A new method of determination of the permeability of vapors of volatile liquid substances through polymer membranes

A new apparatus for the determination of vapor permeability of volatile liquid substances through polymer membranes has been described. The permeability of the vapor is calculated from the measurements of the depression rate of the liquid meniscus in a calibrated capillary tube. The conditions of the measurements by means of the described method are very close to those of the average and practical application of foils. The method is characterized by a simple design of the apparatus, easy handling, and simplicity of the determinations, so it may constitute the basis of vapor permeability determination standards. The results obtained by means of the described method were compared with those derived from the partition cell method.     

Dilatometric studies of the phase transitions of sodium potassium tartrate tetrahydrate (RS)

Temperature dependence of the thermal expansion coefficients of Rochelle salt (RS) crystals for the basic crystallographic directions have been measured in the temperature range from 100 K to 308 K by an air-capacitor dilatometer. Anomalies of thermal expansion coefficients at about 210 K and 153 K have been observed, besides these corresponding to known ferroelectric phase transitions at the temperatures of 255 and 297 K.     

Kalman filtering of traffic fluctuations for real-time network management

Discrete- time stochastic models of sequential traffic records in telephone networks are considered. They appear to be well suited for a use of the Kaiman filter. A version of the filtering algorithm is adopted to deal with traffic fluctuations. The overall approach is tested against the real data gathered by the supervisor of the French toll network. The adaptive traffic estimator is inserted into a simulator of a testbed network operated in the urban zone of Paris. The traffic estimations provided by the filter are used to decide an overflow hierarchy.     

General Probability of System Failure

This paper presents a general method to determine probabilities of failure of any fixed subset of coherent system components under various conditions. The method uses a known reliability structure of the system and the known joint probability distribution of its component times-to-failure. This method is universal and can be applied in many cases. Nevertheless, for large systems it is troublesome. In practice a problem is solved using a numerical program.     

Teaching Multibody Dynamics at Warsaw University of Technology

The paper concerns the usage of the method of multibody systems (MBS) in teaching students at the Warsaw University of Technology. Research results from the MBS discipline are being used in several ways. Large-scale computer software is being used to illustrate lecture material, some MBS research results are included in lecture topics and independent courses are taught, based directly on MBS research. During senior courses, advanced software is also used as a computational tool as well as an integral part of Virtual Prototyping. The paper presents also several examples of student projects created with MBS.     

Apparatus for real-time measurement of particle size distribution

In this paper we describe an apparatus for real-time measurement of particle size distribution. By introducing a fast moving water stream with suspended particles and stroboscopic illumination, a large number of pictures (samples) can be analysed by means of a TV camera connected to a computer. In this manner complete particle size distribution is achieved with minimal delay. Satisfactory results were obtained when the apparatus was tested as an on-line device in a flotation plant, demonstrating the full ability of the system to control the flotation process.     

Finite rotations in the description of continuum deformation

Finite rotations in continuum mechanics are described by means of either a proper orthogonal tensor or finite rotation vectors. Some algebraic relations concerning the finite rotations are reviewed. Formulae expressing them in terms of displacements are given. Along each of the curvilinear coordinate lines the finite rotations are shown to satisfy some systems of the linear first-order differential equations. Each system of the equations is presented in four different but equivalent forms associated with an intermediate stretched basis or with an intermediate rotated basis. Integrability conditions of the system of equations provide various alternative forms of compatibility conditions in continuum mechanics. The displacement field is expressed through the stretch and rotation fields in the form of three successive line integrals. The formula describes the displacements to within a constant finite translation and a constant finite rotation. The procedure proposed here generalizes the formula derived by Cesàro (1906) within the classical linear theory of elasticity.     

Mathematical foundations of the quasistatic approximation in reactor physics

The quasistatic method used in reactor-physics calculations is applied to a model integro-differential equation in a Banach space. The resulting quasistatic equations are shown to be locally consistent with the original initial-value problem. An iterative scheme to solve these equations is presented and shown to be convergent.     

Odor active compounds content in spices and their microencapsulated powders measured by SPME

Within this study, main odorants of marjoram and thyme (linalool and thymol) were determined in spices and microencapsulated powders using solid-phase microextraction (SPME). Analyses were conducted on selected batches of spices before and after decontamination and on microencapsulated powders prepared for technological purposes (improvement of aroma in decontaminated spices). Conditions of SPME analyses were determined for individual compounds and matrices. Determination of total and surface contents of compounds and the percentage dependencies between encapsulated and surface aroma made it possible to identify the best powders in terms of their quality.