| 1. |
- He, Li, et al.
(författare)
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In silico promoter analysis and functional validation identify CmZFH, the co-regulator of hypoxia-responsive genes CmScylla and CmLPCAT
- 2022
-
Ingår i: Insect Biochemistry and Molecular Biology. - : Elsevier. - 0965-1748 .- 1879-0240. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- Oxygen (O2) plays an essential role in aerobic organisms including terrestrial insects. Under hypoxic stress, the cowpea bruchid (Callosobruchus maculatus) ceases feeding and growth. However, larvae, particularly 4th instar larvae exhibit very high tolerance to hypoxia and can recover normal growth once brought to normoxia. To better understand the molecular mechanism that enables insects to cope with low O2 stress, we performed RNA-seq to distinguish hypoxia-responsive genes in midguts and subsequently identified potential common cis-elements in promoters of hypoxia-induced and -repressed genes, respectively. Selected elements were subjected to gel-shift and transient transfection assays to confirm their cis-regulatory function. Of these putative common cis-elements, AREB6 appeared to regulate the expression of CmLPCAT and CmScylla, two hypoxia-induced genes. CmZFH, the putative AREB6-binding protein, was hypoxia-inducible. Transient expression of CmZFH in Drosophila S2 cells activated CmLPCAT and CmScylla, and their induction was likely through interaction of CmZFH with AREB6. Binding to AREB6 was further confirmed by bacterially expressed CmZFH recombinant protein. Deletion analyses indicated that the N-terminal zinc-finger cluster of CmZFH was the key AREB6-binding domain. Through in silico and experimental exploration, we discovered novel transcriptional regulatory components associated with gene expression dynamics under hypoxia that facilitated insect survival.
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| 2. |
- Thoma, B, et al.
(författare)
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An international, interprofessional investigation of the self-reported podcast listening habits of emergency clinicians: A METRIQ Study
- 2020
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Ingår i: CJEM. - : Springer Science and Business Media LLC. - 1481-8043 .- 1481-8035. ; 22:1, s. 112-117
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Tidskriftsartikel (refereegranskat)abstract
- ObjectivesPodcasts are increasingly being used for medical education. A deeper understanding of usage patterns would inform both producers and researchers of medical podcasts. We aimed to determine how and why podcasts are used by emergency medicine and critical care clinicians.MethodsAn international interprofessional sample (medical students, residents, physicians, nurses, physician assistants, and paramedics) was recruited through direct contact and a multimodal social media (Twitter and Facebook) campaign. Each participant completed a survey outlining how and why they utilize medical podcasts. Recruitment materials included an infographic and study website.Results390 participants from 33 countries and 4 professions (medicine, nursing, paramedicine, physician assistant) completed the survey. Participants most frequently listened to medical podcasts to review new literature (75.8%), learn core material (75.1%), and refresh memory (71.8%). The majority (62.6%) were aware of the ability to listen at increased speeds, but most (76.9%) listened at 1.0 x (normal) speed. All but 25 (6.4%) participants concurrently performed other tasks while listening. Driving (72.3%), exercising (39.7%), and completing chores (39.2%) were the most common. A minority of participants used active learning techniques such as pausing, rewinding, and replaying segments of the podcast. Very few listened to podcasts multiple times.ConclusionsAn international cohort of emergency clinicians use medical podcasts predominantly for learning. Their listening habits (rarely employing active learning strategies and frequently performing concurrent tasks) may not support this goal. Further exploration of the impact of these activities on learning from podcasts is warranted.
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| 3. |
- Arzoumanian, Doris, et al.
(författare)
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Dust polarized emission observations of NGC 6334: BISTRO reveals the details of the complex but organized magnetic field structure of the high-mass star-forming hub-filament network
- 2021
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 647
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Tidskriftsartikel (refereegranskat)abstract
- Context. Molecular filaments and hubs have received special attention recently thanks to new studies showing their key role in star formation. While the (column) density and velocity structures of both filaments and hubs have been carefully studied, their magnetic field (B-field) properties have yet to be characterized. Consequently, the role of B-fields in the formation and evolution of hub-filament systems is not well constrained. Aims. We aim to understand the role of the B-field and its interplay with turbulence and gravity in the dynamical evolution of the NGC 6334 filament network that harbours cluster-forming hubs and high-mass star formation. Methods. We present new observations of the dust polarized emission at 850 μm toward the 2 pc × 10 pc map of NGC 6334 at a spatial resolution of 0.09 pc obtained with the James Clerk Maxwell Telescope (JCMT) as part of the B-field In STar-forming Region Observations (BISTRO) survey. We study the distribution and dispersion of the polarized intensity (PI), the polarization fraction (PF), and the plane-of-The-sky B-field angle (χB_POS) toward the whole region, along the 10 pc-long ridge and along the sub-filaments connected to the ridge and the hubs. We derived the power spectra of the intensity and χBPOS along the ridge crest and compared them with the results obtained from simulated filaments. Results. The observations span 3 orders of magnitude in Stokes I and PI and 2 orders of magnitude in PF (from 0.2 to 20%). A large scatter in PI and PF is observed for a given value of I. Our analyses show a complex B-field structure when observed over the whole region ( 10 pc); however, at smaller scales (1 pc), χBPOS varies coherently along the crests of the filament network. The observed power spectrum of χBPOS can be well represented with a power law function with a slope of-1.33 ± 0.23, which is 20% shallower than that of I. We find that this result is compatible with the properties of simulated filaments and may indicate the physical processes at play in the formation and evolution of star-forming filaments. Along the sub-filaments, χBPOS rotates frombeing mostly perpendicular or randomly oriented with respect to the crests to mostly parallel as the sub-filaments merge with the ridge and hubs. This variation of the B-field structure along the sub-filaments may be tracing local velocity flows of infalling matter in the ridge and hubs. Our analysis also suggests a variation in the energy balance along the crests of these sub-filaments, from magnetically critical or supercritical at their far ends to magnetically subcritical near the ridge and hubs. We also detect an increase in PF toward the high-column density (NH2 â 1023 cm-2) star cluster-forming hubs. These latter large PF values may be explained by the increase in grain alignment efficiency due to stellar radiation from the newborn stars, combined with an ordered B-field structure. Conclusions. These observational results reveal for the first time the characteristics of the small-scale (down to 0.1 pc) B-field structure of a 10 pc-long hub-filament system. Our analyses show variations in the polarization properties along the sub-filaments that may be tracing the evolution of their physical properties during their interaction with the ridge and hubs. We also detect an impact of feedback from young high-mass stars on the local B-field structure and the polarization properties, which could put constraints on possible models for dust grain alignment and provide important hints as to the interplay between the star formation activity and interstellar B-fields.
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| 4. |
- Bai, Fan, et al.
(författare)
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Application of similarity theory in modeling the output characteristics of proton exchange membrane fuel cell
- 2021
-
Ingår i: International journal of hydrogen energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0360-3199 .- 1879-3487. ; 46:74, s. 36940-36953
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Tidskriftsartikel (refereegranskat)abstract
- Proton Exchange Membrane Fuel Cell (PEMFC) has attracted widespread interest. In the present work, similarity analysis is adopted for a three-dimensional single-phase isothermal model of PEMFC to derive similarity criteria. Seven kinds of input criteria (Pi(1) similar to Pi(7)) are obtained, relevant to the fluid flow, pressure drop, flow resistance in a porous medium, activity loss, diffusion mass transfer, convective mass transfer and ohmic loss in PEMFC respectively. Dimensionless voltage and dimensionless current density are defined as two output criteria. Numerical verifications show that if the seven criteria keep their individual values with their components vary in a wide range, the dimensionless polarization curves keep the same with a deviation about 1%, showing the validity and feasibility of the present analysis. From the effect on the dimensionless polarization curve, sensibility analysis shows that the seven criteria can be divided into three categories: strong (Pi(4) and Pi(7), -94.9% similar to +349.2%), mild to minor (Pi(5) and Pi(6), -4.5% similar to +5.0%), and negligible (Pi(1), Pi(2) and Pi(3), -1.2% similar to +1.1%). The similarity analysis approach can greatly save computation time in modeling the output characteristics of PEMFC. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.
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| 5. |
- Ching, Tao-Chung, et al.
(författare)
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The JCMT BISTRO-2 Survey: Magnetic Fields of the Massive DR21 Filament
- 2022
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 941:2
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Tidskriftsartikel (refereegranskat)abstract
- We present 850 mu m dust polarization observations of the massive DR21 filament from the B-fields In STar-forming Region Observations (BISTRO) survey, using the POL-2 polarimeter and the SCUBA-2 camera on the James Clerk Maxwell Telescope. We detect ordered magnetic fields perpendicular to the parsec-scale ridge of the DR21 main filament. In the subfilaments, the magnetic fields are mainly parallel to the filamentary structures and smoothly connect to the magnetic fields of the main filament. We compare the POL-2 and Planck dust polarization observations to study the magnetic field structures of the DR21 filament on 0.1-10 pc scales. The magnetic fields revealed in the Planck data are well-aligned with those of the POL-2 data, indicating a smooth variation of magnetic fields from large to small scales. The plane-of-sky magnetic field strengths derived from angular dispersion functions of dust polarization are 0.6-1.0 mG in the DR21 filament and similar to 0.1 mG in the surrounding ambient gas. The mass-to-flux ratios are found to be magnetically supercritical in the filament and slightly subcritical to nearly critical in the ambient gas. The alignment between column density structures and magnetic fields changes from random alignment in the low-density ambient gas probed by Planck to mostly perpendicular in the high-density main filament probed by James Clerk Maxwell Telescope. The magnetic field structures of the DR21 filament are in agreement with MHD simulations of a strongly magnetized medium, suggesting that magnetic fields play an important role in shaping the DR21 main filament and subfilaments.
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| 6. |
- Dai, Lei, et al.
(författare)
-
AME : A Cross-Scale Constellation of CubeSats to Explore Magnetic Reconnection in the Solar-Terrestrial Relation
- 2020
-
Ingår i: Frontiers in Physics. - : Frontiers Media SA. - 2296-424X. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- A major subset of solar-terrestrial relations, responsible, in particular, for the driver of space weather phenomena, is the interaction between the Earth's magnetosphere and the solar wind. As one of the most important modes of the solar-wind-magnetosphere interaction, magnetic reconnection regulates the energy transport and energy release in the solar-terrestrial relation. In situ measurements in the near-Earth space are crucial for understanding magnetic reconnection. Past and existing spacecraft constellation missions mainly focus on the measurement of reconnection on plasma kinetic-scales. Resolving the macro-scale and cross-scale aspects of magnetic reconnection is necessary for accurate assessment and predictions of its role in the context of space weather. Here, we propose the AME (self-Adaptive Magnetic reconnection Explorer) mission consisting of a cross-scale constellation of 12+ CubeSats and one mother satellite. Each CubeSat is equipped with instruments to measure magnetic fields and thermal plasma particles. With multiple CubeSats, the AME constellation is intended to make simultaneous measurements at multiple scales, capable of exploring cross-scale plasma processes ranging from kinetic scale to macro scale.
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| 7. |
- Doi, Yasuo, et al.
(författare)
-
The JCMT BISTRO Survey: Magnetic Fields Associated with a Network of Filaments in NGC 1333
- 2020
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 899:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present new observations of the active star formation region NGC 1333 in the Perseus molecular cloud complex from the James Clerk Maxwell Telescope B-Fields In Star-forming Region Observations (BISTRO) survey with the POL-2 instrument. The BISTRO data cover the entire NGC 1333 complex (∼1.5 pc ? 2 pc) at 0.02 pc resolution and spatially resolve the polarized emission from individual filamentary structures for the first time. The inferred magnetic field structure is complex as a whole, with each individual filament aligned at different position angles relative to the local field orientation. We combine the BISTRO data with low- and high- resolution data derived from Planck and interferometers to study the multiscale magnetic field structure in this region. The magnetic field morphology drastically changes below a scale of ∼1 pc and remains continuous from the scales of filaments (∼0.1 pc) to that of protostellar envelopes (∼0.005 pc or ∼1000 au). Finally, we construct simple models in which we assume that the magnetic field is always perpendicular to the long axis of the filaments. We demonstrate that the observed variation of the relative orientation between the filament axes and the magnetic field angles are well reproduced by this model, taking into account the projection effects of the magnetic field and filaments relative to the plane of the sky. These projection effects may explain the apparent complexity of the magnetic field structure observed at the resolution of BISTRO data toward the filament network.
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| 8. |
- Eswaraiah, Chakali, et al.
(författare)
-
The JCMT BISTRO Survey: Revealing the Diverse Magnetic Field Morphologies in Taurus Dense Cores with Sensitive Submillimeter Polarimetry
- 2021
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 912:2
-
Tidskriftsartikel (refereegranskat)abstract
- We have obtained sensitive dust continuum polarization observations at 850 μm in the B213 region of Taurus using POL-2 on SCUBA-2 at the James Clerk Maxwell Telescope as part of the B-fields in STar-forming Region Observations (BISTRO) survey. These observations allow us to probe magnetic field (B-field) at high spatial resolution (∼2000 au or ∼0.01 pc at 140 pc) in two protostellar cores (K04166 and K04169) and one prestellar core (Miz-8b) that lie within the B213 filament. Using the Davis-Chandrasekhar-Fermi method, we estimate the B-field strengths in K04166, K04169, and Miz-8b to be 38 ± 14, 44 ± 16, and 12 ± 5 μG, respectively. These cores show distinct mean B-field orientations. The B-field in K04166 is well ordered and aligned parallel to the orientations of the core minor axis, outflows, core rotation axis, and large-scale uniform B-field, in accordance with magnetically regulated star formation via ambipolar diffusion taking place in K04166. The B-field in K04169 is found to be ordered but oriented nearly perpendicular to the core minor axis and large-scale B-field and not well correlated with other axes. In contrast, Miz-8b exhibits a disordered B-field that shows no preferred alignment with the core minor axis or large-scale field. We found that only one core, K04166, retains a memory of the large-scale uniform B-field. The other two cores, K04169 and Miz-8b, are decoupled from the large-scale field. Such a complex B-field configuration could be caused by gas inflow onto the filament, even in the presence of a substantial magnetic flux.
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| 9. |
- Han, L., et al.
(författare)
-
Cell transcriptomic atlas of the non-human primate Macaca fascicularis
- 2022
-
Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 604:7907, s. 723-731
-
Tidskriftsartikel (refereegranskat)abstract
- Studying tissue composition and function in non-human primates (NHPs) is crucial to understand the nature of our own species. Here we present a large-scale cell transcriptomic atlas that encompasses over 1 million cells from 45 tissues of the adult NHP Macaca fascicularis. This dataset provides a vast annotated resource to study a species phylogenetically close to humans. To demonstrate the utility of the atlas, we have reconstructed the cell–cell interaction networks that drive Wnt signalling across the body, mapped the distribution of receptors and co-receptors for viruses causing human infectious diseases, and intersected our data with human genetic disease orthologues to establish potential clinical associations. Our M. fascicularis cell atlas constitutes an essential reference for future studies in humans and NHPs.
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| 10. |
- Huang, Hua, 1986-, et al.
(författare)
-
ELTD1-deletion reduces vascular abnormality and improves T-cell recruitment after PD-1 blockade in glioma.
- 2021
-
Ingår i: Neuro-Oncology. - : Oxford University Press. - 1522-8517 .- 1523-5866. ; 24:3, s. 398-411
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Tumor vessels in glioma are molecularly and functionally abnormal, contributing to treatment resistance. Proteins differentially expressed in glioma vessels can change vessel phenotype and be targeted for therapy. ELTD1 (Adgrl4) is an orphan member of the adhesion G-protein-coupled receptor family upregulated in glioma vessels, and has been suggested as a potential therapeutic target. However, the role of ELTD1 in regulating vessel function in glioblastoma is poorly understood.METHODS: ELTD1 expression in human gliomas and its association with patient survival was determined using tissue microarrays and public databases. The role of ELTD1 in regulating tumor vessel phenotype was analyzed using orthotopic glioma models and ELTD1 -/- mice. Endothelial cells isolated from murine gliomas were transcriptionally profiled to determine differentially expressed genes and pathways. The consequence of ELTD1-deletion on glioma immunity was determined by treating tumor bearing mice with PD-1-blocking antibodies.RESULTS: ELTD1 levels were upregulated in human glioma vessels, increased with tumor malignancy, and were associated with poor patient survival. Progression of orthotopic gliomas was not affected by ELTD1-deletion, however, tumor vascular function was improved in ELTD1 -/- mice. Bioinformatic analysis of differentially expressed genes indicated increased inflammatory response and decreased proliferation in tumor endothelium in ELTD1 -/- mice. Consistent with an enhanced inflammatory response, ELTD1-deletion improved T-cell infiltration in GL261-bearing mice after PD-1 checkpoint blockade.CONCLUSION: Our data demonstrate that ELTD1 participates in inducing vascular dysfunction in glioma, and suggests that targeting of ELTD1 may normalize the vessels and improve the response to immunotherapy.
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| 11. |
- Hwang, Jihye, et al.
(författare)
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The JCMT BISTRO Survey: A Spiral Magnetic Field in a Hub-filament Structure, Monoceros R2
- 2022
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 941:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present and analyze observations of polarized dust emission at 850 μm toward the central 1 × 1 pc hub-filament structure of Monoceros R2 (Mon R2). The data are obtained with SCUBA-2/POL-2 on the James Clerk Maxwell Telescope (JCMT) as part of the B-fields in Star-forming Region Observations survey. The orientations of the magnetic field follow the spiral structure of Mon R2, which are well described by an axisymmetric magnetic field model. We estimate the turbulent component of the magnetic field using the angle difference between our observations and the best-fit model of the underlying large-scale mean magnetic field. This estimate is used to calculate the magnetic field strength using the Davis–Chandrasekhar–Fermi method, for which we also obtain the distribution of volume density and velocity dispersion using a column density map derived from Herschel data and the C18O (J = 3 - 2) data taken with HARP on the JCMT, respectively. We make maps of magnetic field strengths and mass-to-flux ratios, finding that magnetic field strengths vary from 0.02 to 3.64 mG with a mean value of 1.0 ± 0.06 mG, and the mean critical mass-to-flux ratio is 0.47 ± 0.02. Additionally, the mean Alfvén Mach number is 0.35 ± 0.01. This suggests that, in Mon R2, the magnetic fields provide resistance against large-scale gravitational collapse, and the magnetic pressure exceeds the turbulent pressure. We also investigate the properties of each filament in Mon R2. Most of the filaments are aligned along the magnetic field direction and are magnetically subcritical.
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| 12. |
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| 13. |
- Ji, Yanzhu, et al.
(författare)
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Orthologous microsatellites, transposable elements, and DNA deletions correlate with generation time and body mass in neoavian birds
- 2022
-
Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 8:35
-
Tidskriftsartikel (refereegranskat)abstract
- The rate of mutation accumulation in germline cells can be affected by cell replication and/or DNA damage, which are further related to life history traits such as generation time and body mass. Leveraging the existing datasets of 233 neoavian bird species, here, we investigated whether generation time and body mass contribute to the interspecific variation of orthologous microsatellite length, transposable element (TE) length, and deletion length and how these genomic attributes affect genome sizes. In nonpasserines, we found that generation time is correlated to both orthologous microsatellite length and TE length, and body mass is negatively correlated to DNA deletions. These patterns are less pronounced in passerines. In all species, we found that DNA deletions relate to genome size similarly as TE length, suggesting a role of body mass dynamics in genome evolution. Our results indicate that generation time and body mass shape the evolution of genomic attributes in neoavian birds.
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| 14. |
- Karoly, Janik, et al.
(författare)
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The JCMT BISTRO Survey: Studying the Complex Magnetic Field of L43
- 2023
-
Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 952:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present observations of polarized dust emission at 850 mu m from the L43 molecular cloud, which sits in the Ophiuchus cloud complex. The data were taken using SCUBA-2/POL-2 on the James Clerk Maxwell Telescope as a part of the BISTRO large program. L43 is a dense (N-H2 similar to 10(22) - 10(23) cm(-2)) complex molecular cloud with a submillimeter-bright starless core and two protostellar sources. There appears to be an evolutionary gradient along the isolated filament that L43 is embedded within, with the most evolved source closest to the Sco OB2 association. One of the protostars drives a CO outflow that has created a cavity to the southeast. We see a magnetic field that appears to be aligned with the cavity walls of the outflow, suggesting interaction with the outflow. We also find a magnetic field strength of up to similar to 160 +/- 30 mu G in the main starless core and up to similar to 90 +/- 40 mu G in the more diffuse, extended region. These field strengths give magnetically super- and subcritical values, respectively, and both are found to be roughly trans-Alfvenic. We also present a new method of data reduction for these denser but fainter objects like starless cores.
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| 15. |
- Kong, Long, et al.
(författare)
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An overview of generic tools for information-theoretic secrecy performance analysis over wiretap fading channels
- 2021
-
Ingår i: EURASIP Journal on Wireless Communications and Networking. - : Springer Nature. - 1687-1472 .- 1687-1499. ; 2021:1
-
Tidskriftsartikel (refereegranskat)abstract
- Physical layer security (PLS) has been proposed to afford an extra layer of security on top of the conventional cryptographic techniques. Unlike the conventional complexity-based cryptographic techniques at the upper layers, physical layer security exploits the characteristics of wireless channels, e.g., fading, noise, interference, etc., to enhance wireless security. It is proved that secure transmission can benefit from fading channels. Accordingly, numerous researchers have explored what fading can offer for physical layer security, especially the investigation of physical layer security over wiretap fading channels. Therefore, this paper aims at reviewing the existing and ongoing research works on this topic. More specifically, we present a classification of research works in terms of the four categories of fading models: (i) small-scale, (ii) large-scale, (iii) composite, and (iv) cascaded. To elaborate these fading models with a generic and flexible tool, three promising candidates, including the mixture gamma (MG), mixture of Gaussian (MoG), and Fox’s H-function distributions, are comprehensively examined and compared. Their advantages and limitations are further demonstrated via security performance metrics, which are designed as vivid indicators to measure how perfect secrecy is ensured. Two clusters of secrecy metrics, namely (i) secrecy outage probability (SOP), and the lower bound of SOP; and (ii) the probability of nonzero secrecy capacity (PNZ), the intercept probability, average secrecy capacity (ASC), and ergodic secrecy capacity, are displayed and, respectively, deployed in passive and active eavesdropping scenarios. Apart from those, revisiting the secrecy enhancement techniques based on Wyner’s wiretap model, the on-off transmission scheme, jamming approach, antenna selection, and security region are discussed.
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| 16. |
- Kwon, Woojin, et al.
(författare)
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B-fields in Star-forming Region Observations (BISTRO): Magnetic Fields in the Filamentary Structures of Serpens Main
- 2022
-
Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 926:2
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Tidskriftsartikel (refereegranskat)abstract
- We present 850 mu m polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope as part of the B-fields In STar-forming Region Observations survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less-dense filamentary structures where NH2 < 0.93 x 10(22) cm(-2) (magnetic fields perpendicular to density gradients), while they are perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to density gradients again at NH2 approximate to 4.6 x 10(22) NH2 approximate to 16 x 10(22) cm(-2), magnetic fields change back to being parallel to density gradients once again, which can be understood to be due to magnetic fields being dragged in by infalling material. In addition, we estimate the magnetic field strengths of the filaments (B-POS = 60-300 mu G)) using the Davis-Chandrasekhar-Fermi method and discuss whether the filaments are gravitationally unstable based on magnetic field and turbulence energy densities.
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| 17. |
- Lei, Lei, et al.
(författare)
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A building energy consumption prediction model based on rough set theory and deep learning algorithms
- 2021
-
Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 240
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Tidskriftsartikel (refereegranskat)abstract
- The efficient and accurate prediction of building energy consumption can improve the management of power systems. In this paper, the rough set theory was used to reduce the redundant influencing factors of building energy consumption and find the critical factors of building energy consumption. These key factors were then used as the input of a deep neural network with a & ldquo;deep & rdquo; architecture and powerful capabilities in extracting features. Building energy consumption is output of the deep neural network. This study collected data from 100 civil public buildings for rough set reduction, and then collected data from a laboratory building of a university in Dalian for nearly a year to train and test deep neural net-works. The test included both the short-term and medium-term predictions of building energy consump-tion. The prediction results of the deep neural network were compared with that of the back propagation neural network, Elman neural network and fuzzy neural network. The results show that the integrated rough set and deep neural network was the most accurate. The method proposed in this study could pro-vide a practical and accurate solution for building energy consumption prediction.& nbsp;
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| 18. |
- Lei, Lei, et al.
(författare)
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A dynamic anomaly detection method of building energy consumption based on data mining technology
- 2023
-
Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 263, s. 125575-
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Tidskriftsartikel (refereegranskat)abstract
- Due to the equipment failure and inappropriate operation strategy, it is often difficult to achieve energy-efficient building. Anomaly detection of building energy consumption is one of the important approaches to improve building energy-saving. The great amounts of energy consumption data collected by building energy monitoring platforms (BEMS) provides potentials in using data mining technology for anomaly detection. This study pro-poses a dynamic anomaly detection algorithm for building energy consumption data, which realizes the dynamic detection of point anomalies and collective anomalies. The algorithm integrates unsupervised clustering algo-rithm with supervised algorithm to establish a semi-supervised matching mechanism, which avoids the influence of error label and improves the efficiency of anomaly detection. A particle swarm optimization (PSO) is used to optimize the unsupervised clustering algorithm. This investigation tests the effectiveness of the proposed algo-rithm and evaluates the performance of the energy consumption clustering algorithm by using the annual electricity consumption data of an experimental building in a university. The results show that the clustering accuracy of the algorithm can reach more than 80%, and it can effectively detect the building energy con-sumption data of two different forms of outliers. It can provide reliable data support for adjusting building management strategies.
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| 19. |
- Lei, Lei, et al.
(författare)
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Displacement Identification by Computer Vision for ConditionMonitoring of Rail Vehicle Bearings
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21:6
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Tidskriftsartikel (refereegranskat)abstract
- Bearings of rail vehicles bear various dynamic forces. Any fault of the bearing seriouslythreatens running safety. For fault diagnosis, vibration and temperature measured from the bogieand acoustic signals measured from trackside are often used. However, installing additional sensingdevices on the bogie increases manufacturing cost while trackside monitoring is susceptible toambient noise. For other application, structural displacement based on computer vision is widelyapplied for deflection measurement and damage identification of bridges. This article proposesto monitor the health condition of the rail vehicle bearings by detecting the displacement of boltson the end cap of the bearing box. This study is performed based on an experimental platform ofbearing systems. The displacement is monitored by computer vision, which can image real-timedisplacement of the bolts. The health condition of bearings is reflected by the amplitude of thedetected displacement by phase correlation method which is separately studied by simulation. Toimprove the calculation rate, the computer vision only locally focuses on three bolts rather thanthe whole image. The displacement amplitudes of the bearing system in the vertical direction arederived by comparing the correlations of the image’s gray-level co-occurrence matrix (GLCM). Forverification, the measured displacement is checked against the measurement from laser displacementsensors, which shows that the displacement accuracy is 0.05 mm while improving calculation rate by68%. This study also found that the displacement of the bearing system increases with the increase inrotational speed while decreasing with static load
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| 20. |
- Lei, Lei, et al.
(författare)
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Dynamic anomaly detection of building energy consumption data
- 2023
-
Ingår i: Healthy Buildings 2023: Asia and Pacific Rim. - : International Society of Indoor Air Quality and Climate.
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Konferensbidrag (refereegranskat)abstract
- Due to the equipment failure and inappropriate operation strategy, it is often difficult to achieve energy-efficient building. Anomaly detection of building energy consumption is an important approach to improve building energy-saving. This study proposes a dynamic anomaly detection algorithm, which realizes the dynamic detection of point anomalies and collective anomalies. This investigation established a semi-supervised matching mechanism, which avoids the influence of error label and improves the efficiency of anomaly detection. A particle swarm optimization (PSO) is used to optimize the unsupervised clustering algorithm. This investigation tests the effectiveness of the proposed algorithm and evaluates the performance of the energy consumption clustering algorithm by using the annual electricity consumption data of an experimental building in a university. The results show that the clustering accuracy of the algorithm can reach more than 80%, and it can effectively detect the building energy consumption data of two different forms of outliers.
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| 21. |
- Lei, Lei, et al.
(författare)
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Inverse identification model for release rates of multiple gaseous pollution sources in an aircraft cabin
- 2023
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Ingår i: Indoor + Built Environment. - : SAGE Publications. - 1420-326X .- 1423-0070. ; 32:9, s. 1798-1810
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Tidskriftsartikel (refereegranskat)abstract
- When gaseous pollutants are airborne in an aircraft cabin, it is important to know the release rate of pollution sources efficiently and accurately for effective mitigation. At present, it is possible to locate single or multiple pollution sources using the sensor information, but there is no fast and accurate method to determine the strength of multiple pollution sources. In this study, using the monitored pollutant concentrations, with the assumption that the location of multiple pollution sources in an aircraft cabin is known, an inverse model for determining the release rates was established. In order to improve the calculation efficiency, the cause-effect matrix between the release rates of pollution sources and the concentrations of monitored points was obtained by introducing the contribution ratio of pollutant sources (CRPS) method. Due to the direct inversion of the cause-effect matrix being ill-posed, the Tikhonov regularization method was used to enhance the stability of the inverse solution. The inverse model was validated by experiment in a three-dimensional cavity with CO2 as a tracer gas. The method was further demonstrated in a three-dimensional aircraft cabin by simulated data. The results show that the inverse modelling can accurately and efficiently quantify release rates of multiple pollution sources.
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| 22. |
- Lei, Lei, et al.
(författare)
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Inverse modeling of thermal boundary conditions in commercial aircrafts based on Green's function and regularization method
- 2022
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 217
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Tidskriftsartikel (refereegranskat)abstract
- To quantify the thermal environment in a commercial aircraft, the accurate estimation of the thermal boundary conditions is very critical. However, there is no fast and accurate method. In this study, an inverse modeling using Computational Fluid Dynamics (CFD) combined with Green's function and regularization method is proposed to identify the convective heat transfer of inner wall by using the air temperature at monitored points in the cabin. Green's transfer matrix is used to describe the causal relationship between the monitored air temperatures and the thermal boundary conditions, which greatly improves the calculation efficiency. Due to the illposed nature of the inverse problem, regularization methods are used to ensure the stability of the inversion solution. This investigation compares the performance of Tikhonov, truncated singular value decomposition (TSVD) and damped generalized singular value decomposition (DGSVD). To verify the feasibility of the inverse modeling, the inner wall convective heat transfer of the cabin is solved by using the measured and simulated data in a small-scale cabin testbed and a full-scale aircraft cabin, respectively. The results show that the proposed inverse modeling can accurately and effectively determine the convective heat transfer on the inner wall.
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| 23. |
- Lei, Lei, et al.
(författare)
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Predictive control of multi-zone variable air volume air-conditioning system based on radial basis function neural network
- 2022
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Ingår i: Energy and Buildings. - : Elsevier BV. - 0378-7788 .- 1872-6178. ; 261, s. 111944-
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Tidskriftsartikel (refereegranskat)abstract
- The multi-zone variable air volume (VAV) air-conditioning system is a complex thermal system with large delay and nonlinearity. Due to the complex environment of multi-zone buildings and the complicated operation process of the VAV air-conditioning system, there are many difficulties in the room temperature control. This paper firstly establishes a multi-zone building model for room temperature using resistance-capacitance method. This investigation simulates and measures the dynamic response of room temperature in a three-floor building without/with air-conditioning for validation. Then a multizone VAV air-conditioning system room temperature predictive control model based on radial basis function (RBF) neural network (NN) is proposed. This study sets up a multi-zone VAV air-conditioning system experimental platform in the three rooms on the first floor of the building and implements the predictive control model based on the RBF neural network. The experimental results show that the predictive control model based on RBF NN is able to meet room temperature requirements. It also has strong antiinterference performance and ensures stable static pressure of the main air supply duct. The multizone building model can accurately simulate the temperature changes of each room when the air supply volume varies.
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| 24. |
- Lei, Yumeng, et al.
(författare)
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Choice Behavior and Diffusion Impact Analysis of Connected and Autonomous Vehicles Travelers with Managed Lanes
- 2024
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Konferensbidrag (refereegranskat)abstract
- With the accelerated integration of connected and autonomous vehicle (CAV) into transportation system, CAV has evolved rapidly. Emerging studies have focused onthe factors that influence travelers’ acceptance of CAV, the measures that contribute to CAV travel choice intention, and the methods that facilitate CAV promotion. However,different incentives in the CAV diffusion effect, and the trend of CAV travelers diffusion are the key questions that still remains to be investigated. Therefore, this study establishes a structural equation model (SEM) framework to explore the impact of external environmental factors and internal subjective factors on travel mode choice. Based on the identified influencing factors of the SEM, this study develops an agent based model (ABM) simulation approach to examine the diffusion trend of CAV travelers from an individual perspective. To calibrate the model, a questionnaire survey is designed to obtain data on the characteristics of travelers in Shenzhen, Guangdong Province, China, followed by a quantitative impact analysis. The survey results show that the CAV choice intention is influenced by individual and travel characteristics, as well as individual innovativeness and social influence utility of the social network in which the traveler is involved. The simulation experiments revealed that the diffusion ofCAV travelers is a complex process involving interactions among policymakers, CAV operators, and travelers. A lower CAV travel cost has a positive impact on the primary and middle process of CAV travelers diffusion. The findings contribute to understanding travelers’ demands and to helping agencies and CAV operators to implement effective promotion strategies.
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| 25. |
- Lyo, A-Ran, et al.
(författare)
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The JCMT BISTRO Survey: An 850/450 mu m Polarization Study of NGC 2071IR in Orion B
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 918:2
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of simultaneous 450 mu m and 850 mu m polarization observations toward the massive star-forming region NGC 2071IR, a target of the BISTRO (B-fields in STar-forming Region Observations) Survey, using the POL-2 polarimeter and SCUBA-2 camera mounted on the James Clerk Maxwell Telescope. We find a pinched magnetic field morphology in the central dense core region, which could be due to a rotating toroidal disklike structure and a bipolar outflow originating from the central young stellar object IRS 3. Using the modified Davis-Chandrasekhar-Fermi method, we obtain a plane-of-sky magnetic field strength of 563 +/- 421 mu G in the central similar to 0.12 pc region from 850 mu m polarization data. The corresponding magnetic energy density of 2.04 x 10(-8) erg cm(-3) is comparable to the turbulent and gravitational energy densities in the region. We find that the magnetic field direction is very well aligned with the whole of the IRS 3 bipolar outflow structure. We find that the median value of polarization fractions is 3.0% at 450 mu m in the central 3 ' region, which is larger than the median value of 1.2% at 850 mu m. The trend could be due to the better alignment of warmer dust in the strong radiation environment. We also find that polarization fractions decrease with intensity at both wavelengths, with slopes, determined by fitting a Rician noise model of 0.59 +/- 0.03 at 450 mu m and 0.36 +/- 0.04 at 850 mu m, respectively. We think that the shallow slope at 850 mu m is due to grain alignment at the center being assisted by strong radiation from the central young stellar objects.
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