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1.
Product development involves many experts collaborating to the same design goal. Every expert has his own formalisms and tools leading to a high heterogeneity of information systems supporting design activities. Interoperability became a major challenge to avoid information incompatibility along the product life cycle. To synchronise heterogeneous representations of product will be a major step to integrate expert activities. In this paper, the authors propose a meta-model framework to connect together heterogeneous design models. This meta-model framework is used to formalise possible interactions between heterogeneous representations. Interaction formalisation is considered as a key point to synchronise heterogeneous models and to provide more interoperability between various computer assisted systems. The synchronisation loop is also presented as a major sequence of activities to manage collaborative design. Tools to support synchronisation are proposed. However, through a basic case study, authors highlight what can be automated and where human intervention is still expected.  相似文献   
2.
A thermo-hydro-mechanical coupled model is presented here in order to simulate the transient creep strain of the load induced thermal strain of concrete during a heating–cooling cycle with a concomitant applied load. In this paper, the transient creep strain is split into a drying creep component and a dehydration creep strain. Further, a dehydration variable is introduced to describe chemical transformations due to the temperature increase. It also allows to govern the occurrence of the transient creep strain. Moreover, in this approach, we consider that the dehydration creep occurs with the same kinetics as the dehydration process. This model has been implemented in the finite element code CAST3M and numerical simulations are performed to assess the capability of the model to predict transient load induced thermal behavior of concrete in the case of a heating cooling cycle.  相似文献   
3.
We report on the in situ synthesis through sol-gel processing of a tellurium dioxide (TeO2)–cellulose–polyvinyl alcohol (PVA) hybrid composite. The cellulose–PVA hybrid composite was synthesized through chemical graft in the presence of aqueous sodium hydroxide. Field emission scanning electron microscopy, SEM-EDX, high-resolution transition microscopy (FE-TEM) revealed that polycrystalline nanorods were uniformly distributed with sizes of 20?nm in the cotton cellulose–PVA–TeO2 hybrid nanocomposite. The average size of TeO2 crystallite was calculated to be 0.292?nm, as shown in the FE-TEM, SAED, and X-ray diffraction analysis. Furthermore, the hybrid nanocomposites were studied for their antimicrobial activity against Bacillus cereus and Escherichia coli strains, which was inhibited at a size of 10–12?mm after 24?h of incubation.  相似文献   
4.
Characterization of NADPH oxidase 5 in equine testis and spermatozoa   总被引:2,自引:0,他引:2  
Reactive oxygen species (ROS) play an important role in normal sperm function, and spermatozoa possess specific mechanisms for ROS generation via an NAD(P)H-dependent oxidase. The aim of this study was to identify the presence of an NADPH oxidase 5 (NOX5) in equine testis and spermatozoa. The mRNA of NOX5 was expressed in equine testis as detected by northern blot probed with human NOX5 cDNA and by RT-PCR. Immunoblotting with affinity purified alpha-NOX5 revealed one major protein in equine testis and other tissues. Immunolocalization of NOX5 showed labeling over the rostral sperm head with some labeling in the equatorial and post-acrosomal regions. In the testis, there was abundant staining in the adluminal region of the seminiferous tubules associated with round and elongating spermatids. The RT-PCR and sequence analysis revealed a high homology with human NOX5. This study demonstrates that NOX5 is present in equine spermatozoa and testes and therefore represents a potential mechanism for ROS generation in equine spermatozoa.  相似文献   
5.
In this paper, the variations of elastic strain and Young modulus of high performance concrete and ordinary concrete during a heating?Ccooling cycle is presented. For the HPC, two heating rates are applied: 1.5 and 0.1?°C/min corresponding respectively to accidental and service conditions. For ordinary concrete, the results of service conditions are given. The temperatures of 400 and 220?°C are the heating??s final temperature phase of the accidental and service conditions respectively. The present work analyses the differences between the value of the elastic strain and the Young??s modulus at the beginning of the test (at ambient temperature), the end of the heating part and the end of the cooling part of each variation. Indeed, during the heating phase, the corresponding heating rates are applied until successive constant temperature levels are achieved: 150, 200, 300 and 400?°C for the high-performance concrete under accidental conditions and 140, 190 and 220?°C for both high-performance and ordinary concrete under service conditions. Those applied temperatures are maintained for several hours to ensure the stabilisation of internal temperature and physico-chemical thermo dependent processes. Moreover, the influence of the difference in mix concretes between the two types of concretes and the heating rate influence on those variations is also presented.  相似文献   
6.
We showed previously that thyroid antagonists and glucocorticoids partially alleviated the impaired righting ability and abnormally high levels of plasma creatine kinase activity in genetically dystrophic chicks. The goals of the present study were: (1) to ascertain whether the beneficial effects of methimazole (MMI; thyroid antagonist) on muscle function and plasma creatine kinase (CK) activity in dystrophic chickens are correlated with significant reduction in plasma triiodothyronine (T3) and thyroxine (T4); (2) to assess whether the MMI-induced thyroid changes are accompanied by increased plasma corticosterone level and/or changes in muscle glucocorticoid receptors which might account partially for the beneficial effects of MMI; and (3) to determine if plasma T3 and T4 are reduced in dexamethasone (DEX) treated dystrophic chickens which might account at least partially for the beneficial effects of DEX (a potent glucocorticoid) on avian dystrophy. The data show that beneficial effects of MMI are associated with reduced plasma levels of thyroid hormones and increased circulating levels of corticosterone. In addition, DEX actually increases plasma T3 levels. These differential effects indicate that reduced plasma thyroid hormone levels do not represent a common mechanism of beneficial drug effects in avian muscular dystrophy. On the other hand, elevated plasma glucocorticoid levels accompany the beneficial effects of both severe hypothyroidism and DEX treatment. The data also show that MMI induces down-regulation of muscle cytosolic glucocorticoid receptors which are higher than normal in dystrophic muscles.  相似文献   
7.
The present study focused on reflex relationships between the esophagus and the respiratory system in cats, namely the changes in airway tone and pulmonary circulation elicited by mechanical or acid (pH 2) stimulation of esophageal afferents. One-minute of sustained distension of the cervical esophagus increased tracheal pressure (PTr), decreased pulmonary artery pressure (PPA) and to a higher extent pulmonary blood flow (QPA) and lowered arterial blood pressure (Pa). This was associated with significant variations in arterial blood gases (increased PaO2 and decreased PaCO2). Acid stimulation of the cervical esophagus caused a marked increase in PTr and a modest fall in QPA. In both circumstances, cervical bivagotomy abolished PTr changes, whereas the changes in pulmonary hemodynamics but not in Pa were then accentuated. Further cervical sympathectomy suppressed the vascular response. These observations show the existence of reflex influences of esophageal afferents on the control of airway tone and pulmonary vascular resistance. The vagus nerve is the efferent arm of the bronchomotor reflex whereas modulation of the sympathetic control of pulmonary circulation seems to be responsible for the changes in pulmonary hemodynamics.  相似文献   
8.
This paper introduces a neural network optimization procedure allowing the generation of multilayer perceptron (MLP) network topologies with few connections, low complexity and high classification performance for phoneme’s recognition. An efficient constructive algorithm with incremental training using a new proposed Frame by Frame Neural Networks (FFNN) classification approach for automatic phoneme recognition is thus proposed. It is based on a novel recruiting hidden neuron’s procedure for a single hidden-layer. After an initializing phase started with initial small number of hidden neurons, this algorithm allows the Neural Networks (NNs) to adjust automatically its parameters during the training phase. The modular FFNN classification method is then constructed and tested to recognize 5 broad phonetic classes extracted from the TIMIT database. In order to take into account the speech variability related to the coarticulation effect, a Context Window of Three Successive Frame’s (CWTSF) analysis is applied. Although, an important reduction of the computational training time is observed, this technique penalized the overall Phone Recognition Rate (PRR) and increased the complexity of the recognition system. To alleviate these limitations, two feature dimensionality reduction techniques respectively based on Principal Component Analysis (PCA) and Self Organizing Maps (SOM) are investigated. It is observed an important improvement in the performance of the recognition system when the PCA technique is applied. Optimal neuronal phone recognition architecture is finally derived according to the following criteria: best PRR, minimum computational training time and complexity of the BPNN architecture.  相似文献   
9.
The objective of the work is two-fold. A first part is devoted to the problem of constructing an observer to the practical system called overhead crane with the position as output. In a second part, the problem of global output feedback stabilisation is solved for a class of Euler–Lagrange systems when the variables of velocity are the unmeasured part of the state. The equations of these systems are non-linear with respect to the velocities. A new output feedback control scheme is proposed. It relies on the determination of a change of coordinates which gives to the systems a triangular form. To illustrate the approach, it is applied to a two-link manipulator.  相似文献   
10.
This study evaluated the effect of a GnRH analogue conjugated to the cytotoxin, pokeweed antiviral protein (PAP), on reproductive function in adult, male dogs. Four dogs received 0.0042 mg GnRH-PAP kg(-1) hourly for 36 h, and four other dogs received 0.1 mg GnRH-PAP kg(-1) as one bolus injection daily for three consecutive days. One dog received a single bolus (0.1 mg x kg(-1)). Three adult male dogs received GnRH without the PAP conjugate, as controls. Twenty-five weeks after the initial treatment, all treated dogs received 0.1 mg GnRH-PAP kg(-1) as a single administration, whereas dogs in the control group received 0.0045 mg kg(-1) of the GnRH analogue. Serum concentrations of testosterone and LH were determined by radioimmunoassay, and testis size was measured for 9 months after treatment. Stimulation tests (5 microg GnRH kg(-1)) were used to evaluate LH release (-15, 0, 30, 60, 90, 120 min), which was assessed by measuring area under the curve. Serum testosterone concentrations were significantly lower (P<0.05) after treatment in the bolus and hourly groups than in the control group. Testosterone concentrations fell to less than 50 pg x ml(-1) in three of four dogs in the bolus group and one of four dogs in the hourly group by week 8-9 after treatment. Basal LH was lower (P<0.05) in the bolus and hourly groups than in the control group between weeks 0 and 33 after treatment. Treatment with GnRH-PAP reduced (P<0.05) LH release after GnRH stimulation in the bolus and hourly groups compared with the control group. Testis volume was lower (P<0.05) in all treated versus control dogs. In conclusion, administration of the conjugate GnRH-PAP at a 25 week interval resulted in a major disruption of reproductive parameters in male dogs; this effect was maintained for 11-12 weeks after a second injection of GnRH-PAP.  相似文献   
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