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Impacts of cone-structured interface and aperiodicity on nanoscale thermal transport in Si/Ge superlattices

Pengfei JI, Yiming RONG, Yuwen ZHANG, Yong TANG

《能源前沿(英文)》 2018年 第12卷 第1期   页码 137-142 doi: 10.1007/s11708-018-0532-8

摘要: Si/Ge superlattices are promising thermoelectric materials to convert thermal energy into electric power. The nanoscale thermal transport in Si/Ge superlattices is investigated via molecular dynamics (MD) simulation in this short communication. The impact of Si and Ge interface on the cross-plane thermal conductivity reduction in the Si/Ge superlattices is studied by designing cone-structured interface and aperiodicity between the Si and Ge layers. The temperature difference between the left and right sides of the Si/Ge superlattices is set up for nonequilibrium MD simulation. The spatial distribution of temperature is recorded to examine whether the steady-state has been reached. As a crucial factor to quantify thermal transport, the temporal evolution of heat flux flowing through Si/Ge superlattices is calculated. Compared with the even interface, the cone-structured interface contributes remarkable resistance to the thermal transport, whereas the aperiodic arrangement of Si and Ge layers with unequal thicknesses has a marginal influence on the reduction of effective thermal conductivity. The interface with divergent cone-structure shows the most excellent performance of all the simulated cases, which brings a 33% reduction of the average thermal conductivity to the other Si/Ge superlattices with even, convergent cone-structured interfaces and aperiodic arrangements. The design of divergent cone-structured interface sheds promising light on enhancing the thermoelectric efficiency of Si/Ge based materials.

关键词: thermoelectric material     thermal transport     Si/Gesuperlattics     molecular dynamics (MD)    

Plasma enhanced chemical vapor deposition of excellent a-Si:H passivation layers for a-Si:H/c-Si heterojunction

Lei ZHAO,Wenbin ZHANG,Jingwei CHEN,Hongwei DIAO,Qi WANG,Wenjing WANG

《能源前沿(英文)》 2017年 第11卷 第1期   页码 85-91 doi: 10.1007/s11708-016-0437-3

摘要: The intrinsic a-Si:H passivation layer inserted between the doped a-Si:H layer and the c-Si substrate is very crucial for improving the performance of the a-Si:H/c-Si heterojunction (SHJ) solar cell. The passivation performance of the a-Si:H layer is strongly dependent on its microstructure. Usually, the compact a-Si:H deposited near the transition from the amorphous phase to the nanocrystalline phase by plasma enhanced chemical vapor deposition (PECVD) can provide excellent passivation. However, at the low deposition pressure and low deposition power, such an a-Si:H layer can be only prepared in a narrow region. The deposition condition must be controlled very carefully. In this paper, intrinsic a-Si:H layers were prepared on n-type Cz c-Si substrates by 27.12 MHz PECVD at a high deposition pressure and high deposition power. The corresponding passivation performance on c-Si was investigated by minority carrier lifetime measurement. It was found that an excellent a-Si:H passivation layer could be obtained in a very wide deposition pressure and power region. Such wide process window would be very beneficial for improving the uniformity and the yield for the solar cell fabrication. The a-Si:H layer microstructure was further investigated by Raman and Fourier transform infrared (FTIR) spectroscopy characterization. The correlation between the microstructure and the passivation performance was revealed. According to the above findings, the a-Si:H passivation performance was optimized more elaborately. Finally, a large-area SHJ solar cell with an efficiency of 22.25% was fabricated on the commercial 156 mm pseudo-square n-type Cz c-Si substrate with the open-circuit voltage ( ) of up to 0.732 V.

关键词: PECVD     high pressure and high power     a-Si:H microstructure     passivation     heterojunction solar cell    

Analysis of the double-layer α-Si:H emitter with different doping concentrations for α-Si:H/c-Si heterojunction

Haibin HUANG,Gangyu TIAN,Tao WANG,Chao GAO,Jiren YUAN,Zhihao YUE,Lang ZHOU

《能源前沿(英文)》 2017年 第11卷 第1期   页码 92-95 doi: 10.1007/s11708-016-0432-8

摘要: Double-layer emitters with different doping concentrations (DLE) have been designed and prepared for amorphous silicon/crystalline silicon (α-Si:H/c-Si) heterojunction solar cells. Compared with the traditional single layer emitter, both the experiment and the simulation (AFORS-HET, http://www.paper.edu.cn/html/releasepaper/2014/04/282/) prove that the double-layer emitter increases the short circuit current of the cells significantly. Based on the quantum efficiency (QE) results and the current-voltage-temperature analysis, the mechanism for the experimental results above has been investigated. The possible reasons for the increased current include the enhancement of the QE in the short wavelength range, the increase of the tunneling probability of the current transport and the decrease of the activation energy of the emitter layers.

关键词: double-layer emitter     α-Si:H/c-Si heterojunction solar cell     short circuit current     quantum efficiency     current-voltage-temperature    

Stability and dynamics of rotor system with 45° slant crack on shaft

Yanli LIN, Xiaohui SI, Fulei CHU

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 203-213 doi: 10.1007/s11465-011-0131-4

摘要:

Crack on a shaft is one of the common damages in a rotor system. In this paper, transverse vibrations are calculated to compare the influences of transverse crack and slant crack on the rotor system. Results show that the vibration amplitude of the rotor system with a 45° slant crack on the shaft is larger than that with a transverse crack when the two types of crack have the same depth and the rotor system runs in the same condition. Stability and dynamic characteristics of the rotor system with a 45° slant crack on the shaft under torsional excitation are analyzed by considering opening and closing of the crack. It is shown that the instability of the transverse vibration of the rotor system increases with increasing difference between the bending stiffness in two main directions, and the vibration is stable when the two bending stiffness are identical. The spectrum analysis of the steady-state response reveals that the gravity and the eccentricity produce different frequency components, and when the two bending stiffness are identical, the multiple frequency components of the torsional excitation disappear. Further investigation shows that the vibration amplitudes in combined frequencies increase rapidly in transversal, torsional, and axial vibration with increasing slant crack depth. The results are helpful for the understanding the dynamic behavior of a rotor system with a slant crack on a shaft and can be used for the detection of the slant crack on a shaft.

关键词: rotor dynamics     slant crack     stability     torsional excitation     open and close    

Mercury enrichment in

Chunhao Dai, Pufeng Qin, Zhangwei Wang, Jian Chen, Xianshan Zhang, Si Luo

《环境科学与工程前沿(英文)》 2017年 第11卷 第1期 doi: 10.1007/s11783-017-0892-z

摘要: Mercury enrichment in response to elevated atmospheric mercury concentrations in the organs of rape ( ) was investigated. Elevated soil mercury content had significant impact on mercury accumulation in rape stems, roots, seeds and seed coats. Leaf mercury in the leaves was mostly affected by atmospheric input while the stems were mostly affected by soil concentrations. Mercury in the aboveground plant tissue mainly derived from atmospheric absorption, and atmospheric mercury absorption in leaves was higher than that in the stems. Mercury enrichment in response to elevated atmospheric mercury concentrations in the organs of rape ( ) was investigated using an open top chamber fumigation experiment and a soil mercury enriched cultivation experiment. Results indicate that the mercury concentration in leaves and stems showed a significant variation under different concentrations of mercury in atmospheric and soil experiments while the concentration of mercury in roots, seeds and seed coats showed no significant variation under different atmospheric mercury concentrations. Using the function relation established by the experiment, results for atmospheric mercury sources in rape field biomass showed that atmospheric sources accounted for at least 81.81% of mercury in rape leaves and 32.29% of mercury in the stems. Therefore, mercury in the aboveground biomass predominantly derives from the absorption of atmospheric mercury.

关键词: Open top chamber     Gaseous elemental mercury (GEM)     Soil Mercury     Brassica napus    

Laser ablation of block copolymers with hydrogen-bonded azobenzene derivatives

Jintang Huang, Youju Huang, Si Wu

《化学科学与工程前沿(英文)》 2018年 第12卷 第3期   页码 450-456 doi: 10.1007/s11705-018-1735-6

摘要:

Supramolecular assemblies (PS-b-P4VP(AzoR)) are fabricated by hydrogen-bonding azobenzene derivatives (AzoR) to poly(4-vinyl pyridine) blocks of polystyrene-block-poly(4-vinyl pyridine) (PS-b-P4VP). PS-b-P4VP(AzoR) forms phase separated nanostructures with a period of ~75–105 nm. A second length scale structure with a period of 2 µm is fabricated on phase separated PS-b-P4VP(AzoR) by laser interference ablation. Both the concentration and the substituent of AzoR in PS-b-P4VP(AzoR) affect the laser ablation process. The laser ablation threshold of PS-b-P4VP(AzoR) decreases as the concentration of AzoR increases. In PS-b-P4VP(AzoR) with different substituents (R= CN, H, and CH3), ablation thresholds follow the trend: PS-b-P4VP(AzoCN)<PS-b-P4VP(AzoCH3)<PS-b-P4VP(AzoH). This result indicates that the electron donor group (CH3) and the electron acceptor group (CN) can lower the ablation threshold of PS-b-P4VP(AzoR).

关键词: laser ablation     block copolymers     hydrogen-bond     azobenzene derivatives     supramolecular assembly    

Numerical simulation of charge stratifications to improve combustion and NO formation of lean-burn SI

Zhijun PENG ,

《能源前沿(英文)》 2009年 第3卷 第3期   页码 353-358 doi: 10.1007/s11708-009-0035-8

摘要: The influences of charge stratification on spark ignition (SI) engine combustion and NO emission were analyzed using a phenomenological model. The mixture in the cylinder was divided spherically into three parts: a central core with a stoichiometric air-fuel charge, a dilution region without any combustible charge, and a mixing region lying between the core and the dilution region. Three mixture stratification parameters such as the extent of dilution in the mixing region, the extent of combustible charge in the mixing region, and the gradient of stratification in the mixing region were investigated. The results indicate that the extent of combustible charge in the mixing region could reduce in-cylinder NO formation significantly, compared with the extent of dilution in the mixing region. As long as the degree of dilution in the mixing region is within the dilution limit of the combustible charge, the gradient of dilution has little effect on combustion and NO formation.

关键词: charge stratification     SI engine     lean-burn combustion     NO emission    

Ga(X)N/Si nanoarchitecture: An emerging semiconductor platform for sunlight-powered water splitting toward

《能源前沿(英文)》 doi: 10.1007/s11708-023-0881-9

摘要: Sunlight-powered water splitting presents a promising strategy for converting intermittent and virtually unlimited solar energy into energy-dense and storable green hydrogen. Since the pioneering discovery by Honda and Fujishima, considerable efforts have been made in this research area. Among various materials developed, Ga(X)N/Si (X = In, Ge, Mg, etc.) nanoarchitecture has emerged as a disruptive semiconductor platform to split water toward hydrogen by sunlight. This paper introduces the characteristics, properties, and growth/synthesis/fabrication methods of Ga(X)N/Si nanoarchitecture, primarily focusing on explaining the suitability as an ideal platform for sunlight-powered water splitting toward green hydrogen fuel. In addition, it exclusively summarizes the recent progress and development of Ga(X)N/Si nanoarchitecture for photocatalytic and photoelectrochemical water splitting. Moreover, it describes the challenges and prospects of artificial photosynthesis integrated device and system using Ga(X)N/Si nanoarchitectures for solar water splitting toward hydrogen.

关键词: Ga(X)N/Si nanoarchitecture     artificial photosynthesis     water splitting     solar toward hydrogen    

旋转体自身驱动的硅微机械陀螺

张福学,毛旭,张伟

《中国工程科学》 2006年 第8卷 第8期   页码 23-27

摘要:

报道了一种利用旋转体自身角速度作为驱动力,通过各向异性刻蚀硅片制作的硅微机械陀螺。介绍了该陀螺敏感结构(硅摆)的设计、制作与封装工艺,用仿真器测试了旋转体的角速率。模拟试验和性能测试表明,该陀螺结构原理正确,可用于敏感旋转体的偏航或俯仰角速度,以及旋转体自身的角速度。

关键词:     各向异性腐蚀     角速度     仿真器    

Fabrication of Si-based three-dimensional microbatteries: A review

Chuang YUE, Jing LI, Liwei LIN

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 459-476 doi: 10.1007/s11465-017-0462-x

摘要:

High-performance, Si-based three-dimensional (3D) microbattery systems for powering micro/nano-electromechanical systems and lab-on-chip smart electronic devices have attracted increasing research attention. These systems are characterized by compatible fabrication and integratibility resulting from the silicon-based technologies used in their production. The use of support substrates, electrodes or current collectors, electrolytes, and even batteries used in 3D layouts has become increasingly important in fabricating microbatteries with high energy, high power density, and wide-ranging applications. In this review, Si-based 3D microbatteries and related fabrication technologies, especially the production of micro-lithium ion batteries, are reviewed and discussed in detail in order to provide guidance for the design and fabrication.

关键词: three-dimensional (3D)     wafer-scale     Si-based anode     micro-LIBs     thin-film deposition    

LC/MS/MS and radioisotope method combined for recognizing the affinity between catalpol and OCT2 transporter

Zhiyu ZHANG, Changxiao LIU, Duanyun SI, Rong LU, Xiulin YI

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 436-442 doi: 10.1007/s11705-012-1222-4

摘要: More and more herbal medicines are found to be the substrates of drug transporters. In this paper, chromatography/tandem mass spectrometry (LC/MS/MS) combined with radioisotope method was used for the quantification of catalpol, a traditional Chinese medicine, to study the affinity relationship between herbal medicines and transporters. Catalpol uptake experiment was carried out by using several transporters (OAT1, OCT2, OAT3, OATP1B1 and OATP2B1). And samples were precipitated with methanol and quantified with LC/MS/MS. The results show that catalpol has a good affinity with OCT2-transfected S2 cells. After studying drug-drug interaction between catalpol and C-tetraethylammonium (TEA), we found that catalpol is able to facilitate TEA transport mediated by OCT2, suggesting that catalpol could probably be a new promoter of OCT2.

关键词: catalpol     LC/MS/MS     OCT2    

Promoting Si-graphite composite anodes with SWCNT additives for half and NCM811 full lithium ion batteries

Jingning SHAN, Xiaofang YANG, Chao YAN, Yiguang JU, Lin CHEN, Fang ZHAO

《能源前沿(英文)》 2019年 第13卷 第4期   页码 626-635 doi: 10.1007/s11708-019-0650-y

摘要: Single wall carbon nanotube (SWCNT) additives were formulated into µm-Si-graphite composite electrodes and tested in both half cells and full cells with high nickel cathodes. The critical role of small amount of SWCNT addition (0.2 wt%) was found for significantly improving delithiation capacity, first cycle coulombic efficiency (FCE), and capacity retention. Particularly, Si (10 wt%)-graphite electrode exhibits 560 mAh/g delithiation capacity and 92% FCE at 0.2 C during the first charge-discharge cycle, and 91% capacity retention after 50 cycles (0.5 C) in a half cell. Scanning electron microscope (SEM) was used to illustrate the electrode morphology, compositions and promoting function of the SWCNT additives. In addition, full cells assembled with high nickel-NCM811 cathodes and µm-Si-graphite composite anodes were evaluated for the consistence between half and full cell performance, and the consideration for potential commercial application. Finally, criteria to assess Si-containing anodes are proposed and discussed from an industrial perspective.

关键词: lithium-ion battery     Si anode     Si-graphite composite     single wall carbon nanotube (SWCNT)     NCM811    

Current progress on scaffolds of tissue engineering heart valves

DONG Nianguo, SHI Jiawei, CHEN Si, HONG Hao, HU Ping

《医学前沿(英文)》 2008年 第2卷 第3期   页码 229-234 doi: 10.1007/s11684-008-0043-9

摘要: Tissue engineering heart valves (TEHV) may be the most promising valve substitute, but the study has been relatively stagnant in the recent five years due to the special position, function and mechanical property of heart valves. It is one of the key factors to select an ideal scaffold material in the construction of TEHV. And this article will briefly review the current research and progress on the scaffolds of TEHV, especially based on Chinese works.

关键词: function     scaffold     promising     research     engineering    

Ultrathin microcrystalline hydrogenated Si/Ge alloyed tandem solar cells towards full solar spectrum

Yu Cao, Xinyun Zhu, Xingyu Tong, Jing Zhou, Jian Ni, Jianjun Zhang, Jinbo Pang

《化学科学与工程前沿(英文)》 2020年 第14卷 第6期   页码 997-1005 doi: 10.1007/s11705-019-1906-0

摘要: Thin film solar cells have been proved the next generation photovoltaic devices due to their low cost, less material consumption and easy mass production. Among them, micro-crystalline Si and Ge based thin film solar cells have advantages of high efficiency and ultrathin absorber layers. Yet individual junction devices are limited in photoelectric conversion efficiency because of the restricted solar spectrum range for its specific absorber. In this work, we designed and simulated a multi-junction solar cell with its four sub-cells selectively absorbing the full solar spectrum including the ultraviolet, green, red as well as near infrared range, respectively. By tuning the Ge content, the record efficiency of 24.80% has been realized with the typical quadruple junction structure of a-Si:H/a-Si Ge :H/µc-Si:H/µc-Si Ge :H. To further reduce the material cost, thickness dependent device performances have been conducted. It can be found that the design of total thickness of 4 m is the optimal device design in balancing the thickness and the . While the design of ultrathin quadruple junction device with total thickness of 2 m is the optimized device design regarding cost and long-term stability with a little bit more reduction in . These results indicated that our solar cells combine the advantages of low cost and high stability. Our work may provide a general guidance rule of utilizing the full solar spectrum for developing high efficiency and ultrathin multi-junction solar cells.

关键词: thin films     solar cells     quadruple junction solar cell     amorphous silicon     silicon germanium alloy     quantum efficiency    

Recent advances in system reliability optimization driven by importance measures

Shubin SI, Jiangbin ZHAO, Zhiqiang CAI, Hongyan DUI

《工程管理前沿(英文)》 2020年 第7卷 第3期   页码 335-358 doi: 10.1007/s42524-020-0112-6

摘要: System reliability optimization problems have been widely discussed to maximize system reliability with resource constraints. Birnbaum importance is a well-known method for evaluating the effect of component reliability on system reliability. Many importance measures (IMs) are extended for binary, multistate, and continuous systems from different aspects based on the Birnbaum importance. Recently, these IMs have been applied in allocating limited resources to the component to maximize system performance. Therefore, the significance of Birnbaum importance is illustrated from the perspective of probability principle and gradient geometrical sense. Furthermore, the equations of various extended IMs are provided subsequently. The rules for simple optimization problems are summarized to enhance system reliability by using ranking or heuristic methods based on IMs. The importance-based optimization algorithms for complex or large-scale systems are generalized to obtain remarkable solutions by using IM-based local search or simplification methods. Furthermore, a general framework driven by IM is developed to solve optimization problems. Finally, some challenges in system reliability optimization that need to be solved in the future are presented.

关键词: importance measure     system performance     reliability optimization     optimization rules     optimization algorithms    

标题 作者 时间 类型 操作

Impacts of cone-structured interface and aperiodicity on nanoscale thermal transport in Si/Ge superlattices

Pengfei JI, Yiming RONG, Yuwen ZHANG, Yong TANG

期刊论文

Plasma enhanced chemical vapor deposition of excellent a-Si:H passivation layers for a-Si:H/c-Si heterojunction

Lei ZHAO,Wenbin ZHANG,Jingwei CHEN,Hongwei DIAO,Qi WANG,Wenjing WANG

期刊论文

Analysis of the double-layer α-Si:H emitter with different doping concentrations for α-Si:H/c-Si heterojunction

Haibin HUANG,Gangyu TIAN,Tao WANG,Chao GAO,Jiren YUAN,Zhihao YUE,Lang ZHOU

期刊论文

Stability and dynamics of rotor system with 45° slant crack on shaft

Yanli LIN, Xiaohui SI, Fulei CHU

期刊论文

Mercury enrichment in

Chunhao Dai, Pufeng Qin, Zhangwei Wang, Jian Chen, Xianshan Zhang, Si Luo

期刊论文

Laser ablation of block copolymers with hydrogen-bonded azobenzene derivatives

Jintang Huang, Youju Huang, Si Wu

期刊论文

Numerical simulation of charge stratifications to improve combustion and NO formation of lean-burn SI

Zhijun PENG ,

期刊论文

Ga(X)N/Si nanoarchitecture: An emerging semiconductor platform for sunlight-powered water splitting toward

期刊论文

旋转体自身驱动的硅微机械陀螺

张福学,毛旭,张伟

期刊论文

Fabrication of Si-based three-dimensional microbatteries: A review

Chuang YUE, Jing LI, Liwei LIN

期刊论文

LC/MS/MS and radioisotope method combined for recognizing the affinity between catalpol and OCT2 transporter

Zhiyu ZHANG, Changxiao LIU, Duanyun SI, Rong LU, Xiulin YI

期刊论文

Promoting Si-graphite composite anodes with SWCNT additives for half and NCM811 full lithium ion batteries

Jingning SHAN, Xiaofang YANG, Chao YAN, Yiguang JU, Lin CHEN, Fang ZHAO

期刊论文

Current progress on scaffolds of tissue engineering heart valves

DONG Nianguo, SHI Jiawei, CHEN Si, HONG Hao, HU Ping

期刊论文

Ultrathin microcrystalline hydrogenated Si/Ge alloyed tandem solar cells towards full solar spectrum

Yu Cao, Xinyun Zhu, Xingyu Tong, Jing Zhou, Jian Ni, Jianjun Zhang, Jinbo Pang

期刊论文

Recent advances in system reliability optimization driven by importance measures

Shubin SI, Jiangbin ZHAO, Zhiqiang CAI, Hongyan DUI

期刊论文