To make speech watermarking achieve both copyright protection and integrity verification, a novel multipurpose speech watermarking algorithm based on the multistage vector quantization （MSVQ） of linear prediction co...To make speech watermarking achieve both copyright protection and integrity verification, a novel multipurpose speech watermarking algorithm based on the multistage vector quantization （MSVQ） of linear prediction coefficients （LPCs） is presented in this article. The property of natural speech that the vector quantization （VQ） indices of the LPCs amongst neighboring frames tend to be very similar is utilized to embed the robust watermark in the indices of the first-stage VQ（VQ1）. Then, the semi-fragile watermark is embedded in the indices of the second-stage VQ（VQ2） with index constrained VQ encoding scheme. Both the robust watermark and the semi-fragile watermark can be extracted without host speech. Simulation results verify the effectiveness of the proposed algorithm in terms of robustness and semi-fragility.展开更多
Information hiding techniques adopted in secret communication should meet the requirements of high hiding capacity,real-time and high robustness.For the purpose of real-time speech secure communication,an information ...Information hiding techniques adopted in secret communication should meet the requirements of high hiding capacity,real-time and high robustness.For the purpose of real-time speech secure communication,an information hiding algorithm based on the analysis-by-synthesis（ABS） speech coding scheme is presented in this article.This algorithm substitutes secret speech data bits for linear predictive coefficients（LPCs） in linear predictive coding（LPC）.Statistics show that the change of voiced signal track is slow and the codebook for LPCs vector is large in ABS coding scheme.Therefore,a new concept,filter similarity,is proposed to determine the LPC parameters for substituting with secret speech information,and to generate multi-codebook for saving storage space to store secret speech information.To achieve the best effects of information hiding,a dynamic threshold is built to make an optimal trade-off among hiding-capacity,security,robustness,transparence and real time.Experiments show that the proposed approach meets the requirements of information hiding and secret communication speech quality.The test results indicate that this approach reaches high hiding capacity with an excellent speech quality and complicating speakers＇ recognition.展开更多
Six-junction vertically-stacked Ga As laser power converters（LPCs） with n^＋-Ga As/p^＋-Al0.37 Ga0.63 As tunnel junctions have been designed and grown by metal-organic chemical vapor deposition for converting the po...Six-junction vertically-stacked Ga As laser power converters（LPCs） with n^＋-Ga As/p^＋-Al0.37 Ga0.63 As tunnel junctions have been designed and grown by metal-organic chemical vapor deposition for converting the power of 808 nm lasers. The LPC chips are characterized by measuring current–voltage（I–V） characteristics under 808 nm laser illumination, and a maximum conversion efficiency ηc of 53.1% is obtained for LPCs with an aperture diameter of 2 mm at an input laser power of 0.5 W. In addition, the characteristics of the LPCs are analyzed by a standard equivalent-circuit model, and the reverse saturation current, ideality factor, series resistance and shunt resistance are extracted by fitting of the I–V curves.展开更多
Four-junction A1GaAs/GaAs laser power converters （LPCs） with n＋-GaAs/p＋-A10.37Ga0.63As hetero- structure tunnel junctions （TJs） have been designed and grown by metal-organic chemical vapor deposition （MOCVD） f...Four-junction A1GaAs/GaAs laser power converters （LPCs） with n＋-GaAs/p＋-A10.37Ga0.63As hetero- structure tunnel junctions （TJs） have been designed and grown by metal-organic chemical vapor deposition （MOCVD） for converting the power of 808 nm lasers. A maximum conversion efficiency ηc of 56.9% ＋ 4% is obtained for cells with an aperture of 3.14 mm2 at an input laser power of 0.2 W, while dropping to 43.3% at 1.5 W. Measured current-voltage （I-V） characteristics indicate that the performance of the LPC can be further improved by increasing the tunneling current density of TJs and optimizing the thicknesses of sub-cells to achieve current matching in LPC.展开更多
The liver is well known for its ability to regenerate in response to injury. After partial hepatectomy and some chemicals induced acute liver injury, existing hepatocytes can expand to repair the liver function. While...The liver is well known for its ability to regenerate in response to injury. After partial hepatectomy and some chemicals induced acute liver injury, existing hepatocytes can expand to repair the liver function. While adult liver stem/progenitor cells(LPCs) are evoked and differentiate into functional hepatocytes and cholangiocytes to compensate the damaged liver once hepatocyte proliferation is severely impaired. A number of evidences suggest that adjacent hepatic stellate cells(HSCs) or invading leukocytes may be involved in LPCs directed regeneration through governning two major events including fibrogenic and inflammatory responses respectively or simultaneously. As such, a microenvironment(or "niche") composed of different cell sources or factors presents diversity, which eventually mediates LPCs response to biliary or hepatocellular regeneration. This mini review aims at summarizing the latest development on the roles of HSCs, macrophages and lymphocytes as well as corresponding signaling pathways in liver progenitor cells mediated biliary and hepatocellular regeneration, and discussing therapeutic potential of liver progenitor cells in hepatic diseases.展开更多
The gradient doping regions were employed in the emitter layer and the base layer of GaAs based laser power converters(LPCs).Silvaco TCAD was used to numerically simulate the linear gradient doping and exponential gra...The gradient doping regions were employed in the emitter layer and the base layer of GaAs based laser power converters(LPCs).Silvaco TCAD was used to numerically simulate the linear gradient doping and exponential gradient doping structure,and analyze the transport process of photogenerated carriers.Energy band adjustment via gradient doping improved the separation and transport efficiency of photogenerated carriers and reduced the total recombination rate of GaAs LPCs.Compared with traditional structure of LPCs,the photoelectric conversion efficiency of LPCs with linear and exponential gradient doping structure were improved from 52.7%to 57.2%and 57.7%,respectively,under 808 nm laser light at the power density of 1 W/cm^(2).展开更多
文摘To make speech watermarking achieve both copyright protection and integrity verification, a novel multipurpose speech watermarking algorithm based on the multistage vector quantization （MSVQ） of linear prediction coefficients （LPCs） is presented in this article. The property of natural speech that the vector quantization （VQ） indices of the LPCs amongst neighboring frames tend to be very similar is utilized to embed the robust watermark in the indices of the first-stage VQ（VQ1）. Then, the semi-fragile watermark is embedded in the indices of the second-stage VQ（VQ2） with index constrained VQ encoding scheme. Both the robust watermark and the semi-fragile watermark can be extracted without host speech. Simulation results verify the effectiveness of the proposed algorithm in terms of robustness and semi-fragility.
基金supported by the National Natural Science Foundation of China (60776808)the National Natural Science Foundation of Tianjin (09JCYBJC00400)
文摘Information hiding techniques adopted in secret communication should meet the requirements of high hiding capacity,real-time and high robustness.For the purpose of real-time speech secure communication,an information hiding algorithm based on the analysis-by-synthesis（ABS） speech coding scheme is presented in this article.This algorithm substitutes secret speech data bits for linear predictive coefficients（LPCs） in linear predictive coding（LPC）.Statistics show that the change of voiced signal track is slow and the codebook for LPCs vector is large in ABS coding scheme.Therefore,a new concept,filter similarity,is proposed to determine the LPC parameters for substituting with secret speech information,and to generate multi-codebook for saving storage space to store secret speech information.To achieve the best effects of information hiding,a dynamic threshold is built to make an optimal trade-off among hiding-capacity,security,robustness,transparence and real time.Experiments show that the proposed approach meets the requirements of information hiding and secret communication speech quality.The test results indicate that this approach reaches high hiding capacity with an excellent speech quality and complicating speakers＇ recognition.
基金supported by the National Natural Science Foundation of China(No.61604171)the Jiangsu Province Science Foundation for Youths(No.BK20170431)Zhongtian Technology Group Co.Ltd
文摘Six-junction vertically-stacked Ga As laser power converters（LPCs） with n^＋-Ga As/p^＋-Al0.37 Ga0.63 As tunnel junctions have been designed and grown by metal-organic chemical vapor deposition for converting the power of 808 nm lasers. The LPC chips are characterized by measuring current–voltage（I–V） characteristics under 808 nm laser illumination, and a maximum conversion efficiency ηc of 53.1% is obtained for LPCs with an aperture diameter of 2 mm at an input laser power of 0.5 W. In addition, the characteristics of the LPCs are analyzed by a standard equivalent-circuit model, and the reverse saturation current, ideality factor, series resistance and shunt resistance are extracted by fitting of the I–V curves.
基金Project financially supported by the National Natural Science Foundation of China(No.61376065)Zhongtian Technology Group Co.Ltd
文摘Four-junction A1GaAs/GaAs laser power converters （LPCs） with n＋-GaAs/p＋-A10.37Ga0.63As hetero- structure tunnel junctions （TJs） have been designed and grown by metal-organic chemical vapor deposition （MOCVD） for converting the power of 808 nm lasers. A maximum conversion efficiency ηc of 56.9% ＋ 4% is obtained for cells with an aperture of 3.14 mm2 at an input laser power of 0.2 W, while dropping to 43.3% at 1.5 W. Measured current-voltage （I-V） characteristics indicate that the performance of the LPC can be further improved by increasing the tunneling current density of TJs and optimizing the thicknesses of sub-cells to achieve current matching in LPC.
基金the Program of the State Key Laboratory for Oncogenes and Related Genes,Renji Hospital,Shanghai Jiao Tong University School of Medicine(No.90-13-02)
文摘The liver is well known for its ability to regenerate in response to injury. After partial hepatectomy and some chemicals induced acute liver injury, existing hepatocytes can expand to repair the liver function. While adult liver stem/progenitor cells(LPCs) are evoked and differentiate into functional hepatocytes and cholangiocytes to compensate the damaged liver once hepatocyte proliferation is severely impaired. A number of evidences suggest that adjacent hepatic stellate cells(HSCs) or invading leukocytes may be involved in LPCs directed regeneration through governning two major events including fibrogenic and inflammatory responses respectively or simultaneously. As such, a microenvironment(or "niche") composed of different cell sources or factors presents diversity, which eventually mediates LPCs response to biliary or hepatocellular regeneration. This mini review aims at summarizing the latest development on the roles of HSCs, macrophages and lymphocytes as well as corresponding signaling pathways in liver progenitor cells mediated biliary and hepatocellular regeneration, and discussing therapeutic potential of liver progenitor cells in hepatic diseases.
基金This work was supported by the National Key R&D Program of China(No.2018YFB1500500)also supported by Ally Fund of Chinese Academy of Sciences(No.Y072051002).
文摘The gradient doping regions were employed in the emitter layer and the base layer of GaAs based laser power converters(LPCs).Silvaco TCAD was used to numerically simulate the linear gradient doping and exponential gradient doping structure,and analyze the transport process of photogenerated carriers.Energy band adjustment via gradient doping improved the separation and transport efficiency of photogenerated carriers and reduced the total recombination rate of GaAs LPCs.Compared with traditional structure of LPCs,the photoelectric conversion efficiency of LPCs with linear and exponential gradient doping structure were improved from 52.7%to 57.2%and 57.7%,respectively,under 808 nm laser light at the power density of 1 W/cm^(2).
