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排序方式: 共有109条查询结果,搜索用时 15 毫秒
1.
A single-feed dual frequency compact microstrip antenna with a shorting pin is described. This new antenna configuration gives a large variation in frequency ratio of the two operating frequencies, without increasing the overall size of the antenna  相似文献   
2.

In recent years, Vehicular ad hoc networks (VANETs) could facilitate the decision-making progress of the drivers for example trip planning with the consideration of traffic. In the VANET, the Sybil attack is a very serious attack that collapses the security. In literature, some of the methods are reviewed to detect Sybil attacks in VANETs, but it fails to achieve Sybil attack detection. Hence, in this paper, Emperor Penguin Optimization-based Routing protocol (EPORP) is developed for detecting the Sybil attack which enhances the VANETs security. The main motive of the research is detecting the Sybil attack in VANETs for enhancing the secure operation. In the proposed approach, the Sybil attack will be detected with the help of the Rumour riding technique. To enhance the security of the VANETs, the Split XOR (SXOR) operation is utilized. In the SXOR operation, the optimal key is selected with the help of Emperor Penguin Optimization (EPO). The proposed method is implemented in the NS2 platform and performances are evaluated by metrics such as delay, throughput, delay, encryption time, and decryption time. The proposed method is compared with existing methods such as Whale Optimization Algorithm (WOA), Particle Swarm Optimization (PSO), and Firefly Algorithm (FA) respectively. While analyzing the delivery ratio, the proposed method has 0.96 s, and the WOA, PSO, and FA are 0.94, 0.92, and 0.90 respectively. From the analysis, the proposed method has a high delivery ratio value compared with the WOA, PSO, and FA methods. Similarly, the other parameters are analyzed and compared with the existing methods.

  相似文献   
3.
Use of oleogels prepared from hydrocolloids has recently gained considerable attention as an alternative for trans and saturated fats. Lately, pulse proteins such as faba bean protein and pea protein have been successfully used to prepare oleogels using a foam-templated approach. Although the pulse proteins are healthy oleogelators, high oil loss and low quality of cake baked using pulse protein-stabilized oleogels due to its poor rheological properties challenged its use. The present study explored whether the addition of small amount of high-melting monoglyceride (MAG) or candelilla wax (CW) can be used to improve the oil binding capacity, rheological properties, and baking qualities of pulse protein-stabilized oleogels composed of 5% faba bean or pea protein concentrate with 0.25% xanthan gum foams. Different concentrations (0.5–3%) of MAG or CW were dissolved in canola oil at 80 °C, followed by addition into the freeze-dried protein-polysaccharide foams (pH 7) and quickly transferred to a refrigerator to facilitate the formation of oleogels. The crystallized additives were found to be reinforcing the protein foam network in the oleogels. With increase in concentration of CW and MAG, the oil binding capacity, firmness, cohesiveness, and storage moduli of the oleogels were increased. Oleogels with and without MAG or CW were then characterized and tested for their performance as a shortening replacer in model baked cakes. Findings showed improved textural properties of cake upon addition of MAG in the foam-templated oleogels, however, compared to the shortening, negative effect on cake hardness and chewiness was still observed with the oleogels.  相似文献   
4.
A heterocyclic ligand synthesized by the coupling of diazotized 4-aminoantipyrine with acetylacetone reacted with lanthanide(III) nitrate to form complexes of the type [Ln(HAAP)2(NO3)3] where, Ln=La(III), Ce(III), Pr(III), Nd(III), Sm(III), or Gd(III) and HAAP= 3-{[2-(N-1-phenyl-2,3-dimethylpyrazol-3-in-5-on-4-yl)]hydrazone}pent-2,3,4-trione. The ligand and metal complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, UV-Visible, infrared, far infrared and proton NMR spectral data. The spectral data revealed that the ligand existed in the hydrazo form and coordinated to the metal ion without deprotonation in a neutral tridentate manner, through carbonyl oxygen of pyrazolone ring, hydrazo nitrogen and carbonyl oxygen of the acetylacetone moiety. The molar conductance values adequately supported their non-electrolytic nature. The ligand and the praseodymium(III) complex were subjected to X-ray diffraction studies. Thermal decomposition behavior of the lanthanum(III) complex was also examined.  相似文献   
5.
A bishydrazone formed by the condensation of isatinmonohydrazone and salicylaldehyde reacted with lanthanide(Ⅲ) chloride to form complexes of the type [Ln(HISA)2Cl3], where, Ln=La(Ⅲ), Ce(Ⅲ), Pr(Ⅲ), Nd(Ⅲ), Sm(Ⅲ), Eu(Ⅲ), or Gd(Ⅲ) and HISA= [(2-hydroxybenzaldehyde)-3-isatin]bishydrazone. Both reactions were carried out under microwave conditions. The ligand and the metal complexes were characterized on the basis of elemental analysis, molar conductance, magnetic susceptibility measurements, UV visible, infrared, far infrared, and proton NMR spectral data. The ligand acted as neutral tridentate, coordinating through the carbonyl oxygen, azomethine nitrogen, and phenolic oxygen without deprotonation. The ligand and lanthanum(Ⅲ) complex were subjected to X-ray diffraction studies. The X-ray diffraction pattern of ligand exhibited its crystalline nature and that of the lanthanum(Ⅲ) complex indicated its amorphous character. The thermal decomposition behaviour of the complex, [La(HISA)2Cl3], was examined in the temperature range of 40-800 ℃ using TG, DTG, and DTA. The ligand and the metal complexes were screened for their antifungal activities.  相似文献   
6.
Hydroxyapatite filled chitosan-polyacrylic acid polyelectrolyte complexes   总被引:4,自引:0,他引:4  
Chitosan (CHI) has been complexed with polyacrylic acid (PAA) in the presence of hydroxyapatite (HAP) to prepare composites intended for bone substitute applications. Thermogravimetric analysis of the composite showed that the presence of HAP had little effect on the degradation profile of the polyelectrolyte complex (PEC), except for the onset of degradation. Optimum compressive strength was observed for 70-weight percentage HAP filled PEC. The morphological analysis revealed that the HAP particles were uniformly distributed in the PEC matrix. The results indicate that HAP filled PEC of CHI and PAA could be prepared following the proposed simple route.  相似文献   
7.
A novel compact microstrip fed dual-band coplanar antenna for wireless local area network is presented. The antenna comprises of a rectangular center strip and two lateral strips printed on a dielectric substrate and excited using a 50 Omega microstrip transmission line. The antenna generates two separate resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. Lower resonant mode of the antenna has an impedance bandwidth (2:1 VSWR) of 330 MHz (2190-2520 MHz), which easily covers the required bandwidth of the 2.4 GHz WLAN, and the upper resonant mode has a bandwidth of 1.23 GHz (4849-6070 MHz), covering 5.2/5.8 GHz WLAN bands. The proposed antenna occupy an area of 217 mm2 when printed on FR4 substrate (epsivr=4.7). A rigorous experimental study has been conducted to confirm the characteristics of the antenna. Design equations for the proposed antenna are also developed  相似文献   
8.
The impedance bandwidth of a high permittivity cylindrical dielectric resonator antenna excited by a microstrip line was significantly improved by modifying the feed geometry. The 10 dB return loss bandwidth is enhanced from 12 to 26% without much affecting the gain and other radiation properties of the antenna. Good agreement has been observed between the predicted and measured results.  相似文献   
9.
Pubertal mammary gland growth and development are hormonally regulated, but the details are poorly understood in calves. Our purpose was to evaluate the effects of exogenous growth hormone (GH) on the biochemical composition of the prepubertal mammary gland, mRNA expression of selected genes, and histological characteristics of the developing parenchyma (PAR). In this experiment, 19 calves (7 ± 4 d of age) were randomly assigned to 1 of 2 treatments: bovine somatotropin (bST, 500 mg; n = 10) or placebo (Sal; 0.9% saline; n = 9). Animals were treated every 3 wk beginning on d 23. Calves were assigned to an early (65 d; tissue harvested after 2 treatment injections) or late collection time (107 d; tissue harvested after 4 treatment injections). Calves were fed milk replacer and calf starter for 8 wk and starter and hay thereafter. Parenchyma and mammary fat pad (MFP) from one udder half were harvested for analysis of protein, lipid, and DNA. Additional tissues were preserved for histological analysis or snap-frozen for quantitative real-time PCR. Somatotropin treatment did not significantly alter the mass of PAR or MFP or the general pattern of development of epithelial structures. Significant increases were observed in protein/100 kg of body weight (BW), total protein, DNA concentration, DNA/100 kg of BW, and total DNA in 107-d calves, and a significant treatment by day interaction was observed for DNA and lipid concentrations in PAR. In MFP, a significant decrease was observed in protein/100 kg of BW in bST-treated calves and in total MFP protein in 65-d calves. A treatment by day interaction was found for total protein, DNA, and protein/100 kg of BW. In PAR, relative expression of ATPase-binding cassette 3 and growth hormone receptor were reduced by bST and both were lower in 107-d-harvest calves. Epithelial cell retention of bromodeoxyuridine (BrdU; possible indicator of stem-like cells) was greatest in 65-d bST-treated calves, and a significant time of sampling response and treatment × time interaction were observed. Expression of the proliferation marker protein Ki67 was numerically higher in bST-treated calves but the difference was nonsignificant. Retention of the BrdU label was reduced in 107-d calves. Exogenous growth hormone given to calves may affect mammary tissue composition and epithelial cell gene expression in subtle ways but exogenous supplementation with bST alone is not likely to alter overall development patterns or affect the mass of mammary parenchymal tissue. Whether such subtle changes have an effect on subsequent development or function is unknown.  相似文献   
10.
Electromagnetic scattering behaviour of a superstrate loaded metallo-dielectric structure based on Sierpinski carpet fractal geometry is reported. The results indicate that the frequency at which backscattering is minimum can be tuned by varying the thickness of the superstrate. A reduction in backscattered power of /spl sim/44 dB is obtained simultaneously for both TE and TM polarisations of the incident field.  相似文献   
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