rybina_ea_i_dr_angliiskii_iazyk_dlia_magistrov_i_aspirantov

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could be used for skidding and, at first, for primary hauling. With the advent of logging railroads, high-powered steam donkey engines and skidders could be taken to the timber and cable skidding became possible.

Skidding is now done in many different ways with a wide variety of machines and equipment, ranging from one horse to mammoth tractors or cable skidders. Because skidding is often done over rough or soft ground and on steep slopes, it is advantageous to reduce the friction between logs and ground as much as possible. Not only are larger loads possible when friction is reduced but important time savings are effected.4

Notes:

1.skidway – верхний склад, эстакада

2.deck rollway – площадка для штабелёвки древесины

3.banking ground – склад, откуда производится погрузка бревен для перевозки водой или по ж.д.

4.time savings are effected – в результате получается большая экономия времени.

II. LOADING

Before tree products are transported out of the forest, they must be loaded on some kind of conveyance. Frequently, also "they must be reloaded from one type of conveyance to another "when a transportation system of two or more stages is used.

Products cut in harvesting may be left at the stump for loading; or they may be bunched so that several can be loaded from one point; or they may be concentrated along roads by skidding. Generally, the greater the concentration of products to be loaded at one point, the more highly specialized is the loading operation. Ordinarily only small products are loaded at the stump, as it would be too cumbersome to move a power loader with the capacity for handling heavy products from stump to stump to load them.

Ties, pulpwood, and bolts of various kinds are often hand loaded directly from where they were cut. In many cases, however, small products are bunched, or even skidded before loading when a large volume is removed per acre and the transportation system is ready accessible. Heavier products such as sawlogs, tree length, and poles, are either bunched or skidded, so that several or more can be loaded at one point where either animal or mechanical power may be applied.

Since loading must be gauged to and often coordinate with cutting, bunching, skidding, or hauling, it is a very important step in the harvesting operation. When loading is slower than hauling, for instance, then trucks lose time waiting, if loading capacity is greater than hauling capacity, then the loader

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and crew are idle until an empty truck arrives. Loading is the keystone of an efficient harvesting operation, as it usually determines the size of the cutting, bunching, skidding crews, as well as the number of transportation units needed.

Regardless of where loading is done and upon what kind of conveyance products are loaded, it is necessary to lift them except in those rare instances when loading can be done by gravity or by horizontal movement, as by rolling. This means that power is required to lift the products. Since green wood is heavy and since many forest products are large, powerful loading machines are required on harvesting operations in big timber.

III. LAND TRANSPORTATION

Transportation in timber harvesting means the movement of primary forest products on sleighs, trucks, railway cars, water and vessels. But transportation of primary forest products starts at the stump and includes skidding with horses, tractors, wheeled vehicles, and cables, and finishes when these products enter a mill or other manufacturing plant. Loading, transferring from one conveyance to another, and unloading of wood are all problems of transportation.

Forest products are heavy and bulky. When large quantities are to be delivered regularly, some special means of transportation must be provided unless public roads or highways, common-carrier railroads, or waterways are available for primary transportation.

Because much of the forest area is in undeveloped localities or places with a minimum of transportation facilities, it is generally necessary to install their own transportation system, varying from truck roads to standard-gauge railroads, or systems of dams and streams improvements to make driving possible. The kind of transportation needed depends upon a number of considerations, such as topography, climate, size of operation, distances products must be moved, existing facilities and concentration of timber.

The cost of transportation is, as a rule, the largest single expense on most logging operations. Judgment and experience on the part of the operator is needed to select the best combination of location, method, and standard of road construction and selection of transportation equipment that will give the lowest per unit cost. Harvesting is primarily a transportation problem — that of moving the heavy, bulky tree from stump to mill.

IV. MACHINES FOR LOGGING OPERATIONS

Mobile Debranching Machines

The removal of branches and limbs from a felled tree can be a time consuming operation in logging. Now a new system for speeding-up the

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operation is being tested in Sweden. When perfected it will increase timber output per man hour from about 20 cu. ft. with modern conventional methods to 60-70 cu. ft. A new type of light, portable limbing machine is capable of cleaning all limbs and branches from an average size tree in some 20 seconds.

Efficient machines have been evolved for log barking, but removal of branches and limbs has remained a difficult problem to solve and has been performed by power saws. It has accounted for as much as 40 per cent of the total time required for felling, limbing and topping. It was determined to investigate the possibilities of developing a limbing machine suitable for Swedish conditions. The result was the production of a complete logging system—a station composed of a number of mechanized units, capable of being moved easily from one site to another.

The limbing station is sited close to a transport road and is fed with trees felled within a radius of about 330 yards. The mechanical components consist of the limbing machine mounted on two heavy tyred wheels, a diesel generator set, a slashing arrangement for direct cutting of the debranched timber into lengths and simultaneous sorting of saw logs and pulpwood and a separate cabin from which one man can control all these operations by means of push buttons.

The trees are fed into the limbing machine by a tractor fitted with a specially designed grip device, which swings 360 degrees. This tractor is in turn fed by two to four skidding tractors, which haul the trees from stump. In addition the station includes a tractor loader for handling the logs and a conveyor for stacking the branches. The latter can either be burnt or restored as fertilizer to the forest by the skidding tractors on their return journey for new bundles of trees.

The present test station is manned by 17 men, but when properly run-in and with the aid of new powerful skidding tractors, the number will be reduced to eleven. Four of the men fell the trees with chain saws and the skidding tractor drivers are assisted by two men at the felling site and by one man at the station.

The limbing machine is equipped with eight cylindrical steel cutters, driven by separate electric motors, which are pressed against the tree by hydraulic power. After the root end of the tree has been placed in the machine by the tractor loader it is pulled through by a powerful spike roll at a speed of 148 ft. per minute and arrives at the slashing device completely freed from branches.

V. NEW TYPES OF LOADERS

A new method of logging was adopted in Canada. This method was based on the use of loaders, which have been modified for yarding

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Two machines, a Skagit Sj4RT and a Skagit Sj4R lave both been adapted to combination yard-loading by the addition of a haul-back tower placed immediately over the main drum and the installation of a main boom which will raise 35 feet at the tip to give sufficient cable deflection when yarding in.

These two machines produce 80,000 to 100,000 b.f. per lay at a cost of approximately 4 dollars per 1000 b.f. loaded on the truck. This cost is realized through: 1) a reduction in woods crew, 2) the elimination of a separate loader at the landing; and 3) the speed with which the machines can be moved and relocated. Each yarder-loader is manned by three men; a machine operator, a hooker and chaser. Each machine has an effective yarding distance of 250 feet, the logs being brought right up against the boom and swung onto the truck.

One of the big advantages of these machines is mobility. They will travel over any terrain that a logging truck will roll on.

The machines can be placed at almost any location that has space enough to accommodate the machine and a truck. By swinging the boom to the right or left the log can be directed in its travel to by-pass obstacles that might cause hang-ups. As the log is brought close to the landing the main line raises it off the ground and brings it up against the boom. It is then swung over the waiting truck and placed on the bunk. The flow of the log from the bush to its final position is uninterrupted and in one stage, and it takes only a few minutes.

New Skagit Sj4R yarder-loader1 is the first of its kind in use in Canada. It is powered by a 170 h.p. caterpillar engine and equipped with a transmission which has three speeds forward and three reverse. Through the use of the reverse gearing, logs can be lowered gently onto the truck bunks without relying on excessive use of the winch brake. The single motor powers both the boom operation and the chassis drive.2

First unit, the Sj4RT, is equipped with two engines, one of which drives the chassis and the other powers the winch and boom operation. Both units are equipped with 3/4-inch steel core main line, 1/2-inch haulbacks, and 3/4-inch hemp core steel chokers.

In addition to the two Skagit units and the caterpillar, six logging trucks with 8-foot bunks equipped with 4-foot stakes are used.

Settings arc laid out in blocks 500'X500' square. When a block is to be logged out3 a road is pushed through the middle to form a 250-foot strip on each side. A faller is assigned to each strip and each of his yarder-loaders work a side with its effective 250-foot yarding distance. When this swath is cut the process is repeated in other blocks.

1 new Skagit Sj4R yarder-loader – новая модель канадского погрузчика марки Skagit Sj4R

2 both the boom operation and the chassis drive – и стрелу и шасси

3 When a block is to be logged out – когда необходимо произвести лесозаготовки на группе делянок

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VI. SEMITRAILERS

Logs of more than 20 feet in length usually have to be loaded on the semitrailers. The heavier butt ends are supported by the bunks of the tractor and the lighter ends by the trailer. Depending on their density and size, the weight of large single logs may reach 8 or even 10 tons, and tractors and trailers must be adapted for the safe hauling of heavy loads up to 20 tons and 50 feet in length.

Many of the tractors formerly mounted on double wheels have now been replaced by those with large single wheels. Carrying no load on the return trip to the forest, the trailer bumps along the road, wearing out tires. This is often avoided by loading the empty trailer onto the tractor, and carrying it on the return trip.

To facilitate the loading and unloading of the semitrailer, a simple scaffolding is rigged at the terminal station. Its construction is simple, and suitable timber is usually available on the site. Any available mechanical winch can be used. The telescopic tongue of the trailer is attached to the protective steel frame of the driver's cabin. A cable sling, attached to the centre of the trailer, permits easy lifting and lowering. The frame behind the driver should be strongly built to protect the cabin against any forward shifting of the load on downhill run or on sudden braking.

The minimum hauling distance at which carrying a semitrailer on the return trip is profitable is about 30 kilometres.

In those forests where timber is produced in long lengths it is often hauled by tractors with semitrailers. Another great advantage of the trailer is that it can be loaded without the tractor.

VII. HAULING LOGS BY TRUCKS

Trucks are now the most common means of hauling logs from the landing in the forest to the mill. The efficiency of the truck or tractor-trailer type of log transportation depends largely on its ability to penetrate the forest more easily than can locomotives. Trucks arc also better suited for use in scattered stands of timber or where logs are picked up here and there as in certain cutting systems.

The size of truck to be used will depend on the products to be hauled, the type of roads and bridges over which the haul is made and the distance of the haul. In some operations, trailers are not necessary and are even impracticable for various reasons, such as short logs, soft ground, and number of stops before a load is accumulated. In most logging operations, if logs of 32-ft lengths or longer are being hauled, a truck-trailer combination is required. The bed of the truck supports one end of the load and the trailer the other end. On the return trip from the log dump to the landing the empty trailer is carried on the truck.

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Truck loading is accomplished by numerous methods, the type depending on the log size, truck size, and so on. Hand loading is very costly and inefficient. With the exception of some pulp operations where the logs are easily handled, it is gradually disappearing. Gravity decks where the log is rolled onto the truck are used in some smaller operations as is the crosshaul method of loading. Several types of power loaders are in use today. They are being successfully used throughout the country, not only to load but also to skid logs for short distances.

CIRCULAR SAWMILL FORUM

I am considering buying my first sawmill and my neighbor wants to sell me a used diesel-powered portable mill. I would like to have a stationary mill set up in a building. Is there any problem with using the portable for this application?

For the most part, the major difference between a stationary and a portable mill is the tires. There is, however one fundamental fault that most portable and a few stationary mills share, which is that they are designed to use just one power source to drive just one shaft—which in turn powers everything else in the whole mill.

If you are using a diesel-powered portable mill as a portable mill, then this system has quite a lot of merit, for reasons we'll get to shortly. When applied to a stationary setup, however, it's a bad idea.

I suppose the reason some people still design stationary mills with one shaft driving everything in sight, is a throw-back to the old days when everyone used line shafts. In the days before electricity, most mills were severely limited by their available power source(s). If they relied on a water wheel for power, they certainly weren't going to have more than one at their disposal to hook up to.

As a result, old-time sawmillers had to connect one long shaft and then belt everything that needed to turn, rotate, or revolve to that one shaft through a (sometimes complicated) system of belts and pulleys. Even in fairly recent times when the use of steam or gasoline power sources came into popular use, their cost and size made it impractical to have individual power plants for individual machines. As a result, it made sense to copy the old systems by driving one shaft and powering everything from it.

Today, fortunately, electricity is the average sawmill's power of choice. Even for operations lacking three-phase power, a diesel-electric generator set can solve the problem. One of the many advantages to powering mill equipment with electric motors is that it's fairly easy to size each individual motor to each task at hand. Plus, it's certainly cheaper and more efficient to run wire and

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conduit than it is to add all of the additional bearings, belts, pulleys, and shafting that would be required in a line shaft-powered system.

From a trouble shooting perspective, anyone using a line shaft system regardless of what kind of power drives the shaft—is going to have an awful time trying to solve a vibration problem with all of the machinery turning at the same time. One way would be to start unhooking belts until the vibration goes away. But frankly, when I'm out on a trouble shooting job, I really don't have the time or the patience to mess around with such foolishness when simply throwing a switch makes so much more sense.

Electric motors are also quite a bit quieter than diesels, making it possible to hear a bearing problem, for example, long before you get to see the smoke billowing from it.

If none of what I've said so far matters to you, then you should do yourself a favor and run separate electric motors just for the safety reason of being able to control each motor individually. There are many occasions where you have to trouble shoot or just check something out while it's running— believe me! In these cases you really don't need all sorts of rotating shafts, conveyors, belts, pulleys and saws just waiting to "reach out and touch someone" do you?

White Cedar Regeneration Requires Special Effort

The northern white cedar is one of the most useful trees grown in Michigan and a resource that needs to be expanded to meet demand by people and wildlife.

The question is how.

Doug Lantagne, Extension forestry specialist at Michigan State University, says that the white cedar does not readily reproduce itself— regenerate—and that landowners need to be aware of this.

"Our concern is that private landowners may decide to harvest their white cedar and inadvertently lose the resource," Lantagne says. "We simply want the private landowner to be aware of that possibility and, if they are going to harvest, consult with a private forester or contact their county Extension office before they start cutting."

The white cedar currently occupies about 1.2 million acres of Michigan's woodlands and constitutes about seven percent of the commercial forest.

The tree's commercial value—roughly $6.5 million annually—stems from its use in the manufacture of fence posts, wood shingles and log homes.

White cedar is also excellent winter cover for white-tailed deer, bear, bobcat and about 100 other kinds of wildlife, Lantagne says.

The white cedar is coming under pressure from commercial interests and, to some extent, the white-tailed deer, which likes to browse white cedar

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seedlings. Browsing limits and sometimes prevents white cedar regrowth, especially where the deer population is high.

Lantagne points out that a cutback on harvesting on public lands to preserve wildlife habitat has increased the commercial demand for white cedar grown on private lands. Demand has significantly increased the market value of the tree, and in some areas, Lantagne says, that has resulted in harvest that outstrips tree growth. If the regrowth of the white cedar is not accelerated, there could be a shortage of wood products, a loss of jobs and a loss of cover for wildlife.

Lantagne says that most people who have a keen interest in Michigan's forests know the problem well and a representative group hopes to reverse the decline of the resource.

The group includes representatives from MSU Extension, the U.S. Forest Service, the Michigan Department of Agriculture, the Department of Natural Resources, the wood products industry, tourism and recreation businesses, and environmental organizations.

Among their goals are increased forest management research and increased cooperation among regulatory agencies to expedite the rate of white cedar regeneration. Another goal is development of a plan to grow white cedar by size or class according to market demand in various areas of the state and, during times of high deer numbers in areas where white cedar is being regenerated, to control the herd to prevent seedling damage.

Lantagne encourages private landowners to become part of the effort to maintain and increase the white cedar resource.

"The white cedar is as much a renewable resource as any other agricultural crop, and it can be managed equally for wildlife habitat and commercial purposes," Lantagne says. "There is little reason why the white cedar shouldn't be an economic, recreational and wildlife resource for the landowner."

Until research develops an expeditious way to regenerate stands of white cedar, private landowners should manage the resource carefully, Lantagne cautions.

He says that his department and county Cooperative Extension Service off ices can provide forest management information to private landowners who are interested in maintaining white cedar growth on their property.

8) Геология, поиски и разведка горючих ископаемых

TEXT

1. Calcite cementation is often an important factor in the evolution of reservoir pore systems. Although petrographically obvious, the effect that

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cementation has had on the petrophysical properties of a pore system may be difficult to evaluate quantitatively. To this end, a computer-assisted petrographic image analysis (PIA) technique was developed to quantify porosity and permeability reduction due to calcite cementation.

With this technique, pore area and specific surface of the extant pore system are measured from digital images of core-plug thin sections. Porosity is estimated from the measurements of pore area, and in empirical equation relating pore area and specific surface to core permeability is derived using the Kozeny-Carman expression. In this manner, a permeability model is developed for the pore system in question, thus providing a means of estimating permeability from PIA measurements.

To estimate the porosity and permeability of the precalcite pore system, calcite cement is discriminated from the same digital images and analyzed as pore space. This effectively backstops calcite from the extant pore network to yield the precursor ore network. A comparison of the porosity and permeability of the extant and precalcite pore networks shows the quantitative significance of calcite cementation.

This technique is demonstrated using two dolomite reservoirs that exhibit varying amounts of late-stage calcite cements: Little Sand Draw field, Wyoming, and Bindley field, Kansas. Calcite cement was found to be minor and restricted to moldic pores in Little Sand Draw dolomites, resulting in less than a twofold change in permeability. In contrast, late calcite cements are somewhat more abundant in Bindley dolomites, but more importantly, they occupy intercrystalline pores as well as moldic pores. The net effect was a 10to 1000-fold decrease in permeability and the localized destruction of reservoirquality rocks in Bindley field.

2. Lake Tanganyika, part of the East African rift system, represents one of the most widely cited modern analogs for interpreting ancient rift lakes. To date, few published detailed sedimentologic studies of the modem sediments allow for comparisons to outcropand well-bore-scale observations within ancient strata.

Four recurrent structural margin types exist along the alternating halfgraben structure of the lake: hinged margins, axial margins, accommodation zone margins, and escarpment margins. The hinged margin consists of a series of structurally controlled benches over which long. continuous tracts of bioclastic lag deposits predominate; clastic sands are limited to moderate-size silty deltas and long, narrow shoreface sands. The axial margin is dominated by a wave-dominated, silt-rich delta system. Accommodation zone margins consist of bio-clastic lag deposits atop structural highs, whereas carbonate and clastic mud accumulates farther offshore. Escarpment margins contain small fan-delta deposits alternating along shore with talus deposits; offshore carbonate and

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clastic mud is present away from active gravity-flow deposition. Total organic carbon (TOC) and pyrolysis data from fine-grained samples subtly reflect the contrasts in margin types, but these values are controlled more directly by water depth.

Although facies are similar among all margin types, their spatial distribution, in particular the degree to which facies tracts trend parallel to shore, best discriminates among the different margin types. These data suggest that unique but predictable associations of reservoir, seal, and source facies exist along each of the different margin types.

3. Because most of the Permian basin region of west Texas and southern New Mexico is covered by Phanerozoic rocks, other means must be found to examine the Precambrian upper crustal geology of the region. We have combined geologic information on the Precambrian from outcrops and wells with geophysical information from gravity and magnetic surveys in an integrated analysis of the history and structure of basement rocks in the region. Geophysical anomalies can be related to six Precambrian events: formation of the Early Proterozoic outer tectonic belt, igneous activity in the southern Granite-Rhyotitc province, an episode of pre-Grenville extension, the Grenville orogeny, rifting to form the Delaware aulacogen, and Eocambrian rifting to form the early Paleozoic continental margin. Two geophysical features were studied in detail: the Abilene gravity minimum and the Central Basin platform gravity high. The Abilene gravity minimum is shown to extend from the Delaware basin across north-central Texas and is interpreted to be caused by a granitic batholith similar in size to the Sierra Nevada batholith in California and Nevada. This batholith appears to be related to formation of the southern Granite-Rhyolite province, possibly as a continental margin arc batholith. Because of this interpretation, we have located the Grenville tectonic front southward from its commonly quoted position, closer to the Llano uplift. Middle Proterozoic mafic intrusions are found to core the Central Basin platform and the Roosevelt uplift. These intrusions formed at about 1.1 Ga and are related in time to both the Mid-Continent rift system and the Grenville orogeny in Texas. Because these features are likely to be rift related, they suggest that the concept of a Delaware aulacogen needs to be revised only to the extent that the rifting is Proterozoic in age, not Eocambrian. Precambrian basement structures and changes in lithology have influenced the structure and stratigraphy in the overlying Permian basin, and thus have potential exploration significance. Interpretation of the gravity and magnetic data with geologic information also leads us to suggest the existence of pre-Ellenburger basins, which may be extensive and of potential exploration interest.