Blog Archives

The Impact of Mixture Parameters

Posted by on 22/ 11/ 15

Basically, the type of aggregate mix, the type and content of binder, and the amount of air voids (Va), voids in mineral aggregate (VMA), voids filled with binder (VFB) are taken into account when analyzing the resistance to deformation of an asphalt mixture course. The development of rutting is a fairly complex process depending on, among other things, the relationships among the three aforementioned factors. Hence the resistance to deformation depends on the shear strength of an asphalt mix (Kandhal et al., 1998), which is the result of binder and aggregate (aggregate blend) interactions.

With mixtures like SMA, it would seem to be a justified statement that with such a strong aggregate structure, the role of the binder should be substantially reduced...

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GUIDELINES FOR MULTIPLE – SIGN-SUPPORT CONSTRUCTION

Posted by on 22/ 11/ 15

The following guidelines should be followed for multiple-sign-support construction:

• Multimount sign supports are designed to function properly when more than one support is struck by an errant vehicle. There will be occasions, however, where only one support will be impacted. When this occurs, it is necessary that the sign panel be properly fastened and have sufficient rigidity so that the post(s) that are not impacted will support the sign panel, preventing intrusion into the vehicle.

• The hinge should be located at least 7 ft (2100 mm) above the ground to prevent the upper section of the support from penetrating the windshield.

• No portion of the primary sign, additional signs, or bracing should be attached to the supports below the hinges...

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Advection — Diffusion

Posted by on 22/ 11/ 15

Transport of pollutant or of heat in porous media is governed by a combination of advection and diffusion (Chapter 6, Section 6.3.1). The advection phenomenon is related to the transport (noted as a flow f ) of any substance by a fluid flow,

described by the fluid’s velocity, f df/:

fad. = Cf (11.11)

The substance concentration, C, is generally supposed to be small enough not to influence the fluid flow. In porous media, due to the tortuosity of the pore network, and due to the friction, advection is always associated with a diffusion characterised by the diffusion-dispersion tensor, D. Therefore, the total flux of substance is:

Lad. = Cf – iD9’C <1U2>

Balance equations and storage equations may be written in a similar way to the one for diffusion problems Eqs. 11.6, 11.8 and 11.10.

Comp...

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Water resources for Persia and the silk road

Posted by on 22/ 11/ 15

The traveler coming from Taklamakan or India enroute for the Roman or Arab worlds, whether he crosses the Kush or the high passes of Pamir that lead to Bactria, encounters the vast arid zone of the Persian plateau (or Khorassan). The plateau’s sparse and unre­liable water resources were exploited by means of several irrigated oases during the

Bronze Age. Then much larger irrigated zones were developed beginning with the peri­od of the Achaeminde Persians. This development was based on the mining of ground­water through qanats. The earliest evidence of these projects is the account of the his­torian Polybius, who describes an expedition led by the Seleucid king Antiochus III against the Parthians in 210 BC...

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Green Framing Feeling

Posted by on 22/ 11/ 15

Green framing feeling sounds a little subjective, but that’s because it has to be. For example, you are out on the job site framing, and the questions is whether to throw a small cut off of 2 X 6 into the trash or try to find a place to use it in your building process. Your decision is not only based on the cost of that piece of cut-off, but also the ease of just trashing it and the effect on the environment by using a new piece. Not an easy call to make, but you will have to make decisions like that all the time. If you choose the extra effort to conserve material, you will get a good green framing feeling.

Advanced Framing

A more tangible aspect of green framing is advanced framing...

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Diffusion

Posted by on 22/ 11/ 15

Thermal conduction exchanges (Chapter 4) in solids and diffusion of contaminants (Chapter 6) are modelled by similar diffusion equations.

The balance equation is written:

дг/г + Q — S (11.6)

where / represents a flux of fluid or heat, Q represents a sink term and S represents the storage of fluid or of heat. When modelling a diffusion problem with the finite element method, the most often used formulation is based on fluid pore pressure, u, or on temperature, T.

Then the Darcy’s law for fluid flow in porous media gives the fluid flux (this equation has been presented in a slightly different form in Chapter 1 (Eq. 1.2) and in Chapter 2, Eqs. 2.15 and 2.16):

/і — — (дги + дг pgz) (11.7)

д

with the intrinsic permeability K (possibly depending on the saturation degree), the d...

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FASTENING SIGN BLANKS ON MULTIPLE-SIGN-SUPPORT SYSTEMS

Posted by on 22/ 11/ 15

The sign blank and its mounting hardware become a structural component of the sign assembly upon impact. Slip base and frangible coupler designs of multiple-sign-support systems require the sign panel hardware, and the upright signposts, to provide the

TABLE 7.15 Bolt-Tightening Specifications for Slip Base Design

a.

Specifications

in U. S. Customary units

Post size,

Bolt

Clamping

Torque,

in X lb/ft

size, in

force, lb

ftlb

S3 X 5.7

K

920-1380

7-11

S4 X 7.7

К

920-1380

7-11

W6 X 8.5

5-8

1740-2660

17-19

W6 X 12

5-8

1740-2660

17-19

W6 X 15.5

5-8

1740-2660

17-19

W8 X 17

5-8

1740-2660

17-19

W8 X 20

5-8

2400-3600

17-19

W10 X 21

5-8

2400-3600

31-46

W10 X 25

5-8 or 5-8

2400-3600
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Hydraulic works in medieval India

Posted by on 22/ 11/ 15

Dams for control of river flow and for irrigation are also built on the Indian subcontinent itself. One of the oldest of the important dams in India is an earthen structure built about 150 AD on the Kaviri River in the southern region of Cola. This dam, 330 m long and 18m wide, is rebuilt in the 11th century. River traffic is important along the great rivers of central India – the Ganges and the Indus. Later on, the Hindu civilization takes refuge in the south of India when the Turks occupy the north of the country. From the 9th to the 12th century, in particular, the maritime empire of the Cola unifies all the south of India, even temporarily occupying Ceylon. Numerous dams are built, probably under the influence of the earlier developments in Ceylon...

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Allow for ventilation space when insulating attics and ceilings

Posted by on 22/ 11/ 15

With insulation, the only time you can have too much of a good thing is when the ceiling or attic insulation blocks the roof’s ventilation. As shown in the illustration on p. 205, there must be a clear pathway for air to move from the eaves to the ridge.

In the house shown here, we nailed OSB baffles in place on the walls between the roof trusses to prevent the attic insulation (blown-in cellulose) from spilling into the eaves and cover­ing soffit vents. When a house has a cathedral ceiling, there is no attic space to fill with insula­tion. Instead, fiberglass batts must be installed between the rafters. Be especially careful not to block the ventilation space between the rafters...

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TARLETON

Posted by on 22/ 11/ 15

The Tarleton has the same over­all footprint and exterior appear­ance as the Lusby. The primary differences inside are that the Tar – leton’s kitchen is a bit bigger and that there is no bedroom down­stairs. The loft space is the same. 1

НІ

Square feet: 130

House width: 8’

House length: 19’

Road Height: 13’-5”

Dry Weight: 5400 lbs

Porch: 3’x 7%’

Great Room: 6’ x 6%’ Kitchen: 31/2’ x 61/2’

Bathroom: 3’x 6’

Ceiling height: 6’ 6710’ 6” Loft height: 3’ 8”

-sizes are approximate

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