Analyses and techniques for phase noise reduction in CMOS Colpitts oscillator topology

This paper reports the analyses of three techniques for phase noise reduction in the complementary metal‐oxide semiconductor (CMOS) Colpitts oscillator circuit topology. Namely, the three techniques are inductive degeneration, noise filter, and optimum current density. The design of the circuit topology is carried out in 28‐nm bulk CMOS technology. The analytical expression of the oscillation frequency is derived and validated through circuit simulations. Moreover, the theoretical analyses of the three techniques are carried out and verified by means of circuit simulations within a commercial design environment. The results obtained for the inductive degeneration and noise filter show the existence of an optimum inductance for minimum phase noise. The results obtained for the optimum bias current density technique applied to a Colpitts oscillator circuit topology incorporating either inductive degeneration or noise filter show the existence of an optimum bias current density for minimum phase noise. Overall, the analyses show that the adoption of these techniques may lead to a potential phase noise reduction up to 19 dB at a 1‐MHz frequency offset for an oscillation frequency of 10 GHz. © 2015 The Authors International Journal of Circuit Theory and Applications Published by John Wiley & Sons Ltd.     

Analysis of seismically-isolated two-block systems using a multi–rocking-body dynamic model

A novel multibody rocking model is developed to investigate the dynamic response of two stacked rigid blocks placed on a linear base isolation device. The model is used to investigate the dynamic response of a realistic statue-pedestal system subject to pulse-like ground motions. The analysis shows that, in general, base isolation increases the safety level of the rocking system. However, for large period pulses or small size blocks, the isolator can amplify the ground motion, resulting in a lower minimum overturning acceleration than for the nonisolated system. Further, the amplification or shock spectrum of a linear mass-dashpot-spring oscillator, was found to be the reciprocal of the minimum nondimensional overturning acceleration of the investigated rocking system. Novel rocking spectra are obtained by normalizing the frequency of the pulse by the frequency of the isolator. The analysis also demonstrates how the dynamic response of the two stacked blocks is equivalent to that of a single-block configuration coincident with the whole system assumed monolithic or the upper block alone, whichever is more slender.     

Reverse osmosis and nanofiltration membranes for the improvement of must quality

When the vintage is poor, different must concentration techniques are used for overcoming grape compositional deficiency, such as evaporative or freeze concentration, and membrane processes. The membrane filtration works at low temperature, preserving must components from degradation. The aim of the present work was to tailor reverse osmosis and nanofiltration technologies applied to grape juice testing several membranes for different grape varieties from southern Italy. The main oenological parameters, including sugar content, acidity, pH, color and total phenol content, were evaluated in comparison with the addition of rectified concentrated must. Quality characteristics of all musts showed to be improved by means of membrane processes, which could be successfully implemented in the cases of premature harvest carried out for obtaining wines with enhanced acidity.     

New gas concentration measurement system for the PANDA containment test facility

The increased use of computational fluid dynamics code for analysis and design purposes demands high quality experimental data to validate the simulation codes. Experimental data of fluid stratification and stratification break-up phenomena are generated in the frame of OECD/SETH-2 project at the PANDA facility. A new gas concentration measurement system is presented that is based on speed of sound measurements. Speed of sound in gas mixtures is a unique function of the temperature and the fractions of the components and therefore can be used to compute the fractions in varying compositions. The speed of sound is measured indirectly measuring the time of flight of an ultrasound pulse between two ultrasound transducers. The 30 transducers employed proved to be able to withstand the unfavorable conditions inside the facility with temperatures of up to 110 °C and steam that may condense. A frame rate (1 frame = each transducer has been excited) of 1.6 Hz and a helium fraction resolution of 1.5% in steam are achieved.     

An adaptive strategy for Li-ion battery internal state estimation

Further developing a study presented in Di Domenico, Prada, and Creff (2011), this paper presents an extended Kalman filter (EKF) based on an electro-thermal model for the estimation of the internal state of a lithium-ion battery, i.e. state of charge and the cell overpotential. In order to compensate for uncertainties in the model parameters and in the measurements, it is first shown that the filter robustness strongly depends on the State of Charge (SOC) range. Then the filter weights are adapted according to the estimated SOC value. This estimation technique is tested using experimental data collected from a commercial A123 Systems lithium iron phosphate/graphite (LiFePO₄/graphite) cell. The filter shows good performance. The estimation of SOC exhibits an average error within 3% range and the overpotential is estimated with a precision higher than 5 mV.     

Internet Protocol Packet Delay Variation measurements in communication networks: How to evaluate measurement uncertainty?

Measurement of Quality of Service (QoS) parameters is a relevant task in communication networks. Similarly to other contexts, the measurement result has to be completed with the related uncertainty in order to provide information about the significance and reliability of the overall measurement process. This aspect is particularly crucial in communication networks. In fact, the measured values of QoS parameters have often to be compared against suitable thresholds to check their compliance with required quality constraints (QoS levels delivered to the user are generally offered for a fee) or to reliably verify the effect of new services conveyed by the network on its performance.     

New-generation of cryogenic sapphire microwave oscillators for space, metrology, and scientific applications

This article reports on the characterization of cryogenic sapphire oscillators (CSOs), and on the first test of a CSO in a real field installation, where ultimate frequency stability and continuous operation are critical issues, with no survey. Thanks to low-vibration liquid-He cryocooler design, Internet monitoring, and a significant effort of engineering, these oscillators could bridge the gap from an experiment to a fully reliable machine. The cryocooler needs scheduled maintenance every 2 years, which is usual for these devices. The direct comparison of two CSOs demonstrates a frequency stability of 5 × 10(-16) for 30 s ≤ τ ≤ 300 s integration time, and 4.5 × 10(-15) at 1 day (1 × 10(-14) typical). Two prototypes are fully operational, codenamed ELISA and ULISS. ELISA has been permanently installed the new deep space antenna station of the European Space Agency in Malargu?e, Argentina, in May 2012. ULISS is a transportable version of ELISA, modified to fit in a small van (8.5 m(2) footprint). Installation requires a few hours manpower and 1 day of operation to attain full stability. ULISS, intended for off-site experiments and as a technology demonstrator, and has successfully completed two long-distance travels.     

Bibliometric positioning of scientific manufacturing journals: a comparative analysis

This article analyzes some of the most popular scientific journals in the Manufacturing field from the point of view of four bibliometric indicators: the ISI impact factor (ISI-IF), the Hirsch (h) index-for-journal, the total number of citations and the h-spectrum. h-spectrum is a novel tool based on h, making it possible to (i) identify a reference profile of the typical authors of a journal, (ii) compare different journals and (iii) provide a rough indication of their ??bibliometric positioning?? in the scientific community. Results of this analysis can be helpful for guiding potential authors and members of the scientific community in the Manufacturing area. Of particular interest is the construction of maps based on h-spectrum and ISI-IF to compare journals and monitor their bibliometric positioning over time. A large amount of empirical data are presented and discussed.     

Original article: Innovation in fig syrup production process: a rheological approach

An engineering approach, based on rheological characterisation, to the analysis of a food process for fruit syrup production is presented in this paper. The process has been investigated to analyse the effects of selected operating parameters on the product rheology to design materials having mechanical properties suitable for specific applications. Process conditions have been changed either adding alkaline salts, as pH modifiers to improve pectin extraction efficiency, or decreasing operative temperature, reducing thermal damage of the material. It has been found that alkaline salt addition yields structured products because of the improved efficiency of pectin extraction and to the enhancement of the gelation phenomena. Mild conditions during either extraction or concentration lead to a more structured syrup, whereas more drastic operations bring to liquid‐like products. The proposed approach, based on the analysis of rheological properties, may support the design of new products having controlled properties and may reduce the effect of raw material variability onto the product quality.     

Confocal Raman imaging,FTIR spectroscopy and kinetic modelling of the zinc oxide/stearic acid reaction in a vulcanizing rubber

The reaction of zinc oxide (ZnO) with stearic acid (StA) to form zinc stearate (ZnSt) has been investigated experimentally in a model matrix (unvulcanized styrene–butadiene rubber) by using confocal Raman microscopy and FTIR transmission spectroscopy. The heterogeneous nature of the reacting system has been confirmed. The Raman analysis has revealed the core–shell structure of the product, which is formed via the gradual shrinkage of the ZnO core and the concurrent formation of a surrounding ZnSt shell of increasing thickness. FTIR spectroscopy has provided information about the molecular state of aggregation of StA when dissolved in the rubber, as well as quantitative information on the reaction kinetics. The kinetic behaviour of the system has been interpreted using a semi-quantitative heterogeneous reaction model grounded on the Raman imaging results, which was able to catch the essential features of the phenomenon and to simulate reliably the experimental conversion vs time data at three different temperatures.