The O-ring in the rotary dynamic sealing system of gas meters should have outstanding long-term sealing performance under the conditions of high and low temperature,which can ensure the safety of gas meters.In this pa...The O-ring in the rotary dynamic sealing system of gas meters should have outstanding long-term sealing performance under the conditions of high and low temperature,which can ensure the safety of gas meters.In this paper,based on the O-ring sealing mechanism,taking the compression set as the main sealing index,a finite element simulation method is used to analyze the failure charac-teristics under different conditions according to the constitutive relation of nitrile rubber.Then,using the orthogonal test method for the O-ring sealing performance index,the main factors which affect the law of long-term test are analysed,and the orthogonal regression mathematical model that can predict the compression set is obtained.Finally,the O-ring is improved according to the model,and the test results show that the performance of the new O-rings with high and low temperature resistance is greatly improved and meets the expected target requirements.展开更多
The recovery of compression set (RS) of wood after dry heating or steam treatment mainly depends on the temperature and time of treatment. For quantitative elucidation, a graph of intermediate RS was built with temper...The recovery of compression set (RS) of wood after dry heating or steam treatment mainly depends on the temperature and time of treatment. For quantitative elucidation, a graph of intermediate RS was built with temperature (T) and time (t) as coordinates. In this graph (abbreviated as T-t planum), a series of curves of RS were created. This leads to a conclusion that same RS can be obtained by numerous different pathways. Further research on pathway equivalency based on T-t planum indicates that a low RS of 10% can be achieved definitely by different combinations of time and temperature. However, the fixation mechanism varies at different temperatures. On the equivalent pathways of higher recovery, the influence of temperature must be taken into consideration. The actual routes must be somewhat modified to achieve an expected result. This makes it possible for us to work out a best fixation pathway among all the possibilities, to eliminate the impact of heat on the mechanical properties of wood.展开更多
in order to increase its hardness and gravity as well as dimension stability, the technology of hotcompressing on P8ulownla wood was studied. The main factors of affecting the spring back of the compressedPaulownis sa...in order to increase its hardness and gravity as well as dimension stability, the technology of hotcompressing on P8ulownla wood was studied. The main factors of affecting the spring back of the compressedPaulownis samples were discussed. It was discovered that every factor in the experiment had obvious effects onwood hardness and dimension stability of compressed wood. When the MC (Moisture Content) of experimentalspecimens was 13.89%, it was useful to spray water on the surface of samples before hot pressing. The best reSult was the recovery of compression set could decrease from 90.69O/O of untreated wood to 45.51 % of soakingspecimens into PF (Phenol Formaldehyde) water solution. The hot pressing time was 8 min at 190℃.展开更多
The phosphorus slag（PS） can be used as a supplementary cementitious material due to its potential hydrating activity. However, its usage has been limited by its adverse effects, including prolonged setting and lower...The phosphorus slag（PS） can be used as a supplementary cementitious material due to its potential hydrating activity. However, its usage has been limited by its adverse effects, including prolonged setting and lowered early-stage strength. In this study, we achieved ultrafine granulation of PS using wetmilling（reducing d50 to as low as 2.02 μm） in order to increase its activity, and examined the physico-chemical properties of the resulting materials, including particle-size distribution, slurry pH, zeta potential, and activity index, as well as how their replacement level and granularity affect the setting time and mechanical performance of PS-cement mixture systems. The results suggested that as the granularity increases, there are significant boosts in the uniformity of particle sizes, slurry pH, and activity index, and the effects on cement paste, including setting times, and early-and late-stage strengths, are significantly mitigated. When d（50）=2.02 μm, the slurry becomes strongly alkaline（pH=12.16） compared to the initial d（50）=20.75 μm（pH=9.49）, and the activity is increased by 73%; when used at 40% replacement, the PS-cement mixture system can reach a 28 d compressive strength of 93.2 MPa, 36% higher than that of the pure cement control group.展开更多
As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, Li Al-LDHs was obtained by a hydrothermal method. In order to ...As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, Li Al-LDHs was obtained by a hydrothermal method. In order to investigate the effects of Li Al-LDHs on the early hydration of calcium sulphoaluminate（CSA） cement paste, compressive strength, setting time and hydration heat were tested while X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, scaning electron microscopy（SEM） and differential scanning calorimetry（DSC） analysis were employed. The results indicated that Li Al-LDHs could significantly improve the early compressive strength and shorten the setting time of calcium sulphoaluminate cement paste with 3 wt% concentration. Besides, the hydration exothermic rate within 5h was accelerated with increasing Li Al-LDHs content. Moreover, the addition of Li Al-LDHs did not result in the formation of a new phase, but increased the quantity of hydration products providing higher compressive strength, shorter setting time and denser microstructure.展开更多
Compressional region usually forms complex thrust faults system, which is difficult to identify using traditional migration profiles. The successful application of three-dimensional（3D） seismic attributes analysis g...Compressional region usually forms complex thrust faults system, which is difficult to identify using traditional migration profiles. The successful application of three-dimensional（3D） seismic attributes analysis greatly reduces the difficulty, and improves the accuracy and efficiency of seismic interpretation and structural analysis. In this paper, we took Qiongxi area in the compressional region of western Sichuan as an example, using two 3D seismic attributes, coherence and instantaneous phase, to identify fault assemblages and variations both vertically and laterally. The results show that the study area mainly consists of NS-, NE- and NEE-trending faults. The NS-trending faults are the largest and have a component of sinistral slip controlling the formation of NEE-trending faults, while the NE-trending faults are intermediate in scale, formed earlier and were cut by the NS-trending faults. Our results demonstrate that using seismic attributes for structural analysis have the following advantages：（1） more details of major fault zones,（2） highlighting minor faults which are hardly traced in seismic migration cube, and（3） easier acquisition of accurate fault systems. The application of seismic attributes provides a new idea for deciphering fine and complicated structures, and will significantly contribute to the development of objective and precise geological interpretation in the future.展开更多
This study investigated the effect of weight percent gain （WPG） and compression set on the crystallity of compressed poplar wood. Tests were conducted to determine the mechanism of compressed wood set. The samples o...This study investigated the effect of weight percent gain （WPG） and compression set on the crystallity of compressed poplar wood. Tests were conducted to determine the mechanism of compressed wood set. The samples of 1-72 Poplar were treated with a PF resin of water-solubility and low molecular weight. Then the air-dried samples were hot-pressed to a certain thickness. Finally the specimens were obtained from the compressed samples and scanned with an X-ray diffractometer. Results show that before press the crystallity of the inner layer is lower than that of the outer layer, and at press the difference of the crystallity between the outer layer and the inner layer will slowly disappear and finally the crystallity of the inner layer exceeds that of the outer layer; with the increasing compression set the crystallity decreases, and there is a big decrease; the crystallity difference between two layers happens because of compression set gradient, WPG difference or the joint effect.展开更多
基金Supported by the National Key Research and Development Program of China(No.2018YFC0808902).
文摘The O-ring in the rotary dynamic sealing system of gas meters should have outstanding long-term sealing performance under the conditions of high and low temperature,which can ensure the safety of gas meters.In this paper,based on the O-ring sealing mechanism,taking the compression set as the main sealing index,a finite element simulation method is used to analyze the failure charac-teristics under different conditions according to the constitutive relation of nitrile rubber.Then,using the orthogonal test method for the O-ring sealing performance index,the main factors which affect the law of long-term test are analysed,and the orthogonal regression mathematical model that can predict the compression set is obtained.Finally,the O-ring is improved according to the model,and the test results show that the performance of the new O-rings with high and low temperature resistance is greatly improved and meets the expected target requirements.
基金the National Natural Science Foundation of China (Grant No. 30070606) and by Association of International Education of Japan
文摘The recovery of compression set (RS) of wood after dry heating or steam treatment mainly depends on the temperature and time of treatment. For quantitative elucidation, a graph of intermediate RS was built with temperature (T) and time (t) as coordinates. In this graph (abbreviated as T-t planum), a series of curves of RS were created. This leads to a conclusion that same RS can be obtained by numerous different pathways. Further research on pathway equivalency based on T-t planum indicates that a low RS of 10% can be achieved definitely by different combinations of time and temperature. However, the fixation mechanism varies at different temperatures. On the equivalent pathways of higher recovery, the influence of temperature must be taken into consideration. The actual routes must be somewhat modified to achieve an expected result. This makes it possible for us to work out a best fixation pathway among all the possibilities, to eliminate the impact of heat on the mechanical properties of wood.
文摘in order to increase its hardness and gravity as well as dimension stability, the technology of hotcompressing on P8ulownla wood was studied. The main factors of affecting the spring back of the compressedPaulownis samples were discussed. It was discovered that every factor in the experiment had obvious effects onwood hardness and dimension stability of compressed wood. When the MC (Moisture Content) of experimentalspecimens was 13.89%, it was useful to spray water on the surface of samples before hot pressing. The best reSult was the recovery of compression set could decrease from 90.69O/O of untreated wood to 45.51 % of soakingspecimens into PF (Phenol Formaldehyde) water solution. The hot pressing time was 8 min at 190℃.
基金Funded by National Natural Science Foundation of China(No.51372076)the Technology Innovation Major Project of Hubei Province(No.2017ACA178)the Science and Technology Support Program of Hubei Province(No.2015BCA244)
文摘The phosphorus slag（PS） can be used as a supplementary cementitious material due to its potential hydrating activity. However, its usage has been limited by its adverse effects, including prolonged setting and lowered early-stage strength. In this study, we achieved ultrafine granulation of PS using wetmilling（reducing d50 to as low as 2.02 μm） in order to increase its activity, and examined the physico-chemical properties of the resulting materials, including particle-size distribution, slurry pH, zeta potential, and activity index, as well as how their replacement level and granularity affect the setting time and mechanical performance of PS-cement mixture systems. The results suggested that as the granularity increases, there are significant boosts in the uniformity of particle sizes, slurry pH, and activity index, and the effects on cement paste, including setting times, and early-and late-stage strengths, are significantly mitigated. When d（50）=2.02 μm, the slurry becomes strongly alkaline（pH=12.16） compared to the initial d（50）=20.75 μm（pH=9.49）, and the activity is increased by 73%; when used at 40% replacement, the PS-cement mixture system can reach a 28 d compressive strength of 93.2 MPa, 36% higher than that of the pure cement control group.
基金Funded by the National Natural Sciense Foundation of China(No.51272068)
文摘As a 3D micro-nano material, layered double hydroxides have been widely used in many fields, especially for reinforced composite materials. In this paper, Li Al-LDHs was obtained by a hydrothermal method. In order to investigate the effects of Li Al-LDHs on the early hydration of calcium sulphoaluminate（CSA） cement paste, compressive strength, setting time and hydration heat were tested while X-ray diffraction（XRD）, Fourier transform infrared spectroscopy（FT-IR）, scaning electron microscopy（SEM） and differential scanning calorimetry（DSC） analysis were employed. The results indicated that Li Al-LDHs could significantly improve the early compressive strength and shorten the setting time of calcium sulphoaluminate cement paste with 3 wt% concentration. Besides, the hydration exothermic rate within 5h was accelerated with increasing Li Al-LDHs content. Moreover, the addition of Li Al-LDHs did not result in the formation of a new phase, but increased the quantity of hydration products providing higher compressive strength, shorter setting time and denser microstructure.
基金supported by the Major National S & T Program (No. 2008ZX050009-001-01)
文摘Compressional region usually forms complex thrust faults system, which is difficult to identify using traditional migration profiles. The successful application of three-dimensional（3D） seismic attributes analysis greatly reduces the difficulty, and improves the accuracy and efficiency of seismic interpretation and structural analysis. In this paper, we took Qiongxi area in the compressional region of western Sichuan as an example, using two 3D seismic attributes, coherence and instantaneous phase, to identify fault assemblages and variations both vertically and laterally. The results show that the study area mainly consists of NS-, NE- and NEE-trending faults. The NS-trending faults are the largest and have a component of sinistral slip controlling the formation of NEE-trending faults, while the NE-trending faults are intermediate in scale, formed earlier and were cut by the NS-trending faults. Our results demonstrate that using seismic attributes for structural analysis have the following advantages：（1） more details of major fault zones,（2） highlighting minor faults which are hardly traced in seismic migration cube, and（3） easier acquisition of accurate fault systems. The application of seismic attributes provides a new idea for deciphering fine and complicated structures, and will significantly contribute to the development of objective and precise geological interpretation in the future.
文摘This study investigated the effect of weight percent gain （WPG） and compression set on the crystallity of compressed poplar wood. Tests were conducted to determine the mechanism of compressed wood set. The samples of 1-72 Poplar were treated with a PF resin of water-solubility and low molecular weight. Then the air-dried samples were hot-pressed to a certain thickness. Finally the specimens were obtained from the compressed samples and scanned with an X-ray diffractometer. Results show that before press the crystallity of the inner layer is lower than that of the outer layer, and at press the difference of the crystallity between the outer layer and the inner layer will slowly disappear and finally the crystallity of the inner layer exceeds that of the outer layer; with the increasing compression set the crystallity decreases, and there is a big decrease; the crystallity difference between two layers happens because of compression set gradient, WPG difference or the joint effect.
