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关键词： Robust foil regenerator   Flow loss   Heat transfer   Experiment   Figure of merit  

摘要： A regenerator works as an energy storage component in a Stirling engine. Thus, it is one of the most critical components that makes the Stirling engine highly efficient. Traditionally, the regenerators are made of wire media such as woven screens and random fibers. These wire regenerators experience considerably high flow losses through the regenerator due to the flow separation and the resulting vortices. The high flow losses associated with the flow separation and vortices result in a lower engine efficiency. This research is to test a new robust foil regenerator to investigate its feasibility for free-piston Stirling engine applications. The robust foil regenerator is configured with parallel flow channels and stiffening ribs. Comparing to complex flows patterns in woven screen and random fiber regenerators, the flows in the parallel plates are simple and the flow losses are considerably small, and the heat transfer coefficient is also relatively small. To test the regenerator experimentally, a regenerator test rig was manufactured. To verify the accuracy of the test rig, a woven screen regenerator was made and tested prior to the robust foil regenerator test. The friction factor correlation of the woven screen regenerator shows a good agreement with the published regenerator correlations. The robust foil regenerator tests were conducted under the oscillating flow condition with different Reynolds numbers. The flow losses were measured with dynamic pressure transducers and the friction coefficient was derived from measured pressure drop. The measured temperature difference over the regenerator was used to calculate the heat transfer coefficient and Nusselt number. The figure of merit with two methods of NPH/NTU ratio and j/f ratio was calculated to evaluate the suitability of the robust foil regenerator. The results show that the robust foil regenerator has considerably higher figure of merit and therefore, better performance than other types of regenerator.

关键词： canine   CD4-CD8-   CD8+   flow Cytometry   lymphoma   T-cell  

摘要： Canine T-cell lymphoma (TCL) encompasses a heterogeneous group of diseases with variable clinical presentation, cytomorphology, immunophenotype, and biologic behaviour. The most common types of TCL in dogs involving peripheral lymph nodes include indolent T-zone lymphoma (TZL) and biologically aggressive peripheral T-cell lymphoma (PTCL). TCL phenotypes can be categorized by expression of the surface antigen molecules CD4 and CD8. The majority of TCL cases are CD4(+), with far fewer cases being CD8(+) or CD4(-) CD8(-). The clinical features of CD4(+) TCLs have been previously described. The less common TCL phenotypes, however, are poorly characterized with little to no information about prognosis. In this retrospective study, we describe and correlate the presenting clinical signs, flow cytometry, and outcomes of 119 dogs diagnosed with nodal, non-TZL, CD8(+) or CD4(-) CD8(-) TCL by flow cytometry. Skin lesions present at the time of diagnosis were more commonly observed in the CD8(+) TCL group. Mediastinal enlargement and/or hypercalcemia were more commonly seen in the CD4(-) CD8(-) TCL group. Dogs with either CD8(+) or CD4(-) CD8(-) TCLs had aggressive clinical disease with median overall survival (OS) times of 198 days and 145 days, respectively. In both groups, neoplastic cell size determined by flow cytometry ranged from small to large, and large cell size was associated with shorter OS times (median OS = 61 days). Cases classified as small cell had a median OS of 257 days. Expression levels of major histocompatibility complex (MHC) class II and CD5 were highly variable among cases but were not prognostically significant in this group of patients.

关键词： Jet penetration length   Fluidized bed with central jet   Particle-particle interactions   Particle diameter   Gas-particle flows  

摘要： Particle-particle interactions, quantified by particle-particle restitution coefficient (e) and particle diameter (ds) are two crucial parameters governing the flow hydrodynamics of dispersed gas-particle flows. In this work, a detailed numerical analysis has been carried out in order to get an insight into the effects of these two parameters on the jet penetration characteristics inside a bubbling gas-solid fluidized bed with a central jet. Specifically, the studies have been conducted to find out the effects of variations of these two parameters on the jet penetration length. It has been found that an increase in the value of particle diameter leads to a significant decrease in the jet penetration length for all other flow and physical properties remaining invariant. On the other hand, a gradual but substantial decrease in the jet penetration length has been observed with an increase in the values of e. Numerical investigations further reveal that there is no significant variation in the jet penetration characteristics for change in particle-wall interactions, quantified by the specularity coefficient (phi).

关键词： Intelligent systems  

摘要： Virtual models of "weak" classifiers for intelligent systems classifying the risk of recurrent myocardial infarction are considered. Bioimpedance investigation results were included in the construction of models of the risk of cardiovascular complications as an additional risk factor. Five classifiers were studied, of which four were heterogeneous. The models of heterogeneous classifiers were obtained by sequentially increasing the number of decision modules used in the classification model. Use of all decision modules in a heterogeneous classifier gave diagnostic sensitivity of 0.90 with diagnostic specificity of 0.86. When a configuration of the attribute space including only the conventional risk factors was used, the classification quality parameters were no worse than those for known risk scales for cardiovascular complications.

关键词： RFB-SG   Fluidization chamber   Numerical study   Solid bed   Energy  

摘要： A rotating fluidized bed in static geometry (RFB-SG) without slits is presented in this paper as a research objective. The concept of RFB-SG is highly beneficial in numerous industrial operations such as granular drying, particle coating, mixing, agglomeration, and combustion. In this study, a three-dimensional CFD model is developed using the commercial software ANSYS FLUENT 14.5, to investigate hydrodynamics and heat transfer characteristics of gas-solid in the vortex chamber. The analysis of the flow pattern of gas-solid and the prediction of fluidization capacity have been made, using appropriate parameters. The findings showed that the significant factors, such as inlet air velocity, solid-bed thickness, the volume fraction of solids, solids pressure, and heat transfer coefficient, influenced the reactor capacity. It is observed that the solid inventories of 300 and 500 g have been fluidized perfectly at inlet air velocities of 30 m s(-1)and 44 m s(-1), respectively. The overall operating and drying costs are found to be decreased due to the reduction in fluidization air requirements.

关键词： Unsaturated   Judgement criteria   Bernoulli's principle   Numerical analysis   Water content  

摘要： Seepage flow in unsaturated soil cannot be accurately calculated or measured using existing theories, as they consider several assumptions, and associated simulations are conducted under ideal conditions. Exact values such as velocity and pressure inside the unsaturated ground are not obvious that are often estimated by the seepage flow analysis. Those estimated values are not often corresponded to the measured values well. This study aimed to re-evaluate the conditions that well-known theories are established without any failures and aim to reduce the inconsistency for numerical analysis. Concretely, it develops a simple method to judge the inconsistency of well-known theories on geotechnical engineering in unsaturated soil by utilizing the fundamental magnitude relations of several properties and velocity terms in Bernoulli's principle. As a result, consistent and inconsistent conditions are classified, although it is estimated that continuous seepage ranges close to the piezometric head conservation equation: h = z + psi. The classification by this judgement is contributed to the estimation of the ground seepage condition using the combination of pressure head and hydraulic head difference in practical sites. Moreover, the inconsistency can be solved by assuming the local hydraulic gradient distributions. The hydraulic gradient modification is proposed by installing tentative seepage length and tentative hydraulic head for flow analysis. Finally, the local hydraulic gradient led by the proposed equations is calculated with the Mualem-van Genuchten model;the calculation results show the modified local hydraulic gradient is valid and applicable. Future works include discretization and analytical method. The criterion can immediately judge whether ground conditions and modification methods can be used for a more accurate seepage analysis in unsaturated soil.

关键词： Unified momentum equation   Monolithic   Fully Eulerian   Linear elastic solid   Stress field   Bouncing ball  

摘要： In this article, we present a fully Eulerian monolithic numerical method for simulating fluid-structure interaction problems. This method is based on the unified momentum equation approach, where the elastodynamic equation for linear elastic solids and the incompressible Navier-Stokes equation are unified into a single velocity-based momentum equation that can be solved using a proper numerical method for computational fluid dynamics. The level set method combined with a displacement field extension procedure was employed to capture the moving interfaces. Owing to the formulation scheme applied to the unified momentum equation, both the velocity and stress fields are computed for both the structure and the fluid. Therefore, this method is capable of not only simulating the dynamic interactions of a fluid and structure, but also computing the stress fields in both phases. Three problems were simulated as test examples, a falling disk in a fluid, the oscillation of a flexible rod in a channel, and a bouncing ball, and the results obtained were found to be physically realistic and in good agreement with the published data. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Circulating fluidized bed combustion fly ash   Pozzolanic activity   Hydration products   Microstructure   Si/Al dissolution concentration  

摘要： Circulating fluidized bed combustion fly ash (CFBCA) is a by-product of the coal-fired process in power plants. In this paper, the hydration characteristics of CFBCA are studied. The pozzolanic activity of CFBCA and pulverized coal combustion fly ash (PCA) at different ages was tested, the hydration products, microstructure of CFBCA-cement paste and PCA-cement paste and the elements distribution of Si, Al and Ca on the surface of fly ash particles were studied. Then the effects of pH value and SO3 content on the dissolution of active SiO2 and active Al2O3 from CFBCA and PCA were further discussed. The experimental results show that the pozzolanic activity of CFBCA is higher than that of PCA, and the surface of CFBCA is more easily corroded and the active SiO2 and active Al2O3 are easy to dissolve in the hydration process. CaO and anhydrite (CaSO4 center dot II) contained in CFBCA play an important role in promoting the dissolution of active SiO2 and active Al2O3. In addition, the loose structure of CFBCA and the low degree of polymerization of [SiO4] and [AlO6] are also one of the reasons for its higher hydration activity than PCA. Relevant research revealed the hydration mechanism of CFBCA, and provided a theoretical basis for its application in cement and concrete. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： 不干胶标签印刷   薄膜类   不干胶材料   附着力   表面张力   油墨   亲和性   标签印刷企业  

摘要： 在不干胶标签印刷过程中,油墨附着力不佳是经常遇到的问题,尤其是在薄膜类不干胶材料印刷时更容易遇到此类的问题,给工作人员乃至标签印刷企业造成极大困扰。导致油墨附着力不佳的原因有很多,比较常见的原因有材料表面张力不足、涂料(油墨)固化不足、涂料(油墨)与材料亲和性不好等。