Stable Cluster Formation Research Articles

SeAC: SDN-Enabled Adaptive Clustering Technique for Social-Aware Internet of Vehicles

Since millions of smart vehicles in Internet-of-Vehicles (IoV) produce and relay data to analyze road conditions, creating social networks of vehicles in IoV is an important factor for the future Intelligent Transportation System (ITS). Likewise, the IoV architecture has seen vertical fragmentation of approaches used to meet the needs of different work domains. Therefore, IoV in combination with social networking, called Social IoV (SIoV), was created to address these alleged problems. However, one of the challenges in SIoV is that the social relations between vehicles grow and deplete very fast due to the extremely dynamic and unstable nature of the IoV. Therefore, a clustering-based scheme for SIoV, which is efficient in terms of stability can overcome this problem. We propose : an SDN-enabled adaptive clustering technique for SIoV. uses a 3D modeling approach to construct logical clusters that are based on factors such as physical location, social tie, and interest similarity among vehicles. Therefore, improves the stability of clusters and the efficiency of the underlying SIoV architecture. Additionally, by minimizing the trade-off between social and physical distances, lowers communication and computation costs. We evaluate, and the simulation results show that for two different topologies, the adaptive approach using can produce better results in terms of a stable cluster formation.

Theoretical Study of the Gas-Phase Hydrolysis of Formaldehyde to Produce Methanediol and Its Implication to New Particle Formation.

Aldehydes were speculated to be important precursor species in new particle formation (NPF). The direct involvement of formaldehyde (CH2O) in sulfuric acid and water nucleation is negligible; however, whether its atmospheric hydrolysate, methanediol (CH2(OH)2), which contains two hydroxyl groups, participates in NPF is not known. This work investigates both CH2O hydrolysis and NPF from sulfuric acid and CH2(OH)2 with quantum chemistry calculations and atmospheric cluster dynamics modeling. Kinetic calculation shows that reaction rates of the gas-phase hydrolysis of CH2O catalyzed by sulfuric acid are 11-15 orders of magnitude faster than those of the naked path at 253-298 K. Based on structures and the calculated formation Gibbs free energies, the interaction between sulfuric acid/its dimer/its trimer and CH2(OH)2 is thermodynamically favorable, and CH2(OH)2 forms hydrogen bonds with sulfuric acid/its dimer/its trimer via two hydroxyl groups to stabilize clusters. Our further cluster kinetic calculations suggested that the particle formation rates of the system are higher than those of the binary system of sulfuric acid and water at ambient low sulfuric acid concentrations and low relative humidity. In addition, the formation rate is found to present a negative temperature dependence because evaporation rate constants contribute significantly to it. However, cluster growth is essentially limited by the weak formation of the largest clusters, which implies that other stabilizing vapors are required for stable cluster formation and growth.

Congestion-free routing based on a hybrid meta-heuristic algorithm to provide an effective routing protocol by analyzing the significant impacts of QoS parameters in a dynamic VANET environment

Abstract A definitive form of Mobile Ad-hoc Network (MANET) is the Vehicular Ad-hoc Network (VANET), which delivers data communication using wireless transmission with the collection of vehicular nodes in a vehicular environment. The main goal of this VANET is to improve the Quality of Service (QoS) which is road safety, environmental kindliness, and logistics in intelligent transport. Moreover, mobility and routing play an important challenge for information interchange to the process in the VANET environment. In developing countries, smart cities are encountering problematic traffic congestion. Furthermore, in cluster communications, stable cluster formation and maintenance with the guarantying QoS has always remained a great challenge. In order to overcome the above-mentioned issue, this article proposes a congestion-free routing process ensuring QOS parameters. The main objective of the proposed scheme is to analyze the impact of QOS parameters while choosing the best routing path in Vehicular communication. The scheme also introduces the Hybrid-Harris Hawks Black Widow optimization-based VANET (H-HHBW-VANET) algorithm to improve QoS for routing between nodes. This algorithm differs from other algorithms in terms of optimal solution generation, which makes it more efficient. The proposed work is implemented in the working platform of NS2 to analyze the parameters such as Drop, Delay, Energy Consumption, Throughput, and Fairness Index. The simulation results provide better QOS service in terms of low energy consumption with higher throughput and low delay.

Stable coalitions for urban-VANET: A hedonic game approach

This paper tackles the problem of improving the coalitions' stability for Quality of Service Optimized Link State Routing (QoS-OLSR) protocol in urban Vehicular Ad-hoc Networks (VANETs). VANETs have introduced communication among vehicles for the Intelligent Transportation System (ITS) allowing several safety and user-oriented applications to be implemented in an ad-hoc manner. The routing protocols in VANET play a significant role in the delivery of data packets for such applications. However, the rapid changes in the topology of urban-VANET affect the relative stability among moving vehicles and consequently cause a high drop in the network performance. Several works considered urban metrics and game theory models for stable relay selection and cluster formation where the stability of a relay is measured compared to all the neighbor vehicles rather than selection based on relative stability between a vehicle and its relay. In addition, some works proposed matching theory that focuses on the individual preferences of players, to introduce stability. Alternatively, the Hedonic game considers preferences and enhances stability through joining coalitions to improve the overall utility of all participating members in each coalition. Therefore, in this paper, we propose a two-phase Hedonic game model that improves the coalitions' stability for QoS-OLSR in urban-VANET by considering the urban characteristics such as traffic lights, intersections, and lanes' directions. Players play the game in an ad-hoc manner by exchanging a set of messages and join coalitions that include relatively more stable members. Hence, the relative stability among coalition members is the utility of the coalition. A coalition utility depends on the urban characteristics which affect several metrics such as the time to leave the street and the probability of the direction to leave the nearest intersection. Simulations, that are conducted using SUMO and NS3, show high network performance in terms of packet delivery ratio, throughput, and end-to-end delay compared to benchmark protocols.

Analysis of GPI-Anchored Receptor Distribution and Dynamics in Live Cells by Tag-mediated Enzymatic Labeling and FRET.

The analysis of glycosylphosphatidylinositol (GPI)-anchored receptor distribution and dynamics in live cells is challenging, because their clusters exhibit subdiffraction-limited sizes and are highly dynamic. However, the cellular response depends on the GPI-anchored receptor clusters’ distribution and dynamics. Here, we compare three approaches to GPI-anchored receptor labeling (with antibodies, fluorescent proteins, and enzymatically modified small peptide tags) and use several variants of Förster resonance energy transfer (FRET) detection by confocal microscopy and flow cytometry in order to obtain insight into the distribution and the ligand-induced dynamics of GPI-anchored receptors. We found that the enzyme-mediated site-specific fluorescence labeling of T-cadherin modified with a short peptide tag (12 residues in length) have several advantages over labeling by fluorescent proteins or antibodies, including (i) the minimized distortion of the protein’s properties, (ii) the possibility to use a cell-impermeable fluorescent substrate that allows for selective labeling of surface-exposed proteins in live cells, and (iii) superior control of the donor to acceptor molar ratio. We successfully detected the FRET of GPI-anchored receptors, T-cadherin, and ephrin-A1, without ligands, and showed in real time that adiponectin induces stable T-cadherin cluster formation. In this paper (which is complementary to our recent research (Balatskaya et al., 2019)), we present the practical aspects of labeling and the heteroFRET measurements of GPI-anchored receptors to study their dynamics on a plasma membrane in live cells.

Joint design of coalition formation and semi-blind channel estimation in fog radio access networks

Coordinated signal processing can obtain a huge transmission gain for Fog Radio Access Networks (F-RANs). However, integrating into large scale, it will lead to high computation complexity in channel estimation and spectral efficiency loss in transmission performance. Thus, a joint cluster formation and channel estimation scheme is proposed in this paper. Considering research remote radio heads (RRHs) centred serving scheme, a coalition game is formulated in order to maximize the spectral efficiency of cooperative RRHs under the conditions of balancing the data rate and the cost of channel estimation. As the cost influences to the necessary consumption of training length and estimation error. Particularly, an iterative semi-blind channel estimation and symbol detection approach is designed by expectation maximization algorithm, where the channel estimation process is initialized by subspace method with lower pilot length. Finally, the simulation results show that a stable cluster formation is established by our proposed coalition game method and it outperforms compared with full coordinated schemes.

Evolutionary Games for Correlation-Aware Clustering in Massive Machine-to-Machine Networks

In this paper, the problem of self-organizing, correlation-aware clustering is studied for a dense network of machine-type devices (MTDs) deployed over a cellular network. In dense machine-to-machine networks, MTDs are typically located within close proximity and gather correlated data, and, thus, clustering MTDs based on data correlation leads to a decrease in the number of redundant bits transmitted to the base station. The clustering problem is formulated as an evolutionary game, which models the interactions among a massive number of MTDs, in order to decrease MTD transmission power. A novel utility function that captures the tradeoff between minimizing the average MTD transmission power per cluster and maximizing cluster size (or minimizing signaling overhead) is proposed. To solve this game, a distributed algorithm is proposed to allow a massive number of MTDs to autonomously form clusters. It is shown that the proposed distributed algorithm converges to an evolutionary stable strategy (ESS) that is robust to a small portion of MTDs deviating, e.g., due to some stochastic changes in the M2M environment from the stable cluster formation at convergence. The maximum fraction of MTDs that can deviate from the ESS, while still maintaining a stable cluster formation, is derived. Simulation results show the efficiency of the proposed algorithm in clustering MTDs with highly correlated data: on average, the proposed approach yields reductions of up to 44.1% and 15.25% in terms of the transmit power per cluster, compared to forming clusters with the maximum possible size and uniformly selecting a cluster size, respectively.

Influence of the cluster formation in a magnetic particle suspension on heat production effect in an alternating magnetic field

In the present study, we concentrate on the results of the unexpected characteristic that the stable particle cluster formation induces a decrease in the degree of heating effect in an alternating magnetic field, by means of Brownian dynamics simulations. If chain-like clusters are stably formed in the system, whether or not a large heating effect is obtained is dependent on the magnitude relationship between the magnetic particle-particle and the magnetic particle-field interaction strengths. As the magnetic particle-particle interaction strength increases and becomes more dominant than the influence of the magnetic field, the magnetic moments of stable chain-like clusters do not have a sufficient tendency to inline in the field direction. This leads to a smaller area of the hysteresis loop, and therefore the stable cluster formation induces a significant decrease in the heating effect.

Expansion of Cluster Head Stability Using Fuzzy in Cognitive Radio CR-VANET

The Vehicular Ad Hoc Network (VANET) plays a vital role in the development of smart cities, especially in ensuring vehicles' safety on roads. However, VANET wireless-based networks face some challenges such as security, stability, communication, and reliability. To resolve these issues, we propose a fuzzy cluster head selection scheme in Cognitive Radio (CR) VANET, which uses the CR technology for the spectrum sensing algorithm. In this technology, the free spectrums of the primary user are utilized by secondary users without any correlation. Moreover, we have considered some input parameters such as vehicles' average velocity, distance, network connectivity level, lane weight and trustworthiness for the fuzzy system based CR VANET in this research. The selected cluster head provides stability and reliability to the cluster compared to the state of art techniques. Extensive experiments were conducted in order to evaluate the effectiveness of the proposed approach. However, simulation results authenticate more stable and secure cluster formation using the proposed fuzzy logic based CR VANET.

Stable femtocells cluster formation and resource allocation based on cooperative game theory

In this paper, we address the problem of forming stable groups of femtocells that can reduce the complexity of the resource management and enhance the subscribers’ satisfaction while guaranteeing the service to nearby public users. In a macro-femtocell network, the resource management becomes a very challenging task as the number of deployed femtocells increases. Several strategies of clustering have been proposed to allocate resources in a distributed manner. However, forming stable clusters of femtocells is yet to be addressed. We propose a distributed cluster-based resource allocation framework that consists of three components: (1) a base station selection algorithm for public users that guarantees them a high data rate, (2) a coalition game, where femtocells are grouped into stable clusters to reduce the resource allocation complexity, and (3) a fair resource allocation using the Shapley value to compute the payoff of each cluster member based on Particle Swarm Optimization algorithm. The ε-core concept from game theory is used as the stability criteria to form the clusters. A performance comparison is carried out between the proposed solution and two benchmark models: a centralized approach and a distributed approach with non-stable group formation. Simulation results show that our framework indeed increases the network throughput, provides higher subscribers satisfaction, and higher Jain fairness index for the distribution of resources among the existing users in the femto-tier.

Asymmetric polar localization dynamics of the serine chemoreceptor protein Tsr in Escherichia coli.

The spatial location of proteins in living cells can be critical for their function. For example, the E. coli chemotaxis machinery is localized to the cell poles. Here we describe the polar localization of the serine chemoreceptor Tsr using a strain synthesizing a fluorescent Tsr-Venus fusion at a low level from a single-copy chromosomal construct. Using photobleaching and imaging during recovery by new synthesis, we observed distinct asymmetry between a bright (old) pole and a dim (new) pole. The old pole was shown to be a more stable cluster and to recover after photobleaching faster, which is consistent with the hypothesis that newly synthesized Tsr proteins are inserted directly at or near the old pole. The new pole was shown to be a less stable cluster and to exchange proteins freely with highly mobile Tsr-Venus proteins diffusing in the membrane. We propose that the new pole arises from molecules escaping from the old pole and diffusing to the new pole where a more stable cluster forms over time. Our localization imaging data support a model in which a nascent new pole forms prior to stable cluster formation.

The route to synchrony via drum head mode and mixed oscillatory state in star coupled Hindmarsh–Rose neural network

Network of coupled oscillators exhibit different types of spatiotemporal patterns. We report that as the coupling strength increases the unidirectionally coupled Hindmarsh–Rose neuron star network will synchronize. The condition for synchronization has been evaluated using Lyapunov function method. We also discuss the dynamics of the system in the presence of controllers. The control input generate interesting behaviors which consist of clusters of spatially coherent domains depending on the coupling strength. Drum head mode, mixed oscillatory state, desynchrony, and multi cluster states are formed and cluster reduction takes place before settling to complete synchrony. The evolution of a perfectly synchronized state via drum head mode, mixed oscillatory state, and clusters from a desynchronized state is reported for the first time. The parameter values which lead to stable cluster formation is also discussed. Our results suggest that in the presence of controllers the common oscillator in the star network behaves as a driver and generates the transitions and cluster formation acts as a precursor to complete synchrony in Hindmarsh–Rose model with unidirectional star coupling.

QOS enabled data dissemination in hierarchical VANET using machine learning approach

Vehicular ad hoc networks (VANETs) are a collection of vehicular nodes that perform as a mobile hosts form a temporary network without the aid of any centralised infrastructure, so it is a sub-class of ad hoc network. It ensures the quality of service (QoS) for different VANET applications. Although it provides the QoS services to the process, mobility and routing play an important challenge in the VANET environment. So, different researches have revealed that the hierarchical routing schemes have numerous benefits over the traditional ones. Stable cluster formation and maintenance with the guarantying QoS in intra-cluster communications has always remained as a great challenge. For overcoming this issue, this paper proposes a QoS enabled data dissemination using an improved Kruskal's algorithm to provide efficient data dissemination and QoS in hierarchical VANET. This approach constructs the minimum spanning trees using Kruskal's algorithm in every road segment, where the vehicle has been clustered using the fuzzy c-means clustering method by considering the intra-cluster QoS. Each spanning tree will have a cluster head that is responsible to collect the data from the leaf nodes and disseminates the data to other coordinator nodes and vice versa. The simulation results show that the proposed approach performs better than the existing routing approach in terms of delay, throughput and packet loss.

WSN Performance Issues and Various Clustering Methods

There are several application have been developed with need of self organization for network. To fulfill this requirement need of wireless sensor network in such applications. To manage network efficiently clustering is used. Lots of works have been done in field of wireless sensor networks (WSNs) in last few years. These researches have boost potential of WSNs in applications such as security monitoring, disaster management, military area, border protection and health monitoring systems. Such applications are required to be remotely deployed sensor nodes in huge numbers and to operate autonomously. So there need to scalability, nodes are often collected into disjoint clusters. This paper, presents a categorization and common organization of available clustering proposal. This work analysis various clustering algorithms used for WSNs and give a review with focusing on their objectives features, etc. and proposed efficient clustering method for stable cluster formation and maintenance.

Fuzzy Logic-based Mobility Metric Clustering Algorithm for MANETs

Mobile ad-hoc network, (MANET) is a collection of wireless mobile nodes dynamically forming a temporary communication network without using any existing infrastructure or centralized administration. To reduce routing overhead, computational complexity and overcome the problem of low bandwidth utilization, MANET is divided into several clusters. The authors propose a fuzzy logic based mobility metric for MANET that had been utilized as the basis of cluster formation in the algorithm viz., FUZZY CLUSTERING. This algorithm leads to more stable cluster formation compared to the existing MOBIC algorithm as evidenced by significant reduction in the number of clusterhead changes. As the frequency of cluster reorganization is a significant attribute, the proposed algorithm is expected to yield improved performance for MANETs.

ECBRP: An Efficient Cluster-Based Routing Protocol for Real-Time Multimedia Streaming in MANETs

The dynamic characteristics of wireless networks and stringent QoS requirements of multimedia applications identify significant challenges for providing QoS guarantees for real-time multimedia streaming in such wireless environment. QoS routing protocols can decisively contribute to the QoS provision of network systems. This paper proposes an efficient cluster-based routing protocol (ECBRP) for real-time multimedia streaming in mobile ad hoc networks. First, to improve the stability of clusterheads, we introduce a new algorithm of cluster formation, in consideration of the node mobility and connectivity. Second, a link-broken detection mechanism is designed, which is able to distinguish whether packet loss is due to mobility or congestion, and to make proper reaction. This mechanism contributes to reduce route overhead, and to increase the decodable ratio of video frame at the application layer as well. Third, the routing protocol is enhanced via an adaptive packet salvage strategy, in order to alleviate the congestion in consideration of the characteristics of multimedia traffic. Our simulation experiment results demonstrate that the ECBRP leads to more stable cluster formation than the CBRP, and 80% decreases in the frequency of clusterhead changes against CBRP. As a result, the quality of real-time multimedia streaming is improved significantly, in terms of decodable frame ratio, delay and delay jitter, etc.

Structural Study of Selected Polyhalogenated Benzimidazoles (Protein Kinase CK2 Inhibitors) by Nuclear Quadrupole Double Resonance, X-ray, and Density Functional Theory

Protein kinase CK2 inhibitors, polyhalogenated benzimidazoles, have been studied experimentally in solid state by NMR-NQR double resonance and X-ray and theoretically by the density functional theory (DFT). Six resonance frequencies on (14)N have been detected and assigned to particular nitrogen sites in each polyhalogenated benzimidazole molecule. The effects of prototropic annular tautomerism and polymorphism related to stable cluster formation due to intermolecular hydrogen bonding interactions on the (14)N NQR parameters have been analyzed within the DFT and AIM (atoms in molecules) formalism. The studies suggest that all polyhalogenobenzimidazoles are isostructural and can exhibit polymorphism and that (14)N NQR is very sensitive to hydrogen bondings but less sensitive to the specific arrangement of the hydrogen bonded molecules. NQDR and DFT results suggest the presence of the prototropic annular tautomerism 50:50, which is in a good agreement with the X-ray and (1)H NMR data.

Stable cluster formation in aqueous suspensions of iron oxyhydroxide nanoparticles

Metal oxide and oxyhydroxide nanoparticles are important components of natural aqueous systems and have application in photocatalysis. Uncoated (oxyhydr)oxide nanoparticles can form charge-stabilized colloids in water, but the precise regimes of dispersion and aggregation have been determined for very few nanomaterials. We studied the colloidal behavior of ∼6 nm nanoparticles of iron oxyhydroxide (FeOOH), a common natural nanoscale colloid, and found that these nanoparticles formed stable suspended clusters under a range of aqueous conditions. Light and X-ray scattering methods show that suspended fractal nanoclusters are formed between pH 5 and 6.6 with well-defined maximum diameters that can be varied from 25 nm to approximately 1000 nm. The nanoclusters retain a very high surface area, and persist in suspension for at least 10 weeks in solution. The process is partially reversible because optically transparent suspensions are regained when nanoparticles that aggregated and settled at pH >7 are adjusted to pH 4 without stirring. However, completely redispersed nanoparticles are not obtained even after one month. Because nanocluster formation is controlled predominantly by surface charge, we anticipate that many metal oxide and other inorganic nanoparticles will exhibit equivalent cluster-forming behavior. Our results indicate that natural nanoparticles could form stable nanoclusters in groundwater that are likely to be highly mobile, with implications for the long-range transport of surface sorbed contaminants.

Gradual decreasing characteristics and temperature stability of electric resistivity in water triggered with milligauss AC field

Gradual decreasing characteristics of electric resistivity in highly purified water triggered with a 10 mG (1 /spl mu/T) ac field were investigated for frequencies ranging from 1 Hz to 15 MHz. The temperature stability of the resistivity was also measured in various magnetized waters. The mechanism of the gradual decrease of resistivity after short-time application of a milligauss ac field is discussed, considering the cyclotron resonance for stable hydromolecular cluster formation for long-range ordered proton transport.

Fullerene superconductivity by short-range order instability

For the fullerene-group (C60 group) of metastable materials a novel model is conceptualized on the basis of a special dynamic clustering. This clustering is realized by a short-range instability through a collective, cooperative, and coherent displacement of the ions to seek for the most dense and most stable cluster formation. In the C60 superconductivity, mediation by harmonic lattice vibrations (phonons) is replaced by a pairing mechanism with anharmonic collective and coherent cluster vibrations. The suggested model fits the experimental data surprisingly well.