Thin films of polymethyl methacrylate (PMMA) were synthesized. Ferric oxalate was dispersed in PMMA films. These films were irradiated with 80 MeV O6+ ions at a fluence of 1×1011 ions/cm2. The radiation induced changes in electrical conductivity, Mössbauer parameter, microhardness and surface roughness were investigated. It is observed that hardness and electrical conductivity of the film increases with the concentration of dispersed ferric oxalate and also with the fluence. It indicates that ion beam irradiation promotes (i) the metal to polymer bonding and (ii) convert the polymeric structure into hydrogen depleted carbon network. Thus irradiation makes the polymer harder and more conductive. Before irradiation, no Mössbauer absorption was observed. The irradiated sample showed Mössbauer absorption, which seems to indicate that there is significant interaction between the metalion and polymer matrix. Atomic force microscopy shows that the average roughness (Ra) of the irradiated film is lower than the unirradiated one. 相似文献
BACKGROUND: Twin reversed arterial perfusion (TRAP) sequence and development of an acardiac monster is a rare event. Even more rare are conjoined acardiac, acephalic twins complicating a triplet pregnancy with TRAP sequence. The mortality for the acardius is 100%, and morbidity for the normal, pump fetus is 50%. The morbidity of the pump twin or triplet is attributed mostly to in utero congestive heart failure. CASE: A 24-year-old woman, gravida 1, para 0, at 35 weeks' intrauterine pregnancy, gave birth via low transverse cesarean section to a normal female and a pair of conjoined, acardiac, acephalic, pelvipagus twins. CONCLUSION: The diagnosis of acardius in multiple gestation pregnancy, with no fetal heart tone on ultrasound, must be ruled out in every case so that proper counseling, management and avoidance of complications in these patients can be achieved. 相似文献
This report describes results of a survey conducted to assess the variability in drug release from the USP calibrators and its dependence on various deaeration methods. The calibrator data submitted by 33 laboratories, involved tests of 1659 sets (6 or 12 tablets/set) from four lots of prednisone and salicylic acid each, using apparatuses 1 & 2 run at 50 and 100 rpm. Overall variabilityranges for the individual sets, which met the USP dissolution apparatus Suitability Criteria, were 0.5-31.3% for prednisone/apparatus 1, 0-13.2% for salicylic acid/apparatus 1, 0.3-10.2% for prednisone/apparatus 2 and 0.7-20.2% for salicylic acid/apparatus 2. The results of this survey suggest that variability levels are dependent on apparatus/calibrator combination. Although deaeration of dissolution media tends to reduce the failures i.e. not meeting the Suitability Criteria, its effect on reducing the variability appears to be minimal. Among the various deaeration methods reported, degassing the media by a combination of heating with helium sparging or with filtering under vacuum tend to give the lowest failure rate. From our findings, a variability of up to 31% CV (coefficient of variation) in percent drug release for the calibrator can occur with the samples still meeting the USP criteria. However, if the apparatus/calibrator combination is taken into consideration with appropriate deaeration method, the maximum expected variability can be reduced to 10% or less. The results of this survey show that rather than an eight point dissolution calibration test criteria, a four point evaluation system i.e. testing non-disintegrating tablets with apparatus 1 and disintegrating tablets with apparatus 2 may provide sufficient information for system suitability. It is also recommended that a similar formulation/apparatus combination should be considered for drug products evaluation which might yield less variable results with an improved potentials of in vitro/in vivo correlations particularly for modifieddrug release products. 相似文献
The high-temperature oxidation behavior of aluminized Inconel 625 has been examined using scanning electron microscopy (SEM)
and fine-probe spot and linescan energy dispersive spectroscopy (EDS) microanalysis techniques. The formation of adherent
slowly growing metallic coatings is essential for protection against severe environments. The coated (aluminized) and uncoated
samples were subsequently oxidized in air at 1000 and 1100 °C to examine the performance of the aluminized coating. The micro-structural
changes that occurred in both coated and uncoated samples were examined. It was found that coated samples showed superior
performance against high-temperature oxidation, as compared to the uncoated samples. The coated samples revealed uniform and
adherent oxidized layer, as compared to the uncoated samples. The oxidation behavior and multilayered microstructural morphology
observed in the coated samples can be attributed to the interdiffusion and variation in kinetics of oxidation. 相似文献
We propose a new algorithm for image compression based on compressive sensing (CS). The algorithm starts with a traditional multilevel 2-D Wavelet decomposition, which provides a compact representation of image pixels. We then introduce a new approach for rearranging the wavelet coefficients into a structured manner to formulate sparse vectors. We use a Gaussian random measurement matrix normalized with the weighted average Root Mean Squared energies of different wavelet subbands. Compressed sampling is finally performed using this normalized measurement matrix. At the decoding end, the image is reconstructed using a simple ?1-minimization technique. The proposed wavelet-based CS reconstruction, with the normalized measurement matrix, results in performance increase compared to other conventional CS-based techniques. The proposed approach introduces a completely new framework for using CS in the wavelet domain. The technique was tested on different natural images. We show that the proposed technique outperforms most existing CS-based compression methods. 相似文献
The detection of fully and partially defective sensors in a linear array composed of N sensors is addressed. First, the symmetrical structure of a linear array is proposed. Second, a hybrid technique based on the cultural algorithm with differential evolution is developed. The symmetrical structure has two advantages: (1) Instead of finding all damaged patterns, only (N–1)/2 patterns are needed; (2) We are required to scan the region from 0° to 90° instead of from 0° to 180°. Obviously, the computational complexity can be reduced. Monte Carlo simulations were carried out to validate the performance of the proposed scheme, compared with existing methods in terms of computational time and mean square error. 相似文献
Frequency diverse array (FDA) radar has been proposed in last decade for joint range and angle beamforming of a target. Multiple input multiple output-frequency diverse array (MIMO-FDA) radar has also been presented recently in literature to steer multiple beams by creating subarrays in transmit array. These beams help to localize the target in range as well as angle dimension. Due to same subarray size, all the beams have same beamwidth and thus exhibit same response for a given target. In this paper, we have proposed an unequal size subarrays structure for the FDA radar (US-MIMO-FDA), which allow us more focusing of the target in range and angle dimension by using beams of variable width. As a result the echoes received at the receiver help in better estimation of target parameters. The effectiveness of proposed scheme has been shown by comparing transmit and received beam patterns of proposed scheme with MIMO-FDA with equal subarrays Performance analysis of proposed scheme has also been done in terms of output signal to interference plus noise ratio, detection probability and cramer-rao lower bound. Simulation and results have verified better focusing of target by proposed design as compared to existing subarrays schemes for MIMO-FDA. 相似文献
Interest in real-time systems has grown considerably over recent years, primarily due to significant increase in the use of smart technologies and latency-sensitive applications such as cloud gaming, audio/video streaming, and smart homes. Significant work has been done on resource mapping in the cloud environment, and a number of promising results have been established accordingly where the focus is mainly on resource provisioning. However, the applicability of cloud computing services for real-time systems generated from smart systems is still in its infancy and remains unexplored, relatively. To address this gap, we propose a model for the smart systems that periodically offload computational workload to the cloud environment where virtual machines are allocated according to rate-monotonic scheduling policy to ensure requests are processed within the associated deadlines. Deadlines of tasks have been relaxed to improve server utilization as well as maintain a level of confidence in the timing constrains. Experimental results are discussed to highlight the applicability of static priority assignment for the workload in the context of virtual machines allocation.
The performance of UV/H2O2, UV/O3, and UV/H2O2/O3 oxidation systems for the treatment of municipal solid-waste landfill leachate was investigated. Main objective of the experiment was to remove total organic carbon (TOC), non-biodegradable organic compounds (NBDOC) and color. In UV/H2O2 oxidation experiment, with the increase of H2O2 dosage, removal efficiencies of TOC and color along with the ratio of biochemical oxygen demand (BOD) to chemical oxygen demand (COD) of the effluent were increased and a better performance was obtained than the system H2O2 alone. In UV/H2O2 oxidation, under the optimum condition H2O2 (0.2 time), removal efficiencies of TOC and color were 78.9% and 95.5%, respectively, and BOD/COD ratio was significantly increased from 0.112 to 0.366. In UV/O3 oxidation, with the increase of O3 dosage, removal efficiencies of TOC and color along with BOD/COD ratio of the effluent were increased and a better performance was obtained than the system O3 alone. Under the optimum condition UV/O3 相似文献