1,230 research outputs found
Design of VisSWIR continuous zoom optical system
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For 640 pixel×512 pixel cooled staring focal plane array detector, a VisSWIR wideband continuous zoom optical system with 7X zoom range is presented based on the pattern of the negative zoom group and compensating lens group. The zoom system provides continuous changed in the field of view from narrow to the wide. The zoom optical system works in the range of 0.4μm∼1.7μm, F number is 4, the pixel of the detector is 15μm. It realizes 20mm∼140mm continuous zoom with a smooth zoom path and provided high image quality with the whole zoom range, the zoom ratio is 7:1. The modulation transfer function(MTF) for the system is above 0.5 within the whole focal length range at spatial frequency of 34lp/mm and it almost approaches the diffraction limit. RMS value of spot diameter was investigation, the maximum distortion value is less than 5% and the surface type of all lens applied is spherical. Moreover, the cam curve after optimization is given by the optical design software Code V macro. The design results provide that the zoom system has the small size, high resolution, excellent image quality and the smooth cam curve etc. © 2017 SPIE.</p
Adaptive state-of-health temperature sensitivity characteristics for durability improvement of PEM fuel cells
No full textTo obtain the temperature sensitivity characteristics of the proton exchange membrane fuel cell under different degradation levels, accelerated durability tests and temperature sensitivity tests of the fuel cell are first performed, and the temperature characteristics under different degradation states are analyzed by electrochemical impedance spectroscopy and polarization curve. Besides, an adaptive state-of-health transient thermal model of fuel cells is developed to investigate the effect of operating temperature on the internal gas concentration and hydrothermal distribution characteristics of the fuel cell from a mechanistic perspective. The experimental results of temperature sensitivity validate that the adaptive state-of-health transient thermal model can effectively monitor the steady and transient performance of the fuel cell. Subsequently, a mathematical model is proposed to describe the relationship among the load current, state of health, and optimal temperature using the temperature sensitivity test data and the transient thermal model of the adaptive state of health, which provides important insights into the optimal temperature range tailored to the current state of health of fuel cells to ensure efficient and stable operation of fuel cells all the time and contributes to the fine design of an optimal degradation adaptive temperature control strategy
Ji tai 23Na 87Rb fen zi de ji xing chao leng qi ti
No full textPh.D.This thesis describes the creation and collisional investigations of a high density sample of ultracold ground-state dipolar ²³Na⁸⁷Rb molecules. These molecules are produced by transferring weakly-bound Feshbach molecules to the ground state through a two-photon Raman process. To this end, an ultrastable and narrow linewidth Raman laser system is constructed by locking two diode lasers to a dual-wavelength coated high-finesse optical cavity. After identifying the two-photon pathway, a Stimulated Raman adiabatic passage with efficiency up to 93% is achieved, which allows us to produce a sample of absolute ground-state ²³Na⁸⁷Rb molecules with density as high as 6×10¹¹ cm⁻³. An effective electric dipole moment over 1 Debye, the largest ever achieved in ultracold molecules, is also demonstrated by applying a static electric field.Although the absolute ground-state ²³Na⁸⁷Rb molecules are chemically stable, an unexpected fast two-body loss is observed. Thus, collisions of the molecules prepared to different internal states, which is achieved by combining the high-resolution two-photon Raman process with extra microwave pulses, are investigated. Loss rates of the ground-state molecules with different dipolar interaction strength are also measured. These results pave the way toward the investigations of ultracold gases with strong dipolar interactions本論文介紹了高密度基態超冷極性鈉銣分子的製備以及對其碰撞性質的研究。為了把分子從弱束縛費什巴赫態轉移到基態，我們搭建了一套超穩且具備超窄線寬的激光系統。通過合適的雙光子拉曼過程，我們實現了93%的轉移效率，成功製備了密度高達6×10¹¹ cm⁻³的基態超冷鈉銣分子。通過外加靜電場，我們成功誘導基態分子達到1 Debye的等效電偶極矩，這是目前在超冷分子里實現的最大等效電偶極矩。儘管基態鈉銣分子是化學穩定的，我們依然在實驗上觀測到了分子的嚴重損耗。通過對分子內態的超精密操控，我們研究了分子在有化學反應和沒有化學反應發生情況下的損耗行為，並且觀測到了非常相似的動力學過程。此外，我們還研究了在不同偶極相互作用強度下的分子損耗，在超冷溫度下同時觀測到了s分波和d分波的貢獻。雖然這些結果還不足以確定基態分子的損耗機制，我們的成果對極性超冷氣體的研究具有重要意義。Guo, Mingyang = 基態23Na 87Rb分子的極性超冷氣體 / 郭鳴阳."December 2017."23, 87 in title are superscript.Thesis Ph.D. Chinese University of Hong Kong 2018.Includes bibliographical references (leaves 129-156).Abstracts also in Chinese.Title from PDF title page (viewed on 20, April, 2021).Guo, Mingyang = Ji tai 23Na 87Rb fen zi de ji xing chao leng qi ti / Guo Mingyang
Ship path planning methods: a state-of-the-art survey
No full textThe rapid increase in the number and size of commercial ships has led to growing congestion in marine transportation, significantly heightening the risk of ship collisions that pose serious risks to crew lives, environmental and property damage. As a result, ship collision avoidance has been a critical research focus, leading to the development of diverse path planning algorithms. This study presents a systematic review of ship path planning research from 2015 to 2024, aiming to classify the state-of-the-art algorithms, explore their core methodologies, and evaluate their applicability across various maritime scenarios. This review covers five primary categories of ship path planning algorithms. These approaches encompass numerical, graph-based, sampling-based, AI-driven, and hybrid methods. The analysis reveals that AI-driven and hybrid approaches have gained significant momentum in recent years, reflecting a paradigm shift toward more intelligent and flexible path planning systems, with growing attention to real-world applicability and regulatory compliance. This review not only maps the evolution of ship path planning techniques but also identifies promising directions to guide future research and innovation of ship path planning, which makes new and significant contributions to maritime transport evolution from pure manned vessels to the mixed traffic of manned and autonomous ships
Harbin thermal park: transforming an abandoned thermal power plant into green infrastructure
No full textMy research goal was to explore the possibilities of post industrial sites to transform them into green infrastructure by multi-scale approach, making them not only benefit the ecology system in city scale, but also urban environment in local scale, while remaining the industrial beauty of the site
Data from: A study on the Influence of submergence ratio on the transportation of suspended sediment in a partially vegetated channel flow
No full textRiparian or aquatic vegetation thrives with seasons. The understanding of canopies' Submergence-Ratio SR (stems' height to water depth) influence on suspended sediments' transportation is still limited. Thus, Large Eddy Simulations (LES) coupled with the Discrete Phase Method (DPM) are used to investigate the particles' 3-dimensional distribution in a partially vegetated straight channel. The spanwise distribution of particles is quantified by the Probability Density Function (PDF), showing a non-uniformity of particles in time as quantified by the PDF variance. The findings and conclusions: (Ⅰ) With SR rising, the particles' depletion effects exerted by the vegetation-side mixing layer are improved along the interface between vegetated and vegetation-side bare channel region. However, the SR has little effect on the variance of the particles' PDF in the spanwise direction when the mixing layer is fully developed. (Ⅱ) During the developing stage of the over-canopy mixing layer, submerged vegetation with higher SR gain a stronger upwards (vertical) entrainment capability. The case (SR=60%) has a higher sediment concentration than other cases in the fully developed vertical mixing layer region above canopy. (III) The vertical suspension of particles in the vegetation-side bare channel region is analysed. Particles migrating from the vegetated region are entrained into the vegetation-side bare channel region by turbulent structures. Nevertheless, the vertical concentration profile is more uniform in the vegetated region than in the vegetation-side bare channel at the same streamwise location. The cases SR=40% and 60% still have higher sediment concentrations than other cases in the vegetation-side bare channel's upper region.The corresponding author is Dr. Eldad Avital. Mingyang Wang is the first author. Funding provided by: Engineering and Physical Sciences Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000266Award Number:The datasets are produced mainly based on the numerical simulations, some exprimental data is collected from published literatures
sj-pdf-1-cath-10.1177_10760296211068037 - Supplemental material for Efficacy of Recombinant Human Thrombopoietin for the Treatment of Secondary Failure of Platelet Recovery After Allogeneic HSCT
No full textSupplemental material, sj-pdf-1-cath-10.1177_10760296211068037 for Efficacy of Recombinant Human Thrombopoietin for the Treatment of Secondary Failure of Platelet Recovery After Allogeneic HSCT by Yigeng Cao, Mingyang Wang, Biao Shen, Fei Zhao, Rongli Zhang, Xin Chen, Yi He, Weihua Zhai, Qiaoling Ma, Jialin Wei, Yong Huang, Donglin Yang, Aiming Pang, Sizhou Feng, Erlie Jiang and Mingzhe Han in Clinical and Applied Thrombosis/Hemostasis</p
Ultra-bright and highly efficient inorganic based perovskite light-emitting diodes
No full textAbstractInorganic perovskites such as CsPbX3 (X=Cl, Br, I) have attracted attention due to their excellent thermal stability and high photoluminescence quantum efficiency. However, the electroluminescence quantum efficiency of their light-emitting diodes was <1%. We posited that this low efficiency was a result of high leakage current caused by poor perovskite morphology, high non-radiative recombination at interfaces and perovskite grain boundaries, and also charge injection imbalance. Here, we incorporated a small amount of methylammonium organic cation into the CsPbBr3 lattice and by depositing a hydrophilic and insulating polyvinyl pyrrolidine polymer atop the ZnO electron-injection layer to overcome these issues. As a result, we obtained light-emitting diodes exhibiting a high brightness of 91,000 cd m−2 and a high external quantum efficiency of 10.4% using a mixed-cation perovskite Cs0.87MA0.13PbBr3 as the emitting layer. To the best of our knowledge, this is the brightest and most-efficient green perovskite light-emitting diodes reported to date.</jats:p
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