A new multi-phase-field method is developed for modeling the fracture of polycrystals at the microstructural level. Inter and transgranular cracking, as well as anisotropic effects of both elasticity ...and preferential cleavage directions within each randomly oriented crystal are taken into account. For this purpose, the proposed phase field formulation includes: (a) a smeared description of grain boundaries as cohesive zones avoiding defining an additional phase for grains; (b) an anisotropic phase field model; (c) a multi-phase field formulation where each preferential cleavage direction is associated with a damage (phase field) variable. The obtained framework allows modeling interactions and competition between grains and grain boundary cracks, as well as their effects on the effective response of the material. The proposed model is illustrated through several numerical examples involving a full description of complex crack initiation and propagation within 2D and 3D models of polycrystals.
A method for cobalt‐catalyzed, carboxylate‐directed functionalization of arene C−H bonds is reported. Alkynes, styrenes, and 1,3‐dienes can be coupled with benzoic acids to provide cyclic products in ...good yields. The reactions proceed in the presence of a cobalt(II) hexafluoroacetylacetonate catalyst, (TMS)2NH base, Ce(SO4)2 cooxidant, and oxygen oxidant.
A step in the right direction: A cobalt‐catalyzed, carboxylate‐directed functionalization of arene C−H bonds is reported. Alkynes, styrenes, and 1,3‐dienes are coupled with benzoic acids to provide cyclic products in good yields. The reactions proceed in the presence of a cobalt(II) hexafluoroacetylacetonate catalyst, (TMS)2NH base, O2 oxidant, and Ce(SO4)2 cooxidant.
A detailed understanding of households' shock-coping capacity is needed to design appropriate social safety net programs and interventions. We use a 2-year panel dataset from rural Cambodia to seek ...answers to the following research questions: (i) are rural households forced to reduce their consumption due to shocks? and (ii) what are the factors affecting households' choice of shock-coping strategies in response to shocks? The results of econometric models reveal that most covariate shocks have significant and negative effects on household consumption. In particular, total consumption expenditure and food consumption expenditure are negatively affected by floods, whereas household education expenditure is negatively affected by livestock diseases. These shocks also force households to use coping strategies of selling durable assets and extracting natural resources. Although droughts appear not to significantly affect household consumption, these shocks push households into using child labor, selling durable assets or extracting natural resources. Household consumption is shown to be not significantly affected by health shocks. Borrowing and receiving assistance from friends and relatives are identified as major coping strategies in response to health shocks. Our findings call for assistance programs to support households in preventing and mitigating the effects of floods, droughts and livestock diseases.
•Impacts of multiple shocks on household consumption and their coping strategies are investigated.•Food consumption is negatively affected by floods, education expenditure is negatively affected by livestock diseases.•Covariate shocks force households to adopt harmful strategies such as selling asset or extracting natural resources.•Households are insured against health shock by using risk-sharing strategies such as borrowing and receiving assistance.
Kubernetes, an open-source container orchestration platform, enables high availability and scalability through diverse autoscaling mechanisms such as Horizontal Pod Autoscaler (HPA), Vertical Pod ...Autoscaler and Cluster Autoscaler. Amongst them, HPA helps provide seamless service by dynamically scaling up and down the number of resource units, called pods, without having to restart the whole system. Kubernetes monitors default Resource Metrics including CPU and memory usage of host machines and their pods. On the other hand, Custom Metrics, provided by external software such as Prometheus, are customizable to monitor a wide collection of metrics. In this paper, we investigate HPA through diverse experiments to provide critical knowledge on its operational behaviors. We also discuss the essential difference between Kubernetes Resource Metrics (KRM) and Prometheus Custom Metrics (PCM) and how they affect HPA’s performance. Lastly, we provide deeper insights and lessons on how to optimize the performance of HPA for researchers, developers, and system administrators working with Kubernetes in the future.
This study uses the data of 1912 and 1815 rural households surveyed in 2016 and 2017, respectively in three provinces of Thailand to examine the factors affecting the decision of rural households to ...use the internet and the impacts of internet use on household income and poverty. Results from a probit model show that the decision of rural households to use the internet is positively associated with the education level of the household head, household size, labour share, farmland, and household productive assets, and the number of enterprises with at least nine employees in the village. But it is negatively associated with age of household head and share of male members in household. Results from a heteroscedasticity-based instrumental variable regression show that internet use for productive purposes increases household income, promotes development of non-farm sectors, and reduces the extraction of and reliance on natural resources. However, results from an unconditional quantile regression show that better-off households benefit relatively more from internet use than worse-off households. These findings indicate a positive income effect of internet use for productive purposes but also raise a concern of increasing income inequality among rural populations from internet development.
This paper investigates energy transition, energy poverty and energy inequality in Vietnam employing a longitudinal dataset of a nationally representative household survey. We use the data on ...residential energy expenditure of more than 9,000 households over the period 2004–2016. We find a transition from traditional energy to modern energy but this transition varies across regions, between ethnic and welfare groups and between rural and urban population. The poor and ethnic minority households still rely heavily on traditional energy sources such as coal and biomass to meet their energy demands. Electricity poverty has decreased but energy-cost poverty has increased. In addition, energy inequality tends to decrease at a more significant rate than income and consumption inequalities. We propose a national program for energy poverty alleviation be established to devise policies to lower households’ energy costs. Further assistance to the poor and ethnic minority households is also recommended so that they can afford a higher level of electricity consumption.
The use of the internet is growing rapidly and has become an engine for economic development. However, few studies have examined the impact of internet use on agricultural production, and the results ...are not yet conclusive. Employing a dataset of more than 2000 observations in rural Vietnam, our study analyses the impact of internet use on agricultural productivity using the heteroscedasticity‐based instrument approach suggested by Lewbel, Journal of Business and Economic Statistics, 2012, 30, 67–80 and examines the heterogeneity and distribution of the impact using quantile regressions. Our results show that internet use has significant and positive effects on agricultural productivity. However, these effects are heterogeneous across population groups. The positive effects of internet use are stronger for households with a lower level of education, with a young and female head, and from ethnic minorities. The benefits are also found to be skewed towards the group of farmers at the bottom of the productivity distribution. Therefore, we propose facilitating the diffusion of the internet, since it not only boosts agricultural productivity, but also reduces productivity inequality. In addition, we recommend promoting rural education, supporting local markets, investing more in irrigation systems, and facilitating farm mechanisation as these factors are found to contribute to increasing agricultural productivity.
In this paper, we present a new multi-physics computational framework that enables us to capture and investigate complex fracture behavior in cement-based materials at early-age. The present model ...consists of coupling the most important chemo-thermo-mechanical processes to describe temperature evolution, variation of hydration degree, and mechanical behavior. The changes of material properties are expressed as a function of the hydration degree, to capture the age effects. Fracture analysis of these processes is then accommodated by a versatile phase field model in the framework of smeared crack models, addressing the influence of cracks on hydration and thermal transfer. We additionally describe a stable and robust numerical algorithm, which aims to solve coupled problems by using a staggered scheme. The developed approach is applied to study the fracture phenomena for both homogeneous and heterogeneous concrete structures. Especially, in the second case, all microstructural heterogeneities of sand and cement matrix are explicitly accounted. Nucleation, initiation, and propagation of complex crack network are simulated in an efficient way demonstrating the potential of the proposed approach to assess the early-age defects in concrete structures and materials.
We consider network-assisted full-duplex (NAFD) cell-free massive multiple-input multiple-output (CF-mMIMO) systems, where full-duplex (FD) transmission is virtually realized via half-duplex (HD) ...hardware devices. The HD access points (APs) operating in uplink (UL) mode and those operating in downlink (DL) mode simultaneously serve DL and UL user equipments (UEs) in the same frequency bands. We comprehensively analyze the performance of NAFD CF-mMIMO from both a spectral efficiency (SE) and energy efficiency (EE) perspectives. Specifically, we propose a joint optimization approach that designs the AP mode assignment, power control, and large-scale fading (LSFD) weights to improve the sum SE and EE of NAFD CF-mMIMO systems. We formulate two mixed-integer nonconvex optimization problems of maximizing the sum SE and EE, under realistic power consumption models, and the constraints on minimum individual SE requirements, maximum transmit power at each DL AP and UL UE. The challenging formulated problems are transformed into tractable forms and two novel algorithms are proposed to solve them using successive convex approximation techniques. More importantly, our approach can be applied to jointly optimize power control and LSFD weights for maximizing the sum SE and EE of HD and FD CF-mMIMO systems, which, to date, has not been studied. Numerical results show that: (a) our joint optimization approach significantly outperforms the heuristic approaches in terms of both sum SE and EE; (b) in CF-mMIMO systems, the NAFD scheme can provide approximately 30% SE gains, while achieving a remarkable EE gain of up to 200% compared with the HD and FD schemes.
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