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Mean, mode, median, and quantiles

Posted by on 13/ 11/ 15

Подпись:Подпись: (2.30)

Mean, mode, median, and quantiles Mean, mode, median, and quantiles Подпись: [1 — Fx (x)] dx

The central tendency of a continuous random variable X is commonly repre­sented by its expectation, which is the first-order moment about the origin:

This expectation is also known as the mean of a random variable. It can be seen easily that the mean of a random variable is the first-order L-moment Л1. Geometrically, the mean or expectation of a random variable is the location of the centroid of the PDF or PMF. The second and third integrations in Eq. (2.30) indicate that the mean of a random variable is the shaded area shown in Fig. 2.11.

The following two operational properties of the expectation are useful:

1. The expectation of the sum of several random variables (regardless of their dependence) equals the sum of the expectation of the individual random

Fx(x)

Mean, mode, median, and quantiles

F...

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The Parts of a House

Posted by on 13/ 11/ 15

When vou decide to build a house, there’s a

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whole new vocabulary you have to master. Every part of a house has a name and, ns with most endeavors, learning the lingc will take you a long way toward getting the job done. There are plenty of terms that intuitively make sense, such as header, footing, cladding, brace, and sheathing. In other cases, you’ll find that some parts have several names. The illustra­tion on the facing page, combined with the definitions on the following pages, will give you a good basic working vocabulary that we’ll build on in later chapters.

Sill or sole plates

These are generally pressure-treated (PT) 2x4s or 2x6s that are bolted to the concrete founda­tion and support the floor joists.

The Parts of a House

Posts, girders, and beams

Posts are vertical supports for horizont...

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Economics

Posted by on 13/ 11/ 15

"Economical” means doing only what is necessary to getting a job done. Anything more would be wasteful and contrary to the inherent simplicity of good design. An economical home affords what is essential to the comfort of its occupants without the added burden of unused space. Excess and economy are mutually exclusive. We can have exorbitance, or we can have the serenity that a sensibly-scaled home affords, but we cannot have both. Like anything else that is not essential to our happiness, extra space just gets in the way. It requires maintenance and heating, and ultimately demands that we exchange a portion of life for the money needed to pay for these extras.

For most Americans, big houses have come to symbolize the good life; but, all symbolism aside, the life these places actually fo...

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Water in the Vadose Zone

Posted by on 13/ 11/ 15

The groundwater table is defined as the locus of points at atmospheric pressure. Below the water table the pore water pressure is positive and in a hydrostatic state, while the pore water pressure increases linearly with depth. Above the groundwater table, in the vadose zone, water only remains in the pores due to capillary action. The water pressure is then negative or less than the atmospheric pressure and capillary pressures, known as matric suctions, exist. Large matric suctions correspond to large negative water phase pressures and soils under such conditions usually have low wa­ter saturations. Furthermore, both the water content and therefore the permeability are nonlinear functions of these capillary conditions.

In unsaturated soils, pore spaces are filled with both water and air...

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CROSS-SECTION DESIGN

Posted by on 13/ 11/ 15

This article provides information to assist the designer in determining lane widths, pavement cross slopes, shoulder widths, interchange cross-section elements, medians, curbs, pedestrian facilities, and grading and side slopes. The number of lanes for a given roadway facility is best determined using principles and procedures contained in the “Highway Capacity Manual” (Ref. 10). This manual analyzes roadways to determine an appropriate “level of service,” by which a letter value (A through F) is assigned depending on the volume of traffic and other geometric features. Table 2.20 provides a design guide for level of service for various facilities by functional classification and terrain or locale. The table includes a brief description of the characteristics of each level of service...

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The Affordable Housing Demonstration

Posted by on 13/ 11/ 15

In the Affordable Housing Demonstrations, actual housing developments were built in 27 cities and communities in 24 states throughout the United States, with local public officials and the designated builder cooperating to reduce the cost of the completed homes. All the developments built in the program were subject to the ultimate test of the marketplace when the homes were completed and sold. Costs and savings in each demonstration project were carefully monitored, and each project was described and analyzed in a Case Study prepared by the NAHB National Research Center and published by HUD. A list of the projects appears in Appendix

The central theme of the demonstrations was that builders and local officials can, together, identify ways to reduce the cost of housing and to modify or int...

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The Khanouqa dam and the Semiramis canal

Posted by on 13/ 11/ 15

At the Khanouqa gap on the Euphrates some 80 km upstream of its confluence with the Khabur, are the remains of hydraulic works.[69] This includes a rock weir, built of loose natural basalt blocks, damming the Euphrates so as to provide all-season water to a canal whose offtake is immediately upstream of the dam (Figure 2.13). The left-bank canal is called the canal of Semiramis[70] in the writings of the Greek traveler Isidore of Charax, dating from the first century AD:

“There is found the canal of Semiramis; the Euphrates is blocked by rocks so that, in its nar­rowed state, it floods the plain; but in the summer boats run aground there.” [71]

Подпись: Figure 2.13 The weir at the Khanouqa pass and the canal of Semiramis (after Calvet and Geyer, 1992).
The Khanouqa dam and the Semiramis canal

Remnants of the canal are partially visible in the vicinity of Khabur, along about 80 km...

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Foundation wall insulation

Posted by on 13/ 11/ 15

Foundation insulation isn’t used in mild cli­mates. But in areas with frigid winter months, it can improve interior comfort and save on heating costs. Even though it’s not required by code in many areas, it’s definitely worth install­ing wherever prolonged freezing temperatures are expected. You can install insulation on the inside or outside of a crawl-space or basement wall. Exterior insulation, in the form of rigid foam boards, is glued to the foundation walls before backfilling. Where they’re exposed above the finished grade on the exterior, insulation boards must be protected with siding material or stucco. It’s important to remember that any type of foundation insulation can provide a hid­den passageway for termites and other insects to enter the house...

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A Mishandled Spill

Posted by on 13/ 11/ 15

Early in his career as an environmental consultant, John Banta received a frantic call from a woman with chemical sensitivities who was in the process of having a home built. Theclient had painstakingly detailed plans and specifications with the help of John and her architect. The project had proceeded virtually without problems, and was entering the final interior painting and sealing process when a worker for the subcontracting painter accidentally kicked over a bucket of nontoxic paint, spilling it on the unfinished floor. The worker ran to his truck and grabbed a can of mineral spirits, which he used to clean up the spill. The solvent soaked into the floor and the fumes filled the house. John’s cli­ent became distraught because her new house was making herfeel sick.

Discussion

In spit...

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Metal Connectors

Posted by on 13/ 11/ 15

If wood is the universal building stock, metal is the universal connector. Nails of many types as well as screws and bolts are discussed in this sec­tion. Specialty plates that reinforce structural members are also described. Later in this chapter is a review of construction adhesives, which, some say, are destined to supplant metal connectors.

NAILS

As they’re driven in, nail points wedge apart wood fibers. The ensuing pressure of the fibers on the nail shank creates friction, which holds the joint together. Nails also transmit shear loads between the building elements they join. Where nails join major structural elements, such as

Подпись: Specialty nails. 1, Simplex nail for roofing underlayment and thin foam insulation; 2, copper flashing nails; 3, galvanized roofing nails; 4, gasketed nail for metal roofing and some skylight flashing; 5, duplex nails; 6,finish nails (the middle one is vinyl coated); 7,furring nails for stucco wire; 8, ring-shank nail; 9,stainless-steel nail color matched to wood siding; 10,joist-hanger nails (Teco® nails); 11, case-hardened masonry nail. Nail Sizes

1

2

112

4

2

6

212

8

3

10

314

12

312

16

4

20

412

30

5

40

6

60

rafters and ...

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