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The high-frequency vibration problem of structures seriously affects the service safety，reliability and comfort of the aircraft. It is of great academic value and engineering significance to predict the high-frequency vibration response of structures efficiently and accurately. The energy finite element method（EFEM）is a new method developed in recent years to predict high-frequency vibration response. It overcomes the shortcomings of traditional methods such as the finite element method（FEM）and the statistical energy analysis（SEA）in predicting highfrequency vibration response. In this paper，the research progress of the energy finite element method in recent years is reviewed. The basic theory of the energy finite element method and its extension and application in enginee ring are elaborated. Studies of the energy finite element method in predicting the high-frequency vibration response of aircraft structures are introduced. In addition，the future directions of the energy finite element method are prospected.

The role of keystone species in maintaining ecosystem stability is a crucial aspect of ecology. Identifying key mammalian species within an ecosystem requires a systematic approach, utilizing criteria and indicators derived from species characteristic variables. This study presents a framework to identify key mammalian species based on various ecological, structural, and functional factors. By developing a mechanistic model of energy flow in food webs and trophic levels, the model aims to pinpoint each species’ role in the stability and sustainability of biomass flow within the ecosystem. Known as KVT version 1.0, the model explains the role of each characteristic variable of mammalian species, predicts population growth, elucidates species interactions at trophic levels, and assesses species-specific dietary compositions, including food requirements, reproduction, and activity. Factor analysis of model outputs has produced equations to determine the value of keystone species (Kv), indicating the role of mammalian species in the stability and sustainability of biomass flow in the ecosystem. Keystone species, as identified by this model, are primarily small mammals of the families Muridae, Sciuridae, Tupaiidae, Ptilocercidae, Hystricidae, Viverridae, and Herpestidae, demonstrating omnivorous and herbivorous trophic levels. This model can serve as a valuable framework for conservation management of biodiversity in an ecosystem, with potential for expansion to include characteristics of non-mammalian species in future research.

This study aimed to assess the roles and contributions of various joint (ankle, knee, hip, shoulder, elbow and wrist) during overhead volleyball passing across different distances. Eight male college volleyball players performed passes into a floating target set at 2.53 meters height from three different distances (2.5, 5 and 7.5 meters) with their feet remaining on the ground. Motion and force data were collected from three successful passes per player. Using inverse dynamics methods, we analyzed kinetic variables at each joint to determine energy generation and transfer. The findings revealed that the energy transfer through the shoulder joint to the arm varied with distance, with significant differences in the upper limb energy generation between the short and medium distances (p < 0.001). The study concluded that precise control and adjustment of the upper limb are crucial for short and medium distance passes, while lower limb contributions, including stabilization and extension play a vital role in executing long-distance passes.

Climate change has intensified urban heat risks through extreme heat and heat island effects. Using Fuzhou as a case study, we conducted assessments of heat risk and cool island quality to identify core heat risk sources (CHRSs) and core cold sources (CCSs). Based on the degree of resistance to surface heat transfer, we constructed a comprehensive resistance surface. This was followed by the construction of a composite cooling network using the minimal cumulative resistance and circuit theory models, along with the identification of key nodes to enhance the protection of cool island resources and ensure network stability. Our findings revealed that the central urban area had the highest heat risk, followed by the eastern coastal areas, showing a trend of further expansion towards the southeastern coast. Relatively high-quality cool island resources were distributed in the western mountainous area. We identified 21 CHRSs and 32 CCSs. The composite cooling network included 94 heat transport corridors and 96 cool island synergy corridors, with 148 cooling nodes and 78 barrier nodes. The average land surface temperature of transport and synergy corridors was 27.89°C and 25.34°C, respectively, significantly lower than the high-risk areas (31.14°C). Transport corridors enable heat transfer from CHRSs to CCSs, while synergy corridors can achieve further cooling by enhancing the synergy among cool islands.

Abstract Astaxanthin biosynthesis in Haematococcus pluvialis is driven by energy. However, the effect of the flagella-mediated energy-consuming movement process on astaxanthin accumulation has not been well studied. In this study, the profiles of astaxanthin and NADPH contents in combination with the photosynthetic parameters with or without flagella enabled by pH shock were characterized. The results demonstrated that there was no significant alteration in cell morphology, with the exception of the loss of flagella observed in the pH shock treatment group. In contrast, the astaxanthin content in the flagella removal groups was 62.9%, 62.8% and 91.1% higher than that of the control at 4, 8 and 12 h, respectively. Simultaneously, the increased Y(II) and decreased Y(NO) suggest that cells lacking the flagellar movement process may allocate more energy towards astaxanthin biosynthesis. This finding was verified by NADPH analysis, which revealed higher levels in flagella removal cells. These results provide preliminary insights into the underlying mechanism of astaxanthin accumulation enabled by energy reassignment in movement-lacking cells.

In China, the introduction of Chinese mitten crabs Eriocheir sinensis into saline-alkali rice fields has improved both soil utilization and quality. To promote the development and adoption of this novel rice-cropping mode, this study developed Ecopath models for two contrasting systems, rice-crab integrated farming (RC) and rice monoculture (R). Each system’s trophic structure, energy flow, and carrying capacity were analyzed and evaluated. The results showed that introducing Chinese mitten crabs increased both the biomass and utilization of rice, with its biomass 4.81 % higher in the RC than R system, with an ecological efficiency value that was 0.15 higher. Both systems exhibited similar trophic structures with three integer trophic levels. Total system throughput in the RC system was 21 368 g m−2 130 days−1, exceeding the 13 730 g m−2 130 days−1 in the R system. The ratio of total net primary production to the sum of all respiratory flows in the RC system was 2.390, this lower than the 4.006 in the R system, indicating that the former’s scale and development degree surpass the latter’s. In the RC system, Chinese mitten crabs primarily utilized detrital energy, with the energy flowing from detritus to trophic level II accounting for 41.84 % of the total energy input into the detritus group; that value is much higher than the 27.15 % in the R system. The carrying capacity of crabs was 33.66 g m−2. Overall, after polyculture with Chinese mitten crabs and the addition of feed, the rice farming system’s trophic structure did not change significantly, yet more energy was directed towards production, and the current polyculture ratio is reasonable. This study not only provides scientific evidence for the development of the rice-crab integrated farming model in saline-alkali soils, but also enriches the application potential of food web modeling in integrated rice-fish farming systems.

Artificial light at night (ALAN) is exerting growing pressure on natural ecosystems, but its impact on biological interactions remains unclear. This study aimed to assess how ALAN influences leaf functional traits and herbivory in two prevalent street tree species (Styphnolobium japonicum (L.) Schott and Fraxinus pennsylvanica) through field surveys and paired experiments in the urban areas of Beijing, China. We found that ALAN led to increased leaf toughness and decreased levels of leaf herbivory. Additionally, ALAN showed species-specific effects on leaf nutrients, size as well as defense substances. The findings illustrate that ALAN can significantly alter some key functional traits and ecological processes (nutrient cycling, energy flow). In general, we suggest that high ALAN intensity will be detrimental to the energy flow from urban plants to higher trophic levels, posing a potential threat to the maintenance of biodiversity (e.g., arthropod diversity, bird diversity) in urban ecosystems.

The series-parallel hybrid system has attracted much attention from scholars for its effective integration of the power advantages and operating characteristics of different power sources, which is influenced by international emission regulations, energy-saving and emission reduction policies. As such, a series-parallel hybrid powertrain is introduced to the amphibious vehicle, and an innovative powertrain topology architecture is proposed. Meanwhile, the operation mode and energy efficiency characteristics are investigated during the working process. Firstly, the energy flow simulation model of a series-parallel gas-electric hybrid propulsion system is constructed using a modular modeling approach. Secondly, four operating modes, namely mechanical propulsion, electric propulsion, hybrid propulsion and charging mode, were formulated due to the fact that the propulsion system has multiple forms of power sources in the form of natural gas engine and reversible motor. Meanwhile, the energy flow states were investigated under different operating modes. Meanwhile, a comprehensive investigation of the energy efficiency associated with propulsion, storage and start-up energy was conducted for each specific mode. The results of the research indicated that the energy efficiency of the electric propulsion mode can reach up to 35.15 %, which is the gain from the wide operating range of the motor's high efficiency. The hybrid propulsion mode can obtain the highest energy efficiency of 35.88 %, which fully demonstrates the advantages of coordinating and complementing the two power sources, the natural gas engine and the reversible electric motor. This investigation also provides theoretical and empirical support for optimizing energy matching and formulating energy management strategies.

Substantial research exists on predation and its ecology. Most research has focused on durophagous fishes, brachyuran crabs, and lobsters. Data are lacking, however, on soft-bodied predators like anemones, and their contribution to overall levels of predation remains largely unevaluated. Here, we compared predation rates of the durophagous predator, the crab C. maenas and the soft-bodied predator, the anemone Actinia equina on 15 intertidal shores around Anglesey, north Wales, UK. We employed a novel approach to assess predation based on measuring faecal output from recently collected individuals and converting it to food consumed using absorption efficiencies (AEs) measured using potential prey species inhabiting the same shores. Anemone mean abundance was 8.21 (± 0.27, s.e.) individuals.m−2, whereas for C. maenas it was 0.23 (± 0.02, s.e.) individuals.m−2. AEs when fed mussel tissue, a polychaete worm, or a shrimp were 92.8–94.0% in C. maenas and 40.5–95.8% in A. equina. This difference in values reflected the different feeding modes of the two predators. Unexpectedly, A. equina consumed 3.5–7 times more prey than C. maenas. The consumption of larger amounts of prey by an anemone than the dominant durophagous predator has important consequences for calculating energy flows in food webs, understanding predation controls in assemblages, and potentially for wider predation trends.

This paper explores the generation of coherent electromagnetic energy flows to form a shock wave in free-space as a linear medium. Flows of energies from several waves need to build up coherently to create the wave. In free-space, energy in the propagation direction flows at speed of light and therefore cannot match the required energy accumulation. Electromagnetic waves carrying orbital angular momentum are suggested instead of ordinary plane waves because they have a controllable energy flow in the transverse direction of propagation. Flows of several waves are managed under certain conditions to accumulate energy and create a shock wave in the transverse direction. These conditions must be maintained to preserve the waveform during propagation. Previous studies on acoustical shock waves in a nonlinear medium explained the effect of nonlinear medium on the wave. Nonlinear effects are implemented to create similar propagation conditions in the linear medium and to preserve the waveform. The wave, however, rotates and expands during propagation due to the evolution of its internal energies. Internal energy flows are studied, and an analogy is drawn with flows in fluids. Numerical simulations are conducted to support the theoretical derivations on wave generation and propagation.

Pyrolysis is a mainstream technology for biomass energy utilization, but theoretical simulation, verification feedback on the coordinated pyrolysis process, material conversion rules, and energy efficiency characteristics of multi-source biomass wastes, particularly Chinese medicinal residue, arestill relatively scarce. In this paper, Aspen Plus industrial simulation software with a complete physical property system was used to establish a simulation model for biomass waste pyrolysis to produce carbon, and its reliability was verified. The actual pyrolysis process data of waste pine wood from agricultural forest source were systematically simulated, the material flow and energy flow during the pyrolysis process of the sargentgloryvine stem medicine residue was analyzed, and the conversion efficiency was comprehensively evaluated. The results showed that the energy consumption of the pyrolysis system was 2580.7 MJ/h, and the energy efficiency was 53.0% under the current single waste condition. At temperatures ranging from 500 to 550 ℃, 30%~60% of traditional sargentgloryvine stem medicine residue was simulated to be incorporated into the collaborative pyrolysis, which resulted in optimal material recycling efficiency and energy efficiency. The system′s energy consumption was reduced by 30%~60%, and the energy efficiency of the system increased by 3.0%~6.0%, which could provide scientific basis for the collaborative pyrolysis of Chinese medicine residue.

This study proposed an energy consumption input–output (ECIO) model, which contributed to identifying the roles in energy consumption of all sectors of a certain country or region. Taking all Chinese sectors as an example, this study measured and analyzed the energy consumption flows in all Chinese sectors over 2002–2018 by combining the ECIO model and the modified hypothetical extraction method. The results show that the construction sector was the largest energy receiver in the economic system. Its dependence on other sectors was the strongest and maintained a remarkable growing trend year by year. Specifically, the amounts of energy flow from the other seven sectors to the construction sector in 2002 were 1,128, 2,844, 17,705, 2,556, 524, 2,335, and 579 × 104 tce (1 tce = 29.3 GJ), respectively. They increased to higher amounts of 1,860, 9,061, 74,557, 9,234, 2,865, 10,519, and 3,784 × 104 tce in 2018, respectively. The manufacturing sector as the largest energy supplier was the most dependent on itself, and played the most significant role in China’s economic system. More precisely, the amounts of energy flow from the manufacturing sector to the other six sectors in 2002 were 3,347, 382, 17,705, 3,569, 1,517, and 11,467 × 104 tce respectively. They increased to 3, 434, 1,339, 9,234, 5,885, 3,633, and 38,727 × 104 tce in 2018, respectively. The mining sector has the most paths of energy export for the production and development of other sectors.

Based on the field survey and reference data of the sea area of the Zhongjieshan Islands from 2021 to 2022, the Ecopath model was used to analyze the energy flow structure of the marine ecosystem of the sea area of the Zhongjieshan Islands; the energy structure of the marine ecosystem was divided into 21 functional groups, and its nutrient structure, energy flow, and total system characteristics were analyzed. The results show that the credibility of the model is 0.414, which is at a medium level. The trophic level of each functional group of the ecosystem in the sea area of Zhongjieshan Islands was 1–3.48, the energy flow structure of the system was mainly concentrated in the first five grades, and the trophic level was relatively simple, with the average energy transfer efficiency of the system being 8.11%, the energy flow range being 2.81–13.04%, the energy transfer efficiency of the primary producers of the system being 7.25%, and the energy conversion efficiency of the system debris being 9.12%. The total system throughput was 2125.96 t·km−2; The analysis of the overall characteristics of the ecosystem showed that the system connectance index and the system omnivory index were 0.45 and 0.24, respectively, while the Finn’s cycling index was 8.24, the Finn’s mean path length of the system was 2.72, and the total primary production/total respiration was 1.71. In this study, the marine ecosystem model of the sea area of the Zhongjieshan Islands was studied to understand the trophic structure and ecosystem status of the sea area, which is conducive to the sustainable utilization and scientific management of fishery resources in the sea area.

Hybrid electric aircraft use traditional engine and electric propulsion combinations to optimize aircraft architecture, improve propulsion efficiency, and reduce fuel consumption. As a new technology, the fuel and energy consumption calculation of hybrid electric aircraft is more complicated than traditional aircraft due to the usage of different energy forms. The purpose of this paper is to develop the analytical method for fuel and energy consumption for hybrid electric aircraft. This paper summarizes the working principle of hybrid electric aircraft, including the system architecture and power conversion mechanism. The calculation of fuel and energy consumption for hybrid electric aircraft is carried out in detail. In order to evaluate large hybrid electric aircraft, the architecture, based on energy flow, is established, and turbofan engine, electrical system, electric duct fan, and aerodynamic model characteristics are established. With a single-aisle aircraft as an example, the fuel and energy consumption under the 800 nautical mile range is performed. It shows that fuel consumption can be reduced by 10% and energy consumption by 4.7% compared with a traditional aircraft. The effects of different range and battery ratios are analyzed. The payload range for the hybrid electric aircraft is analyzed. The results show that even though the hybrid electric aircraft reduces the payload and range, it can significantly reduce fuel and energy consumption.

This paper presents a novel method for generating and shaping reverse energy flow through the interference of light fields from a minimal number of point light sources. Until now, reverse energy flow has only been observed using complex light fields, such as optical vortices or cylindrical vector beams, limiting the formation of reverse energy flow near the optical axis. We demonstrate both analytically and numerically that unbounded regions of reverse energy flow can be achieved with just two point light sources, positioned asymmetrically at specific angles (e.g., 90 or 45 degrees) and with particular polarization states. The results indicate that the relative reverse energy flow can be enhanced by increasing the number of sources to three or four, adjusting their polarization, or introducing a vortex phase singularity. The presence of an initially embedded asymmetry in the fields under consideration leads to the formation of a non-uniform distribution of spin and orbital angular momentum density. Variations in the polarization state, as well as the introduction of a vortex phase singularity, allow for changing the distribution of angular momentum density while maintaining the presence of a reverse energy flow. We also explore the feasibility of implementing the obtained results using sectional phase diffractive optical elements, which will enhance the energy efficiency of the generated fields compared to point sources.

With the increase of new energy penetration, the power balance and frequency stability problems brought by its randomness, intermittency and volatility has become increasingly serious. It is difficult to cope with these problems only by traditional centralized power plants. Flexible resources in the power systems should also bear a part of the responsibility for the balance of power and energy. Virtual power plant (VPP) can aggregate a large number of distributed flexible resources with different characteristics, participate in the electricity markets as a whole and accept the dispatch of the grid, and provide important support for the real-time power balance of the power systems. The development of VPPs should be based on a large number of flexible resources, advanced communication and dispatching/control technologies, and efficient business models and good market policies. The operation of VPPs can be attributed to the energy flow of the energy network, the information interaction of the information network and the value transfer of the value network. Therefore, based on the three-layer network architeciture of “energy-information-value”, the operation modes and control schemes of different types of VPPs were analyzed, and the idea of “three flow separation-convergence” for VPP architecture design was proposed. The findings provide useful guidance for the design, construction and operation of VPPs.

Abstract Aquatic macrophytes are the main autochthonous component of primary production in the Amazon Basin. Floating meadows of these plants support habitats with highly diverse animal communities. Fishes inhabiting these habitats have been assumed to use a broad range of food items and compose a particular food web. We employed carbon (δ13C) and nitrogen (δ15N) stable isotope analysis to draw the trophic structure of these habitats and to trace the energy flow by its trophic levels. Fishes and other animals from 18 independent macrophyte meadows of a floodplain lake of the Solimões River (Amazonia, Brazil) were analyzed. The food web of macrophyte meadows consists of four trophic levels above autotrophic sources. In general, primary consumers exhibited a broader range of food sources than the upper trophic levels. Some fish species depended on a large number of food sources and at the same time are consumed by several predators. The energy transfer from one trophic level to the next was then mainly accomplished by these species concentrating a high-energy flux and acting as hubs in the food web. The broad range of δ13C values observed indicates that the organisms living in the macrophyte meadows utilize a great diversity of autotrophic sources.

The evaluation of energy input and output processes in agricultural systems is a crucial method for assessing sustainability levels within these systems. In this research, the investigation focused on the input and output energies and related indices in sunflower farms in Khoy County during the agricultural year 2017–2018. Data were collected from 140 sunflower producers through specialized questionnaires and face-to-face interviews. Additionally, artificial neural networks (ANNs), specifically the multilayer perceptron, were employed to predict the output energy. The results revealed that a substantial portion of the total input energy was attributed to chemical nitrogen fertilizer (43.98%), consumable fuel (25.74%), and machinery (8.42%). The energy efficiency (energy ratio) in these agroecosystems was relatively low, measured at 1.57 for seed and 7.96 for seed and straw. These values should be improved. The energy efficiency in seed production was computed at 0.06 MJ·ha−1, while, for the combined seeds and straw, it was 0.57 MJ·ha−1. In particular, seed energy efficiency represents approximately 11% of the overall biological energy efficiency, highlighting that a substantial 89% of the produced energy is associated with straw. The proper use of this straw is crucial, as its improper handling could lead to a drastic decrease in overall efficiency. Furthermore, the explanatory coefficient (R2) and the mean absolute percentage error (MAPE) to predict the output energy with the best neural network were 0.94, and 1.77 for the training data, 0.97 and 1.55 for the test data, and 0.9 and 2.08 for the validation data, respectively; additionally, 0.97 and 0.42 were obtained by an ANFIS.

In order to characterize the energy flow and trophic structure of a polyculture pond that contained Litopenaeus vannamei and Tegillarca granosa, we used an Ecopath with Ecosim (EwE) model. We constructed the EwE model using 13 functional groups including L. vannamei, T. granosa, macrozooplankton, microzooplankton, microbenthos, bacterioplankton, benthic bacteria, micro-phytoplankton, nano-phytoplankton, pico-phytoplankton, artificial feed, detritus in water, and detritus in sediment. Our findings showed that this polyculture ecosystem contained five trophic levels and that two of them accounted for 99.41% of the total system throughput. L. vannamei, microbenthos, and detritus in sediment displayed high ecotrophic efficiency (EE) values, while artificial feed held relatively low EE implying that the artificial feed was used inefficiently. The bacteria including benthic bacteria and bacterioplankton was inefficiently used. The main energy flows were associated with artificial feed, phytoplankton, and detritus in this polyculture system. The compatibility of L. vannamei and T. granosa was high according to the mixed trophic impact analysis. In conclusion, the study showed that this polyculture ecosystem still needed to be improved in the aspects of energy consumption. It would be necessary for this polyculture ecosystem to perform further optimization and enhancement on the energy utilization efficiency and comprehensive benefits.

Understanding the distinct functions of human muscles could not only help professionals obtain insights into the underlying mechanisms that we accommodate compromised neuromuscular system, but also assist engineers in developing rehabilitation devices. This study aims to determine the contribution of major muscle and the energy flow in the human musculoskeletal system at four sub-phases (collision, rebound, preload, push-off) during the stance of walking at different speeds. Gait experiments were performed with three self-selected speeds: slow, normal, and fast. Muscle forces and mechanical work were calculated by using a subject-specified musculoskeletal model. The functions of individual muscles were characterized as four functional behaviors (strut, spring, motor, damper), which were determined based on the mechanical energy. The results showed that during collision, hip flexors (iliacus and psoas major) and ankle dorsiflexors (anterior tibialis) were the most dominant muscles in buffering the stride with energy absorption; during rebound, the posterior muscles (gluteus maximus, gastrocnemius, posterior tibialis, soleus) contributed the most to energy generation; during preload, energy for preparing push-off was mainly absorbed by the muscles surrounding knee (vastus, semimembranosus, semitendinosus); during push-off, ankle plantar flexors (gastrocnemius, soleus, posterior tibialis, peroneus muscles, flexor digitorum, flexor hallucis) mainly behaved to generate energy for forward propulsion. With increased walking speed, additional energy (almost 400%) from harder stride was mainly absorbed by the flexor muscles. Hip extensors and adductors transferred more energy (around 150%) to the distal segments during rebound. Soleus and gastrocnemius muscles generated more energy (about 75%) to the proximal segments for propulsion. Along with our previous study of joint-level energy analysis, these findings could assist better understanding of human musculoskeletal behaviors during locomotion and provide principles for the bio-design of related assistive devices from motors performance enhancement to rehabilitation such as exoskeleton and prosthesis.

Energy flux in food webs is a fundamental feature of ecosystems and an important link between biodiversity and ecosystem function. Studies of energy flow through the soil nematode food web have emerged in recent year; however, it is not clear whether and how the nematode food web structure affects the energy flow. In this study, the structures and carbon flux of soil nematode food webs in four different ecosystems, namely, forageland, cropland, secondary forest, and grass-shrubland, were assessed. The food web structure was represented by nematode community indices such as maturity index, structure index, genus and trophic group diversity, and slope of size spectra. The results showed that carbon flux through the nematode food webs was the highest and lowest in the secondary forest and forageland, respectively. The total carbon flux of nematode food web was higher in the cropland than that in the grass-shrubland. The magnitudes of bacterial and fungal energy channels were basically equal in the forageland and secondary forest. The energy flow through the bacterial channel was greater than that through the fungal channel in the grass-shrubland, whereas the pattern was reversed in the cropland. The total carbon flux through the nematode food web, the carbon fluxes through the bacterial or fungal channel, and the energy flow uniformity were positively correlated with the nematode structure index, maturity index, and genus diversity index. The trophic group diversity and size spectra slope of nematode communities were not significantly correlated with the carbon flux. The results indicate that mature and complex soil communities support high energy flux across soil food webs.

Aggravation of energy shortage and global warming has raised public low-carbon awareness and promoted the development of integrated energy system (IES). However, there has not been a general method for analysis of carbon emission distribution in the IES yet. A methodology combining energy flow (EF) with carbon emission flow (CEF) is proposed in this paper to calculate and analyze the carbon emission from the IES, which is composed of AC/DC power systems and heating/cooling systems. Decoupling methods are used to improve computing efficiency with good convergence in solving energy flow equations of subsystems. A typical case is modeled and simulated using CloudPSS-IESLab platform, a high-efficient power flow solver, with calculation results and Sankey diagram demonstrating the CEF distribution in the IES.

In line with the global green steel development, a steel enterprise seeks to reduce its energy consumption by building a scientific, effective evaluation and optimization model for steel manufacturing’s energy utilizations. It highlights the enterprise and the steel sector’s green mainstream. This paper proposes a dynamic evaluation model for energy flow network operations and brings forward evaluation indicators based on analyses of each energy flow’s input and output, and utilization, conversion and loss during the steel manufacturing process. They provide support for making dynamic optimizations for the energy flow network to achieve an optimal operation efficiency. As a result, an optimization model for energy flow network operations has been built and plays a part in guiding the steel enterprise to contribute further to energy conservation and consumption reduction.

To explore ways to improve the effective thermal efficiency and fuel economy of heavy-duty vehicles, the vehicle energy flow test was conducted under Chinese-World Transient Vehicle Cycle (C-WTVC). According to the data of the test, the distribution law of transient energy flow was analyzed. The results show that the energy flow distribution of the diesel-powered heavy-duty vehicle is mainly influenced by vehicle operating conditions. The percentages of effective power, exhaust energy flow, coolant energy flow, pump loss energy flow and other loss of the vehicle under C-WTVC are 35.7%, 35.08%, 19.64%, 2.05% and 7.52%, respectively. The variable range of various energy flow is particularly high due to the vehicle’s frequent acceleration and deceleration under C-WTVC. The phenomenon of ”oil break” will cause fuel energy flow, exhaust energy flow, and effective power to plummet to near zero during the sudden deceleration period. At this time, the percentage of pump loss energy flow and coolant energy flow will increase sharply. As a result, a reasonable fuel injection strategy during vehicle acceleration can effectively reduce the variation between cycles, thus improving the effective thermal efficiency and fuel economy. In addition, the waste heat loss of coolant and exhaust energy flow has a great utilization space.

Abstract Based on the energy flow analysis method, this paper establishes the relationship between the heat accumulator and the thermal system from the perspective of heat transfer. Different types of heat accumulators are converted into different equivalent models based on energy flow, the existing sneak circuit analysis methods based on energy flow are optimized, and the starting point and end point of path search are redefined. The energy flow‐based correlation method proposed in this paper is applied to a system with two different types of heat accumulators. The results show that the sneak circuit analysis method based on energy flow proposed in this paper can search for more paths and discover new sneak circuits on the basis of the original method. Therefore, the new method is feasible and effective.

To achieve carbon neutrality and address global energy supply issues by 2050, there is active progress in the industrial sector for waste energy recovery and commercialization projects. It is necessary to consider both the energy recovery efficiency and economic feasibility based on the production volume for the resource utilization of waste energy, along with eco-friendly processing methods. In this study, a waste heat recovery system was designed to recover a large amount of thermal energy from high-temperature exhaust gases of gas engines for power generation by using biogas produced from organic waste in industrial complexes. Types and sizes of components for a waste heat recovery system that were suitable for various engine sizes depending on biogas production were designed, and the energy recovery efficiency was analyzed. The waste heat recovery system consisted of a smoke tube boiler that generated superheated steam at 161 °C under 490 kPa of pressure from the exhaust gas as the heat source, along with two economizers for heating both supply water and hot water. Heat exchangers that were suitable for three different engine sizes were configured, and their performance and energy flow were calculated. In particular, when operating two engines with a power output of 100 kW, the boiler showed the highest steam production efficiency, and the superheated steam production from high-temperature exhaust gas at 600 °C was designed to be 191 kg/h, while hot water at 58 °C was designed to be produced at 1000 kg/h. In addition, further research on the heat exchanger capacity ratio confirmed that it was within a certain range despite the difference in heat exchanger capacity and efficiency depending on the engine size. It was confirmed that the heat exchange capacity ratio of the boiler was important as an optimal-capacity design value for the entire system, as it ranged from 46% to 47% of the total heat exchanger size.

The results of experimental studies of energy fluxes released during the diode target blow-up initiated by a high-current relativistic electron beam are presented in the paper. The energy of target explosion products required for realization of the observed diode structural elements deformation is being estimated. Measurements of the target explosion products parameters and finite-element modeling of the mechanical deformation of the cathode system elements show an energy release during the target explosion that far exceeds the energy input.

IntroductionSediment and nutrients flow into estuary with runoff, and then influence the estuary ecosystem. Much work has been done for investigating the response of water quality and species group (eg. phytoplankton or zooplankton) to the runoff from upstream, while few research has been taken to evaluate the response of the whole ecosystem.MethodsFood webs of different seasons and regions were established based on stable isotope analysis and Bayesian mixing model. The influences of upstream runoff and sediment transport on the estuarine food webs were analyzed.ResultsFood web in estuary had highly spatial-temporal variability. The stable isotope values of organisms were higher on the northern shore than that on the southern shore. The area with high-turbidity freshwater inflow nurtured more terrestrial- organic- matter (TOM) relying species. And the contribution of TOM to food web was higher in flood season than that in non-flood season. The trophic levels of major consumers in the non-flood season were generally higher than that in the flood season. Significant differences in the average TP of species between two shores appeared during the non-flood season (P < 0.05). Expect for the C value, all of the topological indexes of food webs on the northern shore were higher than those on the southern shore, and they were higher in the flood period.DiscussionThe input and diffusion of sediment and nutrients carried by runoff led to the changes in the dietary structure of estuarine organisms and the decrease in trophic levels of major consumers. At the same time, flow pulse with high sediment also aggravated the spatial differences of the structure of food webs. The higher contribution of TOM to consumers increased the link density of food web on the southern shore, making it a more robust system. However, the high diversity of food sources and aquatic species made the food web more complex on the northern shore.

At present, electrified railroads with complex road conditions are facing the problems of the existence of a single power supply method, the deterioration in power quality, and the difficulty in recycling regenerative braking energy. In order to improve the above problems, this paper establishes a traction power supply system containing photovoltaic units, proposes an optimized compensation model for the RPC (railroad power conditioner), and improves the particle swarm algorithm for solving the reference value of RPC compensation power. First, the structure of the RPC-based traction photovoltaic power generation system and the establishment of the integrated energy management strategy of the system are constructed. Then, the back-to-back converter compensation model with power quality index parameter constraints is established, which establishes the optimization function with the objectives of minimizing the negative sequence current, maximizing the power factor, and minimizing the RPC compensation power, as well as establishes constraints on the active converter capacity and three-phase voltage imbalance. Then, the particle swarm algorithm for solving the RPC compensation power reference value is improved, specifically in the original PSO by introducing dynamically changing inertia weights and learning factors. This not only solves the problem of the single power supply and realizes the nearby consumption of photovoltaic units in the traction system, but also realizes the recycling of regenerative braking energy and the coordinated control of the traction photovoltaic power generation system, improves the power quality of the system, and meets the demand of the RPC for real-time control. In order to verify the effectiveness of the optimized compensation model established in this paper and improve the convergence of the particle swarm algorithm for solving the RPC compensation power reference value, a simulation model of the traction PV power generation system is established in MATLAB/Simulink, and a real-time simulation is carried out to verify it based on the preset working condition data. The results show that the RPC optimization compensation model developed in this paper can coordinate the control system energy flow and improve the system power quality (the power factor increases and the negative sequence current decreases). The improved particle swarm algorithm is more convergent.

Abstract Global change alters ecological communities with consequences for ecosystem processes. Such processes and functions are a central aspect of ecological research and vital to understanding and mitigating the consequences of global change, but also those of other drivers of change in organism communities. In this context, the concept of energy flux through trophic networks integrates food‐web theory and biodiversity‐ecosystem functioning theory and connects biodiversity to multitrophic ecosystem functioning. As such, the energy‐flux approach is a strikingly effective tool to answer central questions in ecology and global‐change research. This might seem straight forward, given that the theoretical background and software to efficiently calculate energy flux are readily available. However, the implementation of such calculations is not always straight forward, especially for those who are new to the topic and not familiar with concepts central to this line of research, such as food‐web theory or metabolic theory. To facilitate wider use of energy flux in ecological research, we thus provide a guide to adopting energy‐flux calculations for people new to the method, struggling with its implementation, or simply looking for background reading, important resources, and standard solutions to the problems everyone faces when starting to quantify energy fluxes for their community data. First, we introduce energy flux and its use in community and ecosystem ecology. Then, we provide a comprehensive explanation of the single steps towards calculating energy flux for community data. Finally, we discuss remaining challenges and exciting research frontiers for future energy‐flux research.

In this study, the energy flow of an internal combustion engine (ICE) vehicle is experimentally investigated in a climate chamber under Worldwide Light-duty Test Cycle (WLTC). Each part of the tested vehicle energy loss has been compared to the similar displacement of engine or type of transmission according to the database of conventional gasoline engine passenger car. Then, an integrated simulation model for the tested vehicle is established and calibrated. After that, some technological pathways have been taken for tested vehicle fuel saving by using the calibrated simulation model. The specific fuel saving technological pathways mainly include excess air coefficient improving, engine speed decreasing when the engine resumed fuel supply, engine coolant temperature improving, engine coolant temperature rise process improving, transmission oil temperature and rise process improving, engine idle speed decreasing and transmission gear in neutral position when the vehicle speed is 0, electrical accessories power reducing, and engine cold start speed decreasing. The fuel saving degree of above technological scheme is 0.57%, 1.37%, 0.25%, 0.38%, 0.53%, 2.34%, 0.61%, and 0.59%, respectively. At last, the effects of combinatorial technological scheme to vehicle is simulated and experimented, and the fuel saving degree of them is 5.63% and 5.92%, respectively.

Abstract The trophic interactions between consumers and resources play a vital role in the stability of communities. In river systems, fragmentation of natural habitats and environmental changes alters the energy basis and community composition, consequently leading to variations in the community's trophic structure and niche space. However, our understanding of how the trophic structure responds to environmental changes is still very limited. Here, based on stable isotope data, we explored and compared trophic positions (TPs), community‐wide trophic metrics, and isotope niche space of fish communities in three reaches with different hydrogeomorphic conditions along a highly regulated subtropical river over three seasons. The community trophic structure and niche space showed notable spatiotemporal variations. Overall, the downstream reach had lower TPs, trophic diversity but higher trophic redundancy. The middle reach occupied a wider isotope niche space than other reaches, with the largest niche size during autumn. Furthermore, the niche overlap was relatively high in winter between reaches and in the downstream between seasons. The results implied a homogenization of feeding functional groups and energy flow pathways of species in the downstream community associated with the change of energy source and stability of hydrological conditions. The relationship between trophic structure and environmental factors suggested that the dam‐induced alteration in hydrological‐related aspects may drive the changes in the functional group composition, together with changes in energy basis, resulting in differences in the trophic structure of the community. The results of the present study deepen our understanding of how ecosystem functions respond to disturbance, thus contributing to improved ability to conserve river ecosystems.

Because of emissions of exhaust gases, global warming is proceeding, and air pollution has increased. Thus, many countries are manufacturing eco-friendly vehicles, including electric vehicles. However, the range of electric vehicles is less than the range of internal combustion engine vehicles, so electric vehicle production is being disrupted. Thus, it is necessary to analyze the energy flow of electric vehicles. Therefore, to analyze energy flow of electric vehicles, this study suggested an energy flow structure first, then modeled the energy flow of the vehicle, dividing it into battery, inverter and motor, reduction gear and differential, and wheel parts. This study selected a test vehicle, drove in urban driving conditions and measured data. Then, this study calculated energy flow using MATLAB/SIMULINK in real time, and calculated and analyzed energy loss of each of the vehicle’s parts using the calculated data.

In the present research, the energy flow of electric vehicle batteries under different environmental temperatures was experimentally examined in a climate chamber. The energy flow characteristics, energy loss conditions, and the critical components’ operating conditions and working efficiency under different environmental temperatures were comparatively analyzed. The test results show that the environmental temperature has a profound impact on an electric vehicle’s performance and the critical components’ working conditions. The driving mileage of the tested vehicle at −7 °C, 23 °C, and 35 °C was found to be 162.89 km, 256.09 km, and 198.69 km, respectively. The environmental temperature does not have much effect on the loss of the motor and motor control unit under driving conditions, and the proportion of those at different temperatures is in all cases about 18%. The battery-recycled energy at 23 °C under braking conditions is much higher than that at −7 °C and 35 °C, leading to a longer driving range. The power battery pack thermal transfer loss at −7 °C is much greater than that at 23 °C and 35 °C due to the low charging and discharging efficiency and the high energy consumption required to warm up the battery at a low environmental temperature. The compressor energy consumption accounts for a large proportion in both braking and driving conditions at 35 °C, and the proportions are 15.25% and 12.41%, respectively. The battery state-of-charge drops the fastest at −7 °C, followed by 35 °C, due to the differences in the power demands of air conditioning, warm air positive temperature coefficient (PTC), and battery PTC in high- and low-temperature environments. The working condition of the front motor under driving conditions at 35 °C is the most severe and leads to the lowest working efficiency.

Environmental pollution, disease transmission and food safety caused by intensive pond aquaculture is causing a bottleneck in its development, and a transformation to an integrated aquaculture model is the only way to achieve sustainable development. Integrated aquaculture practices require an evaluation index system that includes a set of ecological indicators that characterize ecosystem changes for use in benefit assessment. In this study, two Ecopath models, white shrimp Litopenaeus vannamei monoculture and integrated aquaculture using L. vannamei with the hard clam Mercenaria mercenaria, were constructed. Based on their representativeness and applicability, the 10 evaluation indicators output from the model were divided into four categories (trophic structure, niche competition, energy utilization and resistance to external disturbances) in order to construct an integrated aquaculture evaluation index system. The results showed that both the monoculture system and the integrated aquaculture system were composed of three integer trophic levels, with the highest effective trophic level being benthic (2.65). The effective trophic levels of L. vannamei in the monoculture and integrated aquaculture ecosystems were 2.03 and 2.02, respectively. The prey overlap index of L. vannamei and M. mercenaria in the integrated aquaculture ecosystem was 0.516, and M. mercenaria had a weak negative effect on L. vannamei. Functional groups with the highest ecotrophic efficiency (EE) values in the monoculture and integrated aquaculture systems were Artemia and microzooplankton, respectively. The EE values of phytoplankton, detritus and benthic bacteria in the integrated aquaculture system were higher than those in the monoculture system. The energy flowing to trophic level II and detritus accounted for 7.7% and 92.3% of the total primary production in the monoculture system, respectively, and accounted for 52.2% and 47.8% in the integrated aquaculture system, respectively. The calculated total net primary production/ total biomass (TPP/TB) and calculated total net primary production/ sum of all respiratory flows (TPP/TR) values of the integrated aquaculture system were lower than those of the monoculture system, while Finn’s cycling index (FCL) and Finn’s mean path length (FML) values were higher than those of the monoculture system. In general, compared with the monoculture system, the integrated aquaculture system showed no significant change in the trophic structure of each functional group, acceptable competition for ecological niches among cultured animals, substantially higher utilization of primary productivity and detritus, and greater system stability and resistance to disturbance. The integrated aquaculture evaluation index system provides a methodological basis for the development of new integrated aquaculture models and has implications for the evaluation of integrated aquaculture ecosystems.

Abstract Nutrient enrichment of rivers and lakes has been increasing rapidly over the past few decades, primarily because of agricultural intensification. Although nutrient enrichment is known to drive excessive algal and microbial growth, which can directly and indirectly change the ecological community composition, the resulting changes in food web emergent properties are poorly understood. We used ecological network analysis (ENA) to examine the emergent properties of 12 riverine food webs across a nutrient enrichment gradient in the Manawatu, New Zealand. We also derive Keystone Sensitivity Indices to explore whether nutrients change the trophic importance of species in a way that alters the resilience of the communities to further nutrient enrichment or floods. Nutrient enrichment resulted in communities composed of energy inefficient species with high community (excluding microbes) respiration. Community respiration was several times greater in enriched communities, and this may drive hypoxic conditions even without concomitant changes in microbial respiration. Enriched communities exhibited weaker trophic cascades, which may yield greater robustness to energy flow loss. Interestingly, enriched communities were also more structurally and functionally affected by species sensitive to flow disturbance making these communities more vulnerable to floods.

Fluorescent tubular ultraviolet lamps are used in medicine, industry, cosmetology, forensic science, and banking. During the development of the LED ultraviolet lamp in a T8 flask, a comparison of its lighting characteristics (power, energy flux, spectral distribution of radiation) with the parameters of special-purpose fluorescent lamps produced at industrial enterprises has been carried out. The design of the LED lamp includes a glass uviole tube with a diameter of 26 mm and a length of 322 mm (wall thickness is 1 mm, glass grade – SL97-3). For precise installation of the lamp in the irradiation facility and supplying electric power to it, plastic caps of the G13 pin type (the distance between the electrical contacts is 12.7 mm) are used. Measurements of electrical parameters, energy flux and spectral distribution of radiation have been carried out at nominal mains voltage on a Gooch &Housegophotocolorimetric measuring device. The developed LED lamp consumes seven times less electricity, has significantly longer (five times) expected service life and is a safer source of ultraviolet radiation, since it does not contain harmful vapors of mercury and its compounds. The LED ultraviolet lamp in a T8 flask can be used instead of the manufactured LUFT-10 lamps for special purposes, namely, in irradiators for carrying out technological processes (photochemical reactions, drying, curing), for attracting and disinsecting insects in traps, in photocopiers.

The comparison of trophic structure and energy flow between natural and artificial reefs is imperative to evaluate whether these man-made structures work similarly to comparable natural reefs. Here, to characterize the potential difference in functioning between two types of reef ecosystems, two trophic models (Ecopath) at an artificial reef and an adjacent natural reef on the coast of the north Yellow Sea, China, were established. Both Ecopath models were divided into 18 functional groups from primary producers (algae and phytoplankton) and detritus to predatory species (e.g., Sebastes schlegelii). Model outputs showed that the ecosystem scale was smaller in the artificial reef (total system throughput (TPP) = 6,455.47 t·km−2·year−1) relative to its natural counterpart (TPP = 9,490.48 t·km−2·year−1). At both reef types, a large proportion of energy occurred at trophic levels I and II, and most of the primary production was utilized through a detritus pathway. This result implies a bottom-up energy flow control for both cases. However, two types of reef systems were behaving in a reasonable manner, as mean transfer efficiencies were similar to the Lindeman efficiency (10%). The ecosystem maturity of the artificial reef is not comparable to that of the natural reef for its inferior value of total primary production/total respiration (TPP/TR). Moreover, both the connectance index (CI) and system omnivory index (SOI) were slightly higher at the artificial reef relative to the natural reef as well as other coastal systems with parallel latitudes, suggesting that the current artificial system has formed complicated interspecies relations and high-level stability. This work updates our knowledge about the functioning evolvement of established artificial reefs and provides a baseline for the efficient management of coastal zones and further investigations.

As an effective policy to revitalize rural land assets, land transfer is important to promote reforming rural land systems in poor areas. In this study, we integrated the energy systems language and emergy approach, quantified the energy flow process under the land transfer model, simulated the resource storage and energy flow state in the land transfer process, and finally compared and discussed the economic and ecological benefits of land transfer under different scenarios. The results show the following: (1) Economic benefits were significantly improved after the land transfer, and labor storage and infrastructure value were reduced. (2) Government investment enhanced the infrastructure value, and private investment led to a rapid reduction in labor storage. (3) Expanding apple orchards positively affected labor storage and infrastructure value and negatively influenced soil organic carbon storage and rural asset storage. (4) Land transfer behavior reduced the proportion of provisioning and supporting services and increased the proportion of regulating and cultural services. Overall, the research results are helpful for clarifying the complex mechanisms of the various components in the land transfer system and provide a scientific basis for the prediction and evaluation of land transfer in similar areas.

The design parameters are the most momentous factors in carrying out performance matching. For complex electromechanical products with a large number of design parameters, determining a set of critical design parameters which have a great influence on the performance is the premise of performance matching. In this paper, from a systematic perspective, a screening method of critical design parameters based on energy and a causal model is proposed. Since energy is the driving force of the product operation to achieve performance, the design parameters affect the performance through energy flow in the product. Therefore, the causal model among design parameters, characteristic energy, and performance is established, where its path coefficients are determined based on the quantitative calculation of the energy flow simulation model. Then, the performance pertinence is defined and calculated to describe the comprehensive influence of the design parameters on performance and to screen the critical parameters. Finally, the performance matching process is presented to support the performance matching. With a refrigerator as an example, 5 parameters were screened from 11 variable design parameters, and day power consumption decreased by 6.85%, which verifies the effectiveness of the method.

Suspension is the general name of the device that connects the conductive force between the car body and the wheels. Among them, operational stability and ride comfort are two contradictory requirements in actual driving. In the traditional vehicle suspension system, in order to maintain the ride comfort of the vehicle, the vibration energy caused by uneven road surface is usually dissipated by passive shock absorber in the form of heat. If this part of energy can be recovered in an effective way, the energy demand of the whole vehicle system can be reduced. Usually, the stiffness of semi-active suspension is constant, and the damping coefficient will change automatically with the change of driving conditions. Its advantages are simple structure, no need to consume automobile power, and the damping coefficient will change with the change of automobile driving conditions, which can effectively improve automobile riding comfort and handling stability. This paper expounds the problems encountered by traditional suspension, and analyzes the semi-automatic control strategy of regenerative suspension of new energy vehicles from the perspective of energy flow.

Hybrid propulsion dedicated to light duty vehicles is seen as an evolutionary change from internal combustion engine (ICE) to electric propulsion. Widespread direct replacement of convection ICEs in the current energy system is impossible because ICEs are vehicles’ main source of mechanical energy. The hybrid powertrain uses the advantages of electric propulsion with the ability to charge the traction battery or have the internal combustion engine assist the system. The article compares different types of hybrid drives (with a small share of plug-in hybrid propulsion) under typical urban driving conditions. Nine vehicles were tested, and the tests were conducted over several months in various cities in Poland. The terms of the research conducted were not under the requirements of the driving test. However, they are authoritative when using the vehicle in real traffic conditions. Such conditions take into account many aspects that are relevant to a road test. It was found that urban conditions are a very suitable environment for hybrid propulsion systems, as they cover more than 50% of the distance in electric mode, regardless of the initial battery charge, in most cases.

In this study, a new method for manipulating energy flow in a 3D vector field is proposed. In this method, an azimuthally-polarized beam with a noncanonical vortex, the X-type vortex, is focused in a high-numerical aperture system. It is found that, instead of the invariance of the energy flow which is characteristic of the traditional vortex (i.e., canonical vortex), both the longitudinal and the transverse energy flows in virtue of the X-type vortex rotate around the beam center as the beam propagates, and this rotational behavior (including the maxima location and the rotational angle) can be adjusted by the anisotropic parameter and the order the X-type vortex. Through defining a complex transverse Poynting field and applying the equivalence principle, the transverse energy flow and its topological reactions are discussed in the focal plane. Our result shows that, by changing the anisotropic parameter of the X-type vortex, rich topological reactions will occur, resulting in various distribution patterns of the energy flow, such as multi vortex-type singularities around the beam center. Our research demonstrates newly-observed features of the X-type vortex and also provides a simple method to manipulate energy flows both along longitudinal and transverse directions, which will be useful in optical manipulations.

In recent years, integrated pond aquaculture under controlled management has been crucial in improving the supply of aquatic products and ensuring food security. This study constructed two trophic models of integrated pond aquaculture ecosystems of Portunus trituberculatus–Penaeus japonicus (PP) and P. trituberculatus–P. japonicus–Sinonovacula constricta (PPS) using Ecopath with Ecosim software. The energy flows, ecosystem properties, and carrying capacities of the two ecosystems were analyzed and evaluated. The results showed that the ecotrophic efficiency values in the PP and PPS ecosystems were 0.962 and 0.954 for P. trituberculatus and P. japonicus and 0.952 for S. constricta. The effective trophic levels of P. trituberculatus and P. japonicus were 2.065 and 2.027 in the PP system, and those of P. trituberculatus, P. japonicus, and S. constricta were 2.057, 2.018, and 2.010 in the PPS system. The primary productivities of the PP and PPS ecosystems were 2623.79 and 2781.48 g/m2/240 days, with 2.13 and 37.83% of the energy flowing to trophic level II and 97.87 and 62.17% flowing to the detritus, respectively. The total energy of the detritus group was 2900.89 and 2372.98 g/m2/240 days, with 931.02 and 1505.35 g/m2/240 days flowing to trophic level II, respectively. The total primary production/total respiration ratio of the PPS ecosystem (1.632) was lower than that of the PP ecosystem (4.824), indicating that the former had a greater degree of exploitation. At the current feeding level, the carrying capacities of P. trituberculatus and P. japonicus were 65.15 and 47.62 g/m2 in the PP ecosystem, and those of P. trituberculatus, P. japonicus, and S. constricta were 64.96, 48.06, and 100.79 g/m2 in the PPS ecosystem, respectively. At adequate feeding levels, the carrying capacities of P. trituberculatus and P. japonicus were 83.76 and 48.52 g/m2 in the PP ecosystem and 81.82 and 53.44 g/m2 in the PPS ecosystem. The ecotrophic efficiency values and energy flow parameters of the two integrated pond aquaculture ecosystems indicated that S. constricta was a suitable collocation culture species for P. trituberculatus and P. japonicus, and there is room for further improvement in yields of this integrated aquaculture ecosystem.

The coordinated operation and comprehensive utilization of multi-energy sources require systematic research. A multi-energy microgrid (MEMG) is a coupling system with multiple inputs and outputs. In this paper, a system model based on unified energy flows is proposed to describe the static relationship, and an analogue energy storage model is proposed to represent the time-dependency characteristics of energy transfer processes. Then, the optimal dispatching model of an MEMG is established as a mixed-integer linear programming (MILP) problem using piecewise linear approximation and convex relaxation. Finally, the system model and optimal dispatching method are validated in an MEMG, including district electricity, natural gas and heat supply, and renewable generation. The proposed model and method provide an effective way for the energy flow analysis and optimization of MEMGs.

Forging production is widely used in aerospace, automobile, shipbuilding and other industries because of its high mechanical properties. Due to the high energy consumption and high pollution in steel and iron enterprises, with the promotion of green manufacturing and energy saving and emission reduction, more and more attention has been paid to the study of energy conservation problem. In this paper, combined with the process of forging production, the material flow of steel, fuel and other related accessories in the production process is studied and analyzed. Based on the material flow model, the energy flow direction of the forging process is qualitatively determined with the material as the carrier, and the energy flow model of the whole forging production process is carried out.

This study evaluated the photosynthetic efficiency in Rhizophora mangle plants in two mangrove forests, the highest salinity (HS) area, and the lower salinity (LS) area. The CO2 assimilation rate (PN), stomatal conductance, leaf transpiration, intrinsic water-use efficiency, and chlorophyll a fluorescence L-band, IP-phase, and performance index were higher in the LS area. The instantaneous water-use efficiency, initial fluorescence, maximum fluorescence, and J-step were higher in the HS area. The plants growing in the HS area exhibited greater efficiency in electron transfer between the oxygen-evolving complex and the acceptor side of the PSII. The plants growing in the LS area exhibited greater efficiency of the reduction of the final acceptors of the PSI, an important strategy to the stress conditions. The results show that a greater variation in salinity in the LS area had the effect on PN and long-term changes in the rainfall regime may alter the vegetation community of mangrove forests.

The archetypal foraging behaviour of tropical seabirds is generally accepted to differ from that of their temperate and polar breeding counterparts, with the former exhibiting less predictable foraging behaviour associated with the less predictable prey of the tropical marine environment. Similarly, temperate and polar species have predictable, annual breeding seasons, enabling them to profit during periods of the year when prey availability is highest, while tropical seabird species exhibit considerable variability in their breeding strategies. Until now, the reasons for such variation in breeding strategies between tropical seabirds are yet to be investigated. We hypothesise that while some tropical species breed asynchronously in response to unpredictable fluctuations in prey availability, others adopt a seasonal breeding strategy for the same reasons that temperate and polar species do. Consequently, the predictability of seabird foraging behaviour in the tropics may be related to breeding strategy, with populations that breed seasonally exhibiting more predictable foraging behaviour than those that breed aseasonally. To test these predictions, we used GPS tracking to examine the foraging behaviour of two closely related tropical seabird species that colonise the same island yet exhibit markedly different breeding strategies: the asynchronously breeding brown booby Sula leucogaster and the seasonal breeding masked booby Sula dactylatra. We obtained tracks for 251 birds over five years. We found that brown boobies forage less predictably than masked boobies, indicated by larger core foraging areas, lower levels of foraging area overlap between individuals and exhibit more variability between breeding periods. Our results challenge the view that the foraging behaviour of tropical seabirds is always less predictable than that of seabirds breeding in temperate and polar regions and highlight the considerable variability in the breeding and foraging strategies adopted by tropical seabirds which demand further exploration.

As the energy infrastructure of smart cities, smart grid upgrades traditional power grid systems with state-of-the-art information and communication technologies. In particular, as the full deployment of the Internet of Things in the power grid (a.k.a. power Internet of Things or PIoT), the newly introduced information flow together with inherent energy flow makes it more efficient for power generation, transmission, distribution, and consumption. To further exploit the precious energy and the latest 5G technologies, this article boosts to add a value flow in the smart grid, mainly including the value created by innovative services and market mechanisms and the value added by the information flow. Specifically, by integrating PIoT with cyber-physical systems, this article sketches a conceptual framework of the cyber-physical power system (CPPS). The CPPS carries out holistic perception and ubiquitous connection of distributed energy sources and electrical facilities and builds up a smarter power grid with global information interaction, intelligent decision-making, and real-time agile control. Finally, for illustration purposes, we conduct a case study regarding an intelligent home management system.

During human walking, mechanical energy transfers between segments via joints. Joint mechanics of the human body are coordinated with each other to adapt to speed change. The aim of this study is to analyze the functional behaviors of major joints during walking, and how joints and segments alter walking speed during different periods (collision, rebound, preload, and push-off) of stance phase. In this study, gait experiment was performed with three different self-selected speeds. Mechanical works of joints and segments were determined with collected data. Joint function indices were calculated based on net joint work. The results show that the primary functional behaviors of joints would not change with altering walking speed, but the function indices might be changed slightly (e.g., strut functions decrease with increasing walking speed). Waist acts as strut during stance phase and contributes to keep stability during collision when walking faster. Knee of stance leg does not contribute to altering walking speed. Hip and ankle absorb more mechanical energy to buffer the strike during collision with increasing walking speed. What is more, hip and ankle generate more energy during push-off with greater motion to push distal segments forward with increasing walking speed. Ankle also produces more mechanical energy during push-off to compensate the increased heel-strike collision of contralateral leg during faster walking. Thus, human may utilize the cooperation of hip and ankle during collision and push-off to alter walking speed. These findings indicate that speed change in walking leads to fundamental changes to joint mechanics.