Housing performance evaluation: challenges for international knowledge exchange

Developing effective building performance evaluation and feedback processes is a vital part of global efforts to reduce building energy use and gain insight into the actual performance of buildings and technologies. Although attempts have been made to introduce internationally agreed models for these processes, it is clear that various countries are producing different approaches according to their cultural, institutional and policy differences. Knowledge exchange is potentially a key means of developing a shared understanding of values, meanings and practices in relation to building performance evaluation. This paper identifies cultural and institutional barriers in the European Union for international building performance communities of practice utilizing knowledge exchange, from an experiential ‘real-world’ perspective. The preparation of a 30-month research project to help develop building performance evaluation in Poland and an associated bilateral symposium is closely evaluated through an action research case study in terms of the stakeholders, the national contexts in which they operated and the key challenges they faced. Recommendations are then made in terms of the support needed to develop more responsive research programmes in relation to developing international knowledge exchange, and the capacity-building elements required for these international communities of practice

Silesian School of Qualitative Research – 20 years of experience and lessons of quality research in buildings with different utility functions

Artykuł składa się z dwóch części. Pierwsza z nich prezentuje dorobek zespołu naukowców i dydaktyków z Wydziału Architektury Politechniki Śląskiej w Gliwicach, którzy od 20 lat realizują badania jakościowe środowiska zbudowanego. Przedstawiono powstanie oraz rozwój Śląskiej Szkoły Badań Jakościowych, specjalizacje i wybrany dorobek publikacyjny zespołu, ogólne informacje o stosowanych technikach i narzędziach badawczych, a także o metodyce przeprowadzania badań terenowych. Druga część artykułu to szczegółowy opis ewaluacji wykonanych w ramach dwóch projektów badawczych. Całość zakończono praktycznymi wnioskami z przeprowadzonych badań jakościowych.The paper consists of two parts. The first presents the achievements of the team of scientists and teachers from the Faculty of Architecture, Silesian University of Technology, who have carried out scientific and teaching work in the field of built environment qualitative research for 20 years. The origin and development of the “Silesian School of Qualitative Research” is presented, specializations and selected publishing achievements of the team, general information about the applied techniques and research tools, as well as the methodology of conducting field research. The second part of the paper is a detailed description of housing environment evaluation carried out within the framework of two research projects. The paper is completed with practical conclusions from the conducted qualitative research processes

NUMERICAL AND EXPERIMENTAL PRESSURE DETERMINATION IN THE VERY NEAR FIELD OF A PIEZOELECTRIC TRANSDUCER

Measurements in the very near eld of piezoelectric transducers are fundamental for many ultrasonic problems. In such cases also the transducer vibrations should be known to perform mathematical models of radiated beams. Acoustic pressure measurements near to the transducer surface can give the necessary information. The pressure of the radiated wave at the transducer surface corresponds to its normal vibration velocity multiplied by the ρc value of the medium. However, this is valid only for the central wave, when the edge wave of the transducer can be ignored. On the other hand, pressure measurements on and very near to the transducer surface are not possible because of the voltage leakage between the electronic transmitter and the PVDF hydrophone used in such measurements. By means of a numerical model, central and edge waves were found for a plane PZT transducer 7.5 mm in radius, with the applied 2.7 MHz voltage pulse composed of 3 cycles. Two types of boundary conditions of Dirichlet and Neumann were considered showing a negligible dierence in the case of short pulses. Basing on numerical and experimental results, practical conditions were determined which make it possible to carry out pressure measurements in the very near eld of the transducer, and hence to determine the transducer vibrations which are important for modeling ultrasonic pulse beams

Possible temperature increases in soft tissues in the case of nonlinear and linear wave propagation

It is well known that the nonlinear propagation increases the absorption of acoustic waves in the medium thus increasing the temperature effects. According to the recently developed new theoretical approach it is possible to determine in a simple way the effective absorption in the case of nonlinear propagation basing on the pulse spectrum analysis [Wójcik, 1996]. In this way it was possible to find the corresponding absorption values occuring in ultrasonography. In this case a classical PVDF membrane hydrophone was used to demonstrate and to measure nonlinear effects. Analysing the obtained wave spectra it was possible to determine the increase of the effective tissue absorption and hence to find the rate of heat generation per unit volume which is crucial for temperature elevations In this way possible temperature increases for the case of nonlinear and linear propagation can be determined

Ilościowa ocena nieliniowej propagacji w wodzie i w tkance

Nonlinear propagation effects were investigated numerically and experimentally u wate r and In blood from the point of view of ultrasonic diagnostic applications in cardlology. Pressure distributions of short and long pulses with the frequency of 3 and 3.5 MHz, radiated by a typical cardiological probe, were found along the ultrasonic beam axis. The numerial results were obtained by means of the numerical code Wf developed previously. The experimental pressure distributions were measured by memu of a membrane PYDF hydrophone. The obtained numerical and experimental results show ing the distributions of the 2-nd and I -st harmonics have shown good agreement allowing us to determine some diagnostic conclusions

Annular Array Transducer and Matched Amplifier for Therapeutic Ultrasound

The use of therapeutic ultrasound continues to grow. A focused ultrasonic wave can increase the tissue temperature locally for the non-invasive cancer treatment or other medical applications. The authors have designed a seven-element annular array transducer operating at 2.4 MHz. Each element was excited by sine burst supplied by a linear amplifier and FPGA control circuits. The acoustic field, generated by a transducer was initially numerically simulated in a computer and next compared to water tank hydrophone measurements performed at 20, 40 and 60 mm focal depth. The results showed good agreement of the measurements with theory and the possibility to focus the ultrasound in the preselected area. The total acoustic power radiated by the annular array was equal to 2.4 W

Thick Film Transducers for High Frequency Coded Ultrasonography

Recently a new technology of piezoelectric transducers based on PZT thick film has been developed as a response to a call for devices working at higher frequencies suitable for production in large numbers at low cost. Eight PZT thick film based focused transducers with resonant frequency close to 40 MHz were fabricated and experimentally investigated. The PZT thick films were deposited on acoustically engineered ceramic substrates by pad printing. Considering high frequency and nonlinear propagation it has been decided to evaluate the axial pressure field emitted (and reflected by thick metal plate) by each of concave transducer differing in radius of curvature – 11 mm, 12 mm, 15 mm, 16 mm. All transducers were activated using AVTEC AVG-3A-PS transmitter and Ritec diplexer connected directly to Agilent 54641D oscilloscope. As anticipated, in all cases the focal distance was up to 10% closer to the transducer face than the one related to the curvature radius. Axial pressure distributions were also compared to the calculated ones (with the experimentally determined boundary conditions) using the angular spectrum method including nonlinear propagation in water. The computed results are in a very good agreement with the experimental ones. The trans- ducers were excited with Golay coded sequences at 35–40 MHz. Introducing the coded excitation allowed replacing the short-burst transmission at 20 MHz with the same peak amplitude pressure, but with almost double center frequency, resulting in considerably better axial resolution. The thick films exhibited at least 30% bandwidth broadening comparing to the standard PZ 27 transducer, resulting in an increase in matching filtering output by a factor of 1.4–1.5 and finally resulting in a SNR gain of the same order