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Criteria and Constraints for Pollution Mitigation

Posted by on 23/ 11/ 15

12.3.1 Consideration of Site Sensitivity and Vulnerability

Analysis of the natural conditions of a road course is usually the second stage in the planning of the road construction where the first stage is defined by legislation and socio-economic factors. The protection level of the water and water environment from road influences depends on factors that are connected with:

i) road and traffic characteristics;

ii) natural sensitivity and vulnerability of the existing environment; and

iii) presence of the areas with special public interest (e. g. public water supply re­sources, special areas for vineyards, locations of rare flora or fauna, Natura 2000, etc.).

For example, the protection of the water environment on a low permeable clay stra­tum will need to be totally different from the pro...

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Summary and Conclusions

Posted by on 23/ 11/ 15

Hwang et al. (1981) presented a review of literature related to system reliability evaluation techniques for small to large complex systems. A large system was defined as one that has more than 10 components and a moderate system as one which has more than 6 components and less than 10. Complex systems were defined as ones that could not be reduced to a series-parallel system. Hwang et al. concluded that for a large, complex system, computer programs should be used that provide the minimum cut sets and calculate the minimal cut approx­imation to system reliability. Minimal paths can be generated from minimum cuts. Based on minimum cut sets, reliability approximations then can be ob­tained for large, complex networks. Hwang et al...

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Work Begins

Posted by on 23/ 11/ 15

Подпись: Fig. 5.7:1 notched the east side eight-by-eight girt to fit it up against the stub of the original four-by-eight rafter. I chiseled and scraped deteriorated wood, back to sound material, and doused the area with a water-sealing product. Note the use of Sill Sear between the girt and the top mortar joint of the cordwood wall.image115Former Earthwood student Doug Kerr visited for a week to help out on the early stages of the project. He wanted to learn timber framing, but didn’t want to wait for the book. Doug arrived in the evening, and the next morning we tore up the entire front sitting deck, and all of the original four-by­eight deck joists. The post-and-beam frame of the original solar room’s south wall was still in excellent condition.

Подпись:Подпись:image116The east and west walls of the lower story were 16-inch cordwood walls, and, for insulation and architectural purposes, we wanted to maintain that same width and style in the new addition. I chose to install new cedar eight-by-eight girts where the old deteriorated doubled four-by-eights had been removed...

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EARTH PRESSURE CONSIDERATIONS AND DETERMINATION

Posted by on 23/ 11/ 15

Once a proper selection has been made of feasible wall types that satisfy the necessary constraints, design consists of determining the earth pressure against the back of the wall and then proportioning the wall so that it will be structurally sufficient to satisfy a number of traditional checks. These checks include stability against sliding and overturning, and foundation bearing pressure limits. Clearly, satisfying the traditional checks would be of no value if the entire structure were to move because of some condition not related to any of these three checks. Therefore, it is also important that the designer be assured that the wall is globally stable—i. e., that no deep-seated slide or slip surface exists.

An important and essential part of the design of retaining walls consists of...

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GENERAL CUTTING

Posted by on 23/ 11/ 15

Tight trim joints require accurate layouts, sharp saws, and consistent methods.

Recuts are a fact of life. If you’re filling and painting trim, slight gaps are acceptable. But if you’re using a clear finish, joints must be tight. Before you start cutting trim, always check the accuracy of power-saw miter-stop settings by cut­ting a few joints from scrap. Then cut stock a hair long so that you can recut joints till they’re right.

Cut lines consistently. It doesn’t matter whether your sawblade cuts through the middle of a cut line or just past it. What matters is that your method is consistent. For example, moving the width of a saw kerf to one side of the line or the

Подпись:other can make the difference between tight and open joints...

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Fault-tree analysis

Posted by on 23/ 11/ 15

Conceptually, fault-tree analysis, unlike event-tree analysis, is a backward anal­ysis that begins with a system failure and traces backward, searching for pos­sible causes of the failure. Fault-tree analysis was initiated at Bell Telephone Laboratories and Boeing Aircraft Company (Barlow et al., 1975). Since then, it has been used for evaluating the reliability of many different engineering systems. In hydrosystems engineering designs, fault-tree analysis has been ap­plied to evaluate the risk and reliability of earth dams, as shown in Fig. 7.14 (Cheng, 1982), underground water control systems (Bogardi et al., 1987), and water-retaining structures including dikes and sluice gates (Vrijling, 1987, 1993). Figure 7.15 shows a fault tree for the failure of a culvert as another example.

A f...

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The first large transport canals of the 5th century BC

Posted by on 23/ 11/ 15

Irrigation and drainage make it possible to develop cultivated land, as we have seen. In addition, the transport of bulk matter (especially grains) relies mainly on canals. Therefore it is typical to find dense networks of irrigation canals branching out from main transport canals during the major kingdoms. The following text of Sima Qian gives us an idea of the scale:

“Sometimes later (up to this point the text speaks of the works of Yu the Great) the Hong Canal was constructed, leading off from the lower reaches of the Yellow River at Xingyang, passing through the states of Song, Zheng, Chen, Cai, Cao, and Wey, and joining up with the Ji, Ru, Huai, and Si rivers...

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Evaluation Factors

Posted by on 23/ 11/ 15

Evaluation factors that can be used on selected conceptual wall designs include the following:

• Constructibility

• Maintenance

• Schedule

• Aesthetics (appearance)

• Environment

• Durability or proven experience

• Available standard designs

• Cost

The sum of all weight factors should be 100 points. To simplify the selection process, minor factor(s) may be removed from the rating matrix. This is readily achieved by assigning the same score for minor factors on all the selected feasible wall types.

8.1.1 Notes on Using the Worksheets (Figs. 8.2, 8.3, and 8.4)

1. Factors that can be evaluated in percentage of wall height

A. Base dimension of spread footing

B. Embedded depth of wall element into firm ground

FIGURE 8.5 Requirements for wall cost study...

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WORKING WITH MDF

Posted by on 23/ 11/ 15

If you want a cost-effective, easily worked material for plain-profile trim, MDF (medium-density fiberboard) is hard to beat. And you can add visual interest by installing cove, bullnose, quarter – round or other simple molding along MDF’s plain edges.

Advantages. MDF cuts and shapes beautifully. For smooth edge cuts, use a 60-tooth 10-in. blade. Because it has no grain, MDF crosscuts and rips equally well, and its edges can be routed as well, although most MDF trim is simply butt joined. (No need for biscuits to hold the joints closed.) Use a pneumatic nailer to attach it; MDF won’t split. Sand it with 150-grit sandpaper and prime with an oil-based primer (latex roughens the surface). However, MDF does have quirks you need to work around.

Disadvantages. MDF is heavy (a 14-in...

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Mitigating Pollution from Roads

Posted by on 23/ 11/ 15

The level of pollution originating form roads depends on several factors that can also have an influence on pollution mitigation and prevention. These factors can be divided into two general groups:

• natural factors that depend on the environmental characteristics of the road’s surroundings; and

• technical factors that are connected with road design, construction and traffic characteristics.

Together with air, water is the main transport media for pollution dispersal from roads to the environment. Water is a very efficient solvent and, during its path through the road construction and surrounding environment, it dissolves and trans­ports many pollutants – some of them in large quantities and over long distances...

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