Vibration modes and acoustic noise in a four-phase switchedreluctance motor

Acoustic noise in the switched reluctance motor (SRM) is caused primarily by the deformation of the stator lamination stack. Acoustic noise is most severe when the periodic excitation of the SRM phases excites a natural vibration mode of the stack. The natural vibration modes and frequencies of a four-phase, 8/6 SRM are examined. Structural finite element analysis is used to compute the natural modes and frequencies. Impulse tests on the stator stack verify the calculations and show which modes are excited. Heuristic arguments are developed to predict the operating conditions that will excite the natural modes. Measurement of vibration while the machine is under load shows which operating conditions excite the natural modes and verifies the predictions. An approximate formula is derived to predict the frequency of the fundamental vibration mode in terms of lamination dimensions and material properties. The formula is validated by comparison with finite element calculations for several laminations, and hence is shown to be useful in design trade-off studies     

High-performance integrated Fresnel lenses on oxidised silicon substrate

We report, to our knowledge for the first time, the achievement of analogue integrated Fresnel lenses having very high performances, and the association of two such lenses. Focusing efficiencies higher than 60% have been measured on that component with a background noise lower than ?27 dB at 1° off-axis in the focal line.     

Space-frequency block code for single-carrier FDMA

A full-diversity space-frequency block code (SFBC) for single-carrier frequency-division multiple access (SC-FDMA) systems is presented. The code is designed for two transmit antennas and preserves the low envelope fluctuations of SC signals. The good performance of the proposed scheme over multiple-input multiple-output (MIMO) channels, both in static and in high-speed mobility scenarios, is proved.     

Integrated optical spectrum analyser using planar technology on oxidised silicon substrate

We report, for the first time, the achievement of an integrated optical spectrum analyser on oxidised silicon substrate. This device uses an entire planar technology fully compatible with microelectronic processes.     

Integration of an electrooptic polymer in an integrated opticscircuit on silicon

This paper presents the joining of active nonlinear polymer waveguides with passive silicon nitride waveguides (SiO₂-Si ₃N₄-SiO₂) to form an integrated Mach-Zehnder modulator with a lateral electrode configuration on a silicon substrate. Passive and active waveguides are based on a silicon-nitride-strip guiding structure. In the active waveguide a nonlinear polymer layer is used to obtain an index modulation via the electrooptic effect. Despite the silicon nitride strip based guiding structure, 63% of the energy of the fundamental mode is guided in the nonlinear polymer (provided by Flamel Technology, Venissieux, France). Poling with field strengths up to 75 V/μm applied to the lateral electrodes has been employed to orient the chromophores. A half wave voltage of 35 V has been measured for an electrooptic coefficient of 5.8 pm/V at a wavelength of 1.3 μm. Optical loss measurements have been done on polymer and passive waveguides. The best results have been 1.8 dB/cm for the active and 0.78 dB/cm for the passive waveguides leading to a total loss of 6 dB for a modulator with an interaction length of 2.5 cm. The coupling loss between a laser diode and the passive waveguide structure was measured to be at least 4.6 dB using a microscope objective and piezo-electric displacement elements. Stability tests under atmospheric conditions have shown a decrease of the electrooptic coefficient which might be due to the hygroscopic behavior of the active polymer. The bandwidth of the modulator has been determined to be 4 MHz     

Determination of steroid hormones in bovine milk by LC-MS/MS and their levels in Swiss Holstein cow milk

Synthetic and natural steroid hormones have attracted some attention in recent years as endocrine active substances (EAS) that interact or interfere with the endocrine system. Endogenous hormones occur naturally in food of animal origin, among which bovine milk represents an important source. This study was conducted to determine the occurrence of steroid hormones (oestrogens, androgens, progestogens and glucocorticoids) in cow’s milk samples from three farms in Switzerland. An isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantification of 12 hormones in milk. Some hormonal levels from individual cows showed large variations. The average levels of the hormones analysed (17α-estradiol = 31 ng kg^–1, 17β-estradiol = 6 ng kg^–1, estrone = 159 ng kg^–1, 4-androstenedione = 684 ng kg^–1, progesterone = 15486 ng kg^–1, 17-hydroxyprogesterone = 214 ng kg^–1, cortisone = 112 ng kg^–1, and cortisol = 235 ng kg^–1) were comparable with literature data. Estriol, testosterone and androstenediols were not detected at their respective limit of quantification. No significant differences of hormonal content among milk from cows at different lactation/calving numbers were evidenced, except for progesterone and 4-androstenedione. Due to confounding parameters linked to the physiological stage of the animal, like pregnancy and gestational stage (pregnancy trimester), the causal correlation between the variation of the levels for these two hormones and the lactation/calving number could not be unambiguously demonstrated.     

Evaluation of a new rapid D-dimer assay for clinically suspected deep venous thrombosis (Liatest D-dimer)

In previous studies, enzyme-linked immunosorbent assays (ELISA) for plasma D-dimer analysis have demonstrated high sensitivity, suggesting their potential usefulness in excluding deep venous thrombosis (DVT). We evaluated the usefulness of a new D-dimer test (Liatest D-dimer) for suspected DVT in a prospective study of patients admitted to the hospital because of recent (not exceeding 1 week before admission) clinical signs. Contrast venography or compression ultrasonography or both were performed within 24 hours of admission. A new quantitative determination of D-dimer concentration using a suspension of microlatex particles coated with specific antibodies was tested. A standard plasma D-dimer ELISA measurement was also performed. Of 464 patients, 276 had a proven DVT (distal, 74; proximal, 202). For a cutoff level of 400 ng/mL, sensitivity of the Liatest method in the diagnosis of overall DVT was 94.6% (95% confidence interval, 92.0%-97.0%), and the specificity was 35% (95% confidence interval, 28%-42%). The sensitivity and negative predictive value were 98.5% and 95.6%, respectively, in the diagnosis of proximal DVT, but only 83.8% and 84.6%, respectively, in the diagnosis of distal DVT. This new rapid Liatest D-dimer assay seems to be highly sensitive and could replace the ELISA method in excluding patients with proximal DVT. Both methods provide lower sensitivity for distal DVT.     

Screening and confirmatory methods for the determination of melamine in cow’s milk and milk-based powdered infant formula: Validation and proficiency-tests of ELISA,HPLC-UV,GC-MS and LC-MS/MS

In recent years, two adulteration incidents concerning the addition of melamine, a small polar compound which is very rich in nitrogen, to pet food and infant formula products have occurred in China. These issues prompted private as well as governmental laboratories to develop methods for the analysis of melamine and related compounds in a wide variety of food products and ingredients. The development of methods was focussed on both, screening and quantification purposes, ranging from highly sophisticated chromatographic-mass spectrometric techniques to immuno-selective assays. The present work describes two screening and two confirmatory methods dedicated to the determination of melamine in cow’s milk and milk-based powdered infant formula. Screening methods are enzyme-linked immunosorbent assay (ELISA) and liquid chromatography coupled to ultraviolet detection, while confirmatory methods are based on gas and liquid chromatography coupled mass spectrometry techniques. Performance and validation data of the four methods, and results obtained in the frame of internal and European proficiency-tests are shown.     

Hyperimmunoglobulinemia D or periodic fever syndrome. Cutaneous manifestations in 3 cases

INTRODUCTION: We describe 3 cases of hyperimmunoglobulinemia D syndrome (hyper-IgD syndrome). CASES REPORT: As the 2 first cases are conventional with an onset in childhood, the third one appeared later suggesting possibility of acquired syndrome. The 3 cases presented with one or several skin eruptions during febrile attacks. COMMENTS: Up to now, 64 cases of this syndrome have been described. Skin lesions are observed in 80 p. 100 of patients. In this particular clinical context, they must lead to the diagnosis. This 3 cases and the review of literature show that skin manifestations are polymorphic, transient, not very symptomatic and not correlated to IgD rates. Histological examination may reveal urticarial reaction with leucocytoclasic vasculitis, where IgD could directly or not interact.     

Iterative space-time soft interference cancellation for UMTS-FDD uplink

Two efficient pilot-aided iterative space-time interference cancellation receivers are studied in order to increase the uplink capacity of the Universal Mobile Telecommunication System (UMTS) in frequency-division duplex (FDD) mode. Both iterative schemes use low-complexity beamforming and path combining techniques associated with soft-input soft-output decoding to mitigate the multiple-access interference in space and time. The difference between the two techniques is in the way they deal with unknown channels: the addition of a space-time channel estimation in each iteration on the one hand and iterative adaptive beamforming and path combining on the other hand. Thanks to the iterative structure, the observation signal used for estimation or adaptation contains less interference from one iteration to the following, and soft estimates of coded bits are available for data-aided estimation or adaptation. A detailed complexity analysis shows that renewing beamforming and path combining in each iteration without a-priori knowledge of the channel has no significant impact on the overall complexity of one iteration. Simulations of true UMTS-FDD uplink communications over a wideband directional channel model reveal that near-single user performance can be obtained for very high system loads, whereas more conventional receivers, such as the interference canceller without beamforming and the two-dimensional RAKE receiver, fail in recovering the transmitted information.