A meso-scale truss network model was developed to predict chloride diffusion in concrete. The model regards concrete as a three-phase composite of mortar matrix, coarse aggregates, and the interfacial transition zone ...A meso-scale truss network model was developed to predict chloride diffusion in concrete. The model regards concrete as a three-phase composite of mortar matrix, coarse aggregates, and the interfacial transition zone （ITZ） between the mortar matrix and the aggregates. The diffusion coefficient of chloride in the mortar and the ITZ can be analytically determined with only the water-to-cement ratio and volume fraction of fine aggregates. Fick＇s second law of diffusion was used as the governing equation for chloride diffusion in a homogenous medium （e.g., mortar）; it was discretized and applied to the truss network model. The solution procedure of the truss network model based on the diffusion law and the meso-scale composite structure of concrete is outlined. Additionally, the dependence of the diffusion coefficient of chloride in the mortar and the ITZ on exposure duration and temperature is taken into account to illustrate their effect on chloride diffusion coefficient. The numerical results show that the exposure duration and environmental temperature play important roles in the diffusion rate of chloride ions in concrete. It is also concluded that the meso-scale truss network model can be applied to chloride transport analysis of damaged （or cracked） concrete.展开更多
Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the sy...Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the system analysis theory and project portfolio theory, this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis. A model with multi-resource constraints, which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project, was proposed. Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out. This paper also makes suggestions for further research directions and subjects, which will be useful in improving the theories in relevant research fields.展开更多
1.Objective Lop Nur is currently one of the world’s largest playa and located in the easternmost of the Tarim Basin,northwestern China.It developed unique giant glauberite deposits during the Quaternary,of which anal...1.Objective Lop Nur is currently one of the world’s largest playa and located in the easternmost of the Tarim Basin,northwestern China.It developed unique giant glauberite deposits during the Quaternary,of which analogue with such a scale deposit is rarely seen around the world.Moreover,potassium-rich brine hosted in these glauberite intercrystalline contains a resource of KCl up to 0.25×10^(9) t.展开更多
BACKGROUND Atherosclerosis is one of the main causes of coronary artery ostial lesions seen clinically.Secondary coronary artery ostial lesions are rare,and cases reported previously were associated with syphilitic va...BACKGROUND Atherosclerosis is one of the main causes of coronary artery ostial lesions seen clinically.Secondary coronary artery ostial lesions are rare,and cases reported previously were associated with syphilitic vasculitis and aortic dissection.Here,we report three rare cases of secondary coronary ostial lesions.Due to their rareness,these lesions can easily be neglected,which may lead to misdiagnosis and missed diagnosis.CASE SUMMARY We present three patients with acute myocardial infarction and unstable angina caused by secondary coronary artery ostial lesions.In Case 1,coronary angiography(CAG)revealed 90%stenosis of the left main coronary ostium.Chest contrast computed tomography(CT)suggested thymic carcinoma invading the left main coronary ostium.Coronary artery bypass grafting and tumor resection were performed.In Case 2,echocardiography revealed a sinus of Valsalva aneurysm(SVA)-like dilatation.CAG showed a right coronary sinus giant aneurysm and complete obstruction of the right coronary artery(RCA)ostium.Aortic contrast CT confirmed these findings.The Bentall procedure was performed.In Case 3,CT CAG identified an anomalous origin of the right coronary artery(AORCA)from the left sinus of Valsalva coursing between the aorta and pulmonary trunk,causing severe RCA ostium stenosis by compression.Surgical correction of the AORCA was performed.CONCLUSION The cases reported here suggest that we should consider other causes of coronary ostial lesions other than atherosclerosis.展开更多
Exceptional points(EPs),which are typically defined as the degener-acy points of a non-Hermitian Hamiltonian,have been investigated in various physical systems such as photonic systems.In particular,the intriguing top...Exceptional points(EPs),which are typically defined as the degener-acy points of a non-Hermitian Hamiltonian,have been investigated in various physical systems such as photonic systems.In particular,the intriguing topological structures around EPs have given rise to novel strategies for manipulating photons and the underlying mechanism is especially useful for on-chip photonic applications.Although some on-chip experiments with the adoption of lasers have been reported,EP-based photonic chips working in the quantum regime largely re-main elusive.In the current work,a single-photon experiment was proposed to dynamically encircle an EP in on-chip photonic waveg-uides possessing passive anti-parity-time symmetry.Photon coinci-dences measurement reveals a chiral feature of transporting single photons,which can act as a building block for on-chip quantum de-vices that require asymmetric transmissions.The findings in the cur-rent work pave the way for on-chip experimental study on the physics of EPs as well as inspiring applications for on-chip non-Hermitian quantum devices.展开更多
基金supported by the Key Project of the Chinese Ministry of Education (Grant No. 109046)the Center for Concrete Corea, Korea of the Yonsei University of Korea, the Grant-in-Aid for Scientific Research from the Japanese Government (A) (Grant No. 19206048)
文摘A meso-scale truss network model was developed to predict chloride diffusion in concrete. The model regards concrete as a three-phase composite of mortar matrix, coarse aggregates, and the interfacial transition zone （ITZ） between the mortar matrix and the aggregates. The diffusion coefficient of chloride in the mortar and the ITZ can be analytically determined with only the water-to-cement ratio and volume fraction of fine aggregates. Fick＇s second law of diffusion was used as the governing equation for chloride diffusion in a homogenous medium （e.g., mortar）; it was discretized and applied to the truss network model. The solution procedure of the truss network model based on the diffusion law and the meso-scale composite structure of concrete is outlined. Additionally, the dependence of the diffusion coefficient of chloride in the mortar and the ITZ on exposure duration and temperature is taken into account to illustrate their effect on chloride diffusion coefficient. The numerical results show that the exposure duration and environmental temperature play important roles in the diffusion rate of chloride ions in concrete. It is also concluded that the meso-scale truss network model can be applied to chloride transport analysis of damaged （or cracked） concrete.
基金supported by the National Science and Technology Plan (Major Project of the Eleventh Five-Year Plan,Grant No. 2006BAB04A13)the Philosophy and Social Science Fund of the Education Department of Jiangsu Province (Grant No.07SJD630006)+2 种基金the Third Key Discipline (Techno-Economics and Management) of the 211 Projectthe Key Discipline of Jiangsu Province (Engineering and Project Management)the Office of the South-to-North Water Diversion Project Construction Committee under the State Council
文摘Recently, the critical chain study has become a hot issue in the project management research field. The construction of the critical chain with multi-resource constraints is a new research subject. According to the system analysis theory and project portfolio theory, this paper discusses the creation of project portfolios based on the similarity principle and gives the definition of priority in multi-resource allocation based on quantitative analysis. A model with multi-resource constraints, which can be applied to the critical chain construction of the A-bid section in the South-to-North Water Diversion Project, was proposed. Contrast analysis with the comprehensive treatment construction method and aggressive treatment construction method was carried out. This paper also makes suggestions for further research directions and subjects, which will be useful in improving the theories in relevant research fields.
基金This research is supported by the National Natural Science Foundation of China(41972092,40830420,41702097)the Scientific and Technical project of SDIC Xinjiang Luobupo Potash Co.,LTD..
文摘1.Objective Lop Nur is currently one of the world’s largest playa and located in the easternmost of the Tarim Basin,northwestern China.It developed unique giant glauberite deposits during the Quaternary,of which analogue with such a scale deposit is rarely seen around the world.Moreover,potassium-rich brine hosted in these glauberite intercrystalline contains a resource of KCl up to 0.25×10^(9) t.
文摘BACKGROUND Atherosclerosis is one of the main causes of coronary artery ostial lesions seen clinically.Secondary coronary artery ostial lesions are rare,and cases reported previously were associated with syphilitic vasculitis and aortic dissection.Here,we report three rare cases of secondary coronary ostial lesions.Due to their rareness,these lesions can easily be neglected,which may lead to misdiagnosis and missed diagnosis.CASE SUMMARY We present three patients with acute myocardial infarction and unstable angina caused by secondary coronary artery ostial lesions.In Case 1,coronary angiography(CAG)revealed 90%stenosis of the left main coronary ostium.Chest contrast computed tomography(CT)suggested thymic carcinoma invading the left main coronary ostium.Coronary artery bypass grafting and tumor resection were performed.In Case 2,echocardiography revealed a sinus of Valsalva aneurysm(SVA)-like dilatation.CAG showed a right coronary sinus giant aneurysm and complete obstruction of the right coronary artery(RCA)ostium.Aortic contrast CT confirmed these findings.The Bentall procedure was performed.In Case 3,CT CAG identified an anomalous origin of the right coronary artery(AORCA)from the left sinus of Valsalva coursing between the aorta and pulmonary trunk,causing severe RCA ostium stenosis by compression.Surgical correction of the AORCA was performed.CONCLUSION The cases reported here suggest that we should consider other causes of coronary ostial lesions other than atherosclerosis.
基金supported by National Natural Sci-ence Foundation of China(NSFC)under Grants 61825502,11974140 and#61827826Scientific and Technological Development Plan Program of Jilin Province(SKL202302012)Work done in Hong Kong was supported by RGC Hong Kong(N_HKUST608/17,AoE/P-502/20 and C6013-18G-A)and by the Croucher Foundation.
文摘Exceptional points(EPs),which are typically defined as the degener-acy points of a non-Hermitian Hamiltonian,have been investigated in various physical systems such as photonic systems.In particular,the intriguing topological structures around EPs have given rise to novel strategies for manipulating photons and the underlying mechanism is especially useful for on-chip photonic applications.Although some on-chip experiments with the adoption of lasers have been reported,EP-based photonic chips working in the quantum regime largely re-main elusive.In the current work,a single-photon experiment was proposed to dynamically encircle an EP in on-chip photonic waveg-uides possessing passive anti-parity-time symmetry.Photon coinci-dences measurement reveals a chiral feature of transporting single photons,which can act as a building block for on-chip quantum de-vices that require asymmetric transmissions.The findings in the cur-rent work pave the way for on-chip experimental study on the physics of EPs as well as inspiring applications for on-chip non-Hermitian quantum devices.
