Boxcar

Thus we are challenged by the problem of measuring a small signal against the background of one much stronger. The problem is usually solved by one of two means (a) lock-in-amplifier detection and (b) a boxcar type of detection (to some extent we can include double-input optical multichannel detection in this category). 

Because of the railroad-car shortage that has persisted for many years, boxcars are often used for bulk materials. Lined with suitable materials to prevent contamination and with special bulkheads at each door, these cars are acceptable substitutes for covered hopper cars even though unloading is more difficult. Vacuum conveying wands are used to pick up the material, as are front-end-loader-type vehicles. 

Track hoppers are needed for some boxcar and bottom-dump-car shipments. Since boxcars discharge to one side, fairly light construction can be used for the hoppers, which are located to one side of the tracks. However, for bottom-dump cars, the hoppers must be located on the centerline of the tracks. This requires heavy track girders over a hopper and feeder conveyor pit, but hopper depth must be set to give sufficient angle for material to flow well. Belts or reciprocating-plate feeders commonly carry the material to the bucket elevator. 

There are several variations of this basic size, including the well-used Grocery Manufarturers of America size of 1220 by 1015 mm (48 by 40 in). The choice of the exacl size depends on the truck and boxcar width normally available, the size of the package load, and the cus-tomers receiving and handling facilities. Ideally, the sum of the... 

While the Eulerian system has intuitive appeal, it is the Lagrangian coordinate system that is more convenient mathematically and in many practical applications. In this system, the coordinate is fixed to the material and moves with it. It is sometimes called the material coordinate system. In Fig. 2.2, the boxcars can be numbered, so the position of a car in this system never changes. By convention, the Lagrangian coordinate (h) is chosen so that it is equal to the Eulerian coordinate (x) at some time t = 0. Figure 2.10(b) illustrates a Lagrangian h-t diagram of the same system as shown in Fig. 2.10(a) with the Eulerian system. Because the flow is independent of the coordinate system chosen to describe it, both systems must lead to the same results. 

Prior to the containerization movement, work at ports and railyards was vei y slow and labor-intensive because much of the freight being moved entailed unprotected palleted cargo from ships and less-than-carload freight moved in boxcars. It took a lot of... 

Chalcopyrite, CuFeS2, is an important source of copper. A typical chal-copyrite ore contains about 0.75% Cu. What volume of sulfur dioxide at 25°C and 1.00 atm pressure is produced when one boxcar load (4.00 X 103 ft3) of chalcopyrite ore (d = 2.6 g/cm3) is roasted Assume all the sulfur in the ore is converted to S02 and no other source of sulfur is present. 

Generally, best results are achieved in depressed and atrophic or rolling and boxcar scars. Icepick scars always need to be preceded by punch excision. Our experience shows that in older patients, when skin is less elastic, it is possible to achieve more significant improve-... 

Fig. 9.9. A 52-year-old patient with boxcar acne scars before (a) and 1 month after (b) deep chemical peel and skin abrasion...

Atrophic scars (icepick, rolling, boxcar) Hypertrophic scars (keloids)... 

Boxcar scars are round to oval depressions with sharply demarcated vertical edges, similar to varicella scars (Fig. 11.10).They can be divided into shallow (0.1-0.5 mm) or deep (>0.5 mm). 

Useful with icepick and narrow-deep boxcar scars that are excised with a 1.5-mm punch biopsy and sutured with a 6.0 or smaller suture. Nonabsorbable sutures are preferred to avoid inflammation and must be removed within 5 days. 

Useful with wide-shallow boxcar scars associated with laser resurfacing. It is made with different biopsy punch, according to the size of the scar. The scar is first excised and then the punched specimen is elevated higher than the surrounding skin and fixed with a suture. 

Useful with shallow boxcar and rolling scars. CO2 and/or Er YAG lasers are utilized for this technique. After the treatment, silicone sheeting, gauze and tube netting are placed over the treated area and maintained for 24 h (the silicone sheeting remains for another 48 h). The patient is instructed to soak the treated area every 2-4 h with cold water for 20 min and then apply an occlusive ointment. Re-epithelialization is completed in 10 days. A new treatment can be performed after 6-8 weeks. 

In order to compress the measured data through a wavelet-based technique, it is necessary to perform a series of convolutions on the data Becau.se of the finite size of the convolution filters, the data may be decomposed only after enough data has been collected so as to allow convolution and decomposition on a wavelet basis. Therefore, point-bypoint data compression as done by the boxcar or backward slope methods is not possible using wavelets. Usually, a window of data of length 2" m e Z, is collected before decomposition and selection of the appropriate... 

Fig. 20. Performance of data compression techniques (a) orthonormal wavelet (b) backward slope (c) boxcar.

The reverse occurs in the production of foams and consumer items. These plants are usually constructed close to the prospective markets. Insulating materials are often so light that the cost of shipping per ton is very high. Only a small amount of mass can be loaded in a boxcar or truck. The density of polystyrene is 2.4 lb/ft3 (38.5kg/m3). It is made from styrene, which has a density of 56.3 lb/ft3 (902 kg/m3). The foam product occupies 23 times as much space as the styrene, and the polystyrene would cost between 10 and 20 times as much to ship. 

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