578 research outputs found
Collective oscillations in quantum rings: a broken symmetry case
We present calculations within density functional theory of the ground state
and collective electronic oscillations in small two-dimensional quantum rings.
No spatial symmetries are imposed to the solutions and, as in a recent
contribution, a transition to a broken symmetry solution in the intrinsic
reference frame for an increasingly narrow ring is found. The oscillations are
addressed by using real-time simulation. Conspicuous effects of the broken
symmetry solution on the spectra are pointed out.Comment: ReVTeX, 5 embedded eps, two gifs. Accepted in EPJ
Investment needs for irrigation infrastructure along different socio-economic pathways
This paper conducts an assessment of the global costs for expanding, upgrading, and improving irrigation infra-structure in developing countries, along different future scenarios toward 2050. It uses the GLobal BIOsphere Man-agement Model, a partial equilibrium model of the global agricultural and forestry sectors. It examines the impacts of irrigation expansion on the agriculture and food system, from the perspective of different Sustainable Development Goals, in particular food security (goal 2), land use change and biodiversity (goal 15), greenhouse gas emissions (goal 13), and sustainable water use (goal 6). It finds that irriga-tion support policies improve food security globally and can reduce the burden on land by limiting expansion of cropland area. However, the effectiveness of irrigation to achieve a larger set of goals depends on the regional con-text. In South Asia and the Middle East and North Africa, the expansion of irrigation increases unsustainable water extraction practices. A sensitivity analysis is conducted to evaluate the uncertainty of the infrastructure costs and impacts under different socioeconomic developments, levels of radiative forcing and climate change scenarios, dietary patterns, trade openness, and efficiencies of irriga-tion systems. The findings indicate that irrigation systems could play an important role in adaptation to the most adverse climate change; however, increased water scarcity may also limit adaptation potentials
African Livestock Futures: Realizing the potential of livestock for food security, poverty reduction and the environment in Sub-Saharan Africa
Briquetagem de biomassa florestal: variáveis do processo e qualidade do produto.
EVINCI. Resumo
L’avenir de l’élevage africain : Réaliser le potentiel de l’élevage pour la sécurité alimentaire, la réduction de la pauvreté et la protection de l’environnement en Afrique sub- saharienne
NoLACE: Improving Low-Complexity Speech Codec Enhancement Through Adaptive Temporal Shaping
Speech codec enhancement methods are designed to remove distortions added by
speech codecs. While classical methods are very low in complexity and add zero
delay, their effectiveness is rather limited. Compared to that, DNN-based
methods deliver higher quality but they are typically high in complexity and/or
require delay. The recently proposed Linear Adaptive Coding Enhancer (LACE)
addresses this problem by combining DNNs with classical long-term/short-term
postfiltering resulting in a causal low-complexity model. A short-coming of the
LACE model is, however, that quality quickly saturates when the model size is
scaled up. To mitigate this problem, we propose a novel adatpive temporal
shaping module that adds high temporal resolution to the LACE model resulting
in the Non-Linear Adaptive Coding Enhancer (NoLACE). We adapt NoLACE to enhance
the Opus codec and show that NoLACE significantly outperforms both the Opus
baseline and an enlarged LACE model at 6, 9 and 12 kb/s. We also show that LACE
and NoLACE are well-behaved when used with an ASR system.Comment: submitted to ICASSP 202
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