Compared with wired communication,the wireless communication link is more vulnerable to be attacked or eavesdropped because of its broadcast nature.To prevent eavesdropping,many researches on transmission techniques o...Compared with wired communication,the wireless communication link is more vulnerable to be attacked or eavesdropped because of its broadcast nature.To prevent eavesdropping,many researches on transmission techniques or cryptographic methods are carried out.This paper proposes a new index parameter named as eavesdropping area,to evaluate the anti-eavesdropping performance of wireless system.Given the locations of legitimate transmitter and receiver,eavesdropping area index describes the total area of eavesdropping regions where messages can be wiretapped in the whole evaluating region.This paper gives detailed explanations about its concept and deduces mathematical formulas about performance curves based on region classification.Corresponding key system parameters are analyzed,including the characteristics of eavesdropping region,transmitted beam pattern,beam direction,receiver sensitivity,eavesdropping sensitivity,path loss exponent and so on.The proposed index can give an insight on the confirmation of high-risk eavesdropping region and formulating optimal transmitting scheme for the confidential communications to decrease the eavesdropping probability.展开更多
The clinical presentations of gestational choriocarcinoma vary markedly, and a misdiagnosis could be made in atypical patients if simply relying on clinical features. Laparoscopic resection of uterine mass lesion is r...The clinical presentations of gestational choriocarcinoma vary markedly, and a misdiagnosis could be made in atypical patients if simply relying on clinical features. Laparoscopic resection of uterine mass lesion is rarely used in gestational choriocarcinoma diagnosis because of the fear of heavy blood loss and distant metastasis. Five patients who were preoperatively diagnosed as having cornual pregnancy underwent laparoscopic resection of mass lesion and then proved to have gestational choriocarcinoma based on pathological examinations. Chemotherapy was started within two days after surgery, and the rate of complete remission was 100%. The mean follow-up time was 29.8±19.1 months, and no patient showed signs of relapse. Laparoscopic resection of uterine mass followed by timely postoperative chemotherapy may be an effective and safe way to obtain pathologic results in patients with suspected gestational choriocarcinoma.展开更多
This paper aims to develop a modified animal glue sand binder for foundry casting with improved water resistance and bonding strength.An efficient method is reported by using sodium hydroxide as the catalyst to improv...This paper aims to develop a modified animal glue sand binder for foundry casting with improved water resistance and bonding strength.An efficient method is reported by using sodium hydroxide as the catalyst to improve the operability of animal glue binder and allyl glycidyl ether as the modifier to improve the water resistance and bonding strength.Sand specimens prepared using allyl glycidyl ether-modified animal glue binder were cured by compressed air at room temperature.The proposed method saves energy and is environmentally friendly and inexpensive.Compared with unmodified animal glue binder,standard dog bone sand specimens with allyl glycidyl ether-modified animal glue binder had higher tensile strength of 2.58 MPa,flowability of 1.95 g,better water resistance(a lower decrease in tensile strength at 25°C and relative humidity of 60%),and good collapsibility.This allyl glycidyl ether-modified animal glue binder is suitable for practical application in the foundry industry.展开更多
Raman fiber lasers,known for their capacity to provide both high-power and precise wavelength emissions,are gaining attraction across a spectrum of applications,including fiber optic communications,sensing,spectroscop...Raman fiber lasers,known for their capacity to provide both high-power and precise wavelength emissions,are gaining attraction across a spectrum of applications,including fiber optic communications,sensing,spectroscopy and imaging.However,the scalability of Raman laser power is impeded by the constraints of pump brightness and the deleterious effects of second-order Raman scattering.In this research,we have undertaken a comprehensive experimental and simulation-based investigation into the impact of pump brightness on the output characteristics within an amplifier framework.Our innovative approach integrates high-brightness pumping with multi-mode graded-index fibers.Notably,we have pioneered the introduction of multi-wavelength seed light to facilitate four-wave mixing,thereby effectively mitigating higher-order Raman scattering.This novel strategy has culminated in the achievement of a 4 kW Raman laser output in an all-fiber configuration,representing the highest output power reported so far.展开更多
Raman imaging yields high specificity and sensitivity when compared to other imaging modalities, mainly due to its fingerprint signature. However, intrinsic Raman signals are weak, thus limiting medical applications o...Raman imaging yields high specificity and sensitivity when compared to other imaging modalities, mainly due to its fingerprint signature. However, intrinsic Raman signals are weak, thus limiting medical applications of Raman imaging. By adsorbing Raman molecules onto specific nanostructures such as noble metals, Raman signals can be significantly enhanced, termed surfaceenhanced Raman scattering(SERS). Recent years have witnessed great interest in the development of SERS nanoprobes for Raman imaging. Rationally designed SERS nanoprobes have greatly enhanced Raman signals by several orders of magnitude, thus showing great potential for biomedical applications.In this review we elaborate on recent progress in design strategies with emphasis on material properties,modifying factors, and structural parameters.展开更多
The superfluorescent fiber source(SFS)with tunable optical spectrum has shown great application potential in the sensing,imaging,and spectral combination.Here,we demonstrate for the first time a 2-kW-level wavelength ...The superfluorescent fiber source(SFS)with tunable optical spectrum has shown great application potential in the sensing,imaging,and spectral combination.Here,we demonstrate for the first time a 2-kW-level wavelength and linewidth tunable SFS.Based on a flexible filtered SFS seed and three stages of fiber amplifiers,the output power can be scaled from the milliwatt level to about 2 kW,with a wavelength tuning range of 1068–1092 nm and a linewidth tuning range of 2.5–9.7 nm.Moreover,a numerical simulation is conducted based on the generalized nonlinear Schr?dinger equation,and the results reveal that the wavelength tuning range is limited by the decrease of seed power and the growth of amplified spontaneous emission,whereas the linewidth tuning range is determined by the gain competition and nonlinear Kerr effects.The developed wavelength and linewidth tunable SFS may be applied to scientific research and industrial processing.展开更多
The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and industry.The challenge for performance scalability of high-power SW lase...The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and industry.The challenge for performance scalability of high-power SW lasers based on rare-earth-doped fiber primarily lies in the physical limitations,including reabsorption,amplified spontaneous emission and parasitic laser oscillation.Here,we demonstrate an all-fiberized,purely passive SW(1018 nm)randomdistributed-feedback Raman fiber laser(RRFL)to validate the capability of achieving high-power output at SWs based on multimode laser diodes(LDs)direct pumping.Directly pumped by multimode LDs,the high-brightness RRFL delivers over 656 W,with an electro-optical efficiency of 20%relative to the power.The slope efficiency is 94%.The beam quality M2factor is 2.9(which is~20 times that of the pump)at the maximum output signal power,achieving the highest brightness enhancement of 14.9 in RRFLs.To the best of our knowledge,this achievement also represents the highest power record of RRFLs utilizing multimode diodes for direct pumping.This work may not only provide a new insight into the realization of high-power,high-brightness RRFLs but also is a promising contender in the power scaling of SWs below 1μm.展开更多
Fiber Bragg grating-based Raman oscillators are capable of achieving targeted frequency conversion and brightness enhancement through the provision of gain via stimulated Raman scattering across a broad gain spectrum....Fiber Bragg grating-based Raman oscillators are capable of achieving targeted frequency conversion and brightness enhancement through the provision of gain via stimulated Raman scattering across a broad gain spectrum. This capability renders them an exemplary solution for the acquisition of high-brightness, specialized-wavelength lasers. Nonetheless,the output power of all-fiber Raman oscillators is typically limited to several hundred watts, primarily due to limitations in injectable pump power and the influence of higher-order Raman effects, which is inadequate for certain application demands. In this study, we introduce an innovative approach by employing a graded-index fiber with a core diameter of up to 150 μm as the Raman gain medium. This strategy not only enhances the injectable pump power but also mitigates higher-order Raman effects. Consequently, we have successfully attained an output power of 1780 W for the all-fiber Raman laser at 1130 nm, representing the highest output power in Raman fiber oscillators with any configuration reported to date.展开更多
文摘Compared with wired communication,the wireless communication link is more vulnerable to be attacked or eavesdropped because of its broadcast nature.To prevent eavesdropping,many researches on transmission techniques or cryptographic methods are carried out.This paper proposes a new index parameter named as eavesdropping area,to evaluate the anti-eavesdropping performance of wireless system.Given the locations of legitimate transmitter and receiver,eavesdropping area index describes the total area of eavesdropping regions where messages can be wiretapped in the whole evaluating region.This paper gives detailed explanations about its concept and deduces mathematical formulas about performance curves based on region classification.Corresponding key system parameters are analyzed,including the characteristics of eavesdropping region,transmitted beam pattern,beam direction,receiver sensitivity,eavesdropping sensitivity,path loss exponent and so on.The proposed index can give an insight on the confirmation of high-risk eavesdropping region and formulating optimal transmitting scheme for the confidential communications to decrease the eavesdropping probability.
基金supported by a grant of Beijing Municipal Science&Technology Commission,China(Grant No.Z131107002213173)
文摘The clinical presentations of gestational choriocarcinoma vary markedly, and a misdiagnosis could be made in atypical patients if simply relying on clinical features. Laparoscopic resection of uterine mass lesion is rarely used in gestational choriocarcinoma diagnosis because of the fear of heavy blood loss and distant metastasis. Five patients who were preoperatively diagnosed as having cornual pregnancy underwent laparoscopic resection of mass lesion and then proved to have gestational choriocarcinoma based on pathological examinations. Chemotherapy was started within two days after surgery, and the rate of complete remission was 100%. The mean follow-up time was 29.8±19.1 months, and no patient showed signs of relapse. Laparoscopic resection of uterine mass followed by timely postoperative chemotherapy may be an effective and safe way to obtain pathologic results in patients with suspected gestational choriocarcinoma.
基金This work was supported by Chongqing Science and Technology Commission(cstc2017shmsA90014)Fundamental Research Funds for the Central Universities(XDJK2019AA003)We thank Kathryn Sole,PhD,from Liwen Bianji,Edanz Group China(www.liwenbianji.cn/ac),for editing the English text of a draft of this manuscript.
文摘This paper aims to develop a modified animal glue sand binder for foundry casting with improved water resistance and bonding strength.An efficient method is reported by using sodium hydroxide as the catalyst to improve the operability of animal glue binder and allyl glycidyl ether as the modifier to improve the water resistance and bonding strength.Sand specimens prepared using allyl glycidyl ether-modified animal glue binder were cured by compressed air at room temperature.The proposed method saves energy and is environmentally friendly and inexpensive.Compared with unmodified animal glue binder,standard dog bone sand specimens with allyl glycidyl ether-modified animal glue binder had higher tensile strength of 2.58 MPa,flowability of 1.95 g,better water resistance(a lower decrease in tensile strength at 25°C and relative humidity of 60%),and good collapsibility.This allyl glycidyl ether-modified animal glue binder is suitable for practical application in the foundry industry.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174445 and 62061136013)。
文摘Raman fiber lasers,known for their capacity to provide both high-power and precise wavelength emissions,are gaining attraction across a spectrum of applications,including fiber optic communications,sensing,spectroscopy and imaging.However,the scalability of Raman laser power is impeded by the constraints of pump brightness and the deleterious effects of second-order Raman scattering.In this research,we have undertaken a comprehensive experimental and simulation-based investigation into the impact of pump brightness on the output characteristics within an amplifier framework.Our innovative approach integrates high-brightness pumping with multi-mode graded-index fibers.Notably,we have pioneered the introduction of multi-wavelength seed light to facilitate four-wave mixing,thereby effectively mitigating higher-order Raman scattering.This novel strategy has culminated in the achievement of a 4 kW Raman laser output in an all-fiber configuration,representing the highest output power reported so far.
基金the National Natural Science Foundation of China(Nos.81471779 and 31671003)Thousand Young Talents Program,the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(No.TP2014028)for their financial support
文摘Raman imaging yields high specificity and sensitivity when compared to other imaging modalities, mainly due to its fingerprint signature. However, intrinsic Raman signals are weak, thus limiting medical applications of Raman imaging. By adsorbing Raman molecules onto specific nanostructures such as noble metals, Raman signals can be significantly enhanced, termed surfaceenhanced Raman scattering(SERS). Recent years have witnessed great interest in the development of SERS nanoprobes for Raman imaging. Rationally designed SERS nanoprobes have greatly enhanced Raman signals by several orders of magnitude, thus showing great potential for biomedical applications.In this review we elaborate on recent progress in design strategies with emphasis on material properties,modifying factors, and structural parameters.
基金supported by the National Natural Science Foundation of China(Nos.62061136013 and 61905284)the Hunan Provincial Innovation Construct Project(No.2019RS3018)the Director Fund of the State Key Laboratory of Pulsed Power Laser Technology(No.SKL2019ZR01)。
文摘The superfluorescent fiber source(SFS)with tunable optical spectrum has shown great application potential in the sensing,imaging,and spectral combination.Here,we demonstrate for the first time a 2-kW-level wavelength and linewidth tunable SFS.Based on a flexible filtered SFS seed and three stages of fiber amplifiers,the output power can be scaled from the milliwatt level to about 2 kW,with a wavelength tuning range of 1068–1092 nm and a linewidth tuning range of 2.5–9.7 nm.Moreover,a numerical simulation is conducted based on the generalized nonlinear Schr?dinger equation,and the results reveal that the wavelength tuning range is limited by the decrease of seed power and the growth of amplified spontaneous emission,whereas the linewidth tuning range is determined by the gain competition and nonlinear Kerr effects.The developed wavelength and linewidth tunable SFS may be applied to scientific research and industrial processing.
基金supported by the National Natural Science Foundation of China(Nos.62061136013 and 12174445)。
文摘The power scaling on short wavelength(SW)fiber lasers operating around 1μm are in significant demand for applications in energy,environment and industry.The challenge for performance scalability of high-power SW lasers based on rare-earth-doped fiber primarily lies in the physical limitations,including reabsorption,amplified spontaneous emission and parasitic laser oscillation.Here,we demonstrate an all-fiberized,purely passive SW(1018 nm)randomdistributed-feedback Raman fiber laser(RRFL)to validate the capability of achieving high-power output at SWs based on multimode laser diodes(LDs)direct pumping.Directly pumped by multimode LDs,the high-brightness RRFL delivers over 656 W,with an electro-optical efficiency of 20%relative to the power.The slope efficiency is 94%.The beam quality M2factor is 2.9(which is~20 times that of the pump)at the maximum output signal power,achieving the highest brightness enhancement of 14.9 in RRFLs.To the best of our knowledge,this achievement also represents the highest power record of RRFLs utilizing multimode diodes for direct pumping.This work may not only provide a new insight into the realization of high-power,high-brightness RRFLs but also is a promising contender in the power scaling of SWs below 1μm.
基金supported by the National Natural Science Foundation of China(Nos.12174445 and 62061136013)
文摘Fiber Bragg grating-based Raman oscillators are capable of achieving targeted frequency conversion and brightness enhancement through the provision of gain via stimulated Raman scattering across a broad gain spectrum. This capability renders them an exemplary solution for the acquisition of high-brightness, specialized-wavelength lasers. Nonetheless,the output power of all-fiber Raman oscillators is typically limited to several hundred watts, primarily due to limitations in injectable pump power and the influence of higher-order Raman effects, which is inadequate for certain application demands. In this study, we introduce an innovative approach by employing a graded-index fiber with a core diameter of up to 150 μm as the Raman gain medium. This strategy not only enhances the injectable pump power but also mitigates higher-order Raman effects. Consequently, we have successfully attained an output power of 1780 W for the all-fiber Raman laser at 1130 nm, representing the highest output power in Raman fiber oscillators with any configuration reported to date.
