Cross‐Coupled Ratio Control Structure

Abstract

In this paper, a cross‐coupled ratio control structure with two blend stations has been proposed. The main feature of the proposed structure is to give a good ratio performance for both set‐point changes and load disturbances that might occur in any one of the two loops. A simple tuning procedure for the inner controllers of the two loops and an easy design methodology for the blend stations have been proposed in order to avoid any significant tuning and design effort for the implementer. The proposed structure is realized on a microcontroller based system. This cross‐coupled ratio control structure that has been embedded into the microcontroller is then used to maintain the prescribed ratio “a” of the two processes, namely heat transfer process trainer (PT 326‐Feedback) and process control simulator (PCS 327‐Feedback). The same two processes are run under another alternative ratio control structure and the results are compared with each other.     

Evolution equations for nonlinear waves in a tapered elastic tube filled with a viscous fluid

In this work, employing the reductive perturbation method and treating the arteries as a tapered, thin walled, long and circularly conical prestressed elastic tube, the propagation of weakly nonlinear waves is investigated in such a fluid-filled elastic tube. By considering the blood as an incompressible viscous fluid, depending on the viscosity and perturbation parameters we obtained various evolution equations as the extended Korteweg-de Vries (KdV), extended KdV Burgers and extended perturbed KdV equations. Progressive wave solutions to these evolution equations are obtained and it is observed that the wave speeds increase with the distance for negative tapering while they decrease for positive tapering.     

Effects of ochratoxin A on micronucleus frequency in human lymphocytes

Ochratoxin A (OTA), a nephrotoxic and carcinogenic mycotoxin, was investigated to examine its potency to induce micronuclei (MN) in cultured human lymphocytes. Lymphocyte cultures were treated for the last 48 h with OTA at concentrations of 25 microM, 10 microM, 1 microM, 100 nM, 10 nM, 1 nM, and 100 microM and absolute ethanol. At the highest concentration, OTA was found to induce MN in cytokinesis-blocked lymphocytes (p < 0.05). The 25 microM OTA concentration also led to a clear decrease in the percentage of binucleated cells, probably due to cytotoxicity. OTA at the other concentrations tested did not induce MN frequency. These results indicate that a high concentration of OTA is genotoxic in cultured human lymphocytes.     

Genetic divergence in cellular resistance to heat shock in cattle: differences between breeds developed in temperate versus hot climates in responses of preimplantation embryos,reproductive tract tissues and lymphocytes to increased culture temperatures

The detrimental effects of heat stress on fertility in cattle are less pronounced in heat-tolerant breeds. Although these genetic differences reflect differences in thermoregulation, cells from heat-tolerant breeds are less adversely compromised by increased temperature (that is, heat shock) than cells from heat-sensitive breeds. Experiments were performed to test the hypothesis that cells and tissues from two thermotolerant breeds (Brahman and Senepol) are better able to survive and function after exposure to increased temperature than cells and tissues from two thermosensitive breeds (Holstein and Angus). Exposure of embryos at>eight-cell stage at day 5 after insemination to heat shock of 41.0 degrees C for 6 h decreased development to the blastocyst stage and the number of cells per embryo. However, the deleterious effect of heat shock on blastocyst formation and the number of cells per embryo was less pronounced for Brahman than for Holstein and Angus breeds. Embryos from Senepol cows had very low development and it was not possible to determine heat shock effects in this breed. In contrast to the sensitivity of embryos to heat shock, there was no effect of a 41.0 degrees C heat shock on [(3)H]leucine incorporation into proteins secreted by oviductal or endometrial explants. Lymphocytes from Brahman and Senepol cows were more resistant to heat-induced apoptosis than lymphocytes from other breeds. Heat shock reduced lymphocyte glutathione content but the magnitude of the decrease was not affected by breed. In conclusion, embryos from Brahman cows are more resistant to heat shock than embryos from Holstein or Angus cows. Genetic differences are also present in thermotolerance for apoptosis response in lymphocytes, with Brahman and Senepol cattle being more resistant to heat shock than Angus and Holstein breeds. It is likely that the evolutionary forces that led to the Brahman and Senepol breeds being adapted to hot climates resulted in the selection of genes controlling resistance to cellular heat shock.     

Effect of Some Transition Metals on the Monolayer Oxidation of Methyl Linoleate

Methyl linoleate was deposited as a monolayer on a silica gel control and on silica gel supplemented with double or quadruple the control’s amount of the transition metal ions (TMI) iron, copper, vanadium or titanium. The treatments were oxidized at 25 °C, and periodically samples were examined for peroxide values (PV) and by gas chromatography for oxidation products (GC). Comparison of the treatments revealed that: Surface oxidation on silica gel owes its high rate to TMI, which may speed free radical initiation. Epoxidation is catalyzed by the presence of vanadium and titanium. Scission products (SP) and unrecovered mass increased with the extent of oxidation probably because of increased free radical life time.     

Optical and physical behaviours of newly developed germanium-tellurium (GeTe) glasses: a comprehensive experimental and in-silico study with commercial glasses and ordinary shields

Journal of Materials Science: Materials in Electronics - In this study, synthesis and determination of physical, optical, and radiation shielding properties of glasses based on TeO2 and GeO2 were...     

Investigation of temperature,thermodynamic parameters and dielectrical properties of poly(vinylimidazole)–Na–bentonite nanocomposite

The adsorption of poly(vinylimidazole) (PVI) onto Na–Bentonite from aqueous solutions has been investigated as a function of temperature. According to the experimental results, the adsorption of PVI decreases with temperature from 25 to 55°C. The study of temperature effect has been quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes. The electrical and dielectrical properties of PVI–Na–Bentonite composite have been investigated. The current‐voltage studies show that conductivity was increased at T = 25°C. The dc conductivity was calculated at T = 25°C. The samples show typical dielectric behavior from capacitive measurements. Depending on maximum interactions at 25°C, ac conductivity and loss factors are also in high values. Especially, at frequencies over 1.5 kHz, it was seen completely clay behavior. Variation of tangent loss factor‐frequency shows decreasing of polarization density in structure in high frequency. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Spectroscopic and thermal analysis of lead-free multipurpose radiation shielding glasses

The genetic algorithm was used to identify glasses, of the composition 50Bi₂O₃-(50-x) B₂O₃-xBaO with $25\ge x\ge 5$ wt%, that have a similar half-value layer (HVL) and neutron removal cross-section. The structure of these glasses was further explored using a combination of spectroscopic and thermal analysis in order to ascertain whether they possess advantageous physical properties comparable to traditional materials used in nuclear reactor design. Differential scanning calorimetry (DSC) analysis was used to examine the thermal profile of the glass system and to identify glass transition temperature T_g and softening temperature T_s. Glass of the composition 50Bi₂O₃–30B₂O₃–20BaO had exhibited the highest thermal stability. Analysis of the Raman spectra of the samples confirmed the presence of BiO₆ octahedrons and B-O-B bonds in poly borate chains. A deconvolution of the IR spectra was carried out to determine the relative proportions of BO₃ triangles to BO₄ tetrahedral units in the glass network that would affect the density and bulk modulus. Optical absorption spectrum of the samples exhibited absorption peaks in the blue region along with a broad band of absorption at longer red wavelengths associated with excitation of bismuth ions. When compared to traditional heavy concretes used in radiation shielding, the bismuth-barium borate glasses exhibited superior performance over conventional barite concrete as a gamma-radiation shield and was comparable to limonite concrete as a neutron radiation shield. The bulk modulus of the glass series was also found to be comparable to that of regular concrete at approximately to 30?GPa.