Sink Location Research Articles

An efficient placement of sinks and SDN controller nodes for optimizing the design cost of industrial IoT systems

SummaryRecently, a growing trend has emerged toward using Internet of Things (IoT) in the context of industrial systems, which is referred to as industrial IoT. To deal with the time‐critical requirements of industrial applications, it is necessary to consider reliability and timeliness during the design of an industrial IoT system. Through the separation of the control plane and the data plane, software‐defined networking provides control units (controllers) coexisting with sink nodes, efficiently coping with network dynamics during run‐time. It is of paramount importance to select a proper number of these devices (i.e., software‐defined networking controllers and sink nodes) and locate them wisely in a network to reduce deployment cost. In this paper, we optimize the type and location of sinks and controllers in the network, subject to reliability and timeliness as the prominent performance requirements in time‐critical IoT systems through ensuring that each sensor node is covered by a certain number of sinks and controllers. We propose PACSA‐MSCP, an algorithm hybridizing a parallel version of the max‐min ant system with simulated annealing for multiple‐sink/controller placement. We evaluate the proposed algorithm through extensive experiments. The performance is compared against several well‐known methods, and it is shown that our approach outperforms those methods by lowering the total deployment cost by up to 19%. Moreover, the deviation from the optimal solution achieved by CPLEX is shown to be less than 2.7%.

A virtual grid-based real-time data collection algorithm for industrial wireless sensor networks

Industrial wireless sensor networks (IWSNs) have been widely used in many application scenarios, and data collection is an extremely significant part of IWSNs. Moreover, a mobile sink is widely used in industrial wireless sensor networks to collect sensory data and alleviate the “hot spot” problem effectively. However, usage of a mobile sink introduces some challenges, such as updating of a mobile sink’s location and planning of a mobile sink’s trajectory. Meanwhile, the impact of different distribution types of events on data collection has not been sufficiently valued in designing of data collection algorithm for IWSNs yet. To overcome these challenges, a virtual grid-based real-time data collection algorithm for applications with centrally distributed events (VGDCA-C) is proposed in this paper to gain a reliable data gathering for IWSNs. In the target application scenarios, the events are distributed centrally, so we mainly focus on how to shorten the routing paths and decrease the transmission delay. In our VGDCA-C, a mobile sink can adjust its movement dynamically according to the changes in event areas. The adjustment of a mobile sink movement strategy includes two aspects. The first one is the dynamic adjustment of a mobile sink’s parking time, and the second one denotes the moving toward event area of a mobile sink. Thus, a mobile sink adjusts its location such that it can get closer to the event area. Hence, the total length of routing is getting shorter so that source nodes can upload sensory data faster. Analysis and simulation results show that compared with the existing work, our VGDCA-C increases the network lifetime and decreases transmission delay.

Layout Design of Conductive Heat Channel by Emulating Natural Branch Systems

To design effective and easy-to-manufacture conductive heat channels, a heuristic method by emulating the natural branch systems is suggested. The design process of the method is divided into two steps, which are the principal channel design and the lateral channel design. During the process, the width of each channel is controlled by the bifurcation law, and the end point of the channel is located at the point with the maximum temperature while the start points of the principal channel and the lateral channel are respectively determined by the location of the heat sink and the law of the minimum thermal resistance. Four design examples with different boundary conditions are studied by the suggested method, and the design results are compared with that of the traditional structural topology optimization method. Not only lower maximum temperature and relatively uniform distribution of temperature are obtained by the suggested method, but also straight channels are achieved without gray element, which is easy to manufacture. The suggested method inspired by the natural branch systems can provide an effective solution for heat channel design in the heat dissipation structures.

Arc-Malstrøm: A 1D hydrologic screening method for stormwater assessments based on geometric networks

A method is presented to perform a first screening of high-resolution digital terrain models to detect the extents and capacities of local landscape sinks. When identified their capacities and rain volumes provided from their local catchments during a rainstorm are saved as attributes for the pour points. Next, the downstream paths from the pour points are saved as junctions and edges in a geometric network leading to a final calculation of the accumulated spillover in the topologic data structure determined by a custom trace tool. Although the screening method is based on a representation of the overland surface in a 1D network not involving any hydrodynamic components, it is well suited to provide a quick first overview of a landscape's overall drainage basins, the location of sinks, their contributing watersheds and the accumulated downstream flow when the sinks spill over. The exemplified study assumes Hortonian flow and a uniform rain event, but if spatial variations in precipitation or infiltration capacities are available the local sinks' catchment level, they may easily be added to the workflow to produce first risk map approximations for residential areas threatened by future stormwater incidents.

Effect of sink location and redundancy on multi‐sink wireless sensor networks: a capacity and delay analysis

Wireless network applications such as intelligent buildings and disaster relief operations use large-scale platforms. In these networks using multiple sinks reduce packet loss. However, finding the optimum locations for the sinks has not been fully studied yet. Therefore, the authors sought to investigate whether the location of sinks can affect network parameters, such as capacity and delay. In this study, two schemes named popular-location scheme and random scheme are designed based on sink location. In the popular-location scheme, the sinks (base stations) are located around the popular points (most visited locations) according to the location popularity rule. However, in the random scheme, sinks are distributed randomly. The authors considered a cell-partitioned network to manage the signal interference between cells. The authors' results demonstrated that there is a trade-off between capacity and delay in both schemes. Additionally, the effect of packet redundancy on capacity and delay was investigated. Furthermore, by utilising the popularity rule, the network capacity and average delay improved significantly. Moreover, the authors' results indicate that packet redundancy does not affect the capacity, but it improves the delay.

Delay-Aware Energy-Efficient Routing towards a Path-Fixed Mobile Sink in Industrial Wireless Sensor Networks.

Wireless sensor networks (WSNs) involve more mobile elements with their widespread development in industries. Exploiting mobility present in WSNs for data collection can effectively improve the network performance. However, when the sink (i.e., data collector) path is fixed and the movement is uncontrollable, existing schemes fail to guarantee delay requirements while achieving high energy efficiency. This paper proposes a delay-aware energy-efficient routing algorithm for WSNs with a path-fixed mobile sink, named DERM, which can strike a desirable balance between the delivery latency and energy conservation. We characterize the object of DERM as realizing the energy-optimal anycast to time-varying destination regions, and introduce a location-based forwarding technique tailored for this problem. To reduce the control overhead, a lightweight sink location calibration method is devised, which cooperates with the rough estimation based on the mobility pattern to determine the sink location. We also design a fault-tolerant mechanism called track routing to tackle location errors for ensuring reliable and on-time data delivery. We comprehensively evaluate DERM by comparing it with two canonical routing schemes and a baseline solution presented in this work. Extensive evaluation results demonstrate that DERM can provide considerable energy savings while meeting the delay constraint and maintaining a high delivery ratio.

An Online Algorithm for Data Collection by Multiple Sinks in Wireless-Sensor Networks

Data collection by multiple sinks is a fundamental problem in wireless-sensor networks. Existing works focused on designing the optimal offline methods provided that the number and positions of sensors and sinks (or trajectories of mobile sinks) are predetermined. This may not be practical, because although sensors are cheap, sinks are quite expensive in reality. A more practical scenario is that sinks are deployed step by step during the network operation due budget constraints, and we do not know the number, positions, and capacities of sinks a priori. In this paper, we investigate the problem of data collection with multiple sinks, and design a suboptimal online algorithm via a primal-dual approach, requiring very little priori knowledge. We theoretically derive the competitive ratio of the online algorithm, and further improve it by finding the optimal sink location with an approximation ratio. We also analyze the computational complexity of the improved approach. Extensive simulations are conducted to demonstrate the performance of the proposed online algorithm and performance-complexity tradeoff.

The long-term prediction of the oil-contaminated water from the Sanchi collision in the East China Sea

The condensate and bunker oil leaked from the Sanchi collision would cause a persistent impact on marine ecosystems in the surrounding areas. The long-term prediction for the distribution of the oil-polluted water and the information for the most affected regions would provide valuable information for the oceanic environment protection and pollution assessment. Based on the operational forecast system developed by the First Institute of Oceanography, State Oceanic Administration, we precisely predicted the drifting path of the oil tanker Sanchi after its collision. Trajectories of virtual oil particles show that the oil leaked from the Sanchi after it sank is mainly transported to the northeastern part of the sink location, and quickly goes to the open ocean along with the Kuroshio. Risk probability analysis based on the outcomes from the operational forecast system for years 2009 to 2017 shows that the most affected area is at the northeast of the sink location.

On the performance of sink placement in WSNs considering energy-balanced compressive sensing-based data aggregation

This paper aims to address the problem of network lifetime in wireless sensor networks. Our analysis jointly considers the cluster-based routing, Compressive Sensing (CS) theory, load-balancing, and sink placement. We first provide a formulation to theoretically study the impact of the sink placement on the number of transmissions and the network lifetime. Then, we propose two data collection methods named “Energy-aware CS-based Data Aggregation (ECDA)” and “Energy-balanced High level Data aggregation Tree (EHDT)”. The proposed algorithms not only balance the energy consumption among different nodes, but also increase the network lifetime. As an advantage, both schemes are compatible with constant and mobile sinks. In this regard, considering the CS theory, we discuss the impact of the sink location and show the role of the sink mobility on the network performance. Although both algorithms improve the network lifetime, EHDT further considers the load-balancing problem in the network. It applies the weighted routing trees for transmitting data projections from the cluster heads to the sink and fairly distributes the energy consumption among different nodes. Numerical results confirm the efficiency of the proposed algorithms in terms of the number of transmissions, the energy consumption, the energy consumption variance, and the network lifetime.

Improving Wireless Sensor Networks Durability Through Efficient Sink Motion Strategy: TMSRP

Due to the huge potential profit that sensor networks may provide in industrial and socio-economic areas, they attract the attention of many researchers around the world. However, their development level has not reached an acceptable status due to several barriers. Each sensor is equipped with a battery but of limited energy which causes major obstacle on the lifetime of the network. These sensors have communicated with the sink which might be far away. A mobile sink can be considered as an alternative solution to the problems already identified, but it also raises new challenges such as the location of the mobile sink and communication with the sensors. In this paper, we proposed a new robust routing protocol called Tree and Mobile Sink-based Routing Protocol. This protocol is based on the intra-cluster multi-hop concept using a constructed tree for data routing and a new strategy for sink mobility to collect data from cluster heads. In order to evaluate the performance of algorithm, we implemented it using the NS2 network simulator.

Unital Design Based Sink Location Service for Wireless Sensor Networks

In wireless sensor networks (WSNs), providing source node with sink position is an essential principle for geographic routing protocols. Previous works have only focused on the problem of sink localization in a 2-D sensing field while that of 3-D WSNs has received little attention. Providing sink location service with low control overhead and energy consumption is a challenging issue in 3-D WSNs area. In this paper, we propose a unital design based sink location service (UDSL) for WSNs. In this scheme, sink location announcement (SLA) and sink location query (SLQ) packets are forwarded along two paths or blocks. The node located at the intersection of the two paths sends the sink position to the source. In the proposed method, SLA and SLQ messages are constructed using unital design blocks. For this purpose, a mapping from unital design to sink location service has been proposed. However, this basic mapping does not guarantee an intersection of paths,therefore, we propose an enhanced UDSL providing 100% probability of intersection. In order to analyze the proposed scheme’s performance, extensive WSNs simulations and experiments have been conducted. The results indicate that UDSL provides reasonable performance in terms of hop counts, path length, and energy consumption for providing sink location service.

Entropy generation and MHD natural convection of a nanofluid in an inclined square porous cavity: Effects of a heat sink and source size and location

The effects of a heat sink and the source size and location on the entropy generation, MHD natural convection flow and heat transfer in an inclined porous enclosure filled with a Cu-water nanofluid are investigated numerically. A uniform heat source is located in a part of the bottom wall, and a part of the upper wall of the enclosure is maintained at a cooled temperature, while the remaining parts of these two walls are thermally insulated. Both the left and right walls of the enclosure are considered to be adiabatic. The thermal conductivity and the dynamic viscosity of the nanofluid are represented by different verified experimental correlations that are suitable for each type of nanoparticle. The finite difference methodology is used to solve the dimensionless partial differential equations governing the problem. A comparison with previously published works is performed, and the results show a very good agreement. The results indicate that the Nusselt number decreases via increasing the nanofluid volume fraction as well as the Hartmann number. The best location and size of the heat sink and the heat source considering the thermal performance criteria and magnetic effects are found to be D = 0.7 and B = 0.2. The entropy generation, thermal performance criteria and the natural heat transfer of the nanofluid for different sizes and locations of the heat sink and source and for various volume fractions of nanoparticles are also investigated and discussed.

The Orbiting Carbon Observatory-2 early science investigations of regional carbon dioxide fluxes.

NASA's Orbiting Carbon Observatory-2 (OCO-2) mission was motivated by the need to diagnose how the increasing concentration of atmospheric carbon dioxide (CO2) is altering the productivity of the biosphere and the uptake of CO2 by the oceans. Launched on 2 July 2014, OCO-2 provides retrievals of the column-averaged CO2 dry-air mole fraction ([Formula: see text]) as well as the fluorescence from chlorophyll in terrestrial plants. The seasonal pattern of uptake by the terrestrial biosphere is recorded in fluorescence and the drawdown of [Formula: see text] during summer. Launched just before one of the most intense El Niños of the past century, OCO-2 measurements of [Formula: see text] and fluorescence record the impact of the large change in ocean temperature and rainfall on uptake and release of CO2 by the oceans and biosphere.

Cluster-Based Mobile Sink Location Management Scheme for Solar-Powered Wireless Sensor Networks

Cluster-Based Mobile Sink Location Management Scheme for Solar-Powered Wireless Sensor Networks

ACHIEVING ENERGY EFFICIENCY AND STABILITY IN WSN USING A NOVEL MOBILE SINK APPROACH BASED ON BIOGEOGRAPHY BASED OPTIMIZATION

Wireless sensor networks are constrained with limited battery lifetime. Cluster head near the base station act as relays to the cluster heads far from the base station resulting in fast depletion of the cluster head close to the base station. To overcome this problem mobile sink have been used in the past. The proposed algorithm finds the optimum path and sojourn location of the mobile sink using biogeography based optimization (BBO). BBO not only converge faster as compared to GA but it also gives more optimized results. The proposed algorithm is compared with previous protocols such as LEACH, GA based clustering, PSO based clustering. The algorithm is implemented using MATLAB simulation tool. The proposed algorithm performs better both in terms of lifetime of the cluster heads as well as lifetime of the entire network

A load balanced location service for location information management of multi-sink Wireless Sensor Networks

In many applications of Wireless Sensor Networks (WSNs), the network has a few mobile sinks in addition to a large number of static sensor nodes that gather information from their surrounding environment. The static sensor nodes in such applications use a location service to find the location of a mobile sink. Most of the proposed location services are useful in mobile ad hoc networks and are not efficient for WSNs. Furthermore, new protocols specifically designed for WSNs are not load balanced. Some sensor nodes relay more packets and deplete their energy quickly, hence reducing the network lifetime dramatically. In this paper, we propose a location service called Load Balanced Location Service (LBLS) for WSNs containing a few mobile sinks. LBLS selects four nodes in the network outline and only uses the location of these nodes. LBLS do not deplete the energy of specific nodes comparing to other mechanisms that forward location information messages toward selected nodes. We formally prove that in LBLS every sensor node can always locate any mobile node in the network. By using exhaustive simulation, we show that LBLS is a load balanced location service. Simulation results demonstrate the superiority of LBLS regarding the load balancing factor compared to most available related location services.

Economic Implications of CO2 Capture from the Existing as Well as Proposed Coal-fired Power Plants in India under Various Policy Scenarios

India is a country with rising energy needs. Much of the energy demand is met by coal and there are dynamic links between coal consumption and economic growth. However, the increasing coal use is likely to result in increasing carbon dioxide emissions. India's power sector contributes to about half of the all-India CO2 emissions. As a result, end-of-the-pipe abatement of CO2 in the power sector may be one of the prominent mechanisms to reduce India's greenhouse gas (GHG) emissions. Carbon capture and storage (CCS) technology may provide such a means in the Indian coal-fired power plants. This paper initially makes an effort to assess the economic implications of this technology on existing Indian coal-fired power plants. Some characteristic features of Indian power plants are identified with special reference towards CCS deployment. The importance of proximity of coal linkage and sink location from the power plant is established using the studied examples. General trends on the estimates of cost of electricity (COE), emission factor and net plant efficiency are evaluated. Subsequently, the trends in costs are projected for the next three decades for the upcoming plants using CCS. In these predictions, three scenarios of CCS deployment are considered, with varying carbon price range. In a high carbon price scenario (C price of US$ 80/t-CO2 in 2030), CCS is firmly established as a useful technology for the Indian coal-fired power plants by the year 2050.

Nitrogen retention and loss in unfertilized lawns across a light gradient

A desirable function for terrestrial urban ecosystems is the mitigation of nitrogen (N) pollution associated with cities and suburbs. To assist in maximizing this function, identifying locations of sources and sinks of N in the urban environment is crucial to inform management strategies. Lawns are an extensive land cover in urbanized landscapes, and in general, they have demonstrated the capacity to function as a sink for N inputs. How N is cycled by lawns, however, is likely not uniform across the physical heterogeneity or management activities that exist in lawns. We investigated the influence of heterogeneity in light availability on N cycling in lawns that were irrigated but not fertilized. Light availability is affected by tree canopy and built structures and is, therefore, heterogeneous both within individual lawns and among lawns. Light is expected to control N retention and loss through effects on primary productivity. We experimentally examined N regulation over one calendar year by measuring net primary production (NPP), N retention using an isotopic tracer, and N leaching in existing unfertilized lawns under heterogeneous light conditions. We used a budgetary approach to estimate gaseous N loss which we assume is primarily via denitrification. Light functioned as a limiting resource for primary productivity. From low to high light conditions, annual NPP increased 177 to 430 g C∙m−2∙y−1 and retention of N isotope tracer increased from 50 to 65% as a result of increased retention in plants. Nitrate leaching losses were low overall and were not affected by light levels. Light availability regulated the fate of N inputs and unfertilized lawns may function as substantial sinks for reactive N through storage in the terrestrial system and N loss by denitrification. However, whether or not denitrification is generally an N sink will depend on the ratio of non-reactive (i.e., N2) to reactive (i.e., N2O, NO) denitrification products. Overall, we find that effective strategies for managing N sources and sinks in cities will likely need to consider light availability, particularly in systems receiving water subsidies via irrigation.

Cross-border spread, lineage displacement and evolutionary rate estimation of rabies virus in Yunnan Province, China

BackgroundRabies is an important but underestimated threat to public health, with most cases reported in Asia. Since 2000, a new epidemic wave of rabies has emerged in Yunnan Province, southwestern China, which borders three countries in Southeast Asia.MethodWe estimated gene-specific evolutionary rates for rabies virus using available data in GenBank, then used this information to calibrate the timescale of rabies virus (RABV) spread in Asia. We used 452 publicly available geo-referenced complete nucleoprotein (N) gene sequences, including 52 RABV sequences that were recently generated from samples collected in Yunnan between 2008 and 2012.ResultsThe RABV N gene evolutionary rate was estimated to be 1.88 × 10−4 (1.37–2.41 × 10−4, 95% Bayesian credible interval, BCI) substitutions per site per year. Phylogenetic reconstructions show that the currently circulating RABV lineages in Yunnan result from at least seven independent introductions (95% BCI: 6–9 introductions) and represent each of the three main Asian RABV lineages, SEA-1, -2 and -3. We find that Yunnan is a sink location for the domestic spread of RABV and connects RABV epidemics in North China, South China, and Southeast Asia. Cross-border spread from southeast Asia (SEA) into South China, and intermixing of the North and South China epidemics is also well supported. The influx of RABV into Yunnan from SEA was not well-supported, likely due to the poor sampling of SEA RABV diversity. We found evidence for a lineage displacement of the Yunnan SEA-2 and -3 lineages by Yunnan SEA-1 strains, and considered whether this could be attributed to fitness differences.ConclusionOverall, our study contributes to a better understanding of the spread of RABV that could facilitate future rabies virus control and prevention efforts.

Derived Observations From Frequently Sampled Microwave Measurements of Precipitation—Part I: Relations to Atmospheric Thermodynamics

This is the first of two papers that quantify the high added value of frequent 3-D radar observations of the atmosphere to capture the dynamics of weather systems. Recent advances in small-satellite and radar technologies, such as the “Radar in Cubesat” developed at the Jet Propulsion Laboratory, are paving the way for the design of convoys of spaceborne radars that can directly observe the evolution of severe weather at very fine temporal scales. The analyses presented here are to establish the relation between such observations to the underlying cloud variables and processes, and to quantify the sensitivity to the different physical and instrument parameters. In this first part, a robust algorithm is proposed to estimate the horizontal advection from successive radar reflectivity measurements, and use it to compute total time derivatives $d_{t} Z$ of the observed radar reflectivity factors $Z$ . As illustrated using Next-Generation Radar measurements in a blizzard coupled with an atmospheric river in California, the maps of $d_{t} Z$ reveal features about locations of sources and sinks of condensed water, which are, otherwise, not visible in the maps of $Z$ alone. Using numerical simulations of the blizzard and a radiative-transfer model to forward calculate the corresponding reflectivity factors $Z$ in the S-band, we show the robust correlation between $d_{t} Z$ and the moistening of the troposphere.