Relaxed Stability Criteria for Time-Delay Systems:A Novel Quadratic Function Convex Approximation Approach

This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying delays.By introducing two adjustable parameters and two free variables,a novel convex function greater than or equal to the quadratic function is constructed,regardless of the sign of the coefficient in the quadratic term.The developed lemma can also be degenerated into the existing quadratic function negative-determination(QFND)lemma and relaxed QFND lemma respectively,by setting two adjustable parameters and two free variables as some particular values.Moreover,for a linear system with time-varying delays,a relaxed stability criterion is established via our developed lemma,together with the quivalent reciprocal combination technique and the Bessel-Legendre inequality.As a result,the conservatism can be reduced via the proposed approach in the context of constructing Lyapunov-Krasovskii functionals for the stability analysis of linear time-varying delay systems.Finally,the superiority of our results is illustrated through three numerical examples.

A COMBINED TECHNIQUE FOR SOLUTION OF PDE＇s VIA THE GENERALIZED DOMAIN DECOMPOSITION METHOD

The Domain Decomposition Method(DDM) is a powerful approach to solving maily types of PDE's. DDM is especially suitable for massively Parallel computers. In the past, most research on DDM has focused on the domain splitting technique. In this paper. we focus our attention on use of a combination of techniques to solve each subproblem. The central question with DDM is that of how to doal with the pseodoboundary conditions. Here, we introduce a set of operators which act on the pseudo-boundaries in the solution process, referring to this new. procedure as the 'Generalized Domain Decomposition A.Jlethod(GDDM).' We have already obtained convergence factors for GDDM with certain classes of PDE's. These ctonvergence factors show that we can derive exact solutions of the whole problem for certain types of PDE's, and can get superior speed of convergence for other types.

Study on Extraction of Oolong Tea Assisted by Ultrasonic Wave and 4C Technique and Its Application

[Objectives]The extraction conditions of formula oolong tea were investigated by an orthogonal experiment.[Methods]The technical conditions were optimized by the 4C method,and the application of formula oolong tea extract in cigarettes was studied.[Results]①In the experimental range,the best sensory evaluation effect of formula oolong tea extract was obtained with extraction conditions of 70%ethanol as extraction solvent,extraction time h,extraction temperature 25℃,and ultrasonic frequency 80 kHz,and follow-up low-temperature concentration,low-temperature sedimentation and low-temperature centrifugation.②The effects of different centrifugal speeds on the quality of formula oolong tea extract were explored.The formula oolong tea extract obtained under the conditions of 3000 r/min and centrifugal time of 10 min showed the best evaluation effect with soft and delicate smoke,rich smoke fragrance,good comfort and refreshing mouthfeel.③The effective aroma components in the formula oolong tea extract were qualitatively analyzed by GC-MS.[Conclusions]This study provides high-quality raw materials and a theoretical basis for the research of independent flavor blending in cigarette industry enterprises.

A novel SAXS/XRD/XAFS combined technique for in-situ timeresolved simultaneous measurements

Synchrotron radiation based combined technique can provide multiple structural information simultaneously,which is an important development direction of structural detection.In this study,a novel small-angle X-ray scattering/X-ray diffraction/X-ray absorption fine structure(SAXS/XRD/XAFS)combined setup was constructed,where an area detector,a curved detector,and a point detector are,respectively,used for the measurements of SAXS,XRD,and XAFS signals.A detailed description about the combined setup was given.A minitype diamond detector coupled to a SAXS beamstop was used to record the transmitted X-ray intensity,making the scattering(SAXS and XRD)signal measurement compatible with the absorption(XAFS)signal measurement,avoiding mechanical switching.The two-way sampling strategy was used to acquire XAFS signals,shortening the non-counting time.The two-way and one-way sampling strategies were discussed.High-frequency sampling scheme was used to collect experimental signals,improving the measurement efficiency and signal-to-noise ratio.A detailed description and discussion about the high-frequency scheme were also given in this paper.Except the rotation of monochromator,there is no mechanical movement in measurements,time resolution may reach the level of seconds.Using this SAXS/XRD/XAFS combined setup,SAXS,XRD,and XAFS signals can be acquired simultaneously.With some in-situ sample environment system,the newlydeveloped combined technique can be used to track the structure evolution in complex fluids.During the formation processes of(BiO)2CO3 and ZnAPO-34 particles,the changes of in-situ experimental data with reaction time demonstrate that SAXS/XRD/XAFS combined technique is feasible to track the dynamic process.

Nanosized cobalt-based catalyst prepared by supercritical phase condition for Fischer-Tropsch synthesis

A series of nanosized Co/Zn/Mn/K composite catalysts for Fischer-Tropsch synthesis （FTS） were prepared by supercritical fluid drying （SCFD） method and common drying （CD） method. The nanosized cobalt-based catalysts were characterized by XRD, TEM and BET techniques. Their catalytic performances were tested in a slurry-bed reactor under FTS reaction conditions. The drying and crystallization were carried out simultaneously during SCFD, therefore, the catalysts prepared by SCFD method have ideal structure and show the FTS performance superior to the others prepared by CD method. The FTS activity and selectivity were improved via adding Zn, Mn and K promoters, and less CH4 and CO2 as well as higher yield of C5＋ products were achieved. The optimal performance of a 92% CO conversion and a 65% C5＋ product yield was obtained over a catalyst with the component of Co/Zn/Mn/K = 100/50/10/7. Furthermore, the catalytic performance was studied under the conditions of liquid-phase and supercritical phase slurry-bed, and C5＋ product yield were 57.4% and 65.4%, respectively. In summary, better catalytic performance was obtained using the nanosized catalyst prepared by SCFD method under supercritical reaction conditions, resulting in higher conversion of CO, less CO2 byproduct, and higher yield of C5＋ products.

Coherent beam combination of two fiber amplifiers with multi-dithering technique

Coherent beam combination of two W-level fiber amplifiers with multi-dithering technique is demonstrated.In the experiment,the master laser is split into two channels.Multi-dithering technique is used for phase control.One channel is modulated with a 100 kHz sine wave produced by signal generator,and DSP lock-in amplifier is used for electric signal processing in the feedback loop.When the phase control loop is off,the far field interference pattern is blurred and dynamic with 20% fringe contrast.When the feedback loop is closed,the far field interference pattern is clear and stable with 72% fringe contrast,and 75% coherent combination efficiency is achieved.

A Procedure of Combination of Sequential Internal Thoracic Artery Grafting and Cooley's Technique for Complicated Case With Multi-vessel Disease,Left Ventricular Aneurysm and Mitral Regurgitation

INTRODUCTIONLeft ventricular aneurysm and ischemic mitral regurgitation are two of most common complications of acute myocardial infarction （AMI）. Combination of both these two fatal complications is not rare and the management of these complicated cases is always a challenge to cardiac surgeon because of its relatively high mortality. We reported a rare case of AMI in which a singlestage correction of mitral valve replacement with preservation of mitral apparatus, sequential left internal thoracic artery （ITA） grafting and Cooley＇s technique.

Selected Recent Applications of Sparse Grids

Sparse grids have become a versatile tool for a vast range of applications reaching from interpolation and numerical quadrature to data-driven problems and uncertainty quantification.We review four selected real-world applications of sparse grids:financial product pricing with the Black-Scholes model,interactive explo-ration of simulation data with sparse-grid-based surrogate models,analysis of simu-lation data through sparse grid data mining methods,and stability investigations of plasma turbulence simulations.

An ADI Sparse Grid method for Pricing Efficiently American Options under the Heston Model

One goal of financial research is to determine fair prices on the financial market.As financial models and the data sets on which they are based are becoming ever larger and thus more complex,financial instruments must be further developed to adapt to the new complexity,with short runtimes and efficient use of memory space.Here we show the effects of combining known strategies and incorporating new ideas to further improve numerical techniques in computational finance.In this paper we combine an ADI(alternating direction implicit)scheme for the temporal discretization with a sparse grid approach and the combination technique.The later approach considerably reduces the number of“spatial”grid points.The presented standard financial problem for the valuation of American options using the Heston model is chosen to illustrate the advantages of our approach,since it can easily be adapted to other more complex models.