Andersen''s syndrome: a distinct periodic paralysis

PURPOSE: To develop a stable, transluminally created abdominal aortic aneurysm (AAA) within a live animal model. MATERIALS AND METHODS: Eight mongrel dogs were utilized to evaluate a new, catheter-based technique for the creation of an AAA. With use of a standard angioplasty balloon and a balloon-expandable intravascular metallic stent, the infrarenal abdominal aorta was overdilated to twice its measured diameter into a fusiform shape AAA in eight dogs. At 30 days, aortography was performed, the dogs were killed, and the aorta was resected and evaluated for histopathology. RESULTS: Seven of the eight dogs that underwent transluminal AAA creation survived the initial procedure. A stable, fusiform AAA was successfully created in these seven dogs. At 30 days, repeat angiography and histologic examination confirmed that the seven AAAs were still twice the diameter of the normal aorta (a four-fold increase in luminal area), that the branch arteries remained patent, and that the lumen was endothelialized. One of the eight dogs was killed 9 hours after the procedure because of inability to awaken from anesthesia. Gross and histopathologic results in this one dog also demonstrated an intact aorta containing an AAA. CONCLUSIONS: A stable, infrarenal AAA model can be successfully created in the canine species with use of standard catheter-based techniques and equipment. This model can be used to test emerging endovascular treatments of AAA.     

Novel Processing of 1-3 Piezoelectric Ceramic/Polymer Composites for Transducer Applications

Piezoelectric ceramic/polymer composites with 1-3 connectivity were made by weaving sized lead zirconate titanate (PZT) fiber bundles through a honeycomb support. Bundles comprised of fine-scale, 20-50 μm green fibers, made using the viscous suspension spinning process, were sized to increase their manageability. The sizing step comprised of soaking the green PZT fiber bundles in an aqueous solution of poly(vinyl alcohol), then pulling the wet fibers through a steel sizing die. Sizing resulted in dense and flexible fiber bundles, which facilitated composite construction and led to composites with increased volume fractons. Sintering, polymer embedding, and machining produced a composite exhibiting 1-3 connectivity. Composites with 10 vol% PZT yilded d ₃₃ values of 230 pC/N and a dielectric constant of 130.     

“Softer” optimization and control models via fuzzy linguistic quantifiers

A “softening” of a basic formulation of multicriterion optimization and control (multistage decision making) is presented. For optimization, instead of seeking an optimal solution that best satisfies all the fuzzy objectives as has been done so far, we seek an optimal solution that best satisfies most, much more than 50%, etc. (a linguistic quantifier, in general) of the fuzzy objectives. For control, we seek in turn an optimal sequence of controls that best satisfies the fuzzy constraints and fuzzy goals at most, much more than 50%, etc. of the control stages. A calculus of linguistically quantified statements based upon fuzzy sets and possibility theory is used. Some applications to softer evidence aggregation in expert systems are also indicated.     

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.     

A min-max procedure for the shakedown analysis of skeletal structures

A solution procedure for elastic-plastic structures subjected to variable repeated loads is elaborated using a min-max formulation of the shakedown problem. This optimization procedure performed in a multi-dimensional space of parameters is transformed and further reduced to a solution of a set of algebraic equations and a one-dimensional minimization problem. To this purpose use is made of relationship between statically admissible residual stresses and plastic strains. The latter, treated in the analysis as free parameters, provide at the end of the optimization process some additional information on possible residual displacements prior to shakedown. Illustrative examples of space frames are presented to show the accuracy of the proposed procedure.     

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.