332 research outputs found

    Decision Combining in Relay Networks

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    We consider non-coherent detection of M-ary FSK modulated signals transmitted over a slow, Rayleigh fading channel in a wireless relay network. The network consists of a single source-destination pair and a number of relays (L), which employ cooperative diversity. Performances of a counting rule and square law combiner are studied. We derive closed form expressions for probabilities of error for equal relay channel average SNR. For unequal relay channel SNRs, we resort to Monte Carlo simulations to estimate the error probabilities. We examine different combinations of M and L for a range of average SNR values. Although the square law combiner outperforms the counting rule for equal and small average SNRs, the loss in performance is not high. Simplicity of counting rule may be advantageous in these cases

    Ruthenium and osmium carbonyl clusters incorporating stannylene and stannyl ligands

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    The reaction of [Ru₃ (CO)₁₂] with Ph₃SnSPh in refluxing benzene furnished the bimetallic Ru-Sn compound [Ru₃(CO)₈(μ-SPh)₂(μ3-SnPh₂)(SnPh₃)₂] 1 which consists of a SnPh₂ stannylene bonded to three Ru atoms to give a planar tetra-metal core, with two peripheral SnPh₃ ligands. The stannylene ligand forms a very short bond to one Ru atom [Sn-Ru 2.538(1) Å] and very long bonds to the other two [Sn-Ru 3.074(1) Å]. The germanium compound [Ru₃(CO)₈(μ-SPh)₂(μ₃-GePh₂)(GePh₃)₂] 2 was obtained from the reaction of [Ru₃ (CO)₁₂] with Ph₃GeSPh and has a similar structure to that of 1 as evidenced by spectroscopic data. Treatment of [Os₃(CO)₁₀(MeCN)₂] with Ph₃SnSPh in refluxing benzene yielded the bimetallic Os-Sn compound [Os₃(CO)₉(μ-SPh)(μ₃-SnPh₂)(MeCN)(ƞ¹-C₆H₅)] 3. Cluster 3 has a superficially similar planar metal core, but with a different bonding mode with respect to that of 1. The Ph₂Sn group is bonded most closely to Os(2) and Os(3) [2.7862(3) and 2.7476(3) Å respectively] with a significantly longer bond to Os(1), 2.9981(3) Å indicating a weak back-donation to the Sn. The reaction of the bridging dppm compound [Ru₃(CO)₁₀(μ-dppm)] with Ph₃SnSPh afforded [Ru₃(CO)₆(μ-dppm)(μ₃-S)(μ₃-SPh)(SnPh₃)] 5. Compound 5 contains an open triangle of Ru atoms simultaneously capped by a sulfido and a PhS ligand on opposite sides of the cluster with a dppm ligand bridging one of the Ru-Ru edges and a Ph₃Sn group occupying an axial position on the Ru atom not bridged by the dppm ligand

    Microstrip Patch Antenna for GPS Application

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    The study and the design of rectangular microstrip patch antenna for multiband applications are presented in this paper. They can be simulated on antenna design software’s such as High Frequency Simulation Software (HFSS), Advanced Design System Momentum (ADS) and Agilent Vector Network Analyzer (E8361A) where different feeding techniques have been deployed to get the desired results. Two rectangular microstrip patch antennas of frequencies 1.5 GHz and 2.4 GHz are designed and simulated on HFSS

    Microstrip Patch Antenna for GPS Application

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    The study and the design of rectangular microstrip patch antenna for multiband applications are presented in this paper. They can be simulated on antenna design software’s such as High Frequency Simulation Software (HFSS), Advanced Design System Momentum (ADS) and Agilent Vector Network Analyzer (E8361A) where different feeding techniques have been deployed to get the desired results. Two rectangular microstrip patch antennas of frequencies 1.5 GHz and 2.4 GHz are designed and simulated on HFSS

    An electron-deficient triosmium cluster containing the thianthrene ligand: Synthesis, structure and reactivity of [Os₃(CO)₉(μ3-η2-C₁₂H₇S₂)(μ-H)]

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    Reaction of [Os₃(CO)₁₀(CH₃CN)₂] with thianthrene at 80 °C leads to the nonacarbonyl dihydride compound [Os₃(CO)₉(μ-3,4-η²-C₁₂H₆S₂)(μ-H)₂] (1) and the 46-electron monohydride compound [Os₃(CO)₉(μ₃-η²-C₁₂H₇S₂)(μ-H)] (2). Compound 2 reacts reversibly with CO to give the CO adduct [Os₃(CO)₁₀(μ-η²-C₁₂H₇S₂)(μ-H)] (3) whereas with PPh₃ it gives the addition product [Os₃(CO)₉)(PPh₃)(μ-η²-C₁₂H₇S₂)(μ-H)] (4) as well as the substitution product 1,2-[Os₃(CO)₁₀ ((PPh₃)₂] (5) Compound 2 represents a unique example of an electron-deficient triosmium cluster in which the thianthrene ring is bound to cluster by coordination of the sulfur lone pair and a three-center-two-electron bond with the C(2) carbon which bridges the same edge of the triangle as the hydride. Electrochemical and DFT studies which elucidate the electronic properties of 2 are reported

    Farmers’ Perception and Adoption of Agroforestry Practices in Faridpur District of Bangladesh

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    This study mainly focused on exploring perception of farmers' towards agroforestry practices and identifying the demographic factors influencing agroforestry adoption in Faridpur district. Field survey was conducted during November-December, 2016 using semi-structured questionnaire. Multi-stage random sampling was used to select upazillas, unions and villages. Snowball purposive sampling was applied to select 84 respondents in total for the questionnaire survey. Chi-square was used to test variables at 5% level of significance. Homestead agroforestry was found to be the most common agroforestry practice (39.28%), followed by fruit-based agroforestry (21.42%), woodlot plantation (13.09%) and so on. Agroforestry was perceived to increase farm productivity by 82.14% of the respondents, 73.8% opined that agroforestry increase household income, while 30.95% perceived it as a means to food security. On the contrary, 34.52% opined that agroforestry practices decrease cash crops production, 17.85% of the respondents stated agroforestry as a difficult practice. Chi-square test showed no significant association between the adoption of agroforestry practices and respondent's age (P > 0.05) or income range (P > 0.05) of the respondents. On the other hand, there is a positive significant association between the adoption of agroforestry practices and educational level (p< 0.05) as well as the farm size (p< 0.05) of the respondents. The study suggests raising awareness regarding the benefits of agroforestry practices as well as providing technical assistance

    Central Nervous System Depressant, Analgesic and Antidiarrheal Effects of the Seed Extracts of Dimocarpus longan Lour in Rats

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    Purpose: To assess the central nervous system (CNS) depressant, analgesic and antidiarrheal activities of the dried seed crude extracts of Dimocarpus longan Lour in rodents.Methods: Selected pharmacological effects of the ethanol (ENLS), petroleum ether (PELS), chloroform (CHLS) and ethyl acetate (EALS) extracts of D. longan fruit seeds were investigated. CNS depressant activity was evaluated by open field and hole cross tests; analgesic activity by acetic acid-induced writhing test and formalin-induced licking test; and anti-diarrheal activity was assessed in castor oil and magnesium-induced diarrhea rat model. The extracts were given orally in a rat model at doses of 200 and 300 mg/kg body weight. Normal saline served as control in all experiment. In CNS depressant test, diazepam (1 mg/kg) was used as reference drug while indomethacin (10 mg/kg) and loperamide(2 mg/kg) were used as standard drugs in analgesic and antidiarrheal tests, respectively.Results: In hole cross method, EALS showed the most effective depressant effect, viz, 1.17±0.17 for 200 mg/kg dose and 0.83±0.31 number of movements for 300 mg/kg dose after 120 min (p &lt; 0.01), whereas in the open field test, all the extracts exhibited significant (p &lt; 0.01) depressant effect in relation to positive control, diazepam. In acetic acid-induced pain test, PELS gave the lowest number of writhing (2.83±0.307) and the highest inhibition (88.45 %, 300 mg/kg dose) which was statistically significant. All the extracts also significantly (p &lt; 0.01) suppressed licking activity in both phases of the formalin-induced licking test, in contrast to indomethacin. In the antidiarrheal tests, diarrheal suppression was highest at 300 mg/kg dose for all the extracts, compared with loperamide in both castor oil and magnesium sulphate induced diarrhea model.Conclusion: The extracts of Dimocarpus longan tested demonstrated significant CNS depressant, analgesic and antidiarrheal activities in a rodent model.Keywords: Dimocarpus longan Lour, CNS depressant, Analgesic, Anti-diarrheal

    Parental supply of alcohol in childhood and risky drinking in adolescence: Systematic review and meta-analysis

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    © 2017 by the authors. Licensee MDPI, Basel, Switzerland. Whether parental supply of alcohol affects the likelihood of later adolescent risky drinking remains unclear. We conducted a systematic review and meta-analysis to synthesize findings from longitudinal studies investigating this association. We searched eight electronic databases up to 10 September 2016 for relevant terms and included only original English language peer-reviewed journal articles with a prospective design. Two reviewers independently screened articles, extracted data and assessed risk of bias. Seven articles met inclusion criteria, six of which used analytic methods allowing for meta-analysis. In all seven studies, the follow-up period was ≥12 months and attrition ranged from 3% to 15%. Parental supply of alcohol was associated with subsequent risky drinking (odds ratio = 2.00, 95% confidence interval = 1.72, 2.32); however, there was substantial risk of confounding bias and publication bias. In all studies, measurement of exposure was problematic given the lack of distinction between parental supply of sips of alcohol versus whole drinks. In conclusion, parental supply of alcohol in childhood is associated with an increased likelihood of risky drinking later in adolescence. However, methodological limitations preclude a causal inference. More robust longitudinal studies are needed, with particular attention to distinguishing sips from whole drinks, measurement of likely confounders, and multivariable adjustment
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