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柴油机各缸工作状况的鉴别
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作者 王文 《河北农机》 1994年第1期11-11,共1页
柴油机各缸工作状况的鉴别多缸柴油机某一缸工作不正常,是常见的故障,要查明某一缸工作状况,可采用以下方法:一、观烟色通过观察柴油机排出的烟色和排气是否连续,可判定各缸的工况。柴油机正常工作时,排气的一般烟色为淡灰色,负... 柴油机各缸工作状况的鉴别多缸柴油机某一缸工作不正常,是常见的故障,要查明某一缸工作状况,可采用以下方法:一、观烟色通过观察柴油机排出的烟色和排气是否连续,可判定各缸的工况。柴油机正常工作时,排气的一般烟色为淡灰色,负荷较重时为深灰色。若为黑色,说明可... 展开更多
关键词 柴油机 工作状况 喷油器 爆发声 单缸供油量 高压油管 喷油泵 可燃气体 柴油机转速 未完全燃烧
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1E40FP型汽油机几例特殊故障原因分析
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作者 旭平 《山东农机化》 1997年第5期17-17,共1页
一、起动后很快熄火。发生此故障的汽油机虽能顺利起动,但不能正常运转。自动熄火后重新起动,仍不能正常工作。产生此故障的原因如下:(1)化油器主量孔堵塞。(2)浮子损坏。(3)火花塞绝缘性能变差,受热后短路。
关键词 FP型 特殊故障 汽油机 原因分析 量孔 绝缘性能 粗器 火花塞积炭 爆发声 清除积炭
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怎样检查柴油机各缸工作状况
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作者 江选兴 《农业开发与装备》 1998年第2期15-16,共2页
柴油机各缸工作是否正常,较难直接观察到,但可在发动机怠速运转时,通过以下五种方法检查: 1.听音法 柴油机在怠速运转时,用听诊器或借助金属棍,触及机体靠近喷油器的部位,倾听各缸爆发的声音。正常的声音类似敲击金属“(口当)、(口当)... 柴油机各缸工作是否正常,较难直接观察到,但可在发动机怠速运转时,通过以下五种方法检查: 1.听音法 柴油机在怠速运转时,用听诊器或借助金属棍,触及机体靠近喷油器的部位,倾听各缸爆发的声音。正常的声音类似敲击金属“(口当)、(口当)”的响声。若有“嗬、嗬” 展开更多
关键词 柴油机 工作状况 喷油器 供油量 爆发声 怠速运转 排气管 发动机 五种方法 高压油管
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柴油机各缸工作的检查
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作者 李恕忠 《农业开发与装备》 1997年第2期26-27,共2页
柴油机各缸工作是否正常,较难直接观察到,但可在发劫机怠速运转中,通过如下方法检查: 1.听音法 发动机在怠速运转中,用听诊器或借助金属棍,触及机体靠近喷油器的部位,倾听各缸爆发的声音。正常的声音类似敲击金属“当、当”的响声。只... 柴油机各缸工作是否正常,较难直接观察到,但可在发劫机怠速运转中,通过如下方法检查: 1.听音法 发动机在怠速运转中,用听诊器或借助金属棍,触及机体靠近喷油器的部位,倾听各缸爆发的声音。正常的声音类似敲击金属“当、当”的响声。只有“嗬、嗬” 展开更多
关键词 柴油机 喷油器 发动机工作 爆发声 供油量 发动机转速 排气管 运转中 高压油管 完全燃烧
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柴油机各缸工作情况检查方法
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作者 于丽萍 《内燃机与动力装置》 1999年第4期11-11,共1页
柴油机各缸工作情况可在怠速运转时用如下方法检查: (1)听音法 用听诊器或借助金属棍,靠近喷油器体,倾听各缸爆发的声音。正常的声音类似金属敲击“当、当”的响声。若只有“嗬嗬”连续不干脆的响声时,则该缸供油量太少,或是没有及时着... 柴油机各缸工作情况可在怠速运转时用如下方法检查: (1)听音法 用听诊器或借助金属棍,靠近喷油器体,倾听各缸爆发的声音。正常的声音类似金属敲击“当、当”的响声。若只有“嗬嗬”连续不干脆的响声时,则该缸供油量太少,或是没有及时着火。如敲击声很大,说明该缸供油量太大或喷油时间过早。 (2)观色法 柴油机工作正常时,排出的废气颜色为淡灰色,负荷大时略深。如排黑烟,说明可燃气体燃烧不完全。排蓝烟,表明润滑油进入气缸内燃烧。排白烟,则说明柴油中有水,有时可燃气体未燃烧也排白烟。排气管连续排出不正常的烟色,说明各缸工作均不正常;如断续排烟,说明个别缸工作不正常。 (3)感温法 在柴油机起动后的最初阶段(工作一段时间后排气管温度很高,用手触摸会被烫伤),用手摸各缸排气歧管的温度,可鉴别各缸工作情况。如某缸排气歧管的温度比其他缸高,说明该缸供油量偏大; 展开更多
关键词 柴油机 工作情况 供油量 排气歧管 喷油器体 爆发声 柴油机起动 缸内燃烧 可燃气体 气体燃烧
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Experimental investigation on failure process and spatio-temporal evolution of rockburst in granite with a prefabricated circular hole 被引量:13
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作者 LIU Chong-yan ZHAO Guang-ming +4 位作者 XU Wen-song MENG Xiang-rui HUANG Shun-jie ZHOU Jun WANG Yun-kun 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第10期2930-2944,共15页
To study the mechanism of rockburst and its spatio-temporal evolution criterion,a rockburst simulation experiment was performed on granite specimens,each with a prefabricated circular hole,under different lateral load... To study the mechanism of rockburst and its spatio-temporal evolution criterion,a rockburst simulation experiment was performed on granite specimens,each with a prefabricated circular hole,under different lateral loads.Using micro camera,acoustic emission(AE)system,and infrared thermal imager,the AE characteristics and thermal radiation temperature migration were studied during the rockburst process.Then,the failure mode and damage evolution of the surrounding rock were analyzed.The results demonstrate that increasing the lateral load can first increase and then reduce the bearing capacity of the hole.In this experiment,the hole failure process could be divided into four periods:quiet,particle ejection,stability failure and collapse.Correspondingly,the AE signals evolved from a calm stage,to have intermittent appearance;then,they were continuous with a sudden increase,and finally increased dramatically.The failure of the surrounding rock was mainly tensile failure,while shear failure tended to first increase and then decrease.Meanwhile,damage to the hole increased gradually during the particle ejection period,whereas damage to the rockburst mainly occurred in the stability failure period.The thermal radiation temperature migration exhibited warming in shallow parts,inward expansion,cooling in the shallow parts with free surface heating,inward expansion,a sudden rise in temperature of the rockburst pits,and finally specimen failure.The initial reinforcement support should fully contribute to surface support.Furthermore,an appropriate tensile capacity and good energy absorption capacity should be established in support systems for high-stress roadways. 展开更多
关键词 ROCKBURST acoustic emission spatio-temporal evolution thermal imaging
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Experimental investigation on synergetic prediction of granite rockburst using rock failure time and acoustic emission energy 被引量:11
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作者 WANG Chun-lai CAO Cong +3 位作者 LI Chang-feng CHUAI Xiao-sheng ZHAO Guang-ming LU Hui 《Journal of Central South University》 SCIE EI CAS CSCD 2022年第4期1262-1273,共12页
The frequent occurrence of rockburst and the difficulty in predicting were considered in deep engineering and underground engineering.In this work,laboratory experiments on rockburst under true triaxial conditions wer... The frequent occurrence of rockburst and the difficulty in predicting were considered in deep engineering and underground engineering.In this work,laboratory experiments on rockburst under true triaxial conditions were carried out with granite samples.Combined with the deformation characteristics of granite,acoustic emission(AE)technology was well applied in revealing the evolution law of micro-cracks in the process of rockburst.Based on the comprehensive analysis of acoustic emission parameters such as impact,ringing and energy,the phased characteristics of crack propagation and damage evolution in granite were obtained,which were consistent with the stages of rock deformation and failure.Subsequently,based on the critical point theory,the accelerated release characteristics of acoustic emission energy during rockburst were analyzed.Based on the damage theory,the damage evolution model of rock under different loading conditions was proposed,and the prediction interval of rock failure time was ascertained concurrently.Finally,regarding damage as an intermediate variable,the synergetic prediction model of rock failure time was constructed.The feasibility and validity of model were verified. 展开更多
关键词 ROCKBURST acoustic emission energy damage failure time synergetic prediction
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Acoustic emission precursors of static and dynamic instability for coarse-grained hard rock 被引量:13
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作者 SU Guo-shao GAN Wei +1 位作者 ZHAI Shao-bin ZHAO Guo-fu 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第10期2883-2898,共16页
To investigate the acoustic emission(AE)precursors of coarse-grained hard rock instability,an experimental study on the rockburst and slabbing process of granite was carried out using a true triaxial test system.The e... To investigate the acoustic emission(AE)precursors of coarse-grained hard rock instability,an experimental study on the rockburst and slabbing process of granite was carried out using a true triaxial test system.The evolution of the AE signals was monitored and analyzed in terms of the AE hit rate,fractal dimension of the AE hit number,AE count rate,b-value,dominant frequency and microcrack type.The test results show that after rock slabbing occurs,the AE precursors that can be used to predict the final dynamic instability(rockburst)are as follows:indicators such as the AE hit rate and AE count rate suddenly increase and then suddenly decrease;the AE hit rate exhibits a“quiet period”;during the“quiet period”,a small number of high-amplitude and low-frequency hits occur,and the signals corresponding to shear fracture continue to increase.The AE precursors for the final static instability(spalling)are as follows:both the AE hit rate and the b-value continuously decrease,and intermittent sudden increases appear in the high-frequency hits or the AE count rate. 展开更多
关键词 ROCKBURST slabbing SPALLING acoustic emission true triaxial test
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Experimental investigation on predicting precursory changes in entropy for dominant frequency of rockburst 被引量:10
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作者 WANG Chun-lai CHEN Zeng +7 位作者 LIAO Ze-feng HOU Xiao-lin LI Hai-tao WANG Ai-wen LI Chang-feng QIAN Peng-fei LI Guang-yong LU Hui 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第10期2834-2848,共15页
Rockburst is a dynamic phenomenon accompanied by acoustic emission(AE)activities.It is difficult to predict rockburst accurately.Based on the fast Fourier transform(FFT)method and the information entropy theory,the ev... Rockburst is a dynamic phenomenon accompanied by acoustic emission(AE)activities.It is difficult to predict rockburst accurately.Based on the fast Fourier transform(FFT)method and the information entropy theory,the evolution model of dominant frequency entropy was established.The AE energy,frequency and stress were synthetically considered to predict rockburst.Under the triaxial and the single-face unloading tests,the relationship between AE energy and the development of internal cracks was analyzed.Using the FFT method,the distribution characteristics of AE dominant frequency values were obtained.Based on the information entropy theory,the dominant frequencies evolved patterns were ascertained.It was observed that the evolution models of the dominant frequency entropy were nearly the same and shared a characteristic“undulation-decrease-rise-sharp decrease”pattern.Results show that AE energy will be released suddenly before rockburst.The density of intermediate frequency increased prior to rockburst.The dominant frequency entropy reached a relative maximum value before rockburst,and then decreased sharply.These features could be used as a precursory information for predicting rockburst.The proposed relative maximum value could be as a key point to predict rockburst.This is a meaningful attempt on predicting rockburst. 展开更多
关键词 ROCKBURST precursory information acoustic emission information entropy dominant frequency evolution model
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Exponential decay law of acoustic emission and microseismic activities caused by disturbances associated with multilevel loading and mining blast 被引量:2
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作者 Shi-da XU Tian-xiao CHEN +1 位作者 Jia-qi LIU Chen-rui ZHANG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第11期3549-3563,共15页
To investigate decay law of acoustic emission and microseismic activities caused by disturbances associated with multilevel loading and mining blast,a new exponential decay(ED)law was proposed.The results show that th... To investigate decay law of acoustic emission and microseismic activities caused by disturbances associated with multilevel loading and mining blast,a new exponential decay(ED)law was proposed.The results show that the micro-fracture activity decay law after multistage stress loading and blasting disturbance conforms to the ED model,in which the sum of A and n represents the number of initial micro-fracture events,and n represents the level of background micro-fracture events.The ED model can describe the number of initial micro-fracture events with a deviation less than 10%.The ED model outperforms the traditional aftershock models in describing the micro-fracture event decay law in the three cases considered.The ED model can provide a reference for selecting the blasting interval in mines,which is of great significance to maintain the stability of the surrounding rock and ensure safe production in metal mines. 展开更多
关键词 exponential decay law blast disturbance acoustic emission microseismic activities metal mine
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Rock burst proneness prediction by acoustic emission test during rock deformation 被引量:14
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作者 张志镇 高峰 尚晓吉 《Journal of Central South University》 SCIE EI CAS 2014年第1期373-380,共8页
Rock burst is a severe disaster in mining and underground engineering,and it is important to predict the rock burst risk for minimizing the loss during the constructing process.The rock burst proneness was connected w... Rock burst is a severe disaster in mining and underground engineering,and it is important to predict the rock burst risk for minimizing the loss during the constructing process.The rock burst proneness was connected with the acoustic emission(AE) parameter in this work,which contributes to predicting the rock burst risk using AE technique.Primarily,a rock burst proneness index is proposed,and it just depends on the heterogeneous degree of rock material.Then,the quantificational formula between the value of rock burst proneness index and the accumulative AE counts in rock sample under uniaxial compression with axial strain increases is developed.Finally,three kinds of rock samples,i.e.,granite,limestone and sandstone are tested about variation of the accumulative AE counts under uniaxial compression,and the test data are fitted well with the theoretic formula. 展开更多
关键词 rock mechanics rock burst proneness PREDICTION accumulative acoustic emission counts Weibull statistical distribution
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Progressive fracture processes around tunnel triggered by blast disturbances under biaxial compression with different lateral pressure coefficients 被引量:13
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作者 Yi LONG Jian-po LIU +4 位作者 Gang LEI Ying-tao SI Chang-yin ZHANG Deng-cheng WEI Hong-xu SHI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2020年第9期2518-2535,共18页
To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions... To investigate the progressive fracture processes around a tunnel triggered by static stress and dynamic disturbance,experiments and numerical simulations were performed.The results show that the spatial distributions of acoustic emission(AE)events become very different as lateral pressure coefficients change.The combined effect of static stress and dynamic disturbance causes the damage around the tunnel,and initial stress conditions control the damage morphology.The blast disturbance cannot fundamentally change the damaged area but will deepen the extent of damage and accelerate the failure speed.The more significant the difference between the vertical and horizontal stresses is,the higher the impact on the tunnel by the dynamic disturbance is.The AE activity recovers to a relatively stable state within a short time after the blast and conforms to power-law characteristics. 展开更多
关键词 tunnel damage blast disturbance lateral pressure coefficient acoustic emission power-law fitting
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A Physical Simulation Test for the RockBurst in Tunnels 被引量:4
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作者 LI Tianbin WANG Xiangfeng MENG Lubo 《Journal of Mountain Science》 SCIE CSCD 2011年第2期278-285,共8页
According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model... According to the test results of the physical and mechanical properties of similar materials in various quality mixture, a type of material with obvious tendency of rockburst was selected to produce a large-size model to simulate rockburst phenomena in tunnels. The prototype model comes from a typical section of diversion tunnels in Jinping Hydropower Station in China. The simulation of excavating tunnels is carried out by opening a hole in the model after loading. The modeling results indicated that under the condition of normal stresses in the model boundaries the arch top, spandrel and side walls of the tunnel produced an obvious jump reaction of stress and strain and the acoustic emission counts of the surrounding rock also increased rapidly in a different time period after the "tunnel" excavation, showing the clear features of rockburst. The spalling, buckling and breaking occurred in the surrounding rock of model in conditions of over loading. It is concluded that the modeling tunnel segment in Jinping Hydropower Station is expected to form the tensile rockburst with the pattern of spalling, buckling and breaking. 展开更多
关键词 ROCKBURST Physical simulation Similar materials (Gypsum Cement Sand Water) Strain jump SPALLING BUCKLING BREAKING
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柴油机各缸工作情况检查方法
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作者 李恕总 《农机安全监理》 北大核心 1998年第3期32-32,共1页
柴油机各缸工作情况检查方法柴油机各缸工作情况可在怠速运转时用如下方法检查。(1)听音法用听诊器或借助金属棍,靠近喷油器体的部位,倾听各缸爆发的声音。正常的声音类似金属敲击“当、当”的响声。若只有“嗬、嗬”连续不干脆的... 柴油机各缸工作情况检查方法柴油机各缸工作情况可在怠速运转时用如下方法检查。(1)听音法用听诊器或借助金属棍,靠近喷油器体的部位,倾听各缸爆发的声音。正常的声音类似金属敲击“当、当”的响声。若只有“嗬、嗬”连续不干脆的响声时,则该缸供油量太少,或是没有... 展开更多
关键词 柴油机 工作情况 供油量 爆发声 喷油器体 检查方法 高压油管 完全燃烧 排气管 喷油泵
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An explosive seismic sounding profile across the transition zone between west Kunlun Mts. and Tarim Basin 被引量:7
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作者 李秋生 高锐 +7 位作者 卢德源 李敬卫 范景义 张之英 刘文 李英康 闫全人 李德兴 《Science China Earth Sciences》 SCIE EI CAS 2001年第7期666-672,共7页
The explosive seismic sounding profile across the transition zone from the west Kunlun Mts. to the Tarim Basin revealed the complex deep structure formed by continent-continent collision on the northern margin of the ... The explosive seismic sounding profile across the transition zone from the west Kunlun Mts. to the Tarim Basin revealed the complex deep structure formed by continent-continent collision on the northern margin of the Tibetan Plateau. The profile shows that the attitude of the Moho is in agreement with that of the crystalline basement in the Tarim Basin and the whole crust dips as a thick slate southwards with an angle from 5° to 7°. Meanwhile, the Moho depth increases from 40 km to 57 km within a distance of 150 km in the southern Tarim region, depicting the subduction of the crust of this region towards the west Kunlun Mts. The crust of the northern slope of the west Kunlun Mts. shows an evident compressed and shortened feature, that is, the basement is uplifted, the interface dips northwards and the Moho rises abruptly to become flat, so that the lower crust is as thick as 20 km. 展开更多
关键词 explosive seismic sounding Tarim Basin west Kunlun Mts crust structure Moho interface
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An experimental investigation on acoustic emission characteristics of sandstone rockburst with different moisture contents 被引量:9
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作者 SUN XiaoMing XU HuiChen +2 位作者 ZHENG LianGe HE ManChao GONG WeiLi 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2016年第10期1549-1558,共10页
Rockburst occurred frequently during deep mining in China. The mechanism of rockburst is very complicated and related to many factors. In order to investigate the influence of moisture contents of rockmass on rockburs... Rockburst occurred frequently during deep mining in China. The mechanism of rockburst is very complicated and related to many factors. In order to investigate the influence of moisture contents of rockmass on rockburst, we conducted a series of laboratory rockburst experiments of sandstone under three different moisture contents by the Modified True-Triaxial Apparatus (MTTA),in which the acoustic emission (AE) system was employed to monitor the internal damage of rock mass. A high-speed video camera was utilized to record the detail of rockburst. Based on the experimental results, the AE characteristics, such as AE count,AE energy, and AE frequency, were analyzed. The rockburst process, type, and indensity under different moisture contents were discussed. The research results show that with the increase of moisture contents, rock strength was soften, the elastic and the cumulative damage of the rock were reduced, resulting in a gradual decrease in AE cumulative counts and cumulative energy over the course of rockburst. This study provides an experimental basis and reference for better understanding to the rockburst mechanism and control. 展开更多
关键词 SANDSTONE ROCKBURST moisture contents acoustic emission mechanical characteristics
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