299 research outputs found
In-situ electrochemical fabrication of natural contacts on single nanowires
We report a template-based in-situ electrochemical method for fabricating
natural electric contacts on single nanowires using a pair of cross-patterned
electrodes. Such electric contacts are highly stable upon thermal cycling
between room temperature and milli-Kelvin temperatures. Direct imaging of the
single-nanowire contacts using scanning electron microscopy is also
demonstrated.Comment: 13 pages, 4 figure
Application Effect of Limited Fluid Resuscitation in Emergency Patients with Multiple Trauma Complicated with Shock
This article explores the methods and effects of limited fluid resuscitation in the treatment of hemorrhagic shock caused by multiple trauma, which is common in clinic. 80 patients with multiple trauma complicated with shock were randomly selected from the emergency department of our hospital and divided into the observation group and the control group, with 40 members in each group. Patients in the observation group were treated with limited fluid resuscitation, while those in the control group were treated with aggressive fluid resuscitation. By comparing the therapeutic effects of the two groups, it is concluded that the therapeutic effect of the observation group is significantly better than that of the control group. Therefore, adopting limited fluid resuscitation in the clinical treatment of patients with multiple trauma complicated with shock can realize faster recovery, as well as protect patients’ coagulation function, effectively reducing complications and mortality. Moreover, it can also reduce the injury of trauma perfusion to the body, ensuring the recovery of patients
Suboptimal subspace construction for log-determinant approximation
Variance reduction is a crucial idea for Monte Carlo simulation and the
stochastic Lanczos quadrature method is a dedicated method to approximate the
trace of a matrix function. Inspired by their advantages, we combine these two
techniques to approximate the log-determinant of large-scale symmetric positive
definite matrices. Key questions to be answered for such a method are how to
construct or choose an appropriate projection subspace and derive guaranteed
theoretical analysis. This paper applies some probabilistic approaches
including the projection-cost-preserving sketch and matrix concentration
inequalities to construct a suboptimal subspace. Furthermore, we provide some
insights on choosing design parameters in the underlying algorithm by deriving
corresponding approximation error and probabilistic error estimations.
Numerical experiments demonstrate our method's effectiveness and illustrate the
quality of the derived error bounds
Will Lanczos Iterations Generate Symmetric Quadrature Nodes?
The Golub-Welsch algorithm [Math. Comp., 23: 221-230 (1969)] for computing
Gaussian quadrature rules is of importance in estimating quadratic forms.
Quadrature rules based on this algorithm have long been assumed to be
symmetric. Recent research indicates that the presence of asymmetric quadrature
nodes may be more often. Such a divergence has led to varying error analyses of
the Lanczos quadrature method. Since symmetry often implies simplicity, it is
of great interest to ask when do Lanczos iterations generate symmetric
quadrature rules. This paper derives a sufficient condition that ensures
symmetric quadrature nodes which partially answers the question that when the
Ritz values of a symmetric matrix are symmetrically distributed. Additionally,
we establish both lower and upper bounds on the disparity between the minimum
Lanczos iterations required for symmetric and asymmetric quadrature.Comment: 17 pages, 2 figure
An analysis on stochastic Lanczos quadrature with asymmetric quadrature nodes
The stochastic Lanczos quadrature method has garnered significant attention
recently. Upon examination of the error analyses given by Ubaru, Chen and Saad
and Cortinovis and Kressner, certain notable inconsistencies arise. It turns
out that the former's results are valid for cases with symmetric quadrature
nodes and may not be adequate for many practical cases such as estimating log
determinant of matrices. This paper analyzes probabilistic error bound of the
stochastic Lanczos quadrature method for cases with asymmetric quadrature
nodes. Besides, an optimized error allocation technique is employed to minimize
the overall number of matrix vector multiplications required by the stochastic
Lanczos quadrature method.Comment: 20 pages, 3 figure
Investigation of adhesive joining strategies for the application of a multi-material light rail vehicle
© 2021 The Author(s). Licensee MDPI, Basel, Switzerland. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/To meet the high demand for lightweight energy-efficient and safe structures for transport applications, a current state-of-the-art light rail vehicle structure is under development that adopts a multi-material design strategy. This strategy creates the need for advanced multi-material joining technologies. The compatibility of the adhesive with a wide range of material types and the possibility of joining multi-material structures is also a key advantage to its success. In this paper, the feasibility of using either epoxy or polyurethane adhesive joining techniques applied to the multi-material vehicle structure is investigated. Importantly, consideration is given to the effect of variation in bond thickness for both families of structural adhesives. Multi-material adhesively bonded single lap joints with different adhesives of controlled bond thicknesses were manufactured and tested in order to experimentally assess the shear strength and stiffness. The torsional stiffness and natural frequency of the vehicle were modelled using a global two-dimensional finite element model (FEM) with different adhesive properties, and the obtained vehicle performances were further explained by the coupon-level experimental tests. The results showed that the vehicle using polyurethane adhesive with a target bond thickness of 1.0 mm allowed for optimal modal frequency and weight reduction.Peer reviewe
Efficient Cross-Lingual Transfer for Chinese Stable Diffusion with Images as Pivots
Diffusion models have made impressive progress in text-to-image synthesis.
However, training such large-scale models (e.g. Stable Diffusion), from scratch
requires high computational costs and massive high-quality text-image pairs,
which becomes unaffordable in other languages. To handle this challenge, we
propose IAP, a simple but effective method to transfer English Stable Diffusion
into Chinese. IAP optimizes only a separate Chinese text encoder with all other
parameters fixed to align Chinese semantics space to the English one in CLIP.
To achieve this, we innovatively treat images as pivots and minimize the
distance of attentive features produced from cross-attention between images and
each language respectively. In this way, IAP establishes connections of
Chinese, English and visual semantics in CLIP's embedding space efficiently,
advancing the quality of the generated image with direct Chinese prompts.
Experimental results show that our method outperforms several strong Chinese
diffusion models with only 5%~10% training data
Karst collapse risk zonation and evaluation in Wuhan, China based on analytic hierarchy process, logistic regression, and insar angular distortion approaches
The current study presents a detailed assessment of risk zones related to karst collapse in Wuhan by analytical hierarchy process (AHP) and logistic regression (LR) models. The results showed that the LR model was more accurate with an area under the receiver operating characteristic (ROC) curve of 0.911 compared to 0.812 derived from the AHP model. Both models performed well in identifying high-risk zones with only a 3% discrepancy in area. However, for the medium-and low-risk classes, although the spatial distribution of risk zoning results were similar between two approaches, the spatial extent of the risk areas varied between final models. The reliability of both methods were reduced significantly by excluding the InSAR-based ground subsidence map from the analysis, with the karst collapse presence falling into the high-risk zone being reduced by approximately 14%, and karst collapse absence falling into the karst area being increased by approximately 6.5% on the training samples. To evaluate the practicality of using only results from ground subsidence maps for the risk zonation, the results of AHP and LR are compared with a weighted angular distortion (WAD) method for karst risk zoning in Wuhan. We find that the areas with relatively large subsidence horizontal gradient values within the karst belts are generally spatially consistent with high-risk class areas identified by the AHP-and LR-based approaches. However, the WAD-based approach cannot be used alone as an ideal karst collapse risk assessment model as it does not include geological and natural factors into the risk zonation. © 2021 by the authors. Licensee MDPI, Basel, Switzerland
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