Gravity driven counterflow through an open door in a sealed room

Flow measurements using tracer gas techniques were made on the exterior doorway of a test house for indoor-outdoor temperature differences of 0.5–45 K. The time for door opening and closing was constant at 3.75 s, and fully open hold time varied from 0.5 s to 120 s. Predictions of a variable density steady flow model were in good agreement with the measurements when adjustments were made for the time-varying size of the opening and for the effect of cross-stream mixing between the incoming and outgoing air streams. The flow rate is shown to be governed by an effective density very close to the average of inflow and outflow densities, and the control condition at the doorway is fixed by the jet-like behavior of the inflow stream. Dependence of cross-stream mixing on interfacial stability caused the orifice and coefficient to increase from 0.4 to 0.6 as temperature difference increased. This varying orifice coefficient is well represented by the combination of a discharge coefficient for streamline contraction combined with a mixing coefficient which accounts for mixing between the inflow and outflow.     

Object–Oriented Enterprise Modeling and Simulation of AEC Projects

In this paper we describe an object–oriented framework for developing enterprise models of Architecture, Engineering, Construction projects, and a methodology for formalizing these models such that they can be used for discrete event simulation of information processing and coordination in project execution. The simulation results can be used to predict the probable effects of carrying out proposed changes in planning and managing projects.
In our enterprise modeling framework we represent engineering design projects in terms of deliverables (requirements and solutions), plans (activities and process relations), and organization (participants and organizational relations). The resulting project model is the starting point for identifying coordination requirements between project team participants. Our methodology uses matrix techniques derived from qualtiy function deployment (QFD) to identify interactions between project requirements and solutions and calculate measures of product complexity . We then describe information flow between project activities in a similar matrix and calculate measures of process uncertainty . Finally, we identify the responsibilities of project team members and use a matrix to point out organizational interdependencies .
We apply our framework and methodology to model and simulate engineering design for a major extension of an electrical power substation. Our simulation results demonstrate how project performance is contingent on the fit between the project policies and the objectives and preferences of the project team.     

Relations of calculated and actual settlement of a thawing foundation bed

Conclusions 1. The dependence of relative compression of thawing soil on pressure is nonlinear, and it is in agreement with views on the nature of deformation of thawing soil. A dominance of natural pressure in the total load on a foundation bed permits one to use the method of unit summation in calculating settlement of nonlinearly deformable soil. Such calculations, as compared with the linear formulas employed in SNiP, give better agreement with actual settlement.2. In calculating settlement of thawing foundation beds, we need differential consideration of soil compressibility with depth, since the combination of genetic features of frozen ground and the increasing natural pressure with depth may create a different inhomogeneity in the foundation bed.Yakutniproalmaz, Mirnyi. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 1, pp. 18–21, January–February, 1975.     

Procedure for predicting settlements of thawing bases for engineering calculations

It was shown that in order to compute the settlement of thawing cohesive soil under a load in time it is necessary to experimentally determine the consolidation coefficient. A procedure is suggested for determining this coefficient, as well as use of the classical solution of a differential equation for seepage consolidation to describe the settlement of soil, thawing of which can occur according to any law.State All-Union Scientific Research Institute of Roads. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 4, pp. 5–7, July–August, 1993.     

A new approach for simulating aerodynamic vibrations of structures in a wind tunnel—development of an experimental system by means of hybrid vibration technique

The present paper describes a newly proposed technique for simulating aerodynamic vibration of structures, which is referred to as the hybrid vibration technique or HVT. This technique is a combination of step-by-step computer calculation and measurement of the aerodynamic force acting on a model structure in a wind tunnel test. Even though the HVT can be applied effectively, problems still exist with respect to obtaining accurate simulations. These problems include response delay in controlling the model behavior and the inertia force component present in the measured aerodynamic force. Techniques for compensating for response delay and for eliminating inertia force from measured aerodynamic force are applied to a developed system based on HVT simulations of aerodynamic vibration of elastic structures and structures exhibiting elasto-plastic behavior are performed by means of the newly developed system. The effectiveness of the techniques for compensating for the response delay and eliminating the inertia force can be confirmed from the results of the simulations. In addition, the possibility and applicability of HVT is indicated.     

Concurrent denitrification and oxygen uptake in microbial films

Mixed microbial films were grown on the inner walls of a tubular reactor with recirculation of the reactor contents and continuous flow-through of nutrient solution. The loss of total oxidized nitrogen was correlated to the film population, the nitrite concentration and the dissolved oxygen concentration in the reactor. When film population was greater than 0.5 × 10⁹ cells cm⁻², reactor dissolved oxygen concentration greater than 1 mg l⁻¹ had little effect on the nitrate loss. Nitrate loss declined for film populations greater than 2 × 10⁹ cells cm⁻². Models based on Monod and zero-order microbial kinetics were calibrated using these data and a nonlinear least squares method. There was little difference in the residual errors with these methods.