Semi-Supervised Radio Signal Identification

Radio emitter recognition in dense multi-user environments is an important tool for optimizing spectrum utilization, identifying and minimizing interference, and enforcing spectrum policy. Radio data is readily available and easy to obtain from an antenna, but labeled and curated data is often scarce making supervised learning strategies difficult and time consuming in practice. We demonstrate that semi-supervised learning techniques can be used to scale learning beyond supervised datasets, allowing for discerning and recalling new radio signals by using sparse signal representations based on both unsupervised and supervised methods for nonlinear feature learning and clustering methods

Mechanical properties and chemical stability of pivalolactone-based poly(ether ester)s

The processing, mechanical and chemical properties of poly(ether ester)s, prepared from pivalolactone (PVL), 1,4-butanediol (4G) and dimethyl terephthalate (DMT), were studied. The poly(ether ester)s could easily be processed by injection moulding, owing to their favourable rheological and thermal properties. The tensile response of a poly(ether ester) with a butylene terephthalate (4GT) content of 72 mol%, which exhibited the phenomena of necking and strain-hardening, was related to the morphology of these copolymers. The influence of the short 4G-PVL segments was reflected in a high Young's modulus and yield stress, and resulted in a tough behaviour for the poly(ether ester), with an ultimate elongation of 500%. The poly(ether ester)s were stable towards treatment at room temperature with water or weakly acidic or alkaline solutions. Conditioning at 90°C in water for 264 h resulted in a water uptake of 1 wt%, whereas the rate of hydrolysis was 0.0003 (expressed in An rel h-1) for the poly(ether ester) with a 4GT content of 72 mol%. Although a decay in the mechanical properties for the PVL-based poly(ether ester) after exposure to water at 90°C was observed, these materials were assumed to have a higher hydrolytical stability than other poly(ether ester)

Ageing and Temperature Influence on Polarization/Depolarization Current Behaviour of Paper Immersed in Natural Ester

Transformers play an important role in providing a reliable and efficient electricity supply and are one of the most critical equipments in electric power transmission and distribution systems. The most commonly used liquid in power transformers is mineral oil due to its low price and good properties. However the performance of mineral oil starts to be limited due to environmental consideration [1]. Natural ester insulating fluid offers fire safety, environment and insulation aging advantages over mineral oil and are found to be suitable for the use in transformer insulation system [1]. However, transformer owners require to assess the status of the cellulose insulation in transformer non-destructively. Polarization/depolarization Current (PDC) measurement [2] is one of the non-destructive techniques which have been used to achieve this aim. At the present, there are few publications about the PDC behaviour of natural ester-paper insulation, though the natural ester becomes more widely used in transformers. In this paper, the influence of ageing and temperature on the PDC behaviour of the paper immersed in natural ester and mineral oil were compared. Results show PDC technique can be used to assess the aging condition of the natural-ester paper insulation. The ageing and temperature have similar influence on the PDC behaviour of the paper immersed in natural ester and in mineral oil. The depolarization current of paper immersed in natural ester is lower than that immersed in mineral oil at the same test temperature. The depolarization current of the paper immersed in natural ester and mineral oil increase with the aging time increased. Therefore, the depolarization current can be used to indicate the aging status of natural ester-paper insulation

Credit risk transfers and the macroeconomy : [This Draft: September 2010]

The recent financial crisis has highlighted the limits of the “originate to distribute” model of banking, but its nexus with the macroeconomy and monetary policy remains unexplored. I build a DSGE model with banks (along the lines of Holmström and Tirole [28] and Parlour and Plantin [39] and examine its properties with and without active secondary markets for credit risk transfer. The possibility of transferring credit reduces the impact of liquidity shocks on bank balance sheets, but also reduces the bank incentive to monitor. As a result, secondary markets allow to release bank capital and exacerbate the effect of productivity and other macroeconomic shocks on output and inflation. By offering a possibility of capital recycling and by reducing bank monitoring, secondary credit markets in general equilibrium allow banks to take on more risk. Keywords: Credit Risk Transfer , Dual Moral Hazard , Monetary Policy , Liquidity , Welfare JEL Classification: E3, E5, G3 First Draft: December 2009, This Draft: September 201

Alternating copolyesteramides based on mixtures of 1,4-butyleneterephthalamide and -isophthalamide and ethanediol (4NT/I2)

Alternating copolyesteramides (APEA's) consisting of mixtures of 1,4-butyleneterephthalamide ester (N,N′-bis(p-carbomethoxybenzoyl) diaminobutane) and 1,4-butyleneisophthalamide ester (N,N′-bis(m-carbomethoxybenzoyl) diaminobutane) polymerized with ethanediol were synthesised in an ethanediol solution. The bisesterdiamides were prepared from 1,4-butanediamine and dimethyl terephthalate or dimethylisophthalate respectively. They were analyzed by 1H n.m.r., differential scanning calorimetry (d.s.c.) and high pressure liquid chromatography (h.p.l.c.). The melting behaviour of the copolyesteramides was studied by d.s.c. The dynamic mechanical properties were investigated on injection moulded bars using dynamic mechanical thermal analysis (DMTA). The melting temperature decreased with increasing 1,4-butyleneisophthalamide ester content. The crystallisation rate, the modulus above the glass transition temperature and the glass transition temperature hardly changed. The APEA of 1,4-butyleneisophthalamide ester and ethanediol was amorphous. The lowering of the melting temperature of the copolymers was probably caused by a decrease in lamellar size. The high crystallisation rate and the high physical crosslink density of the copolymers must be ascribed to the presence of 1,4-butyleneterephthalamide ester units which are able to crystallise fast and to form strong crystallites

Descriptors for terpene esters from chromatographic and partition measurements: Estimation of human odor detection thresholds

We have used gas chromatographic retention data together with other data to obtain Abraham descriptors for 30 terpene esters. These include the air-water partition coefficient, as log Kw, for which no experimental values are available for any terpene ester. The other descriptors are the ester dipolarity, S, the hydrogen bond basicity, B, (the ester hydrogen bond acidity is zero for the esters studied), and L the logarithm of the air-hexadecane partition coefficient. Both S and B are larger than those for simple aliphatic esters, as expected from the terpene ester structures that include ring systems and ethylenic double bonds. These descriptors can then be used to obtain a large number of physicochemical and environmental properties of terpene esters. We have analyzed experimental results on human odor detection thresholds and have constructed another equation for the calculation of these thresholds, to go with a previous equation that we have reported. Then the descriptors for terpene esters can be used to estimate the important odor detection thresholds

Highly Diastereo- and Enantioselective Allylboration of Aldehydes using alpha-Substituted Allyl/Crotyl Pinacol Boronic Esters via in Situ Generated Borinic Esters

Readily available, alpha-substituted allyl/crotyl pinacol boronic esters often give low E/Z selectivity (with Z favored) in reactions with aldehydes. We found that addition of nBuLi to the pinacol boronic ester followed by trapping of the alkoxide with TFAA leads to an intermediate allyl borinic ester which undergoes allylboration with very high E selectivity. The substrate scope includes primary to tertiary alkyl alpha-substituents, crotyl substrates, and the previously unreported beta-methallyl pinacol boronic esters. The latter give very high Z selectivity under standard conditions which is completely reversed to high E selectivity under the new conditions. Monitoring the reaction by B-11 NMR confirmed that the reaction proceeds through a borinic ester intermediate.</p

Three protected tetrapeptides

The structures of three protected tetrapeptides, containing the Boc-Gly-Gly-Phe-X-OMe chain, tert-butoxycarbonyl-glycy-glycl-phenylalanine-leucine methyl ester dihydrate, Boc-Gly-Gly-L-Phe-D-Leu-OMe, C25H38N4O7·2H2O, tert-butoxycarbonyl-glycy-glycl-phenylalanine-methionine methyl ester dihydrate, Boc-Gly Gly-L-Phe-D-Met-OMe, C24H36N4O7S.2H2O and tert-butoxycarbonyl-glycy-glycl-phenylalanine-norleucine methyl ester dihydrate, Boc-Gly-Gly-D-Phe-L-Nle-OMe, C25H38N4O7.2H2O, are described. The three molecules have the same conformation of the Boc-Gly Gly Phe-X-OMe tetrapeptide chain and display the same packing, consisting of couples of molecules linked head-to-tail by two hydrogen (N-HO) bonds; other hydrogen bonds, also involving two water molecules of crystallization, link these couples together, and give rise to a planar structure

Monetary policy in a world with different financial systems

Major currency areas are characterized by important differences in financial structure that are clear in microeconomic data. Surprisingly, this fact is seldom discussed in the analysis of the international transmission of shocks. This paper attempts to fill the gap. First, I show some stylized facts about financial differences and cyclical correlations among the main OECD countries. Second, using a two-country model with monopolistic competition and sticky prices, calibrated to US and euro area data, I analyze the international transmission of shocks with different degrees of financial fragility in the two economies. I find, first, that financial diversity can account for heterogenous business cycle fluctuations. Differential responses to shocks are shown to occur with independent monetary policies - Taylor rules or rigid inflation targets - even with low degrees of economic and financial openness. Credible pegs help to increase the synchronization of cycles. Secondly, differences in persistence of the interest rates help to explain high persistence in the real exchange rate. Finally, weak financial systems can result in large welfare losses under symmetric and correlated shocks. JEL Classification: E3, E42, E44, E52, F41differential transmission mechanism, Financial diversity, financial stability, monetary regimes, welfare losses