Blog Archives

Filler Content

Posted by admin on 15/ 11/ 15

In the majority of worldwide regulations for SMA, the content of particles passing through the smallest sieve (0.075 or 0.063 mm ) generally ranges between 8% to 13% (m/m). However, adopting extreme quantities may be a risky business—that is, 8% can lead to building too little mastic. On the other hand, a large quantity of filler (e. g., approximately 13%) may generate too high a content of mastic, making it susceptible to overstiffening or increasing the risk of forming fat spots.

It has been discussed in Chapter 3 that the optimum relationship between quantities of filler and binder is best illustrated by the filler-to-binder ratio (by weight or volume). This means that each quantity of filler corresponds to a certain optimum amount of binder...

The qanats in Egypt under the Achaemenid Empire

Posted by admin on 15/ 11/ 15

In Chapter 2 we described the invention of the qanat in Urartu and its development in Persia. After the conquest of Egypt by Cambyse, qanats are introduced in Egypt to irrigate the oases as well as the mountainous zones situated along communication routes (the wadi Hammamat, between Thebes and the ports of the Red Sea). Traces of three qanats constructed by order of Darius I (about 500 BC) have been found in the oasis of Kharga, some 300 km to the northwest of Asswan.[127] These qanats are as deep as 75 m, with a gallery several kilometers long and a rather flat slope compared to the usual practice, only about 0.5 per thousand.

Irrigation in the land of the Queen of Sheba Irrigated oases at the threshold of the desert

To the south of the Arabian peninsula, the mountains of Yemen rise to ...

Content of the Fine Aggregate Fraction

Posted by admin on 15/ 11/ 15

In classic SMA composition and in regulations introduced all over the world, the total content of grains smaller than 2 mm has generally been in the range of 15-30% (m/m). When we add the typical filler content (8-13%), we receive up to 22% from the sand fraction (0.063/2.0 mm). But when designing the content of fine aggregate in SMA, one should remember the increase in the content of fine particles during compaction due to crushing and wearing of the coarse particles.

Is the sand fraction desired in a mix? Looking at the shape of an example SMA gradation, we can imagine a mix designer adding all the permitted quantity of filler (i. e., approximately 13% [m/m]) instead of 0.063/2.0 material. This example is illustrated in Figure 6.13...

A thousand years of traffic on the Necho canal

Posted by admin on 15/ 11/ 15

So what is the actual path of this ancient canal? We know it fairly well, since the remains observed in the twentieth century substantially agree with the descriptions of Greek and Roman travelers. The canal issues from the eastern branch of the Nile, follows the southern edges of the wadi Tumilat valley, passes by Tell er-Retaba and Tell el – Maskhouta (Tjekou), rejoins lake Timsah, then flows directly south toward the bitter lakes and the Gulf of Suez. Let us listen to a continuation of the account of Herodotus: “It takes four days to travel along it, and its width is such that two triremes could be rowed in it side by side. It is fed by the waters of the Nile, and begins a little above Bubastis (Tell Basta) by Pithon (Tell el-Maskhouta), an Arabian town. It ends in the Red Sea...

RIGID PAVEMENT DESIGN PROCEDURE

Posted by admin on 15/ 11/ 15

Подпись: FIGURE 3.10 Load-response curve used to determine resilient modulus. (From M. Thompson, “Factors Affecting the Resilient Modulus of Soils and Granular Materials," Proceedings of Workshop on Resilient Modulus Testing, Oregon State University, Corvallis, 1989, with permission)

Determine the drainage coefficient for the pavement.

4. Select the design serviceability loss.

5. Estimate the total number of 18-kip (80-kN) equivalent single-axle loads for the design period.

6. Select a level of reliability and the overall standard deviation.

7. Determine slab thickness and steel reinforcement.

Determine Effective Subgrade Modulus. The first step in designing the thickness of a rigid pavement is the determination of the effective modulus of subgrade reaction. The effective modulus (or composite modulus) is the modulus of subgrade reaction after correction for use of subbase, seasonal variation in subgrade and subbase strength, rigid foundation within 10 ft (3 m) of the surface, and loss of support. Figure 3...

The great accomplishments of Egypt in the first millennium BC: from the last pharaohs to the Persians

Posted by admin on 15/ 11/ 15

Who dug the first “Suez Canal”?

Egypt had a long tradition of maritime commerce with countries on the shores of the Red Sea (in particular with the country of Punt, situated approximately east of Sudan and north of Eritrea). The port of Mersa Gawasis was founded in about 1900 BC under Amenemhat II (Middle Empire), somewhat below the 27th parallel (therefore a bit to the north of Thebes). Merchandise is carried by land to or from Thebes through arid valleys, typified by the wadi Hammamat.

One can therefore readily appreciate the interest in a direct maritime link between the Nile and the Red Sea. Such a link was in fact realized though the valley of the wadi Tumilat with an east-west orientation...

RISER DRAWINGS

Posted by admin on 15/ 11/ 15

Riser drawings are used when figuring out drainage systems, just as they are used with vent systems. I want to give you some sample riser diagrams to look over. The drawings will show you what your drawings might look like. Drains are drawn with solid lines, while vents are indicated by broken lines.

RISER DRAWINGS

FIGURE 4.26 ■ Wet venting top floor single bath group. (Courtesy of Standard Plumbing Code)

RISER DRAWINGS

FIGURE 4.27 ■ Wet venting top floor double bath back to back. (Courtesy of Standard Plumbing Code)

SHOWERS

M N

RISER DRAWINGS

FIGURE 4.28 ■ Wet venting lower floors on multistory buildings. (Courtesy of Standard Plumbing Code)

RELIEF VENTS A & В MAY CONNECT TO MAIN—„„

VENT ABOVE FIXTURES ON FLOOR ABOVE

-T—I

OTHER USEFUL POWER TOOLS

Posted by admin on 15/ 11/ 15

Although not often used by frame carpenters, two other power tools worth mentioning are routers and sanders. These tools are typically used for finish work, like preparing a bookcase for stain or paint, which makes them more suitable for trim and finish carpenters.

Routers

Routers are classified according to the largest-diameter bit shank that the collet (or chuck) can handle. Common sizes are Уд in., 3/s in., and У2 in. The most powerful routers have З-plus HP motors and can make big cuts through heavy stock in a single pass.

Equipped with the right bit, the router can be adapted to a number of carpentry jobs. You can cut grooves and notches, round over edges, trim materials (like plastic laminate), and make moldings with a router...

Retrofit Results

Posted by admin on 15/ 11/ 15

construction Basement: Ceiling sprayed with open-cell spray polyurethane foam (adds thickness and R-value)

Walls: 2×4 construction filled with cellulose; 4 in. of foilfaced polyisocyanurate foam outside of sheathing for a total of R-39

Roof: 6 in. of polyisocyanurate insulation installed above the existing roof sheathing, topped with a layer of plywood; 8 in. of open-cell spray polyurethane foam (Icynene) installed between the existing rafters for a total of R-59

Windows: Double-pane (U-0.33) windows by Pella®

Location:

Arlington, Mass. Size: 3,000 sq. ft. (duplex)

Renovation cost: $47 per sq. ft.; $140,000 total

Mechanicals

Heating: Oil-fired steam boiler in each unit

Water: Main boiler in unit 1; on-demand gas water heater in unit 2

Ventilation: Heat-recovery ventilators (one for ...

Multivariate normal distributions

Posted by admin on 15/ 11/ 15

A bivariate normal distribution has a PDF defined as

for k = 1 and 2. As can be seen, the two random variables having a bivariate normal PDF are, individually, normal random variables. It should be pointed out that given two normal marginal PDFs, one can construct a bivariate PDF that is not in the form of a bivariate normal as defined by Eq. (2.108).

According to Eq. (2.17), the conditional normal PDF of X11 x2 can be obtained as

(2.109)
>■;

.H.

0.1

Multivariate normal distributions Figure 2.26 Three-dimensional plots of bivariate standard normal probability density functions. (After Johnson and Kotz, 1976.)