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High performance IP core for HEVC quantization

Publication . Dias, Tiago; Roma, Nuno; Sousa, Leonel

A new class of quantization architectures suitable for the realization of high performance and hardware efficient forward, inverse and unified quantizers for HEVC is presented. The proposed structures are based on a highly flexible and optimized integer datapath that can be configured to provide several pipelined and non-pipelined implementations, offering distinct trade-offs between performance and hardware cost, which makes them highly suitable for most video coding application domains. The experimental results obtained using a 90 nm CMOS process show that the proposed class of quantization architectures is able to process 4k UHDTV video sequences in real-time (3840 x 2160 @ 30fps), with a power consumption as low as 3.9 mW when the unified architecture is operated at 374 MHz.

2015-07-30Conference object

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Volatility spillovers in the Iberian electricity market

Publication . Vicente, João; Martins, Ana Alexandra; Lagarto, João; Sousa, Jorge A. M.

With the globalization of the world economy, the relationships between commodities, financial and other markets are relevant. Although the electricity market is a more recent kind of market, it is still related with other markets, such as, commodities markets (natural gas, coal, oil), and carbon emissions markets. In this work, we propose to study the interconnections between the day-ahead Iberian electricity market (MIBEL) and the commodities markets, as well as, the carbon emissions markets between 2010 and 2016. To achieve this purpose, we use the Diebold-Yilmaz framework, which proposes measures of the interdependence of returns and volatilities through variance decomposition of forecasted error variances in a generalized vector autoregressive model. Results show that the markets that had a higher influence in MIBEL in the analyzed period were the TTF and Zeebrugge natural gas markets and the markets that MIBEL most influenced were the Coal (API2) and CER market.

2017-06Conference object

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Fault tolerance capability and semiconductor's hold-off voltage of solid-state bipolar Marx modulators

Publication . Canacsinh, Hiren; Silva, Fernando; Luis Redondo

Two solid-state bipolar Marx modulators are analyzed and compared regarding hold-off semiconductor voltages and open-fault tolerance capability. Normal and abnormal operating conditions are considered, such as switch synchronization mismatches, failures, and open faults. Ten-stage laboratory prototypes of two bipolar Marx modulators have been assembled using 1200-V insulated gate bipolar transistors and matching diodes, to operate at 500-V dc input voltage. Outputs are 4-kV bipolar pulses, 1% duty ratio, into resistive loads, and 1-kHz frequency. Lack of synchronization and open-fault tests confirm that only topologies with redundant switches can operate without semiconductors being subjected to double hold-off voltages while presenting current paths to clear faults.

2017-10Conference object

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Modeling maximum day-ahead market price using circular statistical methods

Publication . Martins, Ana Alexandra; Lagarto, João; Sousa, Jorge A. M.

Electricity day-ahead market price and traded quantity present a distinct pattern between peak and off-peak hours, following a pattern that tends to repeat over a 24-hour time cycle. The cyclic nature of these variables enables the use of circular statistics. Circular statistics is a set of techniques for modelling the random nature of directional data, which are typically expressed as angular measurements, which can be used to analyze any kind of data that are cyclic in nature, such as time-of-day data measured on a 24h clock. In this study, the circular statistical methods are used for analyzing the maximum values of day-ahead market price in the Iberian Electricity Market (MIBEL). The data considered in this study refer to the hourly price of electricity observed in the MIBEL, for Portugal and Spain. Also, variables that have influence on the electricity market prices such as demand, production by technology, namely hydro, coal, CCGT and Special Regime Production (production from CHP, wind, photovoltaic, small hydro, etc.) and the strategic behavior of market participants are also analyzed using circular statistics methods. The analysis performed allowed to conclude that circular statistical methods are a powerful tool to understand market price behavior.

2017Conference object

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Reversible current power supply for fast-field cycling nuclear magnetic resonance equipment

Publication . Lima, Marco; Sousa, Duarte M.; Roque, António; Margato, Elmano

The Fast Field-Cycling Nuclear Magnetic Resonance (FFC-NMR) is a technique used to study the molecular dynamics of different types of materials. The main elements of this equipment are a magnet and its power supply. The magnet used as reference in this work is basically a ferromagnetic core with two sets of coils and an air-gap where the materials' sample is placed. The power supply should supply the magnet being the magnet current controlled in order to perform cycles. One of the technical issues of this type of solution is the compensation of the non-linearities associated to the magnetic characteristic of the magnet and to parasitic magnetic fields. To overcome this problem, this paper describes and discusses a solution for the FFC-NMR power supply based on a four quadrant DC/DC converter.

2015Conference object

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