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MCBT: Multi-Hop Cluster Based Stable Backbone Trees for Data Collection and Dissemination in WSNs  [PDF]
Inyoung Shin,Moonseong Kim,Matt W. Mutka,Hyunseung Choo,Tae-Jin Lee
Sensors , 2009, DOI: 10.3390/s90806028
Abstract: We propose a stable backbone tree construction algorithm using multi-hop clusters for wireless sensor networks (WSNs). The hierarchical cluster structure has advantages in data fusion and aggregation. Energy consumption can be decreased by managing nodes with cluster heads. Backbone nodes, which are responsible for performing and managing multi-hop communication, can reduce the communication overhead such as control traffic and minimize the number of active nodes. Previous backbone construction algorithms, such as Hierarchical Cluster-based Data Dissemination (HCDD) and Multicluster, Mobile, Multimedia radio network (MMM), consume energy quickly. They are designed without regard to appropriate factors such as residual energy and degree (the number of connections or edges to other nodes) of a node for WSNs. Thus, the network is quickly disconnected or has to reconstruct a backbone. We propose a distributed algorithm to create a stable backbone by selecting the nodes with higher energy or degree as the cluster heads. This increases the overall network lifetime. Moreover, the proposed method balances energy consumption by distributing the traffic load among nodes around the cluster head. In the simulation, the proposed scheme outperforms previous clustering schemes in terms of the average and the standard deviation of residual energy or degree of backbone nodes, the average residual energy of backbone nodes after disseminating the sensed data, and the network lifetime.
M-GEAR: Gateway-Based Energy-Aware Multi-Hop Routing Protocol for WSNs  [PDF]
Q. Nadeem,M. B. Rasheed,N. Javaid,Z. A. Khan,Y. Maqsood,A. Din
Computer Science , 2013,
Abstract: In this research work, we advise gateway based energy-efficient routing protocol (M-GEAR) for Wireless Sensor Networks (WSNs). We divide the sensor nodes into four logical regions on the basis of their location in the sensing field. We install Base Station (BS) out of the sensing area and a gateway node at the centre of the sensing area. If the distance of a sensor node from BS or gateway is less than predefined distance threshold, the node uses direct communication. We divide the rest of nodes into two equal regions whose distance is beyond the threshold distance. We select cluster heads (CHs)in each region which are independent of the other region. These CHs are selected on the basis of a probability. We compare performance of our protocol with LEACH (Low Energy Adaptive Clustering Hierarchy). Performance analysis and compared statistic results show that our proposed protocol perform well in terms of energy consumption and network lifetime.
Hop-distance relationship analysis with quasi-UDG model for node localization in wireless sensor networks  [cached]
Gao Deyun,Chen Ping,Foh Chuan,Niu Yanchao
EURASIP Journal on Wireless Communications and Networking , 2011,
Abstract: In wireless sensor networks (WSNs), location information plays an important role in many fundamental services which includes geographic routing, target tracking, location-based coverage, topology control, and others. One promising approach in sensor network localization is the determination of location based on hop counts. A critical priori of this approach that directly influences the accuracy of location estimation is the hop-distance relationship. However, most of the related works on the hop-distance relationship assume the unit-disk graph (UDG) model that is unrealistic in a practical scenario. In this paper, we formulate the hop-distance relationship for quasi-UDG model in WSNs where sensor nodes are randomly and independently deployed in a circular region based on a Poisson point process. Different from the UDG model, quasi-UDG model has the non-uniformity property for connectivity. We derive an approximated recursive expression for the probability of the hop count with a given geographic distance. The border effect and dependence problem are also taken into consideration. Furthermore, we give the expressions describing the distribution of distance with known hop counts for inner nodes and those suffered from the border effect where we discover the insignificance of the border effect. The analytical results are validated by simulations showing the accuracy of the employed approximation. Besides, we demonstrate the localization application of the formulated relationship and show the accuracy improvement in the WSN localization.
Determination Of Segmented Angular Shapes For Circular Areas Of Thermal Equipment
JK Nsiah
Journal of Science and Technology (Ghana) , 2009,
Abstract: Stable Food Crops Turning Into Commercial Crops: Case studies of Teff, Wheat and Rice in Ethiopia Most thermal equipment like industrial boilers, ceramic kilns, incinerators, thermal plants for electricity generation, have specially designed circular areas through which heat passes or generates. Since these areas are circular in design, fabrication and lining with refractory materials present technical problems that must be understood. Moreover, angular shapes that are required to construct circular areas are not readily available for procurement. These segmented angular shapes are not standardized, so depending on the make of the thermal equipment, suitable segments must be fabricated to fit. Moulds have to be fabricated and shapes cast out, using high temperature castables. These intricate procedures for the design and construction of circular segmented angular shapes have been, exhaustively, treated in this paper
Circular dichroism of cholesteric polymers and the orbital angular momentum of light  [PDF]
W. L?ffler,D. J. Broer,J. P. Woerdman
Physics , 2011, DOI: 10.1103/PhysRevA.83.065801
Abstract: We explore experimentally if the light's orbital angular momentum (OAM) interacts with chiral nematic polymer films. Specifically, we measure the circular dichroism of such a material using light beams with different OAM. We investigate the case of strongly focussed, non-paraxial light beams, where the spatial and polarization degrees of freedom are coupled. Within the experimental accuracy, we cannot find any influence of the OAM on the circular dichroism of the cholesteric polymer.
An improved upper limit to the CMB circular polarization at large angular scales  [PDF]
R. Mainini,D. Minelli,M. Gervasi,G. Boella,G. Sironi,A. Bau',S. Banfi,A. Passerini,A. De Lucia,F. Cavaliere
Physics , 2013, DOI: 10.1088/1475-7516/2013/08/033
Abstract: Circular polarization of the Cosmic Microwave Background (CMB) offers the possibility of detecting rotations of the universe and magnetic fields in the primeval universe or in distant clusters of galaxies. We used the Milano Polarimeter (MIPOL) installed at the Testa Grigia Observatory, on the italian Alps, to improve the existing upper limits to the CMB circular polarization at large angular scales. We obtain 95% confidence level upper limits to the degree of the CMB circular polarization ranging between 5.0x10^{-4} and 0.7x10^{-4} at angular scales between 8 and 24 deg, improving by one order of magnitude preexisting upper limits at large angular scales. Our results are still far from the nK region where today expectations place the amplitude of the V Stokes parameter used to characterize circular polarization of the CMB but improve the preexisting limit at similar angular scales. Our observations offered also the opportunity of characterizing the atmospheric emission at 33 GHz at the Testa Grigia Observatory.
Validity Check of Mutual Inductance Formulas for Circular Filaments with Lateral and Angular Misalignments
Slobodan I. Babic;Frederic Sirois;Cevdet Akyel
PIER M , 2009, DOI: 10.2528/PIERM09060105
Abstract: In this paper we derived the formula for calculating the mutual inductance between circular filaments with lateral and angular misalignment by using the approach of the magnetic vector potential. The results obtained correspond to those of F. W. Grover, although the latter used the general formula given by the Neumann integral instead of a vector potential approach. However, the major purpose of this paper is to clarify some confusion introduced in previous works regarding the mutual inductance calculation between thin filamentary circular coils with parallel axes in air. This problem has been solved by Kim et al. (1997) using the magnetic vector potential, but unfortunately it leads to erroneous results, even for slight misalignments of the coils' center axes. This is why we chose to use the approach of the magnetic vector potential to show that, when properly derived, the results must indeed reduce to the well known F.W. Grover's formulas.
Angular momentum-induced circular dichroism in non-chiral nanostructures  [PDF]
Xavier Zambrana-Puyalto,Xavier Vidal,Gabriel Molina-Terriza
Physics , 2014, DOI: 10.1038/ncomms5922
Abstract: Circular dichroism (CD), i.e. the differential response of a system to left and right circularly polarized light, is one of the only techniques capable of providing morphological information of certain samples. In biology, for instance, CD spectroscopy is widely used to study the structure of proteins. More recently, it has also been used to characterize metamaterials and plasmonic structures. Typically, CD can only be observed in chiral objects. Here, we present experimental results showing that a non-chiral sample such as a sub-wavelength circular nano-aperture can produce giant CD when a vortex beam is used to excite it. These measurements can be understood by studying the symmetries of the sample and the total angular momentum that vortex beams carry. Our results show that CD can provide a wealth of information about the sample when combined with the control of the total angular momentum of the input field.
Detecting Chiral Orbital Angular Momentum by Circular Dichroism ARPES  [PDF]
Jin-Hong Park,Choong H. Kim,Jun Won Rhim,Jung Hoon Han
Physics , 2011, DOI: 10.1103/PhysRevB.85.195401
Abstract: We show, by way of tight-binding and first-principles calculations, that a one-to-one correspondence between electron's crystal momentum k and non-zero orbital angular momentum (OAM) is a generic feature of surface bands. The OAM forms a chiral structure in momentum space much as its spin counterpart in Rashba model does, as a consequence of the inherent inversion symmetry breaking at the surface but not of spin-orbit interaction. Circular dichroism (CD) angle-resolved photoemission (ARPES) experiment is an efficient way to detect this new order, and we derive formulas explicitly relating the CD-ARPES signal to the existence of OAM in the band structure. The cases of degenerate p- and d-orbital bands are considered.
(EERSM): Energy-Efficient Multi-Hop Routing Technique in Wireless Sensor Networks Based on Combination between Stationary and Mobile Nodes  [PDF]
Fawaz Alassery
Journal of Computer and Communications (JCC) , 2019, DOI: 10.4236/jcc.2019.74004
Abstract: In Wireless Sensor Network (WSNs), sensor nodes collect data and send them to a Base Station (BS) for further processing. One of the most issues in WSNs that researchers have proposed a hundred of technique to solve its impact is the energy constraint since sensor nodes have small battery, small memory and less data processing with low computational capabilities. However, many researches efforts have focused on how to prolong the battery lifetime of sensor nodes by proposing different routing, MAC, localization, data aggregation, topology construction techniques. In this paper, we will focus on routing techniques which aim to prolonging the network lifetime. Hence, we propose an Energy-Efficient Routing technique in WSNs based on Stationary and Mobile nodes (EERSM). Sensing filed is divided into intersected circles which contain Mobile Nodes (MN). The proposed data aggregation technique via the circular topology will eliminate the redundant data to be sent to the Base Station (BS). MN in each circle will rout packets for their source nodes, and move to the intersected area where another MN is waiting (sleep mode) to receive the transmitted packet, and then the packet will be delivered to the next intersected area until the packet is arrived to the BS. Our proposed EERSM technique is simulated using MATLAB and compared with conventional multi-hop techniques under different network models and scenarios. In the simulation, we will show how the proposed EERSM technique overcomes many routing protocols in terms of the number of hops counted when sending packets from a source node to the destination (i.e. BS), the average residual energy, number of sent packets to the BS, and the number of a live sensor nodes verse the simulation rounds.
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