A GUI driven Σ-Δ modulator design, evaluation and measurement tool with a view to practical implementation

A user-friendly design tool created in the MATLAB/Simulink environment to speed up the design, analysis, evaluation and measurement of single-loop and multistage sigma-delta (Sigma-Delta) modulators at the system level is presented in this paper. The tool covers a variety of Simulink-based design topologies of low-pass, band-pass and high-pass Sigma-Delta modulators

Chemical potential of oxygen for iron-rutile-ilmenite and iron-ilmenite-ulvospinel equilibria

The chemical potential of oxygen corresponding to the iron-rutile-ilmenite (IRI) and iron-ilmenite-ulvospinel (IIU) equilibria has been measured employing solid-state galvanic cells, Pt, Fe + TiO2 + FeTiO3//Fe+FeO, Pt and Pt, Fe + FeTiO3 + Fe2TiO4//(Y2O3) ZrO2//Fe+FeO, Pt in the temperature range of 875 to 1275 K and 900 to 1373 K, respectively. The cells are written such that the right-hand electrodes are positive. The electromotive force (emf) of both the cells was found to be reversible and to vary linearly with temperature over the entire range of measurement. The chemical potential of oxygen for IRI equilibrium is represented by ΔμO2(IRI) = -550,724 - 29.445T + 20.374T InT(±210) J mol-1 (875 ≤T≤ 1184 K) = -620,260 + 369.593T - 27.716T lnT(±210) J mol-1 (1184≤T≤ 1275 K) and that for IIU equilibrium by Δµ o2(IIU) = -501,800 - 49.035T + 20.374T lnT(±210) J mol-1 (900 ≤T≤ 1184 K) = -571,336 + 350.003T- 27.716T lnT(=-210) J mol-1 (1184 ≤T≤ 1373 K) The standard Gibbs energy changes for IRI and IIU equilibria have been deduced from the measured oxygen potentials. Since ilmenite contains small amounts of Ti3+ ions, a correction for the activity of FeTiO3 has been incorporated by assuming ideal mixing on each cation sublattice in the FeTiO3-Ti2O3 system. Similarly, the ulvospinel contains some Fe3+ ions and a correction for the activity of Fe2TiO4 has been included by modeling the Fe2TiO4-Fe3O4 system. The third-law analysis of the results obtained for IRI equilibrium gives ΔH 298 0 = -575 (±1.0) kJ mol-1 and for IIU equilibrium yields ΔH 298 0 = -523.7 (±0.7) kJ mol-1}. The present results suggest that Fe2+ and Ti4+ cations mix almost ideally on the octahedral site of spinel lattice in Fe2TiO4, giving rise to a configurational contribution of 2R In 2 (11.5256 J mol-1 K-1) to the entropy of Fe2TiO4

Thermodynamic stability of K β-alumina

The activity of K2O in a mixture of α-alumina and Kβ-alumina has been determined using the solid state galvanic cell: Ta, Bi-5 mol pct K // α-alumina + Kβ-alumina // In + In2O3, Ta in the temperature range 600 to 1000 K. The cell is written such that the right hand electrode is positive. The solid electrolyte consisted of a dispersion of α-alumina (~15 vol pct) in a matrix of Kβ-alumina. The emf of the cell was found to be reversible and to vary linearly with tem-perature. From the emf and auxiliary data on In2O3 and K2O from the literature, the activity of K2O in the two-phase mixture is obtained as log aK2O = 2.368 -20,850/T(K) (±0.015) The standard free energy of formation of Kβ-alumina from component oxides is given by K2O (s) + 9.5 β-Al2O3 (s) ΔK2O·9.5A12O3 (s) ΔG° = -398,920 + 45.01 T(K) (±1000) J mol-1

Revisiting scaling relations for giant radio halos in galaxy clusters

Many galaxy clusters host Megaparsec-scale radio halos, generated by ultrarelativistic electrons in the magnetized intracluster medium. Correlations between the power of radio halos and the thermal properties of the hosting clusters were established in the last decade, including the connection between the presence of a halo and cluster mergers. The X-ray luminosity and redshift limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for statistical studies of the halos. We uniformly analyze the radio and X-ray data for the GMRT cluster sample, and use the new Planck SZ catalog, to revisit the correlations between the power of halos and the thermal properties of galaxy clusters. We find that the radio power of halos at 1.4 GHz scales with the cluster X-ray (0.1--2.4 keV) luminosity computed within R_500 as P_1.4 L_500^2.0. Our bigger and more homogenous sample confirms that the X-ray luminous (L_500 > 5x10^44 erg/s) clusters branch into two populations --- radio halos lie on the correlation, while clusters with upper limits to radio-halo emission are well below that correlation. This bimodality remains if we excise cool cores from the X-ray luminosities. Correlating with Planck data, we find that P_1.4 scales with the cluster integrated SZ signal within R_500 as P_1.4 Y_500^2.1, in line with previous findings. However, contrary to previous studies that were limited by incompleteness and small sample size, we find that the "SZ-luminous" Y_500 > 6x10^-5 Mpc^2 clusters show a bimodal behavior similar to that in the radio-X-ray diagram. Bimodality of both correlations can be traced to clusters dynamics, with radio halos found exclusively in merging clusters. These results confirm the key role of mergers for the origin of giant radio halos, suggesting that they trigger the relativistic particle acceleration.Comment: 16 pages, 7 figures, accepted for publication in ApJ on September 12, 201

Environmentally sustainable facile synthesis of nanocrystalline holmium hafnate (Ho2Hf2O7): Promising new oxide-ion conducting solid electrolyte

A2B2O7 oxides with defect-fluorite structure are one of the potential candidates for solid oxide fuel cell electrolyte material due to their excessive thermodynamic stability in oxygen potential gradient at elevated temperature between 500 and 900 °C. Holmium hafnate nanoparticles have been synthesised through the Leeds Alginate Process (LAP) using inorganic salts of holmium and hafnium as starting materials immobilized in alginate beads. Ion exchange with sodium alginate and its subsequent thermal treatment have been used to prepare the nanopowder of Ho2Hf2O7. Thermal decomposition of dried beads is carried out at 700 °C for 2 h and 6 h to obtain the nanoparticles of Ho2Hf2O7. This calcination temperature was determined after carrying out simultaneous thermogravimetric analysis and differential scanning calorimetry (TGA/DSC). High Temperature X-ray Diffraction (HT-XRD) was carried out to gain further insight into the thermal decomposition process in static ambient environment. HT-XRD analysis corroborated with the results obtained from TGA/DSC. Nano-crystalline powder of single phase Ho2Hf2O7 has been obtained by calcination of oven dried ion-exchanged alginate beads in relatively low temperature range of 500–700 °C. Rietveld refinement of X-ray diffraction (XRD) data confirmed the formation of single phase defect fluorite structure of Ho2Hf2O7. The crystallographic parameters calculated from TEM and XRD analysis are in excellent agreement with each other. Furthermore, TEM–EDX analysis confirms that the Ho2Hf2O7 synthesised by the facile alginate process is nearly stoichiometric. Raman spectroscopy gives evidence of the presence of oxide-ion vacancy in holmium hafnate which is supported with ac-impedance spectroscopy measurement at selected three temperatures. The present study suggests that the LAP has the capability of yielding on a large scale single phase defect-fluorite nanoparticles of electrolyte materials for solid oxide fuel cells in environmentally sustainable, economical and energy efficiently manner

Oxygen potentials, Gibbs' energies and phase relations in the Cu-Cr-O system

Thermodynamic properties of ternary compounds, cuprous and cupric chromites (CuCrO2, CuCr204), and oxygen potentials corresponding to three three-phase regions in the Cu-Cr-O system have been measured in the temperature range 900 to 1350 K using a solid state galvanic cell incorporating calcia-stabilized zirconia. Cuprous chromite was found to be nearly stoichiometric. The compositions of non-stoichiometric cupric chromite saturated with CuO and Cr203 have been determined using electron microprobe and energy dispersive X-ray analysis. The results of this study resolve discrepancies in Gibbs" energies of cuprous and cupric chromites reported in the literature. A ternary phase diagram for the Cu-Cr-O system at 1150 K and phase relations in air for the Cu20-CuO-Cr203 system as a function of temperature have been derived based on the new thermodynamic data. The phase diagram given in the literature is found to be inaccurate

Kualitas Daging Se’i Sapi yang Diproses Menggunakan Buah Belimbing Wuluh (Averrhoa bilimbi Linn) Kering Matahari

Penelitian ini telah dilakukan untuk mengkaji penggunaan buah belimbing wuluh (Averrhoa bilimbi Linn) kering matahari terhadap kualitas daging se’i sapi. Metode yang digunakan adalah metode eksperimen dengan desain menggunakan Rancangan Acak Lengkap (RAL) faktorial yang terdiri dari 2 faktor pola 4x4 yang terdiri dari 4 faktor level pemberian buah belimbing wuluh kering matahari 0% (kontrol), 1,5%, 3%, 4,5% (w/w) dan 4 faktor lama penyimpanan 7 hari, 14 hari, 21 hari dan 28 hari. Kombinasi Kedua faktor ini menghasilkan 16 kombinasi setiap perlakuan terdiri atas 3 ulangan, dengan demikian akan diperoleh 48 unit. Parameter yang diukur dalam penelitian adalah pH, oksidasi lemak (TBA), aktivitas antioksidan, total plate count (TPC). Data analisis menggunakan Anova, apabila berpangaruh sangat nyata (P<0,01) dilakukan uji lanjut Duncan untuk mengetahui perbedaan diantara perlakuan dengan software SPSS 23. Hasil dari penelitian ini menunjukan bahwa interaksi antara faktor level buah belimbing wuluh kering matahari dan faktor lama penyimpanan berpengaruh nyata (P<0,05) terhadap pH, oksidasi lemak (TBA), aktivitas antioksidan, total plate count (TPC). Level pemberian buah belimbing wuluh kering matahari 4,5% memberikan hasil tertinggi pada aktivitas antioksidan, dan nilai terendah pada pH, oksidasi lemak (TBA) dan total plate count (TPC). Pada level 1,5% sampai 4,5% menekan laju oksidasi lemak (TBA) dan total plate count (TPC) pada setiap lama penyimpanan hari ke 7, 14, 21 dan 28, sebaliknya pada nilai aktivitas antioksidan cenderung meningkat seiring penambahan level buah belimbing kering matahari pada lama penyimpanan yang berbeda

The Effect of Giving Dragon Fruit Skin Extract (Hylocereus costarisensis) on the Quality of Se'i Beef Meat

This research has been conducted to determine the quality of processed meat mixed with dragon fruit skin extract (Hylocereus costarisensis) and determine the length of time of different watering. The method used was an experimental method with a design using a complete randomized design (CRD) consisting of 2 4x3 pattern factors consisting of 4 factors of dragon skin extract level of 0% (control), 40%, 60%, 80%, and 3 factors of duration time of watering 6 hours, 12 hours, 18 hours. Combining these two factors produces 12 combinations in each treatment and were repeated 3 times, thus there will be 36 experimental units. The parameters measured in the study were TBA, water activity, pH, total bacteria (TPC). Data analysis used Anova, if the impact is very significant (P<0.01) Duncan further test was conducted to determine the difference between treatment with SPSS 23 software. This study showed that the interaction between dragon fruit skin extract and the duration factor of watering had a very significant effect (P<0.01) on TBA, pH, TPC, antioxidant activity. The best combination for TBA, pH, TPC, antioxidant activity of meat se'i at 80% for 18 hours. While the activity of se'i water caused the Aw value to increase from 0.84 to 0.96, the best combination for the value of water activity meat se'i at the level of 60% with a length of 12 hours.

Solid-state diffusion reaction and formation of intermetallic compounds in the nickel-zirconium system

Chemical diffusion studies in the nickel-zirconium system are investigated in the temperature range of 1046 to 1213 K employing diffusion couples of pure nickel and pure zirconium. Electron microprobe and X-ray diffraction studies have been employed to investigate the formation of different compounds and to study their layer growth kinetics in the diffusion zone. It is observed that growth of each phase is controlled by the process of volume diffusion as the layer growth obeys the parabolic law. The activation energies for interdiffusion in NiZr and NiZr2, which are the dominant phases in the diffusion zone, are 119.0 &#177;13.4 and 103.0 &#177;25.0 kJ/ mole, respectively. The formation and stability of compounds over the temperature range have been discussed on the basis of existing thermodynamic and kinetic data

The Sensory Properties, Color, Microbial, Lipid Oxidation, and Residual Nitrite of Se’i Marinated with Lime and Roselle Calyces Extracts

Meat deterioration can occur because of lipid oxidation and bacteria that could affect meat quality. It has been recognized that fruits of lime (Citrus aurantifolia) and roselle (Hibiscus sabdariffa) calyces contain bioactive compounds that have a capability to prevent oxidation and bacterial growth. The objective of this research was to  investigate the effect of lime and roselle calyces extracts on se’i (Rotenese smoked beef) quality. Completely randomized design (CRD) with 2x4 factorial pattern was used in this study. The first factor (E) was source of extracts i.e., lime extract (E1) and roselle extract (E2). The second factor (L) was level of the extract consisted of 4 levels i.e., control (without extract/ L0); L1= 1%; L2= 2%; and L3= 3% (v/v). Each treatment consisted of 3 replications. Sensory properties measured were aroma, taste, and tenderness. Other variables measured were color, total plate count (TPC), thiobarbituric acid reactive substances (TBARS), and residual nitrite.  The taste and tenderness of se’i were affected (P&lt;0.05) by combination of the extract and the level of the extract.  Results showed that there were significant interactions (P&lt;0.05) between the kind of extracts and the level of extract on L (lightness), a (redness), and b (yellowness) values, TPC, TBARS, and residual nitrite values. The level of 3% of  lime extract as well as 3% of roselle calyces extract improved score of taste and tenderness, reduced a values, decreased TPC, TBARS, and residual nitrite values. Marinating in 3% of roselle calyces extract decreased the b value but marinating in 3% of lime increased the b value of se’i. It is concluded that marinating 3% of roselle or 3% of lime gives the best effect on taste, tenderness, TPC, and TBARS values of se’i