Cumulative Energy Consumption Research Articles

Admission Control in Home Energy Management Systems Using Theatre and Hybrid Actors

The goal of a Home Energy Management System (HEMS) is that of purposely shaping the cumulative energy consumption curves of domestic appliances by imposing suitable monitoring and control policies. The development of HEMS, like the development of general Cyber-Physical Systems (CPSs), is challenging, as it requires the exploitation of suitable methodological approaches which are able to deal jointly with the continuous and discrete behaviours of a CPS. In this paper, a methodological approach for HEMS is advocated which relies on the use of the Theatre actor system with hybrid actors. As a key feature, Theatre enables the same actor model to be used during the analysis, design, prototyping and implementation phases of the system. For property assessment, a Theatre model is reduced to Uppaal hybrid timed automata for analysis by statistical model checking. As a significant modelling example, a HEMS is proposed which implements an admission control strategy able to maintain the in-home energy consumption under a given threshold. Instead of reacting to an overload condition, the strategy is able to prevent an overload upfront by predicting the effect that the admission of a new load will have on the consumption curve of the whole system.

Immersive Robotic Telepresence for Remote Educational Scenarios

Social robots have an enormous potential for educational applications and allow for cognitive outcomes that are similar to those with human involvement. Remotely controlling a social robot to interact with students and peers in an immersive fashion opens up new possibilities for instructors and learners alike. Using immersive approaches can promote engagement and have beneficial effects on remote lesson delivery and participation. However, the performance and power consumption associated with the involved devices are often not sufficiently contemplated, despite being particularly important in light of sustainability considerations. The contributions of this research are thus twofold. On the one hand, we present telepresence solutions for a social robot’s location-independent operation using (a) a virtual reality headset with controllers and (b) a mobile augmented reality application. On the other hand, we perform a thorough analysis of their power consumption and system performance, discussing the impact of employing the various technologies. Using the QTrobot as a platform, direct and immersive control via different interaction modes, including motion, emotion, and voice output, is possible. By not focusing on individual subsystems or motor chains, but the cumulative energy consumption of an unaltered robot performing remote tasks, this research provides orientation regarding the actual cost of deploying immersive robotic telepresence solutions.

Research on the Seismic Performance of the Prefabricated Reinforced Concrete Column with Steel Mortise and Tenon Connections

In this study, 6 prefabricated reinforced concrete columns with different lengths of connectors and thicknesses of the steel plate used in connectors and 1 cast-in-place reinforced concrete column were made, and then these specimens were tested under the low cycled reversed loading experiment to study the seismic performance of the prefabricated reinforced concrete columns with steel mortise and tenon connections. The failure mode, bearing capacity, ductility, stiffness degradation, and energy dissipation of the specimens were analyzed. The results show that compared with the cast-in-place specimens, the bearing capacity of the fabricated specimen is reduced by 5.77%–16.67%, but the ductility is increased by 11.28%–26.69%, and the cumulative energy consumption is increased by 3.40%–30.29%; the stiffness, bearing capacity degradation, and hysteretic behavior of the fabricated specimen under different displacement angles are less different from those of the cast-in-place specimens. When the length of the connector is 100 mm and the thickness of the steel plate used in the connector is 4 mm, the weld fracture may occur in the connection area of the fabricated specimen. The test results show that when the connector with a length of 100 mm is used, the thickness of the steel plate of the connector should not be less than 6 mm.

Efficiency Improvement of the Air Cooled Packaged Water Chiller Unit with Three-Phase Alternating Current Control Technology

A three-phase alternating current control technology (TPACCT) was proposed and applied to the compressor of an air cooled packaged water chiller unit (ACH) to maintain the stable operation of the air-conditioning system and reduce energy consumption. The proposed TPACCT mainly uses a Single-Chip microcomputer to perform the calculations of the self-developed program, and uses a silicon controlled rectifier (SCR) component to trigger the voltage phase angle of ACH. Due to the drop of the controlled voltage, the current value is reduced, and the corresponding ACH active power also drops. This study attempts to reach the dynamic balance of voltage and current of the compressor in the air-conditioning system under heavy-load operating conditions to obtain the best control parameters. This study also conducted a long-term day-to-day experiment of the compressor, mainly analyzing the cumulative energy consumption of ACH when operating in a single zone, and comparing the energy-saving effect of the proposed TPACCT with the case operating under mains electricity. Results show that the cumulative energy consumption is about 5% lower than that of mains electricity mode. Different energy-saving strategies are provided for air-conditioning systems that need to be maintained under heavy-duty operation for a long time.

Hierarchical Distribution System Adaptive Restoration With Diverse Distributed Energy Resources

Distributed energy resources (DERs) can be utilized as alternative power sources for fast service recovery in cases of distribution system outages. However, the diverse characteristics and stochastic nature of DERs impose challenges on the optimal operation of diverse resources during the restoration phase. In this article, we introduce a hierarchical structure to coordinate distribution system entities and propose an adaptive restoration strategy to sustain a reliable power supply to outage loads in an unbalanced distribution system utilizing DERs. An efficient system reconfiguration model is developed to guarantee the radiality of restoration islands. The flexibility of DERs is evaluated by a novel method that focuses on the cumulative energy consumption, the superiority of which is also proven. Model predictive control (MPC) is adopted to enable the adjustment of system topology and DER operation strategies based on up-to-date data. The performance of the proposed restoration model is validated on a modified IEEE 123-bus test system. Moreover, the effectiveness of the proposed novel flexibility assessment and the MPC-based adaptive restoration strategy are verified through comparative studies.

Seismic behaviour of full-scale prefabricated RC beam–CFST column joints connected by reinforcement coupling sleeves

This study evaluated a new type of joint for connecting reinforced concrete (RC) beams with a concrete-filled steel tube (CFST) column that consists of U-shaped steel end plates and longitudinal reinforcement coupling sleeves. The proposed joint configuration was designed to fully realise the advantages of prefabricated structures, including a short construction period, easy construction control and low environmental impact. Low-cycle reversed loading tests were conducted to evaluate the seismic behaviour of three full-scale joint specimens, namely a cast-in-place joint and two prefabricated RC beam–CFST column joints connected using reinforcement coupling sleeves. The results indicate that the prefabricated joints exhibited plumper load–displacement curves and a good connection behaviour. The prefabricated joints failed in bending, thereby resembling the failure of the cast-in-place RC beam–CFST column joint. The failure region was concentrated in the area outside of the U-shaped end plate. The coupling sleeve connection was reliable, and the plastic hinge at the beam end moved further outward. Compared to the cast-in-place joint, the prefabricated RC beam–CFST column joints exhibited a similar bending capacity. The ductility coefficients of the prefabricated RC beam–CFST column joints increased about 5.2% and 2.6%, respectively. The average energy dissipation coefficient increased by 0.71% and 1.74%. The cumulative energy consumption and working index showed no significant difference.

Characterisation and use of energy flexibility in water pumping and storage systems

Renewable energy integration in power systems and increasing electrification of energy demand create new challenges to which energy flexibility can provide effective solutions. Trough an innovative use of cumulative energy consumption curves, which represent the maximum and minimum energy limits, as well as the associated flexible energy consumption, this paper presents a methodology to characterise and use the energy flexibility provided by water pumping and storage systems (WPSS) in order to achieve specific objectives at different levels of power systems. The methodology is applied to a case study considering a real WPSS where energy flexibility is used to reduce electricity costs and support the operation of the power system during a wind generation curtailment event. Collected results show that savings around 16% can be achieved while reducing pumping cycles by 57%. Furthermore, the WPSS operation can be modified according to the needs of the power system using the available energy flexibility.

Application of a prechop technique using a reverse chopper in small pupil cataract surgery.

BackgroundTo analyze the value of a prechop technique for splitting the nucleus of the lens using a reverse chopper in small-pupil cataract surgeries. A prospective case-control study. Thirty-four cataract patients (34 eyes) who were treated in our center from March 2019 to December 2019 were enrolled and then divided into two groups: small pupil group (18 patients; 18 eyes) and normal pupil group (16 patients; 16 eyes).MethodsThe prechop technique was applied in both groups, and the patients were followed up for three months. The best-corrected visual acuity (BVCA), surgical complications, corneal endothelial cell loss, pupil function, operative time, and cumulative dissipated energy (CDE) were compared between these two groups, and the safety of the nucleus-chopping technique was evaluated. Data were analyzed using the SPSS 23.0 software packages. BVCA, surgical complications, rate of corneal endothelial cell loss, pupil function, operative time, and CDE.ResultsThe surgery was smooth in all cases. The operative time, intraoperative ultrasound energy consumption, BVCA, and surgical complications indicated no significant difference between the two groups (all P>0.05). In the small pupil group, BVCA was significantly improved after surgery and achieved its optimal value three months after surgery (χ2=49.38; P=0). The diameter of the pupil was about 3.22 mm in the small pupil group before nucleus chopping. The postoperative pupil morphology was not statistically different from that before surgery (pupil morphology: χ2=0.131; P=0.717); however, the pupillary light reflex was significantly improved after surgery (χ2=8.378; P=0.004), and the pupil diameter was significantly increased (T=−3.494; P=0.003). The rate of corneal endothelial cell loss was higher in small pupil group than in the normal pupil group in the 3rd postoperative month, but the difference was not statistically significant (T=−0.023; P=0.982).ConclusionsThe prechop technique using a reverse chopper in small-pupil cataract surgery occupies a similar operative time, cumulative energy consumption during operation, BVCA, pupil morphology, and rate of corneal endothelial cell loss, comparing with those in normal-pupil cataract surgery. To such a degree, it is a safe, high-efficiency, a simple and easy-to-operate nucleus-chopping technique that can be used in small-pupil cataract surgery.

Aggregation of Demand-Side Flexibility in Electricity Markets: Negative Impact Analysis and Mitigation Method

Aggregation of demand-side flexibility plays a crucial role in helping improve the system-wide performance of power grids. However, little considered is the potential negative impact of self-interested flexibility aggregators, who are being strategic for their own benefit at the cost of other market participants or even system-wide performance. This article aims to theoretically analyze this negative impact, as well as propose a corresponding mitigation method. Specifically, we consider a strategic aggregator that derives the optimal bidding strategy of the flexibility bounds (for cumulative energy and instantaneous power consumption) and trades electricity in a pool. A multi-period bi-level program with a DC network setup is considered. The upper-level problem represents the aggregator's cost minimization, and the lower-level problem represents the market clearing process. Based on this bi-level formulation, our theoretical analysis shows that the potential negative impact of the strategic behavior on the system generation cost, the payment of the fixed loads, and the payment of the non-strategic aggregators depends on the bus locations of both the strategic and non-strategic aggregators. We propose to additionally charge the strategic aggregator for the newly introduced congestion so as to avoid system performance degradation. The analytical results are validated via simulations.

Exploring the distribution of energy consumption in a northeast Chinese city based on local climate zone scheme: Shenyang city as a case study

The local climate zone (LCZ) scheme is now used to investigate urban heat islands, which provides additional reference for energy consumption simulation. Based on the LCZ scheme, a LCZ mapping of Shenyang, a city in northeast China, was first constructed using the World Urban Database and Access Portal Tools (WUDAPT) Level 0 method. Subsequently, DeST-h was considered to simulate the energy consumption of urban buildings with concentration areas. The results show that with Shenyang being a severely cold area, the annual energy consumption of heating is approximately twice that of refrigeration for an individual building. The total energy consumption of open-distributed single buildings is higher than that of compact-distributed single buildings. Consequently, the unit cumulative energy consumption in compact-distributed buildings is higher than that in openly distributed building areas. The compact high-rise buildings (LCZ 1) have the highest energy consumption, with a unit annual energy consumption of 123,771.150 MW·h, which is equivalent to 41,257 tons of standard coal combustion power generation. Considering the energy consumption of residential buildings, the central high-rise buildings group and the compact centralized middle-rise buildings in the downtown area are high energy consumption areas. For future urban planning, design strategies such as energy-saving transformation and energy planning should be considered. The research results can provide a scientific basis and theoretical support for reducing building energy consumption, alleviating the urban heat island effect, and the development of modern urban planning.

Behavior of geopolymeric recycled aggregate concrete-filled FRP tube (GRACFFT) columns under lateral cyclic loading

In order to improve the environmental sustainability of concrete-filled FRP (fibre-reinforced plastic) tube (CFFT) column, a new kind of composite column, geopolymeric recycled aggregate concrete-filled FRP tube (GRACFFT) column, was proposed in this paper. The hysteretic behaviors of GRACFFT columns were experimentally investigated. The influences of different parameters, i.e., fiber types, section form, and reinforcement type were discussed. Based on the strain analysis, the plastic hinge length and utilization factor of FRP fibers for each GRACFFT column were also investigated. According to the experimental results, it was found that the proposed GRACFFT column showed favorable seismic performance with both high carrying capacity and deformation ability. The proposed GRACFFT column made with carbon FRP tube showed the best seismic behaviors in terms of yield displacement, peak load, ultimate displacement, and cumulative energy consumption. In terms of cross-section, the seismic behaviors of the circular GRACFFT column were better than that of the square column. Also, it was found that the substitution of steel reinforcements with steel tube could effectively increase the seismic behaviors of GRACFFT columns.

Joint optimization of delay-recovery and energy-saving in a metro system: A case study from China

Reducing delays in the metro transit system improves passenger satisfaction and the operational efficiency of the system. However, current delay-recovery strategies tend to reduce delays rather than the operational costs of the metro company. We propose optimized delay-recovery strategies to reduce the delay and increase energy efficiency simultaneously in this study. We classified delays in historical data according to the relationship between the delay time and the following headway, and we present optimized delay-recovery strategies for different initial delay conditions. A multi-objective optimization model was used to minimize the cumulative delay time (CDT) and energy consumption. We added weight factors to the objective functions to reflect the preferences of decision-makers regarding delay recovery and energy savings. We applied the non-dominated sorting genetic algorithm-II (NSGA-II) to solve the proposed model and verified its performance using a case study of the Chengdu Metro. The results showed that the proposed model exhibited excellent performance regarding delay recovery and energy savings.

Double-feedback control with stepless variable speed driving technology by sensing refrigerant pressure and indoor temperature applied to air conditioning system

An energy-saving strategy of variable refrigerant volume (VRV) is proposed for air conditioning systems by using the stepless variable speed driving technology. This control technology is applied to the air cooled packaged water chiller unit (ACH) according to the change of environmental heat load to achieve the best amount of refrigerant in real time. This study designs a double feedback Stepless Variable Frequency and Variable Refrigerant Output (DFSVFVRO) for controlling ACH. The double feedback variable frequency control uses both temperature and the pressure sensors as feedback signals to the control board and the frequency of the compressor is regulated by the inverter. Experimental results indicate that the proposed variable frequency control method has a lower energy consumption compared with the conventional normal mode (N). In addition, the proposed double feedback mode (DF) has a lower energy consumption, and thus, it is with better energy efficiency. Furthermore, in the various experiments of proposed DFSVFVRO by comparing the cumulative energy consumption of DF mode with N mode, the DF mode shows an energy saving rate of at least 25%. It also verifies that the double feedback variable frequency control method has a better energy-saving benefits than that of the single feedback frequency.

Dynamic Trends of Fine Particulate Matter Exposure across 190 Countries: Analysis and Key Insights

Despite the fact that fine particulate matter (PM2.5) causes serious health issues, few studies have investigated the level and annual rate of PM2.5 change across a large number of countries. For a better understanding of the global trend of PM2.5, this study classified 190 countries into groups showing different trends of PM2.5 change during the 2000–2014 period by estimating the progress ratio (PR) from the experience curve (EC), with PM2.5 exposure (PME)–the population-weighted average annual concentration of PM2.5 to which a person is exposed—as the dependent variable and the cumulative energy consumption as the independent variable. The results showed a wide variation of PRs across countries: While the average PR for 190 countries was 96.5%, indicating only a moderate decreasing PME trend of 3.5% for each doubling of the cumulative energy consumption, a majority of 118 countries experienced a decreasing trend of PME with an average PR of 88.1%, and the remaining 72 countries displayed an increasing trend with an average PR of 110.4%. When two different types of EC, classical and kinked, were applied, the chances of possible improvement in the future PME could be suggested in the descending order as follows: (1) the 60 countries with an increasing classical slope; (2) the 12 countries with an increasing kinked slope; (3) the 75 countries with a decreasing classical slope; and (4) the 43 countries with a decreasing kinked slope. The reason is that both increasing classical and kinked slopes are more likely to be replaced by decreasing kinked slopes, while decreasing classical and kinked slopes are less likely to change in the future. Population size seems to play a role: A majority of 52%, or 38 out of the 72 countries with an increasing slope, had a population size of bigger than 10 million inhabitants. Many of these countries came from SSA, EAP, and LAC regions. By identifying different patterns of past trends based on the analysis of PME for individual countries, this study suggests a possible change of the future slope for different groups of countries.

Experimental study and numerical simulation of reinforced concrete walls with lightened blocks connected with bolts

To verify the feasibility and mechanical properties of assembled composite walls, three assembled composite walls were designed. Two bolted connection specimens in horizontal joints were tested under low-cycle reversed loading and monotonic loading, respectively. Then, the failure mechanism, hysteretic behaviour, ductility, energy dissipation capacity, slip and stress distribution of the connectors were studied. A specimen with grouting sleeve connection was tested under low-cycle reversed loading as a contrast specimen. In addition, a specimen with bolted connection under monotonic loading was simulated by the finite element method to study the effects on structural performance of the connectors and walls. The results show that the bolted connection is feasible, and compared with the grouting sleeve connection, the bearing capacity of the bolted connection specimen decreases by 17%, the displacement ductility coefficient increases by 52% and the cumulative energy consumption increases by 62%. Slippage between the connectors and the wallboard occurs mainly between the yield point and the peak point of the specimens. With the increase in plate thickness, the bearing capacity and initial stiffness increased, but there was no obvious effect on the appearance of the slip section. The larger the bolt diameter, the later the slip section forms. However, the bolt diameter does not have an obvious effect on the bearing capacity of the specimens.

Coverage and Energy Analysis of Mobile Sensor Nodes in Obstructed Noisy Indoor Environment: A Voronoi-Approach

When deploying a wireless sensor network (WSN) identifying optimal locations for the nodes is challenging, especially so if the environment is either (i) unknown or (ii) obstacle-rich. We proposes BISON (Bio-Inspired Self-Organizing Network), a variant of the Voronoi algorithm to address this challenge. Among the features of the approach are the restrictions placed upon the abilities of the nodes: (i) all information is sensed locally as well as (ii) subject to communication noise. Performance is measured as (i) the percentage of area covered, (ii) the total distance traveled by the nodes, (iii) the cumulative energy consumption and (iv) the uniformity of nodes’ distribution. Obstacle constellations and noise levels are studied systematically and a collision-free recovery strategy for failing nodes is proposed. Results obtained from extensive simulations show the algorithm outperforming previously reported approaches in both, convergence speed, as well as deployment cost.

Heuristic approach to minimise the energy consumption of sensors in cloud environment for wireless body area network applications

The wireless sensor networks are single user centric and end users who do not own sensors are unable to have access to any wireless network specific application. This sensor cloud is a new paradigm to manage the physical sensors which are deployed in any WSN application. Existing research work on sensor cloud is limited to guaranteeing minimal energy consumption. In this paper, a novel mathematical model based on virtual sensor grouping is proposed to minimise the cumulative energy consumption of sensors in cloud environment. Energy consumption of non-virtual sensor with virtual sensor group for two different applications is compared and the results are shown. Further the proposed sensor cloud infrastructure with power model is compared with traditional WSN with respect to energy efficiency, throughput and performance with quick synchronisation time for random run trials and results were found to be better than the conventional WSN.

Winners from the changing trends of energy intensities among 115 countries

Many countries in the world have been experiencing vastly different rates of changes in their energy intensity (EI). The rate of change in EI for each country was estimated from the progress ratio (PR) of experience curve (EC). We ranked all 115 countries according to their PRs. The averaged PR of 90.21% estimated for the total 115 countries indicates a globally decreasing trend of EI. This means that each doubling of cumulative energy consumption has reduced energy intensity by 9.79%. On the other hand, 40 countries have experienced an increasing trend with an average PR of 119.41%. When two different types of EC, classical and kinked, were used, 81 countries displayed a kinked slope with an average PR of 84.98%. Analysing both the type of trend and slope of EC indicates that as many as 70 countries may have the best or better chances to improve their PRs in the future Implications from these findings will be discussed.

Winners from the changing trends of energy intensities among 115 countries

Many countries in the world have been experiencing vastly different rates of changes in their energy intensity (EI). The rate of change in EI for each country was estimated from the progress ratio (PR) of experience curve (EC). We ranked all 115 countries according to their PRs. The averaged PR of 90.21% estimated for the total 115 countries indicates a globally decreasing trend of EI. This means that each doubling of cumulative energy consumption has reduced energy intensity by 9.79%. On the other hand, 40 countries have experienced an increasing trend with an average PR of 119.41%. When two different types of EC, classical and kinked, were used, 81 countries displayed a kinked slope with an average PR of 84.98%. Analysing both the type of trend and slope of EC indicates that as many as 70 countries may have the best or better chances to improve their PRs in the future Implications from these findings will be discussed.

Securing Cloud Framework from Application DDoS Attacks

With the extensive growth of in the size of data transmitted and received in the cloud, there arises the risk of sensitive data prone to different kinds of attacks. The attacks may be in the form of intrusions trying to hack the data or in the form of some fatal attacks. To focus more, after the extensive use of applications and social media apps, there is a rise in Application DDoS (Distributed Denial-of-Service) attacks. These attacks are called as L7 (Layer 7) of the OSI Reference model, as they target the topmost layer – the Application Layer. Various simulations in the Cloud have concluded that the cumulative energy consumption and huge amount of migrations on the VMs are severely affected by the Application DDoS attacks or the EDoS (Economic Denial of Sustainability) attacks. This paper discusses the various forms of Application DDoS attacks, the mitigation mechanisms for the Application DDoS attacks and compares the results in the simulated cloud environment.