4,896 research outputs found
Hopper discharge of cohesive powders using pulsated airflow
No full textAn aerated hopper with pulsated aeration was designed to study the effect of square‐wave pulsated airflow on the discharge characteristics of cohesive and non‐cohesive powders. Experiments were carried out with pulsation frequencies between 0 (continuous) and 50Hz. Two flow patterns were observed at different aeration rates and pulsation frequencies: intermittent and smooth. For non‐cohesive powders, pulsated aeration has a worsening effect on discharge flow. For cohesive powders, results revealed that pulsated aeration can reduce the minimum aeration necessary to allow continuous discharge. And the maximum discharge rate that can be attained applying pulsated aeration is higher than that of continuous aeration and it is significantly more uniform. The aggregates size of the powder was estimated and used to understand the stabilizing mechanism of pulsated aeration on the aggregative discharge. The model value of the minimum aeration rate and the discharge rate were obtained and compared with the experimental values
Study on fine powder discharged from hoppers modified with insert
No full textThe use of inserts in the hopper provides a reliable way to improve the quality of powder flow. In this work, glass beads, fluidized catalytic cracking catalyst (FCC), lignite and polyvinyl chloride (PVC) were used as experimental materials and the flow properties of powders were characterized by the FT4 powder rheometer and the PT-X powder tester. Discharge experiments on a Perspex hopper at a laboratory scale are presented in this paper, comparing the flow characteristics of fine powders discharged from a plain hopper and from hoppers modified with the use of inserts of different geometries. Effects of insert and powder properties on powder flow rate are discussed. A mechanism model is developed to describe the hindering effect to the discharge consequent to the powder expansion at the hopper outlet. Mechanisms of insert on powder flow are analyzed. It is demonstrated that the higher flow rates of the hopper operating with a solid insert are due to the anticipated expansion of the material generated by the presence of the insert. The hopper with a hollow insert shows a flow sequence and the values for the powder flow rates are averaged values between two regimes. Based on understanding above mechanisms, powder flow rates for plain hopper and hoppers modified with insert are successfully predicted
sj-xlsx-1-jis-10.1177_01655515231174385 – Supplemental material for Citation advantage of COVID-19-related publications
No full textSupplemental material, sj-xlsx-1-jis-10.1177_01655515231174385 for Citation advantage of COVID-19-related publications by Weishu Liu, Xuping Huangfu and Haifeng Wang in Journal of Information Science</p
sj-rar-1-jef-10.1177_15589250221121843 – Research Data for Optimization analysis of combing box for air yarn based on computational fluid dynamics
No full textResearch Data, sj-rar-1-jef-10.1177_15589250221121843 for Optimization analysis of combing box for air yarn based on computational fluid dynamics by HaiFeng Fang, HanLin Sun, Qun Liu, Rui Liu and MingQiang Wang in Journal of Engineered Fibers and Fabrics</p
Numerical investigation of novel FRP composites towards high-strength, large-deformation, and tensile-behavior designable properties
No full textA FRP composite consisting of FRP skins, 3D printed inner cores and twisted knots has been developed to achieve low-density, high-strength, large-deformation, and tensile-behavior designable properties. Desired nonlinear responses could be achieved by loading FRP skins to plastically deform inner cores with carefully designed configurations. However, current investigations provided few computational tools for determining the tensile behavior of the composite with various core configurations. In this study, a two-dimensional finite element (FE) model has been calibrated for the composite having various brace thicknesses, shell thicknesses, core spans, core heights, brace angles, and core numbers. Predictions were compared with experimental measurements in terms of entire stress-strain shapes, ultimate stresses and strains. Good correlation between predictions and corresponding measurements validate the reliability of the proposed FE model. By using the proposed FE model, a more sophisticated and efficient FRP composite could be developed upon increasingly updated demands.</p
Numerical studies on the entire debonding propagation process of FRP strips externally bonded to the concrete substrate
No full textDebonding of FRP strips from concrete substrate is an important issue in FRP-strengthened concrete structures. While a great number of expressions have been published to determine the strength of the FRP-concrete bond, few closed-form solutions are available to well predict the entire load displacement responses. This paper has numerically studied the full-range behavior of FRP strips debondingfrom concrete substrate by using Finite Element (FE) predictions which show good correlation with experimental results. Based on the numerical predictions, solutions have been developed to describe the load-displacement responses at each loading stage. The impacts of the strip width, the bond length, the thickness and the elastic modulus of FRP strips on the proposed solutions have been discussed. The proposed solutions show good accordance with the experimental results and the numerical predictions, indicating its reliability in predicting the interfacial behavior of FRP-concrete bond
Climate and edaphic factors drive soil nematode diversity and community composition in urban ecosystems
No full textRapid urbanization profoundly affects global biodiversity. How urbanization modifies soil biodiversity and perturbs nematodes remains limited. Here, we investigated soil nematodes in four land-use types: Parks, residential areas, natural forests, and maize fields across 12 cities in China. Urban parks and surrounding forests had similar nematode richness exceeding that in urban residential areas and surrounding farmlands. Nematode
communities in parks and residential areas were, however, more homogenous than in forests and farmlands. Variations in nematode assemblages in both core urban and urban surroundings were mainly due to taxa replacement, indicating that nematodes were spatially isolated in cities. Urban residential areas were colonized by the lowest number of specialists (i.e., with narrow niche width) and smaller body sizes. Urban parks, conversely, served as hotspots for soil nematodes in cities. Together, our results indicate that urbanization processes reduce nematode diversity, with e.g., 30% loss in residential areas compared to forests, and homogenize soil nematode communities
Supplemental Material - Endoscopic Lumbar Interbody Fusion, Minimally Invasive Transforaminal Lumbar Interbody Fusion, and Open Transforaminal Lumbar Interbody Fusion for the Treatment of Lumbar Degenerative Diseases: A Systematic Review and Network Meta-Analysis
No full textSupplemental Material for Endoscopic Lumbar Interbody Fusion, Minimally Invasive Transforaminal Lumbar Interbody Fusion, and Open Transforaminal Lumbar Interbody Fusion for the Treatment of Lumbar Degenerative Diseases: A Systematic Review and Network Meta-Analysis by Xijian Hu, Lei Yan, Xinjie Jin, Haifeng Liu, Jing Chai, and Bin Zhao in Global Spine Journal</p
Designing enhanced multi-dimensional constellations for code-domain NOMA
No full textThis letter presents an enhanced design of multi-dimensional (MD) constellations which play a pivotal role in many communication systems such as code-domain non-orthogonal multiple access (CD-NOMA). MD constellations are attractive as their structural properties, if properly designed, lead to signal space diversity and hence improved error rate performance. Unlike the existing works which mostly focus on MD constellations with large minimum Euclidean distance (MED), we look for new MD constellations with additional feature that the minimum product distance (MPD) is also large. To this end, a non-convex optimization problem is formulated and then solved by the convex-concave procedure (CCCP). Compared with the state-of-the-art literature, our proposed MD constellations lead to significant error performance enhancement over Rayleigh fading channels whilst maintaining almost the same performance over the Gaussian channels. To demonstrate their application, we also show that these MD constellations give rise to good codebooks in sparse code multiple access systems
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