Civil construction is one of the largest consumers of raw materials and producers of waste, which has been causing environmental problems both through the extraction of raw materials and through building activity by g...Civil construction is one of the largest consumers of raw materials and producers of waste, which has been causing environmental problems both through the extraction of raw materials and through building activity by generation of waste. Notwithstanding the need to find an optimum use for solid construction residue to try to solve or minimize this problem, there are no standards for the process of obtaining the CDR （construction and demolition residue）. Thus, the aim of this study was to develop a method of collecting solid waste at the construction site that is easy and low-cost and thus can be applied throughout the construction industry. This collection method was designed to produce residue with the desired proprieties and obtain the best possible homogeneity. This method permitted to evaluate the factors generating construction residue more precisely.展开更多
This paper deals with the problem of theoretical identification of the residence time distribution （RTD） characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situa...This paper deals with the problem of theoretical identification of the residence time distribution （RTD） characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situation is typical for micro-apparatuses （e.g. fluidic element） and also for flow in large arteries. Residence time distribution based on velocity profiles at pulsatile flow of a Newtonian liquid in a rigid pipe will be derived theoretically and compared with the well known results for a constant flow rate E（τ） = τ-^2/2τ^3 at τ 〉 τ^-/2, where E （τ） is differential distribution, x is residence time and τ^- is the mean residence time. The following part of the paper deals stimulus response experimental techniques using tracers. The principal problem related to laminar and convection dominated pulsatile flows is discussed： Can the impulse response also be identified with the actual residence time distribution in the case of variable flow？ The general answer is no, and differences between RTD and impulse responses are evaluated as a function of the frequency and amplitude of pulsatile flows.展开更多
文摘Civil construction is one of the largest consumers of raw materials and producers of waste, which has been causing environmental problems both through the extraction of raw materials and through building activity by generation of waste. Notwithstanding the need to find an optimum use for solid construction residue to try to solve or minimize this problem, there are no standards for the process of obtaining the CDR （construction and demolition residue）. Thus, the aim of this study was to develop a method of collecting solid waste at the construction site that is easy and low-cost and thus can be applied throughout the construction industry. This collection method was designed to produce residue with the desired proprieties and obtain the best possible homogeneity. This method permitted to evaluate the factors generating construction residue more precisely.
文摘This paper deals with the problem of theoretical identification of the residence time distribution （RTD） characteristics of a straight pipe at laminar pulsatile flow, if tracer diffusion can be neglected. This situation is typical for micro-apparatuses （e.g. fluidic element） and also for flow in large arteries. Residence time distribution based on velocity profiles at pulsatile flow of a Newtonian liquid in a rigid pipe will be derived theoretically and compared with the well known results for a constant flow rate E（τ） = τ-^2/2τ^3 at τ 〉 τ^-/2, where E （τ） is differential distribution, x is residence time and τ^- is the mean residence time. The following part of the paper deals stimulus response experimental techniques using tracers. The principal problem related to laminar and convection dominated pulsatile flows is discussed： Can the impulse response also be identified with the actual residence time distribution in the case of variable flow？ The general answer is no, and differences between RTD and impulse responses are evaluated as a function of the frequency and amplitude of pulsatile flows.
