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General View of System Reliability Computation

Posted by on 22/ 11/ 15
Подпись: Figure 7.2 Schematic diagram of a parallel system.
General View of System Reliability Computation

As mentioned previously, the reliability of a system depends on the component reliabilities and interactions and configurations of components. Consequently, computation of system reliability requires knowing what constitutes the system being in a failed or satisfactory state. Such knowledge is essential for system classification and dictates the methodology to be used for system reliability determination.

General View of System Reliability Computation

Figure 7.3 Procedure for infrastructural engineering system reliability.

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STEP 2 Install the Ceiling Panels

Posted by on 22/ 11/ 15

It’s best to drywall the ceiling before you do the walls. This way, the top edges of the wall panels can butt up against the ceiling panels, supporting them along the edges. The long

edges of ceiling panels run perpendicular to the joists or joist chords. In bedrooms and other small rooms, you’ll probably be able to cover the full length of the ceiling with 12-ft. panels. If the ceiling is more that 12 ft. long, stagger the end joints where the panels butt together, just as you do on floor and roof sheathing panels. Try not to have a drywall joint land on an electrical or heat outlet, because this makes it harder to tape and hide the seam.

Measuring and cutting drywall panels

If you watch professional drywall installers measure and cut panels, you’U be impressed with the speed and accu...

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Scheme Accuracy

Posted by on 22/ 11/ 15

The theoretical analysis of a time integration scheme accuracy and stability is generally based on a simplified problem (Zienkiewicz et al., 1988). Let us con­sider diffusion phenomena restricted to the linear case. Introducing the discre – tised field (Eq. 11.15) into the constitutive equations gives Darcy law (Eq. 11.7) (neglecting here the gravity term for the sake of simplicity and using the more gen­eral pressure p in place of u) in the following form:

fi = – K dtp = – K (dtNL )pL (11.32)

p p

Similarly the storage law (linear case) can be re-written:

S = rp = rNLpL (11.33)

where r is a storage parameter (cf. Eq. 11.8). Neglecting source terms, the weak form of the balance equation, Eq. 11.21, then produces:

j [SSp – ft dt (8p)]dV

V

/

к

– Nl pl diNK 8 pKdV = 0

p

VV

Considering...

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Reliability of Systems

Posted by on 22/ 11/ 15

7.1 Introduction

Most systems involve many subsystems and components whose performances affect the performance of the system as a whole. The reliability of the entire system is affected not only by the reliability of individual subsystems and components but also by the interactions and configurations of the subsystems and components. Many engineering systems involve multiple failure paths or modes; that is, there are several potential paths and modes of failure in which the occurrence, either individually or in combination, would constitute system failure. As mentioned in Sec. 1...

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Definitions and Test Methods

Posted by on 22/ 11/ 15

The notion of compactability has been repeatedly used in this text, especially in Chapter 10. Compactability (i. e., susceptibility to compaction) can be defined as the ability of an asphalt mixture to change density under the influence of compactive effort; or to put it another way, compactability is the material feature determined by the amount of energy necessary for the compaction of a given mass into the smallest volume (Schabow, 2005). Resistance to compaction is the reverse of compactability. Generally, it means that compactable mixtures (with a low resistance to compaction) do not need a lot of compactive effort.

Resistance to compaction is connected with features of a mixture, such as the gradation of the aggregate mix and the aggregate properties, which include the following:

• C...

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SIZES AND TYPES OF DRYWALL

Posted by on 22/ 11/ 15

Drywall is made by sandwiching a gypsum core between two sheets of paper. The “good" side of the panel is faced with smooth, white paper that takes paint easily. The “bad" side is darker in color, with a rough, porous paper surface. Panels (also called sheets) of drywall are packaged in pairs; to open the package, simply pull off the strips of paper that extend along each end.

The standard width for drywall panels is 48 in. For houses that have 9 ft. ceilings, use drywall sheets that are 4 ft. 6 in. wide. Different lengths are available, but for affordable hous­ing the most commonly used lengths are 8 ft. and 12 ft. The most common thickness for drywall is V2 in. However, 5/8-in.- thick panels are often used on ceilings where the joists are spaced 2 ft. o. c...

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Arab Science and Hydraulic Machinery Hydrodynamics and Marvelous Machines

Posted by on 22/ 11/ 15

We have seen that a political climate favorable to intellectual activity evolved under the Abbassides – and this climate coincided with important needs for hydraulic develop­ment. Scientists and often engineers made use of all the fruits of Greek and Hellenistic science in parallel with major construction projects. They produce precise mechanisms, water clocks (clepsydres) and other marvelous machines following the tradition of the ancient scholars of Alexandria, Philon, Ctesibios, and Heron.

Three brothers – Muhammad, Ahmad, and al-Hasan Banu Musa, known to the caliph al-Mamun around 820, wrote numerous treatises on these mechanisms. Of par­ticular note is the Kital al-Hiyal, Book of Ingenious Mechanisms, written in Baghdad about 850...

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Test Results

Posted by on 22/ 11/ 15

A fairly comprehensive range of methods and test parameters can be found in publi­cations on SMA fatigue properties. For example, in Australian research (Stephenson and Bullen, 2002) the strain-controlled mode was used to conduct a four-point bend­ing beam test at 20°C, with continuous haversine loading at a frequency of 10 Hz and a range of strain levels from 100 to 1000 pe. On the grounds of the test results, it can be stated that the fatigue limit of an SMA mixture is higher than a comparative specimen of AC.

12.1 WORKABILITY

The concept of workability has been used for determining a series of mixture prop­erties significant at the time of placement of a pavement...

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Contractors Sell Large Systems because They Fear Complaints

Posted by on 22/ 11/ 15

In defense of the people selling and install­ing large air-conditioning systems, they do so for a reason. Profit plays a part, sure: If you install a bigger system, you make more money. More important, though, contrac­tors fear complaints about their systems’ inability to maintain set temperatures in extremely hot conditions. Using a rule-of-

thumb measurement or some other method, the contractor sizes the system larger. If 3 tons is good, 4 is better, right? Besides, "Maybe Manual J sizing isn’t quite big enough," a contractor might say, or "Here, it gets hotter than that."

A recent study, however, puts these fears to rest...

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Resampling Techniques

Posted by on 22/ 11/ 15

Note that the Monte Carlo simulation described in preceding sections is con­ducted under the condition that the probability distribution and the associated population parameters are known for the random variables involved in the system. The observed data are not used directly in the simulation. In many statistical estimation problems, the statistics of interest often are expressed as functions of random observations, that is,

© = ©( X1, X 2,…, Xn) (6.110)

The statistics © could be estimators of unknown population parameters of in­terest. For example, consider that random observations Xs are the annual max­imum floods...

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