New Synchronization Method for Transmission Systems with Variable Length of Bits

Based on the Spartan 3E evaluation module, a flexible platform for the implementation of different algorithms for A/D conversion was developed. The aim of presented work was to improve the concept of the sampling rate adaptation to the input signal rate of change in terms of practical issues including synchronization of delta codecs. The new, original synchronization method, useful in systems dedicated for transmission of variable duration of bits was proposed and experimentally verified. Performed measures and observations have shown elimination of the synchronization lose phenomeno

Stosowanie sotalolu w zapobieganiu migotaniu przedsionków po zabiegach pomostowania aortalno-wieńcowego

Migotanie przedsionków (AF) jest jednym z najczęstszych powikłań występujących po zabiegach kardiochirurgicznych i wynosi według różnych autorów 10–50%, w zależności od definicji i metod wykrywania. Najczęściej pojawia się między 2. a 4. dobą po operacji i często nawraca w ciągu pierwszych 30 dni po zabiegu. Ostatnio obserwowany wzrost częstości występowania pooperacyjnego AF prawdopodobnie wiąże się z powiększeniem grupy chorych kwalifikowanych do zabiegów rewaskularyzacji serca. Właściwe leczenie i zapobieganie pooperacyjnemu AF jest niezwykle ważne dla poprawy stanu zdrowia pacjentów i szybszej rehabilitacji, a także zmniejszenia kosztów hospitalizacji. Mimo istnienia jednolitych wytycznych wciąż pojawiają się wątpliwości co do wyboru leku antyarytmicznego i czasu jego wdrożenia do leczenia. Dotychczas opublikowane wyniki badań wskazują na niewątpliwe korzyści płynące ze stosowania terapii antyarytmicznej zarówno w okresie przed-, jak i pooperacyjnym. W wielu dotychczas opublikowanych pracach zwraca się uwagę na istotną rolę sotalolu w prewencji AF u pacjentów poddanych zabiegom kardiochirurgicznym. Jak się wydaje, jest to lek, który w istotny sposób zmniejsza częstość występowania AF. Nadal jednak brak jednoznacznych danych uzyskanych w dużych badaniach klinicznych, dotyczących częstości występowania objawów niepożądanych związanych z leczeniem sotalolem oraz optymalnej dawki leku. Należy również jednoznacznie określić grupy pacjentów, u których ta terapia może być najbardziej skuteczna. (Folia Cardiol. 2005; 12: 77–83

Synchronization of transmission systems with ANS-DM codecs

Adaptive Delta Modulation with Non-uniform Sampling (ANS-DM) is one of the waveform coding techniques, where a sampling instant and a quantization step size are adapted to the signal. The ANS-DM modulator produces an output binary stream, that carries information about the signal and includes necessary data of coder parameters (sampling instant and quantization step). In the demodulator, these values are recovered for proper signal reconstruction. The paper reports the problem of synchronizing clocks (transmitting and receiving) in the (ANS-DM) delta codecs systems. The original synchronization method, valuable in systems dedicated to the transmission of the bits with variable time duration was projected and experimentally verified. Performed measurements and observations have shown the elimination of the synchronization loss phenomenon

ANSDM converters dynamic range design process

The results of analytic and simulating works proved that for nonstationary sources, the delta converters with adaptive sampling expose higher coding efficiency than the former proposals, based on uniform sampling methods. The knowledge of the sampling interval range and the algorithm of the Nonuniform Sampling Delta Modulation and Adaptive Nonuniform Sampling Delta Modulation allows finding the necessary number of the sampling intervals and their values that maximizes SNR. The total dynamic range of the ANSDM modulator is the product of the dynamic range both from sampling interval and step size adaptation. Due to the high complexity of the calculations, the ANSDMsoft program was developed to support computing. All computational works were carried out using the Maple environment. Maple allows to solve complex mathematical functions and display their results in a simple way. Most importantly, it supports the LambertW function, used in the computing of NSDM or ANSDM modulators parameters. Graphic illustrations of the NSDM and ANSDM modulator dynamic range as a function of the minimum and maximum sampling frequency are presented

Mechanical Properties and Microstructure of Austenite—Ferrite Duplex Stainless Steel Hybrid (Laser + GMAW) and SAW Welded Joint

The purpose of the research was to develop a technology for producing thick-walled duplex steel welded joints. The material used in the research was X2CrNiMoN22 duplex steel in the form of a 15 mm thick plate. The welded joint was produced by the modern, high-performance Hybrid Laser Arc Welding (HLAW) method. The HLAW method involves welding a joint using a laser, the Gas Metal Arc Welding (GMAW) method and the Submerged Arc Welding (SAW) method. The HLAW method was used to make the root pass of the double butt welded joint, while the filler passes were made by the SAW method. The obtained welded joint was subjected to non-destructive and destructive testing. The non-destructive and macroscopic tests allowed the joint to be classified to the quality level B. Microscopic examinations revealed the presence of ferritic–austenitic microstructure in the base material and the weld, with different ferrite content in specific joint areas. The analysed joint had high strength properties (tensile strength (TS) ~ 790 ± 7 MPa) and high ductility of weld metal (~160 ± 4 J) heat-affected zone (~216 ± 26 J), and plasticity (bending angle of 180° with no macrocracks). At the same time, hardness on the cross-section of the welded joint did not exceed 280 HV10

Evaluation of the Properties and Microstructure of Thick-Walled Welded Joint of Wear Resistant Materials

The research was conducted on a thick-walled welded joint between the HTK 900H wear-resistant steel plates and the A6 cast profile. The aim of the experiment was to produce a joint with the relevant performance requirements, i.e., a good abrasion resistance joint in the weld face area while ensuring its proper plasticity. The welded joint was made using the MAG PULSE and the high-performance MAG TANDEM methods under automated conditions using the linear welding energy ranging from 1.2 to 2.2 kJ/mm for the different joint regions. The scope of the research included both non-destructive and destructive testing. The non-destructive visual (VT), magnetic-particle (MT), and ultrasonic (UT) tests revealed a good quality of the welded joint with no significant welding imperfections. The microstructure of the welded joint in the weld zone was characterized by a dominant volume fraction of martensite/bainite. The measurement of hardness near the face of the weld confirmed obtaining similar values for this parameter. The HTK 900H steel was characterized by hardness at the level of 383 HV10, whereas the A6 cast-328 HV10, and the weld-276 HV10. At the same time, the analyzed joint showed high ductility in the range of 86 to 159 J. The tests carried out showed that the linear energy control allowed a welded joint with the required performance characteristics to be obtained

Microstructure and Mechanical Properties of Modern 11%Cr Heat-Resistant Steel Weld Joints

In addition to good high-temperature creep resistance and adequate heat resistance, steels for the power industry must have, among other things, good weldability. Weldability of such steels is one of the criteria determining whether or not the material is suitable for applications in the power industry. Therefore, when materials such as martensitic steel Thor 115 (T115) are introduced into the modern power industry, the quality and properties of welded joints must be assessed. The paper presents the results of metallographic and mechanical investigations of T115 martensitic steel welded joints. The analysis was carried out on joints welded with two filler metals: WCrMo91 (No. 1) and EPRI P87 (No. 2). The scope of the investigations included: microstructural investigations carried out using optical, scanning and transmission electron microscopy and mechanical testing, i.e., Vickers microhardness and hardness measurement, static tensile test and impact test. The macro- and microstructural investigations revealed correct structure of the weld, without welding imperfections. The microstructural investigations of joint No. 1 revealed a typical structure of this type of joint, i.e., the martensitic structure with numerous precipitates, while in joint No. 2, the so-called Nernst’s layers and δ-ferrite patches were observed in the weld fusion zone as well as the heat affected zone (HAZ). The mechanical properties of the test joints met the requirements for the base material. A slight influence of the δ-ferrite patch on the strength properties of joint No. 2 was observed, and its negative effect on the impact energy of HAZ was visible