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Now showing items 1 - 16 of 128

  • Urban water capacity: Irrigation for heat mitigation

    Wang, Chenghao   Wang, Zhi-Hua   Yang, Jiachuan  

    Our world has been continuously urbanized and is currently accommodating more than half of the human population. Despite that cities cover only < 3% of the Earth's land surface area, they emerged as focal points of human activities, and confront numerous environmental challenges as a result of changes in landscapes, hydroclimate, ecosystems, and biodiversity. In particular, the built environment usually experiences exacerbated heat stress induced by global climate and landscape changes, commonly known as the urban heat island effect. Urban irrigation, as a climate adaptation and mitigation strategy, is effective in cooling the built environment, but exhibits large uncertainties in the trade-off between water use and heat mitigation capacity. Here we show the efficiency of cooling effect induced by irrigation of urban vegetation, represented by a novel metric, viz. urban water capacity, analogous to the heat capacity, across the contiguous United States (CONUS) during summertime via numerical simulations. The urban water capacity is calculated as the average irrigation depth per degree of urban temperature reduction; the values are 4.52 +/- 0.77 mm day(-1) degrees C-1 and 7.27 +/- 1.27 mm day(-1) degrees C-1 (mean +/- standard deviation) for surface and near-surface air cooling, respectively, over the CONUS. The robustness of urban water capacity is further exemplified in an extreme heat wave event, during which the warming anomaly is partially offset by the additional cooling from urban irrigation. Estimates of water capacity provide a quantitative metric for evaluating the efficacy of irrigation in urban planning under current heat stress and future warming.
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  • A New Quantum Blind Signature Scheme with BB84-State

    Chen, Feng-Lin   Wang, Zhi-Hua   Hu, Yong-Mo  

    The blind signature is widely used in cryptography applications because it can prevent the signer from gaining the original message. Owing to the unconditional security, the quantum blind signature is more advantageous than the classical one. In this paper, we propose a new provable secure quantum blind signature scheme with the nonorthogonal single-photon BB84-state and provide a new method to encode classical messages into quantum signature states. The message owner injects a randomizing factor into the original message and then strips the blind factor from the quantum blind signature signed by the blind signer. The verifier can validate the quantum signature and announce it publicly. At last, the analytical results show that the proposed scheme satisfies all of the security requirements of the blind signature: blindness, unforgeability, non-repudiation, unlinkability, and traceability. Due to there being no use of quantum entanglement states, the total feasibility and practicability of the scheme are obviously better than the previous ones.
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  • Period investigation of Algol systems TZ Eri and TU Her

    Wang, Zhi-Hua   Zhu, Li-Ping   Li, Lin-Jia   Tian, Xiao-Man  

    TZ Eri and TU Her are both classic Algol-type systems (Algols). By observing and collecting times of minimum light, we constructed the O - C curves for the two systems. The long-time upward and downward parabolas shown in these diagrams are considered to be the result of the combination of mass transfer and angular momentum loss. The secular orbital period change rates are dP/dt =3D 4.74(+/- 0.12) x 10(-7) d yr(-1) and dP/dt =3D -2.33(+/- 0.01) x 10(-6) d yr(-1), respectively. There are also cyclic variations in their O - C curves which might be caused by the light-travel time effect (LTTE). A circumbinary star may exist in the TZ Eri system with a mass of at least 1.34 M-circle dot,M- while there are possibly two celestial bodies that almost follow a 2 : 1 resonance orbit around the TU Her binary pair. Their masses are at least 2.43 M-circle dot and 1.27 M-circle dot.
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  • A New Quantum Blind Signature Scheme with BB84-State

    Chen, Feng-Lin   Wang, Zhi-Hua   Hu, Yong-Mo  

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  • Thermodynamic characterisation of urban nocturnal cooling

    Wang, Zhi-Hua   Li, Qi  

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  • A Backward-Lagrangian-Stochastic Footprint Model for the Urban Environment

    Wang, Chenghao   Wang, Zhi-Hua   Yang, Jiachuan   Li, Qi  

    Built terrains, with their complexity in morphology, high heterogeneity, and anthropogenic impact, impose substantial challenges in Earth-system modelling. In particular, estimation of the source areas and footprints of atmospheric measurements in cities requires realistic representation of the landscape characteristics and flow physics in urban areas, but has hitherto been heavily reliant on large-eddy simulations. In this study, we developed physical parametrization schemes for estimating urban footprints based on the backward-Lagrangian-stochastic algorithm, with the built environment represented by street canyons. The vertical profile of mean streamwise velocity is parametrized for the urban canopy and boundary layer. Flux footprints estimated by the proposed model show reasonable agreement with analytical predictions over flat surfaces without roughness elements, and with experimental observations over sparse plant canopies. Furthermore, comparisons of canyon flow and turbulence profiles and the subsequent footprints were made between the proposed model and large-eddy simulation data. The results suggest that the parametrized canyon wind and turbulence statistics, based on the simple similarity theory used, need to be further improved to yield more realistic urban footprint modelling.
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  • Pore Characteristics and Slurryability of Coal Blends

    Zhu, Jie-Feng   Wang, Jie   Liu, Jian-Zhong   Cheng, Jun   Wang, Zhi-Hua   Zhou, Jun-Hu   Cen, Ke-Fa  

    The pore characteristics and slurryability of two coal blends between Shigang anthracite coal and Huangling bituminous coal (SG/HL), and Guizhou anthracite coal and Xiaotun lean coal (GZ/XT), respectively, were investigated. The fractal dimensions of coal were calculated in the two regions of P/P-0 < 0.45 and P/P-0 > 0.45 and defined as D, and D-2, respectively. Upon an increase in the blending ratio of parent coal with smaller BET surface area (SBET) and total pore volume (TPV), the S-BET and TPV of coal blends monotonously decreased. D-1 was mainly related to the Smeso/macro(10-220 nm)/S-total and mineral phase within coal while D-2 was closely affected by the Vmeso(2-10 nm)/V-total. D-1 of SG/HL coal blends had no apparent linear correlation with the pore structure parameters whereas I), of GZ/XT coal blends changed linearly with the pore structure parameters. Both D-2 of SG/HL coal blends and that of GZ/XT coal blends changed linearly with the pore structure parameters. The slurry quality of coal water slurry (CWS) prepared from coal blends is comprehensively affected by the physicochemical properties and blending ratio of parent coals. Therefore, the maximum solid loading (MSL) and water separation ratio (WSR) of CWS prepared from coal blends do not always change linearly with the blending ratio of parent coal.
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  • Diagnostic accuracy of pediatric atypical appendicitis: Three case reports.

    Wang, Zhi-Hua   Ye, Jing   Wang, Yu-Shui   Liu, Yan  

    RATIONALE: Acute appendicitis is one of the most common causes of acute abdomen in children, yet it is difficult to diagnose in young children because its clinical manifestations may be atypical. Here, 3 atypical clinical cases associated with appendicitis in children are reported.; PATIENT CONCERN: The 1st case corresponds to a 5-year-old male patient who presented with abdominal discomfort, intermittent fevers, and vomiting, have increased white blood cell (WBC) count and C-reactive protein (CRP). The second case is a 7-year-old male patient who began with intermittent fevers and lower quadrant abdominal pain, showing increased WBC count and CRP. The 3rd case corresponds to a 7-year-old female patient who presented with intermittent fevers, abdominal pain, and forebreast discomfort, demonstrating increased WBC count and CRP.; DIAGNOSES: Abdominal computed tomography (CT) scan presented data suggestive of enlarged appendix in diameter, and stercolith, corroborated through surgery.; INTERVENTION: Two patients were treated by appendectomy, and 1 patient was treated conservatively with antibiotics.; OUTCOMES: Three patients were treated successfully. At 3-month follow-up, the patients had no complaints of discomfort with no relapse of appendicitis.; LESSONS: Due to atypical symptoms of children, the diagnosis of appendicitis is often delayed, suggesting that the clinicians should be aware of this disease when encountering gastroenteritis patients with elevated WBC and CRP. Furthermore, abdominal CT scan should be taken into consideration when patients showed high level of WBC and CRP, whose appendix is not seen on ultrasound.=20
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  • Photometric investigation of the eclipsing binary TX Herculis observed by LUT

    Zhu, Li-Ying   Tian, Xiao-Man   Zhou, Xiao   Li, Lin-Jia   Wang, Zhi-Hua  

    The lander of China's Chang'E-3 spacecraft is equipped with a 15-cm telescope that is very useful for monitoring celestial objects in the ultraviolet (UV) band (245-340nm). The Lunar-based Ultraviolet Telescope (LUT) is the first long-term lunar-based astronomical observatory, that can make uninterrupted observations of a target from the Moon. Here we present the continuous complete UV light curve of the eclipsing binary TX Herculis (TX Her). The analysis of the light curve suggests that TX Her is a detached binary. The dip in the light curve was explained by the emergence of a stellar dark spot on the less massive F0 type component. The cyclic change of arrival eclipse times for the system reveals that it contains an additional stellar companion with a minimal mass of 0.35 M-circle dot and a period of 48.92 yr, which is supported by the detected light contribution of the third body from light curve analysis. This third body may play an important role in the formation of the present short-period system TX Her.
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  • Manipulating Nanowire Assembly for Flexible Transparent Electrodes

    Liu, Jian-Wei   Wang, Jin-Long   Wang, Zhi-Hua   Huang, Wei-Ran   Yu, Shu-Hong  

    Manipulating nanowire assembly could help the design of hierarchical structures with unique functionalities. Herein, we first report a facile solution-based process under ambient conditions for co-assembling two kinds of nanowires which have suitable composition and functionalities, such as Ag and Te nanowires, for the fabrication of flexible transparent electrodes. Then Te nanowires can be etched away easily, leaving Ag nanowire networks with controllable pitch. By manipulating the assembly of Ag and Te nanowires, we can precisely tailor and balance the optical transmittance and the conductivity of the resulting flexible transparent electrodes. The network of Ag nanowires which have tunable pitch forms a flexible transparent conducting electrode with an averaged transmission of up to 97.3% and sheet resistances as low as 2.7 W/sq under optimized conditions. The work provides a new way for tailoring the properties of nanowire-based devices.
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  • Upregulated dynamin 1 in an acute seizure model and in epileptic patients.

    Li, Ying-Ying   Chen, Xiao-Ni   Fan, Xin-Xin   Zhang, Yu-Jiao   Gu, Juan   Fu, Xin-Wei   Wang, Zhi-Hua   Wang, Xue-Feng   Xiao, Zheng  

    Dynamin 1 is a neuron-specific guanosine triphosphatase (GTPase) that is an essential component of membrane fission during synaptic vesicle recycling and endocytosis. This study evaluated the dynamin 1 expression pattern in the acute lithium-pilocarpine rat model and in patients with temporal lobe epilepsy (TLE) and investigated whether altering the dynamin 1 expression pattern affects epileptic seizures in vivo and in vitro. The immunofluorescence, western blot analysis, and reverse transcription-PCR results show that the dynamin 1 expression level increased significantly in experimental rats from day 1 to day 7 after the onset of seizures and was significantly higher in TLE patients. The behavioral study revealed that inhibiting dynamin 1 increased the latency time of the first seizure and decreased the frequency and severity of the seizures. In addition, electrophysiological recordings from brain slices showed that inhibiting dynamin 1 reduces the frequency of Mg-free induced seizure-like activity. The anticonvulsant effect of dynasore was more effective at 10 M than at 1 M or 160 M. These results indicate that the altered level of dynamin 1 may contribute to the development of epileptic seizures and that the targeted regulation of dynamin 1 activity may control epileptic seizures. =C2=A9 2014 Wiley Periodicals, Inc.
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  • In Situ Seed-Mediated High-Yield Synthesis of Copper Nanowires on Large Scale

    Fu, Qi-Qi   Li, Yu-Da   Li, Hui-Hui   Xu, Liang   Wang, Zhi-Hua   Yu, Shu-Hong  

    Copper nanowires (Cu NWs) are among ideal candidates for fabricating various advanced nanodevices, especially flexible electronics and transparent conductive electrodes. However, although many efforts have been made, the commercialization of Cu NVVs is still difficult. Herein, we report an in situ seed -mediated two-step strategy to synthesize well-defined Cu NWs in high yield. In the first step, that is, seed formation process, most Cu ions (85%) in situ transform to nondecahedral Cu nanodots (NDs). These Cu NDs can promote the formation of decahedral multiply twinned particles (DMTPs) and the subsequent growth of Cu NWs by selectively inhibiting the spontaneous ripening of nanoparticle (NP) byproducts in the second step. The amount and quality of Cu NDs play an important role in high-yield production of Cu NWs, and the yield was successfully increased to 2.4 times higher than that of the conventional methods. Furthermore, an effective shaking-rotating purification technique was developed to fully separate Cu NWs from the final product solution. After scaling up the reaction, 50 g of high-quality Cu NWs can be produced with a uniform size and high aspect ratio at a very low material cost of $ 0.99/g. These promising results not only provide a high-yield and low-cost synthetic route but also can promote the widespread commercialization of Cu NWs in advanced nanodevices.
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  • Large-eddy simulation of the impact of urban trees on momentum and heat fluxes

    Li, Qi   Wang, Zhi-Hua  

    Trees in urban environment have a profound impact on the microclimate and environmental sustainability. Realistically representing them in urban models is an ongoing area of research in urban environmental study. In this paper, we develop a novel large-eddy simulation (LES) model (LES-UrbanTree) that resolves the buildings and parameterizes urban trees by accounting for their aerodynamic impact. The shading effect of trees is explicitly taken into account in LES-UrbanTree by a subsurface conduction model coupled to LES. Two-dimensional street canyons with trees in the middle of the street are used as a prototype for case studies. It is found that under moderate canyon aspect ratio (i.e. height/width being 0.5 and 1), trees taller than the mean building height leads to the strongest modification of the flow and temperature fields. Tall trees strongly impact the downward transport of high momentum (i.e. sweeping events) and therefore alter the momentum and heat fluxes most significantly through direct interaction with the strong shear layer near the roof top. Simulations of street canyons of different aspect ratios also produce physically consistent results, thus demonstrating the application potential of LES-UrbanTree. The study overall highlights the importance of representing both the aerodynamic and thermodynamic changes due to trees in urban models.
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  • Diurnal changes in urban boundary layer environment induced by urban greening

    Song, Jiyun   Wang, Zhi-Hua  

    Urban green infrastructure has been widely used for mitigating adverse environmental problems as well as enhancing urban sustainability of cities worldwide. Here we develop an integrated urban-land-atmosphere modeling framework with the land surface processes parameterized by an advanced urban canopy model and the atmospheric processes parameterized by a single column model. The model is then applied to simulate a variety of forms of green infrastructure, including urban lawns, shade trees, green and cool roofs, and their impact on environmental changes in the total urban boundary layer (UBL) for a stereotypical desert city, viz. Phoenix, Arizona. It was found that green roofs have a relatively uniform cooling effect proportional to their areal coverage. In particular, a reduction of UBL temperature of 0.3 degrees C and 0.2 degrees C per 10% increase of green roof coverage was observed at daytime and nighttime, respectively. In contrast, the effect of greening of street canyons is constrained by the overall abundance of green infrastructure and the energy available for evapotranspiration. In addition, the increase in urban greening causes boundary-layer height to decrease during daytime but increase at nighttime, leading to different trends of changes in urban air quality throughout a diurnal cycle.
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  • Phase diagram of Sm-Nd-Fe ternary system

    Wang, Bo-wen   Huang, Wen-mei   Ji, Zhi-chao   Wang, Zhi-hua   Sun, Ying   Weng, Ling  

    Phase equilibria of the Sm-Nd-Fe ternary system were determined in an isothermal section of 500 degrees C and vertical sections of SmFe2-NdFe2 and (Sm0.86Nd0.12)Fe-x (1.6 <= x <= 2.4) by optical microscopy, X-ray diffraction analysis, electron probe. microanalysis (EPMA), and differential thermal analysis (DTA) techniques. There are four intermetallic phases: (Sm,Nd)Fe-2, (Sm,Nd)Fe-3, (Sm,Nd)(5)Fe-17 and (Sm,Nd)(2)Fe-17 in the Sm Nd Fe ternary system, and no (Sm,Nd)(6)Fe-23 phase exists in this system. The isothermal section of 500 degrees C possesses 7 single-phase regions, 8 two-phase regions, and 4 three-phase regions. The vertical section of SmFe2-NdFe2 contains 2 single-phase regions, 4 two-phase regions, and 7 three-phase regions, and that of (Sm0.88Nd0.12)Fe-x consists of 2 single-phase regions, 5 two-phase regions, and 2 three-phase regions. The peritectic temperatures for (Sm1-xNdx)Fe-2 alloys decrease with increasing the Nd content when x <= 0.5, and the substitution of Nd for Sm makes the stability of (Sm,Nd)Fe-2 phase decrease.
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  • Diurnal changes in urban boundary layer environment induced by urban greening

    Song, Jiyun   Wang, Zhi-Hua  

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