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Combined use of fly ash and silica to prevent the long-term strength retrogression of oil well cement set and cured at HPHT conditions
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作者 Guo-Dong Cheng Xue-Yu Pang +4 位作者 Jin-Sheng Sun Zheng-Song Qiu Chuang-Chuang Wang Jian-Kun Qin Ning Li 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期1122-1134,共13页
The long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells, which is a major obstacle for deep petroleum and geothermal energy... The long-term strength retrogression of silica-enriched oil well cement poses a significant threat to wellbore integrity in deep and ultra-deep wells, which is a major obstacle for deep petroleum and geothermal energy development. Previous attempts to address this problem has been unsatisfactory because they can only reduce the strength decline rate. This study presents a new solution to this problem by incorporating fly ash to the traditional silica-cement systems. The influences of fly ash and silica on the strength retrogression behavior of oil well cement systems directly set and cured under the condition of 200°C and 50 MPa are investigated. Test results indicate that the slurries containing only silica or fly ash experience severe strength retrogression from 2 to 30 d curing, while the slurries containing both fly ash and silica experience strength enhancement from 2 to 90 d. The strength test results are corroborated by further evidences from permeability tests as well as microstructure analysis of set cement. Composition of set cement evaluated by quantitative X-ray diffraction analyses with partial or no known crystal structure(PONKCS) method and thermogravimetry analyses revealed that the conversion of amorphous C-(A)-S-H to crystalline phases is the primary cause of long-term strength retrogression.The addition of fly ash can reduce the initial amount of C-(A)-S-H in the set cement, and its combined use with silica can prevent the crystallization of C-(A)-S-H, which is believed to be the working mechanism of this new admixture in improving long-term strength stability of oil well cement systems. 展开更多
关键词 Fly ash Long-term strength retrogression High temperature Quantitative x-ray diffraction(QXRD) Partial or no known crystal structure(PONKCS)
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Behavior of Fly Ash at Different Mix Ratios with Plastic Recycled Polymers
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作者 Tushar Vasant Salunkhe 《Journal of Civil Engineering and Architecture》 2024年第9期438-444,共7页
Fly ash is a waste produced from burning of coals in thermal power stations. The staggering increase in the production of fly ash and its disposal in an environment friendly manner is increasingly becoming a matter of... Fly ash is a waste produced from burning of coals in thermal power stations. The staggering increase in the production of fly ash and its disposal in an environment friendly manner is increasingly becoming a matter of global concern. Many efforts have been made to use the fly ash in various geotechnical applications viz. embankment, roadway, railway, backfill material. In this study, PRPs (plastic recycled polymers) were mixed with fly ash at different mix ratios so as to inspect its influence on the geotechnical properties of fly ash. In this regard, the laboratory study includes Atterberg limits, compaction characteristics, unconfined compressive strength, direct shear test, Triaxial shear test and X-ray fluorescence test. Tests were carried out on only fly ash and treated fly ash with PRPs. Results indicate increase in MDD (maximum dry density) and also in shear parameters of the fly ash with inclusion of PRPs. 展开更多
关键词 Fly ash PRPs x-ray fluorescence shear parameters
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Studying a kind of portable ultra-bright microfocus x-ray source
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作者 王凯歌 王雷 牛憨笨 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第5期1807-1813,共7页
This paper studies the properties of a kind of portable ultra-bright microfocus x-ray source with the Monte-Carlo method in detail. The new x-ray source consists of an electron-emission system, an electrostatic focusi... This paper studies the properties of a kind of portable ultra-bright microfocus x-ray source with the Monte-Carlo method in detail. The new x-ray source consists of an electron-emission system, an electrostatic focusing system and a metal target. A crystal Lanthanum Hexaboride cathode, a Wehnelt grid and an extracted electrode compose the triode electrode electron-gun system. Two equal radius cylinder electrodes form the focusing system. The key factors determining the focus properties of the electron beam such as the ratio Dw/H, grid bias Vg, and the properties of the extracted electrode arc numerically studied. The calculated results reveal that when Dw/H, Vg, the length of the extracted electrode, and the distance between the grid and the extracted electrode equals 5, q).6 kV, 10 mm, and 8 mm respectively, the electron beam focal spot can be concentrated down to 9 μm in radius and a reasonable focal length about 72.5 mm can be achieved, at the same time, the cathode emission currents can be as high as 30 mA. 展开更多
关键词 microfocus x-ray source high brightness micro-focal spot Monte-Carlo method
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Residual Stresses in Resistance Spot Welded AZ61 Mg Alloy
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作者 Davood Afshari Soheil Mirzaahamdi Zuheir Barsoum 《Computer Modeling in Engineering & Sciences》 SCIE EI 2019年第2期275-290,共16页
The use of magnesium alloys has been rapidly increased due to their ability to maintain high strengths at light weights.However weldability of steels and aluminum alloys by using resistance spot weld(RSW)process is a ... The use of magnesium alloys has been rapidly increased due to their ability to maintain high strengths at light weights.However weldability of steels and aluminum alloys by using resistance spot weld(RSW)process is a major issue,because it cannot be directly utilized for magnesium alloys.In this study,a structural-thermal-electrical finite element(FE)model has been developed to predict the distribution of residual stresses in RSW AZ61 magnesium alloy.Thermophysical and thermomechanical properties of AZ61 magnesium alloy have been experimentally determined,and have been used in FE model to increase the accuracy of the model.X-ray diffraction(XRD)technique has been utilized to measure the residual stresses in welded samples,and its results have been used to validate the FE model.Comparison study shows that the results obtained by using FE model have a good agreement with the experimental XRD data.In specific,the results show that the maximum tensile residual stress occurs at the weld center while decreases towards the nugget edge.In addition,the effects of welding parameters such as electrical current,welding time,and electrode force have been investigated on the maximum tensile residual stress.The results show that the tensile residual stress in welded joints rises by increasing the electrical current;however,it declines by prolonging the welding time as well as increasing the electrode force. 展开更多
关键词 RESISTANCE spot WELD AZ61 mg alloy residual stresses finite element model x-ray diffraction.
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X-Pinches as Broadband Sources of X-Rays for Radiography
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作者 Tatiana Shelkovenko Sergey Pikuz David Hammer 《Journal of Biomedical Science and Engineering》 2015年第11期747-755,共9页
Two methods of using the X-pinch as a source of X-ray radiation for radiography of biological objects are presented. X-pinches are found to be a very flexible method for generation of radiation over a wide spectral ra... Two methods of using the X-pinch as a source of X-ray radiation for radiography of biological objects are presented. X-pinches are found to be a very flexible method for generation of radiation over a wide spectral range and provide a high spatial and temporal resolution. 展开更多
关键词 X-PINCH x-ray HOT spot Electron Beam Point-Projection RADIOGRAPHY Biological Object
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广东烟叶主要真菌病害无公害化学防治药剂筛选试验 被引量:6
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作者 蒲小明 沈会芳 +5 位作者 陈永明 张景欣 邱妙文 孙大元 张雷斌 林壁润 《广东农业科学》 CAS 2016年第11期97-102,共6页
烟草黑胫病和赤星病已成为广东烟叶生产的重要真菌病害,开展其无公害化学药剂筛选和应用研究势在必行。以烟草黑胫病菌和赤星病菌为研究对象,室内毒力测定结果表明:烯酰吗啉和氟吡菌胺的对烟草黑胫病菌的毒力最高(EC50分别为0.56μg/m L... 烟草黑胫病和赤星病已成为广东烟叶生产的重要真菌病害,开展其无公害化学药剂筛选和应用研究势在必行。以烟草黑胫病菌和赤星病菌为研究对象,室内毒力测定结果表明:烯酰吗啉和氟吡菌胺的对烟草黑胫病菌的毒力最高(EC50分别为0.56μg/m L和0.25μg/m L),苯酰菌胺对烟草黑胫病菌的毒力次之(EC50为1.14μg/m L);咪鲜胺对烟草赤星病菌的毒力最高(EC50为0.26μg/m L),75%肟菌·戊唑醇水分散粒剂对烟草赤星病菌的毒力较高(EC50为2.66μg/m L)。田间试验结果表明:处理后15 d,推荐药剂50%烯酰吗啉可湿性粉剂1 500倍和80%苯酰菌胺可溶性粉剂2 500倍轮换施用防治烟草黑胫病的效果为87.23%;推荐药剂45%咪鲜胺水乳剂2 000倍和75%肟菌·戊唑醇水分散粒剂2 500倍轮换施用对烟草赤星病的效果为82.53%;均显著高于对照药剂的防治效果。研究结果为烟叶真菌病害化学防控提供了技术指导,促进了烟叶绿色安全生产,保证了烟叶产量和品质。 展开更多
关键词 烟草黑胫病 烟草赤星病 化学防治 室内毒力 药效试验
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Technological and Environmental Behavior of Coal Fly Ash in Lime-Based Materials 被引量:1
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作者 Mamoudou Sall Gora Dieye +4 位作者 Alassane Traoré Prince Momar Gueye Saliou Diouf Abdou Ciss Wade Djibril Diop 《Geomaterials》 2022年第2期15-29,共15页
Coal fly ash is considered an industrial by-product derived from coal combustion in thermal power plant. It is one of the most complex anthropogenic materials. Its improper disposal has become an environmental concern... Coal fly ash is considered an industrial by-product derived from coal combustion in thermal power plant. It is one of the most complex anthropogenic materials. Its improper disposal has become an environmental concern and resulted in a waste of recoverable resources. The aim of this paper is to study the physico-chemical characteristics of binders based on coal fly ash and lime in order to develop an eco-cement. The various characterization tests carried out are X-ray fluorescence, X-ray diffraction, compressive strengths, thermophysical properties and setting time. X-ray fluorescence and X-ray diffraction were used to determine the chemical composition and phases of fly ash, lime and binders. This allowed us to see that the chemical composition of fly ash is similar to that of cement. Compressive strengths of mortars containing 20%, 40%, 60% and 80% of fly ash have shown that fly ash has a long-term positive effect which might be related to a pozzolanic activity. The L<sub>3</sub> binder consisting of 60% of coal fly ash and 40% lime has a higher compressive strength than the others. The binder setting start time is greater than that of cement but shorter than that of lime. The study of the thermophysical properties of the L<sub>3</sub> binder shows that it has a higher thermal resistance than cement mortar. Moreover, it heats up less quickly because of its low effusivity compared to that of the latter. This analysis highlighted the principal characteristics that must be taken into account to use coal fly correctly in lime-based materials. 展开更多
关键词 Coal Fly Ash LIME BINDER x-ray Fluorescence x-ray Diffraction Thermomechanical Behavior
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Spot size diagnostics for flash radiographic X-ray sources at LAPA
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作者 李成刚 李勤 +1 位作者 石金水 邓建军 《Chinese Physics C》 SCIE CAS CSCD 2009年第S2期157-160,共4页
Spot size is one of the parameters to characterize the performance of a radiographic X-ray source. It determines the degree of blurring due to magnification directly. In recent years, a variety of measurement methods ... Spot size is one of the parameters to characterize the performance of a radiographic X-ray source. It determines the degree of blurring due to magnification directly. In recent years, a variety of measurement methods have been used to diagnose X-ray spot size at Laboratory of Accelerator Physics and Application (LAPA). Computer simulations and experiments showed that using a rolled-edge to measure the spot size are more accurate, and the intensity distribution of X-ray source was obtained by a device with a square aperture. Experimental and simulation results on a flash X-ray source at our laboratory are presented and discussed in this paper. In addition, a new method for time resolved diagnostics of X-ray spot size is introduced too. 展开更多
关键词 linear induction accelerator x-ray spot size rolled-edge square aperture time resolved Dragon-I
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Spot size measurement of a flash-radiography source using the pinhole imaging method
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作者 王毅 李勤 +4 位作者 陈楠 程晋明 谢宇彤 刘云龙 龙全红 《Chinese Physics C》 SCIE CAS CSCD 2016年第7期124-128,共5页
The spot size of the X-ray source is a key parameter of a flash-radiography facility, and is usually quoted as an evaluation of the resolving power. The pinhole imaging technique is applied to measure the spot size of... The spot size of the X-ray source is a key parameter of a flash-radiography facility, and is usually quoted as an evaluation of the resolving power. The pinhole imaging technique is applied to measure the spot size of the Dragon-I linear induction accelerator, by which a two-dimensional spatial distribution of the source spot is obtained. Experimental measurements are performed to measure the spot image when the transportation and focusing of the electron beam are tuned by adjusting the currents of solenoids in the downstream section. The spot size of full-width at half maximum and that defined from the spatial frequency at half peak value of the modulation transfer function are calculated and discussed. 展开更多
关键词 spot size x-ray source PINHOLE linear induction accelerator
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Physical and mechanical properties of municipal solid waste incineration residues with cement and coal fly ash using X-ray Computed Tomography scanners
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作者 Toshifumi MUKUNOKI Ta Thi HOAI +2 位作者 Daisuke FUKUSHIMA Teppei KOMIYA Takayuki SHIMAOKA 《Frontiers of Structural and Civil Engineering》 SCIE EI CSCD 2019年第3期640-652,共13页
A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e.,incineration residues) are commonly disposed as landfill.Meanwhile,reclamation of landfill sites to create a new land space after... A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e.,incineration residues) are commonly disposed as landfill.Meanwhile,reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries.The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction.Indeed,physical and mechanical properties of these new materials should be initially examined at the micro scale,which is the primary fundamental for construction at larger scale.This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading.Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect.Nine types of cement solidified incineration residues in term of different curing period (i.e.,7,14,28 days) and coal fly ash addition content (i.e.,0%,9%,18%) were scanned before and after unconfined compression tests.It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content.Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials.Then,it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength. 展开更多
关键词 mechanical property MUNICIPAL solid waste INCINERATION RESIDUES coal FLY ash unconfined compression test image analysis x-ray COMPUTED Tomography scanners
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Mechanism of flue gas simultaneous desulfurization and denitrification using the highly reactive absorbent 被引量:5
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作者 ZHAO Yi SUN Xiaojun +3 位作者 XU Peiyao MA Shuangchen WANG Lidong LIU Feng 《Science China(Technological Sciences)》 SCIE EI CAS 2005年第6期692-705,共14页
Fly ash,industry-grade lime and a few oxidizing manganese compound additive were used to prepare the“Oxygen-riched”highly reactive absorbent for simultaneous desulfurization and denitrification.Experiments of simult... Fly ash,industry-grade lime and a few oxidizing manganese compound additive were used to prepare the“Oxygen-riched”highly reactive absorbent for simultaneous desulfurization and denitrification.Experiments of simultaneous desulfurization and denitrification were carried out using the highly reactive absorbent in the flue gas circulating fluidized bed(CFB)system.Removal efficiencies of 94.5%for SO_(2)and 64.2%for NO were obtained respectively.The scanning electron microscope(SEM)and accessory X-ray energy spectrometer were used to observe micro-properties of the samples,including fly ash,common highly reactive absorbent,“Oxygen-riched”highly reactive absorbent and spent absorbent.The white flake layers were observed in the SEM images about surfaces of the common highly reactive absorbent and“Oxygen-riched”one,and the particle surfaces of the spent absorbent were porous.The content of calcium on surface was higher than that of the average in the highly reactive absorbent.The manganese compound additive dispersed uniformly on the surfaces of the“Oxygen-riched”highly reactive absorbent.There was a sulfur peak in the energy spectra pictures of the spent absorbent.The component of the spent absorbent was analyzed with chemical analysis methods,and the results indicated that more nitrogen species appeared in the absorbent except sulfur species,and SO_(2)and NO were removed by chemical absorption according to the experimental results of X-ray energy spectrometer and the chemical analysis.Sulfate being the main desulfurization products,nitrite was the main denitrification ones during the process,in which NO was oxidized rapidly to NO_(2)and absorbed by the chemical reaction. 展开更多
关键词 highly reactive absorbent fly ash simultaneous desulfurization and denitrification micro-property scanning electron microscope x-ray energy spectra
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