High-Gain Scheduling of the Proportional-Integral-Observer

Estimation of states and unknown inputs simultaneously can be done by Proportional-Integral-Observer (PIO). This observer is used in nonlinear and robust control. It has additional integral feedback loop in comparison with the usual Luenberger observer. Increasing the gain of this observer the performance would be increased, however due to this high gain the performance is influenced by measurement noise. Advanced PI-Observer (API) algorithm is a method which is used for scheduling the optimal gain of PI-Observer based on the cost function and by using a bank of PI-Observer. In this contribution the proposed method obtains relative optimal gain by using a given cost function. Afterwards the absolute optimal gain is computed by changing the design parameters at each step based on the desired performance criteria. The absolute optimal gain is found instead of relative optimal gain in comparison with the API-Observer. Simulation results estimating contact forces acting to a vibrating elastic beam based on indirect measurements illustrate the improvement of the proposed method. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Performance study of the multiwavelet discontinuous Galerkin approach for solving the Green-Naghdi equations

This paper presents a multiresolution discontinuous Galerkin (DG) scheme for the adaptive solution of Boussinesq-type equations. The model combines multiwavelet (MW)–based grid adaptation with a DG solver based on the system of fully nonlinear and weakly dispersive Green-Naghdi (GN) equations. The key feature of the adaptation procedure is to conduct a multiresolution analysis using MWs on a hierarchy of nested grids to improve the efficiency of the reference DG scheme on a uniform grid by computing on a locally refined adapted grid. This way, the local resolution level will be determined by manipulating MW coefficients controlled by a single user-defined threshold value. The proposed adaptive multiwavelet DG solver for GN equations is assessed using several benchmark problems related to wave propagation and transformation in nearshore areas. The numerical results demonstrate that the proposed scheme retains the accuracy of the reference scheme, while significantly reducing the computational cost.     

One-Dimensional Matrix-Fracture Transfer in Dual Porosity Systems with Variable Block Size Distribution

Most of the developed models for fractured reservoirs assume ideal matrix block size distribution. This assumption may not be valid in reality for naturally fractured reservoirs and possibly lead to errors in prediction of production from the naturally fractured reservoirs especially during a transient period or early time production from the matrix blocks. In this study, we investigate the effect of variable block size distribution on one- dimensional flow of compressible fluids in fractured reservoirs. The effect of different matrix block size distributions on the single phase matrix-fracture transfer is studied using a recently developed semi-analytical approach. The proposed model is able to simulate fluid exchange between matrix and fracture for continuous or discrete block size distributions using probability density functions or structural information of a fractured formation. The presented semi-analytical model demonstrates a good accuracy compared to the numerical results. There have been recent attempts to consider the effect of variable block size distribution in naturally fractured reservoir modeling for slightly compressible fluids with a constant viscosity and compressibility. The main objective of this study is to consider the effect of variable block size distribution on a one-dimensional matrix-fracture transfer function for single-phase flow of a compressible fluid in fractured porous media. In the proposed semi-analytical model, the pressure variability of viscosity and isothermal compressibility is considered by solving the nonlinear partial differential equation of compressible fluid flow in the fractured media. The closed form solution provided can be applied to flow of compressible fluids with variable matrix block size distribution in naturally fractured gas reservoirs.     

Synthesis and Reactivity of Functionalized Binary and Ternary Thiometallate Complexes [(RT)4S6], [(RSn)3S4]2−, [(RT)2(CuPPh3)6S6], and [(RSn)6(OMe)6Cu2S6]4− (R=C2H4COOH,CMe2CH2COMe; T=Ge,Sn)

Caged chalcogens : A series of novel, functionalized T_nS_m cages (T=Ge, Sn; n/m=4:6, 3:4) with terminal COO(H) or COMe groups were synthesized and show further reactivity toward Cu^I complexes (an example of which is shown here) and to hydrazines. This led to the generation of functionalized Cu/T/S clusters or the formation of Schiff bases at the C?O groups, respectively, with or without further fragmentation of the T/S core.

     

Effect of 2D Image Resolution on 3D Stochastic Reconstruction and Developing Petrophysical Trend

Multi-resolution digital rock physics (DRP) makes it possible to up-scale petrophysical properties from micron size to core sample size using two-dimensional (2D) thin section images. Resolution of 3D images and sample size are challenging problems in DRP where high-resolution images are acquired from small samples using inefficient and expensive micro-CT facilities. Three-dimensional stochastic reconstruction is an alternative approach to overcome these challenges. In this paper, we use multi-resolution images and investigate effect of 2D image resolution on 3D stochastic reconstruction and development of petrophysical trends for our two sandstone and carbonate original representative volume elements (RVEs). The proposed method includes three steps. In the first step, the spatial resolution of our original RVEs is decreased synthetically. In the second step, stochastic RVEs are realized for each resolution using two perpendicular images, correlation functions, and phase recovery algorithm. In the reconstruction method, a full set of two-point correlation functions (TPCFs) is extracted from two perpendicular 2D images. Then TPCF vectors are decomposed and averaged to realize 3D stochastic RVEs. In the third step, petrophysical properties like relative and absolute permeability as well as porosity and formation factor are computed. The output is used to develop trends for petrophysical properties in different resolutions. Experimental results illustrate that the proposed method can be used to predict petrophysical properties and reconstruct 3D RVEs for resolutions unavailable in the acquired 2D or 3D data.     

The effects induced by proton irradiation on structural characteristics of nuclear graphite

A grade TSX graphite was irradiated by a 2.5 MeV proton and a dose of 1.47 × 10¹⁸ ion cm⁻² at 330 K. The displacement per atom under this irradiation condition was about 0.02. The lattice parameter, crystallite size and the vacancies density in the graphite was measured before and after irradiation. It was found that the proton irradiation led to an increase in the volume of the sample. The volume change in the irradiated sample was confirmed by atomic force and scanning electron microscopes observations as increased roughness and pore size. Also, FTIR results showed that graphite is slightly oxidized by irradiation.

     

Baryogenesis in f(R,T) Gravity

We study gravitational baryogenesis in the context of f(R, T) gravity where the gravitational Lagrangian is given by a generic function of the Ricci scalar R and the trace of the stress-energy tensor T. We explore how this type of modified gravity is capable to shed light on the issue of baryon asymmetry in a successful manner. We consider various forms of baryogenesis interaction and discuss the effect of these interaction terms on the baryon to entropy ratio in this setup. We show that baryon asymmetry during the radiation era of the expanding universe can be non-zero in this framework. Then, we calculate the baryon to entropy ratio for some specific f(R, T) models and by using the observational data, we give some constraints on the parameter spaces of these models.     

A Priori Estimation of Organic Reaction Yields

A thermodynamically guided calculation of free energies of substrate and product molecules allows for the estimation of the yields of organic reactions. The non‐ideality of the system and the solvent effects are taken into account through the activity coefficients calculated at the molecular level by perturbed‐chain statistical associating fluid theory (PC‐SAFT). The model is iteratively trained using a diverse set of reactions with yields that have been reported previously. This trained model can then estimate a priori the yields of reactions not included in the training set with an accuracy of ca. ±15 %. This ability has the potential to translate into significant economic savings through the selection and then execution of only those reactions that can proceed in good yields.     

New mercury(II) and cadmium(II) complexes with (p-methylbenzoyl)methylene triphenylphosphorane: Synthesis,spectroscopic and structural characterization

Reaction of Ph₃PCHCOC₆H₄Me (L), with HgX₂ and CdCl₂·H₂O in methanol with equimolar ratios give binuclear complexes of the type [MX(μ-X){CH(PPh₃)C(O)C₆H₄Me}]₂ (M = Hg; X = Cl (1), Br (2), I (3), M = Cd; Cl(4)). The bridge-splitting reaction of binuclear complexes [MX(μ-X){CH(PPh₃)C(O)C₆H₄Me}]₂ by dimethyl sulfoxide (DMSO) yields the mononuclear complexes [MX₂{CH(PPh₃)C(O)C₆H₄Me}(OSMe₂)] (M = Hg; X = Cl (5), Br (6), I (7), M = Cd; Cl (8)). The characterization of these complexes was carried out by elemental analysis and FT-IR, ¹H, ³¹P, and ¹³C NMR spectroscopies. C-coordination of ylide and O-coordination of DMSO are demonstrated by single-crystal X-ray analysis of mononuclear complex of [HgBr₂{CH(PPh₃)C(O)C₆H₄Me}(OSMe₂)] (6). Complex 6 is monomeric with tetrahedral geometry around the metal ion.