BACKGROUND Median arcuate ligament syndrome(MALS)is a rare disease caused by compression of the celiac trunk artery by the median arcuate ligament(MAL).It can cause symptoms of postprandial abdominal pain,weight loss,...BACKGROUND Median arcuate ligament syndrome(MALS)is a rare disease caused by compression of the celiac trunk artery by the median arcuate ligament(MAL).It can cause symptoms of postprandial abdominal pain,weight loss,and nausea and vomiting.CASE SUMMARY A 55-year-old woman was admitted due to abdominal pain,nausea and vomiting.On admission,the patient presented with epigastric pain that worsened after eating,without signs of peritoneal irritation.Computed tomography angiography of the upper abdomen showed compression of the proximal segment of the abdominal trunk,local luminal stenosis with angular“fishhook”changes,which changed significantly during forceful inspiration and expiration;gallbladder stones;and multiple cysts in the liver.Abdominal duplex ultrasonography showed that peak systolic velocity was 352 cm/s.After diagnosis of MALS was confirmed,an arch ligament release procedure was performed.MALS has no specific symptoms and can be misdiagnosed as other abdominal diseases.Awareness of MALS should be improved to avoid misdiagnosis.The commonly used treatment option is MAL release and resection of the peripheral ganglion of the celiac trunk artery.CONCLUSION The diagnosis and treatment of MALS must be individualized,and MAL release is effective and provides immediate symptomatic relief.展开更多
Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechani...Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechanical experiments,logging interpretation,and seismic data,a 3 D geological model and heterogeneous rock mechanics field of the reservoir were constructed.Finite element simulation techniques were then used for the detailed prediction of the 3 D stress field.The results indicated that the maximum horizontal stress orientation in the study area was generally NEE-SWW trending,with significant changes in the in situ stress orientation within and between fault blocks.Along surfaces and profiles,stress magnitudes were discrete and the in situ stress belonged to theⅠa-type.Observed inter-strata differences were characterized as five different types of in situ stress profile.Faults were the most important factor causing large distributional differences in the stress field of reservoirs within the complex fault blocks.The next important influence on the stress field was the reservoir’s rock mechanics parameters,which impacted on the magnitudes of in situ stress magnitudes.This technique provided a theoretical basis for more efficient exploration and development of low-permeability reservoirs within complex fault blocks.展开更多
The classification of low permeability-tight reservoirs is the premise of development. The deep reservoir of Shahejie 3 member contains rich low permeability-tight reserves, but the strong heterogeneity and complex mi...The classification of low permeability-tight reservoirs is the premise of development. The deep reservoir of Shahejie 3 member contains rich low permeability-tight reserves, but the strong heterogeneity and complex micro pore structure make the main controlling factors subjective and the classification boundaries unclear. Therefore, a new indicator considering the interaction between fluid and rock named Threshold Flow Zone Indicator(TFZI) is proposed, it can be used as the main sequence of correlation analysis to screen the main controlling factors, and the clustering algorithm is optimized combined with probability distribution to determine the classification boundaries. The sorting coefficient, main throat radius, movable fluid saturation and displacement pressure are screened as the representative parameters for the following four key aspects: rock composition, microstructure, flow capacity and the interaction between rock and fluid. Compared with the traditional probability distribution and clustering algorithm, the boundary of the optimized clustering algorithm proposed in this paper is more accurate.The classification results are consistent with sedimentary facies, oil levels and oil production intensity.This method provides an important basis for the development of low permeability-tight reservoirs.展开更多
Low temperature(77 K)photoluminescence measurements have been performed on different GaAs substrates to evaluate the GaAs crystal quality.Several defect-related luminescence peaks have been observed,including 1.452 eV...Low temperature(77 K)photoluminescence measurements have been performed on different GaAs substrates to evaluate the GaAs crystal quality.Several defect-related luminescence peaks have been observed,including 1.452 eV,1.476 eV,1.326 eV peaks deriving from 78 meV GaAs antisite defects,and 1.372 eV,1.289 eV peaks resulting from As vacancy related defects.Changes in photoluminescence emission intensity and emission energy as a function of temperature and excitation power lead to the identification of the defect states.The luminescence mechanisms of the defect states were studied by photoluminescence spectroscopy and the growth quality of GaAs crystal was evaluated.展开更多
Satellite Internet of Things(IoT)is a promising way to provide seamless coverage to a massive number of devices all over the world,especially in remote areas not covered by cellular networks,e.g.,forests,oceans,mounta...Satellite Internet of Things(IoT)is a promising way to provide seamless coverage to a massive number of devices all over the world,especially in remote areas not covered by cellular networks,e.g.,forests,oceans,mountains,and deserts.In general,satellite IoT networks take low Earth orbit(LEO)satellites as access points,which solves the problem of wide coverage,but leads to many challenging issues.We first give an overview of satellite IoT,with an emphasis on revealing the characteristics of IoT services.Then,the challenging issues of satellite IoT,i.e.,massive connectivity,wide coverage,high mobility,low power,and stringent delay,are analyzed in detail.Furthermore,the possible solutions to these challenges are provided.In particular,new massive access protocols and techniques are designed according to the characteristics and requirements of satellite IoT.Finally,we discuss several development trends of satellite IoT to stimulate and encourage further research in such a broad area.展开更多
文摘BACKGROUND Median arcuate ligament syndrome(MALS)is a rare disease caused by compression of the celiac trunk artery by the median arcuate ligament(MAL).It can cause symptoms of postprandial abdominal pain,weight loss,and nausea and vomiting.CASE SUMMARY A 55-year-old woman was admitted due to abdominal pain,nausea and vomiting.On admission,the patient presented with epigastric pain that worsened after eating,without signs of peritoneal irritation.Computed tomography angiography of the upper abdomen showed compression of the proximal segment of the abdominal trunk,local luminal stenosis with angular“fishhook”changes,which changed significantly during forceful inspiration and expiration;gallbladder stones;and multiple cysts in the liver.Abdominal duplex ultrasonography showed that peak systolic velocity was 352 cm/s.After diagnosis of MALS was confirmed,an arch ligament release procedure was performed.MALS has no specific symptoms and can be misdiagnosed as other abdominal diseases.Awareness of MALS should be improved to avoid misdiagnosis.The commonly used treatment option is MAL release and resection of the peripheral ganglion of the celiac trunk artery.CONCLUSION The diagnosis and treatment of MALS must be individualized,and MAL release is effective and provides immediate symptomatic relief.
基金financially supported by the National Oil and Gas Major Project(2016ZX05047-003,2016ZX05014002-006)the National Natural Science Foundation of China(41572124)the Fundamental Research Funds for the Central Universities(17CX05010)
文摘Analysis of the in situ stress orientation and magnitude in the No.4 Structure of Nanpu Sag was performed on the basis of data obtained from borehole breakout and acoustic emission measurements.On the basis of mechanical experiments,logging interpretation,and seismic data,a 3 D geological model and heterogeneous rock mechanics field of the reservoir were constructed.Finite element simulation techniques were then used for the detailed prediction of the 3 D stress field.The results indicated that the maximum horizontal stress orientation in the study area was generally NEE-SWW trending,with significant changes in the in situ stress orientation within and between fault blocks.Along surfaces and profiles,stress magnitudes were discrete and the in situ stress belonged to theⅠa-type.Observed inter-strata differences were characterized as five different types of in situ stress profile.Faults were the most important factor causing large distributional differences in the stress field of reservoirs within the complex fault blocks.The next important influence on the stress field was the reservoir’s rock mechanics parameters,which impacted on the magnitudes of in situ stress magnitudes.This technique provided a theoretical basis for more efficient exploration and development of low-permeability reservoirs within complex fault blocks.
基金supported by China Natural Science Foundation(Grant No.51704303)Beijing Natural Science Foundation(Grant No.3173044)。
文摘The classification of low permeability-tight reservoirs is the premise of development. The deep reservoir of Shahejie 3 member contains rich low permeability-tight reserves, but the strong heterogeneity and complex micro pore structure make the main controlling factors subjective and the classification boundaries unclear. Therefore, a new indicator considering the interaction between fluid and rock named Threshold Flow Zone Indicator(TFZI) is proposed, it can be used as the main sequence of correlation analysis to screen the main controlling factors, and the clustering algorithm is optimized combined with probability distribution to determine the classification boundaries. The sorting coefficient, main throat radius, movable fluid saturation and displacement pressure are screened as the representative parameters for the following four key aspects: rock composition, microstructure, flow capacity and the interaction between rock and fluid. Compared with the traditional probability distribution and clustering algorithm, the boundary of the optimized clustering algorithm proposed in this paper is more accurate.The classification results are consistent with sedimentary facies, oil levels and oil production intensity.This method provides an important basis for the development of low permeability-tight reservoirs.
基金Project supported by the National Natural Science Foundation of China(Grant No.21972103)the National Key Research and Development Program of China(Grant No.2016YFB040183)Research and Development Program of Shanxi Province,China(Grant No.201703D111026)
文摘Low temperature(77 K)photoluminescence measurements have been performed on different GaAs substrates to evaluate the GaAs crystal quality.Several defect-related luminescence peaks have been observed,including 1.452 eV,1.476 eV,1.326 eV peaks deriving from 78 meV GaAs antisite defects,and 1.372 eV,1.289 eV peaks resulting from As vacancy related defects.Changes in photoluminescence emission intensity and emission energy as a function of temperature and excitation power lead to the identification of the defect states.The luminescence mechanisms of the defect states were studied by photoluminescence spectroscopy and the growth quality of GaAs crystal was evaluated.
基金sponsored by Strategic Priority Research Program of the Chinese Academy of Science[grant No.XDA17010106]the National Key Research and Development Program of China[grant Nos.2018YFC1505703 and 2018YFC1506704].
基金Project supported by the National Natural Science Foundation of China(No.U21A20443)。
文摘Satellite Internet of Things(IoT)is a promising way to provide seamless coverage to a massive number of devices all over the world,especially in remote areas not covered by cellular networks,e.g.,forests,oceans,mountains,and deserts.In general,satellite IoT networks take low Earth orbit(LEO)satellites as access points,which solves the problem of wide coverage,but leads to many challenging issues.We first give an overview of satellite IoT,with an emphasis on revealing the characteristics of IoT services.Then,the challenging issues of satellite IoT,i.e.,massive connectivity,wide coverage,high mobility,low power,and stringent delay,are analyzed in detail.Furthermore,the possible solutions to these challenges are provided.In particular,new massive access protocols and techniques are designed according to the characteristics and requirements of satellite IoT.Finally,we discuss several development trends of satellite IoT to stimulate and encourage further research in such a broad area.
