SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension cont...SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension containing nanosheet-like SAPO-34 seed. The latter played an important role in formation of SAPO-34 （CHA-type） with plate-like morphology. In addition, the yield of the product in the synthesis system containing seed suspension reached 97%, 15% higher than that obtained in the corre- sponding synthesis system without the seed suspension. Meanwhile, the plate-like SAPO-34 catalysts synthesized by this method exhibited higher selectivity to light olefins and longer lifetime in methanol-to-olefins （MTO） reaction than the traditional cubic SAPO-34 catalyst. This work provides a new technical route for green and efficient synthesis of SAPO-34 catalysts with improved MTO performance.展开更多
WC-8Co hardmetals with different proportions of prismatic WC grains and plate-like WC grains were directly produced through sintering the W-C-8Co ele- mental powder mixture which was fabricated by dielectric barrier d...WC-8Co hardmetals with different proportions of prismatic WC grains and plate-like WC grains were directly produced through sintering the W-C-8Co ele- mental powder mixture which was fabricated by dielectric barrier discharge plasma （DBDP）-assisted milling. The morphology of prepared WC-8Co hardmetals, geometry and the preferential orientation of plate-like WC were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM） analysis. The results demon- strate that the microstructure and mechanical properties of the sintered hardmetals are related to the morphology of W grain which is dependent on DBDP-milling time. The DBDP for 1 h （DBDP-1 h）-milled W-C-Co powder contains granular W particles that tend to form prismatic WC grains, while the DBDP for 3 h （DBDP-3 h）-milled powder contains lamellar W particles that generate plate-like WC grains. By adjusting the weight ratio of DBDP-1 h powder and DBDP-3 h powder in W-C-8Co mixture, the proportion of plate-like WC in the hardmetals can be controlled, and relatively high transverse rupture strength （TRS） is obtained as the proportion of plate-like WC grain in the hardmetals is about 35 % in present experimental condition.展开更多
Based on mode acoustic emission theory,the paper analyses the acoustic emission analog signal of thin steel plate using matching pursuit,then obtains the characteristics interpretation of the different frequency signa...Based on mode acoustic emission theory,the paper analyses the acoustic emission analog signal of thin steel plate using matching pursuit,then obtains the characteristics interpretation of the different frequency signal energy concentration degree; Combined with four-point arc positioning method,the papers researches the damage localization of the plate-like structure. Simulation experiment shows that this method can accurately detect and locate the damage. This can provide data support for further imaging research based on time reverse theory.展开更多
Lamb波具有传播距离远、衰减小等优点,能在板结构中实现大范围、高效率的损伤检测和监测,在无损检测和结构健康监测领域具有极大的应用潜力。针对板结构大范围健康监测问题,为了能周向一致地激励出模态单一Lamb波S0模态,提高缺陷成像能...Lamb波具有传播距离远、衰减小等优点,能在板结构中实现大范围、高效率的损伤检测和监测,在无损检测和结构健康监测领域具有极大的应用潜力。针对板结构大范围健康监测问题,为了能周向一致地激励出模态单一Lamb波S0模态,提高缺陷成像能力,基于磁致伸缩效应,设计并制作一种全向型S0模态磁致伸缩传感器,由印刷电路板线圈,圆柱磁铁,圆形镍片组成。试验验证研制的传感器能够在铝板中有效激励出单一的S0模态,并测试其频率响应特性以及全向性,结果表明设计传感器中心频率为365 k Hz,并具有较好的全向性。进一步利用研制的全向型S0模态磁致伸缩型传感器组成稀疏传感器阵列。采用自激自收的方式对铝板结构中缺陷进行检测。利用离散圆弧成像与数据融合算法相结合的方法对多组数据进行处理,消除常规的稀疏传感器阵列成像时对结构健康状况下的信号依赖,无需健康状况下的信号作为参考,实现了在板结构中缺陷的定位和成像。展开更多
文摘SAPO-34 catalyst with plate-like morphology was designed and synthesized for the first time, by the dry gel conversion method using cheap triethylamine as a structure-directing agent assisted with seed suspension containing nanosheet-like SAPO-34 seed. The latter played an important role in formation of SAPO-34 （CHA-type） with plate-like morphology. In addition, the yield of the product in the synthesis system containing seed suspension reached 97%, 15% higher than that obtained in the corre- sponding synthesis system without the seed suspension. Meanwhile, the plate-like SAPO-34 catalysts synthesized by this method exhibited higher selectivity to light olefins and longer lifetime in methanol-to-olefins （MTO） reaction than the traditional cubic SAPO-34 catalyst. This work provides a new technical route for green and efficient synthesis of SAPO-34 catalysts with improved MTO performance.
基金financially supported by the Guangdong Provincial Natural Science Foundation(No. 2014A030310395)the Fundamental Research Funds for the Central Universities(No.2014ZB0020)
文摘WC-8Co hardmetals with different proportions of prismatic WC grains and plate-like WC grains were directly produced through sintering the W-C-8Co ele- mental powder mixture which was fabricated by dielectric barrier discharge plasma （DBDP）-assisted milling. The morphology of prepared WC-8Co hardmetals, geometry and the preferential orientation of plate-like WC were investigated by X-ray diffraction （XRD） and scanning electron microscopy （SEM） analysis. The results demon- strate that the microstructure and mechanical properties of the sintered hardmetals are related to the morphology of W grain which is dependent on DBDP-milling time. The DBDP for 1 h （DBDP-1 h）-milled W-C-Co powder contains granular W particles that tend to form prismatic WC grains, while the DBDP for 3 h （DBDP-3 h）-milled powder contains lamellar W particles that generate plate-like WC grains. By adjusting the weight ratio of DBDP-1 h powder and DBDP-3 h powder in W-C-8Co mixture, the proportion of plate-like WC in the hardmetals can be controlled, and relatively high transverse rupture strength （TRS） is obtained as the proportion of plate-like WC grain in the hardmetals is about 35 % in present experimental condition.
基金supported by the Natural Science Foundation of Naval University of Engineering(under Grant No.HGDYDJJ13152)
文摘Based on mode acoustic emission theory,the paper analyses the acoustic emission analog signal of thin steel plate using matching pursuit,then obtains the characteristics interpretation of the different frequency signal energy concentration degree; Combined with four-point arc positioning method,the papers researches the damage localization of the plate-like structure. Simulation experiment shows that this method can accurately detect and locate the damage. This can provide data support for further imaging research based on time reverse theory.
文摘Lamb波具有传播距离远、衰减小等优点,能在板结构中实现大范围、高效率的损伤检测和监测,在无损检测和结构健康监测领域具有极大的应用潜力。针对板结构大范围健康监测问题,为了能周向一致地激励出模态单一Lamb波S0模态,提高缺陷成像能力,基于磁致伸缩效应,设计并制作一种全向型S0模态磁致伸缩传感器,由印刷电路板线圈,圆柱磁铁,圆形镍片组成。试验验证研制的传感器能够在铝板中有效激励出单一的S0模态,并测试其频率响应特性以及全向性,结果表明设计传感器中心频率为365 k Hz,并具有较好的全向性。进一步利用研制的全向型S0模态磁致伸缩型传感器组成稀疏传感器阵列。采用自激自收的方式对铝板结构中缺陷进行检测。利用离散圆弧成像与数据融合算法相结合的方法对多组数据进行处理,消除常规的稀疏传感器阵列成像时对结构健康状况下的信号依赖,无需健康状况下的信号作为参考,实现了在板结构中缺陷的定位和成像。
