PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 13

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Energochłonność instalacji chłodniczej w dużym obiekcie handlowym. Porównanie kosztów eksploatacyjnych instalacji freonowych i C02 w supermarkecie
Zachariasz K.
Chłodnictwo i Klimatyzacja
|
2018
|
nr 7
60--62
PL
Koszty eksploatacji instalacji chłodniczych, w szczególności koszty zużycia energii elektrycznej, stanowią temat wielu opracowań naukowych i artykułów w czasopismach branżowych. Dyskusja o wydatkach na energię budzi zawsze żywe zainteresowanie przyznać trzeba, że nie jest to dyskusja łatwa ze względu na mnogość czynników, jakie należy uwzględnić.
2
Content available Doppler effect in the cw fm sonar
Marszal J., Salamon R., Zachariasz K., Schmidt A.
Hydroacoustics
|
2011
|
Vol. 14
157-164
EN
When sonars are used for military purposes they have to ensure unobtrusive operation, afeature that can be potentially secured by ‘silent sonars’ or continuous wave frequency modulation sonars (CW FM sonars). The article presents how these sonars operate and identifies the relations between their parameters. The Doppler effect and its impact on the CW FM sonar are studied to identify how it affects the sonar’s parameters. The results of simplified theoretical calculations are supported with results of computer simulations of a more realistic model.
3
Content available Modernization of ASW sonar SQS-56 at Gdansk University of Technology
Marszal J., Schmidt J., Salamon R., Kilian L., Raganowicz A., Zachariasz K., Ostrowski Z., Jedel A., Rudnicki M., Sidorko T.
Hydroacoustics
|
2010
|
Vol. 13
191-196
EN
The fast development of electronic technology and digital signal processing methods makes electronic devices, including sonar systems ones, obsolete very quickly. On the other hand the ships mechanical components including mechanical parts of sonars are operational for a few dozens of years. It makes good opportunity to modernize these devices by using modern electronic devices and new digital signal processing methods with application of existing antenna and mechanical systems. The paper presents the modernization of ASW sonar SQS-56 on the Polish frigate ORP “Kościusko”. The aim of modernization, the new parameters of the sonar and block diagram after modernization are presented.
4
Content available Broadband LFM signal source for a module-based diver detection sonar
Zachariasz K., Lis W., Elminowicz A.
Hydroacoustics
|
2010
|
Vol. 13
269-278
EN
A new approach to design of the diver detection sonar’s sounding pulse source is pre-sented. It is based on modules comprising 8 or 16 elements of the transducer grouped on the transmitting channel. The basic advantage of this solution is that it reduces significantly the number of group transmitters. The required output power and topology of the transmitters were determined through theoretical estimation and measurements in a four terminal network. Measurements were taken of the frequency characteristics in the transducer modules includ-ing the compensation system used. It is demonstrated that the source level is most irregular in the transducer under examination when the transducer’s voltage has a constant amplitude, i.e. with parallel compensation. It is also demonstrated that by appropriately selecting ele-ments for a series compensation of the transducer, the frequency characteristics becomes more regular and source level is increased at the extreme ends of the working bandwidth. The result is a compensated characteristics on the receiving side.
5
Content available Method for improving multibeam sonar bearing accuracy
Leśniak W., Marszal J., Salamon R., Zachariasz K., Schmidt J.
Hydroacoustics
|
2009
|
Vol. 12
98-108
EN
The paper presents a simple method for improving multibeam sonar bearing accuracy. The principle proposed here is similar to the monopulse method, a solution commonly used in radars and sonars. With no manual or automatic beam rotation, the method offers a substantial reduction in the demand for sonar computational effort. It significantly reduces bearing error for a relatively high signal to noise ratio. The paper gives a boundary value of the output signal to noise ratio which when exceeded satisfactorily improves bearing accuracy.
6
Content available High accuracy hydroacoustic system to study codend model parameters
Marszal J., Schmidt J., Jedel A., Schmidt A., Wojan Z., Zachariasz K., Leśniak W.
Hydroacoustics
|
2008
|
Vol. 11
271-278
EN
An important task of fishing gear designers is to develop effective selective fishing gears by optimizing its geometry. The high accuracy hydroacoustic system for codend geometry measurements was designed for developing the construction of cod codend for the Baltic fishery. The system consists of 10 pairs of hydrophones, measuring microprocessor device and notebook computer. The high frequency short pulse excitation combined with the matched digital filtering make it possible to obtain high resolution of measure data. Additionally the thermistors mounted in the hydrophones are used to calculate the local sound velocity and enable precision calibration of obtained measuring data. The construction solutions, the measuring procedure and examples of obtained data are presented below.
7
Content available Underwater communication system for shallow water using modified MFSK modulation
Schmidt J., Zachariasz K., Salamon R.
Hydroacoustics
|
2005
|
Vol. 8
179-184
EN
The paper describes the design and operation of the Modified MFSK system for underwater communication. Its function is to transmit data and commands from ships to underwater objects in shallow coastal waters and lakes. The system was primarily required to ensure energy efficiency in its underwater section and the minimum of transmission errors. The emphasis was on non-linear distortions produced in piezoelectric transducers, an untypical source of errors.
8
Content available Hydrographic echosounder for sounding inland waters
Jedel A., Kilian L., Marszal J., Ostrowski Z., Wojan Z., Zachariasz K.
Hydroacoustics
|
2004
|
Vol. 7
89-96
EN
This article describes a new echosounder model designed specifically for institutions responsible for the management of inland waterways, artificial and natural reservoirs, and marine coastal waters. The basic requirement related to the need of sounding shallow waters is measuring the smallest possible depths. Using separate transducers (sending and receiving) and attenuating them, and introducing a high dynamic range TVG circuit allowed the measurement of depths from 20cm at a maximum range of 100m. Water temperature is measured in order to include sound velocity corrections. The echosounder is manufactured using modern technology, with a PC 104 computer, robust FLASH memory emulating a hard disk, 8 inch color LCD panel, thermal printer with paper band for instant profile printouts, and a floppy disk drive for permanent storage. The echosounder interfaces to GPS.
9
Hydroakustyczny system transmisji danych w wodach płytkich z zastosowaniem modulacji MFSK
Schmidt J., Zachariasz K., Salamon R., Kilian L.
Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje
|
2001
|
Vol. 83, nr 27
289-292
EN
The paper presents a hydroacoustic system for the transmission of digital data in shallow coastal waters of which multi-path propagation and intense reverberations are characteristic. To ensure a small error probability of moderate speed transmission, the system uses Corrective Hamming's codes and a technique of incoherent modulation MFSK (Multi Frequency Shift Keying). To synthesise the transmission signal, estimate the spectrum of the signal received and code and decode the channels, a DSP processors are used. The paper includes the results of a simulation in which the system was put to work in the presence of Gaussian noise. The system was tested in shallow lake waters and the first results are discussed in the paper.
10
Content available Code signals transmission using MFSK modulation in shallow waters
Zachariasz K., Schmidt J., Salamon R.
Hydroacoustics
|
2001
|
Vol. 4
261--264
EN
The paper presents an acoustic system for the transmission of digital data in shallow coastal waters of which multi-path propagation and intense reverberations are characteristic. To ensure a small error probability of moderate speed transmission, the system uses corrective codes and a technique of incoherent modulation MFSK (Mufti Frequency Shift Keying). To synthesise the transmission signal, estimate the spectrum of the signal received and code and decode the channels, a DSP processor was used. The paper includes the results of a computer simulation in which the system was put to work in the presence of Gaussian noise. The system was tested in shallow coastal waters and the results are discussed in the paper.
11
Content available Uogólniony opis średniego ciśnienia akustycznego w quasiliniowym przybliżeniu parabolicznycznym
Zachariasz K.
Hydroacoustics
|
2000
|
Vol. 3
63--68
EN
Harmonic generation in the nearfield of the harmonically excited cireular piston souree is considered. The quasilinear parabolic model is used to determine the averaged pressure over the planar receiving transducer of a diameter equal to that of the souree. The model is then simplified by assumption that the receiving transducer covers the entire section of the aeoustie beam. The derived general expressions are used in sample computations of the second and third harmonie eomponents of the averaged pressure in distilled water. The resuLts ofcomputations are eompared with the results obtained from direct numerical integration (so ealled Bergen eode) of the KZK equation and with the experiment conducted in distilled water.
12
Content available Multibeam sonar with hexagonal array
Salamon R., Marszal J., Kilian L., Jedel A., Ostrowski Z., Raganowicz A., Rudnicki M., Wofan Z., Zachariasz K.
Hydroacoustics
|
1999
|
Vol. 2
133--138
EN
The paper presents a multi-beam digital sonar that was designed for monitoring and fish stock assessment in in/and waters. The sonar can also be used as a bottom profiler in lakes, rivers and shallow sea areas. The hexagonal piezoelectric transducer array co-operates with a commutator set. The 32 -channel digital beamformer creates 30 narrow receiving beams in every 60o sector of simultaneous observation. The six sectors cover the whole 360o angle range of the sonar. The beamformer digital signal processing is based on second order sampling of echo signals and the phase-shifting principle of beam deflection. The sonar block diagram, beamformer algorithms, as well as transducers designs are discussed.
13
Content available The estimation ot virial coefficients via the third harmonics measurements
Leble S. B., Zachariasz K., Vereshchagina I. S.
Hydroacoustics
|
1997
|
Vol. 1
83--88
EN
The derivation of the next nonlinear term of the KZK equation is done within original perturbation scheme on the base of the virial expansion for thermic equation of state. We also derived equations for second and third harmonic components in the nearfield of the sound wave generated by a piston transducer. Calculation scheme for a numerical estimation of the integrals for the fundamental and second harmonics is proposed as well as for the averaged third harmonic component. Some results of performed calculations are given for the illustration of the method possibility and comparison with direct finite difference solutions of the KZK equation.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.