A time-domain method, based on linear velocity potential theory, is presented to study the interaction between narrow-banded random waves and perforated structures. A simple relation is derived to estimate the jet len...A time-domain method, based on linear velocity potential theory, is presented to study the interaction between narrow-banded random waves and perforated structures. A simple relation is derived to estimate the jet length of flows through the perforated wall. The reflection coefficient of narrow banded random waves from perforated structures is calculated by assuming a Rayleigh distribution of the heights of incident random waves. For reflection of narrow-banded waves from a single-chamber perforated breakwater, a comparison of the predicted and measured reflection coefficients shows that the method presented in this paper can provide a prediction better than that of regular waves. Numerical results are also reported on the reflection of narrow-banded waves from multi-chamber perforated breakwaters.展开更多
1 Introduction Early attempts to create a sound absorber which would function without the involvement of any fibrous or porous damping material go far back to K. A. Veliszhanina, S. N. Rschevkin and others as was out...1 Introduction Early attempts to create a sound absorber which would function without the involvement of any fibrous or porous damping material go far back to K. A. Veliszhanina, S. N. Rschevkin and others as was outlined in Ref. [1]. 30 years ago, D. Y. MAA[2] was first in proposing a practicable design concept and calculation model for Micro-Perforated Absorber （MPA） prototypes which still forms the basis for various applications. During the past 12 years the Fraunhofer IBP developed a whole family of MPA products in close cooperation with 8 or more industrial partners operating in a variety of widely differing market segments. Meanwhile a large number of MPA modules and surface elements have evolved from MAA＇s creative pioneer work. More and more ambitious acousticians have, more recently, caught on this attractive idea of employing absorbers made of non-fibrous, non-abrasive materials with non-polluting, almost closed and optically attractive surfaces. MPA structures have played an important part in a long-standing and on-going effort at IBP to establish novel Alternative Fibreless Absorber （ALFA） tools for a better noise control and acoustic comfort.展开更多
Recently, individual reduced-symmetry metal nanostructures and their plasmonic properties have been studied extensively. However, little attention has been paid to the approach to fabricating ordered reduced-symmetry ...Recently, individual reduced-symmetry metal nanostructures and their plasmonic properties have been studied extensively. However, little attention has been paid to the approach to fabricating ordered reduced-symmetry metal nanostructure arrays. In this paper, a novel perforated silver nanocap array with high surface-enhanced Raman scattering （SERS） activity and fluorescence suppression is reported. The array is fabricated by electron beam evaporating Ag onto the perforated barrier layer side of a hard anodization （HA） anodic aluminum oxide （AAO） template. The morphology and optical property of the perforated silver nanocap array are characterized by an atomic force microscope （AFM）, a scanning electron microscope （SEM）, and absorption spectra. The results of SERS measurements reveal that the perforated silver nanocap array offers high SERS activity and fluorescence suppression compared with an imperforated silver nanocap array.展开更多
Objective. To explore an effective method of surgical management of craniopharyngioma. Subjects and methods. Fifty patients with craniopharyngioma had total andsubtotal tumor ectomy. There were 29 males and 21 females...Objective. To explore an effective method of surgical management of craniopharyngioma. Subjects and methods. Fifty patients with craniopharyngioma had total andsubtotal tumor ectomy. There were 29 males and 21 females, ranging in age from 15 to 56 years (mean 34.1 years). MR imaging showed that the tumors were locatedin the superior sellar region in 24 cases, in superior sella region and extended into the third ventricular floor in 19 cases, into parasella in 3 cases and down to intrasella in 4 cases. Complete cystic tumors were found in 5 cases, whilethe partial cystic tumor in 24 cases and complete solid tumors in 21 cases. Pterional approach was used in 48 patients and subfrontal approach in 2 patients. Great attention was paid to the preservation of the perforating arteries from thecarotid, posterior and anterior communicating and anterior choroidal arteries to the hypothalamic structures. The clinical outcome was evaluated according to the GOS scale.Results. Of the 50 patients surgically treated, 47 patients obtained total ectomy of the tumor and 3 patients with the secondary surgery had subtotal ectomy of the tumor. The pituitary stalk was preserved in 29(58%) patients, severed in 14 patients and unidentified in 7 patients. Forty-six patients regained a normal life; one patient needed assist in life. Of the 3 deaths, one patient died of diabetes insipidus, one of inhalation asphyxia, and another one of water and sodium disorders. Conclusion. Avoidance of the injury to the neural structures in the thirdventricular floor and preservation of the perforating arteries to hypothalamus are the key to achieve good surgical results in treating craniopharyngioma.展开更多
基金The project partially supported by the Hong Kong Research Grant Council (DAG03/04.EG39, DAG04/05.EG32)
文摘A time-domain method, based on linear velocity potential theory, is presented to study the interaction between narrow-banded random waves and perforated structures. A simple relation is derived to estimate the jet length of flows through the perforated wall. The reflection coefficient of narrow banded random waves from perforated structures is calculated by assuming a Rayleigh distribution of the heights of incident random waves. For reflection of narrow-banded waves from a single-chamber perforated breakwater, a comparison of the predicted and measured reflection coefficients shows that the method presented in this paper can provide a prediction better than that of regular waves. Numerical results are also reported on the reflection of narrow-banded waves from multi-chamber perforated breakwaters.
文摘1 Introduction Early attempts to create a sound absorber which would function without the involvement of any fibrous or porous damping material go far back to K. A. Veliszhanina, S. N. Rschevkin and others as was outlined in Ref. [1]. 30 years ago, D. Y. MAA[2] was first in proposing a practicable design concept and calculation model for Micro-Perforated Absorber （MPA） prototypes which still forms the basis for various applications. During the past 12 years the Fraunhofer IBP developed a whole family of MPA products in close cooperation with 8 or more industrial partners operating in a variety of widely differing market segments. Meanwhile a large number of MPA modules and surface elements have evolved from MAA＇s creative pioneer work. More and more ambitious acousticians have, more recently, caught on this attractive idea of employing absorbers made of non-fibrous, non-abrasive materials with non-polluting, almost closed and optically attractive surfaces. MPA structures have played an important part in a long-standing and on-going effort at IBP to establish novel Alternative Fibreless Absorber （ALFA） tools for a better noise control and acoustic comfort.
基金Project supported by the Industry Key Technologies R & D Project in Shaanxi Province of China (Grant No. 2012K07-19)
文摘Recently, individual reduced-symmetry metal nanostructures and their plasmonic properties have been studied extensively. However, little attention has been paid to the approach to fabricating ordered reduced-symmetry metal nanostructure arrays. In this paper, a novel perforated silver nanocap array with high surface-enhanced Raman scattering （SERS） activity and fluorescence suppression is reported. The array is fabricated by electron beam evaporating Ag onto the perforated barrier layer side of a hard anodization （HA） anodic aluminum oxide （AAO） template. The morphology and optical property of the perforated silver nanocap array are characterized by an atomic force microscope （AFM）, a scanning electron microscope （SEM）, and absorption spectra. The results of SERS measurements reveal that the perforated silver nanocap array offers high SERS activity and fluorescence suppression compared with an imperforated silver nanocap array.
文摘Objective. To explore an effective method of surgical management of craniopharyngioma. Subjects and methods. Fifty patients with craniopharyngioma had total andsubtotal tumor ectomy. There were 29 males and 21 females, ranging in age from 15 to 56 years (mean 34.1 years). MR imaging showed that the tumors were locatedin the superior sellar region in 24 cases, in superior sella region and extended into the third ventricular floor in 19 cases, into parasella in 3 cases and down to intrasella in 4 cases. Complete cystic tumors were found in 5 cases, whilethe partial cystic tumor in 24 cases and complete solid tumors in 21 cases. Pterional approach was used in 48 patients and subfrontal approach in 2 patients. Great attention was paid to the preservation of the perforating arteries from thecarotid, posterior and anterior communicating and anterior choroidal arteries to the hypothalamic structures. The clinical outcome was evaluated according to the GOS scale.Results. Of the 50 patients surgically treated, 47 patients obtained total ectomy of the tumor and 3 patients with the secondary surgery had subtotal ectomy of the tumor. The pituitary stalk was preserved in 29(58%) patients, severed in 14 patients and unidentified in 7 patients. Forty-six patients regained a normal life; one patient needed assist in life. Of the 3 deaths, one patient died of diabetes insipidus, one of inhalation asphyxia, and another one of water and sodium disorders. Conclusion. Avoidance of the injury to the neural structures in the thirdventricular floor and preservation of the perforating arteries to hypothalamus are the key to achieve good surgical results in treating craniopharyngioma.
