Blog Archives

HIGH MAST LIGHTING

Posted by on 23/ 11/ 15

The value of high mast lighting has been highly controversial since its introduction in the early 1960s. Proponents suggested that high mast lighting offered considerable enhancements to visibility. Opponents, on the other hand, argued that high mast lighting was expensive to build, offered little improvement to visibility, and often resulted in light trespass and light pollution. By the early 1980s, new data became available which suggested the superiority of high mast light over conventional systems. The reasons cited were

• An improved visual field negating the “tunnel effect” caused by a limited lateral dimension when using conventional mounting heights...

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Joes Rocket Research Landing Pad – A Photo Essay

Posted by on 23/ 11/ 15

Joe Zinni, like Larry Schuth and Mark Powers, is a former cordwood masonry student at Earthwood. He and his wife Glenna found a 1.25-acre piece building lot they liked in Tenino, Washington, an area where local sawmills are cutting lots of very large timbers. Joe described a friend’s sawmill to me: “Rob, picture a giant Wood Mizer mill, except with a band saw blade eight inches wide and a quarter inch thick, and a throat about six feet across. You wouldn’t believe the size of the timbers they run through there.” In a letter, Joe listed some timbers he has lying around. One is a 16- by 32-inch by 40-foot (40.6- by 81.3-centimeter by 12.2- meter) beam. Another is 13- by 40-inch by 36-feet long. He’s got a half dozen beams measuring 12- by 26-inches by 40 feet. The mind boggles...

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Parallel systems

Posted by on 23/ 11/ 15

For a parallel system, the entire system would perform satisfactorily if any one or more of its components or modes of operation is functioning satisfactorily; the entire system would fail only if all its components or modes of operation fail.

In the framework of load-resistance interference for different modes of oper­ation, the failure probability of a parallel system, according to Eq. (7.9), is

Parallel systems

M

П (Wm < 0)

m=1

 

Pf, sys = P

 

P

 

П (Zm < m=1

 

вт)

 

Ф(-в I Rz)

 

(7.43)

 

Parallel systems

which can be computed as the multivariate normal probability discussed in Sec. 2.7.2. The bounds for system failure probability also can be computed if the exact value of Pf, sys is not required...

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Laying Out a Tub Back Wall

Posted by on 23/ 11/ 15

image823Almost all tubs slope slightly, so use a spirit level to locate the lowest point. From that lowest point, measure up the height of one tile, plus ‘I in., and mark the wall. Draw a level control line through that mark, as shown in the illustration at right, and extend that level line to all three tub walls. Use a story pole to see if you’ll need to cut tiles. If so, lay out tiles so cuts are symmetrical on both ends of the back wall. Draw a plumb line on each end of the wall to indicate where the cut tiles will begin. Finally, through a tile joint along the level control line, draw a plumb control line that roughly bisects the backwall. Start tiling where control lines meet.

TILING A TUB SURROUND

1...

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TYPES OF LUMINAIRES

Posted by on 23/ 11/ 15

Conventional roadway lighting has been the cobra head luminaire mounted on a support arm and positioned at the edge of the roadway or, in some cases, out over the roadway. The base of the pole when a breakaway device is present should be a minimum of 15 ft (4570 mm) from the travelway, but 20 ft (6100 mm) is preferred on roadway sections with­out a curb. The travelway is defined as being a continuous traffic lane and does not include an acceleration or deceleration lane merging with a through lane. When a curb is present, the pole with its breakaway device is preferred to be 10 ft (3050 mm) from the face of the curb. If this is not possible, the pole should be closer than 2 ft (610 mm)...

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RAFTER DIES ON ROOF

Posted by on 23/ 11/ 15

 

Framing

 

ROOFiNG

SHEATHiNG

 

RAFTER DIES ON ROOF

SUPPORT TO RAKE.

 

CUT ON FASCiA iS MADE AT PiTCH OF ROOF & ABOVE LEVEL OF ROOFING; FASciA IS SuppORTED ву RAFTERS &

sheathing.

 

SHEATHiNG

 

Elevation

 

——- ROOFING

 

SHEATHING

FASCIA

  RAFTER DIES ON ROOF

FASCIA DIES ON ROOF

 

RAFTER DIES ON ROOFRAFTER DIES ON ROOFRAFTER DIES ON ROOF

ROOF SHEATHiNG

 

END RAFTER

 

common

RAFTER

 

EDGE FLASHiNG

 

VERGE RAFTER OR TRiM BOARD CONTiNUOUS TO FASCiA

 

WALL

sheathing

 

furring

continuous

behind

VERGE RAFTER SEE 150A

 

FURRiNG ALLOWS VERGE RAFTER OR TRiM BOARD TO ACT AS DRiP.

 

double top plate

 

VERGE RAFTER OR TRiM BOARD

 

SiDiNG TRiMMED TO cONTiNuOuS FuRRiNG

 

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MOSAIC TILE   After you’ve set paper-backed sheets of mosaic tile in adhesive, the paper will start to soften, allowing you to reposition the tiles slightly. To move a row of tiles, place the straight edge of a trowel against them, as shown, and tap the trowel lightly with a hammer handle.   Countertop Front and Back Edges   Use a grout float to seat mosaic tile in the thinset adhesive. Be sure to don knee pads that are comfortable enough to wear all the time.   Flash the front edge of a counter, as shown, to prevent the exposed edges of the plywood from wicking moisture from the thinset adhesives and then swelling. Because the back edges of the countertops are also vulnerable to water damage, caulk and flash them, too.   through those marks, perpendicular to the con­trol line, to the back of the counter. L-SHAPED COUNTER On an L-shaped counter you have, in effect, two counters at right angles to each other, so you will need two control lines, perpendicular to each other, running along the front edge of each section. Any other layout considerations are subordinate to these two control lines, for they determine how the two oncoming tile fields will align.   STRAIGHT COUNTER, WITH SINK To tile a straight counter with a sink, the layout is much the same as a counter without a sink, except that here, your main concern is making symmetrical tile cuts (if necessary) on either side of the sink. If you need to cut tiles, move the story pole side to side until the tile joints are equidistant on each side of the sink’s rough open­ing. Then transfer those two marks to the control line. Finally, use a framing square to run lines &nbsp

Posted by on 23/ 11/ 15

Use your framing square and a straightedge to establish control lines and to keep the tiles aligned once you’ve turned the corner. After set­ting V-cap trim tiles, start tiling where the two control lines intersect. As with straight counters, put full tiles along the front of the counters and work back, relegating cut tiles to the very back, to be covered by the backsplash. If you use the same tile for the backsplash, continue the tile joints up the wall so that the backsplash and counter joints line up.

Tub Surround

Never assume tub walls are plumb. Always check them with a 4-ft. level. If walls aren’t plumb with­in % in. in 8 ft., correct them with a mortar bed or reframe them. Otherwise, tile joints from adja­cent walls won’t align...

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Reliability of Simple Systems

Posted by on 23/ 11/ 15

In this section the reliability of some simple systems will be discussed. In the framework of time-to-failure analysis, availability of such systems will be pre­sented. Information such as this is essential to serve as the building blocks for determination of reliability or availability of more complex systems.

7.3.1 Series systems

A series system requires that all its components or modes of operation perform satisfactorily to ensure a satisfactory operation of the entire system. In the context of load-resistance interference, the failure event associated with a mode of operation is

Fm = {Wm < 0} form = 1, 2,…, M

in which Wm is the random performance variable associated with the mth mode of operation. Referring to Chap...

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Checking Reference

Posted by on 23/ 11/ 15

To check using four reference lines, measure the two diagonals, then write down the measurements on the footprint you used for measuring the dimensions. If the corner points are set correctly, then the diagonals will be the same length. If the reference dry lines are square, then the diagonals will be the same length. (See “Start-up" example.)

If you have only two reference lines to work with, you’ll need to use a triangle to help you check for square. The two reference lines will be “square" with each other if they create a right angle (90°). You can use a 3-4-5 triangle or the Pythagorean

theorem to determine whether the two reference lines create a 90° angle...

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Bounds for system reliability

Posted by on 23/ 11/ 15

Despite the system under consideration being a series or parallel system, the evaluation of system reliability or failure probability involves probabilities of union or intersection of multiple events. Without losing generality, the deriva­tion of the bounds for P (A1U A2 U—U AM) and P (A1 n A2 П—П AM) are given below.

For example, consider P(A1 U A2 U-U AM). When Am = Fm, the probability is for the failure probability of a series system, whereas when Am = Fm, the probability is for the reliability of a parallel system. The bounds of system failure probability, that is, can be defined as follows:

Pf ,sys – Pf, sys – Pf, sys (7.11a)

with p f sys and p f, sys being the lower and upper bounds of system failure prob­ability, respectively...

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