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91.
Hung-Hsia Chen R. Anbarasan Long-Sheng Kuo Ping-Hei Chen 《Journal of Materials Science》2011,46(6):1796-1805
ε-Caprolactone (CL) was subjected to ring opening polymerization (ROP) under inert (nitrogen) atmosphere at 413 K for 1 h in the presence of stannous octoate (SO) as a catalyst and Eosin Y, a xanthenes type dye as a novel chemical initiator. The ROP was carried out at two different experimental conditions, namely at various concentrations of initiator and monomer, to get more scientific information from the resultant product. Thus, obtained Eosin Y conjugated poly(ε-caprolactone) (PCL) was characterized by different analytical tools like FTIR spectroscopy, NMR spectroscopy, gel permeation chromatography (GPC), UV–Visible spectroscopy, photoluminescence (PL) spectroscopy, X-ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). Finally, the morphology of the Eosin Y conjugated PCL was studied by scanning electron microscopy (SEM). The binding constant (K) was determined from both UV–Visible spectroscopy and PL spectroscopy, and the static quenching mechanism was proposed. The number of binding site (n) was also determined from PL spectroscopy and the results were compared with the FTIR-RI method. 相似文献
92.
Planar Heterojunction Perovskite Solar Cells Incorporating Metal–Organic Framework Nanocrystals 下载免费PDF全文
93.
Toward multiple maximum power point estimation of photovoltaic systems based on semiconductor theory
Jen‐Cheng Wang Yu‐Li Su Kun‐Chang Kuo Jyh‐Cherng Shieh Joe‐Air Jiang 《Progress in Photovoltaics: Research and Applications》2015,23(7):847-861
Environmental conditions, such as temperature, non‐uniform irradiation, and solar shading, deeply affect the characteristics of photovoltaic (PV) modules in PV‐assisted generation systems. Several local maximum power points (MPPs) are found in the power–voltage curve of PV systems constructed by series/parallel‐connected PV modules under partially shaded conditions. The characteristics of PV systems change unpredictably when multiple MPPs occur, so the actual MPP tracking (MPPT) becomes a difficult task. Conventional MPPT methods for the PV systems under partially shaded conditions cannot quickly find the actual MPP such that the optimal utilization of PV systems cannot be achieved. Based on the p–n junction semiconductor theory, we develop a multipoint direct‐estimation (MPDE) method to directly estimate the multiple MPPs of the PV systems under partially shaded conditions and to cope with the mentioned difficulties. Using the proposed MPDE method, the multiple MPPs of the PV systems under partially shaded conditions can be directly determined from their irradiated current–voltage and power–voltage characteristic curves. The performances of the proposed MPDE method are evaluated by examining the characteristics of multiple MPPs of PV systems with respect to different shading strengths and numbers of the shaded PV modules and also tested using the field data. The experimental results demonstrate that the proposed MPDE method can simply and accurately estimate the multiple MPPs of the PV systems under partially shaded conditions. The optimization of MPP control models and the MPPT for PV systems could be achieved promisingly by applying the proposed method. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
94.
Two types of problems associated with time-optimal control of multiple manipulators moving a commonly held object along specified trajectories are studied. The first problem involves finding the minimum traveling time and the optimal control torques for any desired motion programs of the given trajectory. The second problem involves finding the optimal velocity distribution along the trajectory such that the motion can be completed in the minimum time. To solve these problems, a parametric form of the generalized dynamic equation is derived. An iterative search procedure is developed for solving the first problem. During the search, the lower bound of the traveling time at any point of the given trajectory is determined by using the linear programming technique. The second problem is solved by integrating the parametric dynamic equation along the given trajectory based on the phase-plane switching curve approach. The maximum acceleration and the upper bound of the operation speed at each integration instance are determined from two linear programs. The proposed methods are applicable to various complex multi-robot systems and can handle nonlinear torque-speed characteristics of the joint actuators. © 1996 John Wiley & Sons, Inc. 相似文献
95.
Mohamed Gamal Mohamed Maha Mohamed Samy Tharwat Hassan Mansoure Chia-Jung Li Wen-Cheng Li Jung-Hui Chen Kan Zhang Shiao-Wei Kuo 《International journal of molecular sciences》2022,23(1)
There is currently a pursuit of synthetic approaches for designing porous carbon materials with selective CO2 capture and/or excellent energy storage performance that significantly impacts the environment and the sustainable development of circular economy. In this study we prepared a new bio-based benzoxazine (AP-BZ) in high yield through Mannich condensation of apigenin, a naturally occurring phenol, with 4-bromoaniline and paraformaldehyde. We then prepared a PA-BZ porous organic polymer (POP) through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) in the presence of Pd(PPh3)4. In situ Fourier transform infrared spectroscopy and differential scanning calorimetry revealed details of the thermal polymerization of the oxazine rings in the AP-BZ monomer and in the PA-BZ POP. Next, we prepared a microporous carbon/metal composite (PCMC) in three steps: Sonogashira coupling of AP-BZ with P-T in the presence of a zeolitic imidazolate framework (ZIF-67) as a directing hard template, affording a PA-BZ POP/ZIF-67 composite; etching in acetic acid; and pyrolysis of the resulting PA-BZ POP/metal composite at 500 °C. Powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller (BET) measurements revealed the properties of the as-prepared PCMC. The PCMC material exhibited outstanding thermal stability (Td10 = 660 °C and char yield = 75 wt%), a high BET surface area (1110 m2 g–1), high CO2 adsorption (5.40 mmol g–1 at 273 K), excellent capacitance (735 F g–1), and a capacitance retention of up to 95% after 2000 galvanostatic charge–discharge (GCD) cycles; these characteristics were excellent when compared with those of the corresponding microporous carbon (MPC) prepared through pyrolysis of the PA-BZ POP precursors with a ZIF-67 template at 500 °C. 相似文献
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98.
地表蒸散发(ET)是水循环和能量循环的关键组成部分,具有极其重要的应用价值。研究旨在发展一种可靠且高效的深度神经网络(DNN)模型,基于MODIS可见光数据、微波AMSR2亮度温度和数字高程DEM,实现全天候全球高分辨率每日ET的估算。利用FLUXNET和AmeriFlux通量网6种代表性土地覆盖类型的148个站点观测数据来训练和验证DNN模型,结果表明:DNN模型可以有效建立卫星数据(MODIS、AMSR2数据)与ET之间的关系;6种地类的ET估算结果验证的平均绝对误差(MAE)为0.16—0.63 mm/d,均方根误差(RMSE)为0.27—0.89 mm/d,除裸地的决定系数(R2)为0.37以外,其他地类的R2均>0.7。通过对比模型估算的ET与MOD16A2和GLEAM的ET产品,结果表明3种产品的ET空间分布特征相似,ET值非常接近,估算得到的全球2020年日均ET为0—4 mm/d。 相似文献
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100.
Most of the rivers in Taiwan are short and run on a steep slope due to the island's topography. Because of the weak correlations of streamflow in time and the occurrence of extreme events such as typhoons, classical autoregressive-moving average (ARMA) models have difficulties in forecasting and synthesizing the average 10-day streamflow in Taiwan. In this study, the synthesis of the average 10-day streamflow of the Tanshui River in Taiwan is accomplished by a section model. The model divides the year-round streamflow records into several sections according to their distinguishable patterns, and each section is modeled by a separate ARMA model. For parameter control, a heuristic grouping procedure, based on statistical inference of the random noise part, is used to separate a year into a minimum number of sections. The section separation procedure follows the general precipitation pattern in a year. The case study results indicate high statistical agreement between synthesized series and historical records. Additionally, a new procedure, extended autocorrelation function (EACF), is introduced and applied in this study to assist in model identification. 相似文献