Characteristics of centrifugally cast GX25CrNiSi18-9 steel

The paper presents the results of microstructural examinations of the industrial heat-resistant centrifugally cast GX25CrNiSi18-9 steel characterised by increased content of Cu. The study included changes in the microstructure of base cast steel respective of the steel held at a temperature of 900 and 950°C for 48 hours. Based on the results obtained, an increase in microhardness of the examined cast steel matrix with increasing temperature was stated, which was probably caused by fine precipitates enriched in Cr, Mo, and C forming inside the matrix grains.The layer of scale formed on the tested cast steel oxidised in the atmosphere of air at 900 and 950°C was characterised by an increased tendency to degradation with increasing temperature of the conducted tests

Macroscopic Hematuria—A Leading Urological Problem in Patients on Anticoagulant Therapy: Is the Common Diagnostic Standard Still Advisable?

All urological standards of care are based on the past definition of the clinical importance of macroscopic hematuria. The aim of the study was to assess the phenomenon of iatrogenic hematuria in current clinical practice and analyze its origins in patients receiving anticoagulant drugs. Retrospective analysis of clinical documentation of 238 patients that were consulted for hematuria in 2007–2009 by 5 consultant urologists was performed. In the group of 238 patients with hematuria, 155 (65%) received anticoagulants. Abnormalities of urinary tract were found in 45 (19%) patients. Estimated cost of a single neoplasm detection reached the value of 3252 Euro (mean 3-day hospitalization). The strong correlation between the presence of hematuria and anticoagulant treatment was observed. Authors suggest to redefine the present and future role of hematuria from a standard manifestation of serious urological disease to a common result of a long-term anticoagulant therapy

Tests used to check the working precision of heavy machine operators

W artykule podano podstawowe informacje na temat dokładności sterowania ręcznego. Przedstawiono krótki opis badań eksperymentalnych, mających na celu poprawę jakości sterowania ręcznego operatorów maszyn roboczych. Omówiono strukturę oraz możliwości diagnostyczne testu komputerowego, stworzonego do celów monitorowania dokładności pracy operatorów maszyn roboczych poddanych m.in. oddziaływaniu drgań niskich częstotliwości w warunkach laboratoryjnych.The paper provides the basic information about the precision of manual control. Experimental tests are described that are used to improve the quality of manual control among machine operators. The main focus is on the structure and diagnostic potentials of a computer test, developed to monitor the working precision of machine operators exposed to low-frequency vibrations in laboratory conditions

Laboratory setup to investigate the impacts of general and local vibrations on the human body

W artykule przedstawiono stanowisko laboratoryjne do badania wpływu drgań niskiej częstotliwości na organizm operatora maszyny roboczej. Opisano budowę stanowiska, jego parametry techniczne oraz możliwości zastosowania. Stanowisko umożliwia niezależne wzbudzanie w warunkach laboratoryjnych drgań ogólnych i miejscowych w zakresie niskich częstotliwości oraz hałasu. Za pomocą specjalnie stworzonego Testu służącego do badania dokładności pracy oraz wykorzystując możliwości omawianego stanowiska możliwe jest badanie wpływu wibracji i hałasu na dokładność pracy badanej osoby.The study outlines the design of a laboratory setup to investigate how low-frequency vibrations should affect the machine operators. The structure, technical parameters and potential applications of the setup are explored. The setup enables the independent generation of low-frequency general and local vibrations in laboratory conditions. The special test developed to monitor the working precision supported by the laboratory facilities allow for investigating the impacts that vibrations might have on the operators' working precision

Convergent traffic in the environment of wireless MESH technology

The paper presents a performance study of wireless MESH networks in the context of the convergent transmission. Nowadays, the integration of voice, video and data is becoming the norm. However, the wireless LAN environment, and especially MESH technology is an unfriendly environment due to its characteristics. Therefore, the impact of the size of transmitted frames to delays in the network based on mesh technology was analyzed. The sizes of transmitted frames corresponded to standards for Voice over IP, Video over IP that are commonly used. Additionally, a model of effective load balancing in mesh networks was presented. Then, the reliability and flexibility of these networks will be increased

Ocena wpływu mączki chalcedonitowej na przebieg reakcji alkaliów z kruszywem reaktywnym w zaprawach cementowych

Chalcedony dust can be used as a mineral additive in cements and concretes. This material can act as a pozzolan and prevent the expansion caused by the alkali-silica reaction. The paper presents the examination of cement mortars with reactive opal aggregate and various quantities of chalcedony dust conducted using a long-term method as set out in the ASTM C227. A petrographic analysis as well as tests of potential reactivity of opal aggregate were carried out by chemical method as specified in the ASTM C289. The microstructure of cement mortars with chalcedony dust and opal was also examined. The tests showed a positive effect of the chalcedony dust additive on the reduction of the expansion caused by the alkali-silica reaction compared to the mortars without the additive. The addition of 20% of chalcedony dust to cement mortars lowers the expansion to a safe level that does not exceed 0.1% after 360 days (as set out in the ASTM C227).Mączka chalcedonitowa może być wykorzystywana jako dodatek mineralny do cementów oraz betonów. Surowiec ten może działać jak pucolana i zapobiegać ekspansji wywołanej reakcją alkalia-krzemionka. W referacie przedstawiono badania zapraw cementowych z reaktywnym kruszywem opalowym oraz różną ilością dodatku mączki chalcedonitowej metodą długoterminową wg ASTM C227. Wykonano analizę petrograficzną oraz badania potencjalnej reaktywności kruszywa opalowego metodą chemiczną zawartą w normie ASTM C289. Przeprowadzono również badania mikrostruktury zapraw cementowych z mączką chalcedonitową i opalem. Badania wykazały pozytywny wpływ dodatku mączki chalcedonitowej na ograniczenie ekspansji wywołanej reakcją alkalia-krzemionka w stosunku do zapraw bez tego dodatku. Dodatek mączki chalcedonitowej do zapraw cementowych w ilości 20% obniża ekspansję do bezpiecznego poziomu, nieprzekraczającego po 360 dniach 0,1% (według normy ASTM C227)