The influence of rotary valve distribution systems on the energetic efficiency of regenerative thermal oxidizers (RTO)

On–off valve systems, commonly used in regenerative thermal oxidizer (RTO) plants, generate, during the opening time, a mass flow rate (MFR) which is constant. On the contrary, rotary valve systems, which are increasingly adopted in RTO plants, are characterized by variable MFR profiles. In this work, the energy requirements of two RTO systems, equipped with on–off or rotary valves, were determined using a home‐developed numerical code. Energy performances were evaluated by calculating the thermal efficiency and pressure drop within structured or random packed bed RTO systems, at the same mean MFR. The results demonstrated that thermal efficiency was only moderately influenced by the valve system, and is slightly lower for the RTO with on–off valve. On the other hand, the study revealed that energy requirements of all RTO systems were basically unaffected by cycle duration, allowing valve rotational velocity to be freely set to maximize for other technical requirements. On the contrary, pressure drop was greatly influenced by the valve type and increased as variability in MFR function augmented. Moreover, the type of regenerator, structured or random packed bed, affected differently the total energy requirements (basically pumping energy plus auxiliary fuel). Energy requirements of structured and random regenerators were comparable only when volatile organic compounds concentration was lower than typical values encountered in the industrial practise. In other cases, structured regenerators RTO were more competitive. Finally, structured regenerators are usually the best choice when rotating valve distribution systems are adopted. Copyright © 2007 John Wiley & Sons, Ltd.     

Hydrophilic and hydrophobic copolymers of a polyaspartylhydrazide bearing positive charges as vector for gene therapy

BACKGROUND: The design of polymeric vectors for gene delivery provided with specific properties is one of the most critical aspects for a successful gene therapy. These polymers should be biocompatible as well as able to carry efficiently DNA to target tissues and to transfect it into cells. RESULTS: The formation of complexes of poly[(α,β‐asparthylhydrazide)–poly(ethylene glycol)] and poly[(α,β‐asparthylhydrazide)–hexadecylamine] copolymers functionalised with glycidyltrimethylammonium chloride (PAHy–PEG‐GTA and PAHy–C₁₆‐GTA, respectively) with DNA was studied. The effects of the introduction of hydrophilic (PEG) or hydrophobic (C₁₆) moieties on the chains of PAHy–GTA copolymers, such as the stabilising effect on the DNA structure, were evaluated. In particular, we observed a high DNA protection by PAHy–PEG‐GTA copolymers. Degradation studies led us to suppose a particular aqueous conformation of the polyionic complex of PAHy–PEG₂₀₀₀‐GTA in which DNA should be internalised into an inner core surrounded by a PEG hydrophilic shell; while no significant protection was detected with PAHy–C₁₆‐GTA in which DNA should be disposed on the surface of the complex, freely exposed to DNase II action. CONCLUSION: The insertion of PEG or C₁₆ chains into the polymeric structure of PAHy–GTA copolymers changes significantly the DNA complexing and protecting ability of the PAHy–GTA copolymers, showing that hydrophilic and hydrophobic side chains can play a crucial role in supramolecular arrangements of interpolyelectrolyte complexes between DNA and PAHy copolymers. Copyright © 2008 Society of Chemical Industry     

Spread-Spectrum Code Acquisition in the Presence of Cell Correlation

A new special function, called the modified generalized Q (MGQ) function, is here defined to analytically express the performance of the pseudonoise code acquisition based on matched filter correlators. In the considered case of two cells per chip, no convergent infinite series have been found in the open literature expressing the probabilities of false alarm and detection. The performance is analyzed in terms of mean acquisition time for signal-to-noise ratios of practical interest     

Intensity-ratio and color-ratio thin-filament pyrometry: Uncertainties and accuracy

Thin-filament pyrometry (TFP) has been proven to be a useful approach to measure flame temperature. It involves placing a thin filament (SiC fiber typically) in hot gases and inferring the gas temperature from the radiance of the glowing filament. The TFP approach offers simplicity and low cost, and it is useful in situations where other techniques are difficult to apply, such as high-pressure environments. In this paper, some recent developments of TFP are discussed. The physical backgrounds of two TFP approaches, namely the intensity-ratio approach and the color-ratio approach, are reviewed along with the required radiation correction. Several sources of error, such as the fiber aging behavior (fiber properties varying with time), spectral emissivity and calibration, have been investigated. Measurements in well-calibrated laminar flames show very good agreement with reference temperatures based on N₂ coherent anti-Stokes Raman scattering (CARS) measurements. Uncertainty analysis has also been performed and provides insights on improving TFP measurement accuracy.     

Engineering Design Study on an Innovative Hydrokinetic Turbine with on Shore Foundation

Tidal currents are a resource of great potentiality and not yet fully explored. Several efforts have been made to exploit these resources, but the costs associated to the deployment of tidal plants in marine environments are usually too high. The aim of this work is to present a system able to handle with the above mentioned problems, through the development of a particular hydrokinetic turbine design. In previous works, the authors described a basic turbine configuration achieving interesting performances, although some operational inconveniences were detected. Those problems have been existing so the solution should be optimized and redesigned. As a result, a new design of the turbine is proposed, consisting of a double rotor spinning in opposite directions in order to balance the induced mechanical torque. From preliminary evaluations related to the Messina Strait tidal cycles （Punta Pezzo site, RC, Italy）, a single 12 m diameter turbine can supply a power of about 500 kW with a peak current speed of 3 m/s and deliver up to 450 MWh/year.     

Selective Manipulation of Discrete Mannosidase Activities in the Endoplasmic Reticulum by Using Reciprocally Selective Inhibitors

Within the endoplasmic reticulum, immature glycoproteins are sorted into secretion and degradation pathways through the sequential trimming of mannose residues from Man₉GlcNAc₂ to Man₅GlcNAc₂ by the combined actions of assorted α‐1,2‐mannosidases. It has been speculated that specific glycoforms encode signals for secretion and degradation. However, it is unclear whether the specific signal glycoforms are produced by random mannosidase action or are produced regioselectively in a sequenced manner by specific α‐1,2‐mannosidases. Here, we report the identification of a set of selective mannosidase inhibitors and development of conditions for their use that enable production of distinct pools of Man₈GlcNAc₂ isomers from a structurally defined synthetic Man₉GlcNAc₂ substrate in an endoplasmic reticulum fraction. Glycan processing analysis with these inhibitors provides the first biochemical evidence for selective production of the signal glycoforms contributing to traffic control in glycoprotein quality control.     

Fast magnetic field computation in fusion technology using GPU technology

One of the main issues in the simulation of Tokamaks functioning is the reliable and accurate computation of actual field maps in the plasma chamber. In this paper a tool able to accurately compute magnetic field maps produced by active coils of any 3D shape, wound with high number of conductors, is presented. Under linearity assumption, the coil winding is modeled by means of “sticks”, following each conductor's shape, and the contribution of each stick is computed using high speed Graphic Computing Units (GPU's). Relevant speed enhancements with respect to standard parallel computing environment are achieved in this way.     

All-optical Integrated Nonlinear Devices

Abstract

The field of third-order nonlinear integrated optics is reviewed, with emphasis on intensity-dependent phenomena for all-optical device applications. The most relevant material issues are briefly summarized.