Unbalanced Energy Research Articles

Long-term power-to-gas potential from wind and solar power: A country analysis for Italy

Challenges related to variability of renewable energy sources (RES) recently arose in many countries and several solutions based on energy storage were proposed; among them, a promising option is Power-to-Gas (P2G), able to recover excess and unbalanced electrical energy. In this work, an assessment of long-term P2G potential is performed on a country scale, based on the analysis of electrical system historical data series, rescaled in order to consider the evolution of load and installed wind and solar capacity. In a long-term perspective, it is assumed the complete exploitation of the technical potential of the RES, which represents an upper deployment boundary with current technology. Once satisfied the electric load, residual energy to the P2G system and hydrogen production are calculated on a hourly basis; P2G installed capacity is a consequence of the assumed target on minimum operation on a yearly basis. The Italian case is analyzed, evidencing that the recovered excess energy from RES could substitute nearly 5% of current natural gas consumption or about 7% of national fuel consumption when used for hydrogen mobility. A range of options and a sensitivity analysis on assumptions is presented, showing scenarios with up to 200 GW of installed RES and a 50% additional load with respect to current one. In addition, the extension of the model to a zonal grid structure evidences the impact of transmission lines saturation that may increase gas production up to 50%. Results are compared with the German case, considered in a previous work, evidencing differences due to the diverse energy production mix.

Energy balance and obesity: what are the main drivers?

PurposeThe aim of this paper is to review the evidence of the association between energy balance and obesity.MethodsIn December 2015, the International Agency for Research on Cancer (IARC), Lyon, France convened a Working Group of international experts to review the evidence regarding energy balance and obesity, with a focus on Low and Middle Income Countries (LMIC).ResultsThe global epidemic of obesity and the double burden, in LMICs, of malnutrition (coexistence of undernutrition and overnutrition) are both related to poor quality diet and unbalanced energy intake. Dietary patterns consistent with a traditional Mediterranean diet and other measures of diet quality can contribute to long-term weight control. Limiting consumption of sugar-sweetened beverages has a particularly important role in weight control. Genetic factors alone cannot explain the global epidemic of obesity. However, genetic, epigenetic factors and the microbiota could influence individual responses to diet and physical activity.ConclusionEnergy intake that exceeds energy expenditure is the main driver of weight gain. The quality of the diet may exert its effect on energy balance through complex hormonal and neurological pathways that influence satiety and possibly through other mechanisms. The food environment, marketing of unhealthy foods and urbanization, and reduction in sedentary behaviors and physical activity play important roles. Most of the evidence comes from High Income Countries and more research is needed in LMICs.

Dynamic clustering and management of mobile wireless sensor networks

In Wireless Sensor Networks (WSNs), routing data towards the sink leads to unbalanced energy consumption among intermediate nodes resulting in high data loss rate. The use of multiple Mobile Data Collectors (MDCs) has been proposed in the literature to mitigate such problems. MDCs help to achieve uniform energy-consumption across the network, fill coverage gaps, and reduce end-to-end communication delays, amongst others. However, mechanisms to support MDCs such as location advertisement and route maintenance introduce significant overhead in terms of energy consumption and packet delays. In this paper, we propose a self-organizing and adaptive Dynamic Clustering (DCMDC) solution to maintain MDC-relay networks. This solution is based on dividing the network into well-delimited clusters called Service Zones (SZs). Localizing mobility management traffic to a SZ reduces signaling overhead, route setup delay and bandwidth utilization. Network clustering also helps to achieve scalability and load balancing. Smaller network clusters make buffer overflows and energy depletion less of a problem. These performance gains are expected to support achieving higher information completeness and availability as well as maximizing the network lifetime. Moreover, maintaining continuous connectivity between the MDC and sensor nodes increases information availability and validity. Performance experiments show that DCMDC outperforms its rival in the literature. Besides the improved quality of information, the proposed approach improves the packet delivery ratio by up to 10%, end-to-end delay by up to 15%, energy consumption by up to 53%, energy balancing by up to 51%, and prolongs the network lifetime by up to 53%.

Congestion control and energy‐balanced scheme based on the hierarchy for WSNs

The problem of congestion control with balanced-energy is important for application of WSNs, since the limited resources and many-to-one communication model often result in congestion and unbalanced energy consumption. In this study, a hierarchy-based congestion control and energy-balanced scheme is proposed. The network model is firstly initialised into a hierarchical topology, by which these neighbour nodes of a node will be explicitly divided into three kinds, i.e., the same hierarchical nodes, the upstream nodes, and the downstream nodes. Then, in the proposed congestion avoidance method, the node will use other lower hierarchy neighbour nodes to forward data when its downstream node will be congested. After that, the congestion control mechanism will detect the congestion via the queue length, forwarding and receiving rate, and inform its upstream nodes to find other next hop to release the congestion. The balanced energy consumption strategy will balance the energy consumption of lower hierarchy nodes by using the node with the most remaining energy. Meanwhile, by using the same hierarchy nodes, the remaining energy of all the nodes in the same hierarchy is balanced. Simulation results show that the proposed algorithm can effectively deal with the network congestion and unbalanced energy consumption.

An Enhanced Energy Efficiency Tree-Based Hierarchical Routing Based on Additional Connections

Instrumented is defined as a key characteristic in the upcoming smart cites, which demands a higher Wireless Sensor Networks (WSNs) performance. Tree-based Hierarchical Routing (THR) is a routing protocol for WSNs static scenarios. THR hierarchically maps WSN area into a routing tree. However, fixed topology and hierarchical architecture leads to unbalanced energy overhead distribution and inflexible routes selection. To uniformly distribute routing energy overhead, reduce routing hops and extend network life cycle, we designed an enhanced THR routing protocol based on additional connections such as Neighbors, Brothers and Nephews. Based on these connections, three actions were introduced which are Shortcut, Overhead Balancing and Adoption. A simulation for different network loads on OMNet++4.1 is issued, and realized this THR routing in Chipcon SmartRF04?EB embedded boards based on Zigbee in a point-to-point topology. According to the simulation results and experiment data, this proposal obviously improved the latency performance, reduced energy overhead and extended the network’s life cycle.

Routing-Gi: Routing technique to enhance energy e?ceincy in WSNs

Wireless sensors networks (WSNs) are realised as one of the most promising networking types that bridge the gap between the cyber and the things. Designing of routing protocols for WSNs is a challenging issue since sensors are mostly limited in energy and data processing. In this paper, we present a new routing technique for hierarchical routing protocols to enhance energy efficiency in WSNs, namely Routing-Gi. This technique divides network area into the inner grid and clustered grids. In an inner grid, the nodes transmit directly data to the base station (BS), whereas, in clustered grid, the nodes are organised into micro-grids and thus each node transmits data to the BS through it respective cluster head. in this case, the micro-grids help to avoid unbalanced energy consumption in WSNs. Thus, the workload is evenly distributed on nodes causing the efficient energy of network to enhance. The simulation results prove the effectiveness of our technique.

Balanced Load Distribution With Energy Hole Avoidance in Underwater WSNs

Due to limited energy resources, energy balancing becomes an appealing requirement/challenge in Underwater Wireless Sensor Networks (UWSNs). In this paper, we present a Balanced Load Distribution (BLOAD) scheme to avoid energy holes created due to unbalanced energy consumption in UWSNs. Our proposed scheme prolongs the stability period and lifetime of the UWSNs. In BLOAD scheme, data (generated plus received) of underwater sensor nodes is divided into fractions. The transmission range of each sensor node is logically adjusted for evenly distributing the data fractions among the next hop neighbor nodes. Another distinct feature of BLOAD scheme is that each sensor node in the network sends a fraction of data directly to the sink by adjusting its transmission range and continuously reports data to the sink till its death even if an energy hole is created in its next hop region. We implement the BLOAD scheme, by varying the fractions of data using adjustable transmission ranges in homogeneous and heterogeneous simulation environments. Simulation results show that the BLOAD scheme outperforms the selected existing schemes in terms of stability period and network lifetime.

Data Collection Strategy in Low Duty Cycle Wireless Sensor Networks with Mobile Sink

The lifetime of wireless sensor networks can be improved by imposing low duty cycle, but doing so could not solve unbalanced energy consumption and will increase transmission latency. To avoid this, this paper gives a new method to collect data by mobile sink. The proper data collection route is selected according to the sink speed and buffer size of the sensors. The sensors only wake up when the sink approaches them. When certain sensors detect an emergency, the sink catches the message quickly and moves to the hotspot to decrease message relay in the network. The result of simulation by OPNET shows that this protocol can reduce transmission data in the network and prolong the network lifetime.

지하수류가 밀폐형 천공 지중 열교환기 성능에 미치는 영향(2)

An increase of groundwater flux in BHE system creates that ground temperature (locT) becomes lower in summer and higher in winter time. In other words, it improves significantly the performance of BHE system. The size of thermal plume made up by advection driven-flow under the balanced energy load is relatively small in contrast to the unbalanced energy load where groundwater flow causes considerable change in the size of thermal plume as well ground temperature. The ground temperatures of the up gradient and down gradient BHEs under conduction only heat transport are same due to no groundwater flow. But a significant difference of the ground temperature is observed between the down gradient and up gradient BHE as a result of groundwater flow-driven thermal interference took placed in BHE field. As many BHEs are designed under the obscure assumption of negligible groundwater flow, failure to account for advection can cause inefficiencies in system design and operation. Therefore including groundwater flow in the design procedure is considered to be essential for thermal and economic sustain ability of the BHE system.

Entanglement is a costly life-history stage in large whales.

Individuals store energy to balance deficits in natural cycles; however, unnatural events can also lead to unbalanced energy budgets. Entanglement in fishing gear is one example of an unnatural but relatively common circumstance that imposes energetic demands of a similar order of magnitude and duration of life‐history events such as migration and pregnancy in large whales. We present two complementary bioenergetic approaches to estimate the energy associated with entanglement in North Atlantic right whales, and compare these estimates to the natural energetic life history of individual whales. Differences in measured blubber thicknesses and estimated blubber volumes between normal and entangled, emaciated whales indicate between 7.4 × 1010 J and 1.2 × 1011 J of energy are consumed during the course to death of a lethal entanglement. Increased thrust power requirements to overcome drag forces suggest that when entangled, whales require 3.95 × 109 to 4.08 × 1010 J more energy to swim. Individuals who died from their entanglements performed significantly more work (energy expenditure × time) than those that survived; entanglement duration is therefore critical in determining whales’ survival. Significant sublethal energetic impacts also occur, especially in reproductive females. Drag from fishing gear contributes up to 8% of the 4‐year female reproductive energy budget, delaying time of energetic equilibrium (to restore energy lost by a particular entanglement) for reproduction by months to years. In certain populations, chronic entanglement in fishing gear can be viewed as a costly unnatural life‐history stage, rather than a rare or short‐term incident.

Rotating stratified turbulence and the slow manifold

Abstract Numerical simulations of decaying rotating stratified turbulence were performed from balanced initial conditions using the Baer–Tribbia initialisation scheme as an approximate projection onto the slow manifold of the non-hydrostatic Boussinesq equations. Starting with the low Rossby and Froude numbers characterising the quasigeostrophic limit, these were increased somewhat until small-scale balance appeared to break down. Following a previous paper by the authors, this occurred in conjunction with the emergence of a shallow range in the energy spectrum. The goal here is to work towards identifying the mechanism and characteristic scales of the resulting spontaneous imbalance. It is found that it originates at relatively large scales near the low-wave number end of the shallow spectral range. Unbalanced energy then cascades to small scales where it is efficiently dissipated in the decay case. The predominant interaction over the shallow range was seen to be a downscale cascade of unbalanced energy with little interaction with the balanced flow. At even smaller scales the decomposition loses its meaning and the spectrum remains shallow.

An adaptive energy balanced and energy efficient approach for data gathering in wireless sensor networks

Energy efficiency and energy balancing are the most stringent needs of wireless sensor network for prolonging its lifetime. As direct transmissions are costly, multi-hop approach is often used to collect the data of the nodes at the sink. However, many-to-one communication pattern in multi-hop communication may result in an unbalanced energy consumption in the network. Nodes closer to the sink deplete their energy at a faster rate than nodes that are further away. Mixed transmission approach, where each node trades-off between the cheaper hop-by-hop transmission and costlier direct transmission, is a good solution for balancing energy consumption. This paper proposes a receiver contention based mixed transmission scheme for energy balancing. In addition to distance and residual energy of the receivers, it also considers the link reliability and the number of neighboring nodes, in setting of the timer that will determine the relay node selection. The proposed approach gives more efficient and effective energy balanced data transmission as compared with the other works proposed in the literature. Its performance is evaluated and presented both analytically and through simulations, and the analytical estimations are validated by the simulation results. The simulation results show a significant improvement over the other closely related approaches. Moreover, the proposed approach can be easily used with both uniform as well as non-uniform node deployment.

Data gathering problem with the data importance consideration in Underwater Wireless Sensor Networks

In Underwater Wireless Sensor Networks (UWSNs), if sensors rely on multi-hop transmission to send sensing data to the sink above the water, sensors that are closer to the water's surface will deplete energy sooner because they share a larger load of the packet relaying work. This problem becomes worse if the water being monitored is very deep. This imbalance in energy consumption can be effectively mitigated by using an Autonomous Underwater Vehicle (AUV) to collect data. However, if the data to collect are important, the delay time required by this data gathering method may be too long. In this study, we integrate the two data gathering mechanisms mentioned above, namely utilization of AUVs and multi-hop transmission, to reduce the problem of unbalanced energy consumption and long delay time. Moreover, we also investigate how to determine the importance level of data and set delay time requirements without domain knowledge. Our purpose is to deliver data of higher importance to the sink within the delay time requirement. Our experimental results confirm that the proposed method can effectively mitigate the imbalance in energy consumption, reduce the delay time required for delivering important data, and also prolong the network lifetime.

Energy aware hierarchical cluster-based routing protocol for WSNs

Wireless sensor networks (WSNs) are emerging as essential and popular ways of providing pervasive computing environments for various applications. Unbalanced energy consumption is an inherent problem in WSNs, characterized by multi-hop routing and a many-to-one traffic pattern. This uneven energy dissipation can significantly reduce network lifetime. In multi-hop sensor networks, information obtained by the monitoring nodes need to be routed to the sinks, the energy consumption rate per unit information transmission depends on the choice of the next hop node. In an energy-aware routing approach, most proposed algorithms aim at minimizing the total energy consumption or maximizing network lifetime. In this paper, we propose a novel energy aware hierarchical cluster-based (NEAHC) routing protocol with two goals: minimizing the total energy consumption and ensuring fairness of energy consumption between nodes. We model the relay node choosing problem as a nonlinear programming problem and use the property of convex function to find the optimal solution. We also evaluate the proposed algorithm via simulations at the end of this paper.

Energy efficient social routing framework for mobile social sensing networks

Mobile social sensing network is one kind of emerging networks in which sensing tasks are performed by mobile users and sensing data are shared and collected by leveraging the intermittent inter-contacts among mobile users. Traditional ad hoc routing protocols are inapplicable or perform poorly for data collection or data sharing in such mobile social networks because nodes are seldom fully connected. In recent years, many routing protocols (especially social-based routing) are proposed to improve the delivery ratio in mobile social networks, but most of them do not consider the load of nodes thus may lead to unbalanced energy consumption among nodes. In this paper, we propose a simple Energy Efficient framework for Social-based Routing (EE-SR) in mobile social sensing networks to balance the load of nodes while maintaining the delivery ratio within an acceptable range by limiting the chances of forwarding in traditional social-based routing. Furthermore, we also propose an improved version of EE-SR to dynamically adjust the controlling parameter. Simulation results on real-life mobile traces demonstrate the efficiency of our proposed framework.

지하수류가 밀폐형 천공 지중열교환기 성능에 미치는 영향(1)

To analyze the influence of various groundwater flow rates (specific discharge) on BHE system with balanced and unbalanced energy loads under assuming same initial temperature (15℃) of ground and groundwater, numerical modeling using FEFLOW was used for this study. When groundwater flow is increased from 1 × 10^−7 to 4 × 10^−7m/s under balanced energy load, the performance of BHE system is improved about 26.7% in summer and 22.7% at winter time in a single BHE case as well as about 12.0~18.6% in summer and 7.6~8.7% in winter time depending on the number of boreholes in the grid, their array type, and bore hole separation in multiple BHE system case. In other words, the performance of BHE system is improved due to lower avT in summer and higher avT in winter time when groundwater flow becomes larger. On the contrary it is decreased owing to higher avT in summer and lower avT in winter time when the numbers of BHEs in an array are increased, Geothermal plume created at down-gradient area by groundwater flow is relatively small in balanced load condition while quite large in unbalanced load condition. Groundwater flow enhances in general the thermal efficiency by transferring heat away from the BHEs. Therefore it is highly required to obtain and to use adequate informations on hydrogeologic characterristics (K, S, hydraulic gradient, seasonal variation of groundwater temperature and water level) along with integrating groundwater flow and also hydrogeothermal properties (thermal conductivity, seasonal variation of ground temperatures etc.) of the relevant area for achieving the optimal design of BHE system.

Resource aware and reliable data reporting algorithm for object tracking in WSNs

Object tracking have become one of the major applications of Wireless Sensor Networks (WSNs) due to its wide real-life applications such as wildlife animal monitoring and military area intrusion detection. Many recent articles have been dedicated to localization of objects; however, few of these ar ticles were concentrated on the reliability of network data reporting along with objects localization. In this work, an efficient data reporting method is proposed for object tracking in WSNs. Energy is considered as one of the most critical resources for WSN. Data transmission from the nodes to the sink along with the minimum energy path could be one of the solutions to minimize the overall network energy consumption. However, this might lead to unbalanced energy among sensor nodes resulting in, energy hole problem. Moreover, the reliable data transmission is an essential aspect that should be considered when designing a WSN for object tracking application, where the loss of data packets will affect the accuracy of the tracking and location estimation of a mobile object. Furthermore, due to the limited memory resources of sensor nodes, full utilization of such resources with less buffer overflow remains as a one of main consideration when a WSN application is designed. Consequently, this paper aims to achieve both minimum energy consumption in reporting operation and balanced energy consumption among sensor nodes for WSN lifetime extension. In addition, data reliability is considered in our model where, the sensed data can reach the sink node in a more reliable way. Finally, buffer space is considered in to reduce the packet loss and energy consumption due to the retransmission of the same packets. This work first formulates the problem as 0/1 Integer Linear Programming (ILP) problem, and proposes SWARM intelligence to solve the optimization problem. Through simulation, the performance of proposed method to report information about the detected objects to the sink is compared with the previous work such as LR-based object tracking algorithm, EBRP, ACO, TADR, SEB, and CLR-Routing.

A Location-Wise Predetermined Deployment for Optimizing Lifetime in Visual Sensor Networks

Visual sensor networks are receiving significant attention due to their potential applications ranging from surveillance to tracking domains. Nevertheless, due to the funneling effect, the unbalanced energy usage among visual sensor nodes (SNs) increases and leads to premature decrease in network lifetime. First, considering Rayleigh fading channel and routing models, we analyze the optimization of network lifetime by balancing the energy consumption among different SNs. From the analysis, it is revealed that the number of SNs and relay nodes and their locations have significant influence on limiting the energy hole problem and optimization of network lifetime. Based on the derived principle of energy balancing, we develop a heterogeneous SNs deployment strategy leading to optimization in network lifetime. Exhaustive simulation is performed, primarily to measure the extent of achieving our design goal of optimizing network lifetime while attaining energy balancing. We also measure the effect of placement errors on the performance and robustness of the scheme. The results show that even in the presence of placement error the performance is comparable and provides better robustness compared with the competing scheme. Further, the simulation results show that our scheme does not compromise with other performance metrics, e.g., end-to-end delay and throughput, while achieving the design goal. Finally, all the comparative results confirm our scheme’s supremacy over the competing schemes.

A Network Access Mechanism for Multihop Underwater Acoustic Local Area Networks

Multihop underwater acoustic local area networks (MUA-LANs), which can greatly improve the access ability of underwater networks, suffer from the lack of network access mechanism utilized by new nodes to join the networks. Existing network access mechanisms for terrestrial wireless LANs cannot be directly applied to MUA-LANs due to the multihop topologies of MUA-LANs and the acoustic channel features of limited bandwidth and high propagation delay. In this paper, we present a network access mechanism constituted by three phases of network discovery, relay path determining, and association for MUA-LANs. The basic idea of our network access mechanism is to let the nodes that have joined a network assist new nodes in accessing the network by multihop relay forwarding. We theoretically verify that the unbalanced energy consumption is serious in MUA-LANs. Therefore, we present a lifetime and energy efficiency-based relay path selection algorithm in relay path determining phase. This algorithm can significantly prolong the network lifetime and improve energy efficiency. In association phase, we employ a MAC address forwarding tables mechanism. By utilizing this mechanism, multihop relay forwarding can be realized easily. The simulation results have confirmed that the proposed network access mechanism can achieve excellent performance owing to the lifetime and energy efficiency-based relay path selection algorithm and the MAC address forwarding tables mechanism.

Fuzzy Logic Approach to Zone-Based Stable Cluster Head Election Protocol-Enhanced for Wireless Sensor Networks

Energy is a scarce resource in wireless sensor networks (WSNs). A variety of clustering protocols for WSNs, such as the zone-based stable election protocol-enhanced (ZSEP-E), have been developed for energy optimization. The ZSEP-E is a heterogeneous zone-based clustering protocol that focuses on unbalanced energy consumption with parallel formation of clusters in zones and election of cluster heads (CHs). Most ZSEP-E research has assumed probabilistic election of CHs in the zones by considering the maximum residual energy of nodes. However, studies of the diverse CH election parameters are lacking. We investigated the performance of the ZSEP-E in such scenarios using a fuzzy logic approach based on three descriptors, i.e., energy, density, and the distance from the node to the base station. We proposed an efficient ZSEP-E scheme to adapt and elect CHs in zones using fuzzy variables and evaluated its performance for different energy levels in the zones.