En la era de los contenidos digitales: nuevos modelos de negocio para la prensa

Partiendo del reconocimiento de los cambios producidos por el marco digital y por otros elementos del entorno en la cadena de valor del negocio de la prensa, se esboza una propuesta de modelo de negocio sostenible, en el marco de la prestación de servicios a la sociedad.This author acknowledges changes brought about by digital supports and other components in the media industry's value chain. In response to this, a sustainable business model is sketched out, focusing on services offered to societ

SUSCEPTIBILITY OF 7 CULTIVARS OF COFFEA ARABICA L. TO LEUCOPTERA COFFEELLA (GUÉRIN-MÉNEVILLE)

SUSCEPTIBILITY OF 7 CULTIVARS OF COFFEA ARABICA L. TO LEUCOPTERA COFFEELLA (GUÉRIN-MÉNEVILLE

Recognizing Voice Over IP: A Robust Front-End for Speech Recognition on the World Wide Web

The Internet Protocol (IP) environment poses two relevant sources of distortion to the speech recognition problem: lossy speech coding and packet loss. In this paper, we propose a new front-end for speech recognition over IP networks. Specifically, we suggest extracting the recognition feature vectors directly from the encoded speech (i.e., the bit stream) instead of decoding it and subsequently extracting the feature vectors. This approach offers two significant benefits. First, the recognition system is only affected by the quantization distortion of the spectral envelope. Thus, we are avoiding the influence of other sources of distortion due to the encoding-decoding process. Second, when packet loss occurs, our front-end becomes more effective since it is not constrained to the error handling mechanism of the codec. We have considered the ITU G.723.1 standard codec, which is one of the most preponderant coding algorithms in voice over IP (VoIP) and compared the proposed front-end with the conventional approach in two automatic speech recognition (ASR) tasks, namely, speaker-independent isolated digit recognition and speaker-independent continuous speech recognition. In general, our approach outperforms the conventional procedure, for a variety of simulated packet loss rates. Furthermore, the improvement is higher as network conditions worsen.Publicad

Robust energy system planning for decarbonization under technological uncertainty: From transport electrification to power system investments

This work develops energy system modeling tools that identify features of a robust energy policy: a policy that performs well relative to alternatives. The tools are based on the Open Souce Modeling System (OSeMOSYS), are named the Multipurpose OSeMOSYS-based Framework (MOMF), and are applied to Costa Rica´s energy transition through the lens of its National Decarbonization Plan (NDP). The MOMF can support energy decarbonization planning exercises, and it is suitable to address the uncertainty involved in a decades-long process. It compares possible NDP futures -quantitative combinations of uncertainties and sectoral policy objectives- to a business-as-usual (BAU) scenario without decarbonization. The MOMF also evaluates actors within a country, including the fiscal impacts of decarbonization, following the best practices of applied energy modeling for policy support. This work finds that the NDP has high economic benefits (avoided costs relative to the BAU) in the long term, equivalent to 5.5% of GDP yearly in the 2041-2050 decade. In 2031-2040, the benefits are 0.8% of GDP yearly; in 2022-30, the NDP faces net costs (more costs than the BAU) of 0.9% of GDP yearly. These results are averages across futures and can be higher or lower. The government will have lower direct tax revenue of about 0.87% of GDP yearly in 2041-2050 and will need to redistribute benefits to compensate for this. It can use vehicle-kilometer taxes (VKT), property taxes, or energy taxes for the redistribution, mainly taxing private transport owners -who have the highest benefits-. However, to facilitate the decarbonization of freight firms in 2022-2030 and 2031-2040, the government could subsidize their zero-emission vehicles (ZEV) adoption. High benefits, low emissions complying with net-zero targets, and low electricity and public transport prices are desirable policy outcomes. Low costs for ZEVs and energy infrastructure -including renewables and storage- are crucial uncertain conditions for desirable outcomes. The robust levers the government can adopt to achieve desirable outcomes must decouple economic growth from transport activity. The specific levers include public transport investments, digitalization, non-motorized transport, ride-sharing, logistics hubs, and city densification. Moreover, low electricity prices need a low cost of capital to finance investments in the power sector.UCR::Vicerrectoría de Investigación::Sistema de Estudios de Posgrado::Ingeniería::Maestría Académica en Ingeniería Eléctric

Origin and Sustainability of The Population of Asteroids Captured in the Exterior Resonance 1:2 with Mars

At present, approximately 1500 asteroids are known to evolve inside or sticked to the exterior 1:2 resonance with Mars at a = 2.418 AU, being (142) Polana the largest member of this group. The effect of the forced secular modes superposed to the resonance gives rise to a complex dynamical evolution. Chaotic diffusion, collisions, close encounters with massive asteroids and mainly orbital migration due to the Yarkovsky effect generate continuous captures to and losses from the resonance, with a fraction of asteroids remaining captured over long time scales and generating a concentration in the semimajor axis distribution that exceeds by 20% the population of background asteroids. The Yarkovsky effect induces different dynamics according to the asteroid size, producing an excess of small asteroids inside the resonance. The evolution in the resonance generates a signature on the orbits, mainly in eccentricity, that depends on the time the asteroid remains captured inside the resonance and on the magnitude of the Yarkovsky effect. The greater the asteroids, the larger the time they remain captured in the resonance, allowing greater diffusion in eccentricity and inclination. The resonance generates a discontinuity and mixing in the space of proper elements producing misidentification of dynamical family members, mainly for Vesta and Nysa-Polana families. The half-life of resonant asteroids large enough for not being affected by the Yarkovsky effect is about 1 Gyr. From the point of view of taxonomic classes, the resonant population does not differ from the background population and the excess of small asteroids is confirmed.Comment: Accepted for publication in Icaru

A Comparison of Front-Ends for Bitstream-Based ASR over IP

Automatic speech recognition (ASR) is called to play a relevant role in the provision of spoken interfaces for IP-based applications. However, as a consequence of the transit of the speech signal over these particular networks, ASR systems need to face two new challenges: the impoverishment of the speech quality due to the compression needed to fit the channel capacity and the inevitable occurrence of packet losses. In this framework, bitstream-based approaches that obtain the ASR feature vectors directly from the coded bitstream, avoiding the speech decoding process, have been proposed ([S.H. Choi, H.K. Kim, H.S. Lee, Speech recognition using quantized LSP parameters and their transformations in digital communications, Speech Commun. 30 (4) (2000) 223–233. A. Gallardo-Antolín, C. Pelàez-Moreno, F. Díaz-de-María, Recognizing GSM digital speech, IEEE Trans. Speech Audio Process., to appear. H.K. Kim, R.V. Cox, R.C. Rose, Performance improvement of a bitstream-based front-end for wireless speech recognition in adverse environments, IEEE Trans. Speech Audio Process. 10 (8) (2002) 591–604. C. Peláez-Moreno, A. Gallardo-Antolín, F. Díaz-de-María, Recognizing voice over IP networks: a robust front-end for speech recognition on the WWW, IEEE Trans. Multimedia 3(2) (2001) 209–218], among others) to improve the robustness of ASR systems. LSP (Line Spectral Pairs) are the preferred set of parameters for the description of the speech spectral envelope in most of the modern speech coders. Nevertheless, LSP have proved to be unsuitable for ASR, and they must be transformed into cepstrum-type parameters. In this paper we comparatively evaluate the robustness of the most significant LSP to cepstrum transformations in a simulated VoIP (voice over IP) environment which includes two of the most popular codecs used in that network (G.723.1 and G.729) and several network conditions. In particular, we compare ‘pseudocepstrum’ [H.K. Kim, S.H. Choi, H.S. Lee, On approximating Line Spectral Frequencies to LPC cepstral coefficients, IEEE Trans. Speech Audio Process. 8 (2) (2000) 195–199], an approximated but straightforward transformation of LSP into LP cepstral coefficients, with a more computationally demanding but exact one. Our results show that pseudocepstrum is preferable when network conditions are good or computational resources low, while the exact procedure is recommended when network conditions become more adverse.Publicad

Band-pass filtering of the time sequences of spectral parameters for robust wireless speech recognition

In this paper we address the problem of automatic speech recognition when wireless speech communication systems are involved. In this context, three main sources of distortion should be considered: acoustic environment, speech coding and transmission errors. Whilst the first one has already received a lot of attention, the last two deserve further investigation in our opinion. We have found out that band-pass filtering of the recognition features improves ASR performance when distortions due to these particular communication systems are present. Furthermore, we have evaluated two alternative configurations at different bit error rates (BER) typical of these channels: band-pass filtering the LP-MFCC parameters or a modification of the RASTA-PLP using a sharper low-pass section perform consistently better than LP-MFCC and RASTA-PLP, respectively.Publicad

HOST INSTAR PREFERENCE OF MIRAX INSULARIS (MUESEBECK) (HYMENOPTERA: BRACONIDAE), A KOINOBIONT PARASITOID OF LEUCOPTERA COFFEELLA GUERIN-MÉNÉVILLE (LEPIDOPTERA: LYONETIIDAE)

HOST INSTAR PREFERENCE OF MIRAX INSULARIS (MUESEBECK) (HYMENOPTERA: BRACONIDAE), A KOINOBIONT PARASITOID OF LEUCOPTERA COFFEELLA GUERIN-MÉNÉVILLE (LEPIDOPTERA: LYONETIIDAE

Implementación de balastro con corrección de factor de potencia pasivo

En este documento se analiza funcionamiento de los balastros como fuente de alimentación de lámpara de gases, así como sus diferentes topologías, magnéticas y electrónicas, y la necesidad de usar circuitos de corrección de factor de potencia y disminución de distorsón por armónicos, THD. También se analizó el comportamiento de un balastro ante diferentes etapas de corrección de factor de potencia usando simuladores computacionales como el PSPICE con bases de diseño en un prototipo