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Number of results: 58
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Abstract

Nanotechnology has been widely applied in agriculture, and understanding of the mechanisms of plant interaction with nanoparticles (NPs) as environmental contaminants is important. The aim of this study was to determine the effects of foliar application of cobalt oxide (Co3O4) NPs on some morpho-physiological and biochemical changes of canola (Brassica napus L.) leaves. Seeds were sown in plastic pots and grown under controlled conditions. Fourteen-day-old seedlings were sprayed with different concentrations of Co3O4 NPs (0, 50, 100, 250, 500, 1000, 2000, and 4000 mg L-1) at weekly intervals for 5 weeks. Growth parameters of the shoot (length, fresh and dry weights) were stimulated by low concentrations of Co3O4 NPs (50 and 100 mg L-1) and repressed by higher concentrations. Similar trends were observed in photosynthetic pigment contents. The results indicated that high concentrations of Co3O4 NPs increased lipoxygenase (LOX) activity and the malondialdehyde (MDA), hydrogen peroxide (H2O2), and dehydroascorbate (DHA) contents, but reduced the membrane stability index (MSI), ascorbate (ASC), and glutathione (GSH). Despite the increase of antioxidant capacity (DPPH) and the accumulation of nonenzymatic antioxidants (total flavonoids and flavonols) and osmolytes (proline, glycine betaine (GB) and soluble sugars) at high concentrations of Co3O4 NPs, the growth and photosynthesis were reduced. The defence system activity did not seem to be sufficient to detoxify reactive oxygen species (ROS). Altogether, high concentrations of Co3O4 NPs showed a phytotoxic potential for canola as an oilseed crop.
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Abstract

Rare and endemic plant species represent important components of plant biodiversity which require protection to ensure their sustainable conservation. Cerastium banaticum (Rochel) Heuff. is such an endemic and rare species from Romania, for which the genetic variability of two natural populations was studied by SSR markers. Shannon’s information index revealed low levels of genetic diversity in both populations (I = 0.296). As the first attempt in a conservation program a reproducible micropropagation protocol was established starting from seeds, followed by multiplication, rooting, and ex vitro acclimatization. Among the various plant growth regulators tested the highest multiplication coefficient was achieved on a culture medium with 0.5 mg L-1 6-furfurylaminopurine (K) and 1 mg L-1 α-naphthaleneacetic acid (NAA). On this PGRs concentration a number of 26.6 shoots/individual explant with a mean length of 7.9 cm for new generated shoots was registered. The highest number of roots/individual initiated shoot was 2.6 and it was recorded on a culture medium with 0.5 mg L-1 2-isopentyl-adenine (2iP) and 0.1 mg L-1 NAA. The outdoor acclimatization was successfully performed in a specially designed rocky area in the ‘Alexandru Borza’ Botanical Garden, Cluj-Napoca (Romania).
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Abstract

The article is a case study of the steel milling ring casting of about 6 tonnes net weight. The casting has been cast in the steel foundry the authors have been cooperating with. The aim was to analyse the influence of the shape of the chills and the material which was used to make them on the casting crystallization process. To optimally design the chills the set of the computer simulation has been carried out with 3 chills’ shape versions and 3 material’s versions and the results have been compared with the technology being in use (no chills). The proposed chills were of different thermal conductivity from low to high. Their shapes were obviously dependant on the adjacent casting surface geometry but were the result of the attempt to optimise their effect with the minimum weight, too. The chills working efficiency was analysed jointly with the previously designed top feeders system. The following parameters have been chosen to compare their effectiveness and the crystallization process: time to complete solidification and so-called fed volume describing the casting feeding efficiency. The computer simulations have been carried out with use of MagmaSoft v. 5.2 software. Finally, the optimisation has led to 15% better steel yield thanks to 60% top feeders weight reduction and 40% shorter solidification time. The steel ring cast with use of such technology fulfil all quality criteria.
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Abstract

One of the biggest problems for sand casting foundries must be the waste produced from disposable molds. Stricter environmental regulations make it harder to dispose of waste sand, so a truly competitive foundry does no longer only make great products, but also concentrates on a sustainable casting process. While methods for repurposing waste foundry sand are still limited, the internal circulation of such sands proves significant possibilities. This paper will focus on thermal reclamation of foundry sands in a special rotating drum furnace in a central facility to serve several foundries. Thermal reclamation is a process for handling foundry sands in elevated temperatures to combust unwanted substances from reusable base sand. The introduction focuses on background of the Finnish foundry business, the most common sand systems in Finland and their reclaim properties. The experimental part features presentation of the new reclamation plant process and the conducted test runs. The samples collected from each test run have been laboratory tested to assure proper sand quality. The results of this work showed that the reclamation of alkaline phenolic no-bake sands was excellent. Reclamation of green sands did not provide satisfactory results as expected and the reclamation of furan no-bake sands provided mixed results, as the raw material was imperfect to begin with. The most important result of this work is still the successful initiation of a centralized thermal reclamation plant, with the ability to reclaim sands of several foundries. With this all of industrial symbiosis, circular economy and sustainability advanced in Finland, and the future development of this plant provides even further opportunities and a possibility to spread the ideas on a global scale.
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Abstract

Image analysis allows to acquire a number of valuable quantitative informations on the observed structure and make appropriate conclusions. So far, a large part of analyzed images came only from light microscopes, where it was a possibility of accurately distinguish the different phases on the plane. However, the problem happened in the case of the observation of images obtained by scanning electron microscopy. In this case, the presence of various shades of gray, and the spaciousness of the image attained. To perform the analysis the matrix images of the ausferritic ductile iron were used. Full analysis was carried out using the computer program MicroMeter 1.03. Results obtained in the analysis were related directly to the results from X-ray diffraction. Obtained as a result of the analysis were related directly to the results from X-ray diffractometer. The following technique has weaknesses, including the misinterpretation by the operator microscope or program. After all, it was possible to obtain similar results to the result that has been obtained from X-ray diffractometer.
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Abstract

The article presents results of studies of silicon – molybdenum cast iron (4.42% Si, 2.59% Mo and 2.48% C wt.-%) crystallization process. Metallographic analysis was carried out using SEM-scanning electron microscopy with the EDS system. In order to determine the phase composition, X-ray diffraction studies were performed. Thermo-Calc, a computer simulation program, was used to simulate the crystallization process. . The obtained data allowed to describe the effect of some elements on the crystallization process. The silicon phase of MnSi could not be identified during metallographic studies. Also, computer simulation of the crystallization process did not answer the question at which point the silicon phase of MnSi crystallizes in the tested alloy. Therefore, not all results obtained were linked to the registered crystallization process (TDA process). The EDS analysis revealed an unusual distribution of molybdenum in the microstructure of the sample, where it is clearly visible that the area enriched with this element is also the separation of spheroidal graphite. The possibility of occurrence of Mo-rich micro-areas found in graphite is considered. The case is debatable and difficult to resolve at this stage. Perhaps, at such a high concentration of molybdenum (2.59% Mo) in the alloy, conditions are created for simultaneously crystallization of graphite and molybdenum phases.
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Abstract

In this study, the modification mechanism and growth process of Al3(Sc, Zr) particles in as-cast Al-Si-Mg-Cu based alloy with addition of Sc and Zr were systematically investigated. It was found that 0.57 wt-%Sc addition caused a significant refinement in the average grain size of the investigated alloy, which brought about a remarkable transformation in as-cast microstructure, from thick dendritic shape to fine equiaxed structure. A large amount of primary Al3(Sc, Zr) particles with the dimension of around 5-6 μm were also observed within the equiaxed grain. Due to the identical orientation and similar crystal structure between primary Al3(Sc, Zr) particles and α-Al matrix, the primary particles always served as heterogeneous nucleus for the α-Al matrix. In addition, these cusped cubic primary Al3(Sc, Zr) particles showed triangle, star, rhomboid morphologies are generated from sectioning the particle in (111), (100) and (110) planes, respectively. Particularly, the typical eutectic structure which contained odd number-layer (Al3(Sc, Zr)+α-Al+  +Al3(Sc, Zr)) was observed within the investigated particles.
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Abstract

Morocco is basically an agricultural country; almost 40% of the workforce is employed in this sector. Xylella fastidiosa is a xylem-inhabiting pathogen which can infect more than 300 plant species, although most host species are symptomless. Until relatively recently, X. fastidiosa was primarily limited to North and South America, but in 2013 a widespread epidemic of olive quick decline syndrome caused by this fastidious pathogen appeared in southeastern Italy, and later several cases of X. fastidiosa outbreaks have been reported in other European countries (France, Germany and Spain). Following these recently confirmed findings of X. fastidiosa in the European Union, this bacterium has become a serious threat to the Moroccan flora. The national phytosanitary authorities have adopted several measures to prevent the introduction of X. fastidiosa into the national territory by deciding, inter alia, to suspend importation of host plant species to the bacterium from infected areas. This paper presents the phytosanitary risk of this bacterium in Morocco.
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Abstract

Use of welding technology for the repair of steel castings is particularly common in two areas. These include weld surfacing of protrusions that remained incomplete after casting, or filling the surface defects (cavities). These defects are more common for steel casting than for graphite cast iron, due to the lower fluidity of steel. This article describes a suitable technological process of repairing the defects on the casting using the welding technology. A specimen produced for this purpose was prepared by carving a groove into a cast steel plate 20 GL, which was then filled with a weld metal using MAG (135) technology. The following evaluation of the basic characteristics of the repaired site point to the suitability of the selected technological parameters of the repair procedure. Metallographic evaluation was carried out, further evaluation of mechanical properties by tensile test, bend test and Vickers hardness test. The proposed methodology for the evaluation repair of foundry defects in steel castings also meets the requirements for the approval of welding procedures in accordance with the relevant valid legislation.
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Abstract

In this work, the effect of the microstructure on corrosion behavior of selected Mg- and Al-based as cast alloys, was evaluated. The electrochemical examinations were carried out, and then a morphology of corrosion products formed due to local polarization on materials surface, was analyzed. It was documented that the presence of Mg2Si phase plays an important role in the corrosion course of Mg-based alloy. A selective etching was observed in sites of Mg2Si precipitates having “Chinese script”- like morphology. Analogous situation was found for Al-based alloy, where the key role was played by cathodic θ-CuAl2 phase.
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Abstract

Iron is presented as an impurity in Al-Si alloys and occurs in the form of the β-Al5FeSi phase formations. The presence of iron and other elements in the alloy causes the formation of large intermetallic phases. Due to the high brittleness of this phase, it reduces the mechanical properties and increases the porosity. Manganese is used to inhibit the formation of this detrimental phase. It changes the morphology of the phase to polyhedral crystals, skeletal formations, or Chinese script. The present article deals with the influence of various amounts of manganese (0.1; 0.2; 0.4; 0.6 wt. %) on the formation of iron-based intermetallic phases in the AlSi7Mg0.3 alloy with different levels of iron content (0.4; 0.8, 1.2 wt. %). The increase of iron content in each alloy caused the creation of more intermetallic compounds and this effect has been more significant with higher concentrations of manganese. In alloys where the amount of 1.2 wt. % iron is present, the shape of eutectic silicon grain changes from angular to short needle type.
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Abstract

This article presents results of studies on multicriteria optimisation in the decopperisation process of flash smelting slags coming from the process of decopperisation at the "Głogów II" Copper Smelter. Measurements of viscosity were conducted using a high-temperature viscometer manufactured by Brookfield company. An addition in the form of calcium fluoride has an advantageous influence on decreasing the liquidus temperature of slag, and the effect of decreasing viscosity at the participation of calcium fluoride is significant. A motivation to conduct studies on viscosity of decopperised slags is an optimisation of the process of decopperisation at an improvement of this process parameters, i.e. the time of melt per one production cycle and consumption of electric power in the whole process. The efficiency of optimisation of the process course depends not only on an accepted criterion of the quality of controlling, a type of technological parameters, but also, to large extent, on characteristics and features of these parameters. CaCO3 currently added to the process of decopperisation efficiently decreases viscosity of flash slag, at the same time has influence on an increase of the yield of copper in alloy, but on the other hand, it increases the mass of slag, artificially under representing concentration of this metal. The article is completed with a conclusion of discussed issues, stating that a search for a new technological addition is still necessary,
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Abstract

Archaeometallurgical investigations presented in this work focus on analysing the microstructure as well as mechanical properties of artefacts from the17th in form of findings performed from cast iron as well as copper casts. The presented research results extend the up-to-date knowledge and present the analysis of structural compounds found in the microstructure of the artefacts from the time dating back to the late Middle Ages in the region around Czestochowa, Poland. The tested samples were found in earth in the city centre under the present marketplace. The excavation works were carried out in summer in the year 2009, and have resulted in the excavation of artefacts in form of copper block of the weight of several kg. The excavation action was led by a group of Polish archaeologists collaborating with the local authorities. The performed pre-dating of this element determines the age of the artefacts as the 17th century AD. The excavations that have been taking place since 2007 have widened the knowledge of the former Czestochowa. Historians of this town have suggested, that the found weight and traces of metallurgical activity suggest that the exposed walls were an urban weight. The weight is visible on the 18th century iconography. What was find on the Old Market indicates that there was a lush economic life before the Swedish invasion in this part of Poland. Some buildings lost their functions or were changed, others died in fires, but new places developed. To describe the microstructure, with its structural components, research was done using microscopy techniques, both of the light as well as electron microscopy (SEM), also chemical composition analysis was carried out using the EDS technique, as well as tool for phase analysis were applied in form of X-Ray Diffraction (qualitative analysis), especially for the reason to describe the phases present in the excavated material. This research will help to obtain new information in order to investigate further archaeometallurgical artefacts, extending the knowledge about middle age metallic materials its usage and manufacturing.
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Abstract

The paper presents results of a study on the effect of the flux density of heat carried away for the remelting area to substrate in the course of surface remelting with concentrated heat stream on values of structural parameters λ1D and λ2D of α(Al) phase dendrites in C355 alloy. The remeltings were made with the use of GTAW method, at arc current intensity I = 200 A and concentrated heat stream scanning speed vs = 200, 400, 600, and 800 mm/min. The used protective gas was argon supplied at rate of 20 l/min. It has been found that the increase of the rate of scanning with concentrated heat stream results in a change of the remelting-substrate separation surface shape consisting in reduction of the remelting width and depth. This increases the value of the flux density of heat transmitted from the remelting area to substrate which in turn acts in favor of reduction of structural parameters λ1D and λ2D characterizing α(Al) phase dendrites in C355 alloy.
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Abstract

The influence of a shape of graphite precipitates in cast iron on the thermal shock resistance of the alloy was initially determined. Investigations included the nodular cast iron and the vermicular one, as well as the cast iron containing flake graphite. The thermal shock resistance was examined at a special laboratory stand which allowed for multiple heating and cooling of specimens within the presumed temperature range. The specimens were inductively heated and then cooled in water of constant temperature of about 30°C. There were used flat specimens 70 mm long, 5 mm thick in the middle part, and tapering like a wedge over a distance of 15 mm towards both ends. The total length of cracks generated on the test surfaces of the wedge-shaped parts of specimens was measured as a characteristic value inversely proportional to the thermal shock resistance of a material. The specimens heated up to 500°C were subjected to 2000 test cycles of alternate heating and cooling, while the specimens heated up to 600°C underwent 1000 such cycles. It was found that as the heating temperature rose within the 500-600°C range, the thermal shock resistance decreased for all examined types of cast iron. The research study proved that the nodular cast iron exhibited the best thermal shock resistance, the vermicular cast iron got somewhat lower results, while the lowest thermal shock resistance was exhibited by grey cast iron containing flake graphite.
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Abstract

Detailed studies on the effects of pulsed laser interference heating on surface characteristics and subsurface microstructure of amorphous Fe80Si11B9 alloy are reported. Laser interference heating, with relatively low pulsed laser energy (90 and 120 mJ), but with a variable number (from 50-500) of consecutive laser pulses permitted to get energy accumulation in heated areas. Such treatment allowed to form two- Dimensional micro-islands of laser-affected material periodically distributed in amorphous matrix. The crystallization process of amorphous FeSiB ribbons was studied by means of scanning and transmission electron microscopy. Detailed microstructural examination showed that the use of laser beam, resulted in development of nanostructure in the heated areas of the amorphous ribbon. The generation of nanocrystalline seed islands created by pulsed laser interference was observed. This key result may evidently give new knowledge concerning the differences in microstructure formed during the conventional and lased induced crystallization the amorphous alloys. Further experiments are needed to clarify the effect of pulsed laser interference crystallization on magnetic properties of these alloys.
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Abstract

The study presents the results of the application of a statistical analysis for the evaluation of the effect of high-melting additions introduced into a pressure cast Al-Si alloy on the obtained level of its proof stress Rp0.2. The base Al-Si alloy used for the tests was a typical alloy used for pressure casting grade EN AC-46000. The base alloy was enriched with high-melting additions, such as: Cr, Mo, V and W. The additions were introduced into the base Al-Si alloy in all the possible combinations. The content of the particular high-melting addition in the Al-Si alloy was within the scope of 0.05 to 0.50%. The investigations were performed on both the base alloy and alloy with the high-melting element additions. Within the implementation of the studies, the values of Rp0.2 were determined for all the considered chemical compositions of the Al-Si alloy. A database was created for the statistical analysis, containing the independent variables (chemical composition data) and dependent variables (examined Rp0.2 values). The performed statistical analysis aimed at determining whether the examined high-melting additions had a significant effect on the level of Rp0.2 of the Al-Si alloy as well as optimizing their contents in order to obtain the highest values of the Al-Si alloy's proof stress Rp0.2. The analyses showed that each considered high-melting addition introduced into the Al-Si alloy in a proper amount can cause an increase of the proof stress Rp0.2 of the alloy, and the optimal content of each examined high-melting addition in respect of the highest obtained value of Rp0.2 equals 0.05%.
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Abstract

The paper presents the research results of the influence of the precipitation hardening on hardness and microstructure of selected Al-Si and Al-Cu alloys obtained as 30 mm ingots in a horizontal continuous casting process. The ingots were heat treated in process of precipitation hardening i.e. supersaturation with subsequent accelerated or natural ageing. Moreover in the range of the study it has been carried out investigations of chemical constitution, microscopic metallographic with use of scanning electron microscope with EDS analysis system, and hardness measurements using the Brinell method. On basis of obtained results it has been concluded that the chemical constitution of the investigated alloys enables to classify them into Al alloys for the plastic deformation as EN AW-AlSi2Mn (alternatively cast alloy EN AC-AlSi2MgTi) and as EN AW-AlCu4MgSi (alternatively cast alloy EN AC-AlCu4MgTi) grades. Moreover in result of applied precipitation hardening has resulted in the precipitation from a supersaturated solid solution of dispersive particles of secondary phases rich in alloying element i.e. Si and Cu respectively. In consequence it has been obtained increase in hardness in case of AlSi2Mn alloy by approximately 30% and in case of AlCu4MgSi alloy by approximately 20% in comparison to the as-cast state of continuous ingots.
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Abstract

In sand casting, Fused Deposition Modeling (FDM) printing by using Poly Lactic Acid (PLA) filament is one of the innovative foundry technologies being adopted to substitute traditional pattern making. Several literatures have reported the influence of process parameters such as raster angle and print speed on some mechanical properties of FDM-printed, PLA-prototypes used in other applications. This study investigated the effects of interior fill, top solid layer, and layer height on the compressive strength of rapid patterns for sand casting application. Different values of the process parameters were used to print the pre-defined samples of the PLA-specimens and a compression test was performed on them. The coupled effects of the process parameters on compressive strength were investigated and the optimum values were determined. Interior fill of 36%, layer height of 0.21 mm and top solid layer of 4 were found to produce a FDM-printed, PLApattern that sustained a compaction pressure of 0.61 MPa. A simulation analysis with ANSYS® to compare failure modes of both experiment and model shows a similarity of buckling failure that occurred close to the base of each specimen.
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Abstract

This paper presents matters related to production of ceramic and cast iron composite. The composite was made with the use of a foam structured ceramic insert. The tests included measuring of hardness, impact strength and resistance to abrasive wear of the composite produced. On the basis of obtaining results was stated that the use of foamed ceramic filters provides good conditions of filling a ceramic framework with molten grey or chromium cast iron. The growth of hardness of the ceramic- grey cast iron composite is ca. 60% as compared to the grey cast iron hardness. The growth of hardness of the ceramic- chromium cast iron composite is slight and does not exceed 5 % in comparison to the chromium cast iron. Introduction of the ceramic inserts deteriorates the cast iron impact strength by ca. 20 - 30 %. The use of ceramic inserts increases the resistance to abrasive wear in case of grey cast iron by ca. 13% and in case of the chromium cast iron by ca. 10 %.
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Abstract

The results of model investigations of the influence of the blowing process selected parameters on the distribution of the compaction of the core made by the blowing method, are presented in the hereby paper. These parameters were: shooting pressure, shooting hole diameter, amount and distribution of deaerating holes. Investigations were performed using the horizontal core box of the cuboidal cavity and the same core box into which inner inserts were introduced. These inserts were dividing the primary volume into three sectors differing in their direction, introduction conditions and the character of the core sand flow. As the compaction measure the apparent sand density was assumed. The density was determined in five measuring points in case of uniform cores, and in three measuring points in case of cores obtained in the core box with three separated sectors. The apparent density of the compacted core sand in the core box cavity was determined on the basis of the measurements of masses and volumes of samples cut-out from the determined core places by means of the measuring probe. Investigations were performed at three values of the working pressure equal 0.4, 0.5 and 0.6MPa for two diameters of the shooting hole: 10 and 20 mm. During tests the core box deaeration, controlled by an activisation of the determined number of deaerating vents placed in the core box, was also subjected to changes.
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Abstract

Light weight, low density with high mechanical properties and corrosion resistance, aluminum is the most important material and is commonly used for high performance applications such as aerospace, military and especially automotive industries. The researchers who participate in these industries are working hard to further decrease the weight of end products according to legal boundaries of greenhouse gases. A lot of research was undertaken to produce thin sectioned aluminum parts with improved mechanical properties. Several alloying element addition were investigated. Yet, nowadays aluminum has not met these expectations. Thus, composite materials, particularly metal matrix composites, have taken aluminum’s place due to the enhancement of mechanical properties of aluminum alloys by reinforcements. This paper deals with the overview of the reinforcements such as SiC, Al2O3 and graphene. Graphene has recently attracted many researcher due to its superior elastic modulus, high fatigue strength and low density. It is foreseen and predicted that graphene will replace and outperform carbon nanotubes (CNT) in near future.
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Abstract

Similarity assessment between 3D models is an important problem in many fields including medicine, biology and industry. As there is no direct method to compare 3D geometries, different model representations (shape signatures) are developed to enable shape description, indexing and clustering. Even though some of those descriptors proved to achieve high classification precision, their application is often limited. In this work, a different approach to similarity assessment of 3D CAD models was presented. Instead of focusing on one specific shape signature, 45 easy-to-extract shape signatures were considered simultaneously. The vector of those features constituted an input for 3 machine learning algorithms: the random forest classifier, the support vector classifier and the fully connected neural network. The usefulness of the proposed approach was evaluated with a dataset consisting of over 1600 CAD models belonging to 9 separate classes. Different values of hyperparameters, as well as neural network configurations, were considered. Retrieval accuracy exceeding 99% was achieved on the test dataset.
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Abstract

The paper presents the impact of biodegradable material - polycaprolactone (PCL) on selected properties of moulding sands. A self-hardening moulding sands with phenol-furfuryl resin, which is widely used in foundry practice, and an environmentally friendly self-hardening moulding sand with hydrated sodium silicate where chosen for testing. The purpose of the new additive in the case of synthetic resin moulding sands is to reduce their harmfulness to the environment and to increase their “elasticity” at ambient temperature. In the case of moulding sands with environmentally friendly hydrated sodium silicate binder, the task of the new additive is to increase the elasticity of the tested samples while preserving their ecological character. Studies have shown that the use of 5% PCL in moulding sand increases their flexibility at ambient temperature, both with organic and inorganic binders. The influence of the new additive on the deformation of the moulding sands at elevated temperatures has also been demonstrated.
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