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1.
为进一步提高城市生态监测的精确度,在前人开展的城市生态遥感监测研究的基础上引入“区域尺度”的概念,充分考虑小区域范围内不同地物间的交互作用,并利用移动窗口模型(Moving Window-Remote Sensing Ecology Index, MW-RSEI)对沈阳市浑南区的遥感影像进行逐像元分析。实验结果表明,MW-RSEI模型和生态遥感监测模型(Remote Sensing Ecology Index, RSEI)在整体生态评价趋势上表现出一致性。但MW-RSEI模型对城市生态中的细节区域表征更明显。考虑到建筑及裸地周围植被的影响,其较差生态区域的占比仅为6%,生态评价为优的区域占比为11%。研究区生态评价结果表现得较为连续,并未出现明显的断层现象。该结果具有现实意义且与实际生态分布更为符合。MW-RSEI模型在城市生态监测中更为适用,可为相关部门提供一定的技术参考。 相似文献
2.
《Ceramics International》2021,47(20):28557-28565
To reduce the energy consumption of cooling in the hot summer days, searching for novel NIR shielding materials for buildings is of great value. In this report, monodispersed F doped TiO2 nanocrystals with an average size of 8.6 nm were synthesized as novel solar shielding materials for energy-saving windows. All the products adopted an anatase TiO2 structure. After doping of F ions, the morphology of TiO2 was transformed from an irregular shape to a pseudospherical shape. The Raman shift and XPS depth analysis confirmed the successful doping of F− ions into the lattice oxygen sites in the TiO2 structure. The introduction of F− ions generated free electrons and bulk Ti3+ in TiO2 crystals, which activated a localized surface plasmon resonance (LSPR) absorption in the NIR region. Correspondingly, the NIR shielding performance of the TiO2 films improved with increasing F doping amounts. The NIR shielding value of the films increased from 1.3% to 43.2% when the molar ratio of F to Ti increased from 0 to 0.3. The reason can be attributed to the enhanced NIR absorption induced by the increased electron concentration after doping of fluorine ions. The F–TiO2 films showed superior visible transmittance (90.1–96.7%). Moreover, the F–TiO2 films lowered the indoor temperature of the heat box by 5.3 °C in the thermal tests. Overall, the prepared F–TiO2 nanocrystals show a great potential to be used for energy-saving windows. 相似文献
3.
标准LoRaWAN协议中定义的纯ALOHA信道接入方法在网络负载较大时会造成大量碰撞,使LoRa网络的可扩展性和可靠性受到极大挑战。为此提出了一种将先听后说与模拟退火相结合(Listen Before Talk combined with Simulated Annealing,LBT-SA)的LoRa信道接入方法。该方法通过在设备发送之前先监听信道,降低信道被同时接入的概率,并以成功传输所需退避时间为初始值,搜索更小的退避时间。仿真结果表明,LBT-SA和基于二元指数退避算法的先听后说(Listen Before Talk,LBT)方法在包成功传输率方面保持了高度的一致,并且LBT-SA在周期传输过程中逐渐减少了不必要的退避时间,从而减少了时延。在多达10 000个终端接入单个网关的场景中,该算法的平均退避时间至少降低了16.38%。 相似文献
4.
Li Chuan-Kang Zhang Hong-Xin Liu Jia-Xin Zhang Yuan-Qing Zou Shan-Chen Fang Yu-Tong 《计算机科学技术学报》2020,35(4):900-912
Journal of Computer Science and Technology - Window detection is a key component in many graphics and vision applications related to 3D city modeling and scene visualization. We present a novel... 相似文献
5.
页岩油和致密油是中国目前油气勘探的热点,页岩生烃模拟实验可为此类油气资源勘探提供重要数据。以鄂尔多斯盆地延长组7段(长7段)页岩为例,利用金管-高压釜模拟生烃装置,系统研究了Ⅱ型有机质在与"生油窗"对应的成熟度范围(Easy Ro 0.7%~1.6%)内生烃产物中的气体烃(C1-5)、轻烃(C6-14)、重烃(C14+)、各族组分,以及生烃残渣的地球化学特征。发现长7段页岩在生油期可同时生成2.35~103.91 mL/g的气体烃和10.83~88.24 mg/g的轻烃。重烃的生成高峰对应的Easy Ro约为1.0%,与其中的饱和烃、芳烃和非烃的高峰产率对应的成熟度非常接近。重烃中沥青质的产率在Easy Ro约1.35%后开始下降,说明沥青质在此后才开始大量裂解与固化。而对原油物性影响很大的轻重比[(气体烃+轻烃)/重烃]及气油比[气体烃/(轻烃+重烃)]随成熟度增加而不断增大,其增速分别在Easy Ro为1.05%~1.15%之后明显变快。在生油过程中,长7段页岩残渣HI值和H元素的大量减少、干酪根固体碳同位素的变重均发生在Easy Ro约1.00%之前。干酪根碳同位素的变化相对较小,在鄂尔多斯盆地可以作为母源指标。通过对生烃产物中6种常见生物标志物成熟度参数的对比,证实多环芳烃成熟度参数中的甲基菲指数(MPI)和甲基菲比值(F1)在整个生油窗内都与成熟度有很好的线性相关性,可用于鄂尔多斯盆地母源为长7段页岩的原油成熟度判识。生烃产物的各地球化学特征变化节点、以及成熟度指标可用于鄂尔多斯盆地长7段页岩油或相关致密油资源的可采性评价。 相似文献
6.
In this work, gallium doped copper sulfide (Ga-doped CuS) nanocrystals were prepared using a solvothermal method. The effects of Ga doping on the crystal structures, chemical composition, morphology, optical properties and thermal performance of copper sulfide (CuS) were investigated. The Ga-doped CuS nanocrystals had a hexagonal structure comparable to that of pure CuS. The Cu+/Cu2+ ratio first decreased and then increased with increasing Ga3+ doping. Both CuS and Ga-doped CuS exhibited nanoplate and nanorod morphologies. The visible transmittance of the Ga-doped CuS films was in the range of 61–77.1%. Importantly, the near-infrared (NIR) shielding performance of the films can be tuned by adjusting the concentration of the Ga dopant. The NIR shielding value of the optimal Ga-doped CuS film was 72.4%, which was approximately 1.5 times as high as that of the pure CuS film. This can be ascribed to the enhanced plasmonic NIR absorption that resulted from an increase in the hole concentration after doping with Ga3+ ions. In the thermal performance test, the Ga-doped CuS film lowered the interior temperature of the heat box by 9.1 °C. Therefore, the integration of good visible transmittance and high NIR shielding performance make the Ga-doped CuS nanocrystals a promising candidate for energy-efficient window coatings. 相似文献
7.
Window opening and closing is the most preferred behavior for occupants to control their indoor environment in homes. This study aims to identify driving forces for window opening and closing behavior in the home. The additional field survey was carried out for the cooling period after following the previous study. The state of windows and environmental variables for outdoor and indoor were continuously monitored in 23 sample homes over one year. The monitored data provide evidence that there is a statistically significant relationship between window opening behavior and outdoor temperature. The behavior of the occupant's manual control of windows can be described by seasonal effects, occupancy, and time of day. Indoor stimuli, such as such as temperature, humidity, and CO2, can better account for the window opening behavior than can outdoor stimuli. There are clear differences in driving variables between window opening and closing behavior. The closing behavior is better described when the outdoor and indoor variables are combined. Finally, multivariate logistic regression models were developed to predict typical patterns of window opening and closing as a function of indoor and outdoor variables. 相似文献
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9.
合成流量法对下游站流量作出预报的关键是确定各上游站流量到达下游站的时间。在实际中常采用平均传播时间,然而不同水情下真实传播时间与平均传播时间存在一定的差距,影响预报精度。对此,提出时间窗口概念,以平均传播时间为中心,向前、后各开一个时间窗口,用上游各站时间窗口内流量的线性组合表示其到达下游站的流量,以提高模型对不同水情的适应能力和预报精度。以三峡水库2009~2015年流量数据率定参数,以2016~2018年流量数据作为预报对象,试验结果表明时间窗口法能够显著改善预报精度。 相似文献
10.