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Correlation between hardness and SEM-EDS characterization of palm oil waste based biocoke
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作者 Asri Gani Erdiwansyah +5 位作者 Hera Desvita Saisa Mahidin Rizalman Mamat Zulhaini Sartika Ratna Eko Sarjono 《Energy Geoscience》 EI 2024年第4期253-266,共14页
This research investigates the relationship between hardness and microstructure obtained through SEM-EDS analysis of palm oil waste-based biocoke.The mechanical qualities and chemical composition of biocoke are being ... This research investigates the relationship between hardness and microstructure obtained through SEM-EDS analysis of palm oil waste-based biocoke.The mechanical qualities and chemical composition of biocoke are being studied concerning the influence of temperature conditions.The manufacturing temperature of biocoke may vary between 150℃ and 190℃.Utilizing SEM-EDS,we were able to characterize the microstructure and analyze the elemental composition,while the Hardness Shore D approach was used for the most complex materials.These results highlight the possibility of optimizing production temperature to produce biocoke with better mechanical performance.They show a positive correlation between biocoke hardness and structured carbon content.At 150℃ and 180℃,respectively,the EFB biocoke reached its maximum hardness level of 62±5.At 190℃,OPM biocoke generated a 60±5 times greater hardness than that of OPM and OPF biocoke.The OPT biocoke sample had the highest porosity with a score of 0.86,or 85.76%.Furthermore,compared to EFB biocoke,OPM and OPF biocokes had a priority of 0.84(84.20%)and 0.83(83.48%),respectively.Biocoke hardness is a quality indicator of physical and chemical qualities;the vital link between biocoke hardness,structural features,and elemental composition supports this idea. 展开更多
关键词 Biocoke Palm oil waste hardness SEM-EDS Processing temperature
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Gravel hardness effect on compaction characteristics of gravelly soil
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作者 SHI Yunfang LI Shengang +1 位作者 JIANG Chen LIU Jinning 《Journal of Mountain Science》 SCIE CSCD 2024年第4期1432-1443,共12页
The compaction characteristics of gravelly soil are affected by gravel hardness.To investigate the evolution and influencing mechanism of different gravel hardness on the compaction characteristics of gravelly soil,he... The compaction characteristics of gravelly soil are affected by gravel hardness.To investigate the evolution and influencing mechanism of different gravel hardness on the compaction characteristics of gravelly soil,heavy compaction tests and crushing tests were conducted on gravelly soils with gravels originated from hard,soft and extremely soft rocks.According to orthogonal experiments and variance analysis,it was found that hardness has a significant impact on the maximum dry density of gravelly soil,followed by gravel content,and lastly,moisture content.For gravel compositions with an average saturated uniaxial compressive strength less than 60 MPa,the order of compacted maximum dry density is soft gravels>hard gravels>extremely soft gravels.Each type of gravelly soil has a threshold for gravel content,with 60%for hard and soft gravels and 50%for extremely soft gravels.Beyond these thresholds,the compacted dry density decreases significantly.There is a certain interaction between hardness,gravel content,and moisture content.Higher hardness increases the influence of gravel content,whereas lower hardness increases the influence of moisture content.Gravelly soils with the coarse aggregate(CA)between 0.7 and 0.8 typically achieve higher dry densities after compaction.In addition,the prediction equations for the particle breakage rate and CA ratio in the Bailey method were proposed to estimate the compaction performance of gravelly soil preliminarily.The results further revealed the compaction mechanism of different gravelly soils and can provide reference for subgrade filling construction. 展开更多
关键词 Gravelly soil hardness Compaction characteristics Crushing characteristics Particle breakage rate Bailey method
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Influence of heat input on microhardness and microstructure across the welding interface between stainless steel and low alloy steel
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作者 ZHU Min 《Baosteel Technical Research》 CAS 2024年第1期14-21,共8页
The welding interface is crucial to the service safety of dissimilar metal weld(DMW)joints between stainless steel(SS)and low alloy(LA)steel.Different status of welding interfaces was prepared by cladding SS consumabl... The welding interface is crucial to the service safety of dissimilar metal weld(DMW)joints between stainless steel(SS)and low alloy(LA)steel.Different status of welding interfaces was prepared by cladding SS consumables to LA steel substrates with different heat inputs via tungsten inert gas arc welding(TIG),followed by a series of microstructural characterizations and hardness tests.Results showed that a hardening and transition layer(TL)would be generated along the welding interface,and the width and hardening degree of the TL would increase with the heat input.Meanwhile,heavy load hardness tests showed that highly severe inhomogeneous plastic deformation and the microcrack would be generated in the interfacial region and the welding interface respectively in the highest heat input sample(1.03 kJ/mm).These results indicate that the increase in heat input would deteriorate the bonding performance of DMW joints.Further microstructural observations showed that the higher hardening degree of the highest heat input sample was mainly attributed to the stronger grain boundary,solution,and dislocation strengthening effects. 展开更多
关键词 welding interface transition layer heat input MICROSTRUCTURE hardness
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Relationship between Hardness and Deformation during Cold Rolling Process of Complex Profles 被引量:1
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作者 Dawei Zhang Linghao Hu +1 位作者 Bingkun Liu Shengdun Zhao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第5期315-329,共15页
The hardening on surface of complex profles such as thread and spline manufactured by cold rolling can efectively improve the mechanical properties and surface quality of rolled parts. The distribution of hardness in ... The hardening on surface of complex profles such as thread and spline manufactured by cold rolling can efectively improve the mechanical properties and surface quality of rolled parts. The distribution of hardness in superfcial layer is closely related to the deformation by rolling. To establish the suitable correlation model for describing the relationship between strain and hardness during cold rolling forming process of complex profles is helpful to the optimization of rolling parameters and improvement of rolling process. In this study, a physical analog experiment refecting the uneven deformation during complex-profle rolling process has been extracted and designed, and then the large date set (more than 400 data points) of training samples refecting the local deformation characteristics of complexprofle rolling have been obtained. Several types of polynomials and power functions were adopted in regression analysis, and the regression correlation models of 45# steel were evaluated by the single-pass and multi-pass physical analog experiments and the complex-profle rolling experiment. The results indicated that the predicting accuracy of polynomial regression model is better in the strain range (i.e., ε < 1.2) of training samples, and the correlation relationship between strain and hardness out strain range (i.e., ε > 1.2) of training samples can be well described by power regression model;so the correlation relationship between strain and hardness during complex-profle rolling process of 45# steel can be characterized by a segmented function such as third-order polynomial in the range ε < 1.2 and power function with a ftting constant in the range ε > 1.2;and the predicting error of the regression model by segmented function is less than 10%. 展开更多
关键词 Complex profle Cold rolling Multi passes Equivalent strain Vickers hardness
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Dietary protein levels changed the hardness of muscle by acting on muscle fiber growth and the metabolism of collagen in sub-adult grass carp(Ctenopharyngodon idella) 被引量:1
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作者 Min Dong Lu Zhang +8 位作者 Pei Wu Lin Feng Weidan Jiang Yang Liu Shengyao Kuang Shuwei Li Haifeng Mi Ling Tang Xiaoqiu Zhou 《Journal of Animal Science and Biotechnology》 SCIE CAS CSCD 2023年第2期729-744,共16页
Background:Nutrient regulation has been proven to be an effective way to improve the flesh quality in fish.As a necessary nutrient for fish growth,protein accounts for the highest proportion in the fish diet and is ex... Background:Nutrient regulation has been proven to be an effective way to improve the flesh quality in fish.As a necessary nutrient for fish growth,protein accounts for the highest proportion in the fish diet and is expensive.Although our team found that the effect of protein on the muscle hardness of grass carp was probably related to an increased collagen content,the mechanism for this effect has not been deeply explored.Moreover,few studies have explored the protein requirements of sub-adult grass crap(Ctenopharyngodon idella).Therefore,the effects of different dietary protein levels on the growth performance,nutritional value,muscle hardness,muscle fiber growth,collagen metabolism and related molecule expression in grass carp were investigated.Methods:A total of 450 healthy grass carp(721.16±1.98 g)were selected and assigned randomly to six experimen-tal groups with three replicates each(n=25/replicate),and were fed six diets with 15.91%,19.39%,22.10%,25.59%,28.53%and 31.42%protein for 60 d.Results:Appropriate levels of dietary protein increased the feed intake,percentage weight gain,specific growth rate,body composition,unsaturated fatty acid content in muscle,partial free amino acid content in muscle,and muscle hardness of grass carp.These protein levels also increased the muscle fiber density,the frequency of new muscle fibers,the contents of collagen and IGF-1,and the enzyme activities of prolyl 4-hydroxylases and lysyloxidase,and decreased the activity of matrix metalloproteinase-2.At the molecular level,the optimal dietary protein increased col-lagen type Iα1(Colα1),Colα2,PI3K,Akt,S6K1,La ribonucleoprotein domain family member 6a(LARP6a),TGF-β1,Smad2,Smad4,Smad3,tissue inhibitor of metalloproteinase-2,MyoD,Myf5,MyoG and MyHC relative mRNA levels.The levels of the myostatin-1 and myostatin-2 genes were downregulated,and the protein expression levels of p-Smad2,Smad2,Smad4,p-Akt,Akt,LARP6 and Smad3 were increased.Conclusions:The appropriate levels of dietary protein promoted the growth of sub-adult grass carp and improved muscle hardness by promoting the growth of muscle fibers,improving collagen synthesis and depressing collagen degradation.In addition,the dietary protein requirements of sub-adult grass carp were 26.21%and 24.85%according to the quadratic regression analysis of growth performance(SGR)and the muscle hardness(collagen content),respectively. 展开更多
关键词 Collagen degradation Collagen synthesis Grass carp Muscle fibers Muscle hardness PROTEIN
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Influence of quenching medium on the dendrite morphology,hardness,and tribological behaviour of cast Cu-Ni-Sn spinodal alloy for defence application 被引量:1
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作者 Bipin Sankar Karthik V Shankar +4 位作者 Vamu Sunil Hemanth Kashyap S Nikhil Nair Adarsh A.Nair Abhinav P M 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第12期83-100,共18页
Cu-Ni-Sn spinodal alloys(Spinodal bronze)are potential materials with robust applications in components associated with defence applications like bearings,propellers,bushes,and shafts of heavily loaded aircraft,off-ro... Cu-Ni-Sn spinodal alloys(Spinodal bronze)are potential materials with robust applications in components associated with defence applications like bearings,propellers,bushes,and shafts of heavily loaded aircraft,off-road vehicles,and warships.This paper presents a comparative study using water,Brine solution,and SAE 40 oil as the quenching media in regular bronze(Cu-6Sn)and spinodal bronze(Cu-9Ni-6Sn)alloys.Morphological analysis was conducted by optical microscopy,transmission electron microscopy(TEM),and X-ray diffraction technique(XRD)on bronze and spinodal bronze samples immersed in the three different quenching media to understand the grain size and hardness values better.Tribological analysis was performed to analyze the effect of quenching media on the wear aspects of bronze and spinodal bronze samples.The hardness value of the brine-aged spinodal bronze samples was as high as 320 Hv,and the grain size was very low in the range of 60μm.A quantitative comparison between brine-aged regular bronze and brine-aged spinodal bronze showed that the hardness(Hv)was almost 80%higher for brine-aged spinodal bronze.Further,the grain size was approximately 30%finer for spinodal bronze when compared with regular bronze.When the load was increased in spinodal bronze samples,there was an initial dip in wear rate followed by a marginal increase.There was a steady increase in friction coefficient with a rise in load for brine-aged regular bronze and spinodal bronze samples.These results indicate that brine solution is the most effective quenching medium for cast Cu-Ni-Sn spinodal alloys. 展开更多
关键词 Quenching Water BRINE SAE 40 oil Grain size hardness Wear rate Spinodal decomposition CuSn Spinodal alloy CuNiSn
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Friction welding influence on microstructure,microhardness and hardness behavior of CrNiMo steel(AISI 316)
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作者 Ammar Jabbar Hassan Billel Cheniti +3 位作者 Brahim Belkessa Taoufik Boukharouba Djamel Miroud Nacer-Eddine Titouche 《China Welding》 CAS 2023年第3期21-27,共7页
For joining high Cr,Ni and Mo austenitic stainless steel(AISI 316)by direct drive friction welding(DDFW),with friction weld-ing conditions:rotation speed of 3000 r/min,friction time of 10 s,friction pressure of 130 MP... For joining high Cr,Ni and Mo austenitic stainless steel(AISI 316)by direct drive friction welding(DDFW),with friction weld-ing conditions:rotation speed of 3000 r/min,friction time of 10 s,friction pressure of 130 MPa,forge time of 5 s and forge pressure of 260 MPa.The results of microstructure showed that the temperature at the interface reached 819℃while forge applied between 357-237℃,which subdivided welded joint into four distinct regions of highly plastically deformed zone(HPDZ),thermo-mechanically affected zone(TMAZ),heat affected zone(HAZ)and the base metal,with grain size about 10µm,100µm,90µm and 30µm respectively.These re-gions were created due to dynamic recrystallization(DRX)at the interface and thermo-mechanical deformation with heat diffusion in the neighboring regions.Whereas,high level of microhardness about 300 HV0.1 and hardness roughly 240 Hv10 at the interface due to HPDZ creation while low level of 240 HV0.1 for microhardness and moderately of 205 HV10 for hardness in neighboring regions. 展开更多
关键词 friction welding austenitic stainless steel MICROSTRUCTURE MICROhardness hardness
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Effect of Dynamic Strain Aging on Hardness in the Heat-Affected Zone of SUS316 Steel Welds
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作者 Lina Yu Kazutoshi Nishimoto Kazuyoshi Saida 《材料科学与工程(中英文A版)》 2023年第1期13-25,共13页
DSA(dynamic strain aging)phenomenon in SUS316 steel was investigated using isothermal and non-isothermal tensile tests of simulated HAZ(heat-affected zone)thermal cycles.Isothermal tensile tests were performed on SUS3... DSA(dynamic strain aging)phenomenon in SUS316 steel was investigated using isothermal and non-isothermal tensile tests of simulated HAZ(heat-affected zone)thermal cycles.Isothermal tensile tests were performed on SUS316 in the peak temperature range of 20-700°C,with strain rates varying from 4.2×10^(-3)to 4.2×10^(-5)s^(-1).Based on the appearance of discontinuous plastic flows,expressed as serrations,and the hardening phenomenon of the tensile samples,the conditions for the occurrence of DSA in the SUS316 steel were investigated.Furthermore,the extent of hardening due to DSA was evaluated by comparing the hardness values of the SUS316 and SUS316EHP steels after the tensile tests.To confirm the effect of DSA on hardness in the HAZ of the welded SUS316 steel,non-isothermal tensile tests of the simulated HAZ thermal cycles were performed using a Thermec Master.The relationship between the increase in Vickers hardness due to DSA and the strain in the HAZ was determined;the effect of DSA on hardness in the HAZ could be predicted.The DSA in SUS316 steel was found to be mainly attributed to the dynamic interaction of dislocations with C and N interstitial atoms during high-temperature deformation. 展开更多
关键词 Dynamic strain aging hardness SERRATION heat-affected zone SUS316
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热处理对2205双相不锈钢显微组织及性能的影响 被引量:1
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作者 王良 杨茗凯 +3 位作者 胡议文 周培山 郑华林 王斌 《材料热处理学报》 CAS CSCD 北大核心 2024年第2期120-128,共9页
采用光学显微镜、显微硬度计和电化学工作站等研究了2205双相不锈钢经不同温度保温不同时间后的显微组织及性能,并分析了其经不同工艺热处理后的γ和α两相比例和析出相的变化。结果表明:2205双相不锈钢初始状态下α和γ相含量分别为41... 采用光学显微镜、显微硬度计和电化学工作站等研究了2205双相不锈钢经不同温度保温不同时间后的显微组织及性能,并分析了其经不同工艺热处理后的γ和α两相比例和析出相的变化。结果表明:2205双相不锈钢初始状态下α和γ相含量分别为41.2%和58.8%。保温时间相同时,随着热处理温度的升高,γ相含量减少,σ相含量先增加后减少,硬度增加,腐蚀电位先降低后增加。保温温度相同时,随着保温时间的延长(0.5~2 h),γ相和σ相含量增加,γ相含量增幅为2.43%~3.87%,σ相含量增幅为0.05%~0.08%,晶粒有长大趋势,硬度逐渐降低,腐蚀电位总体呈降低趋势。当加热温度为950和1000℃时,硬度随保温时间增加而降低的幅度较明显。σ相含量及α/γ比例增加是造成2205双相不锈钢耐腐蚀性能下降的主要原因。 展开更多
关键词 2205双相不锈钢 热处理 显微组织 硬度 耐蚀性
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中晚熟蟠桃新品种中蟠104的选育 被引量:1
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作者 潘磊 牛良 +4 位作者 孙世航 段文宜 崔国朝 王志强 曾文芳 《果树学报》 CAS CSCD 北大核心 2024年第4期777-780,共4页
中蟠104是通过多代人工杂交聚合选育的中晚熟黄肉蟠桃新品种,其母本为晚熟黄肉桃优系‘06-3-137’,父本为早熟黄肉蟠桃优株‘07北5-60’。花为蔷薇型,粉红色花瓣,花瓣数5片,花粉多,自花结实,丰产稳产。在郑州地区果实8月上旬成熟,果实... 中蟠104是通过多代人工杂交聚合选育的中晚熟黄肉蟠桃新品种,其母本为晚熟黄肉桃优系‘06-3-137’,父本为早熟黄肉蟠桃优株‘07北5-60’。花为蔷薇型,粉红色花瓣,花瓣数5片,花粉多,自花结实,丰产稳产。在郑州地区果实8月上旬成熟,果实生育期137 d左右。单果质量241 g,果实扁平,果顶闭合性好;果皮茸毛短,底色黄色,果面全红;套袋后果面全黄;果肉黄色,硬溶质,黏核;肉质细腻,可溶性固形物含量(w)15.2%,风味甜香。 展开更多
关键词 蟠桃 新品种 中蟠104 黄肉 硬溶质 中晚熟
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长江三角洲北翼第一硬土层理化特征及其地质成因
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作者 朱锦旗 龚绪龙 +4 位作者 苟富刚 张平 张岩 杨磊 刘源 《地质通报》 CAS CSCD 北大核心 2024年第1期1-12,共12页
在长江河口两翼广泛分布第一硬土层(FHSL),研究其形成机制及工程地质特性对工程建设具有很好的指导意义。根据调查资料(钻孔935个,累计进尺42128 m)和试验资料,首次精确确认了长江河口北翼第一硬土层分布界线,研究了第一硬土层的形成年... 在长江河口两翼广泛分布第一硬土层(FHSL),研究其形成机制及工程地质特性对工程建设具有很好的指导意义。根据调查资料(钻孔935个,累计进尺42128 m)和试验资料,首次精确确认了长江河口北翼第一硬土层分布界线,研究了第一硬土层的形成年代、粒度特征、地球化学特征、工程地质特性等。研究表明:第一硬土层形成年龄为20~11 ka B.P.(多个光释光和14C测年资料);硬土层含水率随深度的增加有增大的趋势,表明气候自下向上逐渐变凉和变干;第一硬土层的颗粒级配、粒度分布频率曲线、C-M沉积图等特征显示,第一硬土层主要由粉砂、极细砂和粘土粒级组成,样品的粒度频率曲线主要呈单峰分布,反映出物质沉积前所受搬运营力性质单一,土体颗粒沉积以均匀悬浮占绝对优势,沉积环境是一种相对稳定的低能环境。第一硬土层的发育受气候控制,大致可以分为3个阶段:第1阶段(20~15 ka B.P.)为沉积与成土交替作用时期,且以沉积作用为主,硬土层剖面厚度主要受该阶段控制,至末次盛冰期结束;第2阶段(15~11 ka B.P.)为暴露成土期,这时洪水不能形成越岸沉积,加积作用基本停止,硬土层厚度不再明显增加,已形成的第一硬土区域受到频繁变迁的分合河网的侵蚀切割,形成多条不规则古河道和台地,硬土层逐渐脱水成陆,经历了风化成壤的过程;第3阶段(11 ka B.P.至今)为淹埋期,随着全新世的到来,气候变暖,海平面不断上升,硬土层被其上覆的海相沉积层掩埋,成岩作用开始直到现今。土体易溶盐含量较高,为典型氯盐渍土类型,自下而上具有从低变高的趋势,为海相层覆盖硬土层以后成岩过程造成的。 展开更多
关键词 古土壤 硬土层 硬质粘土层 粒度 沉积环境 成因机制
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不同摩擦副条件下二硫化钼薄膜的摩擦学性能研究 被引量:1
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作者 冯兴国 郑玉刚 +3 位作者 汪科良 杨拉毛草 张凯锋 周晖 《真空与低温》 2024年第1期31-38,共8页
为了研究MoS_(2)-Ti薄膜与9Cr18钢、W-DLC和DLC薄膜的摩擦学行为,分别采用磁控溅射技术和等离子体增强化学气相沉积技术在9Cr18钢表面沉积了MoS_(2)-Ti薄膜、W-DLC和DLC薄膜。用扫描电子显微镜(SEM)、能量色散谱仪(EDS)和X射线衍射仪(X... 为了研究MoS_(2)-Ti薄膜与9Cr18钢、W-DLC和DLC薄膜的摩擦学行为,分别采用磁控溅射技术和等离子体增强化学气相沉积技术在9Cr18钢表面沉积了MoS_(2)-Ti薄膜、W-DLC和DLC薄膜。用扫描电子显微镜(SEM)、能量色散谱仪(EDS)和X射线衍射仪(XRD)研究了薄膜的表面形貌、化学成分和相组成。利用纳米压痕仪和球-盘摩擦试验机对不同薄膜的纳米硬度和摩擦学性能进行了分析。研究结果表明,MoS_(2)-Ti薄膜与DLC薄膜的摩擦因数和磨损率最小。相比MoS_(2)-Ti薄膜与不镀膜的9Cr18钢球摩擦副,MoS_(2)-Ti薄膜与W-DLC薄膜摩擦副的摩擦因数和磨损率没有减小。MoS_(2)-Ti薄膜与W-DLC薄膜摩擦副的磨损机制为磨粒磨损和黏着磨损,与DLC薄膜摩擦副的磨损机制为黏着磨损。摩擦副表面沉积DLC薄膜有助于降低MoS_(2)-Ti薄膜的摩擦因数和磨损率。 展开更多
关键词 MoS_(2)-Ti薄膜 表面形貌 硬度 摩擦学性能
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具有独立缓冲结构的PDC—牙轮复合钻头研制 被引量:1
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作者 杨迎新 牛世伟 +4 位作者 陈炼 李枝林 任海涛 姚建林 杨燕 《天然气工业》 EI CAS CSCD 北大核心 2024年第5期96-104,共9页
油气勘探开发过程中,难钻地层钻井效率低、钻头寿命短是影响深井、超深井钻井周期和成本的瓶颈问题。钻头工作过程中切削结构轮流与井壁接触而产生的多边形效应是导致钻头不稳定工作、切削齿冲击失效的主要因素。为提高钻头工作稳定性,... 油气勘探开发过程中,难钻地层钻井效率低、钻头寿命短是影响深井、超深井钻井周期和成本的瓶颈问题。钻头工作过程中切削结构轮流与井壁接触而产生的多边形效应是导致钻头不稳定工作、切削齿冲击失效的主要因素。为提高钻头工作稳定性,提出了具有独立缓冲结构的PDC—牙轮复合钻头新结构,并针对四川盆地茅口组Ø311.2 mm井段常规PDC钻头冲击失效严重的问题,设计了3+3+3型(3个主刀翼、3个牙轮以及3个独立缓冲刀翼)的独立缓冲结构复合钻头,开展了全尺寸钻头室内钻进对比实验,并在川渝页岩气区块茅口组—栖霞组地层进行了实钻应用。研究结果表明:①独立缓冲结构复合钻头在常规复合钻头的牙轮切削结构和固定切削结构之间的空隙部位增设独立缓冲刀翼,有效缓解了多边形效应,对PDC齿形成很好的缓冲保护,同时分担了过大的钻压,限制了切削齿吃入深度,进而防止了钻头产生粘滑振动;②独立缓冲结构复合钻头钻压和扭矩波动小,扭矩为PDC钻头的1/5;③独立缓冲结构复合钻头取得了单只钻头进尺170 m的记录,比邻井同层位单只PDC钻头最高进尺提高了73.5%。结论认为,独立缓冲刀翼对提高钻头的稳定性起到了关键作用,不仅提高了钻头寿命,而且有效提高了复杂难钻地层及复杂结构井的综合钻井时效,有效降低了油气勘探开发成本。 展开更多
关键词 复合钻头 独立缓冲 多边形效应 钻头稳定性 钻井提速 硬地层
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政府债务预算硬约束与地方财政可持续性提升 被引量:4
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作者 洪源 万里 +1 位作者 秦玉奇 单昱 《中国软科学》 CSCD 北大核心 2024年第1期201-213,共13页
地方政府债务风险的不断积累已成为地方财政可持续性的最大阻碍。以新《预算法》实施后,地方政府债务管理的“开前门”和“关后门”两个阶段改革为准自然实验,分析了政府债务预算硬约束对地方财政可持续性的影响。研究发现:地方政府债... 地方政府债务风险的不断积累已成为地方财政可持续性的最大阻碍。以新《预算法》实施后,地方政府债务管理的“开前门”和“关后门”两个阶段改革为准自然实验,分析了政府债务预算硬约束对地方财政可持续性的影响。研究发现:地方政府债务管理的两阶段改革都对地方财政可持续性具有显著的正向提升影响;从作用机制来看,“开前门”和“关后门”阶段改革分别通过财政收支巩固和债务规模控制来发挥对地方财政可持续性的有效作用;异质性分析来看,地方政府举债行为激励较弱和财政监管力度较高的地方,政府债务预算硬约束对地方财政可持续性的正向效应会更加显著。研究结果为推进债务预算硬约束来防范地方政府债务风险和提升地方财政可持续性提供了政策启示。 展开更多
关键词 债务预算硬约束 地方财政可持续性 地方政府债务管理改革
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氧化物光学薄膜的压入硬度研究
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作者 马孜 李斌 +2 位作者 童静 姚德武 沈刚 《激光技术》 CAS CSCD 北大核心 2024年第3期340-344,共5页
为了评价离子源辅助对不同氧化物薄膜的影响,采用不同的镀膜设备沉积了TiO_(2)、Ta_(2)O_(5)、ZrO_(2)、SiO_(2)氧化物单层膜,用椭偏仪测量了其折射率和厚度,并用纳米压痕仪测量了不同载荷下材料的杨氏模量和纳米硬度,比较了不同离子源... 为了评价离子源辅助对不同氧化物薄膜的影响,采用不同的镀膜设备沉积了TiO_(2)、Ta_(2)O_(5)、ZrO_(2)、SiO_(2)氧化物单层膜,用椭偏仪测量了其折射率和厚度,并用纳米压痕仪测量了不同载荷下材料的杨氏模量和纳米硬度,比较了不同离子源沉积条件下膜层这两个参数的变化。结果表明,离子源辅助能有效增加膜层杨氏模量和压入硬度,TiO_(2)增加了2 GPa,Ta_(2)O_(5)增加了4 GPa,ZrO_(2)增加了2 GPa,和膜层的折射率变化趋势是一致的。纳米压痕法也可作为评价离子源轰击能力的一种手段。 展开更多
关键词 薄膜 纳米压痕 压入硬度 氧化物
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BEVTrack:基于难例挖掘训练的端到端三维多目标跟踪方法 被引量:1
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作者 张弘 万家旭 +2 位作者 陈海波 张健 李旭亮 《信号处理》 CSCD 北大核心 2024年第1期152-165,共14页
多目标跟踪已经成为自动驾驶系统中的一个关键组成部分,其目的是在连续的视频流与点云流中识别、定位并标识所有感兴趣的目标。目前三维多目标跟踪方法多依赖人工多阶段调参以保证整体跟踪性能,难以对复杂遮挡或运动进行有效建模。而现... 多目标跟踪已经成为自动驾驶系统中的一个关键组成部分,其目的是在连续的视频流与点云流中识别、定位并标识所有感兴趣的目标。目前三维多目标跟踪方法多依赖人工多阶段调参以保证整体跟踪性能,难以对复杂遮挡或运动进行有效建模。而现有的三维端到端多目标跟踪方法,如MUTR等,精度普遍较低。其核心原因为三维空间中的特征聚合和感知相对于二维图像更具挑战性,简单的网络难以实现复杂的三维特征聚合,并大量的噪声信息与难例信息干扰严重,影响模型的特征提取能力。针对以上问题,本文提出了一种基于难例挖掘训练的端到端多目标跟踪框架BEVTrack。针对三维特征关联问题,本文设计了基于鸟瞰图(BEV)位置编码的三维跟踪查询。通过基于BEV特征的三维跟踪查询,本文方法能够更好地将跟踪查询与实际三维特征进行有效关联,从而大幅度提升了跟踪精度。同时,模型依靠BEV数据进行特征关联,仅需轻量化的网络便可以实现快速有效的跟踪。针对数据噪声问题,本文提出了面向多目标跟踪的难例挖掘训练,通过针对检测难例与跟踪难例分别处理,训练模型去除检测错误噪声与跟踪匹配的能力,从而提升在真实场景下模型处理噪声信息与难例干扰的能力。在实验结果方面,基于Nuscenes数据集,我们进行了大量的对比实验与模型消融实验,实验结果证明本文的方法在该数据集上取得了领先的性能。 展开更多
关键词 多目标跟踪 端到端 难例挖掘 TRANSFORMER
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超声振动在矿山煤岩致裂中的研究进展与展望 被引量:1
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作者 王旭锋 牛志军 +4 位作者 张磊 李翔宇 王纪尧 常泽超 陈旭阳 《煤炭科学技术》 EI CAS CSCD 北大核心 2024年第1期232-243,共12页
为了推动超声振动致裂煤岩体技术的发展,提高矿山煤层气增产及硬岩掘进的效率,回顾了超声波技术的发展历程,综述了超声振动在致裂煤岩体方面的应用现状与研究进展,明确了超声振动在煤岩致裂领域存在的关键阻碍性技术难题及发展趋势。(1... 为了推动超声振动致裂煤岩体技术的发展,提高矿山煤层气增产及硬岩掘进的效率,回顾了超声波技术的发展历程,综述了超声振动在致裂煤岩体方面的应用现状与研究进展,明确了超声振动在煤岩致裂领域存在的关键阻碍性技术难题及发展趋势。(1)总结了传统技术在矿山煤层气增产和硬岩掘进领域存在的技术问题,介绍了超声波技术的独特优势及应用领域,阐述了超声波发生器和超声波换能器的发展阶段及相应性能;(2)归结了超声振动煤层气促解增渗装置及流程,分析了超声振动煤层气促解增产现状,阐明了超声空化效应、机械振动效应、热效应作用下煤层气降压、加速、位能及动能增加进而促进其解吸增渗的机制;(3)归纳了超声振动破岩装置及流程,阐述了超声振动破碎硬岩的进展,揭示了超声振动产生的机械振动效应与热效应作用下疲劳损伤、微裂纹亚临界扩展、矿物颗粒不均匀热膨胀或矿物相变、岩石物理力学特性劣化导致硬岩破碎的内在机理;(4)针对超声波发生器、换能器及超声振动在矿山致裂煤岩体中的局限度,对未来超声振动致裂煤岩体在现场高效应用的研究重点提出了4点建议:高性能防爆型超声波发生器和换能器的研发,超声振动促解增渗机理的深入分析及管线技术框架设计,多功能及多场耦合室内超声振动致裂煤岩体设备研制与试验,井下抗干扰超声振动设备的研发应用。 展开更多
关键词 采矿工程 超声作用装置 超声振动 煤层气增渗 硬岩破碎
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巷帮煤体整体滑脱型冲击地压锚杆防冲支护原理及工程实践 被引量:1
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作者 韩军 李广汉 +2 位作者 郭宝龙 马双文 CAO Chen 《煤炭科学技术》 EI CAS CSCD 北大核心 2024年第1期117-125,共9页
冲击地压是目前严重影响煤炭安全有效开采的灾害之一,研究锚杆防冲支护原理和技术对防治巷道冲击地压灾害具有重要意义和价值。通过对巷帮煤体整体冲入型冲击地压发生的地质条件以及破坏特征进行总结分析,认为坚硬顶板与坚硬煤层是此类... 冲击地压是目前严重影响煤炭安全有效开采的灾害之一,研究锚杆防冲支护原理和技术对防治巷道冲击地压灾害具有重要意义和价值。通过对巷帮煤体整体冲入型冲击地压发生的地质条件以及破坏特征进行总结分析,认为坚硬顶板与坚硬煤层是此类型冲击地压的重要地质特征,而巷帮煤体整体滑脱是其主要冲击破坏特征。在此基础上,以巷帮滑脱煤体为研究对象,建立了顶板-巷道-底板复合结构体力学模型,建立了巷帮煤体发生水平滑移的极限平衡方程,并对各个参数进行分析。结果表明:由于顶板反弹使巷帮煤体竖直方向压力降低,巷帮煤体被构造应力推入巷道发生冲击地压。基于该发生机制模型,认为目前的锚杆支护设计体系在防治巷帮煤体冲入型冲击地压存在不足,并基于其发生和破坏特征,建立了针对巷帮煤体整体滑脱型冲击地压的锚杆防冲支护设计原则,即将顶和底帮锚杆锚固端分别穿层打入稳定的顶底板内,并使用长锚索取代中部帮锚杆,提供锚杆支护的防冲作用。基于新建立的锚杆防冲支护设计方法,以大屯矿区孔庄煤矿7305工作面防冲支护为工程背景,在宽煤柱段巷帮锚杆支护采取了防冲设计,帮顶、底部锚杆及补强锚索均锚固于顶底板内部,能够有效吸收煤体滑动动能,提高安全性。 展开更多
关键词 冲击地压 坚硬顶板 回采巷道 整体滑脱 锚杆防冲支护
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WC对316 L钢表面的镍基激光熔覆涂层的性能影响研究
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作者 吴敬权 李德荣 +3 位作者 安芬菊 黄江 王有明 吴香林 《激光技术》 CAS CSCD 北大核心 2024年第5期677-683,共7页
为了提升316L不锈钢的耐腐蚀性能,延长其在海洋环境中的使用寿命,讨论了激光熔覆技术在316L基材表面熔覆了纯Ni60涂层和WC+Ni60复合涂层的方法和效果。WC+Ni60复合涂层结合了WC颗粒的硬度和Ni60基体的韧性,具有更优异的综合性能,适用于... 为了提升316L不锈钢的耐腐蚀性能,延长其在海洋环境中的使用寿命,讨论了激光熔覆技术在316L基材表面熔覆了纯Ni60涂层和WC+Ni60复合涂层的方法和效果。WC+Ni60复合涂层结合了WC颗粒的硬度和Ni60基体的韧性,具有更优异的综合性能,适用于对基材表面进行更高强度的保护。分别利用硬度仪、X射线衍射仪和电化学工作站对涂层检索和测试。结果表明,WC+Ni60复合涂层的平均截面硬度为719 HV,但各区域波动较大,同时熔覆层表面相较纯Ni60涂层更耐腐蚀,自腐蚀电位提高了0.12 V,自腐蚀电流密度降低了2.49×10^(-6)A/cm^(2)。本研究为后期制备耐海水腐蚀复合涂层提供了参考。 展开更多
关键词 激光技术 激光熔覆 微观组织 硬度 耐腐蚀性
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基于层次分析法的TBM滚刀评价方式 被引量:1
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作者 李雪 陈霖 +3 位作者 霍鹏 马文帅 龚子邦 吴九七 《城市轨道交通研究》 北大核心 2024年第2期38-42,47,共6页
[目的]为了减少TBM(硬岩隧道掘进机)在高磨蚀性岩层中掘进时的换刀次数,以及选出最适用于高磨蚀性岩层的滚刀,提出一种基于层次分析法的滚刀评价方法。[方法]建立了滚刀磨损失效危害评价模型;选取7个磨损失效类型因素,基于层次分析法建... [目的]为了减少TBM(硬岩隧道掘进机)在高磨蚀性岩层中掘进时的换刀次数,以及选出最适用于高磨蚀性岩层的滚刀,提出一种基于层次分析法的滚刀评价方法。[方法]建立了滚刀磨损失效危害评价模型;选取7个磨损失效类型因素,基于层次分析法建立了滚刀磨损失效危害评价模型和比较判断矩阵,计算出各失效类型危害的占比;以广佛东环城际铁路大源站至太和站区间线路为例,对4个常用品牌的滚刀进行定量分析;建立风险评价分值表,分析4个品牌的滚刀在使用过程中的失效影响评价值。[结果及结论]高磨蚀岩层中的滚刀非正常磨损占比为23.29%,正常磨损占比为76.71%。c品牌和d品牌滚刀的失效影响评价值分别为7.141和4.816,远小于a品牌滚刀的失效影响评价值7.587和b品牌滚刀的失效影响评价值9.058。d品牌滚刀的相对磨损速率大于c品牌滚刀,因此c品牌滚刀最适用于高磨蚀性岩层。a品牌滚刀适用于硬度极大的岩层,b品牌滚刀不推荐使用,d品牌滚刀适用于硬度较小的岩层。 展开更多
关键词 硬岩隧道 层次分析法 滚刀评价方式
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