In certain exceptional cases,capillary samples must be used to measure X-ray absorption spectra(XAS).However,the inho-mogeneous thickness of capillary samples causes XAS distortion.This study discusses the distortion ...In certain exceptional cases,capillary samples must be used to measure X-ray absorption spectra(XAS).However,the inho-mogeneous thickness of capillary samples causes XAS distortion.This study discusses the distortion and correction of the XAS curve caused by the inhomogeneous thickness of capillary samples.The relationship between the distorted XAS curveμ′d_(eq)(measured values)and the real absorption coefficientμ_(s)d_(eq)(true values)of the sample was established.The distortion was slight and negligible when the vertical size(2h)of the X-ray beam spot was smaller than 60%of the capillary tube’s inner diameter(2R_(in)).When h/R_(in)>1,X-ray leakage is inevitable and should be avoided during measurement.Partial X-ray leakage caused by an X-ray beam spot size larger than the inner diameter of the capillary tube leads to serious compressed distortion of the XAS curve.When h/R_(in)<1,the distorted XAS data were well corrected.Possible errors and their influence on the corrected XAS are also discussed.Simulations and corrections for distortions verify the feasibility and effectiveness of the corrected method.展开更多
The JPEG2000 image compression standard is the powerful encoder which can provide phenomenal rate-control performance.The post-compression rate-distortion(PCRD)algorithm in JPEG2000 is not efficient.It requires encodi...The JPEG2000 image compression standard is the powerful encoder which can provide phenomenal rate-control performance.The post-compression rate-distortion(PCRD)algorithm in JPEG2000 is not efficient.It requires encoding all coding passes even though a large contribution of them will not be contained in the final code-stream.Tier-1 encoding in the JPEG2000 standard takes a significant amount of memory and coding time.In this work,a low-complexity rate distortion method for JPEG2000 is proposed.It is relied on a reverse order for the resolution levels and the coding passes.The proposed algorithm encodes only the coding passes contained in the final code-stream and it does not need any post compression rate control part.The computational complexity of proposed algorithm is negligible,making it suitable to compression and attaining a significant performance.Simulations results show that the proposed algorithm obtained the PSNR values are comparable with the optimal PCRD.展开更多
基金the National Key R&D Program of China(Nos.2022YFA1603802 and 2017YFA0403000)1W2B and 4B9A at the Beijing Synchrotron Radiation Facility.
文摘In certain exceptional cases,capillary samples must be used to measure X-ray absorption spectra(XAS).However,the inho-mogeneous thickness of capillary samples causes XAS distortion.This study discusses the distortion and correction of the XAS curve caused by the inhomogeneous thickness of capillary samples.The relationship between the distorted XAS curveμ′d_(eq)(measured values)and the real absorption coefficientμ_(s)d_(eq)(true values)of the sample was established.The distortion was slight and negligible when the vertical size(2h)of the X-ray beam spot was smaller than 60%of the capillary tube’s inner diameter(2R_(in)).When h/R_(in)>1,X-ray leakage is inevitable and should be avoided during measurement.Partial X-ray leakage caused by an X-ray beam spot size larger than the inner diameter of the capillary tube leads to serious compressed distortion of the XAS curve.When h/R_(in)<1,the distorted XAS data were well corrected.Possible errors and their influence on the corrected XAS are also discussed.Simulations and corrections for distortions verify the feasibility and effectiveness of the corrected method.
文摘The JPEG2000 image compression standard is the powerful encoder which can provide phenomenal rate-control performance.The post-compression rate-distortion(PCRD)algorithm in JPEG2000 is not efficient.It requires encoding all coding passes even though a large contribution of them will not be contained in the final code-stream.Tier-1 encoding in the JPEG2000 standard takes a significant amount of memory and coding time.In this work,a low-complexity rate distortion method for JPEG2000 is proposed.It is relied on a reverse order for the resolution levels and the coding passes.The proposed algorithm encodes only the coding passes contained in the final code-stream and it does not need any post compression rate control part.The computational complexity of proposed algorithm is negligible,making it suitable to compression and attaining a significant performance.Simulations results show that the proposed algorithm obtained the PSNR values are comparable with the optimal PCRD.
