade.  Holding it at an angle to the mesh and apply downward pressure.  

Continue down one side until finished.   I find it best to then do the opposite side to the first.  Don’t pull the mesh too tight, as the mesh is tightened as it is forced into the groove by the tubing.  Watch that the mesh is kept straight, that is, the weave in the mesh is parallel to the screen. 

Then you can proceed to the top edge and finally the bottom edge; again do not pull the mesh too tight.  Let the tubing do this for you.  Now trim off the excess mesh very CAREFULLY, using a sharp knife. 

When you have finished put the screen back into place one corner first then wiggle the screen into place. 

Hey, that wasn’t so bad was it?  Remember that practice makes perfect.

DIY guide of installing a Netafim Smart Drip System 点击下载此文件  , a bit too simple.

Designing an Irrigation System  seems pretty good.

SATA in comparison to other buses (sourced from wiki):

Name	Raw bandwidth (Mbit/s)	Transfer speed (MB/s)	Max. cable length (m)	Power provided	Devices per Channel
eSATA	3,000	300	2 with eSATA HBA (1 with passive adapter)	No[29]	1 (15 with port multiplier)
SATA 300	3,000	300	1	No	1 (15 with port multiplier)
SATA 150	1,500	150	1	No	1 per line
PATA 133	1,064	133	0.46 (18 in)	No	2
SAS 300	3,000	300	8	No	1 (16k with expanders)
SAS 150	1,500	150	8	No	1 (16k with expanders)
FireWire 3200	3,144	393	100; alternate cables available for >100 m	15 W, 12–25 V	63 (with hub)
FireWire 800	786	98.25	100[30]	15 W, 12–25 V	63 (with hub)
FireWire 400	393	49.13	4.5[30][31]	15 W, 12–25 V	63 (with hub)
USB 3.0*	4,800	600	3[32]	4.5 W, 5 V	127 (with hub)[32]
USB 2.0	480	60	5[33]	2.5 W, 5 V	127 (with hub)
USB 1.0	12	1.5	3	Yes
Ultra-320 SCSI	2,560	320	12	No	15 (plus the HBA)
Fibre Channel over optic fiber	10,520	2,000	2–50,000	No	126 (16,777,216 with switches)
Fibre Channel over copper cable	4,000	400	12	No	126 (16,777,216 with switches)
InfiniBand 12× Quad-rate	120,000	12,000	5 (copper)[34][35] <10,000 (fiber)	No	1 with point to point Many with switched fabric

Obviously, according to the chart, the transfer rate of SATA has go beyond the capability of the network since the introduction of SATA I. This fact makes the use of SATA II (not to mention SATA III) hard drive on a networked file server moo point if most of the usage of those disks are for sharing over the network.

or am I missing anything?

Telephone Plugs and Sockets for Australia

>> Telephone Plugs and Sockets for Australia

Introduction

There are currently three different types of line termination connectors used in Australia for telephone and data use.

Definitions

This series is what is commonly called the "old Australian type" and has been installed in Australia, primarily by Telstra, for approximately 30 years. There is a huge installed base of this type of connector.

This type of connector has been installed in Australia for a period of approximately 5 years, originally developed in the USA by Bell Labs (the same Bell that invented the telephone) by engineers Charles Krumreich and Edwin Hardesty, it has now become the most widely used telephone connector in the world. You will see it is used in the connection port for most telephones, faxes etc.

This connector is quite often misnamed, however in Australia it is commonly called the RJ12. In the USA it is called RJ11 or RJ14, depending on wiring configuration. RJ12 can used to connect a maximum of 6 wires.

RJ stands for "registered jack" - not Ross Jackson, our MD, as many people think !

This connector is an evolution of the RJ12, having a wider body to allow 8 wires to be connected. Telstra and Optus, amongst others, are installing this connector into homes and offices across Australia.

It cannot be plugged into a RJ12 socket, however, a RJ12 can be plugged into a RJ45 socket, using a reducing sleeve.

Australian 600 Series Details

How to install

Loosen screw "A" and remove the cover.

Remove screw "B" and withdraw the plug.

Replace screw "B" and make sure it sits flush. If the screw is too long replace it.

Replace cover and tighten screw "A"

RJ12 and RJ45 Series Details

Any of the series of jacks, described in the

, Title 47,

, used to provide

to the public

RJ (registered jacks, sometimes described as RJ-XX) are a series of telephone connection interfaces (receptacle and plug) that are registered with the U.S. Federal Communications Commission (FCC). They derive from interfaces that were part of AT&T's Universal Service order Codes (USOC) and were adopted as part of FCC regulations. The term jack in the USA sometimes means both receptacle and plug and sometimes just the receptacle, although in Australia it means socket. A plug is male and a socket is female.

This plug and socket combination is not used for wall termination. It is the very small connectors used to connect your telephone to the handset..

As mentioned above, the most common telephone connector in the world is the RJ-12 jack, which can have six conductors but usually is implemented with four or sometimes two. The RJ-12 jack is likely to be a socket that your household or office phones are plugged into. In turn, these sockets connect to the outside longer wires known as twisted pair, which run to the telephone companies switch or to a private branch exchange (PABX). The four wires are usually characterised as a red and green pair and a black and white pair. The red and green pair typically carry voice or data. On an outside phone company connection, the black and white pair may be used for Iow-voltage signals such as phone lights. On a PBX system, they may be used for other kinds of signalling.Your computer modem is usually connected to a RJ-12 jack.

6 position / 4 contact modular plugs
Plug positions	USOC RJ14	USOC RJ11
1
2	white/orange
3	blue/white	blue/white
4	white/blue	white/blue
5	orange/white
6

6 position / 6 contact modular plugs
Plug positions	USOC RJ25
1	white/green
2	white/orange
3	blue/white
4	white/blue
5	orange/white
6	green/white

As mentioned above, Telstra and Optus are now installing this type of socket in homes. The RJ-45 is a single-line jack for digital transmission over ordinary phone wire, either untwisted or twisted. The interface has eight pins or positions. For connecting a modem, printer, or a data PABX at a data rate up to 19.2Kbps, you can use untwisted wire. For faster transmissions in which you're connecting to an Ethernet 10/100/1000BaseT network, you need to use twisted pair wire. (Untwisted is usually a flat wire like common household phone extension wire. Twisted is often round.).

RJ45 is also called Category 5 or "Cat 5" in Australia, which refers to a specification for data transmission. Cat 5 or RJ45 are physically compatible, and both are suitable for telephones or modems depending on data rate requirements.

8 position modular plugs
Plug positions	T568A	T568B
1	white/green	white/orange
2	green	orange
3	white/orange	white/green
4	blue	blue
5	white/blue	white/blue
6	orange	green
7	white/brown	white/brown
8	brown	brown

A new home for chooks so they don't fly the coop.

DIAGRAM点击下载此文件

Fresh are the best! And they taste even better when they've been laid by happy chooks in your own backyard. This A-frame chicken coop can be moved about your yard quite easily and will keep your hens feeling clucky, safe and right at home.

A chicken coop that can be lifted and moved around the garden is a great way to fertilise the yard while the chickens enjoy a feast of bugs, pests and weeds. The coop has everything that opens and shuts to lock away your chooks at night plus give you easy access to collect eggs.

Chooks are great pets to keep around the home: they eat food scraps, produce fantastic natural fertiliser, keep pests down in your garden and lay eggs.

Kids also love feeding them, hunting for their eggs and playing with them. This simple, moveable chicken coop is a great way to house your birds and is large enough to accommodate up to six full-sized chooks or eight bantams.

Hens need a home, especially during the night to keep them safe from foxes and domestic animals, which will kill your birds if they're not locked away. This coop has wire on the floor to stop predators from digging their way into it. However, during the day, chickens are much happier to scratch around the backyard looking for worms, insects, weeds and whatever else they can find to eat. Just make sure the backyard is enclosed and the flight feathers on the hens are clipped.

But before you rush out and buy half-a-dozen hens or build a chook house, check your local council's regulations and requirements for keeping poultry. Some discourage keeping chooks, others ban roosters. It's also a good idea to chat with your neighbours before proceeding. Whatever the result, keeping a rooster will probably be out of the question because early morning wake-up calls do not make for happy neighbours. Besides, you probably want to eat the eggs, not breed chickens.

You'll need
(See diagram)

A Frame uprights (8) 70 x 35 x 1220mmTreated pine

B Narrow ties (4) 70 x 22 x 635mm Treated pine decking 81 Wide ties (2) 90 x 22 x 635mm Treated pine decking

C End panels (2) 635 x 628 x 4mm Bracing ply

D Gussets (2) 310 x 263 x 4mm Bracing ply

E Ridge 90 x 22 x 1800mm Treated pine decking

F Bottom plates (2) 90 x 45 x 1800mm Treated pine

G Side rails (4) 70 x 22 x 422mm Treated pine decking

H Back panel 1800 x 616 x 4mm Bracing ply

I Handles (2) 90 x 45 x 2400mm Treated pine

J Box slats (12) 90 x 22 x 330mm Treated pine decking

K Back panel support 70 x 22 x 1000mm Treated pine decking

L Bottom end rails (2) 90 x 45 x 1100mm Treated pine

M Small door stiles (2) 42 x 18 x 515mm LOSP pine N Small door rails (2) 42 x 18 x 296mm LOSP pine

O Small door panel 515 x 380 x 4mm Bracing ply

P Large door stiles (2) 42 x 18 x 515mm LOSP pine

Q Large door rails (2) 42 x 18 x 946mm LOSP pine

R Large door mullion 42 x 18 x 431 mm LOSP pine

S Large door panel 1030 x 515 x 4mm Bracing ply

T Bottom stiles (2) 42 x 18 x 500mm LOSP pine

U Bottom door rail (2) 42 x 18 x 296mm LOSP pine

V Hinge blocks (6) 40 x 19 x 90mm LOSP pine

W Small end rails (2) 70 x45x481mmTreated pine

X Perch (not shown) 90 x 22 x 1115mmTreated pine decking

You'll also need:
10m x 1200mm of galvanised 25 x 25 x 1.25mm welded mesh; galvanised staples or U nails; 2 x T-hinges; 6 x 50mm strap hinges; 4 latches; feeder, water dispenser, paint

STEP 1
Cut 1 end of each of the main framing uprights (A) at an angle of 65 degrees. To do this, use a protractor to set a sliding bevel to exactly 65 degrees. Mark the angle. Measure 1192mm along the timber, mark the same 65 degrees angle with the bevel and cut to length. Measure 25mm across the top bevel of each upright, square a line down from this point to form a right angle and then cut off the triangular section.

Chickens are safe and fun pets, and are great for teaching children responsibility.

STEP 2
Screw together pairs of uprights to form A-frames. Cut both ends of the narrow and wide ties (B, B1) at an angle of 65 degrees. Mark 499mm from the bottom of each upright and screw 2 narrow ties to 2 of the frames and the 2 wide ties to the other 2 frames with the bottom edge of the ties on the marks. Screw the remaining narrow ties to the back of the 2 frames with the wide ties.

STEP 3

Use the A-frames as a template to mark out the end panels (C) and cut with a panel saw. Unscrew the narrow ties, and nail on the plywood with flat head nails. Replace the ties again and nail panel into the tie. Similarly, cut the gussets (D) for the internal frames and nail on.

STEP 4
Screw the top ridge (E) to the end frames, with the back edge 5mm proud of the top of the frame and overhanging on the door side. The plywood end panels face inward. Measure 400mm from the end and screw on the intermediate A-frames with the plywood gussets facing towards the ends and the inside edge of the frames on the mark. Screw the outer A-frames to the bottom plates (F), then measure 400mm from ends to locate the intermediate frames.

STEP 5

Fix the side rails (G) to the A-frames, screwing them at the same height as the ties in the A-frame. Nail the back panel (H) to the frame, then add the two handles (I) to either side.

STEP 6

Turn the unit on its side and add the brooding box slats (J), screwing them on from the underside and spacing them equally between the sides. The gaps between the slats allow air to circulate. While tipped over, add the back panel support batten (K) under the ridge and nail the back panel to it. Cut the bottom rails (L) with a 65 degree angle at each end and screw to the bottom plates and end A-frames.

STEP 7

To retrieve the eggs, you'll need doors. Screw the small door stiles (M) to the rails (N) using simple butt joints and screws, then nail on the small door panel (O. If you do not have short nails simply nip the ends off 30mm galvanised flat-head nails. Repeat for the other small door and the large door (F Q, R, S). The bottom door (T, U) is made in the same way but covered with chicken wire not plywood. Fit the doors with the strap hinges, using hinge blocks (V) on the upper doors to give them clearance. When everything fits, remove the hinges. Cut the small end rails (W) and screw in place. Add a perch (X) screwed to the underside of the box slats.

STEP 8
Paint all the woodwork with two coats of exterior acrylic paint. We chose Dulux Pesto for the frame and Salvia for the panels. When dry, refit the doors with the hinges.

STEP 9
Cut the mesh to size with snips to suit each section and with enough extra all round to allow the wire to be stapled to the frame. Use galvanised staples or U nails to hold the wire mesh in place. When starting them off, try holding the staples with long-nosed pliers rather than your fingers.

STEP 10

At the sides remove the side rails and fix the wire underneath before refitting the rails over the top. Fold and nail the wire to the underside of the handles. At the ends remove the bottom rail and nail the wire to the inside edge of the bottom rail, then screw the bottom rail back in place and nail the wire to the rest of the frame. Fit basic catches to the doors to secure them at night.

Now you have a chookhouse, you want to know what chickens to buy, where to buy them and how to keep them.

For eggs within a week or so then purchase point-of-lay pullets that are about six months old. Avoid buying chicks - they may grow up to be roosters. Pullets cost about $20 each and lay between 180 and 250 eggs a year.

When you get your hens home, keep them in the coop for a week to get them used to their new home. Then let them range, but make sure your garden is bait free.

In the hens' brooding boxes, lay carpet offcuts, pile side down, and top with straw. This will keep your chooks comfortable while nesting and the eggs safe from smashing. Put a fake plastic or china egg in the nest to encourage the chooks to lay.

Feed the chickens with commercial layer pellets, which have all the vitamins and minerals hens need, and put the pellets in a bird feeder hung away from brooding boxes and perches. An adult hen will eat about 1 kg of food each week, including household food waste. Sprinkle eggshells over your scraps to give the chooks the calcium they need for strong eggs.

Install an automatic waterer away from the feeder.

Check the coop daily, and keep the water, food, perches and straw clean to avoid disease and parasites.

For MORE information on keeping hens, visit www.users.on.net/~greggles/

To buy chooks and pullets, check out Poultry Farmers and Dealers in the Yellow Pages.

Want something bigger? Click here for an even larger chicken house!

• Exposure is automatic but your Exposure Compensation controls still work.  This is Big. Using Exposure Compensation, you can influence the camera’s opinion on exposure within a range of four stops, over and under inclusive.
• Exposure Lock is available and must be used.  Once you and the camera agree on an exposure using the above-mentioned Exposure Compensation dial, lock that sucker down.  The last thing you want is for the camera to drastically change exposure just because something bright or dark suddenly enters frame.  Trust me it absolutely will if you don’t use the Exposure Lock feature.
• There are a couple of ways to do an autofocus approach but they are awkward and frustrating.  Buck up and learn to manually focus the way the big kids do.
• Sound can and will be recorded through an internal mic but don’t expect much quality.  The camera’s onboard mic will hear you best of all.  It will also hear the Image Stabilizer and any other camera noises.  Better sound can be acquired by using an external microphone that can be attached through the “audio in” plug.  Consider something like the Sennheiser MKE400 if sound is important and you don’t mind coughing up the cake.  I think it’s best to concentrate on picture during your earliest explorations…
• Yes! Image Stabilization does work in video mode and is always activated unless you manually turn it off on the lens.  This is a great help for handheld work and makes the 24-105mm f4 IS a really useful lens on the 5D Mark II.
• Still captures may be in RAW or jpeg format and either sRGB or Adobe RGB according to you choice.  The video color space is sRGB and no Raw equivalent is available.  Too bad; I hope this becomes available in future generations.  As it is, watch your exposures and stay tuned to proper white balance.
• Picture Styles apply!  This is also Big.  By custom tuning your Picture Styles, you can have great control over how the camera records color sharpness, and contrast.  B&W and Sepia modes are readily available and that just too cool for words…

Once it’s installed, the new firmware makes it pretty easy to actually perform your exposure adjustments. The same dials and controls you’d use to manually adjust exposure when taking still images are used during video recording, so operation is pretty intuitive for anyone with familiarity with the camera.

Make sure your Live View Function Setting is on Stills + Movie, and your Screen Settings are on Movie Display

Here’s the procedure:

1. Live View/Movie function settings: Be sure your LV (Live View) settings are set to “Stills + Movie”. Then, press the SET button as indicated on the Menu screen to drill one more step down, and set your Screen Settings to “Movie Display”.
   
   This last point is vital: If your Screen Settings are anywhere but “Movie Display” you will not be able to manually adjust exposure.


2. Turn the Mode Dial on top of the camera to “M” (Manual exposure mode), as you would to manually adjust exposure during a still image.


3. Press the Live View button (to the left of the viewfinder) to activate Live View. This is always a requirement before movie shooting is possible, and this firmware update doesn’t change that.



Press the INFO button on the rear of the camera to see the analog metering scale as an exposure reference in Movie Mode
4. If you want to see the camera’s analog metering scale to use as a guide for setting manual exposure, press the INFO button until it appears at the bottom of the LCD monitor. Now, as you make exposure adjustments, you’ll see the indicator on the scale change as lighting and settings change. Of course, users are also free to use a separate hand-held meter or other methods to determine proper shutter speeds, apertures, and ISO settings.


5. Turn the Main Dial (near the shutter button) to adjust shutter speeds, over a range of 1/30th thru 1/4000th of a second. Turn the rear Quick Control Dial to adjust the aperture setting, through the entire range available on the lens you’re currently using. And press the ISO button (top of camera) and turn the Main Dial to vary ISO, or set Automatic ISO operation.

As noted above, users can set manual shutter speeds during video recording anywhere from 1/30th of a second thru 1/4000th. Speeds can be set in 1/3-step increments, or via Custom Function I-1-1, in 1/2-step increments. Shutter speeds are set by turning the Main Dial, preferably before video recording begins, although they can be set and changed during actual recording.

Use the Main Dial to control the shutter speed during manual exposure in Movie Mode

The effects will take place virtually immediately, but it’s possible that the sound of clicking through the dial’s settings will be picked-up in your video footage through the camera's built-in micorphone (of course, that can be avoided by using an optional external microphone plugged into the camera's audio input, or using a seperate portable sound recording device).

Apertures are adjusted by simply turning the rear Quick Control Dial, once the EOS 5D Mark II has been set-up for Manual exposure shooting during video recording. Be sure the camera’s main On-Off switch is raised to its upper-most position, which activates the Quick Control Dial — if you’re just set to “ON”,

Use the Quick Control Dial to control the aperture settings during manual exposure in Movie Mode

the camera itself is active and turned on, but you won’t be able to adjust the Quick Control Dial for any exposure-based settings.

You can manually select any ISO from 100 - 6,400 (12,800/"H1" if the ISO Expansion Custom Function is active). To change the ISO, press the ISO button on top of the camera, and use the Main Dial to select the sensitivity you want