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Träfflista för sökning "WFRF:(Shi Liu) ;hsvcat:2"

Sökning: WFRF:(Shi Liu) > Teknik

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1.
  • Fenstermacher, M.E., et al. (författare)
  • DIII-D research advancing the physics basis for optimizing the tokamak approach to fusion energy
  • 2022
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:4
  • Tidskriftsartikel (refereegranskat)abstract
    • DIII-D physics research addresses critical challenges for the operation of ITER and the next generation of fusion energy devices. This is done through a focus on innovations to provide solutions for high performance long pulse operation, coupled with fundamental plasma physics understanding and model validation, to drive scenario development by integrating high performance core and boundary plasmas. Substantial increases in off-axis current drive efficiency from an innovative top launch system for EC power, and in pressure broadening for Alfven eigenmode control from a co-/counter-I p steerable off-axis neutral beam, all improve the prospects for optimization of future long pulse/steady state high performance tokamak operation. Fundamental studies into the modes that drive the evolution of the pedestal pressure profile and electron vs ion heat flux validate predictive models of pedestal recovery after ELMs. Understanding the physics mechanisms of ELM control and density pumpout by 3D magnetic perturbation fields leads to confident predictions for ITER and future devices. Validated modeling of high-Z shattered pellet injection for disruption mitigation, runaway electron dissipation, and techniques for disruption prediction and avoidance including machine learning, give confidence in handling disruptivity for future devices. For the non-nuclear phase of ITER, two actuators are identified to lower the L-H threshold power in hydrogen plasmas. With this physics understanding and suite of capabilities, a high poloidal beta optimized-core scenario with an internal transport barrier that projects nearly to Q = 10 in ITER at ∼8 MA was coupled to a detached divertor, and a near super H-mode optimized-pedestal scenario with co-I p beam injection was coupled to a radiative divertor. The hybrid core scenario was achieved directly, without the need for anomalous current diffusion, using off-axis current drive actuators. Also, a controller to assess proximity to stability limits and regulate β N in the ITER baseline scenario, based on plasma response to probing 3D fields, was demonstrated. Finally, innovative tokamak operation using a negative triangularity shape showed many attractive features for future pilot plant operation.
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2.
  • Xia, Yangyang, et al. (författare)
  • Prediction of bending strength of glass fiber reinforced methacrylate-based pipeline UV-CIPP rehabilitation materials based on machine learning
  • 2023
  • Ingår i: Tunnelling and Underground Space Technology. - : Elsevier. - 0886-7798 .- 1878-4364. ; 140
  • Tidskriftsartikel (refereegranskat)abstract
    • Ultraviolet cured-in-place-pipe (UV-CIPP) materials are commonly used in trenchless pipeline rehabilitation. Their bending strength is a crucial indicator to evaluate the curing quality. Studies show that this indicator is affected by multiple factors, including the curing time, UV lamp curing power, curing distance, and material thickness. Laboratory experiments have limitations in analyzing the effect of multiple factors on the bending strength of UV-CIPP materials and quantitatively predicting the optimum curing parameters. Aiming at resolving these shortcomings, resolve machine learning techniques were applied to predict the bending strength. In this regard, the surface curing reaction temperature monitoring data and three-point bending data of 30 groups of UV-CIPP material under the influence of different curing parameters were used as a dataset to predict the bending strength of UV-CIPP material. The results show that the influence degree of each factor on the bending strength of the UV-CIPP material, from high to low, is as follows: UV lamp power (−0.439), the temperature at the illuminated side (−0.392), curing time (−0.323), the temperature at the back side (−0.233), curing distance (0.143) and material thickness (−0.140). The best penalty parameter c (44.435) and width g (0.072) of the kernel function in the support vector machine (SVM) model were obtained using the genetic algorithm (GA) optimization, and the results were compared with the grey wolf optimizer (GWO) and particle swarm optimization (PSO). The performed analyses revealed that the developed GA-SVM model exhibits the best prediction results compared to other machine learning algorithms. The optimum bending strength of the UV-CIPP material used in this test is 294.77 MPa, which corresponds to the curing time, UV lamp power, curing distance, material thickness, light side temperature, and back side temperature of 7.59 min, 157.33 mW/cm2, 189.99 mm, 4.38 mm, 79.49 °C, and 76.59 °C, respectively.
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3.
  • Ma, Tian, et al. (författare)
  • Lipid engineering combined with systematic metabolic engineering of Saccharomyces cerevisiae for high-yield production of lycopene
  • 2019
  • Ingår i: Metabolic Engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 52, s. 134-142
  • Tidskriftsartikel (refereegranskat)abstract
    • Saccharomyces cerevisiae is an efficient host for natural-compound production and preferentially employed in academic studies and bioindustries. However, S. cerevisiae exhibits limited production capacity for lipophilic natural products, especially compounds that accumulate intracellularly, such as polyketides and carotenoids, with some engineered compounds displaying cytotoxicity. In this study, we used a nature-inspired strategy to establish an effective platform to improve lipid oil–triacylglycerol (TAG) metabolism and enable increased lycopene accumulation. Through systematic traditional engineering methods, we achieved relatively high-level production at 56.2 mg lycopene/g cell dry weight (cdw). To focus on TAG metabolism in order to increase lycopene accumulation, we overexpressed key genes associated with fatty acid synthesis and TAG production, followed by modulation of TAG fatty acyl composition by overexpressing a fatty acid desaturase (OLE1) and deletion of Seipin (FLD1), which regulates lipid-droplet size. Results showed that the engineered strain produced 70.5 mg lycopene/g cdw, a 25% increase relative to the original high-yield strain, with lycopene production reaching 2.37 g/L and 73.3 mg/g cdw in fed-batch fermentation and representing the highest lycopene yield in S. cerevisiae reported to date. These findings offer an effective strategy for extended systematic metabolic engineering through lipid engineering.
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4.
  • Qin, Ning, et al. (författare)
  • Increased CO 2 fixation enables high carbon-yield production of 3-hydroxypropionic acid in yeast
  • 2024
  • Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
  • Tidskriftsartikel (refereegranskat)abstract
    • CO2 fixation plays a key role to make biobased production cost competitive. Here, we use 3-hydroxypropionic acid (3-HP) to showcase how CO2 fixation enables approaching theoretical-yield production. Using genome-scale metabolic models to calculate the production envelope, we demonstrate that the provision of bicarbonate, formed from CO2, restricts previous attempts for high yield production of 3-HP. We thus develop multiple strategies for bicarbonate uptake, including the identification of Sul1 as a potential bicarbonate transporter, domain swapping of malonyl-CoA reductase, identification of Esbp6 as a potential 3-HP exporter, and deletion of Uga1 to prevent 3-HP degradation. The combined rational engineering increases 3-HP production from 0.14 g/L to 11.25 g/L in shake flask using 20 g/L glucose, approaching the maximum theoretical yield with concurrent biomass formation. The engineered yeast forms the basis for commercialization of bio-acrylic acid, while our CO2 fixation strategies pave the way for CO2 being used as the sole carbon source.
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5.
  • Tang, Liqui, et al. (författare)
  • Experimental and numerical investigations on the hybrid dowel and bonding steel plate joints for timber structures
  • 2020
  • Ingår i: Construction and Building Materials. - : Elsevier Ltd. - 0950-0618 .- 1879-0526. ; 265
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper summarizes the experimental and numerical investigations on an innovative hybrid joint for timber structures. A total of 12 hybrid dowel and bonding steel plate joints divided in four subgroups were investigated. Different parameters such as the presence of self-tapping screws and the surface treatment of the bonding steel plate, were studied. For two subgroups, a vulcanized rubber layer was applied to the bonding steel plate, before gluing it onto the timber surface. Monotonic tensile tests were carried out on the proposed joints and three replicates for each subgroup were constructed. The focus of this research has been on the load-carrying capacity, shear stress and slip stiffness of the proposed joints. Test results showed that the load-carrying capacity of the hybrid joints was much higher than that of similar screw joints. The introduction of the vulcanized rubber layer in the specimens leaded to the slight improvement of load-carrying capacity and the remarkable improvement of maximum slip. The comparisons between numerical and experimental results indicated that the proposed numerical model had a satisfactory agreement with experimental results and could be used to simulate this hybrid joints. The numerical analysis showed that the shear stress was concentrated in edge regions of the bond line for specimens without rubber layer. While the shear stress distribution became much more uniform for specimens with rubber layer. The research results showed that the bonding steel plate joints with 3.0 mm rubber layer were characterized by both high deformability and high load-carrying capacity.
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7.
  • Lin, Zhenquan, et al. (författare)
  • Characterization of cross-species transcription and splicing from Penicillium to Saccharomyces cerevisiae
  • 2021
  • Ingår i: Journal of Industrial Microbiology and Biotechnology. - : Oxford University Press (OUP). - 1367-5435 .- 1476-5535. ; 48:9-10
  • Tidskriftsartikel (refereegranskat)abstract
    • Heterologous expression of eukaryotic gene clusters in yeast has been widely used for producing high-value chemicals and bioactive secondary metabolites. However, eukaryotic transcription cis-elements are still undercharacterized, and the cross-species expression mechanism remains poorly understood. Here we used the whole expression unit (including original promoter, terminator, and open reading frame with introns) of orotidine 5'-monophosphate decarboxylases from 14 Penicillium species as a showcase, and analyzed their cross-species expression in Saccharomyces cerevisiae. We found that pyrG promoters from the Penicillium species could drive URA3 expression in yeast, and that inefficient cross-species splicing of Penicillium introns might result in weak cross-species expression. Thus, this study demonstrates cross-species expression from Penicillium to yeast, and sheds light on the opportunities and challenges of cross-species expression of fungi expression units and gene clusters in yeast without refactoring for novel natural product discovery.
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8.
  • Shi, B., et al. (författare)
  • Short- and long-term performance of bonding steel-plate joints for timber structures
  • 2020
  • Ingår i: Construction and Building Materials. - : Elsevier Ltd. - 0950-0618 .- 1879-0526. ; 240
  • Tidskriftsartikel (refereegranskat)abstract
    • The long-term performance of bonding steel-plate joints in controlled environmental conditions in this work. The bonding steel-plate joint consists of a steel plate with a vulcanized rubber layer and six wood screws. The vulcanized rubber layer is intended to improve the ductility of bonding steel-plate joints. Six pull-pull specimens were tested in order to determine the short-term load bearing capacity of bonding steel-plate joints, and the dimension of the shear plane of each bond line was 80 mm × 80 mm. A total of 12 specimens were employed in long-term tests. Two stress levels, including the 30% and 60% of ultimate bearing capacity, were adopted. All specimens were monitored over 800 days except that one series of specimens with 0.6 stress level which failed during the long-term tests. At the end of 858-day loading, the average slip at the connection for the specimens with 30% and 60% stress level were 0.623 mm and 0.939 mm, respectively. The creep coefficients were calculated according to the measured experimental data. The Burger's model, two term and six term Kelvin's model were adopted to fit the curves of creep coefficients, and then predict the creep slip of joints in the duration of service. The long-term slip stiffness and the ratio of stiffness loss are calculated according to experimental curves, and are predicted on the basis of the prediction results of creep coefficients through by six term Kelvin's model.
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9.
  • Liu, Weihua, et al. (författare)
  • Cooperate or not? Strategic analysis of platform interactions considering market power and precision marketing
  • 2021
  • Ingår i: Transportation Research Part E. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1366-5545 .- 1878-5794. ; 154
  • Tidskriftsartikel (refereegranskat)abstract
    • In order to increase market share and enhance business competitiveness, comprehensive retail platforms (CRPs), such as Taobao.com and JD.com, are currently cooperating with social service platforms (SSPs), such as TikTok and Meiyou. Therefore, more research attention needs to be paid to such platform supply chains. To this end, this study develops stylized models to explore the impacts of the market power of an SSP and the precision marketing of a CRP on platform cooperation. Our major research findings include the following. First, we investigate the equilibrium strategy and find that if the CRPs commission rate is low (high), cooperation becomes the equilibrium strategy when the SSPs market power is low (high). Second, in most cases, market power will affect the equilibrium strategy with a change in the commission rate. However, in a certain range of commission rates, the equilibrium strategy remains unchanged. That is, market power has an "invalidation effect" on the equilibrium strategy. Finally, we find that as the commission rate increases, precision marketing reduces the willingness of supply chain members to implement platform cooperation. However, when the commission rate is low, precision marketing stimulates cooperation between platforms. The study results provide guidelines for improving the cooperation between CRPs and SSPs.
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10.
  • Rong, X., et al. (författare)
  • Experimental study on a multi-evaporator mutual defrosting system for air source heat pumps
  • 2023
  • Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 332
  • Tidskriftsartikel (refereegranskat)abstract
    • Air source heat pumps (ASHPs) are prone to frost when heating in a low-temperature and high-humidity environment, which deteriorates the heating performance of the unit. In this study, a new multi-evaporator mutual defrosting (MEMD) system was proposed to overcome the disadvantages of traditional defrosting methods: intermittent heating and inefficient defrosting. To validate the performance of the proposed defrosting technology, comparative tests were conducted in various outdoor environmental conditions. The experimental results showed that the MEMD system could continuously heat water during the defrosting period. In five experimental conditions, the MEMD system exhibited a lower water temperature drop range (2.1–2.8 °C) than that of a traditional reverse-cycle defrosting (RCD) system (6.0–7.3 °C). Due to the effective utilization of heat production during the heating period, the effective heat power (qe) of the unit increased by 0.7–1.4 kW, and the heat loss coefficient (HLC) of frosting and defrosting increased by an average of 6 % in the five experimental conditions, effectively reducing the heating capacity loss of the unit caused by defrosting. While defrosting, the MEMD system was able to utilize the remaining evaporators to absorb heat from the air and then deliver it to the defrosting evaporator. The equivalent defrosting energy efficiency (COPd) of the MEMD system was 17.5 % greater than that of the RCD system on average. During the heating and defrosting cycle, the energy saved when defrosting could increase the cycle coefficient of performance (CCOP) of heating by 3.7 %. 
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