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The decision whether to construct a tunnel using a TBM or using a drill and blast method includes a number of factors. Tunnel length is a key issue that needs to be addressed because large TBMs for a rock tunnel have a high capital cost, but because they are usually quicker than a drill and blast tunnel the price per metre of tunnel is lower. [2]
The standard technique requires that inventory be valued at the standard cost of each unit; that is, the usual cost per unit at the normal level of output and efficiency. The retail technique values the inventory by taking its sales value and then reducing it by the relevant gross profit margin.
Use of slags in the construction industry dates back to the 1800s, where blast furnace slags were used to build roads and railroad ballast. During this time, it was also used as an aggregate and had begun being integrated into the cement industry as a geopolymer. [10]
The coking plant that feeds a battery of blast furnaces is just as expensive as the blast furnace and requires a specific quality of coal. [ 63 ] [ 64 ] Conversely, many direct-reduction processes are disadvantaged by the costly transformation of ore into pellets: these cost on average 70% more than raw ore. [ 65 ]
The construction and commissioning of new production units continued. Attention was concentrated on blast furnaces No. 5 and No. 6, and this blast furnace steel became the biggest in the USSR. [12] A number of techniques that impacted the theory and practice of construction were developed at the site.
This definition may be with respect to either the element or isotope weight." A more exact definition is represented by the following equation: MUF = I - 0 + B - E where I designates inputs, 0 designates outputs (which are sometimes subdivided into product and waste streams), B refers to beginning inventory, and E to ending inventory. The three ...
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The new Austrian tunneling method (NATM), also known as the sequential excavation method (SEM) or sprayed concrete lining method [1] (SCL), is a method of modern tunnel design and construction employing sophisticated monitoring to optimize various wall reinforcement techniques based on the type of rock encountered as tunneling progresses.