Blog Archives

Optimal stochastic waste-load allocation

Posted by on 26/ 11/ 15

Deterministic waste-load allocation model. Although any number of pollutants may be considered in the overall quality management of a river system, in this example, application a biochemical oxygen demand-dissolved oxygen (BOD-DO) water-quality model is considered.

In LP format, the deterministic WLA model considered herein can be written as

N

Подпись:Maximize ^^( Bj + Dj)

j=i

subject to

1. Constraints on water quality:

aoi + ®ij Bj + ^ ttij Dj < DOsat – DOfd for i = 1,2,…, M (8.59b)

j=1 j=1

2.

Подпись: BL_BjL Ij j Подпись: < Ea for j = j' Подпись: (8.59c)

Constraints on treatment equity:

3. Constraints on treatment efficiency:

Подпись:Подпись:Bj

e-j < 1 – T <e j

j

where Bj, Dj, and Ij are the effluent waste concentrations (mg/L BOD), ef­fluent DO deficit concentration (mg/L), and raw waste influent concentration (mg/L BOD) at discharge location j, respectivel...

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Vardo

Posted by on 26/ 11/ 15

The Vardo is not much more than a full-sized bed flanked by a cou­ple of work surfaces over 35 cubic feet of storage space. It can be pulled behind virtually any car or removed from its trailer to rest in most any truck bed. It is pictured on these pages with an optional fireplace.

ШіЩ

Plans

The plans pictured here are for the Lusby. Those for the rolling houses in­clude instructions for attaching the house to the trailer. Please visit tumble – weedhouses. com for more information.

Endnotes

1. Worldwatch Paper 124, by D. M. Roodman and N. Lenssen, Worldwatch Institute, Washington, D. C., 1996.

2. NPR’s cartalk. com interview with Adam Stein and Tom Boucher.

3. U. S. Bureau of the Census.

4. National Association of Home Builders...

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Diagramming Techniques

Posted by on 26/ 11/ 15

The following three considerations are general techniques that should be followed:

1. Usually only two FAST diagrams are of interest: the diagram that represents an exist­ing plan, program, or design, and the diagram that represents the proposed concept. When diagramming something that exists, be sure not to slip off on a tangent and include alternatives and choices that are not present in the existing system.

2. When using a FAST diagram to design or propose a new concept, restrict it to a specific concept; otherwise, the answers created in diagramming become meaningless. The “method selected” to perform a function brings many other functions into existence. Therefore, creation of several FAST diagrams during system design is a possibility.

3...

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City and countryside

Posted by on 26/ 11/ 15

The historical record shows how important it was for hydraulic engineering to have social utility in Antiquity. Its effects must be recognized by the beneficiaries – but often these beneficiaries are far from the hydraulic projects themselves. If they are in the countryside, they may easily recognize the utility of large irrigation canals, such as the thirty-kilometer long ones on the Euphrates and the Oxus from the IIIrd millennium BC. In these pages we have not often come across the “paradise lost”, the dream of a small community to be able to manage its own technological development at the local level. Such situations probably existed in the very early development of agriculture, and we find it again in the Syrian and Anatolian countryside during the Byzantine Empire...

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Know the pros and cons of carpeting

Posted by on 26/ 11/ 15

Carpeting is not my first choice for a floor covering. In general, inexpensive carpeting doesn’t last long, so it tends to be a significant part of the waste stream clogging our landfills. Fortunately, efforts are now being made to recycle some of the millions of yards of car­peting that are replaced every year.

If you really like wall-to-wall carpeting, 1 recommend using it selectively—in bedrooms, for example. It’s not a good flooring choice in bathrooms, kitchens, and entryways. Don’t install wall-to-wall carpeting where it will get wet and be difficult to keep clean. In those situations, carpeting can collect dust and har­bor dust mites and mold, becoming a poten­tial health hazard. It’s worth it to buy good – quality carpeting that has been treated to resist staining...

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Control of Production Variability

Posted by on 26/ 11/ 15

The standard EN 13108-21 contains a second element of FPC—namely, the control of production variability. This control is applied through the determination of the running mean deviation from the target and is described in Item A.5 of the standard. It involves monitoring systematic trends at the production stages of asphalt mixtures to prevent permanent one-sided deviations. The following parameters of asphalt mixtures are under such supervision:

• Mass percentage of material passing through the sieve D

• Mass percentage of material passing through the sieve D/2 or the charac­teristic coarse sieve

• Mass percentage of material passing through the 2 mm sieve

• Mass percentage of material passing through the 0.063 mm sieve

• Soluble binder content

Calculations of the mean value of...

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Collector Installation at a Glance

Posted by on 26/ 11/ 15

Solar hot-water systems involve a fair amount of labor-intensive planning and plumbing, but a typical collector installation is fairly straightforward.

Подпись: 1 Resources for Solar Information Alternative Energy Store: http://home. altenergystore.com; Solar information and products American Solar Energy Society: www.ases.org; Links, background information on solar energy Database of State Incentives for Renewables and Efficiency (DSIRE™): www.dsireusa.org; Database of energy incentives listed by state and type Find Solar: www.findsolar.com; Worksheets for estimating costs of solar hot- water systems Florida Solar Energy Center®: www.fsec.ucf.edu; Comprehensive site on all things solar, including efficiency ratings of collectors and systems by manufacturer Interstate Renewable Energy Council: www.irecusa.org; News, resources related to renewable energy National Renewable Energy Laboratory: www.nrel.gov; Lots of background information on renewable energy Solar Direct: www.solardirect.com; Solar information and resources Solar Rating and Certification Corp.: www.solar-rating.org; Ratings for solar collectors and systems by manufacturer On this membrane-covered shed roof, (1) the first step was to erect the alumi­num frames that hold the panels. The frames are adjusted to a fixed angle that maximizes the collector’s solar gain and are bolted to blocking that has been integrated into the roof. (2) The panels, which weigh about 100 lb. each, are carried up and clipped onto each pair of frames. (3) Simple compression fittings connect the panels to plumbing. (4) The installers added two more panels and finished in about half a day. They spent another two days setting up the system.

Collector Installation at a Glance

Подпись: ю

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Appendix A: Span Tables

Posted by on 26/ 11/ 15

Using Span Tables

Table One is an abbreviated version of Table R502.3.1(2), from the International Residential Code for One – and Two – Family Dwellings. This particular table, just one of many in IRC codebook, is for floor joist spans for common lumber species, and assumes that we are designing for a residential living area with a live load of 40 pounds per square foot (40 PSF), a dead (structural) load of 10 PSF and an allowable deflection of 1/360.

Table Two is an abbreviated form of Table R802.5.1(7), from the International Residential Code for One – and Two – Family Dwellings. This table is helpful in designing rafter spans for anticipated 70 PSF snow loads on a 20 PSF dead load.

Lets do a couple of exercises, using Table Two:

Example 1: If I want rafters to be two-feet (24") on-cente...

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Installing casing

Posted by on 26/ 11/ 15

Casing hides the joint between the dry – wall and door jamb or window surround It comes in many styles, from 1 x square – edged stock in varying widths to milled casings (see the drawing above). When casing doors, I buy 14-ft. lengths to cut down on waste. Sometimes door casing is available in 7-ft. piecesthat have a 45° miter already cut on one end. Like exterior casings, doors and windows can be either picture-framed (with 45° miters at the corners) or wider trim can

Подпись: Instead of using a tape measure, get more accurate measurements by holding the casing stock in place and marking it.

be butt jointed. I generally nail casing back from the edge of the jamb about 3/i6 in. to leave a reveal.

Reveals make life easier for a carpenter. When wood pieces are nailed flush, they absorb moisture or dry out, moving back and forth in the process, so that flush pieces seldom stay flush...

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Install the interior-door hardware

Posted by on 26/ 11/ 15

Interior-door handles and locks are installed in essentially the same manner as those used on exterior doors. Most interior doors just require a handle and a latch, or what is com­monly known as a passage-door lockset. However, for bedroom and bathroom doors, you may want a privacy lock—an interior lockset that locks when you push or turn a button.

Install the bathroom hardware and fixtures

One of your primary concerns when installing fixtures in a bathroom is to make sure they won’t come loose in a month or two. A toilet paper holder, for example, should be screwed into solid wood and not into drywall alone. This is why we installed backing in the bath­
room walls when we framed the walls (see chapter 4)...

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