| 1. |
- Jin, Ying-Hui, et al.
(författare)
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Chemoprophylaxis, diagnosis, treatments, and discharge management of COVID-19 : An evidence-based clinical practice guideline (updated version)
- 2020
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Ingår i: Military Medical Research. - : Springer Science and Business Media LLC. - 2054-9369. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of a rapidly spreading illness, coronavirus disease 2019 (COVID-19), affecting more than seventeen million people around the world. Diagnosis and treatment guidelines for clinicians caring for patients are needed. In the early stage, we have issued "A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version)"; now there are many direct evidences emerged and may change some of previous recommendations and it is ripe for develop an evidence-based guideline. We formed a working group of clinical experts and methodologists. The steering group members proposed 29 questions that are relevant to the management of COVID-19 covering the following areas: chemoprophylaxis, diagnosis, treatments, and discharge management. We searched the literature for direct evidence on the management of COVID-19, and assessed its certainty generated recommendations using the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach. Recommendations were either strong or weak, or in the form of ungraded consensus-based statement. Finally, we issued 34 statements. Among them, 6 were strong recommendations for, 14 were weak recommendations for, 3 were weak recommendations against and 11 were ungraded consensus-based statement. They covered topics of chemoprophylaxis (including agents and Traditional Chinese Medicine (TCM) agents), diagnosis (including clinical manifestations, reverse transcription-polymerase chain reaction (RT-PCR), respiratory tract specimens, IgM and IgG antibody tests, chest computed tomography, chest x-ray, and CT features of asymptomatic infections), treatments (including lopinavir-ritonavir, umifenovir, favipiravir, interferon, remdesivir, combination of antiviral drugs, hydroxychloroquine/chloroquine, interleukin-6 inhibitors, interleukin-1 inhibitors, glucocorticoid, qingfei paidu decoction, lianhua qingwen granules/capsules, convalescent plasma, lung transplantation, invasive or noninvasive ventilation, and extracorporeal membrane oxygenation (ECMO)), and discharge management (including discharge criteria and management plan in patients whose RT-PCR retesting shows SARS-CoV-2 positive after discharge). We also created two figures of these recommendations for the implementation purpose. We hope these recommendations can help support healthcare workers caring for COVID-19 patients.
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| 2. |
- Reimers, Jeffrey R., et al.
(författare)
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Challenges facing an understanding of the nature of low-energy excited states in photosynthesis
- 2016
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Ingår i: Biochimica et Biophysica Acta - Bioenergetics. - : Elsevier BV. - 0005-2728 .- 1879-2650. ; 1857:9, s. 1627-1640
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Forskningsöversikt (refereegranskat)abstract
- While the majority of the photochemical states and pathways related to the biological capture of solar energy are now well understood and provide paradigms for artificial device design, additional low-energy states have been discovered in many systems with obscure origins and significance. However, as low-energy states are naively expected to be critical to function, these observations pose important challenges. A review of known properties of low energy states covering eight photochemical systems, and options for their interpretation, are presented. A concerted experimental and theoretical research strategy is suggested and outlined, this being aimed at providing a fully comprehensive understanding.
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| 3. |
- Liu, Yang, et al.
(författare)
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Evolution of residual stress when turning a fillet radius in stainless steel
- 2023
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Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 85, s. 216-226
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Tidskriftsartikel (refereegranskat)abstract
- Most studies have been carried out to investigate the surface integrity induced by metal cutting process. However, the previous studies are limited to a longitudinal turning or orthogonal cutting operations and the residual stresses generated in a fillet radius have been ignored. This study uses a combination of experiments and numerical simulations to study the evolution of cutting forces, temperature, chip morphology, and residual stress distributions while turning a fillet radius in AISI 304. Finite Element (FE) models were developed with a Coupled Eulerian and Lagrangian (CEL) method, where the geometric model of the workpiece was established taking into account the previous machined surface profile at the four specific cutting faces. The model was validated by experimental cutting forces, chip morphology, and residual stress profiles. The changing trend of shape and area of uncut chip cross-section during fillet turning were analyzed to explain the evolution of cutting forces and temperatures. The results show that the cutting force components in cutting speed and tangential directions increase during the early stage of the fillet turning process and decrease after that, while the force in the radial direction shows an increasing trend during this process. The maximum temperature at the machined surface is increased along the tool path. In addition, magnitude and depth of residual stress are slightly changed during the fillet radius turning process, but a reduction of the residual stress profile can still be noticed.
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| 4. |
- Sullivan, Patrick F., et al.
(författare)
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Leveraging base-pair mammalian constraint to understand genetic variation and human disease
- 2023
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6643, s. 367-
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Tidskriftsartikel (refereegranskat)abstract
- Thousands of genomic regions have been associated with heritable human diseases, but attempts to elucidate biological mechanisms are impeded by an inability to discern which genomic positions are functionally important. Evolutionary constraint is a powerful predictor of function, agnostic to cell type or disease mechanism. Single-base phyloP scores from 240 mammals identified 3.3% of the human genome as significantly constrained and likely functional. We compared phyloP scores to genome annotation, association studies, copy-number variation, clinical genetics findings, and cancer data. Constrained positions are enriched for variants that explain common disease heritability more than other functional annotations. Our results improve variant annotation but also highlight that the regulatory landscape of the human genome still needs to be further explored and linked to disease.
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| 5. |
- Weng, Jian, et al.
(författare)
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A comprehensive study on cutting mechanisms and surface integrity of AISI 304 when turning a curved surface
- 2021
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Ingår i: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 36:11, s. 1285-1298
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Tidskriftsartikel (refereegranskat)abstract
- Most of the studies on cutting mechanisms and surface integrity in turning are investigated with a straight tool path (longitudinal/end face turning) while few contributions have been done in curved surface turning. This work explores the evolutions of cutting force, chip morphology and surface integrity when turning a curved surface, using fillet surface machining of AISI 304 stainless steel. The varying cutting conditions caused by the presented turning are revealed by detailed geometric analysis and employed as indicators for further discussions on cutting force, chip morphology, and machined surface integrity (including surface roughness, microhardness, microstructure, and residual stress). Apart from the difference of cutting force components in tangential, radial, and cutting speed directions along the fillet surface, wider and thinner chips are obtained from end face turning. The measured microhardness, microstructural alternation, and stress condition results comprehensively illustrate a reduction of severe plastic deformation from the outer face to the end face.
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| 6. |
- Weng, Jian, et al.
(författare)
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A hybrid model for force prediction in orthogonal cutting with chamfered tools considering size and edge effect
- 2020
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Ingår i: International Journal of Advanced Manufacturing Technology. - : Springer Science and Business Media LLC. - 0268-3768 .- 1433-3015. ; 110:5-6, s. 1367-1384
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Tidskriftsartikel (refereegranskat)abstract
- Researches on the modeling of machining difficult-to-cut metals are important for optimization of the processing parameters, in which the force modeling is essential due to its significant influence on the performance of tools and the quality of parts. A semi-analytical method for force prediction in orthogonal cutting with chamfered tools considering both edge and size effect is proposed in this paper. The plastic deformation in the shear band was investigated using a parallel shear zone model and unequal division shear zone model. The influence of size effect on cutting force was discussed and a simplified expression of improvement factor is introduced to describe the sharp increase of shear stress under the condition of low feed rate. Simulations of orthogonal cutting with different chamfer lengths are conducted to analyze the variation of cutting force with respect to chamfer length, which reveals that the influence of chamfer length on cutting force is determined by the ratio of chamfer length to uncut chip thickness. A modified function considering the trend of material flow condition is proposed, which treats the total cutting force as a combination of cutting forces caused by chamfered edge and rake face. The calibration of constants in the proposed method is achieved using particle swarm optimization (PSO), a meta-heuristic algorithm for complicated non-linear models. The experiments show that the method works well on both fitting and predicting modules in orthogonal cutting of AISI 304 using cemented carbide tools with 15° chamfer angle or 25° chamfer angle.
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| 7. |
- Weng, Jian, et al.
(författare)
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A machine learning based approach for determining the stress-strain relation of grey cast iron from nanoindentation
- 2020
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Ingår i: Mechanics of Materials. - : Elsevier BV. - 0167-6636. ; 148
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Tidskriftsartikel (refereegranskat)abstract
- Apart from microhardness and elastic modulus, the stress-strain relation is another important characteristic that more and more scholars have been trying to extract from nanoindentation. With the development of artificial intelligence and computer technology, a machine learning based method is proposed in this paper to extract stress-strain curve of grey cast iron using sharp nanoindentation. Firstly, the average curve is achieved by the grid-design nanoindentation to avoid the influence of different phases on indentation results. The plastic behavior is considered as a power law function in this paper. Then, finite element method supports to generate a simulation data set, with full-factor and full-level design of constants of stress-strain relation. With the simulation data set, the support vector regression machine establishes a surrogate model to correlate the input (constants of stress-strain function) and output (the mean error between predicted and measured results). The best parameters of support vector machine are determined through grid search and cross-validation. PSO serves as the optimization algorithm to find the optimum of input related to the measured results, with an inertia factor to improve the local search ability. Finally, the simulation loading curve with the optimal constants provided by PSO perfectly fits the measured loading curve, which shows the effectiveness of the inverse method proposed in this paper.
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| 8. |
- Weng, Jian, et al.
(författare)
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An analytical method for continuously predicting mechanics and residual stress in fillet surface turning
- 2021
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Ingår i: Journal of Manufacturing Processes. - : Elsevier BV. - 1526-6125. ; 68, s. 1860-1879
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Tidskriftsartikel (refereegranskat)abstract
- A novel and effective approach for determining mechanics and residual stress when turning a component with curved surfaces is presented in this paper. This predictive approach is based on a three-dimensional analytical model to study the distributed mechanics and residual stress caused by vary cutting condition during the machining process. The variation of uncut chip area in this process can be divided into several stages based on different tool-workpiece contact and the discretization of cutting edge is conducted at an arbitrary tool position. The chip flow direction is calculated through the equilibrium of the incremental interaction forces. The cutting force can be determined by integrating the force components along the cutting edge, with each incremental force component obtained based on a fully analytical model. Distributed heat source intensity is considered to model the temperature rise at an arbitrary point in workpiece. The residual stress in curved surface machining is obtained considering the loading-unloading-relaxation procedure at the engagement of cutting edge and machined surface. Finally, Finite Element (FE) modeling and experiments are performed to validate the correctness and robustness of the analytical model proposed in this paper. The results of predicted chip flow direction, cutting force, temperature, and residual stress show good agreement with the simulated and measured results.
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| 9. |
- Weng, Zebin, et al.
(författare)
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Performance improvement of variable-angle annular thermoelectric generators considering different boundary conditions
- 2022
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Ingår i: Applied Energy. - : Elsevier BV. - 1872-9118 .- 0306-2619. ; 306
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Tidskriftsartikel (refereegranskat)abstract
- Practical applications of thermoelectric generators are impeded by their low thermoelectric conversion efficiency, and improving the efficiency is vital for the advancements of thermoelectric technology. In this paper, a novel method is proposed for the performance analysis and improvement of the annular thermoelectric generators with variable-angle PN legs (VATEGs). The influence of the PN leg angle on the output performance of the VATEG is investigated by introducing an angle function. Given the volume of the PN legs, the relationship of output performance between the VATEG and traditional constant-angle ATEG (CATEG) is established under different boundary conditions based on a proposed generic model of VATEG. The results are verified numerically using the finite element method. Using the model, it is shown that the output performance of the VATEG is significantly affected by the shape of the PN leg. Finally, the thermal stress on the PN leg is next investigated using a high-fidelity 3D model of the variable-angle PN legs implemented in COMSOL, and it is found that the shape difference has a considerable influence on the thermal stability of VATEG. Under the condition of constant heat flux on the hot side and constant temperature on the cold side of the thermoelectric modules, it shows that when the radius factor is 2, the output performance can be improved by 35% with the designed VATEG, at the expense of 30% higher maximum thermal stress on the PN legs.
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| 10. |
- Zhuang, Kejia, et al.
(författare)
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Numerical investigation of sequential cuts residual stress considering tool edge radius in machining of AISI 304 stainless steel
- 2022
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Ingår i: Simulation Modelling Practice and Theory. - : Elsevier BV. - 1569-190X. ; 118
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Tidskriftsartikel (refereegranskat)abstract
- Residual stress affects component performance, and the existence of pre-stress changes the residual stress of machined surfaces as well, emphasizing the importance of studying the evolution of residual stress in sequential cutting. This paper reports a numerical investigation of the machining-induced residual stress profile of sequential cuts for orthogonal cutting of AISI 304, considering the effects of edge radius and cutting depth. A Coupled Eulerian-Lagrangian (CEL) model is employed for the first time to stably simulate the evolution of residual stress of multiple sequential cuts. The effectiveness of the proposed method is verified by comparing the chip formation and surface residual stress between simulated and experimental results. The cutting force and cutting temperature, as well as mechanical and thermal loads, are extracted to explain the generation and evolution of residual stress in sequential cutting. It is found that the residual stress on the machined surfaces will decrease during sequential cutting, and a stable value can be reached after approximately six sequential cuts. With the progress of sequential cutting, a larger honed tool edge radius and cutting depth will lead to a slower reduction of residual stress.
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