W型潜坝作为一种新型的堰坝结构,不仅具有消能、护岸、分流和改善通航条件等功能,而且具有显著的生态功能。选取鲫鱼幼鱼为目标鱼类,研究不同粒径组成的W型潜坝的河流流速分布及对目标鱼类聚集的影响,探明W型潜坝的生境改良效果,为裁弯...W型潜坝作为一种新型的堰坝结构,不仅具有消能、护岸、分流和改善通航条件等功能,而且具有显著的生态功能。选取鲫鱼幼鱼为目标鱼类,研究不同粒径组成的W型潜坝的河流流速分布及对目标鱼类聚集的影响,探明W型潜坝的生境改良效果,为裁弯河段生态涵养区建设提供依据。研究结果表明不同粒径的W型潜坝作用下,[10,20]mm较大粒径组成的W型潜坝透水性更好,流速梯度小于小粒径组,流态多样性高。在流量0.09 m 3/s条件下,[10,20]mm粒径组成的W型潜坝鱼类聚集区域停留最多达到85次;[10,20]mm较大粒径组成的W型潜坝生境多样性高,可以为试验鱼提供更好的栖息和庇护场所。因此,在人工运河修建中裁弯河段生态涵养区建议选透水效果较好的大粒径潜坝方案。流态多样性指数与鱼类平均聚集度存在线性关系,可作为评价栖息地质量的依据,研究成果为河流生境异质性研究和生态优化设计提供理论支撑。展开更多
Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G...Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).展开更多
In a hard chromium electroplating process, a heat exchanger is employed to remove the heat produced from the high current intensity in an electroplating bath.Normally, a conventional U shape heat exchanger is installe...In a hard chromium electroplating process, a heat exchanger is employed to remove the heat produced from the high current intensity in an electroplating bath.Normally, a conventional U shape heat exchanger is installed in the bath, but it provides low heat removal.Thus, this study designs a novel W serpentine shape heat exchanger with identical heat transfer area to the conventional one for increasing heat removal performance.The performance of the heat exchange is tested with various flow velocities in a cross-section in range of 1.6 to 2.4 m·s^(-1).Mathematical models of this process have been formulated in order to simulate and evaluate the heat exchanger performance.The results show that the developed models give a good prediction of the plating solution and cooling water temperature, and the novel heat exchanger provides better results at any flow velocity.In addition, the W serpentine shape heat exchanger has been implemented in a real hard chromium electroplating plant.Actual data collected have shown that the new design gives higher heat removal performance compared with the U shape heat exchanger with identical heat transfer area; it removes more heat out of the process than the conventional one of about 23%.展开更多
This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied an...This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.展开更多
文摘W型潜坝作为一种新型的堰坝结构,不仅具有消能、护岸、分流和改善通航条件等功能,而且具有显著的生态功能。选取鲫鱼幼鱼为目标鱼类,研究不同粒径组成的W型潜坝的河流流速分布及对目标鱼类聚集的影响,探明W型潜坝的生境改良效果,为裁弯河段生态涵养区建设提供依据。研究结果表明不同粒径的W型潜坝作用下,[10,20]mm较大粒径组成的W型潜坝透水性更好,流速梯度小于小粒径组,流态多样性高。在流量0.09 m 3/s条件下,[10,20]mm粒径组成的W型潜坝鱼类聚集区域停留最多达到85次;[10,20]mm较大粒径组成的W型潜坝生境多样性高,可以为试验鱼提供更好的栖息和庇护场所。因此,在人工运河修建中裁弯河段生态涵养区建议选透水效果较好的大粒径潜坝方案。流态多样性指数与鱼类平均聚集度存在线性关系,可作为评价栖息地质量的依据,研究成果为河流生境异质性研究和生态优化设计提供理论支撑。
文摘Intergranular stress corrosion cracking (ISCC) of α-brass in neutral Mattsson's solution was found to be controlled by an unusual 'W'-shaped galvanic cell whose cathode is the grain boundary oxide film (G.B.0. film) and surface film and the anode is fresh metal at the cracked tip on both sides of the G.B.0. film. Redox reactions involved in the cell have been proposed here. According to this mdel, initidtion of ISCC is caused by the rupturing of surface film along grain boundaries, thus forming a galvanic cell. Propagation of ISCC resulted from alternate advances of G.B.0. film and dissolution on both sides of G.B.0. film caused by the effect of electrochemical reaction. This work developed an effective approach to investigate the embrittlement process at the tip of the crack, by increasing the length of the embrittlement region through constant strain test and distinguishing the morphology and the nature of the corrosion products by optical microscopy and scanning electron microscopy (SEH).
基金Supported by Thailand Research Fund(TRF)under The Royal Golden Jubilee Ph.D.Program(PHD/0158/2550)Chulalongkorn University(Contract No.RES_57_411_21_076)Chulalongkorn Academic Advancement into its 2nd Century Project
文摘In a hard chromium electroplating process, a heat exchanger is employed to remove the heat produced from the high current intensity in an electroplating bath.Normally, a conventional U shape heat exchanger is installed in the bath, but it provides low heat removal.Thus, this study designs a novel W serpentine shape heat exchanger with identical heat transfer area to the conventional one for increasing heat removal performance.The performance of the heat exchange is tested with various flow velocities in a cross-section in range of 1.6 to 2.4 m·s^(-1).Mathematical models of this process have been formulated in order to simulate and evaluate the heat exchanger performance.The results show that the developed models give a good prediction of the plating solution and cooling water temperature, and the novel heat exchanger provides better results at any flow velocity.In addition, the W serpentine shape heat exchanger has been implemented in a real hard chromium electroplating plant.Actual data collected have shown that the new design gives higher heat removal performance compared with the U shape heat exchanger with identical heat transfer area; it removes more heat out of the process than the conventional one of about 23%.
文摘This study proposes a three-dimensional (3D) particle image velocimetry (PIV) method using W- shaped light sheet and color PIV with a digital SLR camera. The uncertainty of the velocity measurement was also studied and it was acceptable. The spatial resolution of the z-direction has much room for improvement by increasing the number of cameras. When applied to the velocity distribution measurement of a thermal vertical buoyant plume, the proposed 3D PIV method is found to be very effective for studying thermal structures and well suited for measuring the airflow velocity field.
