Research on Simulation Methods of Electric Field Intensity on Surface of 10 kV Cable Joint

The electric field intensity (EFI) is important characteristic quantity for evaluating the internal insulation state of cable joints. Based on finite element method, this paper proposes two EFI research methods, field-circuit coupling method and equivalent circuit method. The average EFI of the inner surface of the outer semi-conducting shield can be calculated from the current in the measuring circuit. The relative error between these two methods is about 15%, which roughly proves the consistency of the two methods. Further practical application research enables online monitoring of cable joints.

Inherent Properties of Two Dimension Green Function with Linear Boundary Condition of Free Water Surface

A mathematic model of Green function is build for two dimension free water surface. The analytic expression of Green function is obtained by introducing a parameter of complex number. The intrinsic properties of Green function are discussed for the special parameter values. The real and imaginary parts of H function are shown in the paper.

Nonlinear Switching Transient Field Simulation of Cable Joint without Residual Charge

The analysis of the impulse voltage on the internal electric field of the cable joint plays a key role in studying the breakdown of the joint. Based on the finite element method, a three-dimensional electromagnetic field simulation model of the cable joint is established in this paper. Simulation results show that the voltage at the head of the cable joint reaches about twice the impulse voltage. The increase of the conductivity of semi-conductive material also leads to the increase of electric field intensity. Then, several points and curves at different positions are selected for further analysis in this paper. Among them, the electric field distortion at the edge of the high voltage shield is the most serious and the electric field in the air gap is the least.

3D metal-organic frameworks based on lanthanide-seamed dimeric pyrogallol[4]arene nanocapsules

Two novel 3D metal-organic frameworks(MOFs)with cds network,{[Me NH_3]_7[Ln_8(Pg C_2)_2(H_2O)_y(HCOO)_7]}_n·x(Solvent)(FJI-Y4,FJI=Fujian Institute,Ln=Gd,y=12;FJI-Y5,Ln=Dy,y=11;Pg C_2=C-ethylpyrogallol[4]arene),based on unprecedented dimeric pyrogallol[4]arene-based Ln_8metal-organic nanocapsule(MONC)supramolecular building blocks and formate linkers,have been prepared under solvothermal conditions.To our best of knowledge,they present not only the first two examples of 3D hierarchical structures constructed from MONCs in metal-pyrogallol[4]arene system,but also the first two examples of MOFs based on lanthanide MONCs.Remarkably,the inner cavity volume of the Ln_8capsule in FJI-Y4 and FJI-Y5 is approximately151?~3,which is larger than those found in previous transition metal-seamed dimeric Pg C_n-based MONCs.Magnetic investigation on FJI-Y4 suggests a significant magnetocaloric effect(23.97 J kg^(-1)K^(-1),ΔH=7 T,2.5 K),while FJI-Y5 exhibits slow relaxation of the magnetization.

Modeling of acute cadmium toxicity in solution to barley root elongation using biotic ligand model theory

Protons（H^＋）as well as different major and trace elements may inhibit cadmium（Cd）uptake in aquatic organisms and thus alleviate Cd toxicity.However,little is known about such interactions in soil organisms.In this study,the independent effects of the cations calcium（Ca^2＋）,magnesium（Mg^2＋）,potassium（K^＋）,H^＋ and zinc（Zn^2＋）on Cd toxicity were investigated with 5-day long barley root elongation tests in nutrient solutions.The tested concentrations of selected cations and trace metal ions were based on the ranges that occur naturally in soil pore water.The toxicity of Cd decreased with increasing activity of Ca^2＋,Mg^2＋,H^＋and Zn^2＋,but not K^＋.Accordingly,conditional binding constants were obtained for the binding of Cd^2＋,Ca^2＋,Mg^2＋,H^＋,and Zn^2＋ with the binding ligand：log K（CdBL）5.19,logK（CaBL）2.87,logK（MgBL）2.98,logK（HBL）5.13 and logK（ZnBL）5.42,respectively.Furthermore,it was calculated that on average 29% of the biotic ligand sites needed to be occupied by Cd to induce a 50% decrease in root elongation.Using the estimated constants,a biotic ligand model was successfully developed to predict the Cd toxicity to barley root elongation as a function of solution characteristics.The feasibility and accuracy of its application for predicting Cd toxicity in soils were discussed.

An ultra-stable microporous supramolecular framework with highly selective adsorption and separation of water over ethanol

A microporous supramolecular framework with high water and thermal stability can selectively absorb water molecules over methanol or ethanol due to the suitable channels.The model separation test on columns shows that an ultra-pure ethanol(99.9%)can be obtained from the mixture of ethanol/water(95:5).Additionally,after refluxing the desolvated sample in 95%ethanol at 60℃for 5 h,the purity of ethanol rises up to 97.43%,which is obviously higher than 96.56%for 4 A molecular sieves.

An Ultrastable π-π Stacked Porous Organic Molecular Framework as a Crystalline Sponge for Rapid Molecular Structure Determination

The crystalline sponge method is a pragmatic and promising strategy for molecular structure determination.However,the dominant metal-organic framework crystal sponge platforms always face poor chemical stability,especially solvent instability,hampering their application in a vaster domain.Herein,we report an ultrastable π-π stacked porous organic molecular framework which exhibits permanent porosity,high thermal stability,and good chemical resistance.It can efficiently implement an approach to molecular structure determination via a single-crystal-to-single-crystal transformation.This is the first example utilizing π-π stacked porous organic molecular framework as“crystalline sponge”to determine a wide variety of guests,ranging from hydrophilic to hydrophobic,and from aliphatic to aromatic,which complements the crystalline sponges based on the famous metal-organic frameworks.More importantly,it can achieve rapid structure determination of small molecules within 3 h.

Tuning the Structure of Fe-Tetracarboxylate Frameworks Through Linker-Symmetry Reduction

The design and synthesis of stable metal–organic frameworks(MOFs)have been a core obstacle in the widespread application of these functional crystalline porous materials,because of the stability limitations of MOFs under harsh operating conditions.Herein,a highly stable microporous MOF based on the Fe_(3)O cluster(PCN-678)has been synthesized using a tetracarboxylate ligand.Utilizing symmetry reduced tetratopic carboxylate ligand,a mesoporous MOF(PCN-668)could be obtained in which nanoscale cage-like building units and one-dimensional(1D)channels coexist.The neighboring cages were mutual diastereomers in PCN-668 due to the further reduction of the Cs symmetry of the free ligand to C1 symmetry after self-assembly.Furthermore,the acid stability of this mesoporous MOF was improved via postsynthetic metal exchange to chromium(PCN-668-Cr).The PCN-668-Cr exhibited very high stability in both acidic and basic aqueous solutions(pH=1–11).Additionally,the mesoporous MOF showed a high total gravimetric methane uptake(∼500 cm^(3) g^(−1) at 100 bar),while the microporous MOF showed a high volumetric methane storage capacity of 147 cm3 cm−3 at room temperature.

Successive magnetic ordering in two Co^(Ⅱ)-ladder metal-organic frameworks

Metal-organic frameworks showing successive magnetic ordering are far less common than inorganic compounds.Here,we report two metal-organic frameworks[Co^Ⅱ(ox)(bphy)·0.1(DMF)·0.1(Me OH)]n(1)and[Co3^Ⅱ(ox)3(bphy)2(DMF)2]n(2)comprised of zigzag and necklace Co^Ⅱ-ladders,respectively.Together with a previously reported compound[Co^Ⅱ(ox)(bphy)·0.2(DMF)]n(3)consisting of spiraling zigzag Co^Ⅱ-ladders,these three compounds provide a good system for comparative structural and magnetic studies.Comprehensive magnetic analysis reveals that the three compounds undergo long-range magnetic ordering at^2.6 K but exhibit vastly different short-range magnetic correlations:compound 1 shows short-range spin-canted antiferromagnetism ordering at^14.0 K;compound 2 demonstrates successive short-range antiferromagnetism ordering at^15.5and^12.6 K;compound 3 shows slow magnetic relaxation with Tb≈4.6 K.These results demonstrate long-range magnetic ordering is readily accessible in the frameworks of ox^2-bridging Co^Ⅱ-ladders linked by bphy,where short-range magnetic correlations can be systematicly tuned by the Co^Ⅱ-ladder structures.