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21.
The texture of extruded starch products has been measured sensorially and instrumentally. The instrumental data were analyzed using different approaches such as fractal analysis and peak analysis. The data showed useful correlations between sensory crispness and crackliness and a parameter obtained from the application of a newly developed fractal method to analyze the force deformation curve obtained from a penetration test of the cereal samples. This suggests that fractal analysis of the force‐deformation plots could be used instead of sensory analysis. Moreover, it was observed that an increase in water content altered the texture of starch based samples from crispy to crackly, whereas the texture of starch‐sucrose samples remained unchanged in the same hydration range. © 2000 Society of Chemical Industry  相似文献   
22.
Aim of the present research is realization of a complex procedure on the basis of the combined approach for modeling aerodynamic loads on elements of the infrastructure (station constructions and designs, pedestrian crossings, bridges and tunnels) at high speed trains passage. Work is devoted to powerful methods of viscous gas currents modeling programs development and realization for research of aerodynamic loads on bodies making various movements, including shape variation, and to problems of bodies movement under aerodynamic forces solution.  相似文献   
23.
Early cleavages of Xenopus embryos were oriented in strong, static magnetic fields. Third-cleavage planes, normally horizontal, were seen to orient to a vertical plane parallel with a vertical magnetic field. Second cleavages, normally vertical, could also be oriented by applying a horizontal magnetic field. We argue that these changes in cleavage-furrow geometries result from changes in the orientation of the mitotic apparatus. We hypothesize that the magnetic field acts directly on the microtubules of the mitotic apparatus. Considerations of the length of the astral microtubules, their diamagnetic anisotropy, and flexural rigidity predict the required field strength for an effect that agrees with the data. This observation provides a clear example of a static magnetic-field effect on a fundamental cellular process, cell division.  相似文献   
24.
25.
Yeast species associated with the spontaneous fermentation of cider   总被引:1,自引:0,他引:1  
This paper reports the influence of cider-making technology (pneumatic and traditional pressing) on the dynamics of wild yeast populations. Yeast colonies isolated from apple juice before and throughout fermentation at a cider cellar of Asturias (Spain), during two consecutive years were studied. The yeast strains were identified by restriction fragment length polymorphism analysis of the 5.8S rRNA gene and the two flanking internal transcribed sequences (ITS). The musts obtained by pneumatic pressing were dominated by non-Saccharomyces yeasts (Hanseniaspora genus and Metschnikowia pulcherrima) whereas in the apple juices obtained by traditional pressing Saccharomyces together with non-Saccharomyces, were always present. The species Saccharomyces present were S. cerevisiae and S. bayanus. Apparently S. bayanus, was the predominant species at the beginning and the middle fermentation steps of the fermentation process, reaching a percentage of isolation between 33% and 41%, whereas S. cerevisiae took over the process in the final stages of fermentation. During the 2001 harvest, with independence of cider-making technology, the species Hanseniaspora valbyensis was always isolated at the end of fermentations.  相似文献   
26.
Application of the all-optical gain-controlled (AOGC) erbium-doped fiber amplifier (EDFA) for protection surviving channels in a multiwavelength network in which several EDFAs are cascaded is studied. The effects of addition and/or dropping of wavelength channels in a network comprising six concatenated EDFAs have been analyzed by numerical simulation. Only the first EDFA in the cascade is gain clamped using a ring laser configuration. A large-signal EDFA model which incorporates time variation numerical effects and the downstream propagation of signal and pump and downstream and upstream propagation of amplified spontaneous emission (ASE) has been used. In particular, the effects of relaxation oscillations from the gain-controlled EDFA on the surviving channel protection are investigated. It is shown that power excursions caused in an eight-channel wavelength division multiplexed (WDM) network by the loss/addition of 6 channels will be lower than 1 dB and free of relaxation oscillations if the gain-controlled EDFA is strongly inverted and the average normalized population density of the metastable level does not drop below 0.74  相似文献   
27.
The study evaluates the analgesic effects of epidural clonidine in patients undergoing abdominal hysterectomy under combined epidural/general anaesthesia. Forty ASA 1-2 patients were divided into two groups who received epidurally either clonidine 300 micrograms (group 1) or placebo (group 2). Anaesthesia was maintained with oxygen/nitrous oxide, a midazolam infusion, vecuronium, and boluses of fentanyl 100 micrograms administered as needed to maintain cardiovascular stability. The mean (SD) intraoperative fentanyl requirements were 2.05 (0.18) and 3.66 (0.3) micrograms.kg-1.h-1 for groups 1 and 2 respectively (p < 0.001). Patients in Group 1 had a lower heart rate after tracheal intubation and surgical incision (p < 0.02). In the recovery room, pain intensity was lower in group 1 (p < 0.003) and the mean (SD) time until analgesia request was increased from 48.5 (8.4) min in group 2 to 235.7 (33.2) min in group 1 (p < 0.001). Our results demonstrate that epidural clonidine produces decreased fentanyl requirements, improved cardiovascular stability, reduced pain intensity and effective postoperative analgesia in the recovery room.  相似文献   
28.
Today, in reliability analysis, the most used distribution to describe the behavior of electronic products under voltage profiles is the Weibull distribution. Nevertheless, the Weibull distribution does not provide a good fit to lifetime datasets that exhibit bathtub‐shaped or upside‐down bathtub–shaped (unimodal) failure rates, which are often encountered in the reliability analysis of electronic devices. In this paper, a reliability model based on the beta‐Weibull distribution and the inverse power law is proposed. This new model provides a better approach to model the performance and fit of the lifetimes of electronic devices. To estimate the parameters of the proposed model, a Bayesian analysis is used. A case study based on the lifetime of a surface mounted electrolytic capacitor is presented, the results showed that the estimation of the proposed model differs from the inverse power law–Weibull and that it affects directly the mean time to failure, the failure rate, the behavior, and the performance of the capacitor under analysis.  相似文献   
29.
Transfemoral amputation is a common amputation procedure for the human lower limbs. Passive, semi-active, and active prosthetic devices are usually prescribed to amputees in order to restore their quality of life (QOL) according to their abilities. From an engineering perspective, prosthetic and normal gait analysis, actuator technology, and biologic prosthetic control strategies are some of the current objects of study on active lower limb prosthetic design which aimed to reduce potential biomechanical disorders such as gait asymmetry or elevated metabolic cost due to the use of passive prosthetic devices. The main goal of active prosthetic design is to deliver prosthetic assistance at biological levels. This paper reviews the latest developments of semi-active and active prosthetics for transfemoral amputees; as well as the common design considerations and efficiency assessments performed on active transfemoral prosthetics under development in recent years.  相似文献   
30.
Reliability Model for Electronic Devices under Time Varying Voltage   总被引:1,自引:0,他引:1       下载免费PDF全文
Present reliability models, which estimate the lifetime of electronic devices, work under the assumption that the voltage level must be constant when an Accelerated Life Testing is performed. Nevertheless, in a real operational environment, electronic devices are subjected to electrical variations present in the power lines; that means the voltage has a time‐varying behavior, which breaks the assumption of reliability models. Thus, in this paper, a reliability model is presented, which describes the lifetime of electronic devices under time‐varying voltage via a parametric function. The model is based on the Cumulative Damage Model with random failure rate and the modified Inverse Power Law. In order to estimate the parameters of the proposed model, the maximum likelihood method was employed. A case study based on the time‐varying voltage induced by electrical harmonics when Alternate Current/Direct Current (AC/DC) transformer is connected to the power line is presented in this paper. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
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