Weld metal deposit (WMD) was carried out for standard MMA welding process. This welding method is still promising mainly due to the high amount of AF (acicular ferrite) and low amount of MAC (self-tempered martensite, retained austenite, carbide) phases in WMD. That structure corresponds with good impact toughness of welds at low temperature. Separate effect of these elements on the mechanical properties of welds is well known, but the combined effect of these alloy additions has not been analyzed so far. It was decided to check the total influence of nickel with a content between 1% to 3% and molybdenum with content from 0.1% up to 0.5%.
We talk to Dr. Katarzyna Błachowiak-Samołyk, professor at the Department of Marine Ecology at the PAS Institute of Oceanology in Sopot, about the impact of human activity on life in the oceans.
Investigations were carried out in the regions of the Hornsund Station, Spitsbergen at summer 1979. The aim of the studies was to determine the effect of the Station on the natural environment around the Station. After taking an inventory of the sources of pollution and in result of the determination of the range of the pressure of anthropogenic factors the whole area under degradation was divided into three parts: an area without possibilities of recultivation, a devastated area and an area of normal natural environment. It was found thąt the main source of the contamination of tundra are fuels derived from mineral oil. The distribution of fuel concentrations in the soil corresponds to the direction of the slope of the ground and the flow of the surface waters. Mechanical transformation of the surface of the tundra is also an outcome of the degradation.
Blank handgun shots, party balloon bursts, and a pneumatic compressor with a small-diameter nozzle were used as sources of sound in the assessments of reverberation time, T. The two first sources were of impulse type, while the third one resembled a noise signal source. In this work, 532 values of T were experimentally obtained in four rooms of different volumes and compared. The T values for 1/3 octave frequency bands were found to be independent of the sound source. Reverberation times for the A-frequency-weighting filtered signals were close to one another for the shots and balloon bursts, while those obtained using the compressor nozzle were significantly shorter. The latter effect can be attributed to the relatively high share of high frequency waves in the sound generated by the nozzle. The results show that balloon bursts can be used as handgun shot substitutes in the assessments of reverberation times. While the nozzle noise is rather unsuitable for this purpose, it can be applied in the assessments of T for high frequency waves, up to the ultrasound range. Such acoustic climate information may be useful in designing spaces for high frequency sound-sensitive individuals, e.g. animal shelters.
Pewien buddyjski mnich wybierał się w długą i uciążliwą podróż. Jako towarzysza podroży wziął służącego, który znany był z krnąbrności i kłótliwości. Zapytany o powód tego wyboru oświadczył, że chce się ćwiczyć w cierpliwości i skromności. Dla mnie taką nauką były trzy lata prowadzenia międzynarodowego projektu CHIHE.
According to UNESCO, in 2015, the sculpture as the artistic medium was third among financed public residency art programmes. Contemporary public art and cultural programmes across Europe were focused on finding a balance between cultural identity and cultural diversity among the communities. Therefore, aesthetics and function became a significant issue related to the exploration of participatory design on public sculpture. In this paper, an adopted model of Kurt Lewin’s force field analysis was used to explore the function of sculpture in the public space. The aim was to further evaluate inclusive design to answer the question: Does contemporary sculpture in the public space evoke a certain kind of group dynamic process?
The modified configuration of the 155 mm rocket assisted projectile equipped with lateral thrusters was proposed. Six degree of freedom mathematical model was used to investigate the quality of the considered projectile. Impact point prediction guidance scheme intended for low control authority projectile was developed to minimize the dispersion radius. Simple point mass model was applied to calculate the impact point coordinates during the flight. Main motor time delay impact on range characteristics was investigated. Miss distance errors and Circular Error Probable for various lateral thruster total impulse were obtained. Monte-Carlo simulations proved that the impact point dispersion could be reduced significantly when the circular array of 15 solid propellant lateral thrusters was used. Single motor operation time was set to be 0.025~s. Finally, the warhead radii of destruction were analyzed.
A theoretical approach was applied to investigate the impact of nonlinear standing waves underneath a horizontal deck. A solution was achieved by applying a boundary element method. The model was applied to predict impact pressure underneath a deck. The results show that the wave impact is a very complex momentary process. The influence of initial boundary conditions, wave parameters and deck clearance on impact pressure are analysed. The analysis shows that purely sinusoidal waves of very small amplitude may cause an impact pressure several orders of magnitude higher than a pressure arising from typical applications of a linear wave theory. The analysis shows that all these non-intuitive outcomes arise from the complexity of a wave impact process and its enormous sensitivity to initial conditions what indicates serious difficulties in a reliable prediction of a wave impact for complex wave fields or other structures. Laboratory experiments were conducted to validate theoretical results.
The concept of social capital is gaining increasing popularity among economists and governance practitioners. This is due to the recognition of the fact that a high level of social capital is important for the creation of socio-economic development of countries or territories – economic areas with a high level of connections between entities, organisations and residents. The formation of social capital, understood as the ability to cooperate with various social groups and operate efficiently within these groups, depends on the political system as well as the adopted norms and attitudes, education, styles of management in business organisations and public sphere entities, family ties, motivation to act, etc. The aim of the paper is to indicate various limitations of social capital development and to demonstrate that it is important to involve different communities in its formation In addition, attention is drawn to the fact that social capital generates externalities that are essential for the efficiency and eff ectiveness of governance in territorial systems, both in the economic and public utility sphere.
The hulls of naval ships are exposed to forces and moments coming from internal and external sources. Usually, these are interactions that can be described mathematically by harmonic and polyharmonic functions. The shock of UNDEX type (underwater explosion) works completely differently and its time waveform is difficult to describe with mathematical functions as pressure vs. time. The paper presents a simplification of physical and mathematical models of 1-D kickoff pressure whose aim is performance the simulation of the external force of the detonation wave. The proposed models were verified and tuned on naval, sea trials. The main goals of the proposed models are to perform simulation calculations of the detonation pressure for different explosion charge weights from different distances of the UNDEX epicentre for the design process of machine foundation. The effects of pressure are transformed as impulses exposed on shock absorber mounted at light shock machine.
Prof. Paweł Rowiński, Vice-President of the Polish Academy of Sciences, talks about how climate change will affect Poland and what signs of it should we look for in our rivers.
Although the Antarctic has avoided the worst effects of alien species, its future seems endangered due to increasing natural and man-made pressures. Rapid changes in three major environmental variables have occurred in the Antarctic region during the last decades. In the short term terrestrial biota are likely to benefit from reduced environmental stresses, but in the long run the colonization of the region by lower latitude species with greater competitive ability will become increasingly important and can lead to large-scale changes in biological composition and trophic complexity in some existing Antarctic terrestrial ecosystems. Moreover, the recent dynamic climate changes combined with human activities in the Antarctic region might modify the status of several alien species which have hitherto been considered transient or persistent and could, therefore, become naturalized and threaten the native communities on a larger scale than today, or influence the status of naturalized species.
This paper presents the measurement of vibrational properties of sundatang soundboard. Sundatang is a plucked stringed traditional musical instrument that is popular among the Kadazandusun communities in Sabah, Malaysia. The vibrational properties of the soundboard are measured using CADA-X impact hammering system in a condition where the instrument is without any string. There are two types of sundatang used in this study; one made from acacia and the other from vitex wood. In this measurement, frequency response functions (FRFs) and modal parameters of the top plate and back plate of this instrument are obtained. It is found that in free edge, fundamental frequency of both plates of acacia sundatang is greater than the vitex sundatang in a range of 112 Hz to 230 Hz. However, in clamped edge (attached to its ribs), it was modified to a lower frequency and closer to each other in the range of 55 Hz to 59 Hz. Another finding is the detection of the excitation of similar mode shape at different resonance frequencies. This phenomenon is termed as Different State of Mode (DSM) which is observed may be because the number of testing points is not enough. Findings of this study provide important information to the study of quality development of this instrument
The present work, presented the study of effect of different inoculants on impact toughness in High Chromium Cast Iron. The molds were
pouring in industrial conditions and samples were tested in laboratory in Faculty of Foundry Engineering at AGH. Seven samples were tested
- one reference sample, three with different addition of Fe-Ti, and three with different addition of Al. The samples were subjected to impact
toughness on Charpy hammer and the hardness test. The presented investigations indicate that for the each inoculant there is an optimal
addition at which the sample obtained the highest value of impact toughness. For the Fe-Ti it is 0.66% and for Al is 0.17%. Of all the
examined inoculants best results were obtained at a dose of 0.66% Fe-Ti. Titanium is a well-known as a good modifier but very interesting
results gives the aluminum. Comparing the results obtained for the Fe-Ti and Al can be seen that in the case of aluminum hardness is more
stable. The hardness of all samples is around 40-45 HRC, which is not high for this type of cast iron. Therefore, in future studies it is
planned to carry out the heat treatment procedure that may improves hardness.
Very well-known advantages of aluminum alloys, such as low mass, good mechanical properties, corrosion resistance, machining-ability,
high recycling potential and low cost are considered as a driving force for their development, i.e. implementation in new applications as
early as in stage of structural design, as well as in development of new technological solutions. Mechanical and technological properties of
the castings made from the 3xx.x group of alloys depend mainly on correctly performed processes of melting and casting, design of a
mould and cast element, and a possible heat treatment.
The subject-matter of this paper is elaboration of a diagrams and dependencies between parameters of dispersion hardening (temperatures
and times of solutioning and ageing treatments) and mechanical properties obtained after heat treatment of the 356.0 (EN AC AlSi7Mg)
alloy, enabling full control of dispersion hardening process to programming and obtaining a certain technological quality of the alloy in
terms of its mechanical properties after performed heat treatments. Obtained results of the investigations have enabled obtainment of a
dependencies depicting effect of parameters of the solutioning and ageing treatments on the mechanical properties (Rm, A5 and KC impact
strength) of the investigated alloy. Spatial diagrams elaborated on the basis of these dependencies enable us to determine tendencies of
changes of the mechanical properties of the 356.0 alloy in complete analyzed range of temperature and duration of the solutioning and
ageing operations.
The material selected for this investigation was low alloy steel weld metal deposit (WMD) after MAG welding with micro-jet cooling. The
present investigation was aimed as the following tasks: analyze impact toughness of WMD in terms of micro-jet cooling parameters. Weld
metal deposit (WMD) was first time carried out for MAG welding with micro-jet cooling of compressed air and gas mixture of argon and
air. Until that moment only argon, helium and nitrogen and its gas mixture were tested for micro-jet cooling
The paper presents the results of research of impact strength of aluminum alloy EN AC-44200 based composite materials reinforced with
alumina particles. The research was carried out applying the materials produced by the pressure infiltration method of ceramic preforms
made of Al2O3 particles of 3-6m with the liquid EN AC-44200 Al alloy. The research was aimed at determining the composite resistance
to dynamic loads, taking into account the volume of reinforcing particles (from 10 to 40% by volume) at an ambient of 23°C and at
elevated temperatures to a maximum of 300°C. The results of this study were referred to the unreinforced matrix EN AC-44200 and to its
hardness and tensile strength. Based on microscopic studies, an analysis and description of crack mechanics of the tested materials were
performed. Structural analysis of a fracture surface, material structures under the crack surfaces of the matrix and cracking of the
reinforcing particles were performed.
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