在大批生产青霉素 G 钾盐的过程中,提取及结晶的废液和母液中丢失了大量的青霉素。从发酵液中提取青霉素的总收率约75～80%。考虑到生产青霉素的费用昂贵,人们认为从上述废液中回收青霉素的可能性是值得研究的。人们已认识到,为了从青...在大批生产青霉素 G 钾盐的过程中,提取及结晶的废液和母液中丢失了大量的青霉素。从发酵液中提取青霉素的总收率约75～80%。考虑到生产青霉素的费用昂贵,人们认为从上述废液中回收青霉素的可能性是值得研究的。人们已认识到,为了从青霉素的水溶液中回收青霉素,特别是当青霉素在水相中浓度低的时候,离子交换是一种合适的方法。Samsonov 及其同事已在这个领域中做了大量的工作。在硫酸。展开更多
In the present paper, we discuss the solution of Euler-Darboux equation in terms of Dirichlet averages of boundary conditions on H?lder space and weighted H?lder spaces of continuous functions using Riemann-Liouville ...In the present paper, we discuss the solution of Euler-Darboux equation in terms of Dirichlet averages of boundary conditions on H?lder space and weighted H?lder spaces of continuous functions using Riemann-Liouville fractional integral operators. Moreover, the results are interpreted in alternative form.展开更多
Bearing as an important machine element is widely used for industrial and automotive applications.At certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,producti...Bearing as an important machine element is widely used for industrial and automotive applications.At certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,productivity and passenger comfort in case of vehicle applications.Dissipative elastic metamaterials have caught considerable attention of scientific community due to their effective medium properties and peculiar dynamic characteristics including frequency bandgaps that can be effectively applied to attenuate and control undesirable vibration and noises.Although a substantial amount of theoretical work for effective medium characteristics and dynamic properties of acoustic/elastic metamaterials has been reported,the practical design and application of these composite structures for real-life engineering problems still remain unexplored.The present study intends to investigate a potential application of dissipative elastic metamaterials in controlling the bearing-generated vibration and noises over an ultrawide frequency range.The study is based on a simple analytical model together with rigorous finite element numerical simulations.It has been established that the dissipative characteristic of resonant system caused by larger material mismatch broadens the local resonance bandgaps beyond the bounding resonance frequency at the cost of wave transmission.In order to achieve broadband vibration and noise control,multi-resonant composite structures are embedded inside the bearing housing in five different layers.The reported results revealed the presence of broadband wave attenuation zone distributed from 3 to 52 kHz with consideration of material damping.The bearing-generated vibration and noises lying inside the wave attenuation zone will be mitigated.This feasibility study provides a new concept for the design and application of acoustic/elastic metamaterials in the bearing industry to improve machine service life and to enhance productivity and passenger comfort.展开更多
文摘在大批生产青霉素 G 钾盐的过程中,提取及结晶的废液和母液中丢失了大量的青霉素。从发酵液中提取青霉素的总收率约75～80%。考虑到生产青霉素的费用昂贵,人们认为从上述废液中回收青霉素的可能性是值得研究的。人们已认识到,为了从青霉素的水溶液中回收青霉素,特别是当青霉素在水相中浓度低的时候,离子交换是一种合适的方法。Samsonov 及其同事已在这个领域中做了大量的工作。在硫酸。
文摘In the present paper, we discuss the solution of Euler-Darboux equation in terms of Dirichlet averages of boundary conditions on H?lder space and weighted H?lder spaces of continuous functions using Riemann-Liouville fractional integral operators. Moreover, the results are interpreted in alternative form.
基金The work described in this paper was supported by General Research Grants from the Research Grants Council of the Hong Kong Special Administrative Region(Project No.CityU 11216318)City University of Hong Kong(Project No.9680213)。
文摘Bearing as an important machine element is widely used for industrial and automotive applications.At certain operational speed,bearings induce disturbing vibrations and noises that affect machine service life,productivity and passenger comfort in case of vehicle applications.Dissipative elastic metamaterials have caught considerable attention of scientific community due to their effective medium properties and peculiar dynamic characteristics including frequency bandgaps that can be effectively applied to attenuate and control undesirable vibration and noises.Although a substantial amount of theoretical work for effective medium characteristics and dynamic properties of acoustic/elastic metamaterials has been reported,the practical design and application of these composite structures for real-life engineering problems still remain unexplored.The present study intends to investigate a potential application of dissipative elastic metamaterials in controlling the bearing-generated vibration and noises over an ultrawide frequency range.The study is based on a simple analytical model together with rigorous finite element numerical simulations.It has been established that the dissipative characteristic of resonant system caused by larger material mismatch broadens the local resonance bandgaps beyond the bounding resonance frequency at the cost of wave transmission.In order to achieve broadband vibration and noise control,multi-resonant composite structures are embedded inside the bearing housing in five different layers.The reported results revealed the presence of broadband wave attenuation zone distributed from 3 to 52 kHz with consideration of material damping.The bearing-generated vibration and noises lying inside the wave attenuation zone will be mitigated.This feasibility study provides a new concept for the design and application of acoustic/elastic metamaterials in the bearing industry to improve machine service life and to enhance productivity and passenger comfort.
