Analytical theory for an approach calculation of non-balanced composite box beams

For aeroelastic problems, optimization of the behavior of box beams, carried out in composite materials, can lead to the construction of structures whose longitudinal axis is not necessarily the orthotropic axis of the materials. These beams present couplings such as Flexion–Torsion or Traction–Torsion. In this study, we propose an analytical theory which allows these structures to be dimensioned with extreme accuracy and without using complicated calculations. The method developed, based on a weak hypothesis on the field of deformations, makes it possible to obtain from simple analytical calculations, the stresses and displacement in a cross-section for normal load , flexion moments and torsion moments . It is then possible using the laminated plates theory, to determine the stresses in each layer. The results obtained correspond perfectly to those found in a 3D Finite Element model, calculated using CATIA–ELFINI software. On the central part of the beams, the relative differences noticed between these two methods on the calculation of stress, strain and rigidities are negligible. Near the embedded section, warping is very important and the relative error is great.     

Design, Analysis and Experimental Testing of BPSK Homodyne Receivers Based on Subcarrier Optical Phase-Locked Loop

The analysis of a subcarrier optical phase-locked loop (SC-OPLL) is carried out in order to optimize phase-locking performance. A new parameters optimization procedure, useful for OPLL design, is demonstrated theoretically and experimentally. An SC-OPLL based on this procedure has been realized, so a pilot carrier SC-OPLL and a nonlinear SC-OPLL optical receiver have been experimentally constructed and tested. An 8B/10B line coding is employed for pilot carrier SC-OPLL receiver in order to improve performance and a new architecture of decision-driven PLL is experimentally demonstrated.     

Software for personal instruments

When a personal computer (PC) is used as the computing system of an intelligent instrument, software devoted to measurement process control and to measurement process outputting can be specially developed to assist the operator throughout the measurement process in a friendly way. When these conditions are met, the intelligent instrument is called a personal instrument (PI). The main features of a PI are discussed, and the requirements for PI software are given. The performance of an original software package for PI is illustrated, showing how all the requirements are satisfied. This software, coupled to a good commercial data acquisition system, features high-precision measurement and a high level of friendliness and can be useful for lab tests and educational purposes. For lab tests, this software is a good basis for an automatic test station with extended help facilities. It ensures better performances than that of a digital scope because it allows dedicated measurement routines to be developed and executed. The software is effective for educational applications, since it allows direct application of all capabilities offered by computers in instrumentation, when associated with suitable A/D (analog/digital) conversion hardware     

LYS2 gene and its mutation in Kluyveromyces lactis

The KlLYS2 gene, encoding the alpha-aminoadipate reductase of Kluyveromyces lactis, was isolated by complementation of a lysA1 mutant. The deduced amino acid sequence shared an identity of 73% with the LYS2 product of Saccharomyces cerevisiae. Despite the high sequence homology of the alpha-aminoadipate reductase genes, the two yeast species differently responded to the presence of alpha-aminoadipate in the medium. Wild-type S. cerevisiae is known to be sensitive to alpha-aminoadipate, but becomes resistant when mutated to lys2. In contrast, K. lactis strains were found to be naturally resistant to alpha-aminoadipate. Therefore, the positive selection procedure for the isolation of lys2 mutants on alpha-aminoadipate, as practised in S. cerevisiae, cannot be applied to K. lactis. A possible reason of this difference may be that the catalytic rate of the alpha-aminoadipate reductase differs in the two yeasts. The EMBL/Genbank Accession No. for the KlLYS2 gene is AJ504405.     

RAG1 and RAG2: nuclear genes involved in the dependence/independence on mitochondrial respiratory function for growth on sugars

The analysis of five independent isolates of Kluyveromyces lactis shows that CBS 2359, CBS 683 and CBS 4574 could grow in the presence of mitochondrial inhibitors (antimycin A, oligomycin or erythromycin) and that CBS 2360 and CBS 141 were unable to grow in the presence of drugs. The resistant growth was observed only on glucose and not on other fermentable carbon sources (galactose, lactose). The phenotype 'growth on glucose in the presence of mitochondrial inhibitors' was called Rag+. This phenotype was found to be controlled by two unlinked nuclear genes: RAG1 and RAG2. Either of their recessive alleles, rag1 and rag2, led to the Rag- phenotype (i.e. the failure of growth on glucose in the presence of antimitochondrial drugs). Rag- strains represent the case in which fermentative growth becomes absolutely dependent on the functioning of the normal respiratory chain.     

Effect of modified celluloses on dough rheology and microstructure

The effect of different modified celluloses on dough microstructure and rheological characteristics was studied. Microcrystalline cellulose (MCC), carboxymethylcellulose (CMC) and two different types of hydroxypropylmethylcellulose (HPMC F4M and HPMC F50) were tested in a range of concentration from 0.25% to 1.5% (flour basis). Doughs were formulated without and with salt (2%w/w flour basis). Farinographic water absorption increased when hydrocolloids were incorporated and the highest values were obtained in mixtures without NaCl and when HPMCs were added. A linear relationship between the percentage increment in water absorption and the hydrocolloid level was observed within the assayed range of concentrations. The development time was markedly increased when CMC was added. CMC and HPMC did affect or not dough stability depending on the presence or absence of salt whereas the stability was not modified by MCC. Texture attributes and the rheometric parameter tan δ were analyzed through Principal Component Analysis (PCA). Two factors described the 88.9% of total variation, one of them composed by hardness, consistency, adhesiveness and tan δ and the other composed by resilience and cohesiveness. Hydrocolloids addition softened the dough, particularly when salt was absent. Samples with salt and with hydrocolloids exhibited more cohesive and less resilient characteristics. Rheological results were in agreement with the characteristics of gluten network studied by SEM since a diminished stability and softer dough could be associated with a more disrupted matrix.     

A Comprehensive Mixed-Mode Time-Domain Load- and Source-Pull Measurement System

We present a novel test set devised for nonlinear balanced device characterization using load-pull techniques. The system is capable of measuring the voltage and current waveforms at the calibration reference planes while independently tuning the device under test (DUT) source and load differential- and common-mode terminations. The test set is designed to address present and future large-signal multiport measurement needs, easing the characterization task while developing new multiport active devices.      

A digital method for the identification of the source of distortionin electric power systems

The presence of distortion in voltages and currents in the electric power systems causes many inconveniences, ranging from an increment in the line loss to the irradiation of disturbances. The correct identification of the source of distortion is important for attaining an effective compensation of the nonactive components of power. This paper refers to a method, based on the evaluation of the sign of the harmonic active powers, originally designed for identification of the source of harmonic distortion in three-phase systems. An application of this method to the development of a new instrument is described. The instrument accuracy and the results of some experimental work are discussed     

A virtual instrument for the measurement of the characteristics ofmagnetic materials

A completely digital method for the fast and accurate measurement of the magnetic behavior (such as the magnetization curve, the hysteresis loop, and the total loss) of magnetic materials under cyclic magnetization is presented. The mathematical basis of this method is discussed and used to develop a virtual instrument dedicated to the determination of the magnetic behavior. The experimental results for ferrosilicon plats and amorphous materials are reported, and the accuracy and sensitivity of the technique are discussed     

A low-cost frequency multiplier for synchronous sampling ofperiodic signals

The theory of digital signal processing indicates clearly that the measurements performed on periodic signals by means of digital techniques are affected by an error due to the nonsynchronization between the sampling frequency and the signal frequency. The authors present a low-cost device, based on a frequency multiplier, that allows the generation of sampling pulses synchronized with the signal frequency. The behavior of this device is analyzed in order to assure its ability to work with input signals in the frequency range typical of the mains. As an example of the application of this device, the results of the Fourier analysis of a multifrequency signal are given, showing the high accuracy that can be attained