A 10 Mb/s visible light communication system using a low bandwidth polymer light-emitting diode

In this paper we experimentally demonstrate a 10 Mb/s error free visible light communications (VLC) system using polymer light-emitting diodes (PLEDs) for the first time. The PLED under test is a blue emitter with ∼600 kHz bandwidth. Having such a low bandwidth means the introduction of an intersymbol interference (ISI) induced penalty at higher transmission speeds and thus the requirement for an equalizer. In this work we improve on previous literature by implementing a decision feedback equalizer, rather than a linear equalizer. Considering 7% and 20% forward error correction codes, transmission speeds up to ∼12 Mb/s can be supported.

Optimising market share and profit margin:SMDP-based tariff pricing under the smart grid paradigm

Smart grid technologies have given rise to a liberalised and decentralised electricity market, enabling energy providers and retailers to have a better understanding of the demand side and its response to pricing signals. This paper puts forward a reinforcement-learning-powered tool aiding an electricity retailer to define the tariff prices it offers, in a bid to optimise its retail strategy. In a competitive market, an energy retailer aims to simultaneously increase the number of contracted customers and its profit margin. We have abstracted the problem of deciding on a tariff price as faced by a retailer, as a semi-Markov decision problem (SMDP). A hierarchical reinforcement learning approach, MaxQ value function decomposition, is applied to solve the SMDP through interactions with the market. To evaluate our trading strategy, we developed a retailer agent (termed AstonTAC) that uses the proposed SMDP framework to act in an open multi-agent simulation environment, the Power Trading Agent Competition (Power TAC). An evaluation and analysis of the 2013 Power TAC finals show that AstonTAC successfully selects sell prices that attract as many customers as necessary to maximise the profit margin. Moreover, during the competition, AstonTAC was the only retailer agent performing well across all retail market settings.

Revealing statistical properties of quasi-CW fibre lasers in bandwidth-limited measurements

We introduce a general technique how to reveal in experiments of limited electrical bandwidth which is lower than the optical bandwidth of the optical signal under study, whether the statistical properties of the light source obey Gaussian distribution or mode correlations do exist. To do that one needs to perform measurements by decreasing the measurement bandwidth. We develop a simple model of bandwidth-limited measurements and predict universal laws how intensity probability density function and intensity auto-correlation function of ideal completely stochastic source of Gaussian statistics depend on limited measurement bandwidth and measurement noise level. Results of experimental investigation are in good agreement with model predictions. In particular, we reveal partial mode correlations in the radiation of quasi-CW Raman fibre laser.

Influence of the generated power, measurement bandwidth, and noise level on intensity statistics of a quasi-CW Raman fiber laser

In the present paper we numerically study instrumental impact on statistical properties of quasi-CW Raman fiber laser using a simple model of multimode laser radiation. Effects, that have the most influence, are limited electrical bandwidth of measurement equipment and noise. To check this influence, we developed a simple model of the multimode quasi- CW generation with exponential statistics (i.e. uncorrelated modes). We found that the area near zero intensity in probability density function (PDF) is strongly affected by both factors, for example both lead to formation of a negative wing of intensity distribution. But far wing slope of PDF is not affected by noise and, for moderate mismatch between optical and electrical bandwidth, is only slightly affected by bandwidth limitation. The generation spectrum often becomes broader at higher power in experiments, so the spectral/electrical bandwidth mismatch factor increases over the power that can lead to artificial dependence of the PDF slope over the power. It was also found that both effects influence the ACF background level: noise impact decreases it, while limited bandwidth leads to its increase. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Pulse generation without gain-bandwidth limitation in a laser with self-similar evolution

With existing techniques for mode-locking, the bandwidth of ultrashort pulses from a laser is determined primarily by the spectrum of the gain medium. Lasers with self-similar evolution of the pulse in the gain medium can tolerate strong spectral breathing, which is stabilized by nonlinear attraction to the parabolic self-similar pulse. Here we show that this property can be exploited in a fiber laser to eliminate the gain-bandwidth limitation to the pulse duration. Broad (∼200 nm) spectra are generated through passive nonlinear propagation in a normal-dispersion laser, and these can be dechirped to ∼20-fs duration. © 2012 Optical Society of America.

Option Pricing by Branching Process

2000 Mathematics Subject Classification: 60J80, 62P05.

Bandwidth programmable optical Nyquist pulse generation in passively mode-locked fiber laser

We propose and numerically demonstrate a novel simple method to produce optical Nyquist pulses based on pulse shaping in a passively mode-locked fiber laser with an in-cavity flat-top spectral filter. The proposed scheme takes advantage of the nonlinear in-cavity dynamics of the laser and offers the possibility to generate high-quality sinc-shaped pulses with widely tunable bandwidth directly from the laser oscillator. We also show that the use of a filter with a corrective convex profile relaxes the need for large nonlinear phase accumulation in the cavity by offsetting the concavity of the nonlinearly broadened pulse spectrum.

Nonstandard Finite Difference Schemes with Application to Finance: Option Pricing

2000 Mathematics Subject Classification: 65M06, 65M12.

Mode-locked fiber laser without gain-bandwidth limitation

We show that self-similar evolution in a fiber laser can stabilize spectra broader than the gain bandwidth. 21-fs pulses, which are the shortest from a fiber laser to date, and 200-nm spectra are generated. © OSA 2012.

A származtatott termékek árazása és annak problémái az egyensúlyelmélet szempontjából (Pricing of derived products and problems with it in terms of equilibrium theory)

A szerző röviden összefoglalja a származtatott termékek árazásával kapcsolatos legfontosabb ismereteket és problémákat. A derivatív árazás elmélete a piacon levő termékek közötti redundanciát kihasználva próbálja meghatározni az egyes termékek relatív árát. Ezt azonban csak teljes piacon lehet megtenni, és így csak teljes piac esetén lehetséges a hasznossági függvények fogalmát az elméletből és a ráépülő gyakorlatból elhagyni, ezért a kockázatsemleges árazás elve félrevezető. Másképpen fogalmazva: a származtatott termékek elmélete csak azon az áron képes a hasznossági függvény fogalmától megszabadulni, ha a piac szerkezetére a valóságban nem teljesülő megkötéseket tesz. Ennek hangsúlyozása mind a piaci gyakorlatban, mind az oktatásban elengedhetetlen. / === / The author sums up briefly the main aspects and problems to do with the pricing of derived products. The theory of derivative pricing uses the redundancy among products on the market to arrive at relative product prices. But this can be done only on a complete market, so that only with a complete market does it become possible to omit from the theory and the practice built upon it the concept of utility functions, and for that reason the principle of risk-neutral pricing is misleading. To put it another way, the theory of derived products is capable of freeing itself from the concept of utility functions only at a price where in practice it places impossible restrictions on the market structure. This it is essential to emphasize in market practice and in teaching.

Válság és hitelderivatívák. A szintetikus fedezett adósságkötelezettségek (CDO-k) árazása és kockázataik (Crisis and loan derivatives. The pricing and risks of synthetic collateralized debt obligations)

A dolgozat első részében röviden áttekintjük a 2007-ben kezdődött pénzügyi válság lefolyását és a válsághoz vezető okokat. A bemutatás során igyekszünk végig a mögöttes folyamatokra és azok mozgatórugóira koncentrálni, ezzel megragadva a válság egyfajta "elméletét". A bemutatásból láthatóvá válik a hitelderivatívák kiemelt szerepe a válság során. A dolgozat második részében az egyik legnépszerűbb hitelderivatív termék, a szintetikus fedezett adósságkötelezettségek (CDO-k) matematikai modellezését és annak problémáit mutatjuk be. Sokak szerint ezek a matematikai modellek okozták - vagy legalábbis felerősítették - a válságot. Az elemzés során megmutatjuk, hogy nemcsak a modellezési eszközök nem voltak megfelelők, hanem az árazás elve sem állta meg a helyét a kockázatsemleges árazási keretben. Ez az eredmény élesen rámutat a mögöttes elméletek válságára. / === / The first part of the paper examines briefly the financial crisis of 2007 and its causes, focusing on its driving processes and key motifs. This shows clearly the importance and centrality of credit derivatives in the crisis. The second part presents a mathematical modelling of one of the most popular credit derivative products: synthetic collateralized debt obligations, along with the drawbacks and problems of the modelling process. It is widely claimed that these products caused or at least precipitated the crises. The authors show not only that the modelling tools were inappropriate, but that the principle for pricing did not match adequately the risk-neutral valuation framework.

A vállalatok árképzési gyakorlata a versenyképesség szolgálatában (The pricing practice of corporates and the competitiveness)

A marketing-szakirodalom szerint az ár az egyik legfontosabb marketingeszköz, és a vállalati versenyképesség értelmezésében is meghatározó szerepe van. A megfelelő árképzés kialakítása ugyanakkor összetett folyamat, amely önmagában is külön képességnek tekinthető, és kell befektetést igényel. A szerző az elemzés során így arra volt kíváncsi, hogy a vezető, azaz a versenyképes vállalatok árazási gyakorlata mutat-e eltéréseket, és, ha igen, melyek azok a területek, amelyek leginkább összefüggnek az eredményességükkel. A háromszáz hazai vállalatra kiterjedő kutatás során azt találta, hogy a vezető vállalatok valamelyest másképp tekintenek az ár szerepére és szignifikánsan magasabb árszínvonalon értékesítenek. Ez nagyobb mozgásteret enged számukra, a versenytársak árkihívásaira így könnyebben tudnak árakciókkal válaszolni. Árképzési céljaikban azonban kevésbé mutatkoznak különbségek, mert számukra is kihívást jelent a válság, és nekik is több szempontnak kell egyszerre megfelelniük. Az árak meghatározásánál azonban több tényezőt vesznek figyelembe és jobban támaszkodnak a vevőkről szerzett információkra. ______________ According to the marketing literature the price is one of the most important marketing tools and it plays a dominant role in the interpretation of corporate competitiveness, as well. The appropriate pricing, however, a complex process that can be regarded as a distinct capability and it requires sufficient investment itself. In this analysis the author enquired if the pricing practice of the leading, that is, the most competitive companies has a different profile, and if yes, which areas are associated with the success of them. Based on the survey of 300 domestic organisations he found that the leading companies consider the role of price in a slightly different way and they price their products or services significantly higherthan the others. This let them some space to manoeuvre and they can react with price promotions when the competitors challenge them with price activities. Regarding the pricing objectives the author couldn’t identify differences. The leading companies are also affected by the economic crisis and they have to match many expectations at the same time but they take more factors into consideration when they set their prices and more likely use customer information.

Carbon pricing: theory and practice

Carbon pricing policy is a fundamental humanly devised theoretical and practical cornerstone in the fight against climate change. It involves short term and long term policies, theoretical and practical considerations. A quantitative global stabilisation target range for the stock of greenhouse gases in the atmosphere is needed, because it is an important and useful foundation in the shaping of a comprehensive climate pricing policy. A global stabilisation target range is obviously a long term policy to control climate change and events ensuing excessive increase in temperature. Setting long term objectives in the fight against climate change are substantial in avoiding catastrophic consequences therefore short term policies, which aim advances in emission reductions, have to be consistent with the pre-defined long term stabilisation goals. Short term policy reaction means using price-driven instruments like taxes and tradable quotas. These instruments allow broad flexibility in the parameters of emission reduction, and provide opportunities and incentives wherewith the cost of mitigation and abatement can be kept down. Taxes and tradable quotas give the flexibility in how, where and when emission reduction can be accomplished thereby reaching agreements between states and companies may result an appropriate and environment-conscious emission scheme, that can fit into the long term objectives.