燃气蒸汽联合循环(natural gas combined cycle,NGCC)具有清洁、高效、部分变负荷能力强等特点,将NGCC机组与碳捕集系统耦合是实现碳减排的重要途径之一。以国际能源署(International Energy Agency,IEA)报告中的884 MW二拖一燃气蒸汽...燃气蒸汽联合循环(natural gas combined cycle,NGCC)具有清洁、高效、部分变负荷能力强等特点,将NGCC机组与碳捕集系统耦合是实现碳减排的重要途径之一。以国际能源署(International Energy Agency,IEA)报告中的884 MW二拖一燃气蒸汽联合循环机组为参考对象,利用Ebsilon软件对其进行建模验证。基于能量梯级利用原则,提出了4个不同的NGCC机组与碳捕集系统耦合方案,分别是抽汽回除氧器、抽汽换热回除氧器,抽汽回凝汽器以及增设小汽机加回热回除氧器。并进一步分析了4种不同耦合方案的热力性能,其能量惩罚分别为6.67%、6.59%、 6.81%和5.46%,得出方案4能有效降低能量惩罚。展开更多
A great improvement on a previous work (Phys. Rev. B48 (1993) 14067) has been made. By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as a...A great improvement on a previous work (Phys. Rev. B48 (1993) 14067) has been made. By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d<SUP>3</SUP> electronic configuration, the values of all the parameters in the expressions of thermal shift (TS) and thermal broadening (TB) from EPI for the ground level, R level and R line of MgO:V<SUP>2+</SUP> have microscopically been evaluated; and then, both the TS and TB of R line and various contributions to them have uniformly been calculated. The results are in very good agreement with the experimental data. It is found that all the three terms of TS from EPI are red shifts; the term of the contribution to TS from thermal expansion is blue shift. The Raman term is the largest, and the other terms are also important for TS. The R-line TS of MgO:V<SUP>2+</SUP> comes from the first-order term of EPI. The elastic Raman scattering of acoustic phonons plays a dominant role in R-line TB of MgO:V<SUP>2+</SUP>. For calculations of both the TS and TB, it is very important to take into account all the admixtures of wavefunctions.展开更多
For the first timc, by taking into account all the irreducible representations and their components in theelectron-phonon interaction (EPI) as well as all the levels and the admixtures of wavefunctions within d3 elect...For the first timc, by taking into account all the irreducible representations and their components in theelectron-phonon interaction (EPI) as well as all the levels and the admixtures of wavefunctions within d3 electronicconfiguration, the values of parameters in expressions of Raman and optical-branch terms of thermal shifts (TS) due toEPI for three levels, 4T2 band and 4T1 band of ruby have been evaluated; the contributions to TS of 4T2 and 4T1 broadbands from thermal expansion have also been calculated; and then, the TS of the peak energies of 4T2 and 4T1 broadbands have been calculated. The results are in satisfactory agreement with observed data. The values of single-electronreduced matrix elements representing the strengths of EPI of 4T2 and 4T1 bands have respectively been determined. ForTS of the peak energies of 4T2 and 4T1 bands, it is found that the contribution to TS from the second-order term in EPIHamiltonian is dominant; TS due to EPI of acoustic branches are over two times as much as those of optical branches,and both of them increase rapidly with temperature; the neighbor-level term is insignificant; the contribution to TS fromthermal expansion is specially important, and all the three terms of TS of 4T2 or 4T1 band are red shifts.展开更多
Under various uniaxial stresses,both strains with low symmetry and isotropic strains of crystals take place.The former fives the strain-induced low-symmetry crystal fields and accordingly splittings of levels;the latt...Under various uniaxial stresses,both strains with low symmetry and isotropic strains of crystals take place.The former fives the strain-induced low-symmetry crystal fields and accordingly splittings of levels;the latter gives the isotropic parts of strain-induced crystal fields and accordingly shifts of levels.By using the wavefunctions obtained from the diagonalization of the complete d^3 energy matrix in a regular octahedral field,the relevant matrix elements and accordingly strain-induced splittings and/or shifts of t2^32E and t2^34A2 for MgO:Cr^3+ have been calculated.Their physical origins have been thoroughly analyzed and revealed.It is the admixtures of basic wavefunctions resulted from the spinorbit interaction and/ork Coulomb interaction and/or Kramers degeneracy that make strain-induced splittings of levels nonzero.In contrast with this,strain-induced shifts come mainly from the zero-order approximate wavefunctions.It is found that there are nonvanishing matrix elements of operators T2ξ,T2η and T2ζ between wavefunctions with positive Ms and those with negative ms',which have important effects on strain-induced splittings of levels.The shifts of t2^32E under both hydrostatic pressure and uniaxial pressure have been uniformly calculated.The important results of Yc,Zc,Pc,Qc and <t2||C(A1)||t2> have been evaluated.展开更多
By making use of the diagonalization of the complete d3 energy matrix in a trigonally distorted cubic-field and the theory of pressure-induced shifts (PS) of energy spectra, the whole energy spectrum of α-Al2 O3 :Mn4...By making use of the diagonalization of the complete d3 energy matrix in a trigonally distorted cubic-field and the theory of pressure-induced shifts (PS) of energy spectra, the whole energy spectrum of α-Al2 O3 :Mn4+ and PS of levels have been calculated. All the calculated results are in excellent agreement with the experimental data. The comparison between the results ofα-AlO3:Mn4+ and ruby has been made. It is found that on one hand, R1-line and R2line PS of α-Al2O3:Mn4+ and ruby are linear in pressure over 0 ～ 100 kbar, and their values of the principal parameter for PS are very close to each other. On the other hand, the sensitivities of R1-line and R2-line PS of α-Al2O3:Mn4+are higher than those of ruby respectively, which comes mainly from the difference between the values of parameters at normal pressure of two crystals; moreover, the expansion ofd-electron wavefunctions of α-Al2 O3 :Mn4+ with compression is slightly larger than the one of ruby, and the effective charge experienced by d-electrons of α-Al2O3:Mn4+ decreases with compression more rapidly than the one of ruby. In the final analysis, all these can be explained in terms of the facts that the two crystals are doped α-Al2O3 with two isoelectronic ions; the strengths of the crystal field and covalency of α-Al2O3 :Mn4+ are larger than those of ruby respectively, due to the charge of Mn4+ to be larger than that of Cr3+.展开更多
背景与目的:随着微创理念及技术的发展,经腹腔镜完成腹壁切口疝手术已成为趋势,但由于腹壁切口疝位置大小不定,暂无成熟的布孔方法供术者参考,使得手术术式的学习难度较大,不合理的布孔还易导致手术难度加大。笔者在此介绍一种基于数据...背景与目的:随着微创理念及技术的发展,经腹腔镜完成腹壁切口疝手术已成为趋势,但由于腹壁切口疝位置大小不定,暂无成熟的布孔方法供术者参考,使得手术术式的学习难度较大,不合理的布孔还易导致手术难度加大。笔者在此介绍一种基于数据分析与计算的模型化布孔方法,并通过与传统经验性布孔法进行比较,探讨其优势和临床效果。方法:选择2017年1月—2018年5月中山大学附属第六医院收治并拟行腹腔内补片植入术(IPOM)的44例腹壁切口疝患者,用随机数字表法将患者分为对照组(21例)和研究组(23例),对照组采用术中放置观察孔后以手术经验放置操作孔的布孔方法,研究组采用术前腹部轮廓分析,并按照步骤划定限制条件,根据操作器械尺寸计算合理距离的方法指导穿刺孔放置位置的方法。比较两组患者术中及术后的相关临床指标。结果:两组患者一般资料差异无统计学意义(均P>0.05)。与对照组比较,研究组的平均布孔时间(7.28 min vs.9.93 min)、平均手术时间(67.62 min vs.79.10 min)、术中加孔率(17%vs.48%)均明显减少(均P<0.05)。研究组与对照组患者的术后并发症发生率(4.3%vs.19.0%),术后住院时间(5.13 d vs.5.76 d)及术后复发率(4.3%vs.4.8%)差异均无统计学意义(均P>0.05)。结论:在腹腔镜腹壁切口疝IPOM手术采用模型化布孔法可以缩短布孔时间,合理的操作孔布置可以降低腹腔镜下粘连分离、缺损缝合及补片固定的难度,降低手术总时间及术中增加操作孔的几率,并不增加术后并发症发生率,住院时间及复发疝的几率。模型化布孔法以客观数据+定量计算代替传统布孔法的经验决策,在方法步骤上更明晰,并可以在使用中不断更新改进,将有助于腹腔镜腹壁切口疝手术的规范与推广。展开更多
文摘燃气蒸汽联合循环(natural gas combined cycle,NGCC)具有清洁、高效、部分变负荷能力强等特点,将NGCC机组与碳捕集系统耦合是实现碳减排的重要途径之一。以国际能源署(International Energy Agency,IEA)报告中的884 MW二拖一燃气蒸汽联合循环机组为参考对象,利用Ebsilon软件对其进行建模验证。基于能量梯级利用原则,提出了4个不同的NGCC机组与碳捕集系统耦合方案,分别是抽汽回除氧器、抽汽换热回除氧器,抽汽回凝汽器以及增设小汽机加回热回除氧器。并进一步分析了4种不同耦合方案的热力性能,其能量惩罚分别为6.67%、6.59%、 6.81%和5.46%,得出方案4能有效降低能量惩罚。
文摘A great improvement on a previous work (Phys. Rev. B48 (1993) 14067) has been made. By taking into account all the irreducible representations and their components in the electron-phonon interaction (EPI) as well as all the levels and the admixtures of basic wavefunctions within d<SUP>3</SUP> electronic configuration, the values of all the parameters in the expressions of thermal shift (TS) and thermal broadening (TB) from EPI for the ground level, R level and R line of MgO:V<SUP>2+</SUP> have microscopically been evaluated; and then, both the TS and TB of R line and various contributions to them have uniformly been calculated. The results are in very good agreement with the experimental data. It is found that all the three terms of TS from EPI are red shifts; the term of the contribution to TS from thermal expansion is blue shift. The Raman term is the largest, and the other terms are also important for TS. The R-line TS of MgO:V<SUP>2+</SUP> comes from the first-order term of EPI. The elastic Raman scattering of acoustic phonons plays a dominant role in R-line TB of MgO:V<SUP>2+</SUP>. For calculations of both the TS and TB, it is very important to take into account all the admixtures of wavefunctions.
文摘For the first timc, by taking into account all the irreducible representations and their components in theelectron-phonon interaction (EPI) as well as all the levels and the admixtures of wavefunctions within d3 electronicconfiguration, the values of parameters in expressions of Raman and optical-branch terms of thermal shifts (TS) due toEPI for three levels, 4T2 band and 4T1 band of ruby have been evaluated; the contributions to TS of 4T2 and 4T1 broadbands from thermal expansion have also been calculated; and then, the TS of the peak energies of 4T2 and 4T1 broadbands have been calculated. The results are in satisfactory agreement with observed data. The values of single-electronreduced matrix elements representing the strengths of EPI of 4T2 and 4T1 bands have respectively been determined. ForTS of the peak energies of 4T2 and 4T1 bands, it is found that the contribution to TS from the second-order term in EPIHamiltonian is dominant; TS due to EPI of acoustic branches are over two times as much as those of optical branches,and both of them increase rapidly with temperature; the neighbor-level term is insignificant; the contribution to TS fromthermal expansion is specially important, and all the three terms of TS of 4T2 or 4T1 band are red shifts.
文摘Under various uniaxial stresses,both strains with low symmetry and isotropic strains of crystals take place.The former fives the strain-induced low-symmetry crystal fields and accordingly splittings of levels;the latter gives the isotropic parts of strain-induced crystal fields and accordingly shifts of levels.By using the wavefunctions obtained from the diagonalization of the complete d^3 energy matrix in a regular octahedral field,the relevant matrix elements and accordingly strain-induced splittings and/or shifts of t2^32E and t2^34A2 for MgO:Cr^3+ have been calculated.Their physical origins have been thoroughly analyzed and revealed.It is the admixtures of basic wavefunctions resulted from the spinorbit interaction and/ork Coulomb interaction and/or Kramers degeneracy that make strain-induced splittings of levels nonzero.In contrast with this,strain-induced shifts come mainly from the zero-order approximate wavefunctions.It is found that there are nonvanishing matrix elements of operators T2ξ,T2η and T2ζ between wavefunctions with positive Ms and those with negative ms',which have important effects on strain-induced splittings of levels.The shifts of t2^32E under both hydrostatic pressure and uniaxial pressure have been uniformly calculated.The important results of Yc,Zc,Pc,Qc and <t2||C(A1)||t2> have been evaluated.
文摘By making use of the diagonalization of the complete d3 energy matrix in a trigonally distorted cubic-field and the theory of pressure-induced shifts (PS) of energy spectra, the whole energy spectrum of α-Al2 O3 :Mn4+ and PS of levels have been calculated. All the calculated results are in excellent agreement with the experimental data. The comparison between the results ofα-AlO3:Mn4+ and ruby has been made. It is found that on one hand, R1-line and R2line PS of α-Al2O3:Mn4+ and ruby are linear in pressure over 0 ～ 100 kbar, and their values of the principal parameter for PS are very close to each other. On the other hand, the sensitivities of R1-line and R2-line PS of α-Al2O3:Mn4+are higher than those of ruby respectively, which comes mainly from the difference between the values of parameters at normal pressure of two crystals; moreover, the expansion ofd-electron wavefunctions of α-Al2 O3 :Mn4+ with compression is slightly larger than the one of ruby, and the effective charge experienced by d-electrons of α-Al2O3:Mn4+ decreases with compression more rapidly than the one of ruby. In the final analysis, all these can be explained in terms of the facts that the two crystals are doped α-Al2O3 with two isoelectronic ions; the strengths of the crystal field and covalency of α-Al2O3 :Mn4+ are larger than those of ruby respectively, due to the charge of Mn4+ to be larger than that of Cr3+.
文摘背景与目的:随着微创理念及技术的发展,经腹腔镜完成腹壁切口疝手术已成为趋势,但由于腹壁切口疝位置大小不定,暂无成熟的布孔方法供术者参考,使得手术术式的学习难度较大,不合理的布孔还易导致手术难度加大。笔者在此介绍一种基于数据分析与计算的模型化布孔方法,并通过与传统经验性布孔法进行比较,探讨其优势和临床效果。方法:选择2017年1月—2018年5月中山大学附属第六医院收治并拟行腹腔内补片植入术(IPOM)的44例腹壁切口疝患者,用随机数字表法将患者分为对照组(21例)和研究组(23例),对照组采用术中放置观察孔后以手术经验放置操作孔的布孔方法,研究组采用术前腹部轮廓分析,并按照步骤划定限制条件,根据操作器械尺寸计算合理距离的方法指导穿刺孔放置位置的方法。比较两组患者术中及术后的相关临床指标。结果:两组患者一般资料差异无统计学意义(均P>0.05)。与对照组比较,研究组的平均布孔时间(7.28 min vs.9.93 min)、平均手术时间(67.62 min vs.79.10 min)、术中加孔率(17%vs.48%)均明显减少(均P<0.05)。研究组与对照组患者的术后并发症发生率(4.3%vs.19.0%),术后住院时间(5.13 d vs.5.76 d)及术后复发率(4.3%vs.4.8%)差异均无统计学意义(均P>0.05)。结论:在腹腔镜腹壁切口疝IPOM手术采用模型化布孔法可以缩短布孔时间,合理的操作孔布置可以降低腹腔镜下粘连分离、缺损缝合及补片固定的难度,降低手术总时间及术中增加操作孔的几率,并不增加术后并发症发生率,住院时间及复发疝的几率。模型化布孔法以客观数据+定量计算代替传统布孔法的经验决策,在方法步骤上更明晰,并可以在使用中不断更新改进,将有助于腹腔镜腹壁切口疝手术的规范与推广。
