GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • MDPI AG  (30)
  • 2020-2024  (30)
Material
Publisher
  • MDPI AG  (30)
Person/Organisation
Language
Years
  • 2020-2024  (30)
Year
  • 1
    Online Resource
    Online Resource
    Effects of Precipitation Change and Nitrogen and Phosphorus Additions on Traits and Abundance of Potentilla anserina in an Alpine Meadow
    MDPI AG ; 2022
    In:  Atmosphere Vol. 13, No. 11 ( 2022-11-02), p. 1820-
    Details
    In: Atmosphere, MDPI AG, Vol. 13, No. 11 ( 2022-11-02), p. 1820-
    Abstract: Changes in precipitation patterns and eutrophication can cause changes in plant traits and abundance, potentially affecting plant community structure and functions. Here, we studied responses of traits and abundance of Potentilla anserina to precipitation change and nitrogen (N) and phosphorus (P) additions, and the effect of traits on its abundance in an alpine meadow of the Qinghai-Tibet Plateau. We found that precipitation change and N and P additions significantly affected the mean value of traits such as specific leaf area (SLA), leaf dry matter content (LDMC), single leaf area, plant height and individual size, while only P addition significantly affected intraspecific variation of SLA and individual size. Increased precipitation and N and P additions shifted plant traits to more resource acquisitive, and increased plant abundance. Responses of plant traits to P addition were larger than that of N addition. Plant abundance was mainly affected by precipitation, and was limited by N or P dependent on precipitation conditions. In conclusions, our research shows that P. anserina can respond to environmental changes by changing its traits to improve its adaptability, potentially affecting community structure and ecosystem functions.
    Type of Medium: Online Resource
    ISSN: 2073-4433
    URL: Article
    DOI: 10.3390/atmos13111820
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2605928-9
    SSG: 23
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    Non-Rotationally Symmetric Field Mapping for Back-Scanned Step/Stare Imaging System
    MDPI AG ; 2020
    In:  Applied Sciences Vol. 10, No. 7 ( 2020-04-01), p. 2399-
    Details
    In: Applied Sciences, MDPI AG, Vol. 10, No. 7 ( 2020-04-01), p. 2399-
    Abstract: Step/stare imaging with focal plane arrays (FPAs) has become the main approach to achieve wide area coverage and high resolution imaging for long range targets. A fast steering mirror (FSM) is usually utilized to provide back-scanned motion to compensate for the image motion. However, the traditional optical design can just hold one field point relatively stable, typically the central or on-axis field point, on the FPA during back-scanning; all other field points may wander during the exposure due to imaging distortion characteristics of the optical system, which reduces the signal to noise ratio (SNR) of the target. Aiming toward this problem, this paper proposes a non-rotationally symmetric field mapping method for the back-scanned step/stare imaging system, which can make all field points stable on the FPA during back-scanning. First of all, the mathematical model of non-rotationally symmetric field mapping between object space and image space is established. Then, a back-scanned step/stare imaging system based on the model is designed, in which this non-rotationally symmetric mapping can be implemented with an afocal telescope including freeform lenses. Freeform lenses can produce an anamorphic aberration to adjust distortion characteristics of the optical system to control image wander on an FPA. Furthermore, the simulations verify the effectiveness of the method.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app10072399
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704225-X
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Dynamic Analysis of Cavitation Tip Vortex of Pump-Jet Propeller Based on DES
    MDPI AG ; 2020
    In:  Applied Sciences Vol. 10, No. 17 ( 2020-08-29), p. 5998-
    Details
    In: Applied Sciences, MDPI AG, Vol. 10, No. 17 ( 2020-08-29), p. 5998-
    Abstract: When a pump-jet propeller rotates at high speeds, a tip vortex is usually generated in the tip clearance region. This vortex interacts with the main channel fluid flow leading to the main energy loss of the rotor system. Moreover, operating at a high rotational speed can cause cavitation near the blades which may jeopardize the propulsion efficiency and induce noise. In order to effectively improve the propulsion efficiency of the pump-jet propeller, it is mandatory to research more about the energy loss mechanism in the tip clearance area. Due to the complex turbulence characteristics of the blade tip vortex, the widely used Reynolds averaged Navier–Stokes (RANS) method may not be able to accurately predict the multi-scale turbulent flow in the tip clearance. In this paper, an unsteady numerical simulation was conducted on the three-dimensional full flow field of a pump-jet propeller based on the DES (detached-eddy-simulation) turbulence model and the Z-G-B (Zwart–Gerber–Belamri) cavitation model. The simulation yielded the vortex shape and dynamic characteristics of the vortex core and the surrounding flow field in the tip clearance area. After cavitation occurred, the influence of cavitation bubbles on tip vortices was also studied. The results revealed two kinds of vortices in the tip clearance area, namely tip leakage vortex (TLV) and tip separation vortex (TSV). Slight cavitation at J = 1.02 led to low-frequency and high-frequency pulsation in the TLV vortex core. This occurrence of cavitation promotes the expansion and contraction of the tip vortex. Further, when the advance ratio changes into J = 0.73, a third type of vortex located between TLV and TSV appeared at the trailing edge which runs through the entire rotational cycle. This study has presented the dynamic characteristics of tip vortex including the relationship between cavitation bubbles and TLV inside the pump-jet propeller, which may provide a reference for the optimal design of future pump-jet propellers.
    Type of Medium: Online Resource
    ISSN: 2076-3417
    URL: Article
    DOI: 10.3390/app10175998
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2704225-X
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    RFLMDA: A Novel Reinforcement Learning-Based Computational Model for Human MicroRNA-Disease Association Prediction
    MDPI AG ; 2021
    In:  Biomolecules Vol. 11, No. 12 ( 2021-12-05), p. 1835-
    Details
    In: Biomolecules, MDPI AG, Vol. 11, No. 12 ( 2021-12-05), p. 1835-
    Abstract: Numerous studies have confirmed that microRNAs play a crucial role in the research of complex human diseases. Identifying the relationship between miRNAs and diseases is important for improving the treatment of complex diseases. However, traditional biological experiments are not without restrictions. It is an urgent necessity for computational simulation to predict unknown miRNA-disease associations. In this work, we combine Q-learning algorithm of reinforcement learning to propose a RFLMDA model, three submodels CMF, NRLMF, and LapRLS are fused via Q-learning algorithm to obtain the optimal weight S. The performance of RFLMDA was evaluated through five-fold cross-validation and local validation. As a result, the optimal weight is obtained as S (0.1735, 0.2913, 0.5352), and the AUC is 0.9416. By comparing the experiments with other methods, it is proved that RFLMDA model has better performance. For better validate the predictive performance of RFLMDA, we use eight diseases for local verification and carry out case study on three common human diseases. Consequently, all the top 50 miRNAs related to Colorectal Neoplasms and Breast Neoplasms have been confirmed. Among the top 50 miRNAs related to Colon Neoplasms, Gastric Neoplasms, Pancreatic Neoplasms, Kidney Neoplasms, Esophageal Neoplasms, and Lymphoma, we confirm 47, 41, 49, 46, 46 and 48 miRNAs respectively.
    Type of Medium: Online Resource
    ISSN: 2218-273X
    URL: Article
    DOI: 10.3390/biom11121835
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2701262-1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Analysis of Fluid-Structure Coupling Dynamic Characteristics of Centrifugal Pump Rotor System
    MDPI AG ; 2022
    In:  Energies Vol. 15, No. 6 ( 2022-03-15), p. 2133-
    Details
    In: Energies, MDPI AG, Vol. 15, No. 6 ( 2022-03-15), p. 2133-
    Abstract: Safety and reliable operation is one of the most important research areas for centrifugal pump systems, due to the interaction of complex flow, large structural load, and vibration caused by the operation of the impeller. To analyze the internal flow and impeller deformation of the centrifugal pump, the single-stage single-suction centrifugal pump titled IS100-80-160 was selected as the research object. Under the principle of single variable, the turbulent flow and structural response of three impellers designed by different parameters were calculated by CFX and ANSYS Workbench. A numerical simulation of steady flow at different flow rates of the centrifugal pump was carried out, and its hydraulic performance is consistent with the corresponding experimental results. By comparing the deformation of the impeller rotor system, it was found that the closed impeller has the worst stability with the best hydraulic performance; the impeller with split blades has the worst stability with the best hydraulic performance. This study could enhance the understanding of impeller FSI on centrifugal pump stability and provide a reference for improving the operational stability of centrifugal pumps.
    Type of Medium: Online Resource
    ISSN: 1996-1073
    URL: Article
    DOI: 10.3390/en15062133
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2437446-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    Broadband Microwave Photonic Mixer with Flexibly Tunable Phase Shift and Supporting Dispersion-Induced Power-Fading-Free Fiber Transmission
    MDPI AG ; 2023
    In:  Photonics Vol. 10, No. 4 ( 2023-04-11), p. 432-
    Details
    In: Photonics, MDPI AG, Vol. 10, No. 4 ( 2023-04-11), p. 432-
    Abstract: A broadband microwave photonic mixer with tunable phase shift and supporting dispersion-induced power-fading-free fiber transmission is proposed and demonstrated based on a dual-polarization dual-parallel Mach–Zehnder modulator (DP-DPMZM). In this scheme, the intermediate-frequency (IF)/radiofrequency (RF) signal and the local oscillation (LO) signal are applied to the four sub-MZMs biased at their minimum transmission points via a power splitter and a 90° hybrid coupler, respectively. Through mutual beating between the IF/RF and the LO modulation sidebands in a high-speed photodetector at the remote site, high-efficiency frequency conversion is achieved. The dispersion-induced power fading over long-distance fiber transmission is eliminated through setting the biased-induced phase difference between the parent-MZMs in the two sub-DPMZMs of the DP-DPMZM to be π/2. In addition, the phase shift of the frequency-converted signal can be continuously tuned over 360° through synchronously adjusting the bias voltages of the parent-MZMs in the two sub-DPMZMs. The proposed scheme is experimentally demonstrated, where a microwave photonic mixer with a 6-dB operation bandwidth of 40 GHz and supporting dispersion-induced power-fading-free transmission over 20 km SMF is realized. Meanwhile, a continuously tunable phase shift over 360° in the frequency range of 0.1 GHz to 29.9 GHz is achieved, where the power variation during phase tuning is smaller than 4 dB.
    Type of Medium: Online Resource
    ISSN: 2304-6732
    URL: Article
    DOI: 10.3390/photonics10040432
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2770002-1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Rapid Preparation of MWCNTs/Epoxy Resin Nanocomposites by Photoinduced Frontal Polymerization
    MDPI AG ; 2020
    In:  Materials Vol. 13, No. 24 ( 2020-12-21), p. 5838-
    Details
    In: Materials, MDPI AG, Vol. 13, No. 24 ( 2020-12-21), p. 5838-
    Abstract: Due to their excellent mechanical and thermal properties and medium resistance, epoxy/carbon nanotubes and nanocomposites have been widely used in many fields. However, the conventional thermosetting process is not only time- and energy-consuming, but also causes the agglomeration of nanofillers, which leads to unsatisfactory properties of the obtained composites. In this study, multi-walled carbon nanotubes (MWCNTs)/epoxy nanocomposites were prepared using UV photoinduced frontal polymerization (PIFP) in a rapid fashion. The addition of MWCNTs modified by a surface carboxylation reaction was found to enhance the impact strength and heat resistance of the epoxy matrix effectively. The experimental results indicate that with 0.4 wt % loading of modified MWCNTs, increases of 462.23% in the impact strength and 57.3 °C in the glass transition temperature Tg were achieved. A high-performance nanocomposite was prepared in only a few minutes using the PIFP approach. Considering its fast, energy-saving, and environmentally friendly production, the PIFP approach displays considerable potential in the field of the fast preparation, repair, and deep curing of nanocomposites and coatings.
    Type of Medium: Online Resource
    ISSN: 1996-1944
    URL: Article
    DOI: 10.3390/ma13245838
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2487261-1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 8
    Online Resource
    Online Resource
    Framework-Enhanced Electrochemiluminescence in Biosensing
    MDPI AG ; 2023
    In:  Chemosensors Vol. 11, No. 8 ( 2023-07-28), p. 422-
    Details
    In: Chemosensors, MDPI AG, Vol. 11, No. 8 ( 2023-07-28), p. 422-
    Abstract: Electrochemiluminescence (ECL) has attracted increasing attention owing to its intrinsic advantages of high sensitivity, good stability, and low background. Considering the fact that framework nanocrystals such as metal–organic frameworks and covalent organic frameworks have accurate molecular structures, a series of framework-based ECL platforms are developed for decoding emission fundamentals. The integration of fluorescent ligands into frameworks significantly improves the ECL properties due to the arrangement of molecules and intramolecular electron transfer. Moreover, the various framework topologies can be easily functionalized with the recognition elements to trace the targets for signal readout. These ECL enhancement strategies lead to a series of sensitive analytical methods for protein biomarkers, DNA, small biomolecules, and cells. In this review, we summarize recent advances in various functions of frameworks during the ECL process, and constructions of framework-based ECL platforms for biosensing. The framework-based ECL nanoemitters and enhancement mechanisms show both theoretical innovation and potential applications in designing ECL biosensing systems. Perspectives are also discussed, which may give a guideline for researchers in the fields of ECL biosensing and reticular materials.
    Type of Medium: Online Resource
    ISSN: 2227-9040
    URL: Article
    DOI: 10.3390/chemosensors11080422
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2704218-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 9
    Online Resource
    Online Resource
    Comparative Investigation on Hydrodynamic Performance of Pump-Jet Propulsion Designed by Direct and Inverse Design Methods
    MDPI AG ; 2021
    In:  Mathematics Vol. 9, No. 4 ( 2021-02-09), p. 343-
    Details
    In: Mathematics, MDPI AG, Vol. 9, No. 4 ( 2021-02-09), p. 343-
    Abstract: Pump-jet propulsion, a new propulsion technology, is primarily designed for underwater vehicles. Because of its concealment and excellent performance, it has been widely used, but due to its confidentiality and complexity, few studies have been published. To explore the relevant design theory of pump-jet propulsion with the aim of increasing its performance, in this study, we applied the direct and inverse design methods to construct a three-dimensional pump-jet model. The direct design method was carried out by comparing the lifting and lifting-line design methods, followed by further geometric optimization of the better model. In a numerical study using computational fluid dynamics (CFD) simulations, the Reynolds Averaged Naviere-Stokes (RANS) equations with SST k-ω turbulence model were solved in a cylindrical computational domain around the pump-jet propulsion device. A numerical investigation of the E779A propeller was carried out beforehand, using different advance ratios, in order to validate the accuracy of the numerical simulation method. The results show that for the direct method, although the model designed using the lifting-line method produced a greater thrust and the pump-jet designed using the lifting method was more efficient and stable, which is more suitable for small and medium underwater vehicles. When considering the inverse design method, the pump-jet propeller obviously accelerated the fluid, and the speed was obviously greater than that designed using the direct design method, while the turbulent kinetic energy in the flow field was higher, as well as the energy loss. Therefore, for small- and medium-sized underwater vehicles, if the priorities are high thrust and high efficiency, the inverse design method is the best option, whereas if stability and lower energy loss are preferred, the direct design method should be adopted.
    Type of Medium: Online Resource
    ISSN: 2227-7390
    URL: Article
    DOI: 10.3390/math9040343
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2704244-3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 10
    Online Resource
    Online Resource
    Characterization of Traditional Chinese Sesame Oil by Using Headspace Solid-Phase Microextraction/Gas Chromatography–Mass Spectrometry, Electronic Nose, Sensory Evaluation, and RapidOxy
    MDPI AG ; 2022
    In:  Foods Vol. 11, No. 22 ( 2022-11-08), p. 3555-
    Details
    In: Foods, MDPI AG, Vol. 11, No. 22 ( 2022-11-08), p. 3555-
    Abstract: Xiao Mo Xiang You (XMXY) is a traditional Chinese sesame oil variety that is obtained through a hot water flotation process. This unique process gives the oil a unique aroma, health benefits, and excellent product stability. Although XMXY is always the most expensive among all the sesame oil varieties, it is usually used as a flavoring in many traditional Chinese daily food products and is increasingly popular. In order to reveal the characteristics of the oil, the volatile components, sensory evaluation, and oxidation stability of five XMXY samples were, respectively, analyzed by using headspace solid-phase microextraction/gas chromatography–mass spectrometry, an electronic nose, sensory evaluation, and RapidOxy. Comparisons and multidimensional statistical analysis were also carried out to distinguish XMXY from roasted sesame oil (RSO) and cold-pressed sesame oil (CSO) samples. In total, 69 volatiles were identified from XMXY, RSO, and CSO samples. Some compounds possessed high odor activity value (OAV 〉 1) in XMXY, including heterocyclic compounds, phenols, and sulfur-containing compounds. Additionally, they were also the main volatile components that distinguish XMXY from RSO and CSO. Roasted and nutty aromas were the dominant aroma attributes of XMXY. XMXY had better flavor intensity and oxidation stability than the other two sesame oil samples. These results are very valuable for the quality control and product identification of traditional Chinese sesame oil.
    Type of Medium: Online Resource
    ISSN: 2304-8158
    URL: Article
    DOI: 10.3390/foods11223555
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2704223-6
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...