On minimizing coding operations in network coding based multicast: an evolutionary algorithm

In telecommunications networks, to enable a valid data transmission based on network coding, any intermediate node within a given network is allowed, if necessary, to perform coding operations. The more coding operations needed, the more coding resources consumed and thus the more computational overhead and transmission delay incurred. This paper investigates an efficient evolutionary algorithm to minimize the amount of coding operations required in network coding based multicast. Based on genetic algorithms, we adapt two extensions in the proposed evolutionary algorithm, namely a new crossover operator and a neighbourhood search operator, to effectively solve the highly complex problem being concerned. The new crossover is based on logic OR operations to each pair of selected parent individuals, and the resulting offspring are more likely to become feasible. The aim of this operator is to intensify the search in regions with plenty of feasible individuals. The neighbourhood search consists of two moves which are based on greedy link removal and path reconstruction, respectively. Due to the specific problem feature, it is possible that each feasible individual corresponds to a number of, rather than a single, valid network coding based routing subgraphs. The neighbourhood search is applied to each feasible individual to find a better routing subgraph that consumes less coding resource. This operator not only improves solution quality but also accelerates the convergence. Experiments have been carried out on a number of fixed and randomly generated benchmark networks. The results demonstrate that with the two extensions, our evolutionary algorithm is effective and outperforms a number of state-of-the-art algorithms in terms of the ability of finding optimal solutions

Acoustic echo suppression using a learning-based multi-frame minimum variance distortionless response filter

Distortion resulting from acoustic echo suppression (AES) is a common issue in full-duplex communication. To address the distortion problem, a multi-frame minimum variance distortionless response (MFMVDR) filtering technique is proposed. The MFMVDR filter with parameter estimation which was used in speech enhancement problems is extended in this study from a deep learning perspective. To alleviate numerical instability of the MFMVDR filter, we propose to directly estimate the inverse of the correlation matrix. The AES system is advantageous in that no double-talk detection is required. The negative scale-invariant signal-to-distortion ratio is employed as the loss function in training the network at the output of the MFMVDR filter. Simulation results have demonstrated the efficacy of the proposed learning-based AES system in double-talk, background noise, and nonlinear distortion conditions.Comment: Submitted to International Workshop on Acoustic Signal Enhancement (IWAENC) 202

Title: On Minimizing Coding Operations in Network Coding Based Multicast: An Evolutionary Algorithm

In telecommunications networks, to enable a valid data transmission based on network coding, any intermediate node within a given network is allowed, if necessary, to perform coding operations. The more coding operations needed, the more coding resources consumed and thus the more computational overhead and transmission delay incurred. This paper investigates an efficient evolutionary algorithm to minimize the amount of coding operations required in network coding based multicast. Based on genetic algorithms, we adapt two extensions in the proposed evolutionary algorithm, namely a new crossover operator and a neighbourhood search operator, to effectively solve the highly complex problem being concerned. The new crossover is based on logic OR operations to each pair of selected parent individuals and the resulting offspring are more likely to become feasible. The aim of this operator is to intensify the search in regions with plenty of feasible individuals. The neighbourhood search consists of two moves which are based on greedy link removal and path reconstruction, respectively. Due to the specific problem feature, it is possible that each feasible individual corresponds to a number of, rather than a single, valid network coding based routing subgraphs. The neighbourhood search is applied to each feasible individual to find a fitter routing subgraph that consumes less codin

Notch1 activation in embryonic VE-cadherin populations selectively blocks hematopoietic stem cell generation and fetal liver hematopoiesis.

Hematopoietic stem cells (HSC) are found in several independent sites embryonically. Loss-of-function studies indicated that Notch1, but not Notch2 signaling was required for HSC emergence from the aortic-gonado-mesonephros (AGM) region. We previously showed that constitutive Notch1 activation impaired primitive erythroid differentiation, but its effects on HSC emergence from the AGM region were not studied. To further define specific roles of Notch receptors, we characterized HSC in mouse embryos expressing either Notch1 intracellular domain (ICD) or Notch4ICD in VE-cadherin or SM22α expressing populations. Although embryonic Notch1 activation in VE-cadherin populations led to lethality after E13.5, earlier defects in the fetal liver were observed. Embryos were analyzed at E12.5 to assess hematopoiesis and the phenotype of developing cells in the AGM region. We found that activation of Notch1 in the endothelial compartment in VE-cadherin expressing cells resulted in the absence of intra-aortic clusters and defects in fetal liver hematopoiesis. In contrast, although Notch4 expression is regulated during fetal hematopoiesis, activation of Notch4 in VE-cadherin expressing populations did not affect HSC phenotype, although later vascular remodeling was impaired. Likewise, activation of Notch1 in SM22α positive populations had no significant effect on hematopoiesis. Our results indicate a cell type-dependent activity and distinct features of Notch1 versus Notch4 signaling and their impact on HSC generation

Concentration distributions and reaction pathways of species in the mass transfer process from atmospheric pressure plasma jet to water

Plasma–liquid interactions are becoming an increasingly significant topic in the field of low-temperature plasma science and technology. This work builds up a drift-diffusion model to numerically investigate concentration distributions and reaction pathways of various species in the mass transfer process from atmospheric pressure plasma jet (APPJ) to water. The simulation results indicate that H2O2 is a persistent molecular compound in the liquid phase region. Except for H2O2, the species concentrations of O3 and OH are relatively higher in the shallow region of water. The species O3, OH, and HO2 have approximately the same penetration depth in the liquid region. H2O2 is primarily generated by O(1D) + H2O → H2O2 due to the continuous mass transfer of O(1D) from APPJ to water. Furthermore, 2OH → H2O2 also produces a great deal of H2O2 in the liquid phase region

Validating Surfactant Performance in the Eagle Ford Shale: A Correlation Between the Reservoir-on-a-Chip Approach and Enhanced Well Productivity

For liquids-rich shale plays, surfactants have proven to be a critical component in hydraulic fracturing fluid systems for enabling enhanced oil and gas recovery. The industry\u27s most commonly used surfactant is a non-emulsifying surfactant (NES), but it has been previously demonstrated that a weakly emulsifying surfactant (WES) appears to be more efficient at mobilizing oil through tight pore throats. In this study, fundamental differences between those two surfactant types were further demonstrated using a Reservoir-on-a-Chip (ROC) approach, which allows direct visualization of oil recovery with the various surfactant fluids, allowing for the testing on both homogenous and heterogeneous pore structures with various geometries. The laboratory testing showed that, compared to a non-surfactant-bearing control fluid and the NES, the WES showed higher oil recovery efficiency at equal driving pressure. As a result of the laboratory testing indications, a multiple well trial program was conducted in two separate areas of the Eagle Ford shale. Production data from the wells stimulated using a WES-bearing fracturing fluid were normalized in terms of lateral lengths and fracturing stages, and compared to the offset wells stimulated using a NES-bearing fracturing fluid. Early production results suggest that wells treated with the WES exhibited enhanced productivity compared to those treated with the NES

Metabolomics Reveals Distinct Carbon and Nitrogen Metabolic Responses to Magnesium Deficiency in Leaves and Roots of Soybean [Glycine max (Linn.) Merr.]

Magnesium (Mg) deficiency, a widespread yet overlooked problem in agriculture, has been reported to retard plant growth and development, through affecting key metabolic pathways. However, the metabolic responses of plant to Mg deficiency is still not fully understood. Here we report a metabolomic study to evaluate the metabolic responses to Mg deficiency in soybean leaves and roots. Hydroponic grown soybean were exposed to Mg starvation for 4 and 8 days, respectively. Metabolic changes in the first mature trifoliolate leaves and roots were quantified by conducting GC-TOF-MS based metabolomic analysis. Principal component analysis (PCA) showed that Mg deficient plants became distinguishable from controls at 4 days after stress (DAS) at metabolic level, and were clearly discriminated at 8 DAS. Mg deficiency could cause large metabolite alterations on carbon and nitrogen metabolism. At 8 DAS, carbon allocation from shoot to root is decreased by Mg deficiency. Remarkably, most amino acids (such as phenylalanine, asparagine, leucine, isoleucine, glycine, glutamine, and serine) showed pronounced accumulation in the leaves, while most organic acids (including pyruvic acid, citric acid, 2-keto-glutaric acid, succinic acid, fumaric acid, and malic acid) were significantly decreased in the roots. Our study shows that the carbon and nitrogen metabolic responses are distinct in leaves and roots under Mg deficiency