An automatic calibrator for wattmeters with harmonic analysis capability

This paper deals with a three-phase phantom-power generator, which is designed for calibrating digital wattmeters with harmonic analysis capability. The calibration of such instruments is a critical task due to the lack of suitable calibrators. Fortunately, the calibration procedure can be limited to the first harmonic components when digital wattmeters are employed to characterise electrical machines, so that also simple calibrator design can be adopted. This paper describes a three-phase calibrator arrangement which is able to generate an arbitrary spectrum up to 5 kHz and a phantom power variable up to 3 kVA per phase. The uncertainty on the power associated to the first harmonic components is of about 0.1% in nonsinusoidal conditions. The calibrator employs a Direct Digital Synthesis technique, so that a frequency change of the output signal can be obtained without modifying the sampling frequency. Such a technique also permits to generate the frequency modulated signals that are often encountered at the output of static power converters that feed electrical machines.     

Handheld-impedance-measurement system with seven-decade capability and potentiostatic function

This paper describes design and test of a new impedance-measurement system for nonlinear devices that exhibits a seven-decade range and works down to a frequency of 0.01 Hz. The system is specifically designed for electrochemical measurements, but the proposed architecture can be employed in many other fields where flexible signal generation and analysis are required. The system employs an unconventional signal generator based on two pulsewidth modulation (PWM) oscillators and an autocalibration system that allows uncertainties of less than 3% to be obtained over a range of 1 k/spl Omega/ to 100 G/spl Omega/. A synchronous demodulation processing allows the noise superimposed to the low-amplitude input signals to be made negligible.     

Virtual environment for fast development of distributed measurement applications

This paper deals with a virtual environment that allows automatic measurement systems to be easily developed by accessing programmable instrumentation, which can be located either in a local or in a remote laboratory. The environment, which is based on a client-server application that runs on a single personal computer or over the Internet, is designed to hide most of the details connected to the setup of a complex measurement system to the users. Client and server applications have been developed in Java/spl trade/ language so that they can be used on different platforms and are easily extensible to accommodate new processing tasks, interfaces, and instruments.     

Autochthonous white grape pomaces as bioactive source for functional jams

Seeds and skins from grape pomaces of Pecorello and Mantonico cv underwent extraction (ultrasound–assisted or maceration), in order to obtain added-value ingredients for the production of a functional pear jam. The antioxidant features of the extracts were tested by in vitro colorimetric assays. Among seeds, Mantonico by maceration (MSC) showed the best results, as well as Mantonico by ultrasound-assisted extraction (MBs) among skin extracts. The selected extracts were fully characterised by NMR and MS techniques, confirming the presence of many polyphenols, flavonoids and tannins among others. Pectin was then derivatised by the grafting procedure with the active molecules of MBs and MSC. The latter produced the best antioxidant polymer also without toxicity evaluated using Caco-2 cells and was used for the jam preparation. The functional pear jam showed improved antioxidant performances in comparison with its non-functional counterparts as well as its maintenance over time (15 days).     

Interconnected power systems laboratory: a computer automatedinstructional facility for power system experiments

This paper presents a unique facility capable of exhibiting the operation of modern day power system energy management systems (EMS). The purpose is educational with possible research applications. We present the design and construction of the laboratory facility. Key elements of the facility include a real-life, flexible power system network, signal conditioning hardware, data acquisition (DAQ) equipment, and client/server industry standard computer networking technology. The designed EMS system will allow students to get experience on the realistic operation and control of power systems and expose students to modern supervisory control and data acquisition (SCADA) equipment and procedures used by the power industry     

Image makers of British modernism: Dell & Wainwright at The Architectural Review

‘It used to be unkindly said of the modern school of architects before the war that they designed their buildings not to please clients or even themselves, but to please Dell & Wainwright. Unfair though this was, it paid a deserved compliment to Dell &Wainwright, the official photographers of The Architectural Review. It meant that their representations of modern buildings—resplendent in a perpetual mellow sunshine, beautifully composed within a frame of leafy branches or above a foreground dappled with shadows—when reproduced on the glossy pages of the Review came near to the ideal their designers had in their imaginations. They were the brave new world itself?…’ This comment, published in the 13^th June, 1946, Issue of the Architects’ Journal on the occasion of Mark O. Dell’s retirement, highlights both the expressive power and the influential nature of Dell & Wainwright’s photography. Their images were part of the Review’s 1930s campaign to promote modern architecture in Britain and given much prominence in the periodical’s pages, which had been reshaped by the Editor Hubert de Cronin Hastings and his team thanks to the use of experimental typography and innovative layouts. Many of the trademark features of Dell & Wainwright’s work had been introduced in architectural imagery by the ‘New Photography’, which had originated in continental Europe in the previous decade and encompassed both the ‘New Vision’ of Moholy-Nagy and Rodchenko, and the ‘New Objectivity’ of photographers such as Werner Mantz and Albert Renger-Patzsch. This paper examines the origins of Dell and Wainwright's partnership, their work for The Architectural Review and its critical reception, but also questions some of the most recurrent assumptions related to their photographic output, which was decidedly wider in range than is commonly believed.     

An audio card-based kit for educational purposes

This paper describes an inexpensive kit which is designed to allow users to get acquainted with modern instrumentation without the necessity to get to a laboratory where the instruments are available. The kit takes advantage of any low-cost audio card installed into a personal computer and is based on an open-source code, which interacts with the audio card, and on a simple test board, which allows the audio card to be calibrated. The kit is the base of the Instrumentation Training Project at the Politecnico di Torino, which is composed of a set of guided experiments based on the capabilities of the training kit.     

Individual differences in working memory and comprehension: A test of four hypotheses.

A relationship has consistently been found between measures of working memory and reading comprehension. Four hypotheses for this relationship were tested in 3 experiments. In the 1st 2 experiments, a moving window procedure was used to present the operation–word and reading span tasks. High- and low-span Ss did not differentially trade off time on the elements of the tasks and the to-be-remembered word. Furthermore, the correlation between span and comprehension was undiminished when the viewing times were partialed out. Exp 3 compared a traditional experimenter-paced simple word-span and an S-paced span in their relationship with comprehension. The experimenter-paced word-span correlated with comprehension, but the S-paced span did not. The results of all 3 experiments support a general capacity explanation for the relationship between working memory and comprehension. (PsycINFO Database Record (c) 2010 APA, all rights reserved)