494 research outputs found
An experimental study on the lateral pile–soil interaction of offshore tetrapod piled jacket foundations in sand
No full textRecently, tetrapod piled jacket (TPJ) foundations have shown considerable promise in offshore developments, due to the increases in power capacity and water depth for offshore wind turbines. This paper presents a set of centrifuge tests to look into the lateral loading behaviour of TPJ foundations in sand, with the overall load–displacement responses of the foundation as well as the soil resistance and internal forces on or within individual piles being examined carefully. Test results show that the back-row piles are more likely to be pulled out when the TPJ foundation is loaded laterally along the diagonal direction compared to when loaded along the orthogonal direction. The lateral soil resistance per unit length on the back-row pile(s) is approximately 60% of that on the front-row one(s) in the orthogonal loading case, and only about 40% in the diagonal loading case. Moreover, although the TPJ foundation is in its form a special case of pile groups, it is highlighted in the present study that the former case exhibits distinct loading behaviour from the latter case due to the typically large overturning moment encountered by the foundations for offshore wind turbines. Finally, the p-multipliers of the piles are demonstrated to be dependent on pile deflections, but independent on soil depths, and as a result, a modified pm model is proposed to provide guidance for the design of TPJ foundations in sand.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
A numerical study on the lateral loading behaviour of offshore tetrapod piled jacket foundations in clay
No full textJacket foundations for offshore wind turbines, typically having three or four latticework legs, are mainly subjected to lateral loads induced by winds, waves and currents during their service life. An accurate assessment of the bearing capacity of these foundations is of great importance in the design. This paper presents a study into the monotonic lateral loading behavior of tetrapod piled jacket foundations in undrained clay, with the complex lateral loads being simplified to an equivalent lateral load acting at a certain height of the jacket. A centrifuge testing programme was undertaken to provide high-quality validation data for the development of a three-dimensional finite element model established using ABAQUS. The key parameters investigated are the spacing and embedment of the piles, the height to which the equivalent lateral load acts and the angle between the direction of this load and the orthogonal line of the jacket in the horizontal plane. The parametric study aims to provide guidance to the optimal design of jacket piled foundations: for instance, to examine the critical pile embedment beyond which limited improvement of the bearing capacity of the foundation can be achieved and to define the most unfavorable lateral loading direction. In addition, the limitations of the commonly assumed constant p-multiplier, regardless of the lateral deflection of the pile and the depth along it, are critically discussed. Then an improved analytical model is proposed, based on the existing model used in design and the parametric study results, to quantify the variation of p-multiplier with depth and with pile deflection
Plastome phylogenomics provide new perspective into the phylogeny and evolution of Betulaceae (Fagales)
No full textBACKGROUND: Betulaceae is a relatively small but morphologically diverse family, with many species having important economic and ecological values. Although plastome structure of Betulaceae has been reported sporadically, a comprehensive exploration for plastome evolution is still lacking. Besides, previous phylogenies had been constructed based on limited gene fragments, generating unrobust phylogenetic framework and hindering further studies on divergence ages, biogeography and character evolution. Here, 109 plastomes (sixteen newly assembled and 93 previously published) were subject to comparative genomic and phylogenomic analyses to reconstruct a robust phylogeny and trace the diversification history of Betulaceae. RESULTS: All Betulaceae plastomes were highly conserved in genome size, gene order, and structure, although specific variations such as gene loss and IR boundary shifts were revealed. Ten divergent hotspots, including five coding regions (P(i) > 0.02) and five noncoding regions (P(i) > 0.035), were identified as candidate DNA barcodes for phylogenetic analysis and species delimitation. Phylogenomic analyses yielded high-resolution topology that supported reciprocal monophyly between Betula and Alnus within Betuloideae, and successive divergence of Corylus, Ostryopsis, and Carpinus-Ostrya within Coryloideae. Incomplete lineage sorting and hybridization may be responsible for the mutual paraphyly between Ostrya and Carpinus. Betulaceae ancestors originated from East Asia during the upper Cretaceous; dispersals and subsequent vicariance accompanied by historical environment changes contributed to its diversification and intercontinental disjunction. Ancestral state reconstruction indicated the acquisition of many taxonomic characters was actually the results of parallel or reversal evolution. CONCLUSIONS: Our research represents the most comprehensive taxon-sampled and plastome-level phylogenetic inference for Betulaceae to date. The results clearly document global patterns of plastome structural evolution, and established a well-supported phylogeny of Betulaceae. The robust phylogenetic framework not only provides new insights into the intergeneric relationships, but also contributes to a perspective on the diversification history and evolution of the family. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12870-022-03991-1
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No full textAbstract Hazelnut (Corylus spp.) is known as one of the four famous tree nuts in the world due to its pleasant taste and nutritional benefits. However, hazelnut promotion worldwide is increasingly challenged by global climate change, limiting its production to a few regions. Focusing on the eurytopic Section Phyllochlamys, we conducted whole-genome resequencing of 125 diverse accessions from five geo-ecological zones in Eurasia to elucidate the genomic basis of adaptation and improvement. Population structure inference outlined five distinct genetic lineages corresponding to climate conditions and breeding background, and highlighted the differentiation between European and Asian lineages. Demographic dynamics and ecological niche modeling revealed that Pleistocene climatic oscillations dominantly shaped the extant genetic patterns, and multiple environmental factors have contributed to the lineage divergence. Whole-genome scans identified 279, 111, and 164 selective sweeps that underlie local adaptation in Corylus heterophylla, Corylus kweichowensis, and Corylus yunnanensis, respectively. Relevant positively selected genes were mainly involved in regulating signaling pathways, growth and development, and stress resistance. The improvement signatures of hybrid hazelnut were concentrated in 312 and 316 selected genes, when compared to C. heterophylla and Corylus avellana, respectively, including those that regulate protein polymerization, photosynthesis, and response to water deprivation. Among these loci, 22 candidate genes were highly associated with the regulation of biological quality. Our study provides insights into evolutionary processes and the molecular basis of how sibling species adapt to contrasting environments, and offers valuable resources for future climate-resilient breeding
R32 Compressor for Air conditioning and Refrigeration applications in China
No full textThis paper evaluates the compressor performance and reliability impact by using R32 refrigerant for air conditioning (residential and commercial system); Performance and reliability impacts are compared with different popular refrigerants used in China, for example, R410A & R22 for AC. The design improvement on the scroll compressor will be discussed in order to reach required efficiency and reliability; these improvements include lubrication, internal heat management, motor design, and vapor injection technologies, etc
Decoding soil health constraints in regional agroecosystems: Machine learning reveals microbial enzymatic thresholds and drivers
No full texthttp://dx.doi.org/10.13039/501100001809 National Natural Science Foundation of Chinahttp://dx.doi.org/10.13039/501100018647 RUDN Universityhttp://dx.doi.org/10.13039/501100017549 Science and Technology Innovation 2025 Major Project of Ningbo Municipalit
Nucleation-Mediated Aluminum Deposition/Stripping for Long-Life Molten Salt Aluminum Batteries
No full textMolten salt aluminum batteries (MSABs) hold significant promise for grid-scale energy storage due to the low cost and high capacity of the aluminum anode. However, an aluminum dendrite stemming from nonuniform electrodeposition leads to safety and stability issues. Here, we describe a membrane electrode with predeposited aluminum metal featuring surface-mediated nucleation and growth behavior for operation in alkali chloroaluminate melt electrolytes. The introduction of TiN, as aluminophilic sites, facilitates the initial growth of aluminum on TiN by forming Al-N bonding, thereby enabling uniform aluminum nucleation and mediated growth along the TiN/C fiber, resulting in reversible and dendrite-free aluminum plating/stripping. The TiN/C@Al electrode enables symmetric cells to maintain stable cycling for over 850 h (10.0 mA cm-2; 5.0 mA h cm-2) and shows high rate performance at up to 30.0 mA cm-2. The Al-graphite cell using a TiN/C@Al anode demonstrates long-term stability over 7000 cycles at 2.0 A g-1 and enhanced rate capability with 72.2 mA h g-1 even at 5.0 A g-1. To validate practical scalability, we designed an Ah-level TiN/C@Al-based molten salt Al-graphite pouch cell. This approach offers a scalable pathway for overcoming the limitations of state-of-the-art anodes in MSABs, enabling high-performance and cost-effective energy storage solutions.This work was supported by the National Natural Science Foundation of China (NSFC, 92372115) and the Beijing Natural Science Foundation (NoZ220020). We also acknowledge the support from the National Natural Science Foundation of China (NSFC, grant no. 22075002) and the China Postdoctoral Science Foundation (grant no. 8206300678). We also acknowledge the support from the China National Petroleum Corporation-Peking University Strategic Cooperation Project of Fundamental Research and the Red Avenue Postdoctoral Program in the School of Materials Science and Engineering of Peking University. We also acknowledge the Materials Processing and Analysis Center of Peking University for instrument use
Data for "In-situ strain tuning in hBN-encapsulated graphene electronic devices"
No full text<p>Data for the publication "In-situ strain tuning in hBN-encapsulated graphene electronic devices"</p>
Data for "Mobility enhancement in graphene by in situ reduction of random strain fluctuations"
No full textData for "Mobility enhancement in graphene by in situ reduction of random strain fluctuations"</p
Data for "In-situ strain tuning in hBN-encapsulated graphene electronic devices"
No full text<p>Data for the publication "In-situ strain tuning in hBN-encapsulated graphene electronic devices"</p>
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