Fluid flow identification on base of the pressure difference measured on the secant of a pipe elbow

The paper presents a new method for indirect flow rate measurement in elbow flow meters. The idea of the method consists in selecting such a Reynolds number value, assumed as a coefficient in fluid flow equations, which fulfils with set accuracy the condition of equality between the measured and the computed pressure difference at the end points of the secant of the elbow arch. The calculus takes into account also the accurate flow geometry, the values of coefficients which describe the thermo-physical properties of the fluid at the measurement temperature, and proper equations of the turbulence model. A special test stand was arranged in order to implement the proposed method in practice. The numerical computations were carried out using the software package FLUENT 6.1. The results of calculations were compared with the corresponding results of measurements achieved on the stand, as well as ones found in the bibliography [?, ?]. A comparison of the outcome of calculations with experimental readings shows a high grade of consistence.     

The assessment of the umbilical blood flow of the surviving twin after the intrauterine death of the other twin

This paper summarizes our experience with Doppler velocimetry in survivors of intrauterine co-twin demise. In the first trimester, ten dichorionic deaths occurred; none of the survivors developed flow disorders. During the second trimester, there were three intrauterine demises, two of them were monochorionic and the survivors developed flow disorders: one presented transitory venous flow aberration, the other one an impaired development of diastolic flow. In the third trimester, two intrauterine deaths occurred. One case of twin to twin transfusion syndrome (TTTS) was complicated by the donor's death and the recipient showed a loss of diastolic flow. The second one happened during a dichorionic twin pregnancy. The survivor presented high systolic/diastolic daily ratio (S/D = 7.8).     

Steady state of three-fluid parallel-flow heat exchanger system

We study the steady state of a three-fluid parallel-flow heat exchanger system using the nilpotency of the underlying semigroup. It is shown that the heat exchanger reaches the steady state in finite time if the inputs do not change given sufficient time. A formula to calculate the steady-state time is obtained, and it is verified by numerical simulations in the case of constant inputs.     

Logical Representation of a Conceptual Model for Spatial Data Warehouses

The MultiDimER model is a conceptual model used for representing a multidimensional view of data for Data Warehouse (DW) and On-Line Analytical Processing (OLAP) applications. This model includes a spatial extension allowing spatiality in levels, hierarchies, fact relationships, and measures. In this way decision-making users can represent in an abstract manner their analysis needs without considering complex implementation issues and spatial OLAP tools developers can have a common vision for representing spatial data in a multidimensional model. In this paper we propose the transformation of a conceptual schema based on the MultiDimER constructs to an object-relational schema. We based our mapping on the SQL:2003 and SQL/MM standards giving examples of commercial implementation using Oracle 10g with its spatial extension. Further we use spatial integrity constraints to ensure the semantic equivalence of the conceptual and logical schemas. We also show some examples of Oracle spatial functions, including aggregation functions required for the manipulation of spatial data. The described mappings to the object-relational model along with the examples using a commercial system show the feasibility of implementing spatial DWs in current commercial DBMSs. Further, using integrated architectures, where spatial and thematic data is defined within the same DBMS, facilitates the system management simplifying data definition and manipulation.

Static‐Strain Level Change Together with Detection of Transient Signal as Damage Indicator for Truss and Frame Structures

The lifetime prolongation of the old industrial structures is an important economic issue. Damage detection techniques can be helpful to warn about any structural deterioration and to assure sufficient time for counteraction activities. In the paper, the results of strain measurements on scaled leg model of offshore oil platform with different damage cases are presented. The considered damage cases were yielding, chord cutting and brace–chord detachment located in the bottom part of the model. Yielding was detected mainly by the sensors located in the lower part of the structure. On the other hand, brace–chord detachment was detected by all sensors on the structure. Therefore, the global character of the considered damage indicator is proven at least for some important class of damage cases. Due to transient response during brace–chord detachment and interpretation problems of results for partial chord cutting, the necessity of continuous monitoring was evident. The time point of detachment occurrence can be easily detected using difference or cross‐correlation technique. The change in static‐strain levels together with the detection of transient signal seems to be a simple and an effective damage indicator based on interrogation of thermo‐mechanical strains.