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Energy Centered Planning and Development (ECP&D)
Published in Marvin T. Howell, Energy Centered Management:, 2020
In other words, it is the average demand/peak demand for a given period of time. From your electricity bill, get the kWhs used and the peak kW. Next look for days included in the bill. Multiply these days by 24 (hours per day). Divide this number into the kWhs. Then divide what you get by the peak kW. Multiply this number by 100 to get the percentage. For example: If a facility used 125,000 kWh in July where the billing period covered 30 days, the peak kW demand was 218, and the ELF is calculated by (125,000/30 × 24/218) × 100 = 79.64%.Action should be initiated to increase load factor when you are 60% or lower. If low, shift electricity intensity processes to other times. By increasing load factor, you will reduce the impact of monthly demand (kW) charged on your electric bill.This calculation only needs to be done quarterly to ensure ELF has not significantly changed.Goal—ELF 60% or higher
Error and uncertainty
Published in W. Schofield, M. Breach, Engineering Surveying, 2007
True error (εx) similarly can never be found, for it consists of the true value (X) minus the observed value (x), i.e. X − x = εx Relative error is a measure of the error in relation to the size of the measurement. For instance, a distance of 10 m may be measured with an error of ±1 mm, whilst a distance of 100 m may also be measured to an accuracy of ±1 mm. Although the error is the same in both cases, the second measurement may clearly be regarded as more accurate. To allow for this, the term relative error (Rx) may be used, where Rx = εx/x Thus, in the first case x = 10 m, εx= ±1 mm, and therefore Rx = 1/10 000; in the second case, Rx = 1/100 000, clearly illustrating the distinction. Multiplying the relative error by 100 gives the percentage error. ‘Relative error’is an extremely useful definition, and is commonly used in expressing the accuracy of linear measurement. For example, the relative closing error of a traverse is usually expressed in this way. The definition is clearly not applicable to expressing the accuracy to which an angle is measured, however.
Basics
Published in William Bolton, Engineering Science, 2020
A percentage is an expression which shows a number expressed as a fraction of a hundred and is denoted using the percent sign %. Thus 7% means the number 7 as a fraction of 100, i.e. 7/100. Percentages are one way of expressing numbers that are part of a whole. Nothing is represented by 0 as a fraction of 100 and so 0%, and the whole amount of 100 as a fraction of 100, is 100%. A percentage is thus an expression of an amount as part of the whole. Thus 50% of a cake is 50 parts in 100 or half of the cake. In Section 1.5 you will come across the term percentage error. This is just the numerical value of the error in a quantity expressed as a fraction of what the error would be if the entire amount was error and the result multiplied by 100: percentage error=error in quantitysize of quantity×100ExampleA rod of length 120 cm has a length of 36 cm cut from it. What was the percentage of the rod that was cut off?The fraction of the rod that was cut off was 36/120 and so the percentage removed was: percentagecutoff=36120×100=30%
Effects of moisture damage and anti-stripping agents on hot mix asphalt dynamic modulus
Published in Road Materials and Pavement Design, 2020
Jose Corrales-Azofeifa, Adrian Ricardo Archilla, Fabiola Miranda-Argüello, Luis Loria-Salazar
Parameters in (as well as those in ) define the shape of the sigmoid. Figure 2 shows the effect on the master curve of a percentage change in , with all else equal. Since is negative, it is important to define carefully what is meant by a percentage change. In this case, the percentage is defined as 100 times the difference between the modified value and the original value divided by the original value. With a negative original value, a negative percentage change indicates a less negative value of , which shifts the curve to the right ( changes only the shape of the sigmoid but not its maximum or minimum values). In effect, this means that as shown in the chart, negative percentage changes (or a net increase in the parameter value) decrease the values of log(|E*|) across all frequencies. However, as shown, the reduction is not uniform (as noted above, since the maximum and minimum are not changed, as or , the differences must approach 0).