The application of railway wheel noise compensation method is considered. The effect can be obtained by shift a pair of usual parallel rail joints on a pair of offset rail joints, for example, the right rail joint is ...The application of railway wheel noise compensation method is considered. The effect can be obtained by shift a pair of usual parallel rail joints on a pair of offset rail joints, for example, the right rail joint is shifted concerning the left rail joint on the certain distance. The distance is depend on the speed of train and promotes the correlation interconnection between excited acoustical pulses. The intensity wheel knock spectrograms corresponding of different distance between rail joints registered by the microphone are estimated. The spectrograms considerably differed from each other in low frequency band are analyzed. The result of practical using the acoustic noise compensation method is proved.展开更多
This study investigated the effects of SIRT1 gene knock-out on osteoarthritis in mice, and the possible roles of SREBP2 protein and the PI3K/AKT signaling pathway in the effects. Mice were randomly divided into a norm...This study investigated the effects of SIRT1 gene knock-out on osteoarthritis in mice, and the possible roles of SREBP2 protein and the PI3K/AKT signaling pathway in the effects. Mice were randomly divided into a normal group and a SIRT1 gene knock-out group（6 mice in each group）. In these groups, one side of the knee anterior cruciate ligament was traversed, and the ipsilateral medial meniscus was cut to establish an osteoarthritis model of knee joint. The countralateral synovial bursa was cut out, serving as controls. The knee joint specimens were then divided into four groups： SIRT1^（＋/＋） control group（group A, n=6）; SIRT1^（＋/＋） osteoarthritis group（group B, n=6）; SIRT1^（–/–） control group（group C, n=6）; SIRT1^（–/–） osteoarthritis group（group D, n=6）. HE staining, Masson staining, Safranin O-Fast Green staining and Van Gieson staining were used to observe the morphological changes in the articular cartilage of the knee. Immunohistochemical staining was employed to detect the expression of SIRT1, SREBP2, VEGF, AKT, HMGCR and type Ⅱ collagen proteins. SA-β-gal staining was utilized to evaluate chondrocyte aging. The results showed clear knee joint cartilage destruction and degeneration in the SIRT1^（–/–） osteoarthritis group. The tidal line was twisted and displaced anteriorly. Type Ⅱ collagen was destroyed and distributed unevenly. Compared with the SIRT1^（＋/＋） osteoarthritis group and SIRT1^（–/–） control group, SIRT1 protein expression was not obviously changed in the SIRT1^（–/–） osteoarthritis group（P〉0.05）, while the expression levels of the SREBP2, VEGF and HMGCR proteins were significantly increased（P〈0.05） and the levels of AKT and type Ⅱ collagen proteins were significantly decreased（P〈0.05）. SIRT1 gene knock-out may aggravate cartilage degeneration in osteoarthritis by activating the SREBP2 protein-mediated PI3K/AKT signalling pathway, suggesting that SIRT1 gene may play a protective role against osteoarthritis.展开更多
Based on the loading conditions of engine, applying difference method to solve the hydrodynamic lubrication equation of piston skirt movement, the force acting on piston skirt and the moment on wrist pin were obtained...Based on the loading conditions of engine, applying difference method to solve the hydrodynamic lubrication equation of piston skirt movement, the force acting on piston skirt and the moment on wrist pin were obtained. A computer program for simulating the piston second order motion was conducted to calculate the lateral motion of the upper part and the bottom part of piston skirts of the engine of automotive model CA1091. From the simulated result, the maximal impacting phase and the maximal impacting region of the piston were obtained. The result can be used for designing engine, diagnosing the noise of piston knocking cylinder wall and explaining many practical fault phenomena in theory.展开更多
Knock in spark-ignition(SI)engines severely limits engine performance and thermal efficiency.The researches on knock of downsized SI engine have mainly focused on structural design,performance optimization and advance...Knock in spark-ignition(SI)engines severely limits engine performance and thermal efficiency.The researches on knock of downsized SI engine have mainly focused on structural design,performance optimization and advanced combustion modes,however there is little for simulation study on the effect of cooled exhaust gas recirculation(EGR)combined with downsizing technologies on SI engine performance.On the basis of mean pressure and oscillating pressure during combustion process,the effect of different levels of cooled EGR ratio,supercharging and compression ratio on engine dynamic and knock characteristic is researched with three-dimensional KIVA-3V program coupled with pressure wave equation.The cylinder pressure,combustion temperature,ignition delay timing,combustion duration,maximum mean pressure,and maximum oscillating pressure at different initial conditions are discussed and analyzed to investigate potential approaches to inhibiting engine knock while improving power output.The calculation results of the effect of just cooled EGR on knock characteristic show that appropriate levels of cooled EGR ratio can effectively suppress cylinder high-frequency pressure oscillations without obvious decrease in mean pressure.Analysis of the synergistic effect of cooled EGR,supercharging and compression ratio on knock characteristic indicates that under the condition of high supercharging and compression ratio,several times more cooled EGR ratio than that under the original condition is necessarily utilized to suppress knock occurrence effectively.The proposed method of synergistic effect of cooled EGR and downsizing technologies on knock characteristic,analyzed from the aspects of mean pressure and oscillating pressure,is an effective way to study downsized SI engine knock and provides knock inhibition approaches in practical engineering.展开更多
This study aimed to compare the efficiencies of clustered regulatory interspaced short palindromic repeat（CRISPR）/Cas9-mediated gene knock-ins with zinc finger nucleases（ZFNs） and transcription activator-like effe...This study aimed to compare the efficiencies of clustered regulatory interspaced short palindromic repeat（CRISPR）/Cas9-mediated gene knock-ins with zinc finger nucleases（ZFNs） and transcription activator-like effector nucleases（TALENs） in bovine and dairy goat fetal fibroblasts. To test the knock-in efficiency, a set of ZFNs and CRISPR/Cas9 plasmids were designed to edit the bovine myostatin（MSTN） gene at exon 2, while a set of TALENs and CRISPR/Cas9 plasmids were designed for editing the dairy goat β-casein gene at exon 2. Donor plasmids utilizing the ZFNs, TALENs, and CRISPR/Cas9 cutting sites were constructed in theGFP-PGK-Neo R plasmid background, including a 5′ and 3′ homologous arm flanking the genes humanized Fat-1（h Fat-1） or enhanced green fluorescent protein（eGFP）. Subsequently, the ZFNs, TALENs, or CRISPR/Cas9 and thehFat-1 or eGFP plasmids were co-transfected by electroporation into bovine and dairy goat fetal fibroblasts. After G418（Geneticin） selection, single cells were obtained by mouth pipetting, flow cytometry or a cell shove. The gene knock-in events were screened by PCR across the homologous arms. The results showed that in bovine fetal fibrobalsts, the efficiencies of ZFNs-mediated eGFP andhFat-1 gene knock-ins were 13.68 and 0%, respectively. The efficiencies of CRISPR/Cas9-mediated eGFP andhFat-1 gene knock-ins were 77.02 and 79.01%, respectively. The eGFP gene knock-in efficiency using CRISPR/Cas9 was about 5.6 times higher than when using the ZFNs gene editing system. Additionally, thehFat-1 gene knock-in was only obtained when using the CRISPR/Cas9 system. The difference of knockin efficiencies between the ZFNs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. In the dairy goat fetal fibroblasts, the efficiencies of TALENs-mediated eGFP andhFat-1 gene knock-ins were 32.35 and 26.47%, respectively. Theefficiencies of eGFP and hFat-1 gene knock-ins using CRISPR/Cas9 were 70.37 and 74.29%, respectively. The knock-in efficiencies difference between the TALENs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. This study demonstrated that CRISPR/Cas9 was more efficient at gene knock-ins in domesticated animal cells than ZFNs and TALENs. The CRISPR/Cas9 technology offers a new era of precise gene editing in domesticated animal cell lines.展开更多
The present work used a methane-air mixture chemical kinetics scheme consisting of 119 elementary reaction steps and 41 chemical species to develop a simplified combustion model for prediction of the knock in dual fue...The present work used a methane-air mixture chemical kinetics scheme consisting of 119 elementary reaction steps and 41 chemical species to develop a simplified combustion model for prediction of the knock in dual fuel engines. Calculated values by the model for natural gas operation showed good agreement with corresponding experimental values over a broad range of operating conditions.展开更多
Experiments were conducted on a diesel-methanol dual-fuel(DMDF)engine modified by a six-cylinder,turbocharged,inter-cooled diesel engine.According to the number of diesel injection,the experiments are divided to two p...Experiments were conducted on a diesel-methanol dual-fuel(DMDF)engine modified by a six-cylinder,turbocharged,inter-cooled diesel engine.According to the number of diesel injection,the experiments are divided to two parts:the single injectionmode and double injectionmode.The results show that,at the double injectionmode,themaximumof pressure rise rate is small and the engine runs smoothly,however,knock still occurswhen the cocombustion ratio(CCR)is big enough.Under knock status,the power density of the block vibration concentrating at some special frequencies rises dramatically,and the special frequency of single injection mode(about 4.1 kHz)is lower than that of double injection mode(7–9 kHz).The cylinder pressure oscillations of knock status are very different fromthe non-knock status.Under knock status,cylinder pressure oscillations become more concentrated and fiercer at some special frequencies,and the same as the block vibration.The special frequency of single injection mode(3–6 kHz)is lower than that of double injection mode(above 9 kHz).展开更多
海上拖航合同中的Knock For Knock条款的效力在实践中一直存在争议。本文通过分析《海商法》第162条,结合Knock For Knock条款的性质进行讨论,得出结论《海商法》第162条可以作为订立Knock For Knock条款的依据,但是不能作为该条款在任...海上拖航合同中的Knock For Knock条款的效力在实践中一直存在争议。本文通过分析《海商法》第162条,结合Knock For Knock条款的性质进行讨论,得出结论《海商法》第162条可以作为订立Knock For Knock条款的依据,但是不能作为该条款在任何情形下均有效的依据。并且通过对Knock For Knock条款效力的进一步探讨,可知海上拖航中的承拖方不得以该条款对抗被拖方提出的由于承拖方的故意或重大过失行为造成其损失的赔偿请求。除此之外,本文将借鉴国外判例,结合我国国情,提出减少Knock For Knock条款实践纠纷的建议。展开更多
文摘The application of railway wheel noise compensation method is considered. The effect can be obtained by shift a pair of usual parallel rail joints on a pair of offset rail joints, for example, the right rail joint is shifted concerning the left rail joint on the certain distance. The distance is depend on the speed of train and promotes the correlation interconnection between excited acoustical pulses. The intensity wheel knock spectrograms corresponding of different distance between rail joints registered by the microphone are estimated. The spectrograms considerably differed from each other in low frequency band are analyzed. The result of practical using the acoustic noise compensation method is proved.
基金supported by grants from the National Natural Science Foundation of China(No.81272032)the Research and Development Projects of Shenzhen of China(Nos.JCYJ20150403091443275)
文摘This study investigated the effects of SIRT1 gene knock-out on osteoarthritis in mice, and the possible roles of SREBP2 protein and the PI3K/AKT signaling pathway in the effects. Mice were randomly divided into a normal group and a SIRT1 gene knock-out group（6 mice in each group）. In these groups, one side of the knee anterior cruciate ligament was traversed, and the ipsilateral medial meniscus was cut to establish an osteoarthritis model of knee joint. The countralateral synovial bursa was cut out, serving as controls. The knee joint specimens were then divided into four groups： SIRT1^（＋/＋） control group（group A, n=6）; SIRT1^（＋/＋） osteoarthritis group（group B, n=6）; SIRT1^（–/–） control group（group C, n=6）; SIRT1^（–/–） osteoarthritis group（group D, n=6）. HE staining, Masson staining, Safranin O-Fast Green staining and Van Gieson staining were used to observe the morphological changes in the articular cartilage of the knee. Immunohistochemical staining was employed to detect the expression of SIRT1, SREBP2, VEGF, AKT, HMGCR and type Ⅱ collagen proteins. SA-β-gal staining was utilized to evaluate chondrocyte aging. The results showed clear knee joint cartilage destruction and degeneration in the SIRT1^（–/–） osteoarthritis group. The tidal line was twisted and displaced anteriorly. Type Ⅱ collagen was destroyed and distributed unevenly. Compared with the SIRT1^（＋/＋） osteoarthritis group and SIRT1^（–/–） control group, SIRT1 protein expression was not obviously changed in the SIRT1^（–/–） osteoarthritis group（P〉0.05）, while the expression levels of the SREBP2, VEGF and HMGCR proteins were significantly increased（P〈0.05） and the levels of AKT and type Ⅱ collagen proteins were significantly decreased（P〈0.05）. SIRT1 gene knock-out may aggravate cartilage degeneration in osteoarthritis by activating the SREBP2 protein-mediated PI3K/AKT signalling pathway, suggesting that SIRT1 gene may play a protective role against osteoarthritis.
文摘Based on the loading conditions of engine, applying difference method to solve the hydrodynamic lubrication equation of piston skirt movement, the force acting on piston skirt and the moment on wrist pin were obtained. A computer program for simulating the piston second order motion was conducted to calculate the lateral motion of the upper part and the bottom part of piston skirts of the engine of automotive model CA1091. From the simulated result, the maximal impacting phase and the maximal impacting region of the piston were obtained. The result can be used for designing engine, diagnosing the noise of piston knocking cylinder wall and explaining many practical fault phenomena in theory.
基金supported by National Natural Science Foundation of China(Grant No.51176138)Tianjin Municipal Natural Science Foundation of China(Grant No.12TJZDTJ28800)
文摘Knock in spark-ignition(SI)engines severely limits engine performance and thermal efficiency.The researches on knock of downsized SI engine have mainly focused on structural design,performance optimization and advanced combustion modes,however there is little for simulation study on the effect of cooled exhaust gas recirculation(EGR)combined with downsizing technologies on SI engine performance.On the basis of mean pressure and oscillating pressure during combustion process,the effect of different levels of cooled EGR ratio,supercharging and compression ratio on engine dynamic and knock characteristic is researched with three-dimensional KIVA-3V program coupled with pressure wave equation.The cylinder pressure,combustion temperature,ignition delay timing,combustion duration,maximum mean pressure,and maximum oscillating pressure at different initial conditions are discussed and analyzed to investigate potential approaches to inhibiting engine knock while improving power output.The calculation results of the effect of just cooled EGR on knock characteristic show that appropriate levels of cooled EGR ratio can effectively suppress cylinder high-frequency pressure oscillations without obvious decrease in mean pressure.Analysis of the synergistic effect of cooled EGR,supercharging and compression ratio on knock characteristic indicates that under the condition of high supercharging and compression ratio,several times more cooled EGR ratio than that under the original condition is necessarily utilized to suppress knock occurrence effectively.The proposed method of synergistic effect of cooled EGR and downsizing technologies on knock characteristic,analyzed from the aspects of mean pressure and oscillating pressure,is an effective way to study downsized SI engine knock and provides knock inhibition approaches in practical engineering.
基金supported by the National Transgenic Project of China (2016ZX08010001-002)the National Natural Science Foundation of China (81471001)+1 种基金the Inner Mongolia Science and Technology Program, China (201502073)the National 863 Prgram of China (2009AA10Z111)
文摘This study aimed to compare the efficiencies of clustered regulatory interspaced short palindromic repeat（CRISPR）/Cas9-mediated gene knock-ins with zinc finger nucleases（ZFNs） and transcription activator-like effector nucleases（TALENs） in bovine and dairy goat fetal fibroblasts. To test the knock-in efficiency, a set of ZFNs and CRISPR/Cas9 plasmids were designed to edit the bovine myostatin（MSTN） gene at exon 2, while a set of TALENs and CRISPR/Cas9 plasmids were designed for editing the dairy goat β-casein gene at exon 2. Donor plasmids utilizing the ZFNs, TALENs, and CRISPR/Cas9 cutting sites were constructed in theGFP-PGK-Neo R plasmid background, including a 5′ and 3′ homologous arm flanking the genes humanized Fat-1（h Fat-1） or enhanced green fluorescent protein（eGFP）. Subsequently, the ZFNs, TALENs, or CRISPR/Cas9 and thehFat-1 or eGFP plasmids were co-transfected by electroporation into bovine and dairy goat fetal fibroblasts. After G418（Geneticin） selection, single cells were obtained by mouth pipetting, flow cytometry or a cell shove. The gene knock-in events were screened by PCR across the homologous arms. The results showed that in bovine fetal fibrobalsts, the efficiencies of ZFNs-mediated eGFP andhFat-1 gene knock-ins were 13.68 and 0%, respectively. The efficiencies of CRISPR/Cas9-mediated eGFP andhFat-1 gene knock-ins were 77.02 and 79.01%, respectively. The eGFP gene knock-in efficiency using CRISPR/Cas9 was about 5.6 times higher than when using the ZFNs gene editing system. Additionally, thehFat-1 gene knock-in was only obtained when using the CRISPR/Cas9 system. The difference of knockin efficiencies between the ZFNs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. In the dairy goat fetal fibroblasts, the efficiencies of TALENs-mediated eGFP andhFat-1 gene knock-ins were 32.35 and 26.47%, respectively. Theefficiencies of eGFP and hFat-1 gene knock-ins using CRISPR/Cas9 were 70.37 and 74.29%, respectively. The knock-in efficiencies difference between the TALENs and CRISPR/Cas9 systems were extremely significant（P〈0.01）. This study demonstrated that CRISPR/Cas9 was more efficient at gene knock-ins in domesticated animal cells than ZFNs and TALENs. The CRISPR/Cas9 technology offers a new era of precise gene editing in domesticated animal cell lines.
文摘The present work used a methane-air mixture chemical kinetics scheme consisting of 119 elementary reaction steps and 41 chemical species to develop a simplified combustion model for prediction of the knock in dual fuel engines. Calculated values by the model for natural gas operation showed good agreement with corresponding experimental values over a broad range of operating conditions.
基金funded by the Science Research Project of State Grid Shaanxi Electric Power Company(5226 KY22001J)Yulin Science and Technology Planning Project(CXY-2020-024)+1 种基金Natural Science Basic Research Plan of Shaanxi(2018JQ5115,2020JM-243)the Special Fund for Basic Scientific Research of Central Colleges,Chang’an University(2018JQ5115).
文摘Experiments were conducted on a diesel-methanol dual-fuel(DMDF)engine modified by a six-cylinder,turbocharged,inter-cooled diesel engine.According to the number of diesel injection,the experiments are divided to two parts:the single injectionmode and double injectionmode.The results show that,at the double injectionmode,themaximumof pressure rise rate is small and the engine runs smoothly,however,knock still occurswhen the cocombustion ratio(CCR)is big enough.Under knock status,the power density of the block vibration concentrating at some special frequencies rises dramatically,and the special frequency of single injection mode(about 4.1 kHz)is lower than that of double injection mode(7–9 kHz).The cylinder pressure oscillations of knock status are very different fromthe non-knock status.Under knock status,cylinder pressure oscillations become more concentrated and fiercer at some special frequencies,and the same as the block vibration.The special frequency of single injection mode(3–6 kHz)is lower than that of double injection mode(above 9 kHz).
文摘海上拖航合同中的Knock For Knock条款的效力在实践中一直存在争议。本文通过分析《海商法》第162条,结合Knock For Knock条款的性质进行讨论,得出结论《海商法》第162条可以作为订立Knock For Knock条款的依据,但是不能作为该条款在任何情形下均有效的依据。并且通过对Knock For Knock条款效力的进一步探讨,可知海上拖航中的承拖方不得以该条款对抗被拖方提出的由于承拖方的故意或重大过失行为造成其损失的赔偿请求。除此之外,本文将借鉴国外判例,结合我国国情,提出减少Knock For Knock条款实践纠纷的建议。
