Arrangements of symmetric products of spaces

Using the topological technique of diagrams of spaces, we calculate the homology of the union and the complement of finite arrangements of subspaces of the form $D + SP^{n-d}(X)$ in symmetric products $SP^n(X)$ where $D\in SP^d(X)$. As an application we include a computation of the homology of the homotopy end space of the open manifold $SP^n(M_{g,k})$, where $M_{g,k}$ is a Riemann surface of genus $g$ punctured at $k$ points, a problem which was originally motivated by the study of commutative $(m+k,m)$-groups.Comment: This is an updated version of the paper. In this version some results (Proposition 1.7., Theorem 1.8, Theorem 1.9, Theorem 1.11) are now reformulated in the greater generality (over integer coefficients). Moreover, we now interpret Theorems 1.8 and 1.11 as a generalization of classical Steenrod's theorem to the case symmetric products of (simple) diagrams of space

Verification of the Numerical Model of Optimized Bus Body Structure According to UN Regulation No. 66

Bus rollover is one of the most analyzed cases of accidents, having in mind the number of potential large number of injuries and fatalities. Therefore, this type of traffic accident became the object of numerous national and international standards and regulations. The aim of this paper is to investigate the possibilities of experimental verification of presented simplified model of the bus body section. For that purpose, completely new multifunctional test bench was presented. The methodology applied for the experimental part was explained. The results provided by the numerical simulation and by the experiment were presented, and appropriate analyses were performed. The key parameters needed for the experimental verification were specified. According to the result analysis, a comparative results review was presented, confirming that the experimental verification of the numerical model was fully acceptable. Also, all of the requirements prescribed by the applied methodology for the achieved results acceptance were fulfilled, providing that numerical simulation, with constant improvements, could be a powerful tool for quick and reliable bus structure analysis in design process

Lead Telluride Doped with Au as a Very Promising Material for Thermoelectric Applications

PbTe single crystals doped with monovalent Au or Cu were grown using the Bridgman method. Far infrared reflectivity spectra were measured at room temperature for all samples and plasma minima were registered. These experimental spectra were numerically analyzed and optical parameters were calculated. All the samples of PbTe doped with Au or Cu were of the “n” type. The properties of these compositions were analyzed and compared with PbTe containing other dopants. The samples of PbTe doped with only 3.3 at% Au were the best among the PbTe + Au samples having the lowest plasma frequency and the highest mobility of free carriers-electrons, while PbTe doped with Cu was the opposite. Samples with the lowest Cu concentration of 0.23 at% Cu had the best properties. Thermal diffusivity and electronic transport properties of the same PbTe doped samples were also investigated using a photoacoustic (PA) method with the transmission detection configuration. The results obtained with the far infrared and photoacoustic characterization of PbTe doped samples were compared and discussed. Both methods confirmed that when PbTe was doped with 3.3 at% Au, thermoelectric and electrical properties of this doped semiconductor were both significantly improved, so Au as a dopant in PbTe could be used as a new high quality thermoelectric material

The application of the artificial neural network in analysing the spread quality

In this paper, we introduce a new approach in food processing using an artificial intelligence. The main focus is simulation of production of spreads and chocolate as representative confectionery products. This approach aids to speed up, model, optimize, and predict the parameters of food processing trying to increase quality of final products. An artificial intelligence is used in field of neural networks and methods of decisions

Flakes product supplemented with sunflower and dry residues of wild oregano

This paper investigates the effects of simultaneous addition of sunflower (3, 6 or 9 g/100 g of sample) and dry residue of wild oregano (0.5 or 1 of sample), on the physical texture and chemical properties of corn flakes to obtain new products with altered nutritional properties. The chemometric analysis pointed at the versatile beneficial contributions of sunflower in corn flakes enriched with dry residue of wild oregano enabling the optimization of corn flakes formula. The presented data point that addition of milled sunflower in investigated corn flakes products improved nutritive properties while addition of dry residue of wild oregano improved physical characteristics of corn flakes products. Regarding quality (sample CF11, score value of 0.59) maximum scores have been obtained with the addition of 6 g/100 g of sunflower and 1 g/100 g of dry residue of wild oregano per 100 g of sample for corn flakes formulation. Production of corn flakes with addition of wild oregano residues contributed to the food waste valorisation in the food industry. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 46005 an Grant no. TR 31027

Influence of mechanical activation on functional properties of barium hexaferrite ceramics

© 2018 Elsevier Ltd and Techna Group S.r.l. Barium hexaferrite ceramics were prepared using mechanically activated mixtures of iron and barium titanate. The 60:40 mass% Fe:BaTiO3 powder mixtures were mechanically activated for different times (100–240 min) and sintered at 1100 and 1200 °C in order to determine the influence of mechanical activation of the precursor on the magnetic and dielectric properties of the resulting barium hexaferrite ceramics. The final product contained 84–89 mass% of Ba2Fe22.46O38Ti1.54 phase, with higher content corresponding to longer mechanical activation of the precursor. XRD and Raman measurements indicated that the remainder of the sample consists of leftover BaTiO3 and hematite, which was formed by the oxidation of iron during mechanical activation and sintering in air. Magnetic properties of samples sintered at 1200 °C are superior to those sintered at 1100 °C, which can be attributed to higher Ba2Fe22.46O38Ti1.54 phase content. The position of the Curie temperature in 350–420 °C temperature region is consistent with 0.8:1 ratio of Ti to Ba. Maximum magnetization was observed for samples activated for 120 min. Dielectric properties of samples sintered at 1200 °C showed a dependence on frequency, with a significant drop in relative permittivity with an increase in frequency in the low-frequency region, and relatively constant values of relative permittivity in the high-frequency region. The tangent loss showed a decrease with increase in frequency, where peaks corresponding to the resonance of the electron hopping frequency with the external field were observed in the samples corresponding to the longer mechanical activation. Dielectric properties showed relatively small changes for samples activated longer than 150 min

Hydrogen storage in a layered flexible [Ni<inf>2</inf>(btc)(en)<inf>2</inf>]<inf>n</inf> coordination polymer

© 2016 Hydrogen Energy Publications LLC [Ni2(btc)(en)2]n coordination polymer exhibits a layered two-dimensional structure with weak interaction between the layers. Correlation of experimental measurements, DFT calculations and molecular simulations demonstrated that its structural features, primarily the inherent flexibility of the layered polymeric structure, lead to improved hydrogen storage performance at room temperature, due to significant enhancement in isosteric heats of hydrogen adsorption. Volumetric measurements of hydrogen adsorption at room temperature show up to 0.3 wt.% hydrogen absorbed at 303 K and 2.63 bar of hydrogen pressure, with isosteric heats of adsorption of about 12.5 kJ mol−1. Predicted performance at room temperature is 1.8 wt.% at 48 bar and 3.5 wt.% at 100 bar, better than both MOF-5 and NU-100, with calculated values of isosteric heats for adsorption of hydrogen in 8–13 kJ mol−1 range at both 77 K and 303 K. Grand canonical Monte Carlo calculations show that this material, at 77 K, exhibits gravimetric hydrogen densities of more than 10 wt.% (up to 8.3 wt.% excess) with the corresponding volumetric density of at least 66 gL−1, which is comparable to MOF-5, but achieved with considerably smaller surface area of about 2500 m2 g−1. This study shows that layered two-dimensional MOFs could be a step towards MOF systems with significantly higher isosteric heats of adsorption, which could provide better room temperature hydrogen storage capabilities

Energy efficiency improvement by gear shifting optimization

Many studies have proved that elements of driver’s behavior related to gear selection have considerable influence on the fuel consumption. Optimal gear shifting is a complex task, especially for inexperienced drivers. This paper presents an implemented idea for gear shifting optimization with the aim of fuel consumption minimization with more efficient engine working regimes. Optimized gear shifting enables the best possible relation between vehicle motion regimes and engine working regimes. New theoretical-experimental approach has been developed using on-board diagnostic technology which so far has not been used for this purpose. The matrix of driving modes according to which tests were performed is obtained and special data acquisition system and analysis process have been developed. Functional relations between experimental test modes and adequate engine working parameters have been obtained and all necessary operations have been conducted to enable their use as inputs for the designed algorithm. The created model has been tested in real exploitation conditions on passenger car with Otto fuel injection engine and on-board diagnostic connection without any changes on it. The conducted tests have shown that the presented model has significantly positive effects on fuel consumption which is an important ecological aspect. Further development and testing of the model allows implementation in wide range of motor vehicles with various types of internal combustion engines

A Dynamic Analysis of the Cycloid Disc Stress-Strain State

The problem of internal forces that occur on the cycloid disc during the cycloid speed reducer operation so far has not been considered in a way that reflects its actual workloads and stresses in the cycloid disc itself. This paper presents a dynamic analysis of the stress-strain state of a cycloid disc by using experimental and numerical methods. The following cases of meshing are presented in the paper: a single-tooth, double-tooth, and triple-tooth meshing of the cycloid disc and the ring gear. The cycloid disc was chosen for this study because it is one of the main elements and the most critical element of the cycloid speed reducer. An experimental physical model of the cycloid disc and the meshing elements of the cycloid speed reducer was made based on a previously performed 3D CAD model. The numerical analysis of the stress-strain state of the cycloid disc was performed with the identically defined external load using the transient stress method. The paper presents a comparative analysis of the experimental and numerical results, which gives a solid insight into what is happening in the cycloid disc during the cycloid speed reducer operation. The experimental and simulation results both give the results with a deviation between 3% and 15%. After the detailed analyses, it is shown that the most critical element of cycloid speed reducer are output rollers, which need further study