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Log reduction is a measure of how thoroughly a decontamination process reduces the concentration of a contaminant. It is defined as the common logarithm of the ratio of the levels of contamination before and after the process, so an increment of 1 corresponds to a reduction in concentration by a factor of 10.
Marcus's method is a structural analysis used in the design of reinforced concrete slabs.The method was developed by Henri Marcus and described in 1938 in Die Theorie elastischer Gewebe und ihre Anwendung auf die Berechnung biegsamer Platten. [1]
The Wood–Armer method is a structural analysis method based on finite element analysis used to design the reinforcement for concrete slabs. [1] This method provides simple equations to design a concrete slab based on the output from a finite element analysis software.
What is often called a "log reduction" (technically a reduction by one order of magnitude) represents a 90% reduction in microbial population. Thus a process that achieves a "6-log reduction" (10 −6 ) will theoretically reduce an initial population of one million organisms to very close to zero.
Z-value is a term used in microbial thermal death time calculations. It is the number of degrees the temperature has to be increased to achieve a tenfold (i.e. 1 log 10 ) reduction in the D-value . The D-value of an organism is the time required in a given medium, at a given temperature, for a ten-fold reduction in the number of organisms.
Similarly, at larger depths, silt and sand particles may crush and cause a reduction in pore spaces, reducing the biological activity. Bacterial activity is also impacted by challenges such as predation, competition, pH, temperature, and nutrient availability. [55] These factors can contribute to the population decline of bacteria.
The steel shuttering pinches the top surface of a concrete slab due to the weight of the next slab being constructed. Concrete slabs, block walls and pipelines are susceptible to cracking during ground settlement, seismic tremors or other sources of vibration, and also from expansion and contraction during adverse temperature changes.
Once this is defined, design code gives standard prescriptions for w/c ratio, the cement content, and the thickness of the concrete cover. This approach represents an improvement step for the durability design of reinforced concrete structures, it is suitable for the design of ordinary structures designed with traditional materials (Portland ...