Pees outlines , high transportation costs and labor disputes motivated oil men to continue developing pipeline technology. By , a two-and-a-half mile iron pipeline, complete with pumps helping to move the oil up a foot incline, was laid in Pennsylvania.
The first fully successful pipeline—which used wrought iron and highly reinforced joints to transport between 1, and 2, barrels of oil daily across five miles of land—came in These pipelines were originally intended to allow private companies to control the transport of oil—and it was that power that activists objected to. By the late 19th century, Standard Oil controlled 80 percent of America's oil transportation markets, and oil was too important a resources to be so firmly in the hands of just one private company, reformers thought.
But, as the historian Arthur M. Johnson wrote back in : "When the pipeline issue appeared on the national scene as a subject for public policy, it was too late to change the place that private enterprise and inadequate public policies on the state level had given pipelines in the petroleum industry.
Long ago I lived in Santa Cruz, California. Almost every morning I would throw on a wet suit, grab my surfboard out of the garage, and head to the rocky cliffs just a few blocks from my house. I would When, in , Van Syckel finished his line, of 2-inch pipe screwed together, from a well to the railroad, it worked. People began to notice.
It did the work of teams working 10 hours a day. She said it began a revolution. Then they attacked it with pickaxes. They tied chains to it, and pulled it apart with horses. Someone telegraphed the governor, asking for help. Van Syckel sent for rifles from New York.
The railroaders got mad, too. Employees of the West Penn Railroad Company, sensing a threat from a pipeline that crossed their road, tore it up.
The pipe was relaid, and the railroaders destroyed it again. In this bipartisan fashion, they could do about 8, barrels a day. The teamsters eventually left town en masse. Soon enough, pipeline companies raised their prices, minimally undercutting the bids from the bygone teamsters. T he earliest pipelines led from wells to local refineries, and then, as John D.
Rockefeller consolidated the refineries, straight to railroads. There were dozens of them, in parallel, supplied by places like the Oil Creek Tube Works. Soon enough, the pipelines began to compete with the railroads, and, taking a cue from Rockefeller, consolidated.
Fairview Pipe Line was first to do so. By , it had a 4-inch trunk line to Pittsburgh, 60 miles away. In , the Pennsylvania Transportation Company got a charter to build a pipeline clear across the state, to the sea more than miles eastward. First, though, came pipelines to Cleveland.
Then Buffalo. At last, New York, Philadelphia, Baltimore. Tide Water, though, beat the Pennsylvania Transportation Company in the race to the Atlantic, completing a 6-inch line from Bradford, Pennsylvania to the Bayonne, New Jersey refineries in By , the generation following Van Syckel had built enough 6-inch and 8-inch lines to put a girdle around the world, twice.
To achieve these lengths, pipeliners figured out how far and high pumps could push oil. No single pump, or pipe, could possibly get oil across the Alleghenies alone. So they broke long routes into sections, and built storage tanks and pump stations along the way.
As links make a chain, so conjoined sections made pipelines. And conjoining sections got easier as pipe manufacturers learned to consistently make good screw-threads. Laying these 19th-century trunk lines required a big frame and a strong back.
The pipe, in or foot sections, was hauled into the woods by horse or ox, on a wagon or sled. The pipe was heavy, as were the tools used to manipulate it.
To assemble screw-coupled wrought iron pipe, a foreman banged on the end of the pipe, then another man, bucking it up, rotated it a hair with a huge wrench, called Klein tongs.
The tongs were the length of a man, and just as heavy. A bang, a turn—one, then the other. Through the woods, pipeliners buried the line in a ditch.
Through wetlands, they encased it in concrete. Long days, and longer weeks, proceeded as such. Farmers liked them but sent their daughters to live with aunts in the city when the pipelines came through. After the line was assembled, buried, and filled with oil, linewalkers went out to check for leaks.
Men and tools were requisitioned, and the pipe was dug up and fixed. Hermit-like, linewalkers stayed in sheds along the pipeline. In the spring, many discovered that their pipelines, laid in rivers, had been taken out by floods and ice.
They telegraphed for more supplies and men, who waded into frigid water and fixed the pipe. While different processors have different numbers of steps, they are basically variations of these five, used in the MIPS R processor: fetch instructions from memory read registers and decode the instruction execute the instruction or calculate an address access an operand in data memory write the result into a register If you glance back at the diagram of the laundry pipeline, you'll notice that although the washer finishes in half an hour, the dryer takes an extra ten minutes, and thus the wet clothes must wait ten minutes for the dryer to free up.
Thus, the length of the pipeline is dependent on the length of the longest step. Ideally, each of the stages in a RISC processor pipeline should take 1 clock cycle so that the processor finishes an instruction each clock cycle and averages one cycle per instruction CPI. The processor might occasionally stall a a result of data dependencies and branch instructions. A data dependency occurs when an instruction depends on the results of a previous instruction.
A particular instruction might need data in a register which has not yet been stored since that is the job of a preceeding instruction which has not yet reached that step in the pipeline. The second instructs it to add r3 and r4 and store the sum in r5. We place this set of instructions in a pipeline. When the second instruction is in the second stage, the processor will be attempting to read r3 and r4 from the registers.
0コメント