This work deals with the development of a numerical method for solving an inverse problem for bending stiffness estimation in a Kirchhoff–Love plate from overdetermined data. The coefficient is identified using a technique called the Method of Variational Imbedding, where the original inverse problem is replaced by a minimization problem. The Euler–Lagrange equations for minimization comprise higher-order equations for the solution of the displacement and an equation for the bending stiffness. The correctness of the embedded problem is discussed. A difference scheme and a numerical algorithm for solving the parameter identification problem are developed. Numerical results for the obtained values of the bending stiffness as an inverse problem are presented. 相似文献
The damage induced in the thin SiO2–Si system after an exposure to O2 and N2 plasma working in reactive ion etching (RIE) mode has been studied. A generation of high density (up to 5×1012 cm−2 in the first 15 s plasma exposure) of positive oxide charge in bulk traps as well as in slow states has been established. The RIE damage effects become highly process dependent as the plasma time increases, the fixed oxide charge first increases and then slows down or even turns around depending on discharge conditions. It is suggested that the relative contribution of the two main plasma components (ion bombardment and vacuum UV photons) at different discharge regimes is the reason for the appearance or the absence of the “turn-around” effect. It is established that the combination O2 plasma and low pressure is critical for the degradation of the plasma treated samples. The results reveal a strong linear correlation between the leakage current detected and plasma created positive charge. 相似文献
Of 509 samples from poultry flocks, 209 isolates (41.1%) were Campylobacter positive. The number of positive cases in broiler carcasses was 45.9%. Of 52 pheasants investigated, 25.9% were Campylobacter positive. Campylobacter jejuni was isolated from 86 (42.0%) poultry flock samples, 47 (43%) broiler samples and 15 (28%) wild pheasant samples. C. coli was found at a rate of 1.2% in poultry flocks, 13% in broilers and 21% in pheasants. 相似文献
Tantalum pentoxide films (13–260 nm) on p-type Si have been prepared by thermal oxidation at 673–873 K of rf sputtered Ta films and have been studied using Al–Ta2O5–Si capacitors. Both dielectric constant and refractive index were found to depend on the thickness of the Ta2O5 layers. Layers with a dielectric constant of 25–32 were obtained. A decreasing trend in the leakage current was found upon increasing oxidation temperature from 673 to 873 K. Leakage current density of (10−8 to 3×10−7) A cm−2 at 1 MV cm−1 effective field was achieved. 相似文献
Stress-induced leakage currents (SILCs) in thin Ta2O5 films after short- and long-term constant current stress (CCS) at both gate polarities at different levels of injected current were investigated. The behavior of the SILCs and the change of quasistatic C–V characteristics after the degradation confirmed the variations of gate voltage with time during CCS necessary to maintain the injected current density through the oxide.The conduction mechanisms were also investigated. Initially, normal Poole–Frenkel (PF) mechanism dominates in the oxide at medium fields (0.4– 1.7 MV/cm) independently of the deposition temperature or annealing steps. After the degradation modified PF with different compensation factors appears. After long-term degradation conduction mechanism goes back to PF. 相似文献
Metal-insulator-silicon structures containing Hf-doped Ta2O5 dielectric films sputtered on rapid thermally nitrided Si are shown to have very good reliability properties. Stress-induced leakage currents are low, both at low and at high-fields. It is found that charge trapping during the stress is the dominant wear-out mode for very long stress times of 500 s even for injected current densities Js as high as 100 mA/cm2. Stress curves approach saturation at long stress time, indicating that the trap generation rate is very low, even compared to the observed reduced trapping at pre-existing traps.Applying a trapping kinetics model, two trapping sites with characteristic trapping times τ1 = 3.2 s and τ2 = 49 s were determined and attributed to pre-existing defects in the bulk Hf:Ta2O5 layer and not in the interfacial SiOxNy layer. It was found that both τ1 and τ2 do not depend on Js, which may be explained by the presence of a mechanism of charging the active sites through field activated emission of charge from them. 相似文献
Auger electron spectroscopy, low-energy electron loss spectroscopy and infrared spectroscopy are used to investigate the nitridation of thin (10–22 nm) thermal SiO2 in RF soft NH3 plasma. It is found that plasma action at a substrate temperature of 573 K can completely nitridate the thermal oxide to an oxynitride layer. The layers obtained are macroscopic mixtures of two phases SiO2 and Si3N4, rather than amorphous polymers of Si, O and N. 相似文献
This study investigated whether transient, neonatal (days 2-12) treatment of rats with the potent oestrogen, diethylstilboestrol (DES), altered the structure of the cauda epididymis/vas deferens in adulthood, and if the changes observed related to altered development of basal cells in early puberty. Neonatal treatment with 10 microg DES resulted in the following during adulthood: (a) coiling of the normally straight initial vas deferens, (b) gross epithelial abnormalities, (c) 4-fold widening of the periductal non-muscle layer, (d) infiltration of immune cells across the epithelium into the lumen, and (e) reduction/absence of sperm from the vas deferens lumen. Amongst affected animals>75% exhibited reduced epithelial immunoexpression of androgen receptor and aberrant oestrogen receptor-alpha immunoexpression and 63% exhibited multi-layering of basal cells coincident with increased epithelial cell proliferation. None of the aforementioned changes occurred in rats treated neonatally with 0.1 microg DES.As basal cells play a key role in the development of epithelia such as that in the epididymis and vas deferens, we went on to investigate if neonatal DES treatment affected basal cell development. In controls, basal cells were first evident at day 10 (vas deferens) or day 18 (cauda). Rats treated with 10 microg, but not those treated with 0.1 microg, DES, showed approximately 90% reduction (P<0.001) in basal cell numbers at day 15 and day 18. This decrease coincided with gross suppression of testosterone levels; co-treatment of rats with 10 microg DES+testosterone maintained basal cell numbers at control levels at day 18. However, suppression of testosterone production (GnRH antagonist treatment) or action (flutamide treatment) did not alter basal cell numbers. It is concluded that neonatal exposure to high oestrogen levels coincident with reduced testosterone action results in abnormal changes in the adult cauda/vas deferens that are preceded by delayed differentiation of basal cells. These findings imply a role for androgens and oestrogens in basal cell development and suggest that this may be pivotal in determining normal epithelial (and stromal) development of the cauda/vas deferens. 相似文献
N‐Methylol reagents are conventional crosslinking agents that are still widely used in textile industry to produce crease‐resistant cotton fabrics. In this work serine proteases were used to recover the strength of fabrics, cross‐linked with N‐hydroxymethylacrylamide. Nearly one half of the strength loss of crosslinked cotton fabrics could be restored after protease treatment, while the wrinkle recovery angle (WRA) decreased only slightly. The enzymatic hydrolysis of the amide cross‐links in the durable pressed cellulose was confirmed by FT‐IR analysis and dyeability with an acid dye.
Effect of protease concentration on the tensile strength recovery, WRA and acid dye dyeability at 30 min reaction time. 相似文献
Tantalum pentoxide thin films on Si prepared by two conventional for modern microelectronics methods (RF sputtering of Ta in Ar + O2 mixture and thermal oxidation of tantalum layer on Si) have been investigated with respect to their dielectric, structural and electric properties. It has been found that the formation of ultra thin SiO2 film at the interface with Si, during fabrication implementing the methods used, is unavoidable as both, X-ray photoelectron spectroscopy and electrical measurements, have indicated. The initial films (as-deposited and as-grown) are not perfect and contain suboxides of tantalum and silicon which act as electrical active centers in the form of oxide charges and interface states. Conditions which guarantee obtaining high quality tantalum oxide with dielectric constant of 32–37 and leakage current density less than 10−7 A/cm2 at 1.5 V applied voltage (Ta2O5 thickness equivalent to about 3.5 nm of SiO2) have been established. These specifications make the layers obtained suitable alternative to SiO2 for high density DRAM application. 相似文献