463 research outputs found
GW26-e3571 Echocardiographic Diagnosis of Rare Pathological Patterns of Sinus of Valsalva Aneurysm
Ecology of Yuqing County Carbon Sink Calculation and Ecosystem Protection Measures
Based on the remote sensing statistical data of land use of terrestrial ecosystems in Yuqing County, this paper calculates the amount of carbon sinks in the county according to the existing carbon sink carbon density index, compares the amount of different types of carbon sinks, and analyzes their respective carbon sink potential. The results show that the forest carbon sink is the largest, about 2.2 million tons, accounting for 75% of the total carbon sink in the county, showing the great potential of forest vegetation to absorb CO2 through photosynthesis, followed by the carbon sink produced by dry land (cultivated land), about 400,000 tons, accounting for 13% of the total carbon sink in the county; Although the amount of wetland aquatic carbon sink is small, its carbon density is very large, and it has the advantages of short renewal time and fast carbon sink, so it has great potential and can be artificially regulated to increase carbon sink. Based on the above research and analysis, combined with the spirit of the national carbon peak and carbon neutral policy and the natural law of ecosystem development, three measures to protect and increase carbon sinks in terrestrial ecosystems were put forward: (1) continuing to carry out forestry planting and do a good job in forestry protection; (2) stabilizing the surface water area and developing aquatic carbon sinks; (3) Establish a long-term monitoring system to ensure the contribution of carbon sinks, provide support for the protection of ecosystem and the development of carbon sink potential in Yuqing County from two aspects of science and management, and compare the amount of different types of carbon sinks, and analyze their carbon sink potential. On this basis, combined with the spirit of the national carbon peak and carbon neutral policy and the natural law of ecosystem development, three kinds of terrestrial ecosystem carbon sink protection and increase wording were put forward accordingly, which provided support for ecosystem protection and carbon sink potential development in Yuqing County from two aspects of science and management
Negative electrocaloric effect in nonpolar phases of perovskite over wide range of temperature
The electrocaloric effect (ECE) offers a promising alternative to the
traditional gas compressing refrigeration due to its high efficiency and
environmental friendliness. The unusual negative electrocaloric effect refers
to the adiabatic temperature drops due to application of electric field, in
contrast with the normal (positive) ECE, and provides ways to improve the
electrocaloric efficiency in refrigeration cycles. However, negative ECE is
unusual and requires a clear understanding of microscopic mechanisms. Here, we
found unexpected and extensive negative ECE in nonpolar orthorhombic,
tetragonal, and cubic phases of halide and oxide perovskite at wide range of
temperature by means of first-principle-based large scale Monte Carlo methods.
Such unexpected negative ECE originates from the octahedral tilting related
entropy change rather than the polarization entropy change under the
application of electric field. Furthermore, a giant negative ECE with
temperature change of 8.6 K is found at room temperature. This giant and
extensive negative ECE in perovskite opens up new horizon in the research of
caloric effects and broadens the electrocaloric refrigeration ways with high
efficiency.Comment: 11 pages, 7 figure
HpGAN: Sequence Search with Generative Adversarial Networks
Sequences play an important role in many engineering applications and
systems. Searching sequences with desired properties has long been an
interesting but also challenging research topic. This article proposes a novel
method, called HpGAN, to search desired sequences algorithmically using
generative adversarial networks (GAN). HpGAN is based on the idea of zero-sum
game to train a generative model, which can generate sequences with
characteristics similar to the training sequences. In HpGAN, we design the
Hopfield network as an encoder to avoid the limitations of GAN in generating
discrete data. Compared with traditional sequence construction by algebraic
tools, HpGAN is particularly suitable for intractable problems with complex
objectives which prevent mathematical analysis. We demonstrate the search
capabilities of HpGAN in two applications: 1) HpGAN successfully found many
different mutually orthogonal complementary code sets (MOCCS) and optimal
odd-length Z-complementary pairs (OB-ZCPs) which are not part of the training
set. In the literature, both MOCSSs and OB-ZCPs have found wide applications in
wireless communications. 2) HpGAN found new sequences which achieve four-times
increase of signal-to-interference ratio--benchmarked against the well-known
Legendre sequence--of a mismatched filter (MMF) estimator in pulse compression
radar systems. These sequences outperform those found by AlphaSeq.Comment: 12 pages, 16 figure
Congenital right subclavian artery-superior vena cava fistula recognized by transthoracic echocardiography
Coefficient of performance at maximum figure of merit and its bounds for low-dissipation Carnot-like refrigerators
The figure of merit for refrigerators performing finite-time Carnot-like
cycles between two reservoirs at temperature and () is
optimized. It is found that the coefficient of performance at maximum figure of
merit is bounded between 0 and for the
low-dissipation refrigerators, where is the
Carnot coefficient of performance for reversible refrigerators. These bounds
can be reached for extremely asymmetric low-dissipation cases when the ratio
between the dissipation constants of the processes in contact with the cold and
hot reservoirs approaches to zero or infinity, respectively. The observed
coefficients of performance for real refrigerators are located in the region
between the lower and upper bounds, which is in good agreement with our
theoretical estimation.Comment: 5 journal pages, 3 figure
Assessment of the spatial and temporal variations of water quality for agricultural lands with crop rotation in China by using a HYPE model
Many water quality models have been successfully used worldwide to predict nutrient losses from anthropogenically impacted catchments, but hydrological and nutrient simulations with little data are difficult considering the transfer of model parameters and complication of model calibration and validation. This study aims (i) to assess the performance capabilities of a new and relatively more advantageous model-hydrological predictions for the environment (HYPE) to simulate stream flow and nutrient load in ungauged agricultural areas by using a multi-site and multi-objective parameter calibration method and (ii) to investigate the temporal and spatial variations of total nitrogen (TN) and total phosphorous (TP) concentrations and loads with crop rotation using the model for the first time. A parameter estimation tool (PEST) was used to calibrate parameters, which shows that the parameters related to the effective soil porosity were most sensitive to hydrological modeling. N balance was largely controlled by soil denitrification processes, whereas P balance was influenced by the sedimentation rate and production/decay of P in rivers and lakes. The model reproduced the temporal and spatial variations of discharge and TN/TP relatively well in both calibration (2006–2008) and validation (2009–2010) periods. The lowest NSEs (Nash-Suttclife Efficiency) of discharge, daily TN load, and daily TP load were 0.74, 0.51, and 0.54, respectively. The seasonal variations of daily TN concentrations in the entire simulation period were insufficient, indicated that crop rotation changed the timing and amount of N output. Monthly TN and TP simulation yields revealed that nutrient outputs were abundant in summer in terms of the corresponding discharge. The area-weighted TN and TP load annual yields in five years showed that nutrient loads were extremely high along Hong and Ru rivers, especially in agricultural lands
A Computational Perspective on Network Coding
From the perspectives of graph theory and combinatorics theory we
obtain some new upper bounds on the number of encoding nodes, which can characterize
the coding complexity of the network coding, both in feasible acyclic and cyclic multicast
networks. In contrast to previous work, during our analysis we first investigate the simple
multicast network with source rate h=2, and then h≥2. We find that for feasible acyclic
multicast networks our upper bound is exactly the lower bound given by M. Langberg et al. in 2006. So the gap between their lower and upper bounds for feasible acyclic multicast
networks does not exist. Based on the new upper bound, we improve the computational
complexity given by M. Langberg et al. in 2009. Moreover, these results further support
the feasibility of signatures for network coding
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