In 2013,cancer immunotherapy led the annual breakthroughs in Science.In fact,immunotherapy is one of the hotspots in cancer therapy,and can date back to the Coley vaccine in 1891.Advances in biotechnology and bio-engi...In 2013,cancer immunotherapy led the annual breakthroughs in Science.In fact,immunotherapy is one of the hotspots in cancer therapy,and can date back to the Coley vaccine in 1891.Advances in biotechnology and bio-engineering,especially research and development（R＆D）in the fields of therapeutic antibodies,checkpoint inhibitors,and engineered T cells,helped overcome the problems in tumor therapies,leading to increasing research focus on cancer immunotherapy.展开更多
某客车70 km/h出现轰鸣噪声,严重影响乘坐舒适性。通过声振测试和声学仿真方法对轰鸣原因进行了研究,确定了轰鸣噪声是传动轴激励频率与车内声腔模态频率耦合引起。通过优化传动轴的剩余不平衡量,降低传动轴激励,消弱车内声振耦合作用...某客车70 km/h出现轰鸣噪声,严重影响乘坐舒适性。通过声振测试和声学仿真方法对轰鸣原因进行了研究,确定了轰鸣噪声是传动轴激励频率与车内声腔模态频率耦合引起。通过优化传动轴的剩余不平衡量,降低传动轴激励,消弱车内声振耦合作用。试验结果表明,车内轰鸣噪声得到明显改善,A计权声压级降低了1.45 d B(A),C计权声压级降低了6.77 d B(C)。展开更多
The sound-producing mechanism of booming sand has long been a pending problem in the blown sand physics. Based on the earlier researches, the authors collected some silent sand samples from Teng- ger Desert, Australia...The sound-producing mechanism of booming sand has long been a pending problem in the blown sand physics. Based on the earlier researches, the authors collected some silent sand samples from Teng- ger Desert, Australian Desert, Kuwait Desert, beaches of Hainan Island and Japanese coast as well as the soundless booming sand samples from the Mingsha Mountain in Dunhuang to make washing ex- periments. In the meantime the chemical corrosion experiment of glass micro-spheres, surface coating experiment and SEM examination were also conducted. The experimental results show that the sound production of booming sand seems to have nothing to do with the presence of SiO2 gel on the surface of sand grains and unrelated to the surface chemical composition of sand grains but is related to the resonance cavities formed by porous (pit-like) physical structure resulting from a number of factors such as wind erosion, water erosion, chemical corrosion and SiO2 gel deposition, etc. Its resonance mechanism is similar to that of Hemholz resonance cavity. Under the action of external forces, nu- merous spherical and sand grains with smooth surface and porous surface are set in motion and rub with each other to produce extremely weak vibration sound and then become audible sound by human ears through the magnification of surface cavity resonance. However the booming sands may lose their resonance mechanism and become silent sand due to the damping action caused by the invasion of finer particles such as dust and clay into surface holes of sand grains. Therefore, clearing away fine pollutants on the quartz grain surface is an effective way to make silent sand emit audible sound.展开更多
Booming sand is regarded as a rare and interesting natural phenomenon. Scientists have put forward a variety of inferences and hypotheses on the sound-producing mechanism of booming sand. In recent several decades, sc...Booming sand is regarded as a rare and interesting natural phenomenon. Scientists have put forward a variety of inferences and hypotheses on the sound-producing mechanism of booming sand. In recent several decades, scientists have conducted quite a lot of research work on booming sand but little progress has been made in the acoustic mechanism of booming sand due to its complexity. So far, there still exist some divergences of views concerning the influences of surface texture of quartz grain on the sonorous property of booming sand. In this research we have made a systematic analysis on the influence展开更多
基金supported by the National Key R&D Program(2016YFC1303403)the Natural and Scientific Foundation of China(81572981,81201789,81672397,81400057)the National High-tech R&D program(2014AA020704)
文摘In 2013,cancer immunotherapy led the annual breakthroughs in Science.In fact,immunotherapy is one of the hotspots in cancer therapy,and can date back to the Coley vaccine in 1891.Advances in biotechnology and bio-engineering,especially research and development（R＆D）in the fields of therapeutic antibodies,checkpoint inhibitors,and engineered T cells,helped overcome the problems in tumor therapies,leading to increasing research focus on cancer immunotherapy.
文摘某客车70 km/h出现轰鸣噪声,严重影响乘坐舒适性。通过声振测试和声学仿真方法对轰鸣原因进行了研究,确定了轰鸣噪声是传动轴激励频率与车内声腔模态频率耦合引起。通过优化传动轴的剩余不平衡量,降低传动轴激励,消弱车内声振耦合作用。试验结果表明,车内轰鸣噪声得到明显改善,A计权声压级降低了1.45 d B(A),C计权声压级降低了6.77 d B(C)。
基金Supported by the National Natural Science Foundation of China (Grant Nos. 49401001 and 40501066)the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KZCX3-SW-341)
文摘The sound-producing mechanism of booming sand has long been a pending problem in the blown sand physics. Based on the earlier researches, the authors collected some silent sand samples from Teng- ger Desert, Australian Desert, Kuwait Desert, beaches of Hainan Island and Japanese coast as well as the soundless booming sand samples from the Mingsha Mountain in Dunhuang to make washing ex- periments. In the meantime the chemical corrosion experiment of glass micro-spheres, surface coating experiment and SEM examination were also conducted. The experimental results show that the sound production of booming sand seems to have nothing to do with the presence of SiO2 gel on the surface of sand grains and unrelated to the surface chemical composition of sand grains but is related to the resonance cavities formed by porous (pit-like) physical structure resulting from a number of factors such as wind erosion, water erosion, chemical corrosion and SiO2 gel deposition, etc. Its resonance mechanism is similar to that of Hemholz resonance cavity. Under the action of external forces, nu- merous spherical and sand grains with smooth surface and porous surface are set in motion and rub with each other to produce extremely weak vibration sound and then become audible sound by human ears through the magnification of surface cavity resonance. However the booming sands may lose their resonance mechanism and become silent sand due to the damping action caused by the invasion of finer particles such as dust and clay into surface holes of sand grains. Therefore, clearing away fine pollutants on the quartz grain surface is an effective way to make silent sand emit audible sound.
基金Project supported by the National Natural Science Foundation of China.
文摘Booming sand is regarded as a rare and interesting natural phenomenon. Scientists have put forward a variety of inferences and hypotheses on the sound-producing mechanism of booming sand. In recent several decades, scientists have conducted quite a lot of research work on booming sand but little progress has been made in the acoustic mechanism of booming sand due to its complexity. So far, there still exist some divergences of views concerning the influences of surface texture of quartz grain on the sonorous property of booming sand. In this research we have made a systematic analysis on the influence
