A contrast between classical method and finite element method for calculating strength in impeller of centrifugal pump

In order to calculate accurately the stress and the deformation conditions of the closed impeller of centrifugal pumps in the flow field, “direct-calculation method” and the ANSYS Workbench-based finite element method are separately used to calculate the maximum stress that the impeller bears and the strength check of it have been proceed. This paper has made a comparative analysis between the two methods, and it is shown that the finite element analysis method can more comprehensively show the stress concentration, whereas the traditional method is more focused on the average of checking. Therefore, in terms of the results, it is suggested that in addition to the traditional direct-calculation method, modern simulation software such as the finite element method should be used for the proofread of the impeller in the industry, in order to improve the running safety and the reliability of the closed impeller of centrifugal pumps

Modelling the electromagnetic separation of non-metallic particles from liquid metal flowing through a two-stage multichannel

A two-stage multichannel was designed to increase the efficiency of separating non-metallic particles from liquid metal flowing through an alternating magnetic field. Numerical method was developed to calculate the particle concentration and separation efficiency of a zinc melt containing dross particles and verified by the experimental results. The distribution of particle concentration and axial fluid velocity changed significantly due to the added walls in the sub-channel, resulting in an abrupt increase in the residence time of the inner bulk melt with high particle concentrations and a remarkable increase in particle separation efficiency when flowing through the single-channel to sub-channels. A multistage and multichannel arrangement is hence recommended for further increase in the separation efficiency of an electromagnetic separator

Tailoring hierarchical microstructures and nanoprecipitates in additive-manufactured Al-Zn-Mg-Cu-Nb alloys for simultaneously enhancing strength and ductility

Additive manufacturing provides an efficient way of producing metallic components with complex geometries. Their microstructure is substantially different to those from conventional processing, creating opportunities for manipulating the final microstructure and properties via heat treatment. Here, we demonstrate that as-built heterostructures in an Al-Zn-Mg-Cu-Nb alloy produced during the solidification of molten pools provide a driving force and additional Zener pinning sources for recrystallization. This creates a bimodal grain structure after solution treatment, causing additional hetero-deformation-induced strengthening and hardening. Coarse grains are found to promote work hardening and blunt the propagate of cracks during deformation, increasing ductility. Together with precipitation strengthening from a high number density nanoprecipitates, the simultaneous improvement of strength and ductility in a highly alloyed Al-Zn-Mg-Cu-Nb alloy is achieved. These results provide a simple strategy for the development of additively manufactured age-hardening alloys with improved strength and ductility for high performance structural applications

Impact of High, Low, and Non-Optimum Temperatures On Chronic Kidney Disease in a Changing Climate, 1990-2019: a Global analysis

BACKGROUND: Although a few studies have reported the relationship between high and low temperatures and chronic kidney disease (CKD), the global burden of CKD attributable to extreme heat and cold in recent decades remains unknown. METHODS: Based on the Global Burden of Disease Study (GBD) 2019, we obtained data on age-standardized mortality rates (ASMR) and age-standardized rates of disability-adjusted life years (ASDR) per 100 000 population of the CKD attributable to non-optimum temperatures from 1990 to 2019. The annual mean temperature of each country was used to divide each country into five climate zones (tropical, subtropical, warm-temperate, cool-temperate, and boreal). The locally weighted regression model was used to estimate the burden for different climate zones and Socio-demographic index (SDI) regions. RESULTS: In 1990, the ASMR and ASDR due to high temperature estimated -0.01 (95% UI, -0.74 to 0.44) and -0.32 (-21.66 to 12.66) per 100 000 population, respectively. In 2019, the ASMR and ASDR reached 0.10 (-0.28 to 0.38) and 2.71 (-8.07 to 10.46), respectively. The high-temperature burden increased most rapidly in tropical and low SDI regions. There were 0.99 (0.59 to 1.39) ASMR attributable to low-temperature in 1990, which increased to 1.05 (0.61-1.49) in 2019. While the ASDR due to low temperature declined from 22.03 (12.66 to 30.64) in 1990 to 20.43 (11.30 to 29.26) in 2019. Overall, the burden of CKD attributable to non-optimal temperatures has increased from 1990 to 2019. CKD due to hypertension and diabetes mellitus were the primary causes of CKD death attributable to non-optimum temperatures in 2019 with males and older adults being more susceptible to these temperatures. CONCLUSIONS: The CKD burden due to high, low, and non-optimum temperatures varies considerably by regions and countries. The burden of CKD attributable to high temperature has been increasing since 1990

Evaluation of Trichogramma ostriniae (Hymenoptera: Trichogrammatidae) as a biological control agent against the European corn borer, Ostrinia nubilalis (Lepidoptera: Pyralidae): Biological, behavioral and ecological perspectives

The biology and behavioral ecology of Trichogramma ostriniae, an introduced egg parasitoid of Ostrinia nubilalis and other lepidopteran species were studied in the laboratory and under field conditions. The inter- and intra-specific discrimination, competition, and the effectiveness of T. ostrinia and T. nubilale were also investigated. For T. ostriniae to complete its life cycle, it took 6.7 days at 33\sp\circC and 20 days at 17\sp\circC. Comparison of several theoretic models indicated that a transformed day-degree model and the Hilbert-Logan model were better for predicting the development of this parasitiod. The wasps reared on O. furnacalis by the seventh generation and at 27\sp\circC had a lower level of parasitism than wasps from other generations and at other temperatures. The differences among generations for the time female wasps spent drumming host eggs did not show any host and generation related trend. European corn borer egg parasitism was positively correlated with egg density. Female T. ostriniae might exhibit the Type II or Type III functional response depending on the temperature. The field data suggested a Type II functional response when data were pooled for all replicates. The effects of weather, plant size, and distribution of egg masses on egg parasitism by the wasp were studied in a sweet corn field. Logistic regression analyses indicated that percentage of eggs parasitized was negatively related to an increase in leaf area and distance of eggs from release point. Eggs on leaves in the upper third of a corn plant received much less parasitism than those on the middle and lower third. Temperature as well as the length of exposure of egg to wasps also affected the level of egg parasitism. Laboratory test on the cross breeding between T. ostriniae and T. nubilale indicated no successful hybridization. The results of the inter- and intra-specific discrimination and competition between the two species revealed that only female T. ostriniae discriminated eggs parasitized by females of the same species. When both species oviposited the same egg, T. ostriniae was most likely to be able to complete development. The level of egg parasitism by releasing T. ostriniae alone was found to be 15% higher than that by releasing T. nubilale alone, and 20% higher than by releasing a combination of the two species. Further analyses using the logistic regression model for independent and correlated data indicated T. ostriniae to be more efficient at discovering host egg masses than T. nubilale. Mutual interference between the two species was the main factor for the lower level of egg parasitism when the two species were released together. The results suggest that T. ostriniae is the better candidate for augmentative releases for control of the European corn borer, and the two species should not be released into a corn field at the same time

Maximal Function Characterizations of Hardy Spaces on Rn with Pointwise Variable Anisotropy

In 2011, Dekel et al. developed highly geometric Hardy spaces Hp(Θ), for the full range 0&lt;p≤1, which were constructed by continuous multi-level ellipsoid covers Θ of Rn with high anisotropy in the sense that the ellipsoids can rapidly change shape from point to point and from level to level. In this article, when the ellipsoids in Θ rapidly change shape from level to level, the authors further obtain some real-variable characterizations of Hp(Θ) in terms of the radial, the non-tangential, and the tangential maximal functions, which generalize the known results on the anisotropic Hardy spaces of Bownik.</jats:p