Rationalization of trusses and yield-line patterns identified using layout optimization

To help engineers to design and analyse structures, various tools exist. However, many of them are complicated and difficult for engineers to master. In industry simple, accurate, and rapid tools are potentially very useful. The development of such tools has thus been the main focus of this thesis. One application is the design of lightweight truss structures. Although techniques have been available to identify efficient truss designs for more than half a century, these are not widely used in industry. A major problem is that the structures generated are often complex in form, so that manufacturing becomes problematic. To address this, the current research explores two rationalization techniques: (i) introducing joint lengths to control the number of joints that exist in the resulting structure; and (ii) utilising geometry optimization to adjust the locations of joints in a truss. The former involves a minor modification to the standard process such that it retains the linear nature of the original problem, while the latter solves a more challenging non-linear optimization problem that can simultaneously simplify (make less complicated) and improve (make lighter) a given truss layout. To ensure a rapid and reliable process for the latter, analytical expressions of functions and their derivatives are supplied to a general purpose non-linear optimizer and various practical issues are also considered. A number of benchmark problems are solved to show the efficacy of the two rationalization techniques. Another application is yield-line analysis of reinforced concrete slabs. Even in the modern computer age, with many engineering analysis procedures successfully computerized, a fully automated means of undertaking a yield-line analysis has been lacking, forcing engineers in industry to use hand-calculations in order to benefit from the power of the yield-line method. This thesis is therefore concerned with the development of techniques that automate this method. By utilising the novel discontinuity layout optimization (DLO) method, the process of yield-line analysis has been truly automated at last. In addition, motivated by the outcomes of the rationalization procedure developed for trusses, research has been conducted to rationalize yield-line patterns generated via DLO. Similar to the technique used in trusses, analytical expressions of functions and their derivatives are deduced and then supplied to a non-linear optimizer, leading to a rapid and reliable computational process. To make DLO and the rationalization ready for use in industry, various slab configurations found in practice are also considered, permitting challenging slab problems to be tackled using the method. A number of examples from the literature and industry are analysed to demonstrate the efficacy of DLO and the rationalization technique

An adaptation model for trabecular bone at different mechanical levels

<p>Abstract</p> <p>Background</p> <p>Bone has the ability to adapt to mechanical usage or other biophysical stimuli in terms of its mass and architecture, indicating that a certain mechanism exists for monitoring mechanical usage and controlling the bone's adaptation behaviors. There are four zones describing different bone adaptation behaviors: the disuse, adaptation, overload, and pathologic overload zones. In different zones, the changes of bone mass, as calculated by the difference between the amount of bone formed and what is resorbed, should be different.</p> <p>Methods</p> <p>An adaptation model for the trabecular bone at different mechanical levels was presented in this study based on a number of experimental observations and numerical algorithms in the literature. In the proposed model, the amount of bone formation and the probability of bone remodeling activation were proposed in accordance with the mechanical levels. Seven numerical simulation cases under different mechanical conditions were analyzed as examples by incorporating the adaptation model presented in this paper with the finite element method.</p> <p>Results</p> <p>The proposed bone adaptation model describes the well-known bone adaptation behaviors in different zones. The bone mass and architecture of the bone tissue within the adaptation zone almost remained unchanged. Although the probability of osteoclastic activation is enhanced in the overload zone, the potential of osteoblasts to form bones compensate for the osteoclastic resorption, eventually strengthening the bones. In the disuse zone, the disuse-mode remodeling removes bone tissue in disuse zone.</p> <p>Conclusions</p> <p>The study seeks to provide better understanding of the relationships between bone morphology and the mechanical, as well as biological environments. Furthermore, this paper provides a computational model and methodology for the numerical simulation of changes of bone structural morphology that are caused by changes of mechanical and biological environments.</p

Physicochemical properties of superfine grinding-microwave modified artichoke soluble dietary fiber and their alleviation of alcoholic fatty liver in mice

The effects of superfine grinding (SG) and microwave treatment (MT) on the structure and physicochemical properties of artichoke soluble dietary fiber (ASDF) and its protective effects on mice with alcoholic fatty liver (AFL) were studied. We compared the changes in structural characteristics and physicochemical properties of ASDF, SG-ASDF (ASDF treated by SG), MT-ASDF (ASDF treated by MT), and CM-ASDF (ASDF treated by SG and MT). Moreover, we evaluated the effects of the obtained ASDF on the growth characteristics, blood lipid levels, and liver of mice with AFL. Our results of the study showed that CM-ASDF had a more concentrated and uniform particle size, a higher extraction rate of ASDF and significantly improved water-holding capacity (WHC), oil-holding capacity (OHC) and water swelling capacity (WSC) of ASDF (p &lt; 0.05). After the ASDF intervention, mice with AFL exhibited a significant improvement in body lipid levels and reduce liver inflammation. Specifically, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malonaldehyde (MDA), Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were significantly increased (p &lt; 0.05). And the hematoxylin–eosin (HE) staining results showed significant improvement of hepatic steatosis in mice with AFL. In summary, our study found that both SG and MT could improve the structure and physicochemical properties of ASDF, with CM-ASDF being the most effective. Additionally, CM-ASDF was selected to continue the investigation and demonstrated an excellent protective effect on mice with AFL, with the high dose group (H-ASDF) showing the greatest benefit. These findings provided some new insights for future comprehensive utilization of ASDF and drug development for the treatment of AFL

Laser-induced periodic annular surface structures on fused silica surface

International audienceWe report on the formation of laser-induced periodic annular surface structures on fused silica irradiated with multiple femtosecond laser pulses. This surface morphology emerges after the disappearance of the conventional laser induced periodic surface structures, under successive laser pulse irradiation. It is independent of the laser polarization and universally observed for different focusing geometries. We interpret its formation in terms of the interference between the reflected laser field on the surface of the damage crater and the incident laser pulse

Microbial functional trait of rRNA operon copy numbers increases with organic levels in anaerobic digesters.

The ecological concept of the r-K life history strategy is widely applied in macro-ecology to characterize functional traits of taxa. However, its adoption in microbial communities is limited, owing to the lack of a measureable, convenient functional trait for classification. In this study, we performed an experiment of stepwise organic amendments in triplicate anaerobic digesters. We found that high resource availability significantly favored microbial r-strategists such as Bacillus spp. Incremental resource availability heightened average rRNA operon copy number of microbial community, resulting in a strong, positive correlation (r&gt;0.74, P&lt;0.008). This study quantifies how resource availability manipulations influence microbial community composition and supports the idea that rRNA operon copy number is an ecologically meaningful trait which reflects resource availability

Identification of ferroptosis-related genes in the progress of NASH

BackgroundNon-alcoholic steatohepatitis (NASH) is becoming more widespread, and some similarities exist between its etiology and ferroptosis. However, there are limited investigations on which ferroptosis-related genes (FRGs) are regulated in NASH and how to regulate them. We screened and validated the pivotal genes linked to ferroptosis in NASH to comprehend the function of ferroptosis in the development of NASH.MethodsTwo mRNA expression data were obtained from the Gene Expression Omnibus (GEO) as the training set and validation set respectively. FRGs were downloaded from FerrDb. The candidate genes were obtained from the intersection between differentially expressed genes (DEGs) and FRGs, and further analyzed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The hub genes were identified by the protein-protein interaction (PPI) network and Cytoscape. Then, FRGs closely related to the severity of NASH were identified and further confirmed using the validation set and mouse models. Ultimately, based on these genes, a diagnostic model was established to differentiate NASH from normal tissues using another data set from GEO.ResultsA total of 327 FRGs in NASH were acquired and subjected to GSEA. And 42 candidate genes were attained by overlapping the 585 FRGs with 2823 DEGs, and enrichment analysis revealed that these genes were primarily engaged in the fatty acid metabolic, inflammatory response, and oxidative stress. A total of 10 hub genes (PTGS2、IL1B、IL6、NQO1、ZFP36、SIRT1、ATF3、CDKN1A、EGR1、NOX4) were then screened by PPI network. The association between the expression of 10 hub genes and the progress of NASH was subsequently evaluated by a training set and verified by a validation set and mouse models. CDKN1A was up-regulated along with the development of NASH while SIRT1 was negatively correlated with the course of the disease. And the diagnostic model based on CDKN1A and SIRT1 successfully distinguished NASH from normal samples.ConclusionIn summary, our findings provide a new approach for the diagnosis, prognosis, and treatment of NASH based on FRGs, while advancing our understanding of ferroptosis in NASH

Limit analysis of non-periodic masonry by means of Discontinuity Layout Optimization

Masonry structures forming part of our historical heritage were often constructed using nonperiodic textures. In this case, unlike the situation for masonry with periodic textures, few methods are available to estimate wall strength and, moreover, available methods are often difficult to apply. In this work, Discontinuity Layout Optimization (DLO) is proposed as a method of estimating the failure load and associated mechanism of masonry walls constructed with non-periodic textures. In the first part three different textures are considered (periodic, quasi-periodic and chaotic) with a simplified scheme and a parametric analysis is undertaken, considering the variation of the height of the panel. A further classification for quasi-periodic textures is then provided and a DLO rigid block analysis is carried for square panels to show the influence of such textures. The results highlight the importance of the parameters considered in the analysis, and that DLO is a suitable method to investigate their influence