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Arid areas account for more than 20% of Earth's surface. Many of these arid areas suffer from harsh climates where energy consumption is high and production coexists with high hydrological stresses. In such areas, the production of water is directly linked to the production of electricity, bringing the Energy–Water nexus to a higher level [Heggy et al., Sustainable Energy-Water-Environment Nexus in Deserts (Springer, 2022)]. Under the current energy transition from a fossil-based economy to a renewable energy-based system, arid areas are seen as potential reservoirs for electricity production due to their high solar potential, thereby helping to achieve global decarbonation targets. This energy production transition will strongly affect the Energy–Water nexus as it will contribute to the decoupling of electricity from water production. The International Conference on Sustainable Energy–Water–Environment Nexus 2019 (ICSEWEN19) conference was the first to address the Sustainable Energy–Water Nexus in Deserts, bridging the gap between research and industry and highlighting the research capabilities relevant to Qatar, the region, and internationally. The Invited Papers from the International Conference on Sustainability, Energy, Water, and Environment Nexus in Desert Climates Special Collection in Journal of Renewable and Sustainable Energy presents articles covering the main elements of the conference with respect to solar photovoltaic implementation in desert environments as a key element to succeed in this global energy transition. [ABSTRACT FROM AUTHOR]

In this paper, a wideband metasurface-loaded (MTS-L) rectenna system is proposed to capture electromagnetic (EM) energy at arbitrary azimuth angles. The radiation patterns of different modes in the original MTS configuration are analyzed using the characteristic mode theory, and potential modes with omnidirectional radiation are screened out. By the arrangement of patches, the roundness performance of the radiation pattern can be ameliorated, and the omnidirectional characteristic is obtained over a wide frequency band. Subsequently, the surface current density of the selected mode is carefully and artificially designed to facilitate probe excitation as well as refrain from introducing complex power-combining networks. A wideband rectifier circuit is designed as the load of the proposed antenna. Eventually, measured results show that it operates from 4.6 to 9.6 GHz with a fractional bandwidth of 70.4%, and the peak system efficiency is 52.2%. The proposed system demonstrates excellent potential for wireless power transmission and EM energy harvesting in indoor environments. [ABSTRACT FROM AUTHOR]

To enhance the utilization of clean energy sources, such as wind power and photovoltaic within virtual power plants, and mitigate carbon emissions, this paper proposes a virtual power plant participation in the electricity carbon joint market optimization operation model based on ensemble empirical mode decomposition–improved bat algorithm (IBA)–Markov chain new energy output prediction. First, complementary set empirical mode decomposition is performed on historical data to construct a Markov chain based wind power and photovoltaic prediction model optimized by IBA. Second, this prediction model is used to predict the daily generation power of wind power and photovoltaic power. Finally, with the optimization goals of maximizing the benefits and minimizing the carbon costs of virtual power plants, a virtual power plant system participating in the electricity carbon joint market model based on wind power and photovoltaic output prediction results is constructed. At the same time, demand response factors are introduced and solved using the NSGA-II algorithm. Taking a certain park as an example for simulation analysis, the research results show that the combined effect of carbon market and demand response can achieve 99.82% of new energy consumption in virtual power plants without significantly reducing profits, basically achieving complete new energy consumption, demonstrating the effectiveness of the proposed model in this paper. [ABSTRACT FROM AUTHOR]

This paper proposes the first linear scaling implementation for the domain decomposition approach of the polarizable continuum model (ddPCM) for the computation of the solvation energy and forces. The ddPCM-equation consists of a (non-local) integral equation on the van der Waals or solvent accessible surface of the solute's cavity resulting in a dense solution matrix, and, in turn, one matrix–vector multiplication has a quadratic arithmetic complexity with respect to the number of atoms of the solute molecule. The use of spherical harmonics as basis functions makes it natural to employ the fast multipole method (FMM) in order to provide an asymptotically linear scaling method. In this paper, we employ the FMM in a non-uniform manner with a clusterization based on a recursive inertial bisection. We present some numerical tests illustrating the accuracy and scaling of our implementation. [ABSTRACT FROM AUTHOR]

In this paper, we use the previously introduced Canonical Polyadic (CP)-Multiple Shift Block Inverse Iteration (MSBII) eigensolver [S. D. Kallullathil and T. Carrington, J. Chem. Phys. 155, 234105 (2021)] in conjunction with a contraction tree to compute vibrational spectra. The CP-MSBII eigensolver uses the CP format. The memory cost scales linearly with the number of coordinates. A tensor in CP format represents a wavefunction constrained to be a sum of products (SOP). An SOP wavefunction can be made more accurate by increasing the number of terms, the rank. When the required rank is large, the runtime of a calculation in CP format is long, although the memory cost is small. To make the method more efficient, we break the full problem into pieces using a contraction tree. The required rank for each of the sub-problems is small. To demonstrate the effectiveness of the ideas, we computed vibrational energy levels of acetonitrile (12-D) and ethylene oxide (15-D). [ABSTRACT FROM AUTHOR]

In the context of power systems with a high proportion of renewable energy, energy storage plays a significant role in facilitating the consumption of renewable energy and ensuring the operational safety of power systems. However, the current power spot market's predominant power bidding model does not fully consider the physical and cost-operational characteristics of energy storage, which is not conducive to further incentivizing investment and construction of energy storage, and may indirectly affect the flexibility of energy storage in peak shaving and valley filling. This paper summarizes the key issues that need to be addressed for energy storage to participate in the spot market from two aspects: the power bidding model does not meet the requirements of the physical and cost-operational characteristics of energy storage, and the real-time market under this model cannot achieve optimal allocation of energy storage. Considering the energy constraints and cost characteristics of energy storage, a charge and discharge bidding model is proposed, which is based on the stored energy value of energy storage and is in line with the physical and cost-operational characteristics and real-time optimization needs of energy storage. Subsequently, a market clearing model for energy storage participation in the spot market under the state of energy bidding method is constructed, and based on the IEEE 39-bus test case, a comparative analysis of the nodal electricity prices, energy storage revenue, and total system costs under the proposed market participation model and the traditional power bidding model is conducted. Simulation results show that the proposed energy storage participation model in the spot market can better utilize the value of energy storage in peak shaving and valley filling compared to the conventional power bidding model, reducing the extreme electricity prices by up to 10%, increasing single cycle revenue of energy storage by 46%, and reducing the total operating costs of the system in scenarios with significant deviations in system load in the day-ahead and real-time markets. [ABSTRACT FROM AUTHOR]

The efficient utilization of renewable energy is a key technology area of high domestic and international concern, and the research and development of DC–DC photovoltaic converters with high conversion efficiency is of great significance for improving performance and reducing the cost of solar power generation systems. In order to improve the conversion efficiency of solar energy, this paper proposes the design of a high-efficiency photovoltaic DC–DC converter with a non-isolated DC–DC converter as the object of the study. Solar power conversion is accomplished by designing a simple and reliable snubber circuit and a triode auxiliary circuit and tracking the maximum power point by combining the perturbation observation method with variable step size. The snubber circuit can effectively suppress the problems of pulse spikes and oscillations, and the triode auxiliary circuit prevents the reverse current and improves the switching speed, which reduces the switching loss and combines with the perturbation observation method with variable step size for fast and stable tracking of the maximum power point. In order to verify the feasibility of the converter, a 600 W prototype is designed. The experimental results show that using the snubber circuit reduces the pulse spike by 4.2 V and the overshoot is reduced by 4.3%. The maximum conversion efficiency is increased by 0.88% with the use of the transistor-assisted circuit, and the tracking efficiency of the MPPT is still stable under cloudy conditions. The maximum conversion efficiency of the prototype is finally measured to be up to 98.12%. [ABSTRACT FROM AUTHOR]

China, a country with a long-standing agricultural legacy, is increasingly prioritizing the reduction of CO2 emissions from its agricultural sector. Initially, the carbon emission sources within the agricultural sector are classified into two categories: direct and indirect emissions. Using this classification, the study calculates the generalized agricultural carbon emissions (GACEs) of 30 provinces in China between 2011 and 2020. To further understand the factors influencing GACEs, the paper employs the logarithmic mean Divisia index method and Tapio decoupling index to analyze seven key factors. These factors include carbon emission intensity, energy consumption of generalized agriculture, and economic benefit level of energy consumption. By comparing the impact and changes of GACEs during the 12th and 13th five-year plan periods, the study reveals valuable insights. The findings suggest that carbon emission intensity plays a crucial role in suppressing GACEs, while the level of economic development acts as a catalyst for their increase. By effectively managing these influencing factors, the paper proposes that the increase in GACEs can be effectively suppressed, and the achievement of agricultural CO2 reduction goals can be expedited. [ABSTRACT FROM AUTHOR]

Thermophotovoltaic (TPV) devices, which can break the Shockley–Queisser limit (33.7%) and enhance the thermal energy utilization efficiency, have garnered increasing attention in recent decades. Structuring the emitter surface has been demonstrated to be powerful for tailoring thermal emission to enhance the power density and system efficiency of a TPV system. However, the design and optimization of the broad parameters of the surface nanostructures manually remain to be thorny issues. In this paper, the Bayesian algorithm under the framework of material informatics was coupled with a rigorous coupled wave analysis to optimize the geometry of the infrared grating nanostructure to achieve wavelength-selective emission to boost the TPV performance. It is demonstrated that only less than 0.173% of the total candidate structures were calculated to find out the optimal structure with high spectral emittance in the range of 0.3–1.708 μm, and the power density and system efficiency of the TPV system were enhanced to 4.20 W/cm2 and 35.37%, respectively. The present machine-learning-based optimization of a multi-parameter nanostructure can improve the performance of the TPV system significantly and can be extended to other physical fields in a feasible manner. [ABSTRACT FROM AUTHOR]

Present paper numerically investigates the effect of injection strategy and start of injection (SOI) timing on in-cylinder flow, air–fuel mixing, fuel distribution near spark plug, engine performance, and exhaust emissions for highly stratified methanol-fueled, multi-injection, direct injection spark ignition engine having high compression ratio. SOI is kept constant at −23° crank angle (CA) after top dead center (ATDC) with a spark timing (ST) of −2° crank angle (CA) ATDC. Mass of fuel is divided into pilot and main injection ports having pilot to main fuel injection mass ratio of 1:1, 1:2, and 1:3 at 0° and 2° dwell times between main and pilot injections. As the quantity of fuel in main injection increases, pressure rise rate increases, which results in higher in-cylinder pressure and higher rate of burning that gives higher apparent heat release. Due to higher peak pressure rise rate and faster burning in the case of 2° crank angle (CA) dwell time, shorter combustion duration is achieved compared to 0° crank angle (CA) dwell time. In the case of multi-injection, faster burning rate enhanced in-cylinder temperature; therefore, nitrogen oxides (NOx) emissions are higher. Pilot to main fuel mass ratio of 1:3 has resulted highest indicated thermal efficiency, lowest specific fuel consumption, lowest soot, and carbon monoxide (CO) emissions. [ABSTRACT FROM AUTHOR]

Railway traffic plays a pivotal role within the current transportation system, with ensuring its safety being of paramount importance. Real-time monitoring of train track health through sensor technology has emerged as a significant approach for achieving this objective. However, a persistent challenge lies in providing cost-effective and stable power to sensors in remote areas. This paper proposes the utilization of a novel piezoelectric stack energy harvester in railway systems to address this issue. The substantial and consistent vibration energy produced by railway operations makes it an ideal source for energy harvesting, unaffected by environmental conditions. Through simulation analysis and experimental verification, this study explores the impact of load size, load frequency, and external resistance on the energy harvesting efficiency of the proposed piezoelectric stack energy harvester. The results indicate that the output power of the energy harvester increases with the load size. Furthermore, the frequency significantly influences the energy capture efficiency when below 8 Hz, with minimal impact on frequencies above 8 Hz. Interestingly, the load dramatically affects the energy capture efficiency, even at higher frequencies. With the external resistance set to 250 kΩ, the harvester achieves a maximum output power of 42.76 mW. [ABSTRACT FROM AUTHOR]

Time-varying metasurfaces offer an efficient means of controlling nonlinear harmonics by manipulating component geometries and modulating signals. This ability renders them valuable across various fields, such as wireless communication, radar sensing, and biological monitoring. However, most of the energy in time-varying metasurfaces is concentrated in the fundamental wave, as well as scattered at various harmonic orders, which reduces the energy efficiency at the desired harmonic. Existing approaches have employed time-varying coding digital metasurfaces to achieve efficient harmonic conversion but are primarily designed for reflection. Reflection-based designs require a feed source to excite the metasurface, which can cause certain shielding effects and limit their application in specific scenarios. Thus, designing transmissive time-varying coding digital metasurfaces for efficient harmonic conversion is currently an urgent problem that needs to be addressed. To solve this problem, this paper develops a time-varying coding digital double-layered Huygens' metasurface, which achieves efficient conversion of the desired transmitted harmonics. The unit structure of the metasurface consists of a pair of reverse-symmetric split rings located on the upper and lower sides of a dielectric substrate, enabling nearly non-reflective Huygens' resonance. Based on a continuous periodic phase modulation strategy, we achieved efficient conversion of transmitted harmonics by loading a time-varying voltage (phase) modulation signal with a 5-bit resolution bit width onto the designed double-layered Huygens' metasurface. This study presents a solution for designing a transmissive time-varying coding digital metasurface to achieve efficient conversion of harmonics, thereby enhancing the application capabilities of time-varying coding digital metasurfaces. [ABSTRACT FROM AUTHOR]

In this paper, we consider the convergence rates for the 2D stationary and non-stationary Navier–Stokes Equations over highly oscillating periodic bumpy John domains with C2 regularity in some neighborhood of the boundary point (0,0). For the stationary case, using the variational equation satisfied by the solution and the correctors for the bumpy John domains obtained by Higaki and Zhuge [Arch. Ration. Mech. Anal. 247(4), 66 (2023)] after correcting the values on the inflow/outflow boundaries ({0} ∪ {1}) × (0, 1), we can obtain an O(ɛ3/2) approximation in L2 for the velocity and an O(ɛ3/2) convergence rates in L2 approximated by the so called Navier's wall laws, which generalized the results obtained by Jäger and Mikelić [J. Differ. Equations 170(1), 96–122 (2001)]. Moreover, for the non-stationary case, using the energy method, we can obtain an O(ɛ3/2 + exp(−Ct)) convergence rate for the velocity in L x 2 . [ABSTRACT FROM AUTHOR]

The prevention and treatment of organic pollutants in wastewater have attracted extensive attention because they threaten ecological balance and human health. Traditional wastewater treatment technologies, such as physical, chemical, biological methods, etc., are still limiting and challenging due to some factors, such as high energy consumption, chemical agents, low efficiency, and secondary pollution. At present, gliding arc plasma, based on equilibrium/non-equilibrium in plasma temperature, demonstrates itself to be one of the most promising technologies for the degradation of refractory organics with its fast degradation rates, no secondary contamination, high efficiency, and so on. The theoretical mechanisms and typical applications of gliding arc plasma degradation of wastewater are introduced in detail in this paper. The physical and chemical characteristics of gliding arc plasma and the role of the reactive species in the plasma are reviewed. [ABSTRACT FROM AUTHOR]

In previous research on energy harvesting from vortex-induced vibrations (VIVs), the cross section of the structure commonly utilizes basic geometric shapes like circular, ellipse, square, and semicircle. Nevertheless, exploring optimized shapes for energy harvesting from VIV remains an understudied area. To address this gap, this paper employs adjoint-based unsteady shape optimization to increase the efficiency of energy harvesting from VIV of a circular cylinder at low Reynolds numbers. The goal of the optimization is to maximize the plunge-damping derivative of a single-degree-of-freedom transversely vibrating cylinder, which represents the rate of energy injected into the structure by the flow. To facilitate this process, an efficient method to evaluate the gradient of the objective function with respect to shape parameters is provided via the proposed unsteady discrete adjoint method. Results show that, through optimization, the low-pressure region behind the cylinder is significantly enlarged and the separation points move forward, resulting in the faster development of separation vortex and reduced stability of the fluid–structure coupling system. As a consequence, the intensity of VIV as well as the corresponding power generation efficiency is remarkably enhanced, accompanied by a notable expansion in the energy harvesting region. [ABSTRACT FROM AUTHOR]

Salinity gradient power generation based on nanochannels has drawn much attention for its green and sustainable advantages. However, previous studies have tended to focus on regularly shaped nanochannels, while rough and irregular surfaces are naturally formed during the preparation of nanochannels (similar to sinusoidal nanochannels). In this paper, a model of salinity gradient energy conversion in sinusoidal nanochannels is established. The impacts of the geometrical parameter dimensions of the sinusoidal channel (including initial phase, channel length, average radius, amplitude, and angular frequency) on the power generation performance under different salinity gradients are systematically investigated. The results show that the sinusoidal nanochannel has better salinity gradient power generation performance than cylindrical nanochannel. It obtains the best power generation performance when the initial phase is zero. Besides, increasing the nanochannel length facilitates ion selectivity and energy conversion efficiency. At high concentration difference, decreasing the average radius or increasing the amplitude help increase the maximum output power and enhance the energy conversion efficiency. The maximum output power of about 1.27 pW and energy conversion efficiency of about 32.8% were obtained by optimizing the sinusoidal channel amplitudes. It is also found that increasing the angular frequency is favorable to improving energy conversion performance at the high concentration difference. These results provide helpful information for designing and optimizing salinity gradient energy conversion systems. [ABSTRACT FROM AUTHOR]

Hydropower station tailwater channel is often prone to elevated water levels and insufficient energy consumption, which leads to the influence of the output of the unit. To study the intrinsic connection between the water flow state and elevated water level in the tailwater channel, this paper investigates the water flow characteristics inside the tailwater channel of the Mupo Hydropower Station under different heads and verifies the accuracy of numerical calculations by constructing a physical model test platform. The results show that the maximum velocity at the bottom of the fluid domain near the anti-slope section of the tailwater channel decreases with the increase of head, while the velocity at the top of the fluid domain near the anti-slope section of the tailwater channel does not change much with the increase of head; a large vortex is formed in the middle of the upper part of the fluid domain in the anti-slope section of the tailwater channel; and the lower the head, the more obvious the vortex is. The results provide guidance for the design of tailwater channels at hydropower stations. [ABSTRACT FROM AUTHOR]

After the service provider temporarily selects the required edge nodes based on social and storage capabilities, application execution causes the edge nodes to cache part of the application data. Therefore, offloading part of the application computing tasks to the selected edge nodes can effectively improve application execution performance. However, in cases where the resources of user's IoT devices are insufficient, tasks can be further offloaded to traditional edge servers or even to the cloud to maximize application execution efficiency. In this paper, the entire uninstall utility is modeled as a weighted sum of task completion time and energy consumption. Under the premise of considering users' preferences for completion time and energy consumption, a game-based uninstallation algorithm is proposed. The algorithm performs uninstallation by optimizing the uninstallation decision. Based on user preferences, the total system overhead is relatively small. The subsequent simulation experiments show that the algorithm can reduce system overhead on the basis of satisfying user preferences and has relatively good adaptability. [ABSTRACT FROM AUTHOR]

The cavity-assisted scramjet has been proven to be the most promising propulsion system for air-breathing hypersonic vehicles. In this paper, numerical simulations of a Mach 8 axisymmetric scramjet combustor are conducted and validated to investigate the effect of the cavity. The results indicate that the combustion state undergoes significant changes as the combustion heat release increases. Detailed analysis reveals that the role of the cavity in flame stabilization and combustion enhancement also changes with combustion heat release. Under weak heat release conditions, the high-speed environment results in reduced combustion efficiency, and the primary role of the cavity is to stabilize the flame. Increasing the cavity size does not yield significant gains but could bring redundant mass. As heat release intensifies, the combustion enhancement effect of the cavity becomes more prominent. The presence of the cavity dramatically improves fuel combustion efficiency. The distribution of supersonic and subsonic combustion modes, as well as that of premixed and diffusion combustion modes, is also affected by cavity size and combustion heat release. In the engineering development of scramjets, it is suggested that the design of the cavity flameholder should involve careful consideration of combustion heat release. [ABSTRACT FROM AUTHOR]

With the wide application of high proportion of distributed clean energy in regional microgrids, the issue of maximizing the utilization of renewable energy among multi-microgrids has become a research hotspot. Based on the proposed multi-microgrids' energy collaborative optimization and complementation model, a multi-microgrids' energy real-time optimization management and dispatch strategy is proposed that fully considers the real-time complementarity of renewable energy between multi-microgrids and achieves the best coordinated dispatch of energy. Two typical scenarios were set up in the IEEE 33-bus network model for verification, and the synergistic effects of different schemes were compared and set up. The data obtained demonstrate that the dispatch and management strategy proposed in this paper can achieve the maximum integration of renewable energy and the lowest operating cost among multi-microgrids, and it also validates the real-time, feasibility, and effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

Micro energy grids (MEGs) play a vital role in realizing carbon neutrality and efficient utilization of renewable energy resources. This research focuses on optimizing the synergy of MEG interconnections. Given the diverse development paths of different operating entities within the system, information barriers emerge among MEGs, creating great difficulties for the collaborative system management. In response, this paper proposes a decentralized coordinated dispatch model targeting multiple stakeholders within the system. This model accounts for energy interactions between MEGs and the inherent uncertainty associated with renewable energy sources. Specifically, stochastic optimization approach was applied to characterize the uncertainty of renewable energy output by generating stochastic scenarios. Furthermore, it incorporates the analytical target cascading (ATC) method to decouple objective functions and constraints, creating autonomous scheduling sub-models for individual MEGs. This decentralized approach ensures independent modeling and coordinated problem-solving. Simulations verify that (1) the ATC-based inter-MEG energy interaction strategy effectively achieves decentralized coordinated scheduling of multiple MEGs and (2) the decentralized coordinated scheduling solution closely approximates the global optimum while considering the interest of various system entities. [ABSTRACT FROM AUTHOR]

Non-intrusive load monitoring (NILM) is a technique that efficiently monitors appliances' operational status and energy consumption by utilizing voltage and current data, without intrusive measurements. In NILM, designing efficient classification models and building distinctive load features are crucial. However, due to its continuously variable load characteristics, multi-state load identification remains the most challenging problem in NILM. In this paper, we improve the encoding of the color V–I trajectory by incorporating instantaneous power, thereby enhancing the uniqueness of V–I trajectory features. Furthermore, we investigate a NILM method based on deep learning methods and propose a densely connected convolutional network with squeeze-and-excitation network (SE-DenseNet) architecture to solve the multi-state load identification problem. Initially, the architecture leverages DenseNet's dense connectivity property to generate a multitude of feature maps from the V–I trajectory. Then, SENet's channel attention mechanism is employed to enhance the utilization of effective features, which is more effective for multi-state load identification. Experimental results on the NILM public datasets PLAID and WHITED show that the recognition accuracy of the proposed method reaches 98.60% and 98.88%, respectively, which outperforms most existing methods. [ABSTRACT FROM AUTHOR]

Aerodynamic performance of wind turbine governs the overall energy efficiency, which has been an ever-lasting research focus in the field of wind power technology. Due to the coupling effect among the highly complex environmental and structural uncertainties, the practical aerodynamic performance may not be reliably predicted. To aggravate, this performance declines with time in service. It is of great significance to efficiently and reliably assess the impact of uncertain factors and reduce these influences on wind turbine aerodynamic performance. This paper establishes an uncertainty analysis and robustness optimization model of wind turbine aerodynamic performance considering wind speed and pitch angle error uncertainties. An approach combined the no-instrusive probabilistic collocation method is used, and the blade element momentum theory is applied to quantify influences of variable uncertainties on NREL 5 MW wind turbine aerodynamic performance. The optimization target is to reduce the sensitivity of wind turbine aerodynamic performance to uncertainties, as well as maintain capture power. The results show that the wind turbine aerodynamic and mechanical performance will be greatly affected with uncertain factors. By optimizing and adjusting wind turbine rotor speed and blade pitch angle, the wind turbine rotor power and thrust load variation can be reduced to 9.14% and 9.36%, respectively, which indeed reduces the uncertainty effects. [ABSTRACT FROM AUTHOR]

Ocean waves contain a great deal of energy, and the collection and utilization of wave energy is of great significance for sustainable development. In this paper, a multi-direction piezoelectric and electromagnetic hybrid energy harvester (PEHEH) based on magnetic coupling is proposed that can collect low frequency vibration energy from multiple directions. The proposed PEHEH combines piezoelectricity and electromagnetism through magnetic coupling to collect energy in the same excitation. The mechanical model of the PEHEH is established, and finite element simulation software COMSOL and computational fluid dynamics are used to analyze and verify the feasibility and practicability of the PEHEH structure. An experimental platform is built to test the output performance of the PEHEH. The results show that the maximum energy generated by PEHEH is 19.4 mW when the magnetic distance is 16 mm and the excitation frequency is 9 Hz. The hybrid energy harvester can light 56 light emitting diodes, which verified the feasibility of practical application. Therefore, the proposed hybrid energy harvester can effectively collect low-frequency wave energy and has a broad application prospect as a power source for low-power electronic devices. [ABSTRACT FROM AUTHOR]

Understanding the flow of embodied energy between provinces in China and the factors affecting the network has an important impact on reducing energy consumption in each province and promoting balanced regional development. This paper uses the multi-regional input–output model to construct the interprovincial embodied energy flow network in China and defines the energy flow between provinces under the trade of products and services. Then, it uses the ecological network model to carry out the ascendency and network environ analysis of the interprovincial embodied energy flow network in China and uses the Quadratic Assignment Procedure regression model to calculate the impact of various factors on the flow network. The main research conclusions are as follows: (1) The embodied energy flow in the middle reaches of the Yangtze River and the Yellow River is relatively high. The embodied energy flow value in Ningxia and Qinghai is low. Zhejiang, Guangdong, and Jiangsu often have the highest embodied energy outflow value, while Inner Mongolia, Shanxi, and other provinces have higher inflows. (2) The center of gravity of through flow in the flow system is biased to Jiangsu, Guangdong, and other places; Gansu, Ningxia, Qinghai, and Hainan are at the edge of the system. (3) The differences in the economic development level, population size, and energy structure have a positive impact on the embodied energy flow network between provinces in China; the geographic distance will have a negative impact on the flow network. [ABSTRACT FROM AUTHOR]

The fluctuation of renewable energy resources and the uncertainty of demand-side loads affect the accuracy of the configuration of energy storage (ES) in microgrids. High peak-to-valley differences on the load side also affect the stable operation of the microgrid. To improve the accuracy of capacity configuration of ES and the stability of microgrids, this study proposes a capacity configuration optimization model of ES for the microgrid, considering source–load prediction uncertainty and demand response (DR). First, a microgrid, including electric vehicles, is constructed. Second, the uncertainty of renewable energy resources and electric demand is handled by Monte Carlo scenario generation techniques and K-means-based scenario reduction techniques. Then, a DR model combining price-based demand response and incentive-based demand response is constructed to achieve a better match between electricity demand and supply. Finally, the results of the ES capacity configuration are determined with the objective of minimizing the total daily cost of the microgrid. The simulation results show that the optimal configuration of ES capacity and DR promotes renewable energy consumption and achieves peak shaving and valley filling, which reduces the total daily cost of the microgrid by 22%. Meanwhile, the DR model proposed in this paper has the best optimization results compared with a single type of the DR model. It is verified through comparative analysis that under a certain proportion of flexible loads, the total daily cost of the microgrid is the lowest when the time-shiftable loads and the curtailable loads are both 10%. [ABSTRACT FROM AUTHOR]

With the rapid growth of big data information and the continuous iteration progress of CPU architecture, the implementation of a new memory-based cache architecture is urgent and challenging. In the paper, a CPU cache architecture system based on MRAM is built. Firstly, the performance of SRAM, STT-MRAM and SOT-MRAM as caches from 8 kb to 32 Mb is evaluated. Secondly, by summarizing the performance of SRAM and MRAM in different cache levels, a new quad-core CPU cache architecture design scheme with SOT-MRAM as the first level of cache and STT-MRAM as the second level of cache is determined. Thirdly, the built cache system is simulated. A non-inclusive strategy is proposed to replace the inclusive strategy in order to solve the problem of high dynamic energy of STT-MRAM at the second level. The idea of having a quad-core CPU dynamically share the second-level cache is proposed in the paper. Finally, the caching system in the paper is compared with the other previous works, showing up to 60.78% energy consumption advantage and 33.22% leakage power advantage. The proposed MRAM-based CPU cache system and the corresponding cache strategy have potential application with the benefits of low power and less area. [ABSTRACT FROM AUTHOR]

This paper concerns virus droplet simulations in a typical cruiser's cabin. Effects of ventilation rates and positions of the coughing person were investigated. The study also emphasizes the importance of including evaporation models to simulate the process accurately. A higher ventilation rate is not always the best strategy to avoid the spread of airborne diseases, as saliva droplets can spread further at high ventilation rates. Regardless of the ventilation strategy, they evaporate faster than the room's air renewal. One should aim for minimum droplet spreading inside the cabin and different ventilation strategies for occupied cabins. The authors propose using ventilation systems at medium flow rates of around 120 m3/h or three air changes per hour when a cabin is occupied. This value is also close to the recommended value of 108 m3/h from the latest standard by the American Society of Heating, Refrigerating and Air-Conditioning Engineers. The suggested value minimizes droplet spreading while maintaining good ventilation, comfort, and energy consumption. [ABSTRACT FROM AUTHOR]

In order to control the collision of long-span cable-stayed bridges with floating systems caused by large longitudinal displacement of beam ends under earthquake action, based on the engineering background of a long-span dual-purpose double-tower cable-stayed bridge, the collision problem of the main approach bridge under earthquake action is proposed. Two kinds of intelligent fuzzy control strategies based on different membership functions are presented, using MR Damper as a control device and modeled by SIMULINK. In this paper, the damping control effect of the proposed fuzzy control strategy on the collision problem of the main approach bridge of the cable-stayed bridge is studied. The results show that changing the range of the membership function will change the size of the control current, and the longitudinal displacement and acceleration of the structure will decrease with the increase in the control current. However, when the control current is too large, the acceleration response will be amplified and oscillated. Both fuzzy controls can reduce collision times, and the peak value of collision force between the main approach bridges and the energy consumption of the MR damper are roughly similar. Based on the control effect of longitudinal displacement response, acceleration response, and collision force response of the main approach bridge and the energy consumption of the damper, fuzzy control A is better than fuzzy control B. [ABSTRACT FROM AUTHOR]

Both thermoelectric conversion materials and infrared (IR) radiation materials enjoy broad applicability in energy utilization and aerospace. Therefore, it is essential to study the relationship between the physical properties of these two materials. This paper investigates the connection between the thermoelectric properties and the IR radiation properties using a SrTiO3-based thermoelectric material. As a result, we have demonstrated the correlation between a material's Seebeck coefficient and IR emissivity using experimental data and theoretical calculations. With increasing Seebeck coefficient, the IR emissivity increases. The material's IR emissivity falls as its electrical conductivity rises, and vice versa. When the material's thermal gradient is low, its IR emissivity influences its IR radiation energy. As the thermal gradient of the material increases, the IR radiation energy incident on the material surface is mainly influenced by the material's thermal conductivity. This work provides a fresh perspective on modulating the IR radiation and thermoelectric properties using the connection found in this study. The results provide theoretical guidance for studies at the intersection of thermoelectric and IR materials. [ABSTRACT FROM AUTHOR]

Effervescent atomization is widely used in industrial, agricultural, and national defense fields because of its low energy consumption. Quality improvement to spray has been pursued for decades as an important goal without increasing energy consumption. To investigate the relationship between the internal flow and spray characteristic, a swirl effervescent atomizer coupled with a wire mesh was designed in this paper. The effect of wire mesh on spray characteristics and internal flow with different structural parameters was investigated. The experimental results showed that the spray quality (small droplet diameter and stable atomization) was improved by installing a wire mesh in the mixing chamber. The droplet diameter decreased first and then increased with the increase in the effective porosity of the wire mesh, and Sauter mean diameter decreased from 23.1 to 20 μm. Moreover, this study adopts the simulation to explore the influence of bubble size on the spray droplet in the mixing chamber. The simulation results showed that as the effective porosity of the wire mesh increases, the proportion of small-scale bubbles (the bubble diameter Db ≤ 1 mm) increased from 11.3% to 83.37%, resulting in reduced spray droplet diameter. Notably, the number of small-scale bubbles increases first and then decreases, and the mean pressure drops decline. [ABSTRACT FROM AUTHOR]

Energy conversion efficiency and operation bandwidth are two main concerns in piezoelectric energy harvesting in low-frequency vibration environments. This paper presents a compact two-degree-of-freedom nonlinear piezoelectric energy harvester (2DOF NPEH) with a stopper. The proposed harvester consists of an elastic beam, a piezoelectric beam with tip mass, a pair of repulsive magnets, and a mechanical stopper. A bistable configuration is established through magnetic interaction. This study investigates the generating characteristics of the 2DOF NPEH under frequency-sweep excitation, utilizing a rigid stopper (RS) and different elastic stoppers (ESs). The experimental results indicate that the implementation of a mechanical stopper in a NPEH contributes to widening the operation bandwidth and enhancing the peak voltage. As the stiffness of the stopper increases, the bandwidth gradually shrinks while the peak voltage increases. The optimal energy conversion efficiency depends on the stiffness of the ES, and it occurs when the wire diameter of the spring is 1.2 mm. Compared with the 2DOF NPEH without a stopper, the utilization of a RS results in a 13.85-fold increase in the bandwidth of the generator at the first resonance. Moreover, the maximum absolute voltage is 12.82 times and 3.47 times the output voltage of the 2DOF NPEH at the first and second resonance, respectively. This work offers valuable insights into the design and optimization of piezoelectric energy harvesters in practical applications. [ABSTRACT FROM AUTHOR]

Silicon-on-insulator (SOI) devices have many advantages, such as high speed, low energy consumption, radiation-hard, and high integration. In this paper, the separation by implanted oxygen process under low-dose implantation conditions is studied by the two-step implantation method combined with the internal thermal oxidation process. The effects of different types of silicon wafers and different implantation doses on SOI surface defects, top Si thickness, buried oxide (BOX) layer thickness, BOX layer breakdown voltage, and top Si defect density were investigated. Ultra-thin SOI wafers are prepared by epitaxial silicon wafers and control the first implantation dose. The number of surface defects of SOI materials is less than 100 counts, the breakdown voltage of the BOX layer is about 7.8 MV/cm, and the top Si dislocation density is about 8 × 103 cm−2. [ABSTRACT FROM AUTHOR]

The computing industry is rapidly moving from a programming to a learning area, with the reign of the von Neumann architecture starting to fade, after many years of dominance. The new computing paradigms of non-von Neumann architectures have started leading to the development of emerging artificial neural network (ANN)-based analog electronic artificial intelligence (AI) chipsets with remarkable energy efficiency. However, the size and energy advantages of electronic processing elements are naturally counteracted by the speed and power limits of the electronic interconnects inside the circuits due to resistor-capacitor (RC) parasitic effects. Neuromorphic photonics has come forward as a new research field, which aims to transfer the well-known high-bandwidth and low-energy interconnect credentials of photonic circuitry in the area of neuromorphic platforms. The high potential of neuromorphic photonics and their well-established promise for fJ/Multiply-ACcumulate energy efficiencies at orders of magnitudes higher neuron densities require a number of breakthroughs along the entire technology stack, being confronted with a major advancement in the selection of the best-in-class photonic material platforms for weighting and activation functions and their transformation into co-integrated photonic computational engines. With this paper, we analyze the current status in neuromorphic computing and in available photonic integrated technologies and propose a novel three-dimensional computational unit which, with its compactness, ultrahigh efficiency, and lossless interconnectivity, is foreseen to allow scalable computation AI chipsets that outperform electronics in computational speed and energy efficiency to shape the future of neuromorphic computing. [ABSTRACT FROM AUTHOR]

Many fish propel themselves using wave-like lateral flexion of their body and tail in the water. The undulatory body is driven by the distributed muscles, and locomotion is achieved by internal muscular stimulation and the external action of the fluid. As one of the material properties, the stiffness of the body being propelled plays an important role in the deformation process, especially for the muscle power input and phase lag. In this paper, a three-dimensional self-propelled elongated body model is employed to numerically investigate the effects of stiffness on the propulsion performance, including the forward speed, energy consumption, and energy-utilization ratio. According to various deformation characteristics and energy-utilization ratios, three deformation modes corresponding to high, medium, and low stiffness are identified. Our results indicate that a deforming body with medium stiffness has the highest efficiency, and its corresponding deformation is closest to that of fish in nature. When the stiffness of the fish body is higher than the normal level, more muscle energy is needed to sustain the tail beating of the same amplitude. A lower level of stiffness produces a more obvious phase lag in the fish body, which might lead to slow control responses. We also show that the stiffness of the fish body affects the scaling relationship between the swimming speed and the tail beating velocity. The upper and lower limits of the scaling exponent correspond to high and low levels of stiffness, respectively, and are also affected by the wavelength of the muscle contraction. [ABSTRACT FROM AUTHOR]

In this paper, solar heat with mid- and high-temperature collected by molten salt parabolic trough solar field was integrated into the boiler sub-system of the double reheat coal-fired power generation system. Three typical integration modes were, respectively, evaluated by energy and exergy perspectives in terms of solar-generated electricity and solar energy conversion efficiency. Integration modes I–III utilized solar heat to preheat the inlet superheated steam, inlet reheated steam and inlet double reheated steam, respectively. Based on the case study through energy evaluation, it indicated that integrating solar energy with lower temperature led to higher solar-generated electricity, higher solar-to-solar heat efficiency, and higher solar-to-electricity efficiency. Integration mode I was unreasonably regarded superior to the other two, because the energy evaluation method ignored the quality of solar energy and mistakenly regarded the efficiency of solar heat to solar-generated electricity as the cycle efficiency. As an update, exergy evaluation takes both energy quantity and energy quality into consideration by regarding the efficiency of solar heat exergy to solar-generated electricity as the cycle exergy efficiency. It indicated that integration mode II was more recommended, with the highest solar-to-solar heat exergy efficiency and solar-to-electricity efficiency being 34.0% and 24.7%, respectively. The corresponding aperture area and solar-generated electricity are 5.7 × 105 m2 and 136.1 MW, respectively. [ABSTRACT FROM AUTHOR]

Coalescence-induced self-propelled droplet jumping has attracted extensive attention because of its huge potential for enhancing dropwise condensation heat transfer, anti-icing, and self-cleaning. Most previous studies focus on binary droplet jumping, with little research on the more complex and realistic multi-droplet jumping. As a result, the effect of the droplet arrangement on the multi-droplet jumping phenomenon remains unclear. In this paper, the self-propelled jumping of three droplets with different arrangements (two droplets are fixed, and the location of the third one is changed) is numerically simulated, and energy conversion efficiency is studied. Based on two different forming mechanisms, region I (the coalescence between the lateral droplets forms the central liquid bridge) and region II (the changed interface curvature of central droplets turns into the central liquid bridge under surface tension) are defined in three-droplet arrangements. The liquid bridges exhibit different dynamic behaviors in two particular regions, even the jumping velocity is determined by the moving synchronicity of liquid bridges in each region. The critical distribution angle that leads to the overall nonmonotonic change of jumping velocities ranges between 110° and 120° (0.02 ≤ Oh ≤ 0.16). Compared with the symmetry of the droplet configuration, the geometry of the droplet arrangement plays a dominate role in the nonmonotonic change. The maximum energy conversion efficiency is just over 6.5% and the minimum is just under 3%. The findings of this study not only reveal how the arrangement affects ternary droplet jumping and explain the phenomenon that cannot be explained before, but deepens our understanding of multi-droplet jumping as well. [ABSTRACT FROM AUTHOR]

When the bright green-emitting SrAl2O4:Eu,Dy persistent phosphor was described in the literature in 1996, this presented a real breakthrough in performance, both in terms of initial brightness and afterglow duration. Since then, many new persistent phosphors, with emission spanning from the ultraviolet to the near infrared, have been developed. Very few materials, however, reach a similar afterglow time and intensity as SrAl2O4:Eu,Dy, which is still considered the benchmark phosphor. The present paper discusses the reasons for this—seemingly—fundamental limitation and gives directions for further improvements. An overview is given of the preparation methods of persistent phosphors and their properties. Much attention is paid to the correct evaluation of a persistent phosphor in absolute units rather than vague terms or definitions. State of the art persistent phosphors are currently used extensively in emergency signage, indicators, and toys. Many more applications could be possible by tuning the range of trap depths used for energy storage. Very shallow traps could be used for temperature monitoring in, for example, cryopreservation. Deeper traps are useful for x-ray imaging and dosimetry. Next to these applications, a critical evaluation is made of the possibilities of persistent phosphors for applications such as solar energy storage and photocatalysis. [ABSTRACT FROM AUTHOR]

Solar-blind photodetectors are critically important for civil and military applications. Several of these applications, such as space exploration and nuclear energy infrastructure, demand the use of a photodetector under extreme environments. In this paper, we have studied the radiation hardness and device performance of amorphous and polycrystalline gallium oxide thin films against heavy ion (Ag7+) irradiation with a high energy of 100 MeV. Gallium oxide thin films show great tenacity against massive and highly energetic ions. The amorphous and polycrystalline phases undergo structural and morphological changes that initially induce degradation in the device performance. Nano-pore like structures are formed in the amorphous film, while the polycrystalline film shows the destruction of large crystallites. The responsivity of the photodetector device reduces fourfold in the amorphous phase; however, a sixfold reduction in the performance is observed in the polycrystalline phase of the gallium oxide photodetector. The degradation is attributed to the annealing of pre-existing optical defects that are otherwise responsible for the huge photoconductive gain in the detector and confirmed by photoluminescence studies. The effect of self-annealing at room temperature and annealing at moderate temperature is investigated to recover the irradiated photodetector devices. Partial recovery in the polycrystalline based photodetector and two orders of magnitude enhanced responsivity and an almost twice faster response time compared to the control photodetectors in the amorphous phase are observed. This work investigates the effect of heavy and energetic ions on the performance of gallium oxide based solar-blind photodetector and provides the guideline to use high energy irradiation as a tool for defect engineering. [ABSTRACT FROM AUTHOR]

Darwin approximation, a non-relativistic submodel of the Maxwell's equations, has been used for theoretical and computational investigations of magnetized plasmas. In this short paper, an improved Darwin approximation is proposed, which is applicable not only to the Coulomb gauge but also to the Lorenz counterpart. The proposed approximation exactly satisfies the conservation of charge, momentum, and energy under the use of the Lorenz and Coulomb gauges. [ABSTRACT FROM AUTHOR]

MEMS electric energy utilization rate is the key parameter affecting firing performance. It has important relationship with its preparation technology, microscale and structure morphology. In order to improve the theory of energy exchange element design for MEMS pyrotechnics, reduce the design error of transducer parameters at microscale. To ensure the performance of MEMS pyrotechnics, in this paper, the influence of the central line of the thin film transducer element on the electrothermal conversion is simulated and analyzed. The electrothermal conversion and temperature characterization of different central lines in the transducer bridge area are calculated by the finite element method. The influence of the central line on the thermal efficiency under microscale is revealed. The corresponding data are obtained. [ABSTRACT FROM AUTHOR]

The use of renewable energy, notably solar and wind energy, has grown exponentially in Brazil. Consumers can generate their energy using renewable sources, whether interconnected to the distribution system (on-grid) or not (off-grid). In this paper, a fuzzy method is developed for the recommendation of solar and wind sources, for any location in the Brazilian territory. In many aspects, it can be viewed as a representation of human decision-making using sets and inference rules and also can be with vagueness and uncertainty, being very useful to idealize recommendation systems. Georeferenced and historical data were obtained from 2003 to 2019 on solar irradiation and wind speed, and electricity consumption until 2021. With the energy generation data from photovoltaic panels and wind turbines, this method allows us to propose installed areas by each technology and obtain the membership of fuzzy recommendation between solar, wind, both solar and wind, unfeasible or hybrid. In addition, a long short-term memory neural network and the seasonal autoregressive integrated moving average model were used to predict consumption for more than 30 months ahead, allowing the recalculation of fuzzy memberships and updating the installation area by respective technologies. As a result, the recommendation is given as the installed area (m2) of each technology per km2 of consumer units, as a function of the regional consumption density (MWh/km2). It can be concluded that it is possible to plan the viability of the type of renewable energy used, according to regional characteristics for smaller consumer units (farms, cooperatives, industries, consortiums), given the diversity of these factors in the huge Brazilian territory. This methodology is in line with the Brazilian Normative Resolution that authorizes the generation of energy by landowners. [ABSTRACT FROM AUTHOR]

Coalescence-induced droplet jumping on superhydrophobic surfaces has attracted significant attention in recent years. In this paper, by using a three-dimensional multiphase lattice Boltzmann model, we numerically investigated the droplet jumping on V-shaped groove superhydrophobic surfaces induced by the coalescence between two droplets located in the asymmetric V-shaped groove. First, it is found that the self-jumping process gradually becomes inefficient when the groove angle decreased, which is caused by the increasing viscous dissipation with the decrease in the groove angle. In order to overcome the weakness of the V-shaped superhydrophobic surface and enhance the droplet jumping performance, an improved V-shaped superhydrophobic surface with a triangular prism was conceived. Numerical results showed that the normalized jumping velocity and the energy conversion efficiency of the V-shaped superhydrophobic surface with a triangular prism can be increased by up to 80% and 210%, respectively, in comparison with those of the surface without the triangular prism. The jumping enhancement mainly arises from the combined effect of the redirection of the expanding liquid bridge by the V-shaped sidewalls, as well as the earlier and sufficient impact of the liquid bridge on the triangular prism in the groove. Moreover, using the improved V-shaped superhydrophobic surface, a guided jumping can be achieved due to the reaction forces exerted by the V-shaped sidewalls and the triangular prism, and the jumping angle can be more accurately predicted based on the groove angle. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to analyze the effects of the heave motion of an elastically supported floating oscillating water column device (OWC) on wave energy harvesting efficiency through two-dimensional computational fluid dynamics simulations. After the numerical model is validated using experimental data, it is used to analyze the effect of the natural frequency ratio on the hydrodynamic efficiency of the OWC. The natural frequency ratio is the ratio of the natural frequency to the wave frequency. The numerical results prove that the natural frequency ratio must be greater than 3 for achieving the best hydrodynamic efficiency. The best hydrodynamic efficiency decreases with the decrease in the natural frequency ratio when the latter is 3. If the natural frequency ratio is smaller than 3, both the amplitudes of wave surface elevation and the displacement of the OWC chamber increase but the harvested energy reduces because the relative motion of the wave surface and the OWC device is small. The energy dissipation due to vortices does not have a strong contribution to the reduction of energy at small natural frequencies. [ABSTRACT FROM AUTHOR]

Electromechanical metamaterials have been the focus of many recent studies for use in simultaneous energy harvesting and vibration control. Metamaterials with quasiperiodic patterns possess many useful topological properties that make them a good candidate for study. However, it is currently unknown what effect electromechanical coupling may have on the topological bandgaps and localized edge modes of a quasiperiodic metamaterial. In this paper, we study a quasiperiodic metamaterial with electromechanical resonators to investigate the effect on its bandgaps and localized vibration modes. We derive here the analytical dispersion surfaces of the proposed metamaterial. A semi-infinite system is also simulated numerically to validate the analytical results and show the band structure for different quasiperiodic patterns, load resistors, and electromechanical coupling coefficients. The topological nature of the bandgaps is detailed through an estimation of the integrated density of states. Furthermore, the presence of topological edge modes is determined through numerical simulation of the energy harvested from the system. The results indicate that quasiperiodic metamaterials with electromechanical resonators can be used for effective energy harvesting without changes in the bandgap topology for weak electromechanical coupling. [ABSTRACT FROM AUTHOR]

This paper studies the thermal conduction of Frenkel–Kontorva (FK)-ϕ4 lattices with the finite number of atoms under a periodic force. Through numerical simulations, we find that in the thermal conduction of non-linear lattices, external periodic signals can act in conjunction with noise to create stochastic resonance behaviors and that some adjustable dynamical parameters, such as the onsite potential of the FK and ϕ4 lattices, the amplitude and frequency of external periodic signals, can regulate heat flux. Our study results can provide a sufficient theoretical basis for the fabrication of thermal devices and the control and utilization of thermal energy. [ABSTRACT FROM AUTHOR]

With the ever-growing demands for sampling rate, conversion resolution, as well as lower energy consumption, the memristor-based neuromorphic analog-to-digital converters (MN-ADC) becomes one of the most potential approaches to break the bottleneck for traditional ADCs. However, the online trainable MN-ADCs are not designed to be easily integrated into the 1T1R crossbar array, meanwhile suffering from the device non-idealities, which makes it difficult to realize high-speed and accurate conversion. To overcome these issues, this paper proposes a high-reliable 2T2R synaptic structure. And through the dedicated structure, we construct a 4-bit MN-ADC that allows for alternate conversions and online adjustments in a single clock period, which can significantly mitigate the effects of device non-idealities on dynamic performance. More importantly, this structure can be perfectly compatible with 1T1R crossbar arrays. Simulation results demonstrate the validity of the proposed MN-ADC, which achieves the ENOB of 3.77 bits, the INL of 0.16 LSB, and the DNL of 0.07 LSB. [ABSTRACT FROM AUTHOR]

Soft chemo-mechanical (SCM) machines convert chemical energy into mechanical energy. They have the advantages of fast actuation and compliant deformation and possess wide applications in soft robots and flexible smart devices. Using experiments and theoretical modeling, this paper investigates the chemo-mechanical energy flows and the energy conversion cycle in the pressure and volume (P–V) plane of an SCM machine consisting of a soft membrane and cylindrical chambers. The machine generates 16.1 mJ of mechanical energy per cycle. We study heat dissipation as the key issue affecting the conversion efficiency. The states of the conversion cycle calculated from mechanical modeling fit well with those measured experimentally. The design principles and the theoretical methods can be used to guide the fabrication and characterization of SCM actuators and robots. [ABSTRACT FROM AUTHOR]

This paper comprehensively reviews the state of the art of Heating, Ventilation, and Air-Conditioning (HVAC) control sensing. The topic has broad impacts on society, by affecting energy consumption, Earth's climate, and the environmental health. Great effort was taken by researchers to study and test new technologies and methodologies for improving HVAC energy efficiency, but this large amount of works is often fragmentary, and a complete and recent review paper does not yet exist. This paper aims at filling this gap by clarifying the key points of HVAC sensing, the main technologies, and their pros and cons. The advancement in this sector is fueled by the premium performance of the embedded systems exploited as sensors and their beneficial features. The state of the art of the available solutions has been summarized with the purpose of fueling and better organizing the research effort on this hot topic. Particular attention has been paid to investigate not only the performance and reliability of the current systems but also the advanced features that can be provided by the newly evolved and complex technologies, e.g., the radar technology that has been identified as the emerging one in this field. [ABSTRACT FROM AUTHOR]

In this work, a pair of sweeping jet actuators is installed underneath the endplate of a slanted-base cylinder at ReD = 200 000. The sweeping jets form a 30° inclined angle with the endplate and are placed at different streamwise locations, and their strength is varied with a momentum coefficient, Cμ, ranging from 3.8 × 10−3 to 6.0 × 10−2. For all the cases examined in this paper, it is found that while a higher Cμ produces a higher drag reduction, the flow control energy efficiency decreases rapidly as Cμ increases. A net energy saving is achieved when Cμ is less than 0.01, and the highest energy efficiency obtained in the present study is 2.8% when the actuator pair is placed at the most upstream location tested. The drag reduction is attributed to the reaction force and an increase in the surface pressure force acting on the endplate produced by the jet pair. The contribution from the former constitutes an increasing proportion of the total drag reduction as Cμ increases leading to lower energy efficiency in flow control. Depending on the relative positions between the trajectory of the sweeping jet and afterbody vortex, sweeping jets are not only capable of altering the surface pressure distributions via directly imposing a footprint of high pressure on the surface, but also affecting the roll-up of the afterbody vortex and/or reducing its strength via injecting turbulence into the afterbody vortex. [ABSTRACT FROM AUTHOR]