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961.
《International Journal of Hydrogen Energy》2019,44(41):23188-23195
We study hydrogen storage properties of Nb doped ZrNiH3 using the first-principles calculations based on density functional theory (DFT). To achieve such calculations, we used full potential linearized augmented plane waves (FP-LAPW) method implanted in WIEN2K code. Total energy and density of states (DOS) are computed for Zr1-xNbxNiH3 (x = 0 and 0.1). It turns out that substituting 10% of zirconium by niobium in ZrNiH3 matrix involves a destabilization of the system. This destabilization is induced by the formation of a new hybridization between niobium and hydrogen atoms. Furthermore, the thermodynamic stability in terms of its energy of formation, as well as the capacity of the material to store hydrogen are discussed. Noteworthy that from FP-LAPW we report that Nb doped ZrNiH3 lower the desorption temperature to 305.77 K without significant reduction of the hydrogen storage capacity. This lowering of the temperature desorption makes the material very useful for hydrogen storage in solids. 相似文献
962.
目的 为使博物院文创产品创新设计的决策过程充分考虑用户的需求偏好特征,对博物院文创产品设计的核心属性因素进行探究。方法 通过文化层次法提炼出博物院文创产品的设计要素,并运用粗糙集与语意差异法构建知识表达系统。然后通过属性约简和重要度计算,得出对感性意象语意影响较大的设计要素,进而定性与定量地获取博物馆文创产品的设计模式。以安徽博物院为例,提取出核心属性并筛选出最大程度影响用户感性意象简洁大方的设计要素为文化意象色彩,其次为文化情感属性,最后为文化象征意义与交互使用体验。结论 通过对博物院文创产品设计的用户需求关键因素进行分析与探究,提出了博物院文创产品的设计思路,进而为博物馆文创产品的设计、开发提供了参考依据。 相似文献
963.
《International Journal of Hydrogen Energy》2019,44(47):25599-25606
The synthesis of photocatalysts with controlled facets has become an important approach to enhance the H2 evolution activity. However, the relationship between different exposed facets of heterojunctions and photocatalytic performance still needs to be further investigated. In this study, three types of CdS@ZnO core-shell architectures with tunable heteroinnerfaces were fabricated. Hexagonal wurtzite ZnO samples with different percentages of exposed (001) facet showed up as rod-like, short rod-like and disk-like morphologies, respectively, subsequently, self-assembled flower-like CdS coated on the whole facet of ZnO, constructing a core-shell nanostructure with the corresponding tunable heterointerfaces. Under visible-light irradiation, it was discovered that the performance of hydrogen evolution is proportional to the ratio of (001) facet of ZnO in CdS@ZnO core-shell structures. Further photoelectric tests indicated that the (001) facet of ZnO by CdS modification can form a more perfect combination than that of (100) facet of ZnO, which exhibits higher electron conduction and separation performance. 相似文献
964.
《Ceramics International》2022,48(11):15261-15267
An effective and simple synthesis of high-performance materials exerts a significant influence on low-cost commercial production with high production efficiency. In the present work, the effects of intrinsic factors on the microwave dielectric properties of reaction-sintering Mg0.5Zr0.5NbO4 ceramics were quantified through crystal chemistry, Raman analysis, and bond characteristics. Pure-phase and low-loss Mg0.5Zr0.5NbO4 ceramics were synthesized with an effective and simple reaction-sintering procedure. Detailed Raman vibrations with complete mode assignments were firstly investigated to characterize the lattice vibration. Rietveld refinement and Raman analysis confirmed the formation of pure-phase MgZrNb2O8 ceramics even with the reaction-sintering process. Moreover, well-distributed microstructure with enhanced densification (nearly full density) was verified through SEM and element mapping. Through the chemical bond theory, the dielectric constant was dominated by the Nb–O bond ionicity (fiNb-O). The Q × f was strongly related to the lattice energy (UNb–O) and bond energy (ENb-O) of the Nb–O bond, while the τf value was influenced by the coefficient of thermal expansion of the Mg–O bond (αMg-O), providing guidance for performance modification of Mg0.5Zr0.5NbO4 systems. Excellent microwave dielectric properties for the samples sintered at 1350 °C: εr = 28.6, Q × f = 82,000 GHz (7.1 GHz) and τf = ?47 ppm/°C were obtained via the reaction sintering process, exhibiting enormous potential for industrial production. 相似文献
965.
To increase the richness of the extracted text modality feature information and deeply explore the semantic similarity between the modalities. In this paper, we propose a novel method, named adaptive weight multi-channel center similar deep hashing (AMCDH). The algorithm first utilizes three channels with different configurations to extract feature information from the text modality; and then adds them according to the learned weight ratio to increase the richness of the information. We also introduce the Jaccard coefficient to measure the semantic similarity level between modalities from 0 to 1, and utilize it as the penalty coefficient of the cross-entropy loss function to increase its role in backpropagation. Besides, we propose a method of constructing center similarity, which makes the hash codes of similar data pairs close to the same center point, and dissimilar data pairs are scattered at different center points to generate high-quality hash codes. Extensive experimental evaluations on four benchmark datasets show that the performance of our proposed model AMCDH is significantly better than other competing baselines. The code can be obtained from https://github.com/DaveLiu6/AMCDH.git. 相似文献
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969.
Red-emitting phosphors LaBSiO5:Eu3+ and LaBSiO5:Eu3+, Al3+ were synthesized by the conventional solid state method at 1100 °C. The structure and luminescent properties of these phosphors are investigated. LaBSiO5:Eu3+ and LaBSiO5:Eu3+, Al3+ could be efficiently excited by near ultraviolet light with the strongest excitation peak at 395 nm. The main emission peak is located at around 616 nm, which corresponds to the transition of 5D0 → 7F2 of Eu3+ ions. The emission intensity of LaBSiO5:Eu3+ was enhanced by introducing Al3+ ions. Compared with Y2O2S:0.05Eu3+, the sample La0.70B0.75SiO5:0.30Eu3+, 0.25Al3+ shares the intense red emission, and its emission intensity is about 3.8 times as strong as that of Y2O2S:0.05Eu3+ under 395 nm light excitation. Bright red light can be observed from the red LED based on La0.70B0.75SiO5:0.30Eu3+, 0.25Al3+, hence La0.70B0.75SiO5:0.30Eu3+, 0.25Al3+ maybe find application on near-UV InGaN-based white LEDs. 相似文献
970.
针对传统基于视频或传感器的跌倒检测方法中环境依赖、空间受限等问题,提出了一种基于无线信道状态信息的跌倒无源检测方法Fallsense。该方法利用普适、低成本的商用WiFi设备,首先采集无线信道状态数据并对数据进行预处理,然后设计动作—信号分析模型,建立轻量级动态模板匹配算法以从时序信道数据中实时检测出承载真实跌倒事件的相关片段。大量实际环境下的实验表明,Fallsense可以实现较高的准确率以及较低的误报率,准确率达到95%,误报率为2.44%。与经典WiFall系统相比,Fallsense将时间复杂度从WiFall的O(mN log N)降低到O(N)(N是样本数,m是特征数),且准确率提高了2.69%,误报率下降了4.66%。实验结果表明,所提方法是一种快速高效的无源跌倒检测方法。 相似文献