Consider the real, simply-connected, connected, s-step nilpotent Lie group G endowed with a left-invariant, integrable almost complex structure J, which is nilpotent. Consider the simply-connected, connected nilpotent...Consider the real, simply-connected, connected, s-step nilpotent Lie group G endowed with a left-invariant, integrable almost complex structure J, which is nilpotent. Consider the simply-connected, connected nilpotent Lie group Gk, defined by the nilpotent Lie algebra g/ak, where g is the Lie algebra of G, and ak is an ideal of g. Then, J gives rise to an almost complex structure Jk on Gk. The main conclusion obtained is as follows: if the almost complex structure J of a nilpotent Lie group G is nilpotent, then J can give rise to a left-invariant integrable almost complex structure Jk on the nilpotent Lie group Gk, and Jk is also nilpotent.展开更多
Electromagnetic logging while drilling(LWD)is one of the key technologies of the geosteering and formation evaluation for high-angle and horizontal wells.In this paper,we solve the dipole source-generated magnetic/ele...Electromagnetic logging while drilling(LWD)is one of the key technologies of the geosteering and formation evaluation for high-angle and horizontal wells.In this paper,we solve the dipole source-generated magnetic/electric fields in 2D formations efficiently by the 2.5D finite diff erence method.Particularly,by leveraging the field’s rapid attenuation in spectral domain,we propose truncated Gauss–Hermite quadrature,which is several tens of times faster than traditional inverse fast Fourier transform.By applying the algorithm to the LWD modeling under complex formations,e.g.,folds,fault and sandstone pinch-outs,we analyze the feasibility of the dimension reduction from 2D to 1D.For the formations with smooth lateral changes,like folds,the simplified 1D model’s results agree well with the true responses,which indicate that the 1D simplification with sliding window is feasible.However,for the formation structures with drastic rock properties changes and sharp boundaries,for instance,faults and sandstone pinch-outs,the simplified 1D model will lead to large errors and,therefore,2.5D algorithms should be applied to ensure the accuracy.展开更多
The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a ...The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.展开更多
At present,the optimization of the plunger mechanism is shale gas wells is mostly based on empirical methods,which lack a relevant rationale and often are not able to deal with the quick variations experienced by the ...At present,the optimization of the plunger mechanism is shale gas wells is mostly based on empirical methods,which lack a relevant rationale and often are not able to deal with the quick variations experienced by the production parameters of shale gas wells in comparison to conventional gas wells.In order to mitigate this issue,in the present work,a model is proposed to loosely couple the dynamics of gas inflow into shale gas wells with the dynamics of the liquid inflow.Starting from the flow law that accounts for the four stages of movement of the plunger,a dynamic model of the plunger lift based on the real wellbore trajectory is introduced.The model is then tested against 5 example wells,and it is shown that the accuracy level is higher than 90%.The well‘switch’,optimized on the basis of simulations based on such a model,is tested through on-site experiments.It is shown that,compared with the original switch configuration,the average production of the sample well can be increased by about 15%.展开更多
The surrounding geological conditions and supporting structures of underground engineering are often updated during construction,and these updates require repeated numerical modeling.To improve the numerical modeling ...The surrounding geological conditions and supporting structures of underground engineering are often updated during construction,and these updates require repeated numerical modeling.To improve the numerical modeling efficiency of underground engineering,a modularized and parametric modeling cloud server is developed by using Python codes.The basic framework of the cloud server is as follows:input the modeling parameters into the web platform,implement Rhino software and FLAC3D software to model and run simulations in the cloud server,and return the simulation results to the web platform.The modeling program can automatically generate instructions that can run the modeling process in Rhino based on the input modeling parameters.The main modules of the modeling program include modeling the 3D geological structures,the underground engineering structures,and the supporting structures as well as meshing the geometric models.In particular,various cross-sections of underground caverns are crafted as parametricmodules in themodeling program.Themodularized and parametric modeling program is used for a finite element simulation of the underground powerhouse of the Shuangjiangkou Hydropower Station.This complicatedmodel is rapidly generated for the simulation,and the simulation results are reasonable.Thus,this modularized and parametric modeling program is applicable for three-dimensional finite element simulations and analyses.展开更多
Vertical forest structure is closely linked to multiple ecosystem characteristics,such as biodiversity,habitat,and productivity.Mixing tree species in planted forests has the potential to create diverse vertical fores...Vertical forest structure is closely linked to multiple ecosystem characteristics,such as biodiversity,habitat,and productivity.Mixing tree species in planted forests has the potential to create diverse vertical forest structures due to the different physiological and morphological traits of the composing tree species.However,the relative importance of species richness,species identity and species interactions for the variation in vertical forest structure remains unclear,mainly because traditional forest inventories do not observe vertical stand structure in detail.Terrestrial laser scanning(TLS),however,allows to study vertical forest structure in an unprecedented way.Therefore,we used TLS single scan data from 126 plots across three experimental planted forests of a largescale tree diversity experiment in Belgium to study the drivers of vertical forest structure.These plots were 9–11years old young pure and mixed forests,characterized by four levels of tree species richness ranging from monocultures to four-species mixtures,across twenty composition levels.We generated vertical plant profiles from the TLS data and derived six stand structural variables.Linear mixed models were used to test the effect of species richness on structural variables.Employing a hierarchical diversity interaction modelling framework,we further assessed species identity effect and various species interaction effects on the six stand structural variables.Our results showed that species richness did not significantly influence most of the stand structure variables,except for canopy height and foliage height diversity.Species identity on the other hand exhibited a significant impact on vertical forest structure across all sites.Species interaction effects were observed to be site-dependent due to varying site conditions and species pools,and rapidly growing tree species tend to dominate these interactions.Overall,our results highlighted the importance of considering both species identity and interaction effects in choosing suitable species combinations for forest management practices aimed at enhancing vertical forest structure.展开更多
In this paper,we revisit the Kahler structures on the affine quadrics M1={z_(1)^(2)+z_(2)^(2)+z_(3)^(2)=1}in the paper by Bo Yang and Fang-Yang Zheng.We found that the Kahler structures on the complex surface are more...In this paper,we revisit the Kahler structures on the affine quadrics M1={z_(1)^(2)+z_(2)^(2)+z_(3)^(2)=1}in the paper by Bo Yang and Fang-Yang Zheng.We found that the Kahler structures on the complex surface are more complicated than what they have thought.We shall also give some detail calculations and found that our results fit quite well with earlier papers of the first author,one of them with X.X.Chen.展开更多
In this paper, the X-ray nondestructive test method of small defects in precision weldments with complex structure was presented. To resolve the difficulty of defect segmentation in variable grey image, the image proc...In this paper, the X-ray nondestructive test method of small defects in precision weldments with complex structure was presented. To resolve the difficulty of defect segmentation in variable grey image, the image processing based on Visual Basic programming method was adopted. The methods of automatic contrast and partial grey stretch were used to enhance the X-ray detection image which has relatively low contrast, then automatic threshold method was carried out to segment the two high intensity zones, and weld zones which contain the small defects was extracted. Smoothing and sharpen processing were proceeded on the extracted weld zones, and small defects in X-ray detection image of weldments with complex structure were segmented by using the method of background subtraction in the end. The effects of raster were eliminated, and because of that the image processing was only proceeded on the extracted weld zones, the calculated speed using the above provided algorithm was improved.展开更多
Inclusion compound of retinoic acid with (-cyclodextrin was prepared by coprecipitating method, the structure of resulting product was studied by elemental analysis, differential scanning caloriemetry(DSC) analysis, F...Inclusion compound of retinoic acid with (-cyclodextrin was prepared by coprecipitating method, the structure of resulting product was studied by elemental analysis, differential scanning caloriemetry(DSC) analysis, FT-IR spectroscopy and X-ray diffractometry, and the formed supramolecule self-assembles in aqueous solution according to molar ratio 2:1 of host-guest.展开更多
One complex with a zwitterionic dicarboxylate ligand, [Mn(L)(N3)]n 1 (L = 1-car- boxymethylpyridinium-3-carboxylate), was synthesized and structurally characterized. Complex 1 crystallizes in triclinic, space gr...One complex with a zwitterionic dicarboxylate ligand, [Mn(L)(N3)]n 1 (L = 1-car- boxymethylpyridinium-3-carboxylate), was synthesized and structurally characterized. Complex 1 crystallizes in triclinic, space group P1 with a = 7.570(2), b = 7.808(2), c = 9.232(3) A, β= 94.450(19)°, V= 489.0(3) A3, Z = 2, Mr = 277.11, Dc = 1.882 g/cm3, F(000) = 278,μ = 1.359 mm-1, S = 1.021, the final R = 0.0509 and wR = 0.1149 for 2236 observed reflections with 1 〉 2σ(I). Complex 1 consists of two-dimensional coordination layers in which the anionic uniform chains with mixed triple bridges (one end-on (EO) azide and two syn-syn carboxylates) are cross-linked by the flexible cationic N-methylpyridinium spacers. Magnetic studies demonstrated that the triple bridge in 1 transmits antiferromagnetic coupling between the Mn(Ⅱ) ions.展开更多
The main purpose of this note is to construct almost complex or complex structures on certain isoparametric hypersurfaces in unit spheres.As a consequence,complex structures on S^(1)×S^(7)×S^(6),and on S^(10...The main purpose of this note is to construct almost complex or complex structures on certain isoparametric hypersurfaces in unit spheres.As a consequence,complex structures on S^(1)×S^(7)×S^(6),and on S^(10)×S^(3)×S(2)with vanishing first Chern class,are built.展开更多
Heat shock proteins(Hsps)are a family of abundantly expressed ATP-dependent chaperone proteins.Hsp90 is an eminent member of Hsp family.Thus far,two primary functions have been described for Hsp90:first,as a regulator...Heat shock proteins(Hsps)are a family of abundantly expressed ATP-dependent chaperone proteins.Hsp90 is an eminent member of Hsp family.Thus far,two primary functions have been described for Hsp90:first,as a regulator of conformational change of some protein kinases and nuclear hormone receptors,and the other as an indispensable factor in cellular stress response.Hsp90 has an essential number of interaction proteins since it participates in almost every biological process and its importance is self-evident.Hsp90 has an inextricable relationship in the pathogenesis of cancer,especially in the proliferation and irradiation of cancer cells,thus being a notable cancer target.Since the discovery of geldanamycin,the first inhibitor of Hsp90,from the bacterial species Streptomyces hygroscopicus,even more attention has been focused toward Hsp90.Many structure-based inhibitors of Hsp90 have been designed to develop an innovative method to defeat cancer.However,already designed inhibitors have various deficiencies,such as hepatotoxicity,poor aqueous solubility,instability,and non-ideal oral bioavailability.Based on the aforementioned reasons and to achieve an optimal performance and fewer side effects,we designed a novel inhibitor of Hsp90,called FS5,and resolved the crystal structure of the Hsp90^N-FS5 complex(1.65 A°,PDB code 5XRB).Furthermore,we compared the complexes Hsp90^N,Hsp90^N-GDM,and Hsp90^N-ATP and suggest that the inhibitor FS5 may compete with ATP for binding to Hsp90,which can be regarded as a potential strategy for the development of novel cancer drugs in the future.展开更多
Using a tight binding transfer matrix method, we calculate the complex band structure of armchair graphene nanoribbons. The real part of the complex band structure calculated by the transfer matrix method fits well wi...Using a tight binding transfer matrix method, we calculate the complex band structure of armchair graphene nanoribbons. The real part of the complex band structure calculated by the transfer matrix method fits well with the bulk band structure calculated by a Hermitian matrix. The complex band structure gives extra information on carrier's decay behaviour. The imaginary loop connects the conduction and valence band, and can profoundly affect the characteristics of nanoscale electronic device made with graphene nanoribbons. In this work, the complex band structure calculation includes not only the first nearest neighbour interaction, but also the effects of edge bond relaxation and the third nearest neighbour interaction. The band gap is classified into three classes. Due to the edge bond relaxation and the third nearest neighbour interaction term, it opens a band gap for N = 3M- 1. The band gap is almost unchanged for N =3M + 1, but decreased for N = 3M. The maximum imaginary wave vector length provides additional information about the electrical characteristics of graphene nanoribbons, and is also classified into three classes.展开更多
The crystal structure of one novel Mn(II) complex, [Mn(pmta)_3]_2[Mn(H_2O)_6]·4H_2O(1), is reported(Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid). In the title compound, the asymmetric ...The crystal structure of one novel Mn(II) complex, [Mn(pmta)_3]_2[Mn(H_2O)_6]·4H_2O(1), is reported(Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid). In the title compound, the asymmetric unit consists of a [Mn(pmta_)3]ˉ anion, half [Mn(H_2O)_6]^(2+) counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.展开更多
The two complexes [HgI_2L](DMF)(1) and [AgL_2](ClO_4)(CH_3CN)(2) were synthesized from the reaction of Schiff base ligand(2-acetylpyridine-p-aminobenzoylhydrazone)(L) with HgI_2 or AgClO_4 respectively. ...The two complexes [HgI_2L](DMF)(1) and [AgL_2](ClO_4)(CH_3CN)(2) were synthesized from the reaction of Schiff base ligand(2-acetylpyridine-p-aminobenzoylhydrazone)(L) with HgI_2 or AgClO_4 respectively. The compounds are characterized by ^1H NMR,FTIR and elemental analysis. The structures of the ligand and two complexes are measured via single-crystal X-ray diffraction. In these two complexes,the structures are both distorted triangular bipyramids with five-coordinated centers.展开更多
With transition metal complex, a discrete cuprous iodide compound, namely, [Ni(phen)3]2Cu6I10(1, phen = 1,10-phenanthroline) has been solvothermally synthesized and structurally characterized. Single-crystal X-ray...With transition metal complex, a discrete cuprous iodide compound, namely, [Ni(phen)3]2Cu6I10(1, phen = 1,10-phenanthroline) has been solvothermally synthesized and structurally characterized. Single-crystal X-ray diffraction studies revealed that compound 1 crystallizes in triclinic space group P1(No. 2) with a = 11.2694(2), b = 12.3699(3), c = 15.0387(3) ?, α = 102.840(2), β = 105.215(2), γ = 96.388(2)°, V = 1940.04(7) ^3, Z = 1, Dc = 2.438 g·cm^-3, F(000) = 1324, R = 0.0256 and w R = 0.0555(I 〉 2σ(I)). Compound 1 features a discrete anionic moiety of [Cu6I10]^4- charge-balanced by two metal complexes of [Ni(phen)3]2+. The optical absorption edge of compound 1 was estimated to be 2.24 eV. Interestingly, nearly 95% of contaminant(crystal violet aqueous solution(CV), 50 m L, 1.0 × 10^-5 M) could be decolorized after exposure to visible light within 30 min, illustrating an impressive photocatalytic activity of compound 1. The thermal stability of 1 has also been studied.展开更多
A new structure with the molecular formula [CdL]n was formed by CdSO4 with 4-carboxymethoxy phenylacetic acid (H2L) through the hydrothermal method. The complex was characterized by elemental analysis and infrared s...A new structure with the molecular formula [CdL]n was formed by CdSO4 with 4-carboxymethoxy phenylacetic acid (H2L) through the hydrothermal method. The complex was characterized by elemental analysis and infrared spectroscopy. The structure of the complex was determined by single-crystal X-ray diffraction, which is of monoclinic system, space group P21/c with a = 10.3887(2), b = 7.10710(10), c = 14.7212(2) , β = 120.6940(10)°, V = 934.65(3) 3, Dc = 2.278 g·cm-3, Z = 4, F(000) = 624, S = 1.022, the final R = 0.0187 and wR = 0.0487 for 2000 observer reflections (Ⅰ 〉 2σ(Ⅰ)). The center metal ion Cd(Ⅱ) in the complex is six-coordinated in a distorted octahedral geometry, and is connected with L ligands to form a 3D fishing net structure, which is a novel (3,6) network topology. The luminescence of the complex has been investigated, and the result reveals that it displays luminescent property in the voilet region.展开更多
The title complex bis{4-chloro-2-[(6-methyl-pyridin-2-ylimino)-methyl]-phenol}-palladium(Ⅱ)(C_(26)H_(20)Cl_2N_4O_2Pd) has been synthesized by the reaction of 4-chloro-2-[(6-methylpyridin- 2-ylimino)-methy...The title complex bis{4-chloro-2-[(6-methyl-pyridin-2-ylimino)-methyl]-phenol}-palladium(Ⅱ)(C_(26)H_(20)Cl_2N_4O_2Pd) has been synthesized by the reaction of 4-chloro-2-[(6-methylpyridin- 2-ylimino)-methyl]-phenol with Pd(CH_3COO)_2, and characterized by IR spectrum and elemental analysis. Single-crystal X-ray diffraction analysis results further confirmed the molecular structures. The crystal belongs to the monoclinic system, space group P2_1/c with a = 4.1324(2), b = 23.5432(16), c = 11.8943(8) A, β = 91.238(5)o, V = 1156.93(12) ?~3, C_(26)H_(20)Cl_2N_4O_2Pd, M_r = 597.76, Z = 2, D_c = 1.716 g/cm^3, μ = 1.067 mm^(-1), F(000) = 600, the final R = 0.0247 and w R = 0.0677(I 〉 2σ(I)). In the presence of methylaluminoxane(MAO), the complex exhibits excellent catalytic activities(1.737×10~7 g of PNB(mol of Pd)^(-1)·h^(-1)) in the vinyl polymerization of norbornene.展开更多
Two novel copper complexes with methyl or trifluoro-substituted mono-β-diiminato ligands and one acetoxyl anion were synthesized and characterized by IR spectroscopy and elemental analysis for the first time. The str...Two novel copper complexes with methyl or trifluoro-substituted mono-β-diiminato ligands and one acetoxyl anion were synthesized and characterized by IR spectroscopy and elemental analysis for the first time. The structure of complex 2 bearing trifluoro substituents was further confirmed by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1 with a = 7.377(4), b = 11.727(6), c = 12.913(7) ?, α = 116.569(6), β = 98.829(7), γ = 96.520(6)°, V = 966.2(8) ?3, Z = 2, Mr = 479.86, Dc = 1.649 g/cm3, F(000) = 482, μ = 1.205 mm-1, the final R = 0.0370 and w R = 0.0903 for 3430 observed reflections with I 〉 2σ(I). These mono-β-diiminato copper complexes can effectively catalyze methacrylate(MA) polymerization when activated by MMAO. The introduction of fluoro groups into the N-aryl ring of β-diiminato ligands can greatly increase the catalytic activity of copper complexes as well as the molecular weight of PMA.展开更多
A novel zinc complex [Zn(BIB)(bdc)]n(1, BIB = 1,3-bis(imidazol-1-yl)benzene, bdc = 1,3-benzenedicarboxylate) has been synthesized in solvothermal conditions. The title complex was characterized by elemental an...A novel zinc complex [Zn(BIB)(bdc)]n(1, BIB = 1,3-bis(imidazol-1-yl)benzene, bdc = 1,3-benzenedicarboxylate) has been synthesized in solvothermal conditions. The title complex was characterized by elemental analysis, IR spectra, thermal analysis, single-crystal and powder X-ray diffraction. The result proved that the alliance of BIB and aromatic carboxylic acids is good for the diversity of getatable structure. Complex 1 crystallizes in the monoclinic system of P2/c space group with a = 11.5591(10), b = 9.6239(8), c = 33.727(3)A, β = 103.816(3)°, V = 3643.4(5) A^3, Z = 8, μ = 1.385 mm^-1, F(000) = 1792, Dc = 1.603 g/cm^3 and Mr = 439.72 g/mol. Additionally, luminescent properties of complex 1 are also investigated and it shows good fluorescence.展开更多
文摘Consider the real, simply-connected, connected, s-step nilpotent Lie group G endowed with a left-invariant, integrable almost complex structure J, which is nilpotent. Consider the simply-connected, connected nilpotent Lie group Gk, defined by the nilpotent Lie algebra g/ak, where g is the Lie algebra of G, and ak is an ideal of g. Then, J gives rise to an almost complex structure Jk on Gk. The main conclusion obtained is as follows: if the almost complex structure J of a nilpotent Lie group G is nilpotent, then J can give rise to a left-invariant integrable almost complex structure Jk on the nilpotent Lie group Gk, and Jk is also nilpotent.
基金the National Natural Science Foundation of China (41674131,41574118,41974146,41904109)the Fundamental Research Funds for the Central Universities (17CX06041,17CX06044)the China National Science and Technology Major Project (2016ZX05007-004,2017ZX05072-002)
文摘Electromagnetic logging while drilling(LWD)is one of the key technologies of the geosteering and formation evaluation for high-angle and horizontal wells.In this paper,we solve the dipole source-generated magnetic/electric fields in 2D formations efficiently by the 2.5D finite diff erence method.Particularly,by leveraging the field’s rapid attenuation in spectral domain,we propose truncated Gauss–Hermite quadrature,which is several tens of times faster than traditional inverse fast Fourier transform.By applying the algorithm to the LWD modeling under complex formations,e.g.,folds,fault and sandstone pinch-outs,we analyze the feasibility of the dimension reduction from 2D to 1D.For the formations with smooth lateral changes,like folds,the simplified 1D model’s results agree well with the true responses,which indicate that the 1D simplification with sliding window is feasible.However,for the formation structures with drastic rock properties changes and sharp boundaries,for instance,faults and sandstone pinch-outs,the simplified 1D model will lead to large errors and,therefore,2.5D algorithms should be applied to ensure the accuracy.
基金the Advisory Group on Inter-national Agricultural Research(BEAF)at the German Agency for International Cooperation(GIZ)within the German Ministry for Economic Cooperation(BMZ)for funding this research(project number 08.7860.3-001.00“Making the Mekong Con-nected”-MMC).
文摘The horizontal distribution of stems, stand density and the differentiation of tree dimensions are among the most important aspects of stand structure. An increasing complexity of stand structure is often linked to a higher number of species and to greater ecological stability. For quantification, the Structural Complexity Index (SCI) describes structural complexity by means of an area ratio of the surface that is generated by connecting the tree tops of neighbouring trees to form triangles to the surface that is covered by all triangles if projected on a flat plane. Here, we propose two ecologically relevant modifications of the SCI: The degree of mingling of tree attributes, quantified by a vector ruggedness measure, and a stem density term. We investigate how these two modifications influence index values. Data come from forest inventory field plots sampled along a disturbance gradient from heavily disturbed shrub land, through secondary regrowth to mature montane rainforest stands in Mengsong, Xishuangbanna,Yunnan,China. An application is described linking structural complexity, as described by the SCI and its modified versions, to changes in species composition of insect communities. The results of this study show that the Enhanced Structural Complexity Index (ESCI) can serve as a valuable tool for forest managers and ecologists for describing the structural complexity of forest stands and is particularly valuable for natural forests with a high degree of structural complexity.
基金The authors would like to acknowledge the National Natural Science Fund Project(62173049)for Key Projectthe Open Fund Project“Study on Transient Flow Mechanism of Fluid Accumulation in Shale Gas Wells”of the Sinopec Key Laboratory of Shale Oil/Gas Exploration and Production Technology.
文摘At present,the optimization of the plunger mechanism is shale gas wells is mostly based on empirical methods,which lack a relevant rationale and often are not able to deal with the quick variations experienced by the production parameters of shale gas wells in comparison to conventional gas wells.In order to mitigate this issue,in the present work,a model is proposed to loosely couple the dynamics of gas inflow into shale gas wells with the dynamics of the liquid inflow.Starting from the flow law that accounts for the four stages of movement of the plunger,a dynamic model of the plunger lift based on the real wellbore trajectory is introduced.The model is then tested against 5 example wells,and it is shown that the accuracy level is higher than 90%.The well‘switch’,optimized on the basis of simulations based on such a model,is tested through on-site experiments.It is shown that,compared with the original switch configuration,the average production of the sample well can be increased by about 15%.
基金The Construction S&T Project of the Department of Transportation of Sichuan Province(Grant No.2023A02)the National Natural Science Foundation of China(No.52109135).
文摘The surrounding geological conditions and supporting structures of underground engineering are often updated during construction,and these updates require repeated numerical modeling.To improve the numerical modeling efficiency of underground engineering,a modularized and parametric modeling cloud server is developed by using Python codes.The basic framework of the cloud server is as follows:input the modeling parameters into the web platform,implement Rhino software and FLAC3D software to model and run simulations in the cloud server,and return the simulation results to the web platform.The modeling program can automatically generate instructions that can run the modeling process in Rhino based on the input modeling parameters.The main modules of the modeling program include modeling the 3D geological structures,the underground engineering structures,and the supporting structures as well as meshing the geometric models.In particular,various cross-sections of underground caverns are crafted as parametricmodules in themodeling program.Themodularized and parametric modeling program is used for a finite element simulation of the underground powerhouse of the Shuangjiangkou Hydropower Station.This complicatedmodel is rapidly generated for the simulation,and the simulation results are reasonable.Thus,this modularized and parametric modeling program is applicable for three-dimensional finite element simulations and analyses.
基金Mengxi Wang holds a doctoral scholarship from the China scholarship council(CSC:202003270025)。
文摘Vertical forest structure is closely linked to multiple ecosystem characteristics,such as biodiversity,habitat,and productivity.Mixing tree species in planted forests has the potential to create diverse vertical forest structures due to the different physiological and morphological traits of the composing tree species.However,the relative importance of species richness,species identity and species interactions for the variation in vertical forest structure remains unclear,mainly because traditional forest inventories do not observe vertical stand structure in detail.Terrestrial laser scanning(TLS),however,allows to study vertical forest structure in an unprecedented way.Therefore,we used TLS single scan data from 126 plots across three experimental planted forests of a largescale tree diversity experiment in Belgium to study the drivers of vertical forest structure.These plots were 9–11years old young pure and mixed forests,characterized by four levels of tree species richness ranging from monocultures to four-species mixtures,across twenty composition levels.We generated vertical plant profiles from the TLS data and derived six stand structural variables.Linear mixed models were used to test the effect of species richness on structural variables.Employing a hierarchical diversity interaction modelling framework,we further assessed species identity effect and various species interaction effects on the six stand structural variables.Our results showed that species richness did not significantly influence most of the stand structure variables,except for canopy height and foliage height diversity.Species identity on the other hand exhibited a significant impact on vertical forest structure across all sites.Species interaction effects were observed to be site-dependent due to varying site conditions and species pools,and rapidly growing tree species tend to dominate these interactions.Overall,our results highlighted the importance of considering both species identity and interaction effects in choosing suitable species combinations for forest management practices aimed at enhancing vertical forest structure.
基金Supported by National Natural Science Foundation of China(Grant No.12171140).
文摘In this paper,we revisit the Kahler structures on the affine quadrics M1={z_(1)^(2)+z_(2)^(2)+z_(3)^(2)=1}in the paper by Bo Yang and Fang-Yang Zheng.We found that the Kahler structures on the complex surface are more complicated than what they have thought.We shall also give some detail calculations and found that our results fit quite well with earlier papers of the first author,one of them with X.X.Chen.
文摘In this paper, the X-ray nondestructive test method of small defects in precision weldments with complex structure was presented. To resolve the difficulty of defect segmentation in variable grey image, the image processing based on Visual Basic programming method was adopted. The methods of automatic contrast and partial grey stretch were used to enhance the X-ray detection image which has relatively low contrast, then automatic threshold method was carried out to segment the two high intensity zones, and weld zones which contain the small defects was extracted. Smoothing and sharpen processing were proceeded on the extracted weld zones, and small defects in X-ray detection image of weldments with complex structure were segmented by using the method of background subtraction in the end. The effects of raster were eliminated, and because of that the image processing was only proceeded on the extracted weld zones, the calculated speed using the above provided algorithm was improved.
文摘Inclusion compound of retinoic acid with (-cyclodextrin was prepared by coprecipitating method, the structure of resulting product was studied by elemental analysis, differential scanning caloriemetry(DSC) analysis, FT-IR spectroscopy and X-ray diffractometry, and the formed supramolecule self-assembles in aqueous solution according to molar ratio 2:1 of host-guest.
基金Supported by the NNSFC(21301087)Programs of Higher-level talents of Inner Mongolia University(SPH-IMU-30105-125135)Inner Mongolia autonomous region natural science fund project(2013MS0206)
文摘One complex with a zwitterionic dicarboxylate ligand, [Mn(L)(N3)]n 1 (L = 1-car- boxymethylpyridinium-3-carboxylate), was synthesized and structurally characterized. Complex 1 crystallizes in triclinic, space group P1 with a = 7.570(2), b = 7.808(2), c = 9.232(3) A, β= 94.450(19)°, V= 489.0(3) A3, Z = 2, Mr = 277.11, Dc = 1.882 g/cm3, F(000) = 278,μ = 1.359 mm-1, S = 1.021, the final R = 0.0509 and wR = 0.1149 for 2236 observed reflections with 1 〉 2σ(I). Complex 1 consists of two-dimensional coordination layers in which the anionic uniform chains with mixed triple bridges (one end-on (EO) azide and two syn-syn carboxylates) are cross-linked by the flexible cationic N-methylpyridinium spacers. Magnetic studies demonstrated that the triple bridge in 1 transmits antiferromagnetic coupling between the Mn(Ⅱ) ions.
基金The project is partially supported by the NSFC(11871282,11931007)BNSF(Z190003)Nankai Zhide Foundation.
文摘The main purpose of this note is to construct almost complex or complex structures on certain isoparametric hypersurfaces in unit spheres.As a consequence,complex structures on S^(1)×S^(7)×S^(6),and on S^(10)×S^(3)×S(2)with vanishing first Chern class,are built.
基金supported by the Open Project of Key Laboratory of Prevention and Treatment of Cardiovascular and Cerebrovascular Diseases,Ministry of Education(No.XN201904)Gannan Medical University(No.QD201910)+1 种基金the National Natural Science Foundation of China(Nos.31770795 and 31971043)the Jiangxi Province Natural Science Foundation(No.20181ACB20014)
文摘Heat shock proteins(Hsps)are a family of abundantly expressed ATP-dependent chaperone proteins.Hsp90 is an eminent member of Hsp family.Thus far,two primary functions have been described for Hsp90:first,as a regulator of conformational change of some protein kinases and nuclear hormone receptors,and the other as an indispensable factor in cellular stress response.Hsp90 has an essential number of interaction proteins since it participates in almost every biological process and its importance is self-evident.Hsp90 has an inextricable relationship in the pathogenesis of cancer,especially in the proliferation and irradiation of cancer cells,thus being a notable cancer target.Since the discovery of geldanamycin,the first inhibitor of Hsp90,from the bacterial species Streptomyces hygroscopicus,even more attention has been focused toward Hsp90.Many structure-based inhibitors of Hsp90 have been designed to develop an innovative method to defeat cancer.However,already designed inhibitors have various deficiencies,such as hepatotoxicity,poor aqueous solubility,instability,and non-ideal oral bioavailability.Based on the aforementioned reasons and to achieve an optimal performance and fewer side effects,we designed a novel inhibitor of Hsp90,called FS5,and resolved the crystal structure of the Hsp90^N-FS5 complex(1.65 A°,PDB code 5XRB).Furthermore,we compared the complexes Hsp90^N,Hsp90^N-GDM,and Hsp90^N-ATP and suggest that the inhibitor FS5 may compete with ATP for binding to Hsp90,which can be regarded as a potential strategy for the development of novel cancer drugs in the future.
基金Project supported by the Fundamental Research Funds for the Central Universities (Grant No. YWF-10-02-040)
文摘Using a tight binding transfer matrix method, we calculate the complex band structure of armchair graphene nanoribbons. The real part of the complex band structure calculated by the transfer matrix method fits well with the bulk band structure calculated by a Hermitian matrix. The complex band structure gives extra information on carrier's decay behaviour. The imaginary loop connects the conduction and valence band, and can profoundly affect the characteristics of nanoscale electronic device made with graphene nanoribbons. In this work, the complex band structure calculation includes not only the first nearest neighbour interaction, but also the effects of edge bond relaxation and the third nearest neighbour interaction. The band gap is classified into three classes. Due to the edge bond relaxation and the third nearest neighbour interaction term, it opens a band gap for N = 3M- 1. The band gap is almost unchanged for N =3M + 1, but decreased for N = 3M. The maximum imaginary wave vector length provides additional information about the electrical characteristics of graphene nanoribbons, and is also classified into three classes.
基金supported by the National Natural Science Foundation of China(No.20801012)New Energy Technology Co.Ltd.of Ai Naji of Jiangsu Province(No.8507040091)
文摘The crystal structure of one novel Mn(II) complex, [Mn(pmta)_3]_2[Mn(H_2O)_6]·4H_2O(1), is reported(Hpmta = 5-methyl-1-phenyl-1H-1,2,3-triazole-4-carboxylic acid). In the title compound, the asymmetric unit consists of a [Mn(pmta_)3]ˉ anion, half [Mn(H_2O)_6]^(2+) counter cation and two lattice H_2O molecules, and the intra- and intermolecular hydrogen bonds connect the complex into a supramolecular structure. The liquid-state fluorescence spectra of complex 1 have been determined. Hirshfeld surface analysis was also studied. The main intermolecular interactions in the complex are O···H and H···H contacts.
基金Supported by the National Natural Science Foundation of China(No.21061003)
文摘The two complexes [HgI_2L](DMF)(1) and [AgL_2](ClO_4)(CH_3CN)(2) were synthesized from the reaction of Schiff base ligand(2-acetylpyridine-p-aminobenzoylhydrazone)(L) with HgI_2 or AgClO_4 respectively. The compounds are characterized by ^1H NMR,FTIR and elemental analysis. The structures of the ligand and two complexes are measured via single-crystal X-ray diffraction. In these two complexes,the structures are both distorted triangular bipyramids with five-coordinated centers.
基金Supported by the NNSFC(No.21373223)Chunmiao project of Haixi Institute of Chinese Academy of Sciences(CMZX-2014-001)
文摘With transition metal complex, a discrete cuprous iodide compound, namely, [Ni(phen)3]2Cu6I10(1, phen = 1,10-phenanthroline) has been solvothermally synthesized and structurally characterized. Single-crystal X-ray diffraction studies revealed that compound 1 crystallizes in triclinic space group P1(No. 2) with a = 11.2694(2), b = 12.3699(3), c = 15.0387(3) ?, α = 102.840(2), β = 105.215(2), γ = 96.388(2)°, V = 1940.04(7) ^3, Z = 1, Dc = 2.438 g·cm^-3, F(000) = 1324, R = 0.0256 and w R = 0.0555(I 〉 2σ(I)). Compound 1 features a discrete anionic moiety of [Cu6I10]^4- charge-balanced by two metal complexes of [Ni(phen)3]2+. The optical absorption edge of compound 1 was estimated to be 2.24 eV. Interestingly, nearly 95% of contaminant(crystal violet aqueous solution(CV), 50 m L, 1.0 × 10^-5 M) could be decolorized after exposure to visible light within 30 min, illustrating an impressive photocatalytic activity of compound 1. The thermal stability of 1 has also been studied.
基金Supported by the Natural Science Foundation of Zhejiang Province (Y12B010003)
文摘A new structure with the molecular formula [CdL]n was formed by CdSO4 with 4-carboxymethoxy phenylacetic acid (H2L) through the hydrothermal method. The complex was characterized by elemental analysis and infrared spectroscopy. The structure of the complex was determined by single-crystal X-ray diffraction, which is of monoclinic system, space group P21/c with a = 10.3887(2), b = 7.10710(10), c = 14.7212(2) , β = 120.6940(10)°, V = 934.65(3) 3, Dc = 2.278 g·cm-3, Z = 4, F(000) = 624, S = 1.022, the final R = 0.0187 and wR = 0.0487 for 2000 observer reflections (Ⅰ 〉 2σ(Ⅰ)). The center metal ion Cd(Ⅱ) in the complex is six-coordinated in a distorted octahedral geometry, and is connected with L ligands to form a 3D fishing net structure, which is a novel (3,6) network topology. The luminescence of the complex has been investigated, and the result reveals that it displays luminescent property in the voilet region.
基金Supported by the Ministry of Education of China(No.208066)the Education Department of Fujian Province(JA07029)the State Key Laboratory of Structural Chemistry(No.20130013)
文摘The title complex bis{4-chloro-2-[(6-methyl-pyridin-2-ylimino)-methyl]-phenol}-palladium(Ⅱ)(C_(26)H_(20)Cl_2N_4O_2Pd) has been synthesized by the reaction of 4-chloro-2-[(6-methylpyridin- 2-ylimino)-methyl]-phenol with Pd(CH_3COO)_2, and characterized by IR spectrum and elemental analysis. Single-crystal X-ray diffraction analysis results further confirmed the molecular structures. The crystal belongs to the monoclinic system, space group P2_1/c with a = 4.1324(2), b = 23.5432(16), c = 11.8943(8) A, β = 91.238(5)o, V = 1156.93(12) ?~3, C_(26)H_(20)Cl_2N_4O_2Pd, M_r = 597.76, Z = 2, D_c = 1.716 g/cm^3, μ = 1.067 mm^(-1), F(000) = 600, the final R = 0.0247 and w R = 0.0677(I 〉 2σ(I)). In the presence of methylaluminoxane(MAO), the complex exhibits excellent catalytic activities(1.737×10~7 g of PNB(mol of Pd)^(-1)·h^(-1)) in the vinyl polymerization of norbornene.
基金Supported by the National Natural Science Foundation of China(21172269)the Applied Fundamental Research Project of Wuhan City(2015011701011598)
文摘Two novel copper complexes with methyl or trifluoro-substituted mono-β-diiminato ligands and one acetoxyl anion were synthesized and characterized by IR spectroscopy and elemental analysis for the first time. The structure of complex 2 bearing trifluoro substituents was further confirmed by single-crystal X-ray diffraction. The crystal belongs to the triclinic system, space group P1 with a = 7.377(4), b = 11.727(6), c = 12.913(7) ?, α = 116.569(6), β = 98.829(7), γ = 96.520(6)°, V = 966.2(8) ?3, Z = 2, Mr = 479.86, Dc = 1.649 g/cm3, F(000) = 482, μ = 1.205 mm-1, the final R = 0.0370 and w R = 0.0903 for 3430 observed reflections with I 〉 2σ(I). These mono-β-diiminato copper complexes can effectively catalyze methacrylate(MA) polymerization when activated by MMAO. The introduction of fluoro groups into the N-aryl ring of β-diiminato ligands can greatly increase the catalytic activity of copper complexes as well as the molecular weight of PMA.
基金supported by grants from Provincial Key Projects of Anhui Natural Science Research in Universities(No.KJ2015A203)the Natural Science Foundation of Anhui Province(No.1408085MB40)Projects of Anhui Key Laboratory of Spin Electron and Nanomaterials,Suzhou University(No.2014YKF51)
文摘A novel zinc complex [Zn(BIB)(bdc)]n(1, BIB = 1,3-bis(imidazol-1-yl)benzene, bdc = 1,3-benzenedicarboxylate) has been synthesized in solvothermal conditions. The title complex was characterized by elemental analysis, IR spectra, thermal analysis, single-crystal and powder X-ray diffraction. The result proved that the alliance of BIB and aromatic carboxylic acids is good for the diversity of getatable structure. Complex 1 crystallizes in the monoclinic system of P2/c space group with a = 11.5591(10), b = 9.6239(8), c = 33.727(3)A, β = 103.816(3)°, V = 3643.4(5) A^3, Z = 8, μ = 1.385 mm^-1, F(000) = 1792, Dc = 1.603 g/cm^3 and Mr = 439.72 g/mol. Additionally, luminescent properties of complex 1 are also investigated and it shows good fluorescence.