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AbstractAs the unique rotating component, the impeller is the core component of a nuclear reactor coolant pump (RCP), the dynamic properties of the impeller are critical for the safe operation of the whole reactor. The purpose of this study was to shed comprehensive light on the pressure pulsation and modal properties of a scaled RCP impeller via experimental and numerical methods. The numerical model was validated by an experiment connecting the pressure pulsation signals at the diffuser inlet, and a good agreement was obtained between the numerical and experimental results. Pressure pulsation acting on the impeller's blade is mainly dominated by the impeller rotating frequency, the vane passing frequency, and the double blade‐passing frequency, and the pressure pulsation acting on the blade's pressure surface is more intense than on the suction surface. The modal properties were obtained via the modal test and numerical methods with the impeller suspended as a free body in the air and submerged inside water. The reduction in the impeller natural frequencies was between 31.63% and 37.77% for the corresponding mode shape due to the added mass effect of the fluid. Based on the pressure pulsation characteristics acting on the impeller and the natural frequency of the impeller, it is considered there is no risk of resonance in the impeller. Finally, it is expected that the present work can provide scientific guidance to avoid hydraulic resonance in nuclear reactor coolant pumps.

Los nodos de red de sensores inalámbricos tienen una energía limitada, la forma de emplear la energía limitada de manera eficiente para realizar una transmisión de datos efectiva se ha convertido en un tema candente. Teniendo en cuenta las características de la plantación de huertos en filas y sombras causadas por características aleatorias dispersas, para mejorar la eficiencia energética de la red de sensores inalámbricos de huertos y prolongar la vida útil de la red, proponemos un algoritmo mejorado de enrutamiento jerárquico de agrupamiento basado en cadenas (ICCHR) basado en el algoritmo de LIXIVIACIÓN. El algoritmo ICCHR investiga la formación de grupos, la elección de la cabeza del grupo, la formación de la cadena, así como el proceso de transmisión de datos, y además se simula con los algoritmos E-LEACH, PEGASIS-E, LEACH-1R PEGASIS y P-LEACH a través de MATLAB. Los resultados de la simulación muestran que para BS en (50, 175), desde el punto de vista de la métrica de muerte de todos los nodos sensores, la vida útil de la red para el algoritmo ICCHR se prolonga aproximadamente 3.29, 8.78, 35.53 y 43.11% en comparación con los algoritmos E-LEACH, PEGASIS-E, LEACH-1R PEGASIS y P-LEACH. El consumo medio de energía por ronda del algoritmo ICCHR es inferior a los algoritmos E-LEACH, PEGASIS-E, LEACH-1R PEGASIS y P-LEACH en aproximadamente 4,73, 9,04, 35,60 y 43,31%. Esta investigación puede proporcionar referencias teóricas para las redes inalámbricas del entorno complejo del huerto. Les nœuds de réseau de capteurs sans fil ont une énergie limitée, comment utiliser efficacement une énergie limitée pour réaliser une transmission de données efficace est devenu un sujet brûlant. Compte tenu des caractéristiques de la plantation de vergers en rangées et à l'ombre causées par des caractéristiques aléatoires clairsemées, afin d'améliorer l'efficacité énergétique du réseau de capteurs sans fil du verger et de prolonger la durée de vie du réseau, nous proposons un algorithme amélioré de routage hiérarchique en grappe basé sur la chaîne (ICCHR) basé sur l'algorithme de LIXIVIATION. L'algorithme ICCHR étudie la formation de grappes, l'élection de la tête de grappe, la formation de la chaîne ainsi que le processus de transmission de données, et est ensuite simulé avec les algorithmes E-LEACH, PEGASIS-E, LEACH-1R PEGASIS et P-LEACH via Matlab. Les résultats de simulation montrent que pour BS à (50, 175), du point de vue de toutes les métriques de mort des nœuds du capteur, la durée de vie du réseau pour l'algorithme ICCHR prolonge d'environ 3,29, 8,78, 35,53 et 43,11% par rapport aux algorithmes E-LEACH, PEGASIS-E, LEACH-1R PEGASIS et P-LEACH. La consommation d'énergie moyenne par tour de l'algorithme ICCHR est inférieure à celle des algorithmes E-LEACH, PEGASIS-E, LEACH-1R PEGASIS et P-LEACH d'environ 4,73, 9,04, 35,60 et 43,31 %. Cette recherche peut fournir des références théoriques pour le réseau sans fil de l'environnement complexe du verger. Wireless sensor network nodes have limited energy, how to employ limited energy efficiently to realize effective data transmission has become a hot topic. Considering the characteristics of orchard planting in rows and shade caused by sparse random features, to improve energy efficiency of the orchard wireless sensor network and prolong network lifetime, we propose an improved chain-based clustering hierarchical routing (ICCHR) algorithm based on LEACH algorithm. The ICCHR algorithm investigates the formation of clusters, cluster head election, chain formation as well as the data transmission process, and further simulated with E-LEACH, PEGASIS-E, LEACH-1R PEGASIS and P-LEACH algorithms through MATLAB. The simulation results show that for BS at (50, 175), from the point of view of all sensor nodes death metric, the network lifetime for ICCHR algorithm prolongs about 3.29, 8.78, 35.53, and 43.11% compared with E-LEACH, PEGASIS-E, LEACH-1R PEGASIS and P-LEACH algorithms. The average energy consumption per round of the ICCHR algorithm is lower than E-LEACH, PEGASIS-E, LEACH-1R PEGASIS and P-LEACH algorithms about 4.73, 9.04, 35.60, and 43.31%. This research can provide theoretical references for the orchard complex environment wireless networking. تتمتع عقد شبكة المستشعرات اللاسلكية بطاقة محدودة، وأصبحت كيفية استخدام الطاقة المحدودة بكفاءة لتحقيق نقل البيانات الفعال موضوعًا ساخنًا. بالنظر إلى خصائص زراعة البساتين في الصفوف والظل الناجم عن الميزات العشوائية المتفرقة، لتحسين كفاءة استخدام الطاقة لشبكة استشعار البساتين اللاسلكية وإطالة عمر الشبكة، نقترح خوارزمية محسنة للتوجيه الهرمي للتجميع القائم على السلسلة (ICCHR) بناءً على خوارزمية الرشح. تبحث خوارزمية المركز الدولي لحقوق الإنسان في تشكيل المجموعات واختيار رؤساء المجموعات وتشكيل السلسلة بالإضافة إلى عملية نقل البيانات، وتمت محاكاتها بشكل أكبر باستخدام خوارزميات E - LEACH و PEGASIS - E و LEACH -1R PEGASIS و P - LEACH من خلال MATLAB. تظهر نتائج المحاكاة أنه بالنسبة لـ BS عند (50، 175)، من وجهة نظر جميع مقاييس موت عقد المستشعرات، فإن عمر الشبكة لخوارزمية ICCHR يمتد إلى حوالي 3.29 و 8.78 و 35.53 و 43.11 ٪ مقارنة بخوارزميات E - LEACH و PEGASIS - E و LEACH -1R PEGASIS و P - LEACH. متوسط استهلاك الطاقة لكل جولة من خوارزميات المركز الدولي لحقوق الإنسان أقل من خوارزميات E - LEACH و PEGASIS - E و LEACH -1R PEGASIS و P - LEACH حوالي 4.73 و 9.04 و 35.60 و 43.31 ٪. يمكن أن يوفر هذا البحث مراجع نظرية لبيئة البستان المعقدة للشبكات اللاسلكية.

In the current situation with the unprecedented deployment of clean technologies for electricity generation, it is natural to expect that storage will play an important role in electricity networks. This paper provides a qualitative methodology to select the appropriate technology or mix of technologies for different applications. The multiple comparisons according to different characteristics distinguish this paper from others about energy storage systems. Firstly, the different technologies available for energy storage, as discussed in the literature, are described and compared. The characteristics of the technologies are explained, including their current availability. In order to gain a better perspective, availability is cross-compared with maturity level. Moreover, information such as ratings, energy density, durability and costs is provided in table and graphic format for a straightforward comparison. Additionally, the different electric grid applications of energy storage technologies are described and categorised. For each of the categories, we describe the available technologies, both mature and potential. Finally, methods for connecting storage technologies are discussed.

Massive adoptions of combined heat and power (CHP) units necessitate the coordinated operation of power system and district heating system (DHS). Exploiting the reconfigurable property of district heating networks (DHNs) provides a cost-effective solution to enhance the flexibility of the power system by redistributing heat loads in DHS. In this paper, a unit commitment considering combined electricity and reconfigurable heating network (UC-CERHN) is proposed to coordinate the day-ahead scheduling of power system and DHS. The DHS is formulated as a nonlinear and mixed-integer model with considering the reconfigurable DHN. Also, an auxiliary energy flow variable is introduced in the formed DHS model to make the commitment problem tractable, where the computational burdens are significantly reduced. Extensive case studies are presented to validate the effectiveness of the approximated model and illustrate the potential benefits of the proposed method with respect to congestion management and wind power accommodation. (Corresponding author:Hongbin Sun)

Robust mitigation options will play significant role in achieving the target of limiting global change to below 1.5 °C above pre-industrial levels by 2100. To support cooperation for mitigation development, we establish a real options-based model to evaluate the rational decisions of exercising the abandon option for carbon capture and storage-enhanced oil recovery (CCS-EOR) projects under oil market and geological uncertainties. Three possible cooperative mechanisms (fixed carbon dioxide (CO2) price, oil-indexed CO2 price, and joint venture contracts) among CO2-EOR stakeholders are evaluated. The results show that the conflicts in profit maximization targets for different stakeholders in cooperative mitigation are to a great extent unable to be avoided. A joint venture business model is preferred in cooperative mitigation as it can effectively weaken such conflicts. And it is more reasonable to provide incentives to the downstream of the CO2-EOR chain than compensating the adoption cost of carbon capture technologies in the upstream. From a global perspective, the inefficient cooperation can be a main barrier that hinders the development of deep-cutting options. Global mitigation strategies should not only focus on promoting technology progress but also the design of innovative business models to balance the benefits among stakeholders. A joint venture business model is recommended in both the developed and developing countries for seizing the early mitigation opportunities.

Abstract The potential of using high metals containing coal gangue and lignite to prepare high-activity coal char-based catalysts is investigated for effective biomass tar decomposition. Loose structure and rough surface are formed for these char-based catalysts with heterogeneous distribution of a large number of inorganic particles. In the biomass tar decomposition, the performance of the coal char-based catalysts is significantly influenced by the content of the metals in the raw materials and coal gangue char (GC) with the ash content as high as 50.80% exhibits the highest activity in this work. A high biomass tar conversion efficiency of 93.5% is achieved at 800 °C along with a significant increase in the fuel gas product. During the five-time consecutive tests, the catalytic performance of GC increases a little at the second or third times reuse and remains relatively stable, showing the remarkable stability of the catalyst in biomass tar decomposition applications.

Abstract This article introduces an effective stochastic operation framework for optimal energy management of the shipboard power systems including large, nonlinear and dynamic loads. The proposed framework divides the ship power system into several agents, which coordinate with each other based on their demands/supplies until. The alternating direction method of multipliers (ADMM) is deployed as the multi-agent framework to solve the reformulated distributed energy management problem in the ship. Two types of turbo-generators are considered in the proposed system model, including single-shaft and twin-shaft models, to increase the part-load efficiency in certain times when facing variable speed operation. The proposed distributed framework is equipped with a recursive mechanism, which helps the ship system for running optimal load scheduling when facing insufficient power generation. In order to model the uncertainty effects associated with the forecast error in the interval-ahead load demand, a stochastic framework based on unscented transform is devised which can work in the nonlinear and correlated environments of shipboard power systems. Due to the nonlinear cost function in each agent, a powerful optimization algorithm based on modified θ-firefly algorithm (Mθ-FOA) is proposed. This is a phasor algorithm, which helps for escaping from premature convergence and getting trapped in local optima. The appropriate performance of the proposed stochastic model is examined on the real dataset of a ship power system. The simulation results show the high robustness, guarantied consensus, economic operation and feasible solution when power generation shortage based on load shedding in the system.

Abstract Liquid fuels are likely to remain the main energy source in long-range transportation and aviation for several decades. To reduce our dependence on fossil fuels, liquid biofuels can be blended to fossil fuels – or used purely. In this paper, coconut methyl ester, standard diesel fuel (EN590:2017), and their blends were investigated in 25 V/V% steps. A novel turbulent combustion chamber was developed to facilitate combustion in a large volume that leads to ultra-low emissions. The combustion power of the swirl burner was 13.3 kW, and the air-to-fuel equivalence ratio was 1.25. Two parameters, combustion air preheating temperature and atomizing air pressure were adjusted in the range of 150–350 °C and 0.3–0.9 bar, respectively. Both straight and lifted flames were observed. The closed, atmospheric combustion chamber resulted in CO emission below 10 ppm in the majority of the cases. NO emission varied between 60 and 183 ppm at straight flame cases and decreased below 20 ppm when the flame was lifted since the combustion occurred in a large volume. This operation mode fulfills the 2015/2193/EU directive for gas combustion by 25%, which is twice as strict as liquid fuel combustion regulations. The 90% NO emission reduction was also concluded when compared to a lean premixed prevaporized burner under similar conditions. This favorable operation mode was named as Mixture Temperature-Controlled (MTC) Combustion. The chemiluminescent emission of lifted flames was also low, however, the OH* emission of straight flames was clearly observable and followed the trends of NO emission. The MTC mode may lead to significantly decreased pollutant emission of steady-operating devices like boilers, furnaces, and both aviation and industrial gas turbines, meaning an outstanding contribution to more environmentally friendly technologies.