Summary
Time‐varying network link loss rate is a useful information for network managers to discover and locate the network link failures. This paper proposes a method to track time‐varying network ...link loss rates from unicast end‐to‐end measurements. The method first trains a state transition matrix to capture the spatio‐temporal characters of packet link transmission probabilities by sending end‐to‐end probe packets and then estimates the time‐varying link loss rates using the state transition matrix and the end‐to‐end measurements obtained from background traffic (the existed packets in network). We also introduce a validation step to check and retrain the state transition matrix in order to ensure the accuracy of the state transition matrix. Our method is capable of tracking the variation of link loss rates without incessantly sending probe packets, which is very feasible for many practical applications. The ns‐2 simulation results show the good performance of our method.
Time‐varying network link loss rate is useful information for network manager to discover and locate the network link failures. We present a time‐varying link loss rate tracking method to exploit spatio‐temporal relationships of link loss rates by sending probe packets, and estimate time‐varying link loss rates using the spatio‐temporal relationship under the constraint of background path‐level loss rates. The method tracks time‐varying link loss rates without incessantly sending probe packets, which is very feasible for many practical applications.
So far, many regression works have been implemented by using linear regression methods. Although more accurate predictions results could be obtained, polynomial regression is not used as much as ...compared to linear regression in real applications due to occurrence of coefficient explosion. To overcome this problem, two regression algorithms using Chebyshev polynomials of class 2 based on cascade regression and feature selection are proposed in this paper. In the experimental part, three separate experiments including function interpolation and real-case regression were conducted on three datasets to test the proposed algorithms. As shown by the experimental results, the proposed algorithms performed better than other regression methods in terms of both accuracy and processing time.
Nitrogen (N) and phosphorus (P) resorption from senescing organs are important plant nutrient conservation mechanisms. However, whether nutrient resorption can indicate plant adaptation to ...nutrient-poor environment remains a controversy. We quantified nutrient resorption efficiency of major species in an alpine meadow of the Qinghai-Tibetan Plateau. N and P resorption for these species averaged 65.2% and 67.4%, respectively, which was at the high end of the values of global scale. Among three life forms, sedges contained least N and P and had highest resorption efficiency, indicating sedges had a competitive advantage over grasses and forbs in this nutrient-poor environment. This result was consistent with the fact that sedge was the typically dominant plant functional group in Qinghai-Tibetan Plateau. By fitting the allometric equations (nutrientsenescent=A(nutrientlive)B) separately for N and P, we found much smaller B (N) than B (P), which suggested that relative to the resorption from senescent leaves, the cost of N uptake from soils increased more quickly than that of P as resource availability decreased. This phenomenon was contrary to the corresponding N and P acquisition pattern of the tropical ecosystem, which matched the large geographical gradients of N vs. P limitation (N for alpine ecosystem, while P for tropical ecosystem). This study suggests that surveying leaf nutrient concentration and resorption could provide indicative information about plant adaptation to nutrient-poor soil within and across ecosystems. Our finding offers insights to nutrient management and ecosystem restoration in nutrient-poor environment and delivers information for upcoming meta-studies and model simulation of global leaf nutrient resorption.
3D hosts have been widely investigated to stabilize the lithium (Li) metal anode (LMA) for next‐generation high‐energy‐density batteries. However, the complicated porous structure and the ...lithiophobic framework always lead to nonuniform Li deposition and low host utilization. Herein, Au nanoparticle (NP)–modified vertical graphenes, which are grown on flexible graphite paper, are prepared as the 3D host (denoted Au‐VG‐GP) to guide Li nucleation and deposition. It is shown that the vertical graphene structure with the low tortuosity effectively decreases the ion diffusion resistance and avoids the formation of a concentration gradient, ensuring uniform ion distribution in the 3D host. At the same time, the uniformly distributed Au NPs act as heterogeneous seeds guiding fast and uniform Li nucleation and growth. As a result, the Au‐VG‐GP host effectively stabilizes the LMA and achieves a high Coulombic efficiency in the half‐cells. A small overpotential and long cycling stability are also achieved for the LMA in the symmetrical cells and full batteries with such a host. In addition, such a host can also guide uniform and high‐capacity deposition of Li2S in the cathode of lithium–sulfur batteries, showing its potential uses in energy storage devices based on a dissolution–deposition mechanism.
Au nanoparticle–modified vertical graphenes are prepared by PECVD and sputtering method, serving as the 3D host to guide the nucleation and deposition of Li and Li2S. The vertical structure ensures uniform ion distribution and the Au heterogeneous seeds guide uniform nucleation and growth, showing its potential uses in energy storage devices based on a dissolution–deposition mechanism.
The discrepancies between geophysical measurements and forward-modelled data are commonly modelled as Gaussian errors, thereby necessitating the use of least-squares optimisation methods. However, ...given the many inevitable difficulties and ambiguities in data acquisition, processing, and interpretation, subsurface-property estimation from remote geophysical measurements is subject to non-Gaussian errors. We propose to minimise the misfit with a robust error measure, which is based on a generalised Gaussian distribution. A suboptimal solution is proposed through a mixed-norm functional combination of the l
1
norm and l
2
norm. A mixed-norm parameter is introduced to determine the relative importance between the l
1
norm and l
2
norm functional, which is a function of the kurtosis of the errors. The novelty of the proposed mixed-norm algorithm is that no knowledge of the seismic errors is required. The relative contributions of the l
1
norm and l
2
norm are adjusted based on the partially inverted elastic properties. Both synthetic and field data demonstrate the effectiveness of the proposed algorithm.
Subsurface-property estimation from remote geophysical measurements is subject to non-Gaussian errors. We propose to minimise the misfit with a robust error measure, which is based on a generalised Gaussian distribution. A suboptimal solution is proposed through a mixed-norm functional combination of the l
1
and l
2
norms.
Seismic inverse problems aim to infer the properties of subsurface geology, such as elastic and petrophysical properties. Existing seismic inversion methods for the joint estimation of these ...properties are mainly based either on Gassmann theory for prestack seismic data processed with stochastic optimisation techniques or on the Wyllie formula for poststack seismic data processed by deterministic optimisation techniques. The purpose of this study is to develop a strategy for the joint estimation of elastic and petrophysical properties from prestack seismic data based on Gassmann equations with deterministic optimisation techniques. Given poor-quality prestack seismic data, two regularisation parameters are introduced to control the trade-off between fidelity to the data and the smoothness of the solution. An appropriate linearised system of equations for the joint model update is derived from Newton's method, which fits seismic data, the description of the rock physics medium and prior information, simultaneously. We show the preliminary results obtained with the proposed framework for synthetic and real data examples.
In this letter, we propose a novel network topology measurement method called the neural network gradient-guided method (NGM), which can use traceroutes to efficiently collect topological information ...(IPs and links) by selecting appropriate destination IPs. In this method, the mapping between probing destination IPs and probing revenues is modelled into a multiclassification problem using a neural network model, and networks are iteratively probed under the guidance of the neural network gradients. Experimental results in real networks demonstrated that NGM can collect more IPs and links by comparing with the methods that randomly selects IPs and subnets for probing.
This study was performed to compare aortic remodeling and clinical outcomes in patients with acute, subacute, and chronic type B aortic dissection (TBAD) after thoracic endovascular aortic repair ...(TEVAR).
We retrospectively examined 323 consecutive patients with acute (
= 129), subacute (
= 161), and chronic (
= 33) TBAD who underwent TEVAR from June 2013 to December 2016 in in multicenter institution. Patient demographics, clinical data, and imaging characteristics were recorded and compared among the three groups.
The three groups had comparable baseline characteristics. Perioperative mortality rates were similar among the acute (2.3%), subacute (0.0%), and chronic (0.0%) groups (
= 0.34). Perioperative morbidity rates, including the rates of visceral and lower limb malperfusion and cerebral infraction, were also similar. The rate of perioperative endoleak was significantly higher in the chronic group (18.1%) than in the acute (3.9%) and subacute (3.7%) groups (
= 0.02). The mean follow-up duration was 78 ± 22 months (range, 36-101 months). The mortality rates were comparable among the three groups. The rates of reintervention and lower limb malperfusion were higher in the chronic group than in the acute and subacute groups. FL diameter reduction were more robust in the acute and subacute groups than in the chronic group.
Patients with acute, subacute, and chronic TBAD had different outcomes in this study. Patients with acute and subacute TBAD had fewer complications than those with chronic TBAD. Aortic remodeling after TEVAR was more favorable in patients with acute and subacute TBAD than in patients with chronic TBAD. TEVAR promotes more positive remodeling at the stent graft level than at the distal level of the aorta.
An unprecedented photocatalyst, Sm
EuSbO
, was successfully fabricated in this paper, through a high-temperature solid-state calcination method, which represented its first ever synthesis. ...Additionally, using the solvothermal method, the Sm
EuSbO
/ZnBiSbO
heterojunction photocatalyst (SZHP) was fabricated, marking its debut in this study. XRD analysis confirmed that both Sm
EuSbO
and ZnBiSbO
exhibited pyrochlore-type crystal structures with a cubic lattice, belonging to the Fd3m space group. The crystal cell parameter was determined to be 10.5682 Å or 10.2943 Å for Sm
EuSbO
or ZnBiSbO
, respectively. The band gap width measured for Sm
EuSbO
or ZnBiSbO
was 2.73 eV or 2.61 eV, respectively. Under visible light irradiation for 150 min (VLTI-150 min), SZHP exhibited remarkable photocatalytic activity, achieving 100% removal of parathion methyl (PM) concentration and 99.45% removal of total organic carbon (TOC) concentration. The kinetic constant (
) for PM degradation and visible light illumination treatment was determined to be 0.0206 min
, with a similar constant
of 0.0202 min
observed for TOC degradation. Remarkably, SZHP exhibited superior PM removal rates compared with Sm
EuSbO
, ZnBiSbO
, or N-doped TiO
photocatalyst, accompanied by removal rates 1.09 times, 1.20 times, or 2.38 times higher, respectively. Furthermore, the study investigated the oxidizing capability of free radicals through the use of trapping agents. The results showed that hydroxyl radicals had the strongest oxidative capability, followed by superoxide anions and holes. These findings provide a solid scientific foundation for future research and development of efficient heterojunction compound catalysts.
Increasing agricultural productivity and assessing the responses of soil properties in soils with different groups under intercropping are the key steps to meeting both forage demand and soil full ...utilization. The effect of intercropping oat (
Avena sativa
L.) and common vetch (
Vicia sativa
L.) on yield, soil nutrient availability in different soil textures was examined under five planting systems: sole common vetch (V), sole oat (O), or intercropped with common vetch at ratios 1:1, 2:1, and 3:1. The biomass in oat/common vetch intercropping 2:1 (OV2:1) and 3:1 was higher than that of other treatments except for monoculture oat. The soil available nitrogen (AN) of oat/common vetch intercropping 3:1 (OV3:1) was significantly (
P
< 0.05) higher than O except for chernozem. However, the soil available phosphorus (AP) in OV2:1 was significantly increased by 34.89% and 17.93%, 29.18% and 43.74%, and 39.31% and 14.22% compared with the corresponding oat monoculture while available potassium in saline-alkali was 17.57% and 11.75%, and 13.36% and 7.93% significantly higher than corresponding oat and common vetch monoculture. These results suggest that oat intercropped with common vetch at 3:1 could acquire high biomass while 2:1 is beneficial to the improvement of soil quality.
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