Methane (CH4) is the major component of currently abundant natural gas and a prominent green-house gas. Steam reforming of methane (SRM) is an important technology for the conversion of CH4 into H2 ...and syngas. To improve the catalytic activity and coking resistance of SRM catalysts, great efforts (including the addition of promoters, development of advanced supports, and structural modification, etc.) have been made with considerable progress in the past decade. Meanwhile, a series of novel processes have been explored for more efficient and energy-saving SRM. In this scenario, a comprehensive review on the recent advances in SRM is necessary to provide a constructive insight into the development of SRM technology, however, is still lacking. Herein, the improvements in catalyst construction for conventional SRM and the newly developed SRM processes in the past decade are presented and analyzed. First, the critical issues of SRM catalysts are briefly introduced. Then, the recent research advances of the most popular Ni based catalysts and the catalysts based on the other non-noble metals (Co, Cu, Mo etc.) and the efficient but costly noble metals (Au, Pt, Pd, Rh, Ru etc.) are discussed. Furthermore, the development of the representative modified SRM processes, including thermo-photo hybrid SRM, sorbent enhanced SRM, oxidative SRM, chemical looping SRM, plasma and electrical-field enhanced SRM, is demonstrated, and their advantages and limits are compared. Finally, a critical perspective is provided to enlighten future work on this significant area.
•Steam reforming of methane (SRM) makes valuable use of abundant natural gas efficiently.•SRM is attractive for global warming mitigation and green energy (H2) production.•Recent efforts in catalyst design for efficient and stable SRM are addressed.•Advanced SRM technologies with hybrid processes have shown great promise.•Future efforts in novel SRM system for value added products is intriguing.
Biomass-derived photothermal conversion materials are considered to be promising evaporator choices for cost-effective, sustainable, and environmentally friendly solar vapor generation. Herein we ...demonstrate a double-layer flamed straw, which is a typical solar-driven interfacial evaporator that can directly convert solar energy into heat and then localize heat at interface for vapor generation. Benefiting from the unique structure of a natural corn straw, the flamed straw exhibits a high solar absorbance of 91%, ultralow thermal conductivity (0.042 W m–1 K–1), and a sufficient water supply. Notably, the flamed-straw evaporator achieves a fast evaporation rate of 1.497 kg m–2 h–1 and a high photothermal efficiency of 86% under 1 sun illumination, showing comparable efficiency with the reported studies. Our work highlights the promise of using the low-cost biomass-derived materials as highly effective solar vapor generators in the realm of seawater desalination and wastewater treatment.
In 2020, China promised to achieve carbon peaking by 2030 and carbon neutrality by 2060, and these targets are famous as “Goal 3060” in China. Chinese resource-based cities are concerned about the ...realization of Goal 3060 to practice national action against environmental change. In this paper, this study evaluates the impact of population, economic growth, energy intensity, industrial structure, fixed asset investment, and urbanization level on carbon emissions in Chinese cities. To do so, the paper divides 36 Chinese cities into four types (growing city, mature city, recessionary city, and regenerative city) from 2003 to 2017 by factor investigation according to the diverse development stages. The extended STIRPAT model is used to assess the impact of various factors on CO
2
emissions in the Yellow River basin and diverse city levels. The panel regression analysis was conducted for the basin as a whole and cities at different development stages through a fixed-effects model and a linear regression model with Driscoll-Kraay standard errors. The results show that (1) the total carbon emissions in the Yellow River basin continued to climb during the study period. However, the growth rate slowed down significantly after 2012. In addition, there are differences in the total carbon emissions and growth rate of different cities. (2) Population, real GDP, energy intensity, industrial structure, and fixed asset investment all have a significant positive impact on carbon emissions in the overall basin except the urbanization level which has a significant negative influence on carbon emissions. (3) There is heterogeneity in the influencing factors of carbon emissions in resource-based cities at various development stages. Based on these results, corresponding policies are proposed for different types of cities to help resource-based cities achieve the 3060 dual carbon goal.
Resilient Asymptotic Consensus in Robust Networks LeBlanc, H. J.; Haotian Zhang; Koutsoukos, X. ...
IEEE journal on selected areas in communications,
04/2013, Letnik:
31, Številka:
4
Journal Article
Recenzirano
Odprti dostop
This paper addresses the problem of resilient in-network consensus in the presence of misbehaving nodes. Secure and fault-tolerant consensus algorithms typically assume knowledge of nonlocal ...information; however, this assumption is not suitable for large-scale dynamic networks. To remedy this, we focus on local strategies that provide resilience to faults and compromised nodes. We design a consensus protocol based on local information that is resilient to worst-case security breaches, assuming the compromised nodes have full knowledge of the network and the intentions of the other nodes. We provide necessary and sufficient conditions for the normal nodes to reach asymptotic consensus despite the influence of the misbehaving nodes under different threat assumptions. We show that traditional metrics such as connectivity are not adequate to characterize the behavior of such algorithms, and develop a novel graph-theoretic property referred to as network robustness. Network robustness formalizes the notion of redundancy of direct information exchange between subsets of nodes in the network, and is a fundamental property for analyzing the behavior of certain distributed algorithms that use only local information.
A Notion of Robustness in Complex Networks Haotian Zhang; Fata, Elaheh; Sundaram, Shreyas
IEEE transactions on control of network systems,
2015-Sept., 2015-9-00, Letnik:
2, Številka:
3
Journal Article
Recenzirano
We consider a graph-theoretic property known as r-robustness which plays a key role in a class of consensus (or opinion) dynamics where each node ignores its most extreme neighbors when updating its ...state. Previous work has shown that if the graph is r-robust for sufficiently large r, then such dynamics will lead to consensus even when some nodes behave in an adversarial manner. The property of r-robustness also guarantees that the network will remain connected even if a certain number of nodes are removed from the neighborhood of every node in the network and thus it is a stronger indicator of structural robustness than the traditional metric of graph connectivity. In this paper, we study this notion of robustness in common random graph models for complex networks; we show that the properties of robustness and connectivity share the same threshold function in Erdös-Rényi graphs, and have the same values in 1-D geometric graphs and certain preferential attachment networks. This provides new insights into the structure of such networks, and shows that they will be conducive to the types of dynamics described before. Although the aforementioned random graphs are inherently robust, we also show that it is coNP-complete to determine whether any given graph is robust to a specified extent.
•The spatial-temporal characteristics of carbon emissions are different for each land use type.•Construction land is the main source of carbon.•Carbon emissions in the Yellow River Delta were ...spatially clustered.•The distribution of carbon emissions is larger in the “east-west” than in the “north-south”.
Land use is a major source of anthropogenic carbon emissions and a driver of climate change, so it is necessary to explore the spatial and temporal distribution characteristics of carbon emissions from different land use types. Based on the land use type data and fossil energy consumption data in the same period, we analyzed the spatial and temporal distribution characteristics of carbon emissions in the Yellow River Delta from 2000 to 2019 by constructing a carbon emission model, carbon footprint and Moran’s I index. The empirical results show that total net carbon emissions in the Yellow River Delta increased from 3.1×1010kg to 1.5×1011kg during 2000–2019. Construction land is the main source of carbon, while forest land and water contribute more to the total carbon sink in the study area. Carbon emissions in the Yellow River Delta were spatially clustered, characterized by a larger distribution of carbon emissions in the “east-west” direction than in the “north-south” direction. The results of the study are conducive to a comprehensive understanding of the spatial distribution pattern of land use carbon sources/sinks in the Yellow River Delta, and provide a certain reference basis for the formulation of low-carbon economic policies in the region.
Tumor cells are characterized as redox-heterogeneous intracellular microenvironment due to the simultaneous overproduction of reactive oxygen species and glutathione. Rational design of ...redox-responsive drug delivery systems is a promising prospect for efficient cancer therapy. Herein, six paclitaxel-citronellol conjugates are synthesized using either thioether bond, disulfide bond, selenoether bond, diselenide bond, carbon bond or carbon-carbon bond as linkages. These prodrugs can self-assemble into uniform nanoparticles with ultrahigh drug-loading capacity. Interestingly, sulfur/selenium/carbon bonds significantly affect the efficiency of prodrug nanoassemblies. The bond angles/dihedral angles impact the self-assembly, stability and pharmacokinetics. The redox-responsivity of sulfur/selenium/carbon bonds has remarkable influence on drug release and cytotoxicity. Moreover, selenoether/diselenide bond possess unique ability to produce reactive oxygen species, which further improve the cytotoxicity of these prodrugs. Our findings give deep insight into the impact of chemical linkages on prodrug nanoassemblies and provide strategies to the rational design of redox-responsive drug delivery systems for cancer therapy.
As a potential solution to improve wireless security, specific emitter identification is a lightweight access authentication technology. However, the existed deep learning‐based specific emitter ...identification methods are highly dependent on the training sample size, leading to serious overfitting problem when the training samples are inadequate, which obstructs their practical applications. To address this issue, an innovative data augmentation method to effectively expand the sample size is proposed. In this design, after data preprocessing, a random integration based data augmentation is applied to integrate several initial samples and generate new samples. Furthermore, compared with the existed methods, chaotic sequences are utilized to randomly set the integration weight of each initial sample, and thus enhancing the diversity of augmented samples. The superiority of the proposed chaotic integration‐based data augmentation method in accuracy, generalization ability and robustness is validated by the hardware implementation on digital mobile radio portable radios.
The existed deep learning‐based specific emitter identification methods are highly dependent on the training sample size, leading to serious overfitting problem when the training samples are inadequate. To address this issue, the chaotic sequences are combined with the random integration to improve the diversity and maximum quantity of the augmented samples. Therefore, the proposed chaotic integration‐based data augmentation method is able to significantly enhance the specific emitter identification performances of the deep learning classifiers with extremely small sample size, which is validated through the results of extensive experiments.
Breast cancer contributes to high mortality rates as a result of metastasis. Tumor-derived exosomes facilitate the development of the premetastatic environment, interacting and inhibiting the normal ...function of immune cells, thereby forming an immunosuppressive microenvironment for tumor metastasis. Herein, the platelet and neutrophil hybrid cell membrane (PNM) was embellished on a gold nanocage (AuNC) surface called nanosponges and nanokillers (NSKs). NSKs can simultaneously capture and clear the circulating tumor cells (CTCs) and tumor-derived exosomes via high-affinity membrane adhesion receptors, effectively cutting off the connection between exosomes and immune cells. Bionic NSK is loaded with doxorubicin (DOX) and indocyanine green (ICG) for synergic chemo-photothermal therapy. NSKs show greater cellular uptake, deeper tumor penetration, and higher cytotoxicity to tumor cells in comparison to non-coated AuNCs or single-coated AuNCs in vitro. In vivo, the multipurpose NSKs could not only completely ablate the primary tumor but also inhibit breast cancer metastasis with high efficiency in xenograft and orthotopic breast tumor-bearing models. Thus, NSKs could be a promising nanomedicine for the future clinical intervention of breast cancer metastasis.
Aerosols and Surface Albedo (SA) are critical in balancing Earth’s energy budget. With the changes of surface types and corresponding SA in recent years, an intriguing yet unresolved question ...emerges: how does Aerosol Direct Radiative Effect (ADRE) and its warming effect (AWE) change with varying SA? Here we investigate the critical SA marking ADRE shift from negative to positive under varying aerosol properties, along with the impact of SA on the ADRE. Results show that AWE often occurs in mid-high latitudes or regions with high-absorptivity aerosols, with critical SA ranging from 0.18 to 0.96. Thinner and/or more absorptive aerosols more readily cause AWE statistically. In regions where the SA trend is significant, SA has decreased at −0.012/decade, causing a −0.2 ± 0.17 W/m²/decade ADRE change, with the most pronounced changes in the Northern Hemisphere during June-July. As SA declines, we highlight enhanced ADRE cooling or reduced AWE, indicating aerosols’ stronger cooling, partly countering the energy rise from SA reduction.This study shows that decreased surface albedo leads to significant cooling from the aerosol direct radiative effect, especially in the Northern Hemisphere, moderating the expected warming from surface albedo reduction.
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