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Sökning: WFRF:(Zhang Zhi Yong) > (2015-2019)

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  • Wan, Cheng-Liang, et al. (författare)
  • Dynamics of slow electrons transmitting through straight glass capillary and tapered glass capillary
  • 2016
  • Ingår i: Wuli xuebao. - 1000-3290. ; 65:20
  • Tidskriftsartikel (refereegranskat)abstract
    • It has been found that the transmission rate of the electrons through insulating capillaries as a function of time/incident charge is not the same as that of the ions. The question arises that by using the electrons, if the negative charge patches can be formed to facilitate the transmission of the following electrons, thereby substantiating that the so-called guiding effect works also for electrons. This study aims to observe the time evolutions of the transmission of electrons through a straight glass tube and a tapered glass capillary. This will reveal the details of how and (or) if the negative charge patches can be formed when the electrons transport through them. In this work, a set of MCP/phosphor two-dimensional detection system based on Labview platform is developed to obtain the time evolution of the angular distribution of the transmitted electrons. The pulsed electron beams are obtained to test our detection system. The time evolution of the angular profile of 1.5 keV electrons transmitting through the glass tube/capillary is observed. The transmitted electrons are observed on the detector for a very short time and disappear for a time and then appear again for both the glass tube and tapered glass capillary, leading to an oscillation. The positive charge patches are formed in the insulating glass tube and tapered glass capillary since the secondary electron emission coefficient for the incident energy is larger than 1. It is due to the fact that fast discharge of the deposited charge leads to the increase of the transmission rate, while the fast blocking of the incident electrons due to the deposited positive charge leads to the decrease of the transmission rate. The geometrical configuration of the taper glass capillary tends to make the secondary electrons deposited at the exit part to form the negative patches that facilitate the transmission of electrons. This suggests that if the stable transmission needs to be reached for producing the electron micro-beam by using tapered glass capillaries, the steps must be taken to have the proper grounding and shielding of the glass capillaries and tubes. Our results show a difference in transmission through the insulating capillary between electrons and highly charged ions.
  • Qian, Li-Bing, et al. (författare)
  • Transmission of electrons through the conical glass capillary with the grounded conducting outer surface
  • 2017
  • Ingår i: Wuli xuebao. - 1000-3290. ; 66:12
  • Tidskriftsartikel (refereegranskat)abstract
    • The transmission of 1.5 keV-electrons through a conical glass capillary is reported. This study aims to understand the so-called guiding effect for the negatively charged particles (e.g. electrons). The guiding mechanism is understood quite well with positively charged particles in particular highly charged ions, but not clear with electrons, i. e., even the basic scheme mediated by the existence of negative charge patches to guide the electrons is still somewhat controversial.. The study of the charging-up dynamics causing the electrons transport inside the capillary will shed light on this issue. In order to perform this, a data acquisition system has been setup to follow the time evolution of the two-dimensional angular distribution of the transmitted electrons. The electrons are detected by the multi-channel plate (MCP) detector with a phosphor screen. The image from the phosphor screen is recorded by a charge-coupled device camera. The timing signals for the detected events are extracted from the back stack of the MCP detector and recorded by the data acquisition system, synchronized with the acquired images. The electron beam has a size of 0.5 mm x 0.5 mm and a divergence of less than 0.35.. The inner diameter of the straight part of the capillary is 1.2 mm and the exit diameter is 225 mu m. A small conducting aperture of 0.3 mm in diameter is placed at the entrance of the capillary. Two-dimensional angular distribution of the transmitted electrons through conical glass capillary and its time evolution are measured. The results show that the transmission rate decreases and reaches to a constant value for the completely discharged glass capillary with time going by. The centroid of the angular distribution moves to an asymptotic value while the width remains unchanged. These transmission characteristics are different from those indicated in our previous work (2016 Acta Phys: Si n: 65 204103). The difference originates from the different manipulations of the capillary outer surface. A conducting layer is coated on the outer surface of the capillary and grounded in this work. This isolates various discharge/charge channels and forms a new stable discharge channel. The transmission rate as a function of the tilt angle shows that the allowed transmission occurs at the tilt angle limited by the geometrical factors, i. e., the geometrical opening angle given by the aspect ratio as well as the beam divergence. The transmission characteristics suggest that most likely there are formed no negative patches to facilitate the electron transmission through the glass capillary at this selected beam energy. It is different from that of highly charged ions, where the formation of the charge patches prohibits the close collisions between the following ions and guides them out of the capillary.
  • Ding, Yong, et al. (författare)
  • Image quality assessment based on multi-order local features description, modeling and quantification
  • 2017
  • Ingår i: IEICE Transactions on Information and Systems. - The Institute of Electronics, Information and Communication Engineers. - 0916-8532. ; E100D:6, s. 1303-1315
  • Tidskriftsartikel (refereegranskat)abstract
    • Image quality assessment (IQA) plays an important role in quality monitoring, evaluation and optimization for image processing systems. However, current quality-Aware feature extraction methods for IQA can hardly balance accuracy and complexity. This paper introduces multi-order local description into image quality assessment for feature extraction. The first-order structure derivative and high-order discriminative information are integrated into local pattern representation to serve as the quality-Aware features. Then joint distributions of the local pattern representation are modeled by spatially enhanced histogram. Finally, the image quality degradation is estimated by quantifying the divergence between such distributions of the reference image and those of the distorted image. Experimental results demonstrate that the proposed method outperforms other state-of-The-Art approaches in consideration of not only accuracy that is consistent with human subjective evaluation, but also robustness and stability across different distortion types and various public databases. It provides a promising choice for image quality assessment development.
  • Qu, Yanhua, 1974-, et al. (författare)
  • Genetic responses to seasonalvariation in altitudinal stress: whole-genome resequencing ofgreat tit in eastern Himalayas
  • 2015
  • Ingår i: Scientific Reports. - 2045-2322. ; 5
  • Tidskriftsartikel (refereegranskat)abstract
    • Species that undertake altitudinal migrations are exposed to a considerable seasonal variationin oxygen levels and temperature. How they cope with this was studied in a population of greattit (Parus major) that breeds at high elevations and winters at lower elevations in the easternHimalayas. Comparison of population genomics of high altitudinal great tits and those living inlowlands revealed an accelerated genetic selection for carbohydrate energy metabolism (aminosugar, nucleotide sugar metabolism and insulin signaling pathways) and hypoxia response (PI3K-akt,mTOR and MAPK signaling pathways) in the high altitudinal population. The PI3K-akt, mTOR andMAPK pathways modulate the hypoxia-inducible factors, HIF-1α and VEGF protein expression thusindirectly regulate hypoxia induced angiogenesis, erythropoiesis and vasodilatation. The strategiesobserved in high altitudinal great tits differ from those described in a closely related species onthe Tibetan Plateau, the sedentary ground tit (Parus humilis). This species has enhanced selectionin lipid-specific metabolic pathways and hypoxia-inducible factor pathway (HIF-1). Comparativepopulation genomics also revealed selection for larger body size in high altitudinal great tits.
  • Tin, Adrienne, et al. (författare)
  • Target genes, variants, tissues and transcriptional pathways influencing human serum urate levels
  • 2019
  • Ingår i: Nature Genetics. - 1061-4036 .- 1546-1718. ; 51:10, s. 1459-1474
  • Tidskriftsartikel (refereegranskat)abstract
    • Elevated serum urate levels cause gout and correlate with cardiometabolic diseases via poorly understood mechanisms. We performed a trans-ancestry genome-wide association study of serum urate in 457,690 individuals, identifying 183 loci (147 previously unknown) that improve the prediction of gout in an independent cohort of 334,880 individuals. Serum urate showed significant genetic correlations with many cardiometabolic traits, with genetic causality analyses supporting a substantial role for pleiotropy. Enrichment analysis, fine-mapping of urate-associated loci and colocalization with gene expression in 47 tissues implicated the kidney and liver as the main target organs and prioritized potentially causal genes and variants, including the transcriptional master regulators in the liver and kidney, HNF1A and HNF4A. Experimental validation showed that HNF4A transactivated the promoter of ABCG2, encoding a major urate transporter, in kidney cells, and that HNF4A p.Thr139Ile is a functional variant. Transcriptional coregulation within and across organs may be a general mechanism underlying the observed pleiotropy between urate and cardiometabolic traits.
  • Zhu, Yin Fa, et al. (författare)
  • Experimental analysis on filter press and energy consumption performance of diaphragm press drying device in chemical post-processing integrated equipment
  • 2016
  • Ingår i: Case Studies in Thermal Engineering. - Elsevier. - 2214-157X. ; 7, s. 92-102
  • Tidskriftsartikel (refereegranskat)abstract
    • Higher efficiency, lower energy consumption and less pollution are become more and more important in chemical engineering. Post-process is one of the key parts for producing chemical productions. Thus, we develop a novel device, Chemical Post-Processing Integrated Equipment (CPPIE), which can deal with crystallization, filtration, washing and drying in the same tank by changing the position of it. Without the transfer during these processes, CPPIE have meaningful advantages compared to conventional devices. In this paper, the structure and the working procedure of CPPIE are introduced, and Diaphragm press drying device (DPDD) in CPPIE is further described. Then, the experimental setup is arranged. Its drying and energy consumption performances are experimentally investigated. The performance of DPDD is analyzed experimentally with theory to validate it can meet the requirements of industrial applications. Furthermore, the energy consumption for the whole processes is calculated with experimental data. Compared to CPPIE without DPDD, CPPIE with DPDD has energy conservation about 25%. This work presents the feasibility of CPPIE, the advantage of DPDD for drying process with lower energy consumption, which can be referenced for designing similar integrated equipment.
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