Mateusz Banaszkiewicz, from the SWPS University of Social Sciences and Humanities in Warsaw, talks about the effects of thinking and acting automatically, and how to fight destructive habits.
In the Fugleberget catchment area (Spitsbergen, Hornsund Fiord region) the growing season lasted 95 days, with growth beginning under the snow. In this time shoots of moss Calliergon stramineum reached a mean length of 19 mm and mean biomass of 0.593 mg dry weight. Annual primary production of moss communities amounts to 220-270 g dry weight per square meter per year. In the first year of destruction the dead plant material lost 30-45% of its initial value, after 10 years only ca 25% of the initial amount of organic matter was left.
The investigation results of the reclamation of spent moulding sands with furfuryl resin are presented in this paper. The reclamation
process was performed in the secondary reclamation chamber of the REGMAS 1.5 vibratory reclaimer. 70 kg portions of moulding sands,
previously subjected to the primary reclamation and dedusting, were used. The secondary reclamation was performed in two stages: the
first consisted of determining the reclaimer intensity at various reclamation times (5 min, 10 min and 15 min) and various electrovibrator
frequencies (40 Hz, 50 Hz and 60 Hz), the second consisted of determining the influence of additional crushing elements on the intensity
of processes.
During potato desiccation the above-ground parts can be destroyed by mechanical, mechanical-chemical, or chemical methods. In the current study, the mechanical-chemical method was used and instead of chemical compounds natural nonanoic acid (pelargonic acid) was used. Nonanoic acid is a natural active ingredient that can be extracted from vegetable oil (rapeseed oil). It is a short chain fatty acid and a natural product, that fits well with the principles of the Green Revolution, which has introduced restrictions worldwide on the use of chemical plant protection products and promotes natural ones. For comparison carfentrazone-ethyl and glufosinate-ammonium were used. Studies were carried out in Poland during 2012–2014 with the potato variety Ikar, which is known to be among the varieties difficult to desicccate in Poland. The results show that potato leaves were efficiently destroyed by both nonanoic acid and chemicals (carfentrazone-ethyl and glufosinate-ammonium). The level of destruction varied from 94.5% to 99%. The level of stalk drying caused by nonanoic acid was high and it was similar to that of chemical desiccants. None of the studied desiccants significantly affected yield, vascular necrosis or quantity of starch in tubers.
The article presents research on modelling fracture in softwood bent elements. This kind of timber is the one most exploited for construction. Authors present a brief review on the subject with emphasis on three basic attempts: Linear Elastic Fracture Mechanics (LEFM), Continuum Damage Mechanics (CDM) and Hill’s Function (HF). Proposed 3D solution bases on Hill’s Function applied in the ABAQUS FEM code. The new idea includes isolating theoretical compression and tension zones in a model. Then, it is possible to distinguish between compressive and tensile strength and predict a real behaviour of bent elements. Introducing general dependencies between material properties leads to the need of determining only longitudinal elastic modulus (EL) and modulus of rupture (MOR). It is practical because these parameters are the main reported in a scientific and technical literature. Authors describe all of the assumptions in details. The experimental tests and Digital Image Correlation method (DIC) validate the FEM model.
The results of investigations of thermal reclamation of spent moulding sands originating from an aluminum alloy foundry plant are
presented in this paper. Spent sands were crushed by using two methods. Mechanical fragmentation of spent sand chunks was realized in
the vibratory reclaimer REGMAS. The crushing process in the mechanical device was performed either with or without additional
crushing-grinding elements. The reclaimed material obtained in this way was subjected to thermal reclamations at two different
temperatures. It was found that a significant binder gathering on grain surfaces favors its spontaneous burning, even in the case when
a temperature lower than required for the efficient thermal reclamation of furan binders is applied in the thermal reclaimer. The burning
process, initiated by gas burners in the reclaimer chamber, generates favorable conditions for self-burning (at a determined amount of
organic binders on grain surfaces). This process is spontaneously sustained and decreases the demand for gas. However, due to the
significant amount of binder, this process is longer than in the case of reclaiming moulding sand prepared with fresh components.
The results of investigations of spent moulding sands taken from the mould at various distances from the surface of the produced casting,
are presented in the paper. The casting mould was made with an application of the cooling system of the metal core in order to increase the
cooling rate of the ladle casting. As temperature measurements in the mould indicated the heat flow from the metal did not create
conditions for the complete burning of a moulding sand. The analysis was performed to find out changes of spent moulding sands caused
by degradation and destruction processes of organic binders. Conditions occurring in the casting mould were discussed on the bases of
testing: ignition losses, dusts contents, pH reactions and the surface morphology of the moulding sand samples. Factors limiting the
effective mould degassing were pointed out. Operations, possible for realization, which can limit the reasons of a periodical occurrence of
increased amounts of casting defects due to changing gas evolution rates being the result of the technological process, were also indicated.
The paper presents possibility of using biodegradable materials as parts of moulding sands’ binders based on commonly used in foundry
practice resins. The authors focus on thermal destruction of binding materials and thermal deformation of moulding sands with tested
materials. All the research is conducted for the biodegradable material and two typical resins separately. The point of the article is to show
if tested materials are compatible from thermal destruction and thermal deformation points of view. It was proved that tested materials
characterized with similar thermal destruction but thermal deformation of moulding sands with those binders was different.
The obtained results of heating of sand moulds with binders by means of a thermal radiation of liquid metal are presented in this study.
Standard samples for measuring Rg made of the tested moulding sands were suspended at the lower part of the cover which was covering
the crucible with liquid metal (cast iron), placed in the induction furnace. The authors own methodology was applied in investigations. The
progressing of the samples surface layers heating process was determined as the heating time function. Samples of a few kinds of
moulding sands with chemical binders were tested. Samples without protective coatings as well as samples with such coatings were tested.
The influence of the thermal radiation on bending resistance of samples after their cooling was estimated. The influence of several
parameters such as: time of heating, distance from the metal surface, metal temperature, application of coatings, were tested. A very fast
loss of strength of moulding sands with organic binders was found, especially in cases when the distance between metal and sample
surfaces was small and equaled to 10÷15 mm. Then, already after app. 15 seconds of the radiation (at Tmet=1400o
C), the resistance
decreases by nearly 70%. Generally, moulding sands with organic binders are losing their strength very fast, while moulding sands with
water glass at first increase their strength and later slightly lose. The deposition of protective coatings increases the strength of the mould
surface layers, however does not allow to retain this strength after the metal thermal radiation.
The thermal reclamation process as a utilisation method of spent moulding and core sands is more costly than other reclamation methods, but in the majority of cases it simultaneously provides the best cleaning of mineral matrices from organic binders. Thus, the application of the thermal analysis methods (TG-DSC), by determining the temperature range within which a degradation followed by a destruction of bounded organic binders in moulding sands, can contribute to the optimisation of the thermal reclamation process and to the limiting its realisation costs. The thermal analysis results of furan resin, one of the most often applied binder in foundry practice, are presented in the hereby paper. The influence of the heating rate of the sample - placed in the thermal analyser - on its degradation and destruction process under oxygen-free (argon) and oxygen (air) conditions, were compared. The recorded TG and DSC curves were used for analysing these processes as the temperature as well as the time function. The obtained results were analysed with regard to determining the required temperature of the thermal reclamation of the investigated organic binder. The usefulness of the developed methodology was found out, however under conditions of meeting several essential requirements concerning the repeatability of performed analyses.
The paper presents the statical research tests of rod bolt made of plastic with a length of 5.5 m, which were performed in a modern laboratory test facility at the Department of Underground Mining of the University of Science and Technology. Innovative The Self-excited Acoustic System (SAS) used to measure stress changes in the bolt support was characterized. The system can be used for the non-destructive evaluation of the strain of the bolt around the excavations as well as in tunnels. The aim of the study was to compare the re-sults recorded by two different measuring systems, thanks to which it will be possible to assess the load of long bolt support by means of the non-destructive method. The speed and simplicity of measurement, access to the sensors, accuracy of measurement and reading should be kept in mind in determining the load of rock bolt support . In addition, the possibility of damage to the sensor as a re-sult of technological or natural hazards should also be taken into account. In economic conditions, the „technical - balance laws of production”, which ex-cludes the use of load sensors on each bolt must be preserved. The use of indi-vidual load sensors of rock bolt support for the boundary state, allows appro-priate protection actions of the mining crew against sudden loss of excavation stability to be taken. The paper presents two basic effects used in the ultrasonic measurement sys-tem. The first result was the existence of stable limit cycle oscillations for posi-tive feedback. This effect is called the self-excited effect. The second effect is called the elasto-acoustic effect. It means that with the change of elastic stress-es in the material bring the change of the speed of propagation of the wave. In this connection, the propagation time between measuring heads is also changed. This effect manifests itself in the change in the oscillation frequency of the self-excited system. For this reason, by measuring the frequency of self-excited oscillation, it is possible to indirectly determine the level of effort of the tested material.
This paper describes the simulation, exergy analysis and comparison of two commonly applied liquefaction of technologies natural gas, namely: propane precooled mixed refrigerant process (C3MR) and dual mixed refrigerant process (DMR) alongside two modifications of each employing end flash systems. The C3MR and DMR process schemes were simulated using the commercial software to mathematically model chemical processes. These schemes were then analysed using energy and exergy calculations to determine their performances. The exergy efficiency for the C3MR processes without end flash system, with simple end flash system and extended end flash system were evaluated as 29%, 31%, and 33%, respectively, while the exergy efficiency for the DMR processes without end flash system, with simple end flash system, and extended end flash system were evaluated as 26%, 25.5%, and 30%, respectively. The results achieved show that the extended end flash system versions of the schemes are most efficient. Furthermore, the exergy analysis depicted that the major equipment that must be enhanced in order to improve the cycle exergy efficiencies are the compressors, heat exchangers, and coolers.
Ecology and life characteristics of overwintering larvae of the European corn borer (Ostrinia nubilalis Hbn.) (Lep.: Crambidea) are partly unexplored due to their hidden lifestyle. In plant protection research the best way to study these phenomena is to apply less used, non-destructive, in vivo methods. The objective of our CT survey was to examine the factors influencing the location of the overwintering O. nubilalis larvae in maize stalks. The findings obtained by CT-analysis can be used for monitoring the presence and location of O. nubilalis larvae in the stalk, as well as both their displacement and movement. Our results showed that both the location and the distance from the brace root of O. nubilalis larvae were significantly influenced by the sampling time, the number of larvae per plant, the stalk diameter and finally the prevailing temperature. The location of the larvae situated nearest to the brace roots (first larvae) was significantly lower in stalks containing several larvae, than those where only a single larva was found in the stalk. The thickness of stalks was related to the simultaneous presence of more larvae, and to the ground level position of the first larvae. These overwintering larvae were located closer to the brace root (and to the soil), possibly because of having moved downwards inside the stalk, where the temperature is slightly milder than in the upper part of the stalk.
The paper presents a 3D model and simulations of corroding reinforcement bars in a concrete element. Electric potential distributions are calculated in the concrete matrix and on its surface for two rebars arrangements with one or three active (anodic) sites to assess the reliability and identify possible problems when standard test measurements for corrosion assessment in concrete structures are used and conclusion on the corrosion state is inferred. The values of the potential strongly depend on a concrete layer thickness and beyond the threshold of 5-7 cm it is hardly possible to detect the number of active sites on the rebar. Also conductivity – which is not constant in real world constructions – is an important factor. Thus without estimation of the state of concrete it is difficult to draw reliable conclusions on the corroding activity from shear potential measurements on the surface.
In 1875 a steel railway bridge was built in northern Warsaw. It had seven spans of 66.22 m and two spans of 15.24 m. In 1908 the second railway bridge was built downstream of the older one. The spacing of supports and spans were the same as in the older bridge. During World War I, both bridges were blown up and then rebuilt, first temporarily and then permanently. Again both were blown up in 1944. In 1945, a temporary crossing was built. In 1947 a permanent bridge was rebuilt, partially replacing rivets with welding. On the pillars of the older bridge, the Gdański Bridge was built (not in this study). In 1963 welded connections were strengthened, in 1980 the structure of the northern track was replaced. In 2016, the northern track was renovated. The replacement of the structure of the southern track is ongoing since 2018.
Efficiency and electrical power output of combined cycle power plants vary according to the ambient conditions. The amount of these variations greatly affects electricity production, fuel consumption, and plant incomes. Obviously, many world countries have a wide range of climatic conditions, which impact the performance of power plants. In this paper, a thermodynamic analysis of an operating power plant located in Jordan is performed with actual operating data acquired from the power plant control unit. The analysis is performed by using first and second laws of thermodynamics. Energy and exergy efficiencies of each component of the power plant system are calculated and the effect of ambient temperature on the components performance is studied. The effects of gas turbine pressure ratio, gas turbine inlet temperature, load and ambient conditions on the combined cycle efficiency, power outputs and exergy destruction are investigated. Energy and exergy efficiencies of the combined cycle power plant are found as 45.29%, and 42.73% respectively when the ambient temperature is 34 ◦C. Furthermore, it is found that the combustion chamber has the largest exergy destruction rate among the system components. The results showed that 73% of the total exergy destruction occurs in the combustion chamber when the ambient temperature is 34 ◦C. Moreover, the results show that the second major exergy loss is in HRSC. The results show that the energy and exergy efficiency of the combined cycle power plant decreases as the ambient temperature increases. According to the calculation results, improvement and modification suggestions are presented.
The paper presents an example of the application of vibratory machining for castings based on the results of visual testing. The purpose of the work is to popularize non-destructive testing and vibratory machining as finishing process, especially in the case of cast objects. Visual testing is one of the obligatory non-destructive tests used for castings and welded joints. The basic requirements concerning the dimensional accuracy and surface texture of cast components are not met if visible surface flaws are detected. The tested castings, which had characteristic traces of the casting process, were subjected to vibratory machining. The machining with loose abrasive media in vibrating containers is aimed at smoothing the surface and reducing or completely removing flashes. To complement the visual testing were also conducted research on the contact profilometer Taylor Hobson PGI 1200. Particular attention was focused on measuring the height of flashes and changes in the surface of smoothed details based on BNIF No. 359 touch-visual patterns. Based on the work, it can be concluded that vibratory machining allows for removal flashes and smoothing of the surface of aluminum alloy cast objects.