Modelling of snowmelt runoff across the Himalayan Region

The Snowmelt-Runoff Model (SRM) was used to evaluate the impact of climate change on hydrological aspects of Lidder River Catchment of the Himalayan Region. It was observed that the river has an average discharge of 1082.49 cusecs. The coefficient of determination (R2) was varies in the range 0.90-0.95 during model validation period (2013-2018).The average coefficient of determination 0.926 and average seasonal volume difference (Dv) was obtained (-) 0.83%. The snow melt runoff harvested water can be used to bring 10 per cent more area under irrigation and water use efficiency which can be increased to an extent of 12-15 per cent for sustainable agriculture production in the Himalayan Region.

Calculation of tourism development income index based on finite element ordinary differential mathematical equation

China's tourism industry developed rapidly in the late 1990s, and its direct result is the continuous and rapid growth of tourism operating income. However, since 2010, China's tourism development has been slow and regional tourism development has been uneven. Even in different years in the same area, the tourism operating income shows great differences. How to select the key factor from many factors, as there is still no recognised method in the theoretical circle. This article combines the theories of econometrics, differential calculus, statistics and other related fields. Through in-depth basic research, the data required for the research is determined, and such data are substituted into the self-constructed econometric differential statistical model. Effective analysis of empirical objects is realised. At the same time, the article uses tourism operating income as an indicator and uses the analysis of variance method to calculate the average coefficient of variation of the same region in different years and different regions in the same year, analyses the trends and characteristics of China's tourism in the temporal and spatial structure, and proposes corresponding results on this basis.

Wear Behavior of a Heat-Treatable Al-3.5Cu-1.5 Mg-1Si Alloy Manufactured by Selective Laser Melting

In this study, the wear behavior of a heat-treatable Al-7Si-0.5Mg-0.5Cu alloy fabricated by selective laser melting was investigated systematically. Compared with the commercial homogenized AA2024 alloy, the fine secondary phase of the SLM Al-Cu-Mg-Si alloy leads to a low specific wear rate (1.8 ± 0.11 × 10−4 mm3(Nm)−1) and a low average coefficient of friction (0.40 ± 0.01). After the T6 heat treatment, the SLM Al-Cu-Mg-Si alloy exhibits a lower specific wear rate (1.48 ± 0.02 × 10−4 mm3(Nm)−1), but a similar average coefficient of friction (0.34 ± 0.01) as the heat-treated AA2024 alloy. Altogether, the SLM Al-3.5Cu-1.5 Mg-1Si alloy is suitable for the achievement of not only superior mechanical performance, but also improved tribological properties.

Methods for the Determination of the Heat Transfer Coefficient in Air Cooled Condenser Used at Biomass Power Plants

In the present work, its show a summary of functional relationships developed for the application of dry condensation systems to Biomass Power Plants that present difficulties with access to water for condensation. The bibliographic review reveals the limitations of the analyzed works, in terms of the development of mathematical models and empirical correlations that allow evaluating the simultaneous effects of the surrounding meteorological variables on the average coefficient of heat transfer and the effect on the environment of the use of dry condensation. The analytical study is based on the weak solutions and their correlation with experimental quantities available in research already established in the area of action, a procedure is developed for the calculation of the average coefficients of heat transfer that includes the influence of local climatologically variables, the effect of the spatial distribution of the tubes package on the refrigerant and the confined confinement in inclined components, which increase the reliability of the thermo-hydraulic analysis and suppresses the need for the use of excess areas required by current methods. The proposed models and correlations allow the preparation of a procedure, by means of which all the possible operative variants are evaluated.

Biomechanical behaviour and hyperelastic model parameters identification of sheep omasum

The function of the omasum is incompletely understood; however, the omasum plays an important role in the transport of appropriately sized feed particles from the reticulorumen to the abomasum, oesophageal groove closure, fermentation of ingesta, and absorption of water, volatile fatty acids, and minerals. The aim of this study is to evaluate the suitable hyperelastic anisotropic model based on biomechanical properties of sheep omasum. The results show that all five (5) hyperelastic models may be suitable for the evaluation of sheep omasum. The average coefficient of determination (R2) of Fung, Polynomial (Anisotropic), Holzapfel (2000), Holzapfel (2005) and Four-Fiber-Family hyperelastic models were found to be 0.79 ± 0.19, 0.95 ± 0.05, 0.92 ± 0.07, 0.93 ± 0.05 and 0.94 ± 0.03, respectively. Also, it was found that the best hyperelastic model for fitting uniaxial data of the sheep omasum was Polynomial (Anisotropic) with EI of 100.0 followed by the Four-Fiber-Family model with EI of 96.18.

High Temperature Tribological Performance of Steel/Copper Friction Pairs Lubricated With a Modified C-WS2-(Fe3O4+TiN) Nanoadditives in Non-Copper Coated Solid Wires

In this study, four kinds of nanoparticles: graphite, WS2, Fe3O4 and TiN were used as lubricating additives for steel/copper friction pairs to solve the problem of welding contact tube wear with non-copper-coated solid wire at high temperature. The single and composite nanoparticles have excellent dispersion stability in absolute ethanol under the action of the compound surfactant NaSTA+OA+PVP. The tribological test results showed that the maximum decrement with reference to the average coefficient of friction and wear volumes were measured with nanoparticle concentration in 1:1:1 ratio at 300℃. Compared with dry friction, the average friction coefficient and wear volume are reduced by 74.3% and 84.8%, respectively, which may be attributed to the formation of a stable tribo-film mainly composed of C-O, Fe2O3, WO3, TiO2, TiNxOy composite on the worn surface. Therefore, it is considered that the combined lubrication effects of the ball-bearing effect, repairing of worn surfaces and the tribo-film resulted in the lowest friction and wear.

Investigation on the Performance of Al7075 Alloy Surface Repaired by Cold Spray Coating Technology

Repairing different waste parts is an attractive issue due to the cost of repaired parts is much lower than the cost produced by conventional methods. In this study, the Al7075 aluminium alloy surface was repaired using the Ni-Zn-Al2O3 powder by the cold spray coating method. The microstructure, micro-hardness, and tribological performance of the repaired zone were determined. The microstructure of repaired zone consisted of ceramic Al2O3 particles embedded in the Ni and Zn metal matrix, similar to a lamellar structure. The average microhardness value of the repaired area was about 4.3% higher than the Al7075 substrate. Although the average coefficient of friction had increased in the repaired area, the wear rate had decreased approximately 1.3 times. As a result of the FESEM examination of the wear channels, the main wear mechanism of the Al7075 material was abrasive, while the main wear mechanism of the sample repaired with cold spray coating was determined as adhesive wear. Consequently, it increases the service life of the part, as the repaired zone with cold spray coating shows approximately 1.3 times better wear performance than Al7075.

Evaluation of Wear of Disc Brake Friction Linings and the Variability of the Friction Coefficient on the Basis of Vibroacoustic Signals

The article presents the results of friction and vibroacoustic tests of a railway disc brake carried out on a brake stand. The vibration signal generated by the friction linings provides information on their wear and offers evaluation of the braking process, i.e., changes in the average friction coefficient. The algorithm presents simple regression linear and non-linear models for the thickness of the friction linings and the average coefficient of friction based on the effective value of vibration acceleration. The vibration acceleration signals were analyzed in the amplitude and frequency domains. In both cases, satisfactory values of the dynamics of changes above 6 dB were obtained. In the case of spectral analysis using a mid-band filter, more accurate models of the friction lining thickness and the average coefficient of friction were obtained. However, the spectral analysis does not allow the estimation of the lining thickness and the friction coefficient at low braking speeds, i.e., 50 and 80 km/h. The analysis of amplitudes leads to the determination of models in the entire braking speed range from 50 to 200 km/h, despite the lower accuracy compared to the model, based on the spectral analysis. The vibroacoustic literature presents methods of diagnosis of the wear of various machine elements such as bearings or friction linings, based on amplitude or frequency analysis of vibrations. These signal analysis methods have their limitations with regard to their scope of use and the accuracy of diagnosis. There are no cases of simultaneous use of different methods of analysis. This article presents the simultaneous application of the amplitude and frequency methods in the analysis of vibroacoustic signals generated by brake linings. Moreover, algorithms for assessing the wear of friction linings and the average coefficient of friction were presented. The algorithm enables determination of the time at which the friction linings should be replaced with new ones. The final algorithm analyzes the vibration acceleration signals using both amplitude analysis for low braking speeds, as well as spectral analysis for medium and high braking speeds.

Accurate estimation of temperatures in a cryogenic space cooled by a Stirling cryocooler

The experimental analysis of cryogenic chambers coupled with Stirling cryocoolers has received scant attention in the research literature. This work provides a novel contribution by developing and experimentally validating an analytical model of the coupling to predict temperatures in the system. The paper unifies the Stirling cryocooler equation previously derived by Otaka et al. and the thermal-electrical analogy for the chamber. The analytical formula predicts steady-state temperatures in the chamber as a function of the system's controllable design and operational parameters. The model was validated with experimental data from 15 tests of an alpha-type Stirling cryocooler coupled with a thermal chamber. The resulting model showed an accurate prediction of temperatures with an average coefficient of variance of 5%, mean biased error of 2%, and R² value of 0.95. The findings are relevant because of the urgent need to learn how to control cryogenic spaces using electricity-based systems. Such spaces will be of high significance in the future because advanced solutions and products in biomedicine, electronics, computing and other fields use cryogenic spaces.

Microsatellite-Based Genetic Structure and Hybrid Detection in Alpacas Bred in Poland

This study aimed to characterize the population structure and genetic diversity of alpacas maintained in Poland using 17 microsatellite markers recommended by the International Society for Animal Genetics. The classification of llamas, alpacas, and hybrids of both based on phenotype is often difficult due to long-term admixture. Our results showed that microsatellite markers can distinguish alpacas from llamas and provide information about the level of admixture of one species in another. Alpacas admixed with llamas constituted 8.8% of the tested individuals, with the first-generation hybrid displaying only 7.4% of llama admixture. The results showed that Poland hosts a high alpaca genetic diversity as a consequence of their mixed origin. More than 200 different alleles were identified and the average observed heterozygosity and expected heterozygosity values were 0.745 and 0.768, respectively, the average coefficient of inbreeding was 0.034, and the average polymorphism information content value was 0.741. The probability of exclusion for one parent was estimated at 0.99995 and for two parents at 0.99999.