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improved biomass-fired cogeneration system simultaneously using extraction steam, cooling water, and feedwater

《能源前沿(英文)》 2022年 第16卷 第2期   页码 321-335 doi: 10.1007/s11708-021-0741-4

摘要: An advanced cogeneration system based on biomass direct combustion was developed and its feasibility was demonstrated. In place of the traditional single heat source (extraction steam), the extraction steam from the turbine, the cooling water from the plant condenser, and the low-pressure feedwater from the feedwater preheating system were collectively used for producing district heat in the new scheme. Hence, a remarkable energy-saving effect could be achieved, improving the overall efficiency of the cogeneration system. The thermodynamic and economic performance of the novel system was examined when taking a 35 MW biomass-fired cogeneration unit for case study. Once the biomass feed rate and net thermal production remain constant, an increment of 1.36 MW can be expected in the net electric production, because of the recommended upgrading. Consequently, the total system efficiency and effective electrical efficiency augmented by 1.23 and 1.50 percentage points. The inherent mechanism of performance enhancement was investigated from the energy and exergy aspects. The economic study indicates that the dynamic payback period of the retrofitting project is merely 1.20 years, with a net present value of 5796.0 k$. In conclusion, the proposed concept is validated to be advantageous and profitable.

关键词: biomass-fired cogeneration     district heat production system     absorption heat pump     extraction steam     cooling water     low-pressure feedwater    

Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration

《化学科学与工程前沿(英文)》 2022年 第16卷 第5期   页码 699-708 doi: 10.1007/s11705-021-2093-3

摘要: Layer-by-layer assembly is a versatile technique for fabricating nanofiltration membranes, where multiple layers of polyelectrolytes are usually required to achieve reasonable separation performance. In this work, an ionic strength directed self-assembly procedure is described for the preparation of nanofiltration membranes consisting of only a single bilayer of poly(diallyldimethylammoniumchloride) and poly(sodium-4-styrenesulfoate). The influence of background ionic strength as well as membrane substrate properties on the formation of single-bilayer membranes are systematically evaluated. Such a simplified polyelectrolyte deposition procedure results in membranes having outstanding separation performance with permeating flux of 14.2 ± 1.5 L∙m–2∙h–1∙bar–1 and Na2SO4 rejection of 97.1% ± 0.8% under a low applied pressure of 1 bar. These results surpass the ones for conventional multilayered polyelectrolyte membranes. This work encompasses an investigation of ionic strength induced coiling of the polyelectrolyte chains and emphasizes the interplay between-polyelectrolyte chain configuration and substrate pore profile. It thus introduces a new concept on the control of membrane fabrication process toward high performance nanofiltration.

关键词: layer-by-layer self-assembly     single bilayer     nanofiltration membrane     desalination    

Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of

Chao Yang, Wenjun Sun, Xiuwei Ao

《环境科学与工程前沿(英文)》 2019年 第13卷 第2期 doi: 10.1007/s11783-019-1111-x

摘要:

UV can induce damages on mRNA consistently among different genes.

SOS response was more active after UV treatment.

Programmed cell death was not found to be more active after UV treatment.

关键词: UV disinfection     Viability     mRNA     SOS response     Programmed cell death    

Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internalpressure

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

《结构与土木工程前沿(英文)》 2020年 第14卷 第6期   页码 1349-1358 doi: 10.1007/s11709-020-0650-3

摘要: A theoretical solution is aimed to be developed in this research for predicting the failure in internally pressurized composite pressure vessels exposed to low-velocity impact. Both in-plane and out-of-plane failure modes are taken into account simultaneously and thus all components of the stress and strain fields are derived. For this purpose, layer-wise theory is employed in a composite cylinder under internal pressure and low-velocity impact. Obtained stress/strain components are fed into appropriate failure criteria for investigating the occurrence of failure. In case of experiencing any in-plane failure mode, the evolution of damage is modeled using progressive damage modeling in the context of continuum damage mechanics. Namely, mechanical properties of failed ply are degraded and stress analysis is performed on the updated status of the model. In the event of delamination occurrence, the solution is terminated. The obtained results are validated with available experimental observations in open literature. It is observed that the sequence of in-plane failure and delamination varies by increasing the impact energy.

关键词: composite pressure vessel     low-velocity impact     failure     theoretical solution     progressive damage modeling    

Study of the robustness of a low-temperature dual-pressure process for removal of CO

Stefania Moioli, Laura A. Pellegrini, Paolo Vergani, Fabio Brignoli

《化学科学与工程前沿(英文)》 2018年 第12卷 第2期   页码 209-225 doi: 10.1007/s11705-017-1688-1

摘要: The growing use of energy by most of world population and the consequent increasing demand for energy are making unexploited low quality gas reserves interesting from an industrial point of view. To meet the required specifications for a natural gas grid, some compounds need to be removed from the sour stream. Because of the high content of undesired compounds (i.e., CO ) in the stream to be treated, traditional purification processes may be too energy intensive and the overall system may result unprofitable, therefore new technologies are under study. In this work, a new process for the purification of natural gas based on a low temperature distillation has been studied, focusing on the dynamics of the system. The robustness of the process has been studied by dynamic simulation of an industrial-scale plant, with particular regard to the performances when operating conditions are changed. The results show that the process can obtain the methane product with a high purity and avoid the solidification of carbon dioxide.

关键词: CO2 capture     innovative process     cryogenic distillation     dynamic simulation     solid-liquid-vapor equilibrium    

Catalytic ozonation of reactive red X-3B in aqueous solution under low pressure: decolorization and OH

Hong SUN,Min SUN,Yaobin ZHANG,Xie QUAN

《环境科学与工程前沿(英文)》 2015年 第9卷 第4期   页码 591-595 doi: 10.1007/s11783-014-0694-5

摘要: Catalytic ozonation of Reactive Red X-3B in aqueous solution had been carried out in an ozone oxidation reactor where Mn-Fe-ceramic honeycomb was used as the catalysts. The presence of Mn-Fe-ceramic honeycomb catalyst could obviously improve the decoloration efficiency of Reactive Red X-3B and the utilization efficiency of ozone compared to the results from non-catalytic ozonation. Adsorption of Reactive Red X-3B had no obviously influence on the degradation efficiency. Addition of tert-butanol significantly decreased the degradation efficiency, indicating that the degradation of Reactive Red X-3B followed the mechanism of hydroxyl radical (OH·) oxidation. The operating variables such as reaction pressure and ozone supply had a positive influence on the degradation efficiency, mainly attributing to facilitate the ozone decomposition and OH· formation.

关键词: catalytic ozonation     reactive red X-3B     ceramic honeycomb     hydroxyl radical (OH·)    

Spray characteristics of high-pressure swirl injector fueled with alcohol

WANG Xibin, CHEN Wansheng, GAO Jian, JIANG Deming, HUANG Zuohua

《能源前沿(英文)》 2007年 第1卷 第1期   页码 105-112 doi: 10.1007/s11708-007-0012-z

摘要: The spray characteristics of methanol and ethanol with high-pressure swirl injector were explored experimentally and numerically. Experimental results show that the spray characteristics of methanol and ethanol had displayed the same trends as that of gasoline. Under the low back-pressure ambient conditions, the spray behavior exhibited a hollow cone with wide spray angle and initial spray slug at the tip, while the spray presented a solid cone in the case of high back-pressure. Vortexes in the opposite direction existed in the rear part of the spray under low back-pressure ambient conditions while the vortexes formed in the middle part under high back-pressure ambient conditions. Experiments also showed that methanol had the largest cone angle, while ethanol and gasoline presented almost the same cone angle. Simulation results indicated that methanol and ethanol had a slightly larger Sauter mean diameter (SMD) than that of gasoline with swirl injector. The SMD profile of methanol coincided well with that of ethanol under low back-pressure ambient conditions, but displayed a slightly larger value under high back-pressure due to fuel evaporation. Numerical simulation could successfully demonstrate the spray characteristics of high-pressure swirl injector for methanol and ethanol fuels.

关键词: low back-pressure     diameter     initial spray     hollow     middle    

Novel technologies for the lost foam casting process

Wenming JIANG, Zitian FAN

《机械工程前沿(英文)》 2018年 第13卷 第1期   页码 37-47 doi: 10.1007/s11465-018-0473-2

摘要:

Lost foam casting (LFC) is a green precision casting process categorized as a near net forming technology. Yet, despite its popularity, it still suffers from some technological problems, such as poor filling ability of the castings, coarse and non-dense microstructure, low mechanical properties for the Al and Mg LFC processes, and defective carburization for the low carbon steel LFC process. These drawbacks restrict the development and widespread application of the LFC process. To solve these problems, the present study developed several novel LFC technologies, namely, LFC technologies under vacuum and low pressure, vibration solidification, and pressure solidification conditions; expendable shell casting techno- logy; and preparation technology of bimetallic castings based on the LFC process. The results showed that the LFC under vacuum and low pressure evidently improved the filling ability and solved the oxidization problem of the alloys, which is suitable for producing complex and thin-wall castings. The vibration and pressure solidifications increased the compactness of the castings and refined the microstructure, significantly improving the mechanical properties of the castings. The expendable shell casting technology could solve the pore, carburization, and inclusion defects of the traditional LFC method, obtaining castings with acceptable surface quality. Moreover, the Al/Mg and Al/Al bimetallic castings with acceptable metallurgical bonding were successfully fabricated using the LFC process. These proposed novel LFC technologies can solve the current technological issues and promote the technological progress of the LFC process.

关键词: LFC under vacuum and low pressure     vibration solidification     pressure solidification     expendable shell casting     bimetallic castings    

Separation of

Wei Hou, Qingjun Zhang, Aiwu Zeng

《化学科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 1169-1184 doi: 10.1007/s11705-020-2018-6

摘要: In this study, vapor recompression and heat integration assisted distillation arrangements with either the low or high pressure in the reflux drum are proposed to reduce and/or eliminate the application of the costly refrigerant for the separation of -heptane and isobutanol mixture. The high-pressure arrangement with vapor recompression and heat integration is the most attractive among these four intensified configurations since it can reduce total annual cost by 18.10%, CO emissions by 75.01% based on natural gas (78.78% based on heavy oil fuel), and second-law efficiency by 61.20% compared to a conventional refrigerated distillation system. Furthermore, exergy destruction in each component is calculated for the heat integration configurations and is shown in pie diagrams. The results demonstrate that the high-pressure configuration presents unique advantages in terms of thermodynamic efficiency compared to the low-pressure case. In addition, dynamic control investigation is performed for the economically efficient arrangement and good product compositions are well controlled through a dual-point temperature control strategy with almost negligible product offsets and quick process responses when addressing 20% step changes in production rate and feed composition. Note that there are no composition measurement loops in our developed control schemes.

关键词: n-heptane/isobutanol     vapor recompression     heat integration     low and/or high-pressure options    

Experimental study of wind loads on gable roofs of low-rise buildings with overhangs

Peng HUANG, Ling TAO, Ming GU, Yong QUAN

《结构与土木工程前沿(英文)》 2018年 第12卷 第3期   页码 300-317 doi: 10.1007/s11709-018-0449-7

摘要:

Gable roofs with overhangs (eaves) are the common constructions of low-rise buildings on the southeastern coast of China, and they were vulnerable to typhoons from experience. The wind pressure distributions on gable roofs of low-rise buildings are investigated by a series of wind tunnel tests which consist of 99 test cases with various roof pitches, height-depth ratios and width-depth ratios. The block pressure coefficients and worst negative (block) pressure coefficients on different roof regions of low-rise buildings are proposed for the main structure and building envelope, respectively. The effects of roof pitch, height-depth ratio, and width-depth ratio on the pressure coefficients of each region are analyzed in detail. In addition, the pressure coefficients on the roofs for the main structure and building envelope are fitted according to roof pitch, height-depth ratio and width-depth ratio of the low-rise building. Meanwhile, the rationality of the fitting formulas is verified by comparing the fitting results with the codes of different countries. Lastly, the block pressure coefficients and worst negative pressure coefficients are recommended to guide the design of low-rise buildings in typhoon area and act as references for the future’s modification of wind load codes.

关键词: low-rise building     gable roof     wind loads     wind tunnel test     block pressure coefficient     load code    

A prototype online database-enabled design framework for wind analysis/design of low-rise buildings

Dae Kun KWON,Ahsan KAREEM,Deepak KUMAR,Yukio TAMURA

《结构与土木工程前沿(英文)》 2016年 第10卷 第1期   页码 121-130 doi: 10.1007/s11709-015-0329-3

摘要: This study presents a development of an advanced cyberbased database-enabled design module for low-rise buildings (DEDM-LR) which provides estimation of the wind-induced responses for main wind force resisting frames by making direct use of pressure time histories measured at a large number of pressure taps over a suite of building models. These responses may be considered in lieu of code-specified load effects in which the overall accuracy may be influenced by the inherent simplifications in codes. In addition, this new automated approach is particularly attractive and advantageous as it allows a web-based online analysis/design via intuitive user-friendly interfaces for both the input and output in terms of familiar web-style forms that are nowadays very common in most of web-based services. Presently, the DEDM-LR hosts an aerodynamic database developed by the Tokyo Polytechnic University (TPU), Japan for a variety of building configurations like flat, gable, and hip roofs under suburban terrain flow condition with immediate application to other databases. The paper shows the efficacy and validity of the DEDM-LR by walking through its details and examples on selected gable-roofed buildings. The architecture of DEDM-LR platform offers the ability to pool resources by hosting other databases that may become available in the near future.

关键词: wind loads     low-rise building     pressure measurement     aerodynamics     building design     structural response     building codes     information technology (IT)    

Piezoresistive pressure sensor with high sensitivity for medical application using peninsula-island structure

Tingzhong XU, Hongyan WANG, Yong XIA, Zhiming ZHAO, Mimi HUANG, Jiuhong WANG, Libo ZHAO, Yulong ZHAO, Zhuangde JIANG

《机械工程前沿(英文)》 2017年 第12卷 第4期   页码 546-553 doi: 10.1007/s11465-017-0447-9

摘要:

A novel micro-electromechanical systems piezoresistive pressure sensor with a diagonally positioned peninsula-island structure has high sensitivity for ultra-low-pressure measurement. The pressure sensor was designed with a working range of 0–500 Pa and had a high sensitivity of 0.06 mV·V−1·Pa−1. The trade-off between high sensitivity and linearity was alleviated. Moreover, the influence of the installation angle on the sensing chip output was analyzed, and an application experiment of the sensor was conducted using the built pipettor test platform. Findings indicated that the proposed pressure sensor had sufficient resolution ability and accuracy to detect the pressure variation in the pipettor chamber. Therefore, the proposed pressure sensor has strong potential for medical equipment application.

关键词: MEMS     low pressure sensor     peninsula-island     ultra-high sensitivity     medical application    

Experiments on the effect of the pressure on the mineral transformation of coal ash under the different

Nijie JING, Qinhui WANG, Zhongyang LUO, Tao JIE, Xiaomin LI, Kefa CEN

《化学科学与工程前沿(英文)》 2010年 第4卷 第4期   页码 394-399 doi: 10.1007/s11705-010-0505-x

摘要: This paper investigated the effect of the pressures, reaction atmospheres and coal ash species on the ash fusibility with high-pressure thermogravimetric analysis (PTGA) apparatus and X-ray diffraction (XRD) analysis. Each specimen analyzed by XRD was observed for the mineral conversion and formation of new minerals with the pressures under different atmospheres. These results indicate that the pressure restrains the transformation and decomposition of minerals. Many low-temperature minerals are still present under the elevated pressure. The different reaction atmospheres have different effects on the formation of coal ash minerals. Under the N atmosphere, the present microcline may decrease the melting temperature of coal ash. And later, it transforms into sanidine at high pressure; thus, the melting temperature of coal ash may increase. Under the CO atmosphere, the minerals such as microcline, lomonitite, geothite and illite are still present with the increase in pressure; this may reduce the melting temperature. While under the H O atmosphere, there are magnetite and anorthoclase, which may produce the low-temperature eutectics decreasing the melting temperature. The coal ash abundance in basic oxides or higher SiO , Fe O , K O and Na O has lower melting temperature. While the ash sample with more SiO and Al O and less Fe O and basic oxides may lead to higher melting temperature.

关键词: ash fusibility     XRD analysis     PTGA     low-temperature eutectic    

鄂尔多斯盆地特低渗透砂岩储层裂缝压力敏感性及其开发意义

曾联波,史成恩,王永康,李书恒,万晓龙,崔攀峰

《中国工程科学》 2007年 第9卷 第11期   页码 35-38

摘要:

为了分析特低渗透砂岩储层高角度裂缝的压力敏感性特征,对鄂尔多斯盆地陇东地区延长组特低渗透砂岩储层基质岩样、含天然裂缝岩样和含人造裂缝岩样进行了对比实验。实验结果表明,特低渗透砂岩储层裂缝的压力敏感性十分明显,在无裂缝时基质岩块为中等程度敏感性,含裂缝时为强压力敏感性。裂缝的开度越大,渗透率越高,其压力敏感性越强,裂缝渗透率的恢复程度越小。裂缝的压力敏感性特征对特低渗透砂岩油藏开发具有十分重要的意义。

关键词: 裂缝     压力敏感性     开发意义     特低渗透砂岩储层     鄂尔多斯盆地    

低高宽比矩形微通道中流动沸腾的压降特性

张炳雷,徐进良,肖泽军

《中国工程科学》 2007年 第9卷 第12期   页码 86-93

摘要: 以甲醇为工质,在不同进口温度、质量流率、热流密度和倾角下,对低高宽比矩形微通道中流动沸腾压降特性进行了研究,并分别采用均相模型和分相模型对通道压降进行了计算。通过对比实验结果与计算结果发现,均相模型中两相平均粘度的计算应当采用Dukler公式,用其他计算式时误差较大;利用LockhartMartinelli关系式进行的分相模型计算发现,现有C值计算公式,如Chisholm,Lee and Lee,Mishima及Qu and Mudawar等,都不能用于预测该实验中低高宽比微通道的两相压降。实验发现当通

关键词: 压降特性;均相模型;分相模型;微通道;流动沸腾    

标题 作者 时间 类型 操作

improved biomass-fired cogeneration system simultaneously using extraction steam, cooling water, and feedwater

期刊论文

Ionic strength directed self-assembled polyelectrolyte single-bilayer membrane for low-pressure nanofiltration

期刊论文

Using mRNA to investigate the effect of low-pressure ultraviolet disinfection on the viability of

Chao Yang, Wenjun Sun, Xiuwei Ao

期刊论文

Theoretical study of failure in composite pressure vessels subjected to low-velocity impact and internalpressure

Roham RAFIEE, Hossein RASHEDI, Shiva REZAEE

期刊论文

Study of the robustness of a low-temperature dual-pressure process for removal of CO

Stefania Moioli, Laura A. Pellegrini, Paolo Vergani, Fabio Brignoli

期刊论文

Catalytic ozonation of reactive red X-3B in aqueous solution under low pressure: decolorization and OH

Hong SUN,Min SUN,Yaobin ZHANG,Xie QUAN

期刊论文

Spray characteristics of high-pressure swirl injector fueled with alcohol

WANG Xibin, CHEN Wansheng, GAO Jian, JIANG Deming, HUANG Zuohua

期刊论文

Novel technologies for the lost foam casting process

Wenming JIANG, Zitian FAN

期刊论文

Separation of

Wei Hou, Qingjun Zhang, Aiwu Zeng

期刊论文

Experimental study of wind loads on gable roofs of low-rise buildings with overhangs

Peng HUANG, Ling TAO, Ming GU, Yong QUAN

期刊论文

A prototype online database-enabled design framework for wind analysis/design of low-rise buildings

Dae Kun KWON,Ahsan KAREEM,Deepak KUMAR,Yukio TAMURA

期刊论文

Piezoresistive pressure sensor with high sensitivity for medical application using peninsula-island structure

Tingzhong XU, Hongyan WANG, Yong XIA, Zhiming ZHAO, Mimi HUANG, Jiuhong WANG, Libo ZHAO, Yulong ZHAO, Zhuangde JIANG

期刊论文

Experiments on the effect of the pressure on the mineral transformation of coal ash under the different

Nijie JING, Qinhui WANG, Zhongyang LUO, Tao JIE, Xiaomin LI, Kefa CEN

期刊论文

鄂尔多斯盆地特低渗透砂岩储层裂缝压力敏感性及其开发意义

曾联波,史成恩,王永康,李书恒,万晓龙,崔攀峰

期刊论文

低高宽比矩形微通道中流动沸腾的压降特性

张炳雷,徐进良,肖泽军

期刊论文