共查询到20条相似文献,搜索用时 15 毫秒
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采用双重分布函数的格子玻尔兹曼模型,对单脉冲激光金属打孔过程中的快速相变传热进行研究.模型考虑了金属材料熔化后熔体的流动换热,并采用浸没移动边界方案对过程中的固液界面进行追踪.采用纯导热模型和考虑对流的换热模型计算,将结果和试验进行对比,结果表明:在激光打孔过程中熔体的流动对相变传热产生较大影响,采用考虑流动换热模型的结果与实验更接近.进而对熔化速度、熔化深度以及温度场的变化进行分析,并探讨不同激光工艺参数对相变过程的影响.模拟发现一个脉冲结束后,激光的脉宽越大,孔深越小,孔径越大,且最高温度较短脉冲激光越低. 相似文献
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离心粒化方法在高温熔渣余热回收方面具有结构紧凑、能耗低、得到的渣粒粒径小等优势。但受到粒化仓空间限制,会出现高温熔融渣粒碰撞、黏附在壁面的现象,影响装置运行的稳定性。本文针对该问题建立了熔融渣粒碰撞壁面的三维对称模型,结合VOF(流体体积)方法和凝固/融化模型来模拟熔渣动态形变和凝固换热过程。模拟得到,两个同粒径熔融渣粒在壁面上相继沉积会出现碰撞、铺展、回缩、飞溅、稳定的动态行为。进一步,讨论了熔渣初始温度和冷却风速对其形变和凝固换热的影响。结果表明,熔渣初始温度越小,铺展因数越小,凝固所需时间延长。而冷却风速(1~3 m/s)对熔渣碰壁过程中的铺展形变和换热的影响都很微小。 相似文献
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Excellent non‐volatile memory characteristics have been demonstrated under the optoelectric conditions for organic phototransistors (OPTs). The high photosensitivity shown as reversible shifts in light‐induced VTH exhibits a large memory window for programming caused by the excited immobile carriers (electron) trapped as a function of the electrical bias and the light intensity. The long life span of stored electrons also reveals promising behavior with respect to data retention as well as the electrical reliability to serve as a data storage medium with the non‐volatile memory characteristic in OPTs. The VTH recovery accelerated by the reversible bias stress for the stored charges under irradiation shows that the erasing behavior is clearly brought by the discharge process of long‐lived electrons occupied in deep states. Plausible mechanisms in the energy band are discussed for the programming and erasing process, which provides a fundamental understanding of the intrinsic charge storage behavior in OPTs. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
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Teuku Azuar Rizal Muhammad Amin Syamsul Bahri Widodo Nazaruddin Abdul Rachman Fazri Amir Nurhalim Pane Teuku Meurah Indra Mahlia 《Entropy (Basel, Switzerland)》2022,24(1)
Indonesia has been blessed with excellent solar heat distribution, which can be used as renewable energy to heat water. Various technologies have been developed to utilize these inexhaustible thermodynamic resources, in the form of photons arrays, converted into concentrated heat for daily use, i.e., solar water heater. This renewable-based water heating system can provide significant energy efficiency, benefit the environment, and reduce energy use costs. This experimental study attempts to harvest the energy from the sun using a cylindrical through collector (CTC) type solar concentrator. The CTC was made of the solar reflective film (SRF) affixed to concentrator collector surfaces which was then mounted on an adjustable angle frame of the concentrator collector support. The heat generated from the concentrator was stored in water, and phase change material is embedded in the system to retain the heat longer. The research was carried out in Langsa City, Aceh, Indonesia. The results showed that water heaters using CTC systems could produce 16 L of hot water retained at 40–60 °C for four hours. With the addition of beeswax, the water temperature of the same capacity can be maintained at 40–60 °C for around 5 h. This technology demonstrated an excellent result that produces as much as 60 L of water per day, increasing solar thermal energy efficiency. This technology presented a great potential for replication or even for further development on an industrial scale. 相似文献
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Jian Xia Zixuan Wang Rui Yang Tianci Wang Junjie Gong Yunxiao Dong Zhiyuan Li Jiaping Yao Qiang He Xiaomin Cheng Zengguang Cheng Peng Zhou Xiangshui Miao 《Laser \u0026amp; Photonics Reviews》2024,18(4):2300722
Phase-change-materials (PCMs) integrated photonics have attracted extensive attention in the field of optical neural networks. However, present PCMs-integrated photonics are still far from meeting the requirements in real-world applications due to its unsatisfactory endurance (<3000 cycles) and extinction ratio (ER<20 dB). Here, ultrahigh endurance (>30 000 cycles) and large ER (≥50 dB) are achieved in the photonic device by introducing a trench structure to the indium tin oxide (ITO) heater and utilizing tin-doped Ge2Sb2Te5 (Sn-GST) as PCMs. This performance represents a landmark in the PCMs-integrated photonics, since it solves the problem of poor endurance of ITO heaters and can be comparable to the state-of the-art devices in terms of endurance and ER. This excellent endurance and ER stem from the trench structure and high optical contrast PCM of Sn-GST. Trench structure improves the heating efficiency of the ITO heater and effectively alleviates the thermal stress imposed on the ITO heater, resulting in ultrahigh endurance of the device. Sn-doping is also beneficial to the endurance and ER improvement, because it can effectively reduce the crystallization temperature and increase the absorption coefficient of the PCM layer. This work provides a new technology for the development of programmable photonics with ultrahigh endurance. 相似文献
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OpticalRecordingPerformanceofIn_(47)Sb_(14)Te_(39)PhaseChangeThinFilmsusing514.5nmWavelengthLaserBeam¥MENLiqiu;JIANGFusong;GAN?.. 相似文献
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The present work presents a fast and simple new experimental method, designed to enhance the observation and characterization of thermal phenomena at microscale. Supercooling of water was carried out in micro-channels and recorded with a high-frequency infrared camera. The method is based on the coupling of microfluidics, infrared thermography, and inverse techniques. The objective is to extract a maximum of information from the experiment to perform advanced characterization of the system. First, a thermal modeling of such a system was written, then the image processing from infrared recordings allowed estimating the thermal properties (diffusivity) and the source term (energy released by the phase change). The novelty of the approach is the ability of measuring the heat released by the phase change and using this displacement to calculate the ice front propagation velocity and thermal properties. This method is appropriate for many other applications and is mainly devoted to the characterization of fluids during phase change at microscale. 相似文献
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研究了钛宝石激光器增益介质两端的两块双色镜的相移色散,发现反射相移在中心波长附近发生了突变,由此而造成反射相移色散在此点是不连续的,并对影响反射相移突变点的因素进行了详细的研究。 相似文献
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用变温拉曼光谱对相变过程的研究表明,液晶化合物的初始晶态与熔融后缓慢降温得到的晶态并不吻合,两个状态下分子尾链的构象及刚性核部分的构象不同导致分子的聚集状态不同。西佛碱型液晶化合物VO10相变过程中,在晶态到液晶态相转变过程中,烷氧基尾链链内构象发生突变,同时有序性降低,刚性核部分两个苯环之间的二面角在相变点时发生明显变化,二面角加大。 相似文献