460 research outputs found
sj-docx-1-imj-10.1177_10815589231169686 – Supplemental material for Development and validation of a simple-to-use nomogram for predicting the delayed radiographic recovery in children with mycoplasma pneumoniae pneumonia complicated with atelectasis
No full textSupplemental material, sj-docx-1-imj-10.1177_10815589231169686 for Development and validation of a simple-to-use nomogram for predicting the delayed radiographic recovery in children with mycoplasma pneumoniae pneumonia complicated with atelectasis by Yonghan Luo, Jihong Dai, Guojing Tang, Shan He and Wenlong Fu in Journal of Investigative Medicine</p
Substantially strengthening a dual-phase titanium alloy by moderate oxygen doping
No full textAs one of the detrimental ingredients, oxygen can, even in a small amount, substantially reduce the ductility of Ti alloys. Here, rather than being discouraged by the negative effects of oxygen on ductility, an equiaxed dual-phase Ti-8Nb-2Fe-0.66O (wt.%) alloy showing ultrahigh yield strength (1386 MPa) and good tensile ductility (fracture elongation similar to 10.8%) was developed. The oxygen-containing alloy is 87% stronger than the oxygen-free base alloy whereas the ductility loss is marginal. The effects of oxygen interstitials can be twofold: they led to significant solid-solution strengthening by pinning dislocations and suppressing stress-induced martensitic transformation; the equiaxed alpha + beta dual-phase with basal alpha texture doped by oxygen promoted multiple -type and -type dislocation activities that guaranteed good ductility. This work demonstrates a new avenue to develop high-strength Ti alloys by doping oxygen interstitials, which takes full advantage of the beneficial strengthening factor of oxygen while avoiding its detrimental embrittlement effect
Achieving large near-linear elasticity, low modulus, and high strength in a metastable β-Tialloy by mild cold rolling
No full textSimultaneously achieving high elasticity, low modulus, and high strength in Ti alloy has been a longstanding challenge. In this study, cold rolling was conducted to modulate the martensitic transformation of the Ti-15Nb-5Zr-4Sn-1Fe alloy to address this challenge. The 10% cold rolling process was primarily accommodated by a novel stress-induced sequential beta-to- alpha '' -to- alpha ' martensitic transformation accompanied by the disappearance of omega phase, which was sufficient to induce adequate martensite and defects to suppress the initial rapid stress-induced martensitic transformation, without destroying the equiaxed shape of prior beta grains. Consequently, the novel sequential phase transformation led to a substantial decrease in Young's modulus by 50.5% while increasing the strength, resulting in an excellent combination of large near-linear elasticity of 2.34%, low modulus of 45 GPa, and high strength of 1093 MPa. The obtained large near-linear elasticity was mainly contributed by the concurrent low modulus and high strength obeying Hooke's law. These findings provide valuable insights into the attainment of concurrent high elasticity and low modulus in Ti alloys by regulating the stress-induced sequential martensitic transformation. (c) 2024 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology
Plasmonic nanoparticle superlattice nanosheets: design, fabrication & applications
No full textOrdered periodic arrays of metal nanoparticles, termed superlattices, are attracting increasing interest in the modern field of nanoscience and nanotechnology due to the ability to enable engineering of unprecedented light-matter interactions. This offers a highly promising pathway towards discovery of novel optical phenomena that plays a pivotal role in shaping up future next-generation technological devices. However, the precise assembly of nanoparticles into well-defined superlattices with tunable plasmonics still remains a grand technical challenge with existing approaches. The downstream integration of such superlattices into real world technologies is also another issue which is currently hampered by the limited lateral dimension and rigidity of most superlattice assemblies. To address these existing challenges, this thesis introduces Plasmene, which is a conceptually new class of two-dimensional materials assembled from meta-atoms from the “plasmonic periodic table”. A general and robust bottom-up soft ligand-based approach in conjunction with evaporation mediated self-assembly at air-water interface was successfully designed to fabricate the plasmene nanosheets. These sheets are free-standing and monolayered in nature, with ultimate nanoscale thickness but macroscopic lateral dimensions. In addition, plasmene nanosheets possesses several unique features. For instance: 1) Its mechanical robustness allows demonstration of the first patterning and folding of 2D plasmene into 1D nanoribbons and 3D origami nanostructures, 2) Support of surface propagating plasmonics enabled their use as a superlattice-fiber waveguide coupler with polarizer selectivity, and 3) Localized gap plasmonics, high mechanical flexibility and optical transparency features enabled their use as a soft surface-enhanced Raman scattering (SERS) substrate for direct chemical detection. The successful design of plasmene nanosheets with simultaneous structural and functional control allows fundamental understanding of the self-assembly and plasmonic coupling interactions of nanoparticles, which will facilitate integration into the downstream real-world forensic applications. This was demonstrated in two separate studies. First, plasmene nanosheets allowed both qualitative and quantitative analysis of illicit and pharmaceutical drug overdose, as well as detection of trace amount of drugs on banknotes. Secondly, plasmene sheets can serve as dual-coded anti-counterfeit security label for banknotes. By engineering the geometrical parameters of the plasmene building blocks and choice of SERS molecular label, it allows virtually unlimited coding capabilities which opens a new route towards future anti-counterfeit technologies
Phlugiolopsis yunnanensis Shi & Ou 2005
No full text5. Phlugiolopsis yunnanensis Shi & Ou, 2005 (Map. 1, Figs. 5, 12: I–J) Phlugiolopsis yunnanensis Shi & Ou, 2005: 359 –361. Type specimen: male; type locality: Jingping, Jingdong, Yunnan, China; location of type specimen: Museum of Hebei University. Rediscription. Basal area of female subgenital plate faintly broad, apical half slightly narrow, basal margin slightly excavate, baso-lateral margin expanded, tongue-shaped, curved dorsad; lateral margin strongly concave; posterior margin obtusely rounded. Material examined. Holotype: male, Jingping, Jingdong, Yunnan, 17 November 2003, collected by Xiao- Hong Ou. Paratypes: 1 male and 2 females, Wenlong, Jingdong, Yunnan, 10 November 2003, collected by Xiao- Hong Ou. Other specimens (conserved in alcohol): 1 male, Puʹer, Yunnan, 28 July 2007, collected by Fu-Ming Shi; 1 male, Puʹer, Yunnan, 26 August 2009, collected by Ming Qiu and Rui-Lian Li; 1 female, Taizhong, Jingdong, Yunnan, 18 August 2009, Ming Qiu and Rui-Lian Li; 1 male and 3 females, Dajie, Jingdong, Yunnan, 21 August 2009, collected by Ming Qiu and Rui-Lian Li. Distribution. China (Yunnan).Published as part of Bian, Xun, Shi, Fu-Ming & Chang, Yan-Lin, 2012, Review of the genus Phlugiolopsis Zeuner, 1940 (Orthoptera: Tettigoniidae: Meconematinae) from China, pp. 1-21 in Zootaxa 3281 on page 8, DOI: 10.5281/zenodo.20992
Feature Extraction in Edge Detection using Genetic Programming
No full textEdge detection is important in image processing. Extracting edge features is the main and necessary process in edge detection. Since features in edge detection are implicit, most of the existing edge features only work well on specific images. Using a moving window has a trade-off between noise rejection and localisation accuracy. Genetic Programming (GP) has been widely applied to image processing, and GP has potential for extracting edge features, although there is little work in GP for edge detection. The overall goal of this thesis is to investigate GP for automatic edge feature extraction using different amounts of existing knowledge from only using raw pixel intensities and ground truth to more advanced domain knowledge such as Gaussian filters.
First of all, this thesis conducts an investigation on fundamental low-level edge detector construction with very little prior edge knowledge. Search operators based on a single raw pixel, a block of pixels, and two blocks of pixels are proposed to construct edge detectors. Unlike most existing methods, this GP system automatically searches neighbours and avoids manually predefining a window size. The results show that the evolved edge detectors outperform some existing edge detectors, such as the Sobel edge detector.
Secondly, from the pixel and image views, localisation of detected edges, and observations of GP programs, new fitness functions are suggested in this thesis. It is found that the pixel view is better than the image view to design fitness functions without allowing a distance from predictions to ground truth. However, in terms of edge localisation, the pixel view is worse than the image view to design fitness functions. A new fitness function combining detection accuracy and localisation effectively improves the performance of evolved edge detectors. When utilising observations of GP programs to construct soft edge maps, two new fitness functions including a restriction on the range of observations are proposed to evolve edge detectors with good soft edge maps on test images.
Thirdly, pixels implicitly selected by the GP system based on full images are analysed. A set of pixels are extracted from the evolved programs and used to construct edge filters. A merge operation is proposed to extract six pixels to construct second-order edge filters. The results show that a rich but compact set of pixels can be extracted from the evolved edge detectors.
Fourthly, GP is utilised to evolve edge detectors based on the Gaussian-based technique. These GP evolved edge detectors are significantly better than the Gaussian gradient and the surround suppression technique. An efficient and effective sampling technique is proposed for evolving Gaussian-based edge detectors. From the results, there are no significant differences between the Gaussian-based edge detectors evolved by a full set of images and by the sampling technique on the training set.
Fifthly, GP is employed to construct features using an existing set of basic features. The distribution of observations of GP programs is estimated. Evolved composite features are proposed using known distribution models to indicate the probability of pixels being discriminated as edge points. It is found that the composite features effectively combine advantages of basic features and can richly indicate edge responses.
Finally, a Bayesian-based GP system is proposed to construct high-level edge features via employing two general algebraic operators and a function developed from a simple Bayesian model. The simple Bayesian model utilises a general multivariate normal density to combine basic features. Experiments show that the GP evolved programs perform better than the simple Bayesian model to obtain composite features.
Overall, this thesis shows that GP has the capability to effectively extract edge features using different degrees of prior knowledge about edges
Ji yu yun dong neng li you shi de shai xuan: xi jun ji qun yun dong de ji ti nai yao xing ji zhi
No full textPh.D.Bacterial cell motility is essential for avoiding predators, searching for food (chemotaxis), propagation and colonization. Swarming, as a common collective motion form of flagellated bacteria, enables bacteria to colonize moist surface effectively. Particularly, bacterial swarming exhibits the ability to navigate against antibiotic stress known as collective antibiotic tolerance. Bacteria are known to survive from antibiotic stress with multiple mechanisms individually or collectively, however it is unclear how cell motility plays a role in collective antibiotic tolerance during bacterial swarming.In this thesis, we demonstrate the collective antibiotic tolerance of bacterial swarming as a consequence of selection for motility but not growth advantage. We find a spatial heteroresistance distribution along swarm direction under antibiotic stress which is correlated with cell motility advantage. With single-cell tracking in dense swarm colony, we find that cells display a biased motion pattern with longer persistence time when swimming towards the leading edge. Furthermore, we find the bias towards the leading edge is proportional to the swimming speed of individual cell. The speed-dependent persistence time bias enables the enrichment of cells with higher speed at swarming edge. This is consistent with the selection for cell motility during swarming expansion. We also show that the biased motion pattern may depend on cell-cell interaction and symmetry breaking at the leading edge, and is consistent under antibiotic stress. At last, we show that with suppressive antibiotic pairs, motility of sensitive strain could be restored and therefore the enrichment of antibiotic-resistant strain is inhibited.Fitness represents the ability of a population to adapt to the environment. Growth advantage is always the first consideration when people refer to fitness under environmental stress. Here we suggest that motility fitness may dominate the selection advantage during swarming. Selection for motility fitness supports the faster sub-population (the tolerant or resistant sub-population under environmental stress) to enrich at swarming edge and maintain the expansion of the whole colony. Therefore, we propose that motility fitness is another evolutionary advantage other than growth fitness.細菌尋找食物（趨化性，chemotaxis）、躲避捕食者、遷徙以及擴張佔領更廣闊的區域都離不開運動力。集群運動（swarming）是依賴鞭毛運動的細菌的一種普遍集體運動方式，可以幫助細菌更有效的佔領濕潤的表面。特別的，細菌的集群運動具有集體耐藥性（collective antibiotic tolerance）使其有能力在抗生素的壓力下繼續擴張。前人的研究中已經發現了許多機制幫助細菌個體或集體在抗生素的壓力中生存。但是，細菌的運動能力在集體抗藥性中的作用仍然不是很清楚。在本文中，我們展示了對運動能力優勢而不是生長優勢的選擇導致了細菌集群運動的集體耐藥性。我們發現當集群運動通過有抗生素壓力的區域時，在集群運動的擴張方向上細菌的耐藥性（或抗藥性）在空間上的分佈是不均一的（heteroresistance），這種耐藥性的不均一性與細菌的運動能力有關。通過對進群運動中的單細菌運動進行追蹤，我們發現細菌展現出一種有偏差（bias）的運動模式，即在朝向擴張邊界的方向運動時可以持續更長的時間（persistence time）。更進一步的，我們發現這種朝向擴張邊界的偏差正比于細菌個體的運動速度。這種速度依賴的持續時間的偏差使得運動速度更快的細菌可以富集在擴張的邊界上，這和我們看到的集群運動擴張中對運動能力的選擇是一致的。這種有偏差的運動模式很可能與細菌之間的相互作用以及在擴張邊界上的不對稱性有關，也不受環境中抗生素壓力的影響。最後，我們發現相互抑制的抗生素組合可以幫助沒有耐藥性的細菌恢復運動能力，從而抑制對有抗藥性細菌的富集作用。適應度（fitness）是一個群體對環境適應性的量度。對於細菌來說，我們往往使用生長優勢來代替它在環境壓力下的適應程度。在本文中我們提出，在集群運動的擴張中，對運動能力的優勢的選擇佔有主導的地位。這種對運動能力的選擇可以在環境壓力下讓運動更快的子群體（即有耐藥性或者抗藥性的子群體）富集在擴張邊界并維持整個菌落的擴張。綜上所述，我們展示了一種不同于對生長優勢選擇而是對運動能力選擇的進化形式。Zuo, Wenlong = 基於運動能力優勢的篩選 : 細菌集群運動的集體耐藥性機制 / 左文龍.Thesis Ph.D. Chinese University of Hong Kong 2019.Includes bibliographical references (leaves 103-112).Abstracts also in Chinese.Title from PDF title page (viewed on 20 May, 2021).Zuo, Wenlong = Ji yu yun dong neng li you shi de shai xuan : xi jun ji qun yun dong de ji ti nai yao xing ji zhi / Zuo Wenlong
Multiobjective Optimal Control of FOPID Controller for Hydraulic Turbine Governing Systems Based on Reinforced Multiobjective Harris Hawks Optimization Coupling with Hybrid Strategies
No full textThe controlling parameter tuning of the hydraulic turbine governing system (HTGS) is always deduced under single operating condition and is not suitable for the changeable operating conditions of the hydraulic turbine. For this purpose, multiobjective optimization problem of fractional order PID (FOPID) controller for HTGS is constructed through the consideration of no-load disturbance and on-load disturbance operation conditions, where the performance indicators of integral time absolute error (ITAE) under both operation conditions are employed as the objective functions. To achieve the optimum, the multiobjective version of newly proposed Harris hawks optimization (MOHHO) is established to solve the optimization issue. Additionally, hybrid strategies which include Latin hypercube sampling initialization, modified differential evolution operator, and mutation operator are coupled into MOHHO (HMOHHO) to promote the global searching capability. Simultaneously, the linear model of rabbit energy within MOHHO is replaced with a nonlinear one to further enhance the searching capacity. Subsequently, the effectiveness and superiority of the proposed HMOHHO are verified by several multiobjective UF and ZDT test problems. Finally, the practical application and contrastive analysis ascertain that the constructed multiobjective problem of FOPID controller is suitable for HTGS under changeable operating conditions, and the proposed HMOHHO is effective in solving the issue
A new branch and bound algorithm for noncovex quadratic programming with box constraints
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