Optimum Shape Design Using Automatic Differentiation in Reverse Mode

This paper shows how to use automatic differentiation in reverse mode as a powerful tool in optimization procedures. It is also shown that for aerodynamic applications the gradients have to be as accurate as possible. In particular, the effect of having the exact gradient of he first or second order spatial discretization schemes is presented. We show that the loss of precision in the gradient affects not only the convergence, but also the final shape. Both two and three dimensional configurations of transonic and supersonic flows have been investigated. These cases involve up to several thousand control parameters

A simplified approach to the magnetic blue shift of Mott gaps

The antiferromagnetic ordering in Mott insulators upon lowering the temperature is accompanied by a transfer of the single-particle spectral weight to lower energies and a shift of the Mott gap to higher energies (magnetic blue shift, MBS). The MBS is governed by the double exchange and the exchange mechanisms. Both mechanisms enhance the MBS upon increasing the number of orbitals. We provide an expansion for the MBS in terms of hopping and exchange coupling of a prototype Hubbard-Kondo-Heisenberg model and discuss how the results can be generalized for application to realistic Mott or charge-transfer insulator materials. This allows estimating the MBS of the charge gap in real materials in an extremely simple way avoiding extensive theoretical calculations. The approach is exemplarily applied to $\alpha$-MnTe, NiO, and BiFeO$_3$ and an MBS of about $130$ meV, $360$ meV, and $157$ meV is found, respectively. The values are compared with the previous theoretical calculations and the available experimental data. Our ready-to-use formula for the MBS simplifies the future studies searching for materials with a strong coupling between the antiferromagnetic ordering and the charge excitations, which is paramount to realize a coupled spin-charge coherent dynamics at a femtosecond time scale.Comment: 16 pages, 13 figure

Online Novel Techniques for Selective Simultaneous Determination of Alkalinity/Bicarbonate and Hardness in Drinking Water by Skalar San++ Segmented Flow Analysis.

The procedures of the current novel automated technique for the determination of hardness, Carbonate, bicarbonate and alkalinity in drinking water have been modified from both classical batch titration and the method of the flow analysis Skalar San++ method (classical scalar current).  The forms of standards in the current methods have been modified. The calcium chloride used previously in the current method for the determination of both calcium and total hardness was replaced by a mixed standard that contains calcium and magnesium carbonate in an aqueous solution. Likewise, calcium carbonate and sodium bicarbonate standards currently used in determination of alkalinity and bicarbonate respectively were replaced by using only one standard of calcium, sodium carbonate salt, and the required bicarbonate concentrations were derived from the same calcium carbonate formula mathematically in the stoichiometry equation. The new approach method was validated and applied successfully for analysis of drinking water and proficiency tests samples (PTS).The technique is used for an automatic online analysis of total, calcium hardness, total alkalinity and bicarbonate in drinking water covering a range of 10 - 100 ppm for total hardness and calcium hardness and a range of 5-100 ppm for alkalinity and bicarbonate mg/L as CaCO3. The method gave a distinct merit over the manual titration method and the current skalar method, with enhanced detection limit, high precision (RSD) which was found to be less than 1%) and accuracy of ( ± 1-2%), as well as a high spectral peak resolution and sample throughput.. Moreover, additional merits of the proposed method over the classical  skalar one, other than being economic in use, as there is some chemical cut off, is the feasibility of the automatic determination of carbonate ions  concentrations in the same run, which could not be achieved automatically by the classical skalarc method, as  it always  needs mathematical subtraction of bicarbonate concentration from alkalinity concentrations from multi runs. The latter approach is tedious, involved lots of reagents and procedures, time consuming, and could impact the overall method precision and accuracy. The methoddemonstrated selectivity as online automated approach for selective determination of total hardness and calcium hardness in one run and determination of total alkalinity and bicarbonate from the same standard in the second run, when keeping all of the four chemistry reagents aspirated automatically. Sole analysis for every parameter as in the current method was achieved demonstrating simultaneous analysis without discernment, the recovery was found  to be comparable with the novel proposed method, but  the latter gave  a marked enhancement in precision  and peak resolution.. Analysis for drinking water samples gave quantitative results with Z score of less than ± 1.2. Accuracy of the automated analysis was investigated by multiple techniques including recovery by standard addition method, run of CRM and t test statistical analysis. The merit of the accuracy for this proposed method has been demonstrated successfully through applications to real samples

Magnetic blue shift of Mott gaps enhanced by double exchange

A substantial energy gap of charge excitations induced by strong correlations is the characteristic feature of Mott insulators. We study how the Mott gap is affected by long-range antiferromagnetic order. Our key finding is that the Mott gap is increased by the magnetic ordering: A magnetic blue shift (MBS) occurs. Thus the effect is proportional to the exchange coupling in the leading order in the Hubbard model. In systems with additional localized spins the double-exchange mechanism induces an additional contribution to the MBS which is proportional to the hopping in the leading order. The coupling between spin and charge degrees of freedom bears the potential to enable spin-to-charge conversion in Mott systems on extreme time scales determined by hopping and exchange only, since a spin-orbit-mediated transfer of angular momentum is not involved in the process. In view of spintronic and magnonic applications, it is highly promising to observe that several entire classes of compounds show exchange and double-exchange effects. Exemplarily, we show that the magnetic contribution to the band-gap blue shift observed in the optical conductivity of α-MnTe is correctly interpreted as the MBS of a Mott gap

The Behaviour of Swine

The pig was a forest-dwelling animal from the beginning of its history. In some parts of the world it has been domesticated for at least 7000 years. The European breeds of domestic swine were derived from the local wild pig, Sus scrofa. Herds ranged in pastures and forests and kept indoors only for fattening. The breeds in the Far East were derived from another wild pig, Sus vittatus, a smaller animal with shorter legs and a higher reproductive ability (Mohr 1960; Zeuner 1963). The two types interbred readily. The modem breeds of pig evolved from different crossings between the two original types. They form a rich diversity of genetic material and more than 200 breeds have been catalogued. Certain wild types of pig-like animals, such as the African bush pig (Pontamochoerus larvatus) and the wart hog (Phacochoerus aethiopecus), have never been domesticated. The basis of the social structure in feral swine is the matriarchal herd: one or several females with their offspring. The males are not permanently associated to such herds, often ranging solitary or in \u27bachelor\u27 groups (Fig. 52). Under domestication the pig has been modified from a pugnacious, free-ranging, foraging beast to a more docile animal which is handled readily in large groups under conditions of confined rearing. The behavioural plasticity of swine is emphasized by the rapidity with which wild pigs have adapted to rearing in restricted conditions. Although most of our knowledge of the behaviour of swine has been gained from data collected incidentally to research on nutrition, breeding, physiology and management, a number of experimental studies have recently appeared in learning, adaptation, social, sexual and maternal behaviours, making the pig the best known species among domestic mammals, from the point of view of behaviour

From Gapped Excitons to Gapless Triplons in One Dimension

Often, exotic phases appear in the phase diagrams between conventional phases. Their elementary excitations are of particular interest. Here, we consider the example of the ionic Hubbard model in one dimension. This model is a band insulator (BI) for weak interaction and a Mott insulator (MI) for strong interaction. Inbetween, a spontaneously dimerized insulator (SDI) occurs which is governed by energetically low-lying charge and spin degrees of freedom. Applying a systematically controlled version of the continuous unitary transformations (CUTs) we are able to determine the dispersions of the elementary charge and spin excitations and of their most relevant bound states on equal footing. The key idea is to start from an externally dimerized system using the relative weak interdimer coupling as small expansion parameter which finally is set to unity to recover the original model.Comment: 18 pages, 10 figure

Simple approach to thieno[3,2-d]pyrimidines as new scaffolds of antimicrobial activities

6-(4-Chlorophenyl)-spiro[cyclohexane-1,2-thieno[3,2-d][1,3]oxazin]-4(1H)-one (1) was synthesized and used as a starting material for the synthesis of a novel series of spiro compounds having biologically active sulfonamide (2a-e) and 3-(4-acetylphenyl)-6-(4-chlorophenyl)-1H-spiro[cyclohexane-1,2-thieno[3,2-d]pyrimidine-4(3H)-one (3). Compound 2a was used as a key intermediate for the synthesis of sulfonyl carbothioamide derivatives (4a-c). Also, compound 3 was used as an intermediate for the synthesis of 3H-spiro[cyclohexane-1,2-thieno[3,2-d]pyrimidin]-3-yl]phenyl}-2-imino-4-(substituted phenyl and/or thienyl)-1,2-dihydropyridine-3-carbonitrile derivatives (5a-e), 3H-spiro[cyclohexane-1,2-thieno[3,2-d]pyrimidin]-3-yl]phenyl}-2-oxo-4-(substituted phenyl and/or thienyl)-1,2-dihydropyridine-3-carbonitrile derivatives (6a-e), and 4-[(2Z)-3-substituted-arylprop-2-enoyl]phenyl-1H-spiro[cyclohexane-1,2-thieno[3,2-d]pyrimidine derivatives (7a-e). Cyclocondensation of 7a-e with hydrazine hydrate produced 6-(4-chlorophenyl)-3-[4-(5-substituted aryl-4,5-dihydro-1H-pyrazol-3-yl)phenyl]-1H-spiro[cyclohexane-1,2-thieno-[3,2-d]pyrimidin]-4(3H)-ones (8a-e), but with hydroxylamine hydrochloride afforded the corresponding isoxazoline derivatives (9a-e). Also, cyclocondensation by thiourea afforded 2-thioxo-1,2-dihydropyrimidin-4-yl)-phenyl-spiro-{cyclohexanethieno[3,2-d]pyrimidin}-4-one derivatives (10a-e). The new compounds were investigated for antimicrobial activity. Compounds 2c, 8b, c, 9b and 10b were the most potent ones against both Gram-negative and Gram-positive bacteria. Compound 8c exhibited higher antifungal activity towards the examined fungi with MIC of 1–2 µmol mL–1 compared to ketoconazole (MIC 2–3 µmol mL–1)

Corrosion Protection Enhancement on Aluminum Alloy And Magnesium Alloy by Mo-CeO2 conversion coating

AbstractIn this paper, Mo-CeO2 conversion coating was developed to protect Aluminum 2024 alloy and Magnesium AZ31 alloy against corrosion.The cerium oxide was incorporated in Molybdenum conversion coating which is considered as a promising alternative to replace chromate compounds. The corrosion efficacy was improving and has been characterized by polarization curves and EIS measurements.The structural and the microstructural Mo-CeO2 conversion coating was characterized by AFM, SEM and XRD and the mechanical proprieties was determined by nano indentation. The presence of molybdenum and oxide of cerium was confirmed with good physical and mechanical proprieties.The presence of CeO2 in the conversion coating had a beneficial effect on the corrosion resistance of the both materials

A high-finesse Fabry-Perot cavity with a frequency-doubled green laser for precision Compton polarimetry at Jefferson Lab

A high-finesse Fabry-Perot cavity with a frequency-doubled continuous wave green laser (532~nm) has been built and installed in Hall A of Jefferson Lab for high precision Compton polarimetry. The infrared (1064~nm) beam from a ytterbium-doped fiber amplifier seeded by a Nd:YAG nonplanar ring oscillator laser is frequency doubled in a single-pass periodically poled MgO:LiNbO$_{3}$ crystal. The maximum achieved green power at 5 W IR pump power is 1.74 W with a total conversion efficiency of 34.8\%. The green beam is injected into the optical resonant cavity and enhanced up to 3.7~kW with a corresponding enhancement of 3800. The polarization transfer function has been measured in order to determine the intra-cavity circular laser polarization within a measurement uncertainty of 0.7\%. The PREx experiment at Jefferson Lab used this system for the first time and achieved 1.0\% precision in polarization measurements of an electron beam with energy and current of 1.0~GeV and 50~$\mu$A.Comment: 20 pages, 22 figures, revised version of arXiv:1601.00251v1, submitted to NIM