摘要：Due to their tunable acidity,shape selectivity,and excellent stability,zeolites are of great importance as solid acid materials in industrial *** the properties of the acid sites in zeolites allows for the rational design and fabrication of catalysts for target *** ether(DME)carbonylation,a critical chain-growth reaction for C1 resource utilization,is selectively catalyzed by the Brønsted acid sites within the eight-membered rings(8-MRs)of mordenite(MOR).It is anticipated that strengthening the Brønsted acidity—particularly in 8-MRs—will improve the catalytic performance of *** this work,density functional theory(DFT)calculations are first employed and the results used to design a modified MOR with stannum(Sn)and to predict the corresponding changes in *** by the theoretical studies,a series of Sn-modified MOR are synthesized via a defect-engineering and subsequent heteroatom-substitution *** partial desilication,isolated tetrahedral Sn species in an open configuration are successfully synthesized for the first time,within which tetrahedrally coordinated Al sites are *** acidic characterization is used to confirm that the acidity of the Brønsted acid sites is enhanced by the introduction of the Sn species;as a result,the sample exhibits excellent activity in DME carbonylation *** and DFT studies reveal that this strengthened acidity facilitates the adsorption of DME and reduces the activation barriers of DME dissociation and acetyl formation,accounting for the improved *** work demonstrates mechanistic insights into the promoting effects of strong acidity on DME carbonylation and offers a promising strategy to precisely control the acidic strength of zeolites.

摘要：The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter *** particles,emerged as excitations around exotic band degeneracy points,continue to be reported in real materials and artificially engineered systems,but so far,we do not have a complete picture on all possible types of particles that can be ***,via systematic symmetry analysis and modeling,we accomplish a complete list of all possible particles in time-reversal-invariant *** includes both spinful particles such as electron quasiparticles in solids,and spinless particles such as phonons or even excitations in electric-circuit and mechanical *** establish detailed correspondence between the particle,the symmetry condition,the effective model,and the topological *** obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.

摘要：本文评估了拱形支撑结构周围的风流场特性,属于计算流体动力学的研究领域.通过与文献中风洞试验数据的对比,验证了数值模拟结果.本文不但给出了不同形状拱形支撑结构(尖顶、扁平和拱形结构)表面的平均、脉动、最大和最小风压系数,而且讨论了不同的风向和结构高径比对风压系数的影响.结果表明,与其他结构相比,尖顶结构表面的风压系数和湍流扰动在数值上较低.地形粗糙度指数越低,结构表面的平均风压系数越大.此外,对于尖顶结构,高径比的增加会导致结构表面风压的增加.与其他风向相比,来风角度为45°的情况下屋顶表面所受负风压最强.值得指出的是,本文对于不同风向和尖顶结构的详细研究结果可以对工程设计优化领域有一定的借鉴意义.

摘要：Non-hermiticity presents a vast newly opened territory that harbors new physics and applications such as lasing and ***,only non-Hermitian systems with real eigenenergies are stable,and great efforts have been devoted in designing them through enforcing parity-time(PT)*** this work,we exploit a lesser-known dynamical mechanism for enforcing real-spectra,and develop a comprehensive and versatile approach for designing new classes of parent Hamiltonians with real *** design approach is based on a new electrostatics analogy for modifed non-Hermitian bulk-boundary correspondence,where electrostatic charge corresponds to density of states and electric felds correspond to complex spectral *** such,Hamiltonians of any desired spectra and state localization profle can be reverse-engineered,particularly those without any guiding symmetry *** recasting the diagonalization of non-Hermitian Hamiltonians as a Poisson boundary value problem,our electrostatics analogy also transcends the gain/loss-induced compounding of foating-point errors in traditional numerical methods,thereby allowing access to far larger system sizes.

摘要：The problem of global stabilization by state feedback for a class of time-delay nonlinear system is considered. By constructing the appropriate Lyapunov-Krasovskii functionals (LKF) and using the backstepping design, a linear state feedback controller making the closed-loop system globally asymptotically stable is constructed.

摘要：Negative thermal expansion(NTE),as an abnormal physical behavior,has been followed by scientists’attention over the past 30 years,due to its fascinating physical mechanisms and the prospect of high-precision thermal expansion control[1-5].Although some NTE materials(alloys[6],cyanides[7],fluorides[8-10],nitrides[11],oxides[12,13],MOFs[14-16],etc.)have been found,their number and variety are still very small,limiting their *** and designing new NTE materials is an important and challenging topic for the development of the field of *** have been continually reviewing and summarizing obtained results to look to the future of NTE[17-23].

摘要：A flow control method based on an active jet is developed to restart hypersonic inlets. The dynamic restarting process is numerically reproduced by unsteady Reynolds averaged Navier-Stokes(RANS) modeling to verify the effectiveness and reveal the influence of jet conditions. The active jet improves the inlet unstart status by drawing the high-pressure separation bubble from the internal compression duct and performing a full expansion to alleviate the adverse pressure gradient. Moreover, the favorable pressure gradient in the inlet caused by jet expansion allows for a successful restart after turning off the jet. The influence of the jet momentum ratio is then analyzed to guide the design of the active jet control method and choose the proper momentum ratios. A low jet momentum does not eliminate the high-pressure separation bubble, whereas an excessive jet momentum causes severe momentum loss due to the induced shock. The general rule in restarting the inlet using an active jet is to allow a full jet expansion downstream of the jet slot while avoiding excessive momentum loss upstream and preventing the thick low-speed layer.

摘要：黄药对硫化矿具有很强的捕收性能,但其对黄铜矿和黄铁矿的分离效果不佳。为了有效地从黄铜矿中分离出黄铁矿,本文将四嗪硫铜官能团和疏水烃基结合,设计出一种新型的捕收剂-四嗪硫铜捕收剂。探究了四嗪硫铜捕收剂对黄铜矿和黄铁矿的浮选性能,并研究了四嗪硫铜捕收剂中不同的疏水烃链对浮选性能的影响。紫外实验结果表明,6-己基-6-甲基-1,2,4,5-四嗪-3-硫铜(HxMTT)易于与铜离子和亚铜离子结合,并在结合过程中释放氢离子进入溶液,但不易与铁离子和亚铁离子结合。原子力和接触角实验结果表明,HxMTT吸附在黄铜矿的表面,增加了黄铜矿表面的疏水性。红外和XPS实验结果进一步表明,HxMTT通过形成Cu—N和Cu—S键化学吸附在黄铜矿表面。

摘要：The gravity inversion is to restore genetic density distribution of the underground target to be explored for explaining the internal structure and distribution of the *** this paper,we propose a new 3D gravity inversion method based on 3D U-Net++.Compared with two-dimensional gravity inversion,three-dimensional(3D)gravity inversion can more precisely describe the density distribution of underground ***,conventional 3D gravity inversion method input is two-dimensional,the input and output of the network proposed in our method are *** the training stage,we design a large number of diversifi ed simulation model-data pairs by using the random walk method to improve the generalization ability of the *** the test phase,we verify the network performance by using the model-data pairs generated by the *** further illustrate the eff ectiveness of the algorithm,we apply the method to the inversion of the San Nicolas mining area,and the inversion results are basically consistent with the borehole measurement ***,the results of the 3D U-Net++inversion and the 3D U-Net inversion are *** density models of the 3D U-Net++inversion have higher resolution,more concentrated inversion results,and a clearer boundary of the density model.

摘要：Hybrid sodium-ion capacitors(SICs)bridge the gap between the supercapacitors(SCs)and batteries and have huge potential applications in large-scale energy ***,designing appropriate anode materials with fast kinetics behavior as well as long cycle life to match with the cathode electrodes remains a crucial ***,Nb2O5 nanotubes and nanowire-to-nanotube homo-junctions were directly grown on the carbon cloth(CC)via a simple hydrothermal process through regulating the pH value of *** as-prepared Nb2O5@CC nanotubes displayed a high reversible capacity of 175 mA hg-1 at the current density of 1Ag-1 with the coulombic efficiency of 97%after 1500 ***,the SICs fabricated with Nb2O5@CC and activated carbon(AC)electrode materials showed a high energy density of 195 W h kg-1 at 120 W kg-1,a power density of 7328 W kg-1 at 28 W hkg-1and 80%of the capacitance retention after 5000 ***,the flexible SIC devices can operate normally at various bendable *** Nb2O5@CC nanotubes in this work can be promising electrode materials in flexible and wearable energy storage devices.