Power systems are exceedingly faced with extreme events such as natural disasters and deliberate attacks. In comparison, the underground natural gas system is considered less vulnerable to such ...extreme events. We consider that the overhead power grid can be hardened by replacing segments of electric power grid with underground natural gas pipelines as an energy transportation system to countereffect extreme events which can damage interdependent infrastructures severely. In this paper, an integrated electricity and natural gas transportation system planning algorithm is proposed for enhancing the power grid resilience in extreme conditions. A variable uncertainty set is developed to describe the interactions among power grid expansion states and extreme events. The proposed planning problem is formulated as a two-stage robust optimization problem. First, the influence of extreme events representing natural disasters is described by the proposed variable uncertainty set and the proposed robust model for the integrated planning is solved with the grid resilience represented by a set of constraints. Second, the investment decisions are evaluated iteratively using the conditional events. The integrated electricity and natural gas planning options are analyzed using the modified IEEE-RTS 1979 for enhancing the power grid resilience. The numerical results point out that the proposed integrated planning is an effective approach to improving the power grid resilience.
A coordinated operation of smart grid (SG) and intelligent transportation system (ITS) provides electric vehicle (EV) owners with a myriad of power and transportation network data for EV charging ...navigation. However, the optimal charging navigation would be a challenging task owing to the randomness of traffic conditions, charging prices and waiting time at EV charging station (EVCS). In this paper, we propose a deep reinforcement learning (DRL)-based EV charging navigation, aiming at minimizing the total travel time and the charging cost at EVCS. First, we utilize the deterministic shortest charging route model (DSCRM) to extract feature states out of collected stochastic data and then formulate EV charging navigation as a Markov Decision Process (MDP) with an unknown transition probability. The proposed DRL-based approach will approximate the solution, which can adaptively learn the optimal strategy without any prior knowledge of uncertainties. Case studies are carried out within a practical zone in Xi'an city, China. Numerous experimental results verity the effectiveness of the proposed approach and illustrate its adaptation to EV driver preferences. The coordination effect of SG and ITS on reducing the waiting time and the charging cost in EV charging navigations is also analyzed.
Electric power and transportation networks become increasingly coupled through electric vehicles (EV) charging station (EVCS) as the penetration of EVs continues to grow. In this paper, we propose a ...holistic framework to enhance the operation of coordinated electric power distribution network (PDN) and urban transportation network (UTN) via EV charging services. Under this framework, a bi-level model is formulated to optimally determine EVCS charging service fees (CSF) for guiding EV charging behaviors and minimizing the total social cost. At the upper level, PDN with wind power generation is formulated as a second-order cone problem (SOCP) where CSF is determined. Given the settings calculated at the upper level, the lower level problem is described as a traffic assignment problem (TAP) which is subject to the user equilibrium (UE) principle and captures the individual rationality of single EV owners in UTN. The uncertainties in wind power output and origin-destination (O-D) traffic demands are considered in the proposed model and a deep reinforcement learning (DRL)-based solution framework is developed to decouple and approximately solve the stochastic bi-level problem. Both gradient-based and gradient-free training algorithms are implemented in this paper and the respective results are compared. The case studies on a 5-node system, 24-node Sioux-Falls system and real-world Xi'an city in China are conducted to verify the effectiveness of the proposed model, which demonstrates the enhanced operation of coordinated PDN and UTN networks by reducing the traffic congestion and improving the integration of renewable energy.
Inorganic cesium lead halide perovskite solar cells (PSCs) have received enormous attention due to their excellent stability compared with that of their organic–inorganic counterparts. However, the ...lack of optimization strategies leads the inorganic PSCs to suffer from low efficiency arising from significant recombination. To overcome this dilemma, a surface modification of the electron transport layer (ETL)/perovskite interface is undertaken by using SmBr3 to improve the crystallization and morphology of the perovskite layer for enhanced ETL/perovskite interface interaction. Encouragingly, a gradient energy band is created at the interface with an outstanding hole blocking effect. As a result, both the charge recombination occurring at the interface and the nonradiative recombination inside the perovskite are suppressed, and, simultaneously, the charge extraction is improved successfully. Therefore, the power conversion efficiency of the CsPbIBr2 PSCs is increased to as high as 10.88% under one sun illumination, which is 30% higher than its counterparts without the modification. It is logically inferred that this valuable optimization strategy can be extended to other analogous structures and materials.
To optimize inorganic perovskite based solar cells, a lanthanide halide is employed to modify the electron transport layer/perovskite interface and form a gradient energy band, which can restrain the charge recombination at the interface and inside the perovskite. Eventually, an efficiency as high as 10.88% is obtained, representing the highest efficiency of CsPbIBr2 perovskite solar cells.
Scrupulous design and smart hybridization of bespoke electrode materials are of great importance for the advancement of sodium ion batteries (SIBs). Graphene‐based nanocomposites are regarded as one ...of the most promising electrode materials for SIBs due to the outstanding physicochemical properties of graphene and positive synergetic effects between graphene and the introduced active phase. In this review, the recent progress in graphene‐based electrode materials for SIBs with an emphasis on the electrode design principle, different preparation methods, and mechanism, characterization, synergistic effects, and their detailed electrochemical performance is summarized. General design rules for fabrication of advanced SIB materials are also proposed. Additionally, the merits and drawbacks of different fabrication methods for graphene‐based materials are briefly discussed and summarized. Furthermore, multiscale forms of graphene are evaluated to optimize electrochemical performance of SIBs, ranging from 0D graphene quantum dots, 2D vertical graphene and reduced graphene oxide sheets, to 3D graphene aerogel and graphene foam networks. To conclude, the challenges and future perspectives on the development of graphene‐based materials for SIBs are also presented.
The recent progress of multiscale graphene‐based electrode materials for application in sodium ion batteries in respect of electrode design principle, preparation methods, characterization, synergistic effects, and electrochemical performance is reviewed, and future challenges and prospects of the field are presented.
This book addresses unique issues and many challenges in the entire “food chain” of natural gas engineering related to upstream, midstream and downstream. It can serve as a reference book for all ...engineers in the energy business, a textbook for students in petroleum and chemical engineering curricula, and a handbook for training departments of a large group of companies.
Photothermal therapy (PTT) is attracting increasing interest and becoming more widely used for skin cancer therapy in the clinic, as a result of its noninvasiveness and low systemic adverse effects. ...However, there is an urgent need to develop biocompatible PTT agents, which enable accurate imaging, monitoring, and diagnosis. Herein, a biocompatible Gd-integrated CuS nanotheranostic agent (Gd:CuS@BSA) was synthesized via a facile and environmentally friendly biomimetic strategy, using bovine serum albumin (BSA) as a biotemplate at physiological temperature. The as-prepared Gd:CuS@BSA nanoparticles (NPs) with ultrasmall sizes (ca. 9 nm) exhibited high photothermal conversion efficiency and good photostability under near-infrared (NIR) laser irradiation. With doped Gd species and strong tunable NIR absorbance, Gd:CuS@BSA NPs demonstrate prominent tumor-contrasted imaging performance both on the photoacoustic and magnetic resonance imaging modalities. The subsequent Gd:CuS@BSA-mediated PTT result shows high therapy efficacy as a result of their potent NIR absorption and high photothermal conversion efficiency. The immune response triggered by Gd:CuS@BSA-mediated PTT is preliminarily explored. In addition, toxicity studies in vitro and in vivo verify that Gd:CuS@BSA NPs qualify as biocompatible agents. A biodistribution study demonstrated that the NPs can undergo hepatic clearance from the body. This study highlights the practicality and versatility of albumin-mediated biomimetic mineralization of a nanotheranostic agent and also suggests that bioinspired Gd:CuS@BSA NPs possess promising imaging guidance and effective tumor ablation properties, with high spatial resolution and deep tissue penetration.
The high performance of a pseudocapacitor electrode relies largely on a scrupulous design of nanoarchitectures and smart hybridization of bespoke active materials. We present a powerful two-step ...solution-based method for the fabrication of transition metal oxide core/shell nanostructure arrays on various conductive substrates. Demonstrated examples include Co(3)O(4) or ZnO nanowire core and NiO nanoflake shells with a hierarchical and porous morphology. The "oriented attachment" and "self-assembly" crystal growth mechanisms are proposed to explain the formation of the NiO nanoflake shell. Supercapacitor electrodes based on the Co(3)O(4)/NiO nanowire arrays on 3D macroporous nickel foam are thoroughly characterized. The electrodes exhibit a high specific capacitance of 853 F/g at 2 A/g after 6000 cycles and an excellent cycling stability, owing to the unique porous core/shell nanowire array architecture, and a rational combination of two electrochemically active materials. Our growth approach offers a new technique for the design and synthesis of transition metal oxide or hydroxide hierarchical nanoarrays that are promising for electrochemical energy storage, catalysis, and gas sensing applications.
The relatively fixed residential day-ahead real-time electricity price reflects insufficient information of the market, so the response of residential energy management system (EMS) to the real-time ...pricing (RTP) is not complete and therefore retailers are exposed to the risk of price fluctuation in balance market. Direct load control (DLC) in cooperative game is proposed in this paper. A cooperative game union comprised of some users and a retailer is established to minimize the union costs. The union provides an opportunity to access the balance market indirectly for residents and to reduce risks and costs for the retailer. In addition, Shapley value which embodies the fairness is used in union profits allocation. The method that avoids bidding for residential users simplifies the thresholds of residents to participate in market. Furthermore, the DLC union contributes to imbalance self-management for the retailer, which helps him avoid paying for the regulation cost involved in the deviation between the total quantity bought at markets and the actual consumption. The achievement of union's goal respects the constraints set by users. The method that alleviates the disturbance of DLC to residents meets the dual goals of being both fully responsive and non-disruptive.
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