Sound Transmission Loss Analysis of a Double Plate-Acoustic Cavity Coupling System with In-Plane Functionally Graded Materials

In this paper, the isogeometric analysis (IGA) is employed to develop an acoustic radiation model for a double plate-acoustic cavity coupling system, with a focus on analyzing the sound transmission loss (STL). The functionally graded (FG) plate exhibits a different material properties in-plane, and the power-law rule is adopted as the governing principle for material mixing. To validate the harmonic response and demonstrate the accuracy and convergence of the isogeometric modeling, ANASYS is utilized to compare with numerical examples. A plane wave serves as the acoustic excitation, and the Rayleigh integral is applied to discretize the radiated plate. The STL results are compared with the literature, confirming the reliability of the coupling system. Finally, the investigation is conducted to study impact of cavity depth and power-law parameter on the STL.

Synthesis and Structural Characterization of a New Cadmium(II) Complex with a Double Betaine

A new flexible double betaine L （L = 1,4-bis（pyridinio-4-carboxylato-N-methyl）benzene, C20H16N2O4） and its cadmium（Ⅱ） complex [Cd（H2O）aL（NO3）]NO3.H2O 1 were synthesized. Complex 1 was obtained by self-assembly reaction of [Cd（NO3）2]-4H2O and L in hot water,and its crystal structure was determined by single-crystal X-ray diffraction analysis. Crystallographic data for complex 1： C20H24CdN4O14.H2O, Mr = 674.85, monoclinic, space group P21/c, a =13.7854（3）, b = 14.2820（3）, c = 14.9188（4） ,A°, β = 116.418（1）°, V = 2630.5（1）A°^3, Z = 4, Dc= 1.704g/cm^3,/J（MoKα） = 0.911 mm^-1, F（000） = 1368, the final R = 0.0315 and wR = 0.0768 for 3637 observed reflections with I 〉 2σ（I）. In complex 1, L acts as a monodentate ligand to link a Cd（Ⅱ） ion in a novel coordination mode of double betaines. The mononuclear [Cd（H2O）aL（NO3）] units are connected through intermolecular hydrogen bonds and π-π stacking reactions to generate a 3D network.

Investigation on structural component behaviours of double bottom arrangement under grounding accidents

Marine accidents have caused immense casualties on various parties in shipping and shipbuilding industries, including financial and structural losses. This situation makes ship accident becomes a critical subject in naval architecture and marine structures, as it needs continuous assessment and investigation to broaden insight and data of collision and grounding phenomena. The paper aims to investigate structural conditions of a ship arranged by double hull system under accidental scenario, namely ship grounding. Fundamental concept of structure-rock interaction in poweredhard grounding is adopted to design impact configuration for calculation using finite element(FE)simulation. Involved entities are defined as the structure represented by tanker vessel, and oceanic rock is deployed as the indenter in analysis. Calculation results indicate that the crashworthiness capability of structural part strengthened by longitudinal girder is higher than other selected locations on the structures against rock penetration. Localized flooding of storage oil may occur during raking damage is formed on structural part between two girders.

A STUDY ON THE STRUCTURAL EFFECT OF DOUBLE BRIDGES CONJUGATED SYSTEMS I.CARBONYL-IMINO SYSTEM

The struetural effect of the conjugative system(C)with carbonyl-imino bridges has been studied.The results show that:In the conjugated system(C),there is no electronic absorption peak attributable to the whole system,but there are three π-π* bands each nt which displays chacactecistics of its own independently.These indicate that the two bridges-carbonyl-and-imino-can block the tlanSmlSSion of the conjngative polarization of the whole system,so as to form three segments,this is verified by means of chemical synthesis and degradation.

Structure Design Considerations of a Sub-50nm Self-Aligned Double-Gate MOSFET

A comprehensive way to design a sub 50nm SADG MOSFET with the ability of being fabricated by improved CMOS technique is described.Under this way,the gate length and thickness of Si island of DG device show many different scaling limits for various elements.Meanwhile,the spacer insulator shows a kind of width thickness on device drain current and circuit speed.A model about that effect is developed and offers design consideration for future.A new design of channel doping profile,called SCD,is also discussed here in detail.The DG device with SCD can achieve a good balance between the volume inversion operation mode and the control of V th .Finally,a guideline to make a SADG MOSFET is presented.

Layered double hydroxides as electrode materials for flexible energy storage devices

To prevent and mitigate environmental degradation,high-performance and cost-effective electrochemical flexible energy storage systems need to be urgently developed.This demand has led to an increase in research on electrode materials for high-capacity flexible supercapacitors and secondary batteries,which have greatly aided the development of contemporary digital communications and electric vehicles.The use of layered double hydroxides(LDHs)as electrode materials has shown productive results over the last decade,owing to their easy production,versatile composition,low cost,and excellent physicochemical features.This review highlights the distinctive 2D sheet-like structures and electrochemical characteristics of LDH materials,as well as current developments in their fabrication strategies for expanding the application scope of LDHs as electrode materials for flexible supercapacitors and alkali metal(Li,Na,K)ion batteries.

PRICING EUROPEAN OPTION IN A DOUBLE EXPONENTIAL JUMP-DIFFUSION MODEL WITH TWO MARKET STRUCTURE RISKS AND ITS COMPARISONS

Using Fourier inversion transform, P.D.E. and Feynman-Kac formula, the closedform solution for price on European call option is given in a double exponential jump-diffusion model with two different market structure risks that there exist CIR stochastic volatility of stock return and Vasicek or CIR stochastic interest rate in the market. In the end, the result of the model in the paper is compared with those in other models, including BS model with numerical experiment. These results show that the double exponential jump-diffusion model with CIR-market structure risks is suitable for modelling the real-market changes and very useful.

Numerical simulation and control of welding distortion for double floor structure of high speed train

The welding heat source models and the plastic tension zone sizes of a typical weld joint involved in the double floor structure of high speed train under different welding parameters were calculated by a thermal-elastic-plastic FEM analysis based on SYSWELD code.Then,the welding distortion of floor structure was predicted using a linear elastic FEM and shrinkage method based on Weld Planner software.The effects of welding sequence,clamping configuration and reverse deformation on welding distortion of floor structure were examined numerically.The results indicate that the established elastic FEM model for floor structure is reliable for predicting the distribution of welding distortion in view of the good agreement between the calculated results and the measured distortion for real double floor structure.Compared with the welding sequence,the clamping configuration and the reverse deformation have a significant influence on the welding distortion of floor structure.In the case of30 mm reverse deformation,the maximum deformation can be reduced about 70%in comparison to an actual welding process.

The tuning of pore structures and acidity for Zn/Al layered double hydroxides:The application on selective hydrodesulfurization for FCC gasoline

Co–Mo catalysts applied on the hydrodesulfurization（HDS） for FCC gasoline were prepared with Zn–Al layered double hydroxides（LDHs） to improve their performances,and the effects of pore structures and acidity on HDS performances were studied in detail. A series of Zn–Al/LDHs samples with different pore structures and acidities are synthesized on the bases of co-precipitation of OH-,CO2-,Al3＋,and Zn2＋. The neutralization p H is a main factor to affect the pore structures and acidity of Zn–Al/LDHs,and a series of Zn–Al/LDHs with different pore structures and acidities are obtained. Based on the representative samples with different specific surface areas（SBET） and acidities,three Co Mo/LDHs catalysts were prepared,and their HDS performances were compared with traditional Co Mo/Al2O3 catalysts. The results indicated that catalysts prepared with high SBETpossessed high HDS activity,and Br？nsted acid sites could reduce the thiol content in the product to some extent. All the three catalysts prepared with LDHs displayed little lower HDS activity but higher selectivity than Co Mo/Al2O3,and could restrain the reactions of re-combination between olefin and H2 S which could be due to the existence of Br？nsted acid sites.

Design and test of a protective structure for the double vertical explosive welding of large titanium/steel plate

A comprehensive protective structure with rigidity and flexibility was put forward and designed in view of the quality and safety problems for the double vertical explosive welding of large titanium/steel cladding plate.The movement speed and displacement of the protective structure was calculated by establishing its physics model.The dynamics and stabilization properties were analyzed,and the protective structure parameters were optimized and devised.The comprehensive protective structure,which is composed of rigidity unit and flexibility wall,can bear the impact of detonation wave and the high-speed movement of the cladding plate.There are no damage and deformation in the protective structure and the cladding plate.The protective structure can be used many times.The bonding rate of the Ti/steel plate obtained was nearly 100%,and there is no deformation,surface cracks,and big wave and micro-defects.Therefore,the protective problems of the double vertical explosive welding can be solved effectively by the protective structure.

Unlocking the potentials of gel conformance for water shutoff in fractured reservoirs: Favorable attributes of the double network gel for enhancing oil recovery

The double-network prepared with an in-situ monomer gel and a fast-crosslinked Cr(III) gel is introduced to develop a thixotropic and high-strength gel (THSG), which is found to have many advantages over the traditional gels. The THSG gel demonstrates remarkable thermal stability, and no syneresis is observed after 12 months with high salinity brine (95,500 mg/L). Moreover, the SEM and XRD results indicate that the gel is intercalated into the lamellar structures of Na-MMT, where the gel can form a uniform and compact structure. In addition, the THSG gel has an excellent swelling behavior, even in the high salinity brine. In the slim tube experiments, the THSG gel exhibits high rupture pressure and improves blocking capacity after being ruptured. The core flooding results show that a layer of gel filter cake is formed on the face of the fracture, which may be promoted by a high matrix permeability, a small aperture fracture, and a high injection rate. After the gel treatment, the fracture can be completely blocked by the THSG gel. It is found that a high incremental oil recovery (65.3%) can be achieved when the fracture was completely blocked, compared to 40.2% if the gel is ruptured. Although the swelling of ruptured gel can improve oil recovery, part of the injected brine may be channeled through the gel-filled fractures, resulting in a decrease in the sweep efficiency. Therefore, the improved blocking ability by gel swelling (e.g., in fresh water) may be less efficient to contribute to an enhancement of oil recovery. It is also found that the pressure gradient and residual resistance factor to water (Frrw) are higher if the matrix is less permeable, indicating that the fractured reservoir with lower matrix permeability may require a higher gel strength for treatment. The findings of this study may provide novel insights on designing robust double network gels for water shutoff in fractured reservoirs.

Model-constrained and data-driven double-supervision acoustic impedance inversion

Seismic impedance inversion is an important technique for structure identification and reservoir prediction.Model-based and data-driven impedance inversion are the commonly used inversion methods.In practice,the geophysical inversion problem is essentially an ill-posedness problem,which means that there are many solutions corresponding to the same seismic data.Therefore,regularization schemes,which can provide stable and unique inversion results to some extent,have been introduced into the objective function as constrain terms.Among them,given a low-frequency initial impedance model is the most commonly used regularization method,which can provide a smooth and stable solution.However,this model-based inversion method relies heavily on the initial model and the inversion result is band limited to the effective frequency bandwidth of seismic data,which cannot effectively improve the seismic vertical resolution and is difficult to be applied to complex structural regions.Therefore,we propose a data-driven approach for high-resolution impedance inversion based on the bidirectional long short-term memory recurrent neural network,which regards seismic data as time-series rather than image-like patches.Compared with the model-based inversion method,the data-driven approach provides higher resolution inversion results,which demonstrates the effectiveness of the data-driven method for recovering the high-frequency components.However,judging from the inversion results for characterization the spatial distribution of thin-layer sands,the accuracy of high-frequency components is difficult to guarantee.Therefore,we add the model constraint to the objective function to overcome the shortages of relying only on the data-driven schemes.First,constructing the supervisor1 based on the bidirectional long short-term memory recurrent neural network,which provides the predicted impedance with higher resolution.Then,convolution constraint as supervisor2 is introduced into the objective function to guarantee the reliability and accuracy of the inversion results,which makes the synthetic seismic data obtained from the inversion result consistent with the input data.Finally,we test the proposed scheme based on the synthetic and field seismic data.Compared to model-based and purely data-driven impedance inversion methods,the proposed approach provides more accurate and reliable inversion results while with higher vertical resolution and better spatial continuity.The inversion results accurately characterize the spatial distribution relationship of thin sands.The model tests demonstrate that the model-constrained and data-driven impedance inversion scheme can effectively improve the thin-layer structure characterization based on the seismic data.Moreover,tests on the oil field data indicate the practicality and adaptability of the proposed method.

Structured NiFe catalysts derived from in-situ grown layered double hydroxides on ceramic monolith for CO_(2) methanation

Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.

Hydrothermal Synthesis,Structure and Characterization of a New 2D Co(Ⅱ) Coordination Polymer Based on Flexible Double Imidazole Derivative and Oxalate

A 1D supramolecular compound [dmbbbi]（1） and a 2D cobalt coordination polymer [Co（dmbbbi）（ox）] 2（2） [dmbbbi=1,1-（1,4-butanediyl）bis（5,6-dimethylbenzimidazole）,ox=oxalate],C48H52Co2N8O8,were obtained under hydrothermal conditions by tuning the molar ratio of the reactants.The crystal structure analysis reveals that in compound 1,the adjacent dmbbbi molecules connect with each other via hydrogen bonds to form a 1D supramolecular chain.In compound 2,two crystallographically independent Co2＋ ions show the same six-coordination mode.Each Co2＋ ion is coordinated by four oxygen atoms from two ox anions and two nitrogen atoms from two cis-dmbbbi ligands.The adjacent Co2＋ ions are bridged by ox anions to generate an infinite 1D zigzag chain,which is extended by pairs of dmbbbi ligands to form a 2D honeycomb-like（6,3） network.Moreover,the thermal stability and the electrochemical property of compound 2 were studied.

Syntheses and Crystal Structures of Two New Mercury(Ⅱ) Complexes with Double Betaine Ligands

Reaction of HgCl2 and double betaine ligands in water at about 80 ℃ yielded two new Hg（Ⅱ） complexes,[Hg（L1）Cl2]·H2O 1 and [Hg2（L2）Cl4]·3HgCl2 2（L1 = 1,3-bis（pyridinio-4-carboxylato）-propane,L2 = 1,4-bis（pyridinio-4-carboxylato）-1,4-dimenthylbenzene）.Their struc-tures have been characterized by single-crystal X-ray diffraction techniques.The structure of 1 contains 1-D chains,in which the adjacent Hg（Ⅱ） atoms are bridged by L1 ligands in a syn-syn bis-monodentate mode.The chains are further connected through face-to-face π-π stacking interactions between pyridine rings to generate an infinite double-chain network.In 2,two Hg（Ⅱ） atoms are joined by L2 ligands in the same coordination mode as 1 to form an isolated dinuclear structure.The thermal stabilities of both complexes have also been investigated.

The Thermodynamic and Dynamical Features of Double Front Structures During 21-31 July 1998 in China

The daily 1°× 1° data of the Aviation （AVN） model, the black body temperature （TBB） data of cloud top, and cloud images by geostationary meteorological satellite （GMS） are used to identify a dew-point front near the periphery of the western Pacific subtropical high （WPSH）. The results clearly demonstrate the existence of the dew-point front, and its thermodynamic and dynamic structural characteristics are analyzed in detail. The dew-point front is a transitional belt between the moist southwest monsoon flow and the dry adiabatic sinking flow near the WPSH, manifested by a large horizontal moisture gradient in the mid-lower troposphere and conjugated with the mei-yu front to form a predominant double-front structure associated with intense rainfall in the mei-yu period. The mei-yu front is located between 30° and 35°N, vertically extends from the ground level to the upper level and shifts northward. The dew-point front is to the south of the mei-yu front and lies up against the periphery of the WPSH. Generally, it is located between 850 hPa and 500 hPa. On the dew-point front side, the southwesterly prevails at the lower level and the northeasterly at the upper level; this wind distribution is different from that on the mei-yu front side. Vertical ascending motion exists between the two fronts, and there are descending motions on the north side of the mei^yu front and on the south side of the dew-point front~ which form a secondary circulation. The dynamics of the double fronts also have some interesting features. At the lower level, positive vertical vorticity and obvious convergence between the two fronts are clearly identified. At the mid-lower level, negative local change of the divergence （corresponding to increasing convergence） is often embedded in the two fronts or against the mei-yu front. Most cloud clusters occur between the two fronts and propagate down stream in a wave-like manner.

Middle or low water pressure direct spiral double helix converging nozzle structure optimization and flow field analysis

In order to solve the problem of using new nozzle is proposed in fire rescue robot. middle or low water pressure to form fine water mist, a Existing water mist nozzles are basically used for high pressure and in large size, complex structure and poor low pressure atomization effect in comparison with requirement of snake-like fire rescue robots. On the basis of comprehensive typical spray noz- zles, a direct spiral double helix converging nozzle （DSDHCN） is proposed, which has the advanta- ges of small volume, light weight, simple structure, and convenient installation. To make the spray nozzle have good performance, and meet the requirements of more efficient fire extinguishing, a nu- merical study is carried out to analyze the internal and external full flow field of nozzle. A gas-liquid two-phase flow is applied to simulate the external full flow field of nozzle with VOF model in fluent software. The simulation results show the real situation of water flow out of the atomization nozzle and the water jet trajectory. Some simulations about middle or low water pressure direct spiral double he- lix converging optimized nozzle have been done in 30bar pressure. The simulation results show that the optimized nozzle structure not only makes the spray droplets have a good cone angle, but also have a sufficient axial velocity,which proves the structure rationality of the proposed optimized nozzle.

Synthesis and crystal structure of a novel double 1:11 series arsenotungstate: [Cu^I(phen)_2]_5H_6[Sm(AsW_(11)O_(39))_2]·6H_2O

A novel double 1：11 series arsenotungstate, [Cu^I（phen）2]5H6[Sm（AsW11O39）2]·6H2O （phen=1, 10-phenanthroline） was synthesized by the hydrothermal method and characterized by elemental analysis, 1R spectra, and single-crystal X-ray diffraction. The title compound was monoclinic, space group P2 1/c, a=3.75710（2） nm, b=1.39776（8） nm, c=-3.33735（18） nm, β=96.967（10）°, V=17.3969（17） nm^3, Z=4. Single crystal X-ray structural analyses revealed that the dimeric polyanion, [SmAs2W22O78]^1-, consisted of one central Sm^3＋ ion and two tetradentate heteropoly ligands [ASW11O39]^7-. The Sm^3＋ ion and two tetradentate defective [AsW11O39]^7- anions were joined together by the sharing of four oxygen atoms from each heteropoly ligand. The bond valence sum （BVS） calculations of the title compound suggested that all four Cu atoms were in the ＋1 oxidation sate.

Synthesis and Crystal Structure of a New One-dimensional Double Helical-chain Polymer, {Zn(O_2CC_(12)H_8CO_2)(H_2O)}_n

A new zinc polymer, {Zn（O2CC12H8CO2）（H2O）}, or {Zn（DPHA）（H2O）}n （O2CC12H8CO2, DPHA = 1,1′ -biphenyl-2,2′-dicarboxylate dianion） has been synthesized under hydrothermal conditions. The crystal is of monoclinic, space group P21/c with a = 12.8418（5）, b = 5.9505（2）, c = 17.2989（5） A, β = 104.020（2）°, V = 1282.52（8） A^3, C14H10O5Zn, Mr= 323.61, Z = 4, Dc = 1.676 g/cm^3,μ = 1.930 mm^-1, F（000） = 656, R = 0.0766 and wR = 0.1871 for 1775 observed reflections （I 〉 2σ（I））. It consists of Zn2（DPHA）2（H2O）2 units, which are further extended into a one-dimensional double helical-chain polymer via Zn-O bonding. The hydrogen bonding interactions extend the helical chains into a two-dimensional layer structure.

Experimental Study and Numerical Simulation of Hypervelocity Projectile Impact on Double-Wall Structure

Tests of hypervelocity projectile impact on double-wall structure were performed with the front wall ranging from 0.5 mm to 2.0 mm thick and different impact velocities. Smooth particle hydrodynamics (SPH) code in LS-DYNA was employed for the simulation of hypervelocity impact on the double-wall structure. By using elementary shock wave theory, the experimental results above are analyzed. The analysis can provide an explanation for the penetration mechanism of hypervelocity projectile impact on double-wall structure about the effect of front wall thickness and impact velocity..