Military University of Technology (MUT, Polish: Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego – WAT) is the civil-military technical academic institution in Poland, located at Bemowo, Warsaw. It was established in 1951. The university's rector-commander is płk. Przemysław Wachulak. The university is supervised by the Minister of National Defence of Poland and conducts scientific research for the needs of Polish Armed Forces. Currently the university educates almost 10,000 students. The staff consists of about 1,000 employees, including 220 professors.University leads both military and civilian studies. Military graduates receive not only professional title of magister inżynier, but are also promoted to military rank of podporucznik (second lieutenant). Formally being professional soldiers, military students attend school on the principles of ordinary military service. They are quartered in military dormitories and attend a variety of different military trainings and lectures. After graduating, they are formally obliged to serve in Polish Armed Forces under threat of reimbursement of education costs. Only Polish citizens are eligible for military studies.Contrary to military students, civilian ones can study normally, without any commitments to the Ministry of National Defence. Civilian studies allow to obtain professional titles such as: inżynier or licencjat (first cycle studies), magister inżynier or magister (second cycle studies) and a scientific degree of doktor. Due to changes in Polish law, since October 2019, separate Doctoral School operates in the structure of MUT. Full-time studies are free, extramural studies are payable.Obviously, scientific research conducted in MUT focus on issues connected with military and national defense. MUT was the place where in 1963 first Polish laser was created. In 1964 analog computer ELWAT (later produced by Elwro in Wrocław) was also created in MUT. One of the biggest contemporary projects which was developed at the university was so-called Modular Firearm System, 5.56 mm MSBS rifle, currently manufactured and further developed by FB "Łucznik" Radom. The rifle is to become the next main service rifle of the Polish Armed Forces.
In this study, the initial and fatigue-evolved yield surfaces of Laser Powder Bed Fusion (LPBF)-fabricated stainless steel (SS) grade 316 L were experimentally characterised for three build orientations: horizontal (XY), inclined at 45 degrees (ZX45), and vertical (Z). Uniaxial tensile tests revealed that XY printed specimen exhibit higher mechanical properties than those printed in other orientations. Initial yield surfaces were determined in axial-shear stress space using sixteen proportional loading paths and were fitted using isotropic (Tresca and Huber-von Mises-Hencky) and anisotropic (Hill48 and Szczepinski) yield criteria. The results demonstrated clear deviations from isotropic yielding, with the Szczepinski criterion providing the best agreement with the experimental yield points. Axial stress-controlled fatigue tests were subsequently performed with periodic interruptions at intervals of 20,000 cycles. At each interruption, the yield point was measured to capture the progressive evolution of the yield surface. The results showed orientation-dependent distortional hardening, characterised primarily by asymmetric evolution of axial tensile and compressive yield strengths, while shear yielding remained largely unchanged. Microstructural analysis confirmed that this evolution correlates with orientation-dependent changes in lattice misorientation and accumulated plastic strain.
The paper demonstrates the application of the knife-edge scanning technique combined with a revolving object to dimensional computed tomography (CT). The presented arguments are equally valid for specific technical variants of the technique, such as a revolving scanner. The irradiation system is modified in comparison to that typically applied in CT, but the object is analysed within the same slice-plane. The proposed Scanning Computed Tomography (SCT) method is validated mainly by numerical modelling, and it is shown that it has significant potential in improving the measurement resolution. This results from the procedure of the data registration and the following application of the conventional software, including elaboration of the sinogram subsequently processed with the inverse Radon transform (IRT). The modelling is applied for the reconstruction of both an arbitrary-shaped aperture and intensity distribution in a radiation nano-focus. The proof-of-concept experiment was conducted in the visible spectrum range and for the Fresnel (near-field) zone.
This paper presents the Tykhonov well-posedness of variational–hemivariational inequality with history-dependent operators. Some theorems are deduced to illustrate the continuous dependence of the solution with respect to the data. Next, concrete example of the model from contact mechanics is presented for which the tools presented in this paper can be applied.
The search for innovative solutions in the field of construction materials used in aircraft manufacturing has led to the development of composite materials, particularly CFRP polymer composites. Composite airframe components, which are required to have high strength, are joined using mechanical fasteners. Considering that the composite consists of a polymer matrix, which is a material susceptible to rheological phenomena occurring rapidly at elevated temperature, there is a high probability of significant changes in the strength and performance properties. Coupled thermal and mechanical loads on composite material joints occur in everyday aircraft operation. Experimental tests were conducted using a quasi-isotropic CFRP on an epoxy resin matrix with aerospace certification. The assessment of changes in the strength parameters of the material itself showed a decrease of approx. 40% in its short-term strength at 80 °C compared to the ambient temperature and a decrease in the load-bearing capacity of single-lap bolted joints of over 25%. Even more rapid changes were observed when assessing the fatigue life of the joints assessed at ambient and elevated temperature. In addition, the actual glass transition temperature of the resin was determined using the DSC technique. Analysis of the damage mechanisms showed that at 80 °C, the main degradation mechanisms of the material are accelerated creep processes of the CFRP and softening of the matrix, increasing its susceptibility to damage in the joint area.
Trends of essential climate variables are often estimated from climate data records to quantify changes in the Earth system. An understanding of the uncertainty in a trend is essential for accurately determining the significance of a trend and attributing its causes. Despite this importance, trend-uncertainty estimates rarely account for all known sources of uncertainty. Common approaches neglect measurement-system instability or neglect the impact of natural variability on trend uncertainty. Such neglect can result in over-confidence in trend estimates. This study addresses trend-uncertainty assessment, particularly the need to account for the combined effects of measurement instability and natural variability on the trend uncertainty. The study presents a novel, unified framework for trend estimation that combines available measurement uncertainty information with empirical modelling of natural climate variability to achieve a more accurate uncertainty estimate. The framework is demonstrated for a time series of global mean sea level observations, obtaining more realistic trend-uncertainty values. The framework is applicable to most other climate data records. Adopting this approach will enhance confidence in climate change analysis through more accurate trend-uncertainty assessment in climate studies.
