Additional Energy Consumption Research Articles

Experimental assessment of the ice protection effectiveness of icephobic coatings for a hovering drone rotor

A new installation at the Anti-Icing Materials International Laboratory was developed to study the effects of icing on the degradation of a hovering drone rotor aerodynamic performance and to test different potential ice protection solutions. Following a study on icing parameters effects on aerodynamic performance, this paper studies a methodology developed to assess the performances of coatings as a potential ice protection system under severe icing conditions and rotor speeds up to 4950 RPM. Four different coatings, commercial or under development, were applied to the rotor blades and their effect on the resulting ice accumulation and aerodynamic degradation were measured and compared to those previously obtained on similar, uncoated blades. Results show that passive icephobic coatings in general are a promising solution to limit the negative effect of icing conditions for drone applications, without any additional energy consumption from the system. Moreover, the repeatability assessment of tests under similar conditions and for the same coating showed agreement within ±5% between repetitions, showing no signs of ice protection efficiency degradation for any of the tested coatings.

An In-Module Disturbance Barrier for Mitigating Write Disturbance in Phase-Change Memory

Write disturbance error (WDE) appears as a serious reliability problem preventing phase-change memory (PCM) from general commercialization, and therefore several studies have been proposed to mitigate WDEs. Verify-and-correction (VnC) eliminates WDEs by always verifying the data correctness on neighbors after programming, but incurs significant performance overhead. Encoding-based schemes mitigate WDEs by reducing the number of WDE-vulnerable data patterns; however, mitigation performance notably fluctuates with applications. Moreover, encoding-based schemes still rely on VnC-based schemes. Cache-based schemes lower WDEs by storing data in a write cache, but it requires several megabytes of SRAM to significantly mitigate WDEs. Despite the efforts of previous studies, these methods incur either significant performance or area overhead. Therefore, a new approach, which does not rely on VnC-based schemes or application data patterns, is highly necessary. Furthermore, the new approach should be transparent to processors (i.e., in-module), because the characteristic of WDEs is determined by manufacturers of PCM products. In this paper, we present an in-module disturbance barrier (IMDB) that mitigates WDEs on demand. IMDB includes a two-level hierarchy comprising two SRAM-based tables, whose entries are managed with a dedicated replacement policy that sufficiently utilizes the characteristics of WDEs. The naive implementation of the replacement policy requires hundreds of read ports on SRAM, which is infeasible in real hardware; hence, an approximate comparator is also designed. We also conduct a rigorous exploration of architecture parameters to obtain a cost-effective design. The proposed method significantly reduces WDEs without noticeable speed degradation or additional energy consumption compared to previous methods.

Airflow uniformity and energy consumption investigation on data centers enhanced by jet fans

Active adjustment of the airflow organization in data centers (DC) has been increasingly applied due to its superior adjustment performance. But for now, the main focus is on the airflow distribution optimization in the horizontal direction, while few research has been conducted to investigate the additional energy consumption of active method. This paper introduced the jet-induced ventilation into under-floor air distribution (UFAD), then the coupling air supply system (CASS) was established. Taking the CASS data center as an example, this paper focuses on the impact of the active adjustment method on both airflow organization and energy consumption of the DC, and analyzes the energy consumption of the system while meeting the security operations of the thermal environment. The results showed that the incorporation of jet-induced ventilation effectively improved the airflow distribution uniformity, while the active adjustment of the airflow organization in the DC has little effect on the overall energy consumption. On the premise of meeting the demand of thermal environment, the energy consumption of the CRAC (Computer room air conditioning) units in the CASS is reduced and the change of the overall energy consumption is small, while the total energy consumption increased with the increase of airflow uniformity.

Air Conditioning Operation Strategies for Comfort and Indoor Air Quality in Taiwan’s Elementary Schools

The Executive Yuan in Taiwan plans to install air-conditioning (A/C) in all elementary schools within two years. However, besides the associated energy consumption and environmental issues, the use of A/C will inevitably result in the doors and windows of the classroom being closed, which will increase the accumulation of carbon dioxide (CO2) within the classroom. An excessive indoor CO2 concentration can result in reduced cognitive performance and an impaired learning efficiency. Therefore, the moderate introduction of external air into the classroom is essential to increase the air exchange rate (AER) and reduce the CO2 concentration level. Accordingly, the present study conducts a numerical investigation into the effects of various A/C operation strategies on the CO2 concentration within the classroom given different proportions of students remaining in the classroom during the recess. Overall, the results indicate that the optimal usage strategy is to operate the A/C over the full school day (08:00~15:50 p.m.) in conjunction with a mechanical ventilation system providing a fresh air exchange rate of 5 l/s for every person in the room. However, the use of a mechanical ventilation system inevitably incurs an additional hardware and energy consumption. Thus, an alternative recommendation is also proposed, in which the windows are opened and the air conditioner is turned off at every recess and during the lunchtime period. It is shown that the resulting CO2 concentration in the classroom is still consistent with the Taiwan Environmental Protection Administration (EPA) regulations and the thermal comfort of the students is achieved for more than three-quarters of the school day.

Energy-saving Service Offloading for the Internet of Medical Things Using Deep Reinforcement Learning

As a critical branch of the Internet of Things (IoT) in the medicine industry, the Internet of Medical Things (IoMT) significantly improves the quality of healthcare due to its real-time monitoring and low medical cost. Benefiting from edge and cloud computing, IoMT is provided with more computing and storage resources near the terminal to meet the low-delay requirements of computation-intensive services. However, the service offloading from health monitoring units (HMUs) to edge servers generates additional energy consumption. Fortunately, artificial intelligence (AI), which has developed rapidly in recent years, has proved effective in some resource allocation applications. Taking both energy consumption and delay into account, we propose an energy-aware service offloading algorithm under an end-edge-cloud collaborative IoMT system with Asynchronous Advantage Actor-critic (A3C), named ECAC. Technically, ECAC uses the structural similarity between the natural distributed IoMT system and A3C, whose parameters are asynchronously updated. Besides, due to the typical delay-sensitivity mechanism and time-energy correction, ECAC can adjust dynamically to the diverse service types and system requirements. Finally, the effectiveness of ECAC for IoMT is proved on real data.

Development of a new type of household appliances – refrigerators with a heating chamber

The object of this study is absorption-type refrigeration appliances, which allow to expand the functionality of household appliances without additional energy consumption.
 Investigated problem: The aim of this study: firstly, due to the novelty of the proposed technique, it was necessary to show the real possibility of obtaining the temperature level required for technological processes (up to 70 °C); secondly, taking into account the experience gained in experimental studies, it was necessary to propose new designs for solving the problems of refrigeration and heat treatment of food products and raw materials in domestic conditions.
 The main scientific results: It is shown that the development of devices that combine the functions of refrigeration storage and heat treatment of food products, semi-finished products and agricultural raw materials can become a promising area for energy saving in household appliances. In such household combined appliances, the heat released during the implementation of the refrigeration cycle is not immediately removed to the environment, but is transferred to a special heating chamber, while the temperature in the volume of the heating chamber is maintained higher than the air temperature in the room. The effect of energy saving is achieved by expanding the functionality of household appliances without attracting additional energy costs.
 The original designs of combined absorption-type household appliances are proposed, a description of their operation, advantages and disadvantages, and areas of application are given.
 The area of practical use of the research results: In the course of experimental studies, it was shown that the introduction of an additional heating chamber into the structure of household absorption refrigerators, thermally connected with the lifting section by the dephlegmator of the absorption refrigeration unit, does not lead to an increase in energy consumption (according to the test results below than in the standard version by 5 %) and does not impair the performance of the cooling chambers.
 The area of practical use of the research results: household energy-saving appliances.
 Innovative technological product: the use of an evaporation-condensation cycle that provides highly efficient heat transfer at a distance of up to 1 meter from the heat dissipation zone of the refrigeration unit to the usable volume of the heating chamber of the household appliance.

Novel Passive Radiation Cooling Materials with High Emissivity Discovered by FDTD Method

The cooling with the traditional condensation method leads to huge energy consumption, while increasing attention has been paid to radiant cooling because of its characteristics of no additional energy consumption and no pollution. In order to obtain materials with higher infrared emissivity and better performance for daytime passive radiation cooling materials, the infrared emissivity of different materials was studied based on the finite-difference time-domain method. A new composite material with high emissivity has been found. The results show that the highest emissivity can reach 99.1% by adding Si3N4, Al2O3 and Fe2O3 particles with volume fractions of 6% and diameters of 50 nm into polydimethylsiloxane. This is the most excellent emissivity ever found. By combining the emitting layer made of polydimethylsiloxane mixed with nanoparticles with the reflecting layer made of Ag foil, the new film material can reach a solar transmissivity of 96.4% and a “sky window” mean emissivity of 94.2%. A new composite material with high emissivity and high reflectivity has been realized. The new composite material can be used as a radiation cooling material with good performance and help to solve the cooling problem caused by energy consumption.

Recent advances in magnesium-based materials: CO2 sequestration and utilization, mechanical properties and environmental impact

Cement industry is one of the main sources of greenhouse gases, which accounts for about 7% of global CO2 emissions. Sequestration of CO2 in cement-based materials is regarded as an effective alternative since it can convert CO2 into stable carbonates with relatively low additional energy consumption. This paper presents a comprehensive review on recent research and advances on carbon sequestration in magnesium-based binders with a focus on reactive MgO cement (RMC) and magnesium oxychloride cement (MOC). The carbon sequestration mechanism, the influence of carbonation on mechanical performance, and key parameters that control the carbonation process are summarized. In addition, a quantitative analysis of carbon sequestration in RMC-based materials is presented, demonstrating the effectiveness of offsetting carbon emissions via the use of alternative binder systems. Furthermore, a comparison of the environmental impact of Portland cement, RMC and MOC production is provided, emphasizing the need for enhancing the sustainability of cement production procedures. Overall, this paper presents a roadmap for emerging carbonation techniques that improve the mechanical performance and sustainability of magnesium-based binders.

Thermally treated coal mining waste as a supplementary cementitious material – Case study from Bogdanka mine, Poland

The presented study deals with the comprehensive analysis of coal gangue from the Bogdanka mine (Lubelski Węgiel „Bogdanka" S.A.) in terms of its properties in both raw and activated states, and with the evaluation of the functional parameters of blended cement pastes containing 10 wt%, 15 wt%, and 20 wt% of thermally treated mining waste. The assessment of the raw material included chemical, physical, mineralogical, and morphological characterization, thermogravimetry, and pozzolanic activity tests. The motivation for the research was the intention to utilize a significant amount of waste from the Bogdanka mine with low additional energy consumption for processing. For this purpose, the temperature of 600 °C was chosen for its thermal activation based on the simultaneous thermal analysis (STA) measurement. The activated coal gangue was tested in the same way as the raw materials and then applied in the blended cement pastes as a partial cement substitute. The cement pastes were evaluated in the fresh state (flow table test), and also at the age of 7, 28, and 90 days. The structural, microstructural, mechanical, and hygric parameters were investigated and compared with the plain cement paste. Furthermore, the development and rate of the pozzolanic reaction were studied using simultaneous thermal analysis with mass spectrometry (STA-MS), X-Ray diffraction (XRD), isothermal calorimetry, and assessment of strength activity index (SAI). The performed analyses gave evidence of the pozzolanic activity of thermally activated coal mining waste (ACMW) from the Bogdanka mine and its effectiveness in cement blends. The slightly dropped hydration degree was later compensated by prolonged curing time and progress in the pozzolanic reaction. The blending of Portland cement with the examined ACMW did not negatively affect the rheology and setting time of fresh blended pastes. Considering the hardened cement blends' structural, microstructural, and mechanical parameters, ACMW can be safely used as a part of a PC-based blended binder for up to 20% replacement of cement mass.

Evaluation of Heated Window System to Enhance Indoor Thermal Comfort and Reduce Heating Demands Based on Simulation Analysis in South Korea

Heated glass can be applied to improve windows’ condensation resistance and indoor thermal comfort in buildings. Although this applied technology has advantages, there are still some concerns in practical applications, such as additional energy consumption and control issues. This study evaluates the effectiveness of a heated window heating (HWH) system in terms of thermal comfort and heating energy performance (HEP). The simulation-based analysis is performed to evaluate the effectiveness of the HWH using a residential building model and to compare it with radiant floor heating (RFH) and hybrid heating (HH) systems (i.e., combined HWH and RFH). This study also investigates the peak and cumulative heating loads using HWH systems with various scenarios of control methods and setpoint temperature. The predicted mean vote (PMV) is used as an indoor thermal comfort index. The ratio of cumulative thermal comfort time to the entire heating period is calculated. The results show that HWH and HH can reduce the heating load by up to 65.60% and 50.95%, respectively, compared to RFH. In addition, the times of thermal comfort can be increased by 12.55% and 6.98% with HWH and HH, respectively. However, considering the social practices of South Korea, HH is more suitable than HWH. Further investigations for HH show that a surface setpoint of 26 °C is proper, considering both heating demands and thermal comfort. In addition, the setpoint temperature should be determined considering HEP and the thermal comfort for HWH, and the optimal setpoint temperature was suggested under specific conditions.

Battery thermal management strategy utilizing a secondary heat pump in electric vehicle under cold-start conditions

When an energy storage system (ESS) operates in cold conditions, the power and capacity of the battery critically fade. Therefore, an appropriate battery thermal management strategy (BTMS) is essential to prevent severe driving range loss at low ambient temperatures. However, none of existing studies considered the effect of BTMS on the driving range from a systematic perspective. Thus, we evaluated the trade-off between the performance enhancement by ESS heating and the additional energy consumption for ESS heating. We suggested and analyzed three BTMSs combined with a secondary heat pump: self-heating, active heating, and heat recovery. Active heating of the battery augmented the driving range of the EV by up to 18.8% over the self-heating strategy when the battery was used to full depletion, whereas the heat recovery strategy reduced the state-of-charge (SOC) decrease and thus increased EV driving range in nondepleted conditions. Furthermore, battery preheating with the heat pump achieved a temperature rise of 20 °C within an hour, consuming 38.4% less battery power than with conventional electric heater preheating. We expect this study contributes to the range extension of EV by suggesting the optimal BTMS depending on the driving conditions.

Energy-Aware Next-Generation Mobile Routing Chains with Fog Computing for Emerging Applications

The Internet of Things (IoT) provides robust services to connected sensors in a distributed manner, and maintains real-time communication using wireless standards. The smart network has offered many autonomous smart systems to collect information from remote nodes, and share it by exploring the network layer. Researchers have recently offered a variety of ways to increase the effectiveness of emerging applications using trustworthy relaying systems. However, there are still many issues with route reformulation due to frequent disconnections of mobile devices and resource limitations. Furthermore, most of the existing methods for IoT systems are unable to utilize network resources, which lowers the performance of green networks. Thus, providing a foolproof solution for the autonomous system with energy efficiency is a challenging task. Therefore, this paper presents an algorithm for the mobile network using fog computing to reduce network disconnectivity. Furthermore, using security services, the proposed algorithm efficiently explores the characteristics of the device, and avoids malicious traffic to drain the additional energy consumption of the network. The main aspects of the proposed algorithm are as follows: (i) using the adjustable transmission power, the proposed algorithm offers a fault-tolerant solution to transmit the aggregated data over the unpredictable wireless system; (ii) with the support of fog nodes, the data load is reduced among devices with the offering of a secured authentication scheme. Using simulations, the proposed algorithm is tested, and its significance is demonstrated against other related studies.

Determination of interlayer crack resistance of stitched thin-sheet epoxy carbon composites using wedge delamination (wedging) technique

The local indices of the crack resistance of a thin-sheet reinforced polymeric carbon composite (CCM) stitched with glass and aramid threads with a double lockstitch were determined by wedging in the framework of linear elastic fracture mechanics under loading mode I using standard samples in the form of a double cantilever beam (DCB). Different number of stitches and stitching lines were used for different directions of crack propagation relative to the laying of the reinforcing fabric and stitches. It is shown that regardless of the type of stitching thread and the crack propagation direction, the average and normalized (relative to non-stitched samples) values of the local crack resistance parameters of stitched CCM samples mostly depend on the crack propagation area and on the density (pitch) of stitching responsible for a pronounced locality and anisotropy of the crack resistance. The highest resistance to crack propagation is observed in the areas of interweaving of the stitching threads as a result of additional energy consumption for deformation and breaking of stitching threads, and the lowest one is characteristic of the areas between stitches along the stitch or step between lines, both in the longitudinal and perpendicular directions of the crack propagation relative to the laying of the fabric and stitching lines. When evaluating the specific average values of the parameters of the local crack resistance of CCM samples related to one line of stitching with a longitudinal crack propagation or to one stitch when a crack propagates across the stitching lines, the effect of increased local crack resistance in the areas of interlacing of threads turns out to be significantly weaker, whereas this decrease in stitch areas and between the stitching lines is significantly more pronounced. For more accurate assessment of the crack resistance of a thin-sheet stitched CCM, it is advisable to determine and use specific local parameters taking into account scale effects.

Research on the Prediction of Insertion Resistance of Wheel Loader Based on PSO-LSTM

Insertion resistance is the resistance caused by a pile to a wheel loader when the latter inserts into the pile. It is significant to clarify the insertion resistance to avoid wheel slippage, increase additional energy consumption, and protect the wheel loader during the insertion process. To address the problem that current methods cannot accurately obtain the insertion resistance magnitude and insertion resistance variation trend, we propose a composite model based on the particle swarm optimization (PSO) algorithm and the long short-term memory (LSTM) neural network. Firstly, the Pearson correlation coefficient method is used to test the parameters related to insertion resistance. Following this, the hyperparameters in the LSTM are optimized by PSO. Finally, different proportions of training sets are set in PSO-LSTM and compared with LSTM. The experimental data are selected from gravel sample groups and sand sample groups consisting of insertion depths of 600 mm, 800 mm, and 1000 mm. The results show that PSO-LSTM has higher prediction accuracy, better robustness, stability, and generalization ability compared with LSTM. In PSO-LSTM, when the proportion of the training set is 80%, the average relative errors are 2.28%, 1.57%, and 1.53% for the gravel sample group and 1.14%, 0.71%, and 0.60% for the sand sample group.

Study of seat-to-head vertical vibration transmissibility of commercial vehicle seat system through response surface method modeling and Genetic Algorithm

Low-frequency vibration is a significant hazard to commercial vehicle drivers. Research on how to reduce seat vibration and improve human comfort in a seating system through seat design optimization is important. The novelty of this paper is to study the sensitivity analysis of seat design parameters and their interaction effects and optimize seat design for the minimum vibration transmission to human drivers. The uniqueness of this paper is the identification of the system parameters from the measured vibration acceleration data rather than from the material test.The purpose of this paper is to develop a prediction model of vibration transmissibility from input design parameters using the response surface method modeling. The statistical significance of the RSM model will be validated by analysis of variance. The design parameters will be optimized through the RSM modeling and Genetic Algorithm.The method can enhance the vibration isolation performance of the existing vehicle seat suspension system with reduced cost and without additional parts and energy consumption and make the design change and optimization of the seat suspension system simple and easy to be implemented. According to the research results, the vibration transmissibility ratio of the optimized seat system is reduced by about 10%.

Optimal Energy Consumption and Response Capability Assessment for Hydraulic Servo Systems Containing Counterbalance Valves

Abstract Counterbalance valves (CBVs) are broadly applied in hydraulic manipulators, which is essential to ensure safe operation while moving a heavy load. They inevitably introduce additional energy consumption and poor dynamic performance. For the manipulator joint in tunnel boring machines, smooth and precise motion control has to be realized. However, for the forward design considerations, in this case, no systematic work has been done to determine the component parameters based on an energy-saving approach and to derive the natural frequency of the joint at the hydraulic level. To fill this gap, this paper proposes a forward design approach for the proportional valve-controlled hydraulic cylinder system containing CBVs, which is a basic hydraulic configuration adopted for the manipulator joint. Specifically, the optimization model aiming at the minimum energy consumption is defined and improved to solve the key parameters, including the pilot ratio of the CBV and the area ratio of the cylinder. By considering constraints, the other component parameters could be further calculated. After that, the theoretical derivation of natural frequency is given to evaluate the response capability of the system. The overall design procedure is presented to determine the cylinder, CBV, control valve, and constant pressure supply. Based on the validated numerical model, the energy-based design principle is proven effective and could ensure that energy saving is not less than 5% and not more than 36% on average. Furthermore, the natural frequency obtained by the sweep test is verified to be consistent with the theoretical value, and the impact of this parameter on control performance is analyzed. The results indicate that the proposed approach has an excellent guide for the forward design of such systems.

A Lossless Soft-Switching Boost Converter with Passive Auxiliary Circuit

Based on boost topology, a lossless soft-switching passive circuit with a single switch is proposed in this paper. The proposed circuit's power switch achieves approximately zero voltage switching (ZVS) and zero current switching (ZCS) without increasing the number of switches. Due to an auxiliary inductor, the reverse recovery loss of the rectifier diode is significantly reduced. Besides, all auxiliary circuit energy is returned to the power supply without additional energy consumption. Therefore, by using a traditional control method, simple design, and appropriate auxiliary circuit parameters, soft-switching can be realized in a wide voltage and full load range. Moreover, the number of components used in the auxiliary circuit is minimal. This method makes circuit design more manageable and achieves 95.39% high efficiency since the increase of voltage stress is relatively small.

A robust and 3D-printed solar evaporator based on naturally occurring molecules

The interfacial solar desalination has been considered a promising method to address the worldwide water crisis without sophisticated infrastructures and additional energy consumption. Although various advanced solar evaporators have been developed, their practical applications are still restricted by the unsustainable materials and the difficulty of precise customization for structure to escort high solar-thermal efficiency. To address these issues, we employed two kinds of naturally occurring molecules, tannic acid and iron (III), to construct a low-cost, highly efficient and durable interfacial solar evaporator by three-dimensional (3D) printing. Based on a rational structural design, a robust and 3D-printed evaporator with conical array surface structure was developed, which could promote the light harvesting capacity significantly via the multiple reflections and anti-reflection effects on the surface. By optimizing the height of the conical arrays, the 3D-printed evaporator with tall-cone structure could achieve a high evaporation rate of 1.96 kg m–2 h−1 under one sun illumination, with a photothermal conversion efficiency of 94.4%. Moreover, this evaporator was also proved to possess excellent desalination performance, recycle stability, anti-salt property, underwater oil resistance, as well as adsorption capacity of organic dye contaminants for multipurpose water purification applications. It was believed that this study could provide a new strategy to fabricate low-cost, structural regulated solar evaporators for alleviating the dilemma of global water scarcity using abundant naturally occurring building blocks.

Handover Decision Making for Dense HetNets: A Reinforcement Learning Approach

In this paper, we consider the problem of decision making in the context of a dense heterogeneous network with a macro base station and multiple small base stations. We propose a deep Q-learning based algorithm that efficiently minimizes the overall energy consumption by taking into account both the energy consumption from transmission and overheads, and various network information such as channel conditions and causal association information. The proposed algorithm is designed based on the centralized training with decentralized execution (CTDE) framework in which a centralized training agent manages the replay buffer for training its deep Q-network by gathering state, action, and reward information reported from the distributed agents that execute the actions. We perform several numerical evaluations and demonstrate that the proposed algorithm provides significant energy savings over other contemporary mechanisms depending on overhead costs, especially when additional energy consumption is required for handover procedure.

A novel passive shoulder exoskeleton for assisting overhead work.

Shoulder exoskeletons (SEs) can assist the shoulder joint of workers during overhead work and are usually passive for good portability. However, current passive SEs face the challenge that their torque generators are often attached to the human arm, which adds a significant amount of weight to the user's arms, resulting in additional energy consumption of the user. In this paper, we present a novel passive SE whose torque generator is attached to the user's back and assists the shoulder joint through Bowden cables. Our approach greatly reduces the weight on the user's arms and can accommodate complex shoulder joint movements with simple and lightweight mechanical structure based on Bowden cables. In addition, to match the nonlinear torque requirements of the shoulder joint, a unique spring-cam mechanism is proposed as the torque generator. To verify the effectiveness of the device, we conducted a usability test based on muscle activations of 10 healthy subjects. When assisting overhead work, the SE significantly reduced the mean and maximum electromyography signals of the shoulder-related muscles by up to 25%. The proposed SE contributes to further research on passive SE design to improve usability, especially in terms of reducing weight on human arms.