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Metal-based direct hydrogen generation as unconventional high density energy

Shuo XU, Jing LIU

《能源前沿(英文)》 2019年 第13卷 第1期   页码 27-53 doi: 10.1007/s11708-018-0603-x

摘要: Metals are unconventional hydrogen production materials which are of high energy densities. This paper comprehensively reviewed and digested the latest researches of the metal-based direct hydrogen generation and the unconventional energy utilization ways thus enabled. According to the metal activities, the reaction conditions of metals were generalized into three categories. The first ones refer to those which would violently react with water at ambient temperature. The second ones start to react with water after certain pretreatments. The third ones can only react with steam under somewhat harsh conditions. To interpret the metal-water reaction mechanisms at the molecular scale, the molecule dynamics simulation and computational quantum chemistry were introduced as representative theoretical analytical tools. Besides, the state-of-the-art of the metal-water reaction was presented with several ordinary metals as illustration examples, including the material treatment technologies and the evaluations of hydrogen evolution performances. Moreover, the energy capacities of various metals were summarized, and the application potentials of the metal-based direct hydrogen production approach were explored. Furthermore, the challenges lying behind this unconventional hydrogen generation method and energy strategy were raised, which outlined promising directions worth of further endeavors. Overall, active metals like Na and K are appropriate for rapid hydrogen production occasions. Of these metals discussed, Al, Mg and their alloys offer the most promising hydrogen generation route for clean and efficient propulsion and real-time power source. In the long run, there exists plenty of space for developing future energy technology along this direction.

关键词: metal     hydrogen generation     hydrolysis     metal water reaction     clean energy    

Direct writing of electronics based on alloy and metal (DREAM) ink: A newly emerging area and its impact

Qin ZHANG, Yi ZHENG, Jing LIU

《能源前沿(英文)》 2012年 第6卷 第4期   页码 311-340 doi: 10.1007/s11708-012-0214-x

摘要: Electronics, such as printed circuit board (PCB), transistor, radio frequency identification (RFID), organic light emitting diode (OLED), solar cells, electronic display, lab on a chip (LOC), sensor, actuator, and transducer etc. are playing increasingly important roles in people’s daily life. Conventional fabrication strategy towards integrated circuit (IC), requesting at least six working steps, generally consumes too much energy, material and water, and is not environmentally friendly. During the etching process, a large amount of raw materials have to be abandoned. Besides, lithography and microfabrication are typically carried out in “Cleanroom” which restricts the location of IC fabrication and leads to high production costs. As an alternative, the newly emerging ink-jet printing electronics are gradually shaping modern electronic industry and its related areas, owing to the invention of a series of conductive inks composed of polymer matrix, conductive fillers, solvents and additives. Nevertheless, the currently available methods also encounter some technical troubles due to the low electroconductivity, complex sythesis and sintering process of the inks. As an alternative, a fundamentally different strategy was recently proposed by the authors’ lab towards truly direct writing of electronics through introduction of a new class of conductive inks made of low melting point liquid metal or its alloy. The method has been named as direct writing of electronics based on alloy and metal (DREAM) ink. A series of functional circuits, sensors, electronic elements and devices can thus be easily written on various either soft or rigid substrates in a moment. With more and more technical progresses and fundamental discoveries being kept made along this category, it was found that a new area enabled by the DREAM ink electronics is emerging, which would have tremendous impacts on future energy and environmental sciences. In order to promote the research and development along this direction, the present paper is dedicated to draft a comprehensive picture on the DREAM ink technology by summarizing its most basic features and principles. Some important low melting point metal ink candidates, especially the room temperature liquid metals such as gallium and its alloy, were collected, listed and analyzed. The merits and demerits between conventional printed electronics and the new direct writing methods were comparatively evaluated. Important scientific issues and technical strategies to modify the DREAM ink were suggested and potential application areas were proposed. Further, digestions on the impacts of the new technology among energy, health, and environmental sciences were presented. Meanwhile, some practical challenges, such as security, environment-friendly feature, steady usability, package, etc. were summarized. It is expected that the DREAM ink technology will initiate a series of unconventional applications in modern society, and even enter into peoples’ daily life in the near future.

关键词: direct writing of electronics based on alloy and metal (DREAM) ink     direct writing of electronics     printed electronics     liquid metal ink     integrated circuit     consumer electronics     nano liquid metal    

New kind of subarea-parallel scanning mode for laser metal deposition shaping

BIAN Hongyou, LIU Weijun, ZHAO Jibin

《机械工程前沿(英文)》 2007年 第2卷 第4期   页码 417-422 doi: 10.1007/s11465-007-0071-1

摘要: A scanning mode is the key technology in a laser metal deposition shaping (LMDS) fabrication process. On the basis of the analysis of existing scanning modes and their influences on the fabrication efficiency and the quality of parts, some disadvantages of them are pointed out. A new kind of subarea-parallel scanning mode for LMDS based on a subdividing profiled outline into monotonous polygon subareas is presented. First, based on the principle of point visibility, inner loops are eliminated, and simple polygons are subdivided into monotonous polygons with the minimal zones. Second, the parallel scanning paths of all monotonous polygon subareas are finished, which diminishes the length of the scanning line. The practical application shows that the scanning mode can enhance the fabrication efficiency and quality.

关键词: scanning     parallel scanning     practical application     fabrication efficiency     LMDS    

Review of materials used in laser-aided additive manufacturing processes to produce metallic products

Xiaodong NIU, Surinder SINGH, Akhil GARG, Harpreet SINGH, Biranchi PANDA, Xiongbin PENG, Qiujuan ZHANG

《机械工程前沿(英文)》 2019年 第14卷 第3期   页码 282-298 doi: 10.1007/s11465-019-0526-1

摘要: Rapid prototyping (RP) or layered manufacturing (LM) technologies have been extensively used to manufacture prototypes composed mainly of plastics, polymers, paper, and wax due to the short product development time and low costs of these technologies. However, such technologies, with the exception of selective laser melting and sintering, are not used to fabricate metallic products because of the resulting poor life, short cycle, poor surface finish, and low structural integrity of the fabricated parts. The properties endowed by these parts do not match those of functional parts. Therefore, extensive research has been conducted to develop new additive manufacturing (AM) technologies by extending existing RP technologies. Several AM technologies have been developed for the fabrication of metallic objects. These technologies utilize materials, such as Ni-, Al-, and Ti-based alloys and stainless steel powders, to fabricate high-quality functional components. The present work reviews the type of materials used in laser-based AM processes for the manufacture of metallic products. The advantages and disadvantages of processes and different materials are summarized, and future research directions are discussed in the final section. This review can help experts select the ideal type of process or technology for the manufacturing of elements composed of a given alloy or material (Ni, Ti, Al, Pb, and stainless steel).

关键词: direct metal deposition     laser-based manufacturing     rapid manufacturing     selective laser melting     additive manufacturing    

无溶剂气相制备用于可持续分离过程的膜材料 Perspective

赵俊杰, Karen K. Gleason

《工程(英文)》 2020年 第6卷 第12期   页码 1432-1442 doi: 10.1016/j.eng.2020.05.002

摘要:

可用于水净化、碳捕集、生物燃料生产、燃料电池运行以及节能工业分离操作的可持续化工过程亟待发展下一代膜材料。膜的无溶剂制备不仅消除了有机溶剂的潜在环境问题,而且解决了脆弱聚合物基材的膨胀问题。此外,采用无溶剂气相沉积方法可以减少合成微孔材料[如金属有机骨架(MOF)]所需的活化步骤。本文综述了几种真空沉积工艺,包括引发式化学气相沉积(iCVD)、引发式等离子体增强化学气相沉积(iPECVD)、无溶剂气相沉积原位聚合(SLIP)、原子层沉积(ALD) 和分子层沉积(MLD)。这些无溶剂气相沉积方法在制备薄膜复合膜结构中的超薄选择层方面极具优势,而且能够保形地修饰纳米级孔道并精确调节孔径和孔内官能团。所制备的膜在气体分离、 纳滤、海水淡化和水/油分离等方面表现出颇具应用潜力的性能。因此,开发新型膜材料、放大可用于无溶剂气相沉积的高通量反应器将对化学工业产生巨大影响。

关键词: 膜分离     化学气相沉积     原子层沉积     分子层沉积     薄膜     金属有机骨架     聚合物     先进制造    

Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fangxian LI, Cheng ZHOU, Pengfei YANG, Beihan WANG, Jie HU, Jiangxiong WEI, Qijun YU

《结构与土木工程前沿(英文)》 2019年 第13卷 第6期   页码 1405-1414 doi: 10.1007/s11709-019-0564-0

摘要: Fly ash was used as catalytic support for carbon nanotubes (CNTs) growth by chemical vapor deposition (CVD) due to having ideal compositions (SiO , Al O , and Fe O ). In this paper, CNTs were synthesized on Ni catalyst/fly ash substrate using CVD method. The influence of parameters (e.g., reaction temperature and gas flow rate) on the carbon yield and structure of the resulting CNTs was on the carbon yield and structure of the resulting CNTs was investigated by thermo-gravimetric analyses, Scanning electron microscopy, and Raman spectroscopy analysis. The results indicated that the growth temperature controlling had a significant effect on the diameter of CNTs. And the proper acetylene and hydrogen flow rate would decrease in defect density and increase in yield of as-grown CNTs on fly ash. Finally, the amorphous carbon on the surface of as-grown CNTs were removed by heating in air. Experimental results showed that the hydrophobic of the annealed CNTs was weak due to introducing functional groups to the surface of CNTs.

关键词: carbon nanotubes     fly ash     chemical vapor deposition     parameters     purification    

A Pt-Bi bimetallic nanoparticle catalyst for direct electro-oxidation of formic acid in fuel cells

Shu-Hong LI, Yue ZHAO, Jian CHU, Wen-Wei LI, Han-Qing YU, Gang LIU, Yang-Chao TIAN

《环境科学与工程前沿(英文)》 2013年 第7卷 第3期   页码 388-394 doi: 10.1007/s11783-012-0475-y

摘要: Direct formic acid fuel cells are a promising portable power-generating device, and the development of efficient anodic catalysts is essential for such a fuel cell. In this work Pt-Bi nanoparticles supported on micro-fabricated gold wire array substrate were synthesized using an electrochemical deposition method for formic acid oxidation in fuel cells. The surface morphology and element components of the Pt-Bi/Au nanoparticles were characterized, and the catalytic activities of the three Pt-Bi/Au nanoparticle electrodes with different Pt/Bi ratios for formic acid oxidation were evaluated. It was found that Pt Bi /Au had a much higher catalytic activity than Pt Bi /Au and Pt Bi /Au, and Pt Bi /Au exhibited a current density of 2.7 mA·cm , which was 27-times greater than that of Pt/Au. The electro-catalytic activity of the Pt-Bi/Au electrode for formic acid oxidation increased with the increasing Bi content, suggesting that it would be possible to achieve an efficient formic acid oxidation on the low Pt-loading. Therefore, the Pt-Bi/Au electrode offers a promising catalyst with a high activity for direct oxidation of formic acid in fuel cells.

关键词: catalyst     electrochemical deposition     formic acid oxidation     fuel cell     gold wire array     microfabrication    

Scaling up of cluster beam deposition technology for catalysis application

《化学科学与工程前沿(英文)》 2021年 第15卷 第6期   页码 1360-1379 doi: 10.1007/s11705-021-2101-7

摘要: Many research works have demonstrated that the combination of atomically precise cluster deposition and theoretical calculations is able to address fundamental aspects of size-effects, cluster-support interactions, and reaction mechanisms of cluster materials. Although the wet chemistry method has been widely used to synthesize nanoparticles, the gas-phase synthesis and size-selected strategy was the only method to prepare supported metal clusters with precise numbers of atoms for a long time. However, the low throughput of the physical synthesis method has severely constrained its wider adoption for catalysis applications. In this review, we introduce the latest progress on three types of cluster source which have the most promising potential for scale-up, including sputtering gas aggregation source, pulsed microplasma cluster source, and matrix assembly cluster source. While the sputtering gas aggregation source is leading ahead with a production rate of ~20 mg·h–1, the pulsed microplasma source has the smallest physical dimensions which makes it possible to compact multiple such devices into a small volume for multiplied production rate. The matrix assembly source has the shortest development history, but already show an impressive deposition rate of ~10 mg·h–1. At the end of the review, the possible routes for further throughput scale-up are envisaged.

关键词: nanoparticle     cluster     cluster beam deposition     magnetron sputtering     heterogeneous catalysis    

Effect of carbon deposition over carbonaceous catalysts on CH

Yongfa ZHANG, Meng ZHANG, Guojie ZHANG, Huirong ZHANG

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 481-485 doi: 10.1007/s11705-010-0523-8

摘要: An investigation was made using a continuous fixed bed reactor to understand the influence of carbon deposition obtained under different conditions on CH -CO reforming. Thermogravimetry (TG) and X-ray diffraction (XRD) were employed to study the characteristics of carbon deposition. It was found that the carbonaceous catalyst is an efficient catalyst in methane decomposition and CH -CO reforming. The trend of methane decomposition at lower temperatures is similar to that at higher temperatures. The methane conversion is high during the initial of stage of the reaction, and then decays to a relatively fixed value after about 30 min. With temperature increase, the methane decomposition rate increases quickly. The reaction temperature has significant influence on methane decomposition, whereas the carbon deposition does not affect methane decomposition significantly. Different types of carbon deposition were formed at different methane decomposition reaction temperatures. The carbon deposition Type I generated at 900°C has a minor effect on CH -CO reforming and it easily reacts with carbon dioxide, but the carbon deposition Type II generated at 1000°C and 1100°C clearly inhibits CH -CO reforming and it is difficult to react with carbon dioxide. The results of XRD showed that some graphite structures were found in carbon deposition Type II.

关键词: carbon deposition     carbonaceous catalyst     CH4-CO2 reforming    

Influence mechanism of dynamic and static liquid bridge forces on particle deposition behaviors in solar

Xueqing LIU, Xiaodong ZHAO, Luyi LU, Jianlan LI

《能源前沿(英文)》 2021年 第15卷 第2期   页码 499-512 doi: 10.1007/s11708-021-0742-3

摘要: Solar energy is one of the most promising forms of renewable energy for solving the energy crisis and environmental problems. Dust deposition on photovoltaic mirrors has a serious negative impact on the photoelectric conversion efficiency of solar power stations. In this paper, the influence mechanism of the dynamic and static liquid bridge forces on particle deposition behaviors on solar photovoltaic mirrors is investigated. In addition, the expression and physical meaning of the particle critical separation velocity are proposed. The research results show that the static liquid bridge force can be the primary deposition force causing dust particles to adhere to photovoltaic mirrors. However, the dynamic liquid bridge force can act as a resistance force for the particle motion process and even make dust particles roll along and finally stay on the mirror. The contact force is the primary separation force that causes dust particles to flow away from the mirror. Whether dust particles adhere to the mirror depends on the relative size of the deposition and separating forces. The particle critical separation velocity describes the relative size of the collision-rebound effect and mirror adhesion effect and is expressed in Eq. (16). These research findings can provide theoretical guidance for mirror cleaning methods in the operation process of photovoltaic mirrors.

关键词: dust deposition     discrete element method (DEM)     photovoltaic mirrors     solar energy    

ECOLOGICAL EFFECTS OF NITROGEN DEPOSITION ON URBAN FORESTS: AN OVERVIEW

《农业科学与工程前沿(英文)》 2022年 第9卷 第3期   页码 445-456 doi: 10.15302/J-FASE-2021429

摘要:

● Patterns and effects of N deposition on urban forests are reviewed.

关键词: biodiversity     carbon sequestration     nitrogen deposition     nutrient imbalance     soil acidification     urban forest    

Fault simulation of boiler heating surface ash deposition in a power plant system

Weiwei ZHANG, Huisheng ZHANG, Ming SU

《能源前沿(英文)》 2011年 第5卷 第4期   页码 435-443 doi: 10.1007/s11708-011-0162-x

摘要: The simulation model of a power generation system was developed based on EASY5 simulation platform. The performances of the power plant under the conditions of the furnace slagging and ash deposition of the heating surfaces in the boiler were simulated. The results show that the simulation model can reasonably reflect the characteristics of the power plant when each component is under fault conditions. Through fault simulation, the change of the performance parameters can be obtained, which can be used in fault diagnosis system as the diagnosis criterion for expert system.

关键词: boiler     slagging     ash deposition     fault simulation    

Influence of phosphate on deposition and detachment of TiO

Zhan Wang, Chongyang Shen, Yichun Du, Yulong Zhang, Baoguo Li

《环境科学与工程前沿(英文)》 2019年 第13卷 第5期 doi: 10.1007/s11783-019-1163-y

摘要: We examined influence of phosphate on transport of TiO2 NPs in soil. Deposition was reduced at higher pH and by adsorption of phosphate in soil. Release was more for NPs initially deposited at higher pH. Release was more for NPs initially deposited in the presence of phosphate. Surface roughness and charge heterogeneity play a role in the deposition/ release. The widespread use of TiO2 nanoparticles (NPs) makes inevitable their release into the soil. Phosphate is also widespread within soil, and is likely copresent with TiO2 NPs. However, the influence of phosphate on deposition/release— and thereby on transport— of TiO2 NPs in soil is yet to be elucidated. In this study we conducted saturated column experiments to systematically examine the transport of TiO2 NPs in soil amended with phosphate at different ionic strengths (ISs) (1, 10, 100 mmol/L NaCl) and pHs (4 and 9). Results show that the deposition of TiO2 NPs decreased with decreasing IS, increasing pH, and when soil absorbed phosphate. These observations are qualitatively in agreement with Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energy calculations, because the repulsive energy barrier is larger and secondary minimum depth is smaller at a lower IS, higher pH, and in the presence of phosphate. Accordingly, both primary- and secondary-minimum deposition were inhibited. Interestingly, although the deposition was less at higher pH and in the presence of phosphate, the subsequent spontaneous detachment and detachment by reduction of solution IS in these cases were greater. In addition, the presence of phosphate in the solution can cause a small quantity of attached TiO2 NPs to detach, even without perturbations of physical and chemical conditions. Our study was the first to investigate the influence of phosphate on detachment of TiO2 NPs and the results have important implication for accurate prediction of fate and transport of TiO2 NPs in subsurface environments.

关键词: Phosphate     TiO2 nanoparticles     Transport     Soil     Deposition     Detachment    

RESEARCH PROGRESS ON THE IMPACT OF NITROGEN DEPOSITION ON GLOBAL GRASSLANDS

《农业科学与工程前沿(英文)》 2022年 第9卷 第3期   页码 425-444 doi: 10.15302/J-FASE-2022457

摘要:

● Grasslands in many regions of the world have been impacted by atmospheric nitrogen deposition.

关键词: Acidification     biomass production     critical load     eutrophication     species composition     species richness    

Additive direct-write microfabrication for MEMS: A review

Kwok Siong TEH

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 490-509 doi: 10.1007/s11465-017-0484-4

摘要:

Direct-write additive manufacturing refers to a rich and growing repertoire of well-established fabrication techniques that builds solid objects directly from computer-generated solid models without elaborate intermediate fabrication steps. At the macroscale, direct-write techniques such as stereolithography, selective laser sintering, fused deposition modeling ink-jet printing, and laminated object manufacturing have significantly reduced concept-to-product lead time, enabled complex geometries, and importantly, has led to the renaissance in fabrication known as the . The technological premises of all direct-write additive manufacturing are identical—converting computer generated three-dimensional models into layers of two-dimensional planes or slices, which are then reconstructed sequentially into three-dimensional solid objects in a layer-by-layer format. The key differences between the various additive manufacturing techniques are the means of creating the finished layers and the ancillary processes that accompany them. While still at its infancy, direct-write additive manufacturing techniques at the microscale have the potential to significantly lower the barrier-of-entry—in terms of cost, time and training—for the prototyping and fabrication of MEMS parts that have larger dimensions, high aspect ratios, and complex shapes. In recent years, significant advancements in materials chemistry, laser technology, heat and fluid modeling, and control systems have enabled additive manufacturing to achieve higher resolutions at the micrometer and nanometer length scales to be a viable technology for MEMS fabrication. Compared to traditional MEMS processes that rely heavily on expensive equipment and time-consuming steps, direct-write additive manufacturing techniques allow for rapid design-to-prototype realization by limiting or circumventing the need for cleanrooms, photolithography and extensive training. With current direct-write additive manufacturing technologies, it is possible to fabricate unsophisticated micrometer scale structures at adequate resolutions and precisions using materials that range from polymers, metals, ceramics, to composites. In both academia and industry, direct-write additive manufacturing offers extraordinary promises to revolutionize research and development in microfabrication and MEMS technologies. Importantly, direct-write additive manufacturing could appreciably augment current MEMS fabrication technologies, enable faster design-to-product cycle, empower new paradigms in MEMS designs, and critically, encourage wider participation in MEMS research at institutions or for individuals with limited or no access to cleanroom facilities. This article aims to provide a limited review of the current landscape of direct-write additive manufacturing techniques that are potentially applicable for MEMS microfabrication.

关键词: direct-write     additive manufacturing     microfabrication     MEMS    

标题 作者 时间 类型 操作

Metal-based direct hydrogen generation as unconventional high density energy

Shuo XU, Jing LIU

期刊论文

Direct writing of electronics based on alloy and metal (DREAM) ink: A newly emerging area and its impact

Qin ZHANG, Yi ZHENG, Jing LIU

期刊论文

New kind of subarea-parallel scanning mode for laser metal deposition shaping

BIAN Hongyou, LIU Weijun, ZHAO Jibin

期刊论文

Review of materials used in laser-aided additive manufacturing processes to produce metallic products

Xiaodong NIU, Surinder SINGH, Akhil GARG, Harpreet SINGH, Biranchi PANDA, Xiongbin PENG, Qiujuan ZHANG

期刊论文

无溶剂气相制备用于可持续分离过程的膜材料

赵俊杰, Karen K. Gleason

期刊论文

Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fangxian LI, Cheng ZHOU, Pengfei YANG, Beihan WANG, Jie HU, Jiangxiong WEI, Qijun YU

期刊论文

A Pt-Bi bimetallic nanoparticle catalyst for direct electro-oxidation of formic acid in fuel cells

Shu-Hong LI, Yue ZHAO, Jian CHU, Wen-Wei LI, Han-Qing YU, Gang LIU, Yang-Chao TIAN

期刊论文

Scaling up of cluster beam deposition technology for catalysis application

期刊论文

Effect of carbon deposition over carbonaceous catalysts on CH

Yongfa ZHANG, Meng ZHANG, Guojie ZHANG, Huirong ZHANG

期刊论文

Influence mechanism of dynamic and static liquid bridge forces on particle deposition behaviors in solar

Xueqing LIU, Xiaodong ZHAO, Luyi LU, Jianlan LI

期刊论文

ECOLOGICAL EFFECTS OF NITROGEN DEPOSITION ON URBAN FORESTS: AN OVERVIEW

期刊论文

Fault simulation of boiler heating surface ash deposition in a power plant system

Weiwei ZHANG, Huisheng ZHANG, Ming SU

期刊论文

Influence of phosphate on deposition and detachment of TiO

Zhan Wang, Chongyang Shen, Yichun Du, Yulong Zhang, Baoguo Li

期刊论文

RESEARCH PROGRESS ON THE IMPACT OF NITROGEN DEPOSITION ON GLOBAL GRASSLANDS

期刊论文

Additive direct-write microfabrication for MEMS: A review

Kwok Siong TEH

期刊论文