Stable Link Research Articles

Xiroi ASV: a Modular Autonomous Surface Vehicle to Link Communications

This paper presents the design of Xiroi: a modular Autonomous Surface Vehicle (ASV) built to guarantee a stable and continuous Acoustic Communication Link (ACL) between an underwater vehicle and a remote computer, either located on the shore or on a support vessel. The ASV is commanded to automatically ensure a close distance for the ACL by following the submarine platform when underwater, and keeping a safety distance when it surfaces. The platform can be operated in the following ways: (i) Autonomous Underwater Vehicle (AUV) tracking, where the vehicle is required to track a moving frame (e.g. the AUV) without the need to know the actual position of the platform, (ii) path following, where the objective of the vehicle is to achieve a number of waypoints in a time window and (iii) station keeping, where the vehicle holds its GPS position regardless of the wind or water currents.

On the Design of Computation Offloading in Cache-Aided D2D Multicast Networks

As the demand of data-hungry and computing intensive tasks grows dramatically, cache-aided device-to-device multicast (D2MD) networks are introduced, which can offload traffic from the base stations to D2D users (DUEs) directly to alleviate the heavy burden on backhaul links and improve the energy and spectrum efficiency. However, most previous works ignored the limitation of battery power and scarce computing capabilities of DUEs. In this paper, we study the computation and traffic offloading in cache-aided D2MD networks for the content delivery and delay sensitive task offloading services. Firstly, in order to provide stable multicast links and enhanced computing resources, a D2D cluster head (DCH) selection strategy is proposed that jointly considers the social attributes, available energy, and transfer rate of DUEs. Secondly, to improve the efficiency of content distribution and optimize the energy consumption of content delivery, we propose a novel multicast-aware coded and cooperative caching scheme, which may increase the opportunity for D2D multicasting to obtain the desired contents. Thirdly, considering the DUEs association, uplink full duplex DCH transmission power allocation, and mobile edge computing computation resource scheduling, an optimization computation offloading model is formulated. On this basis, we model the computation offloading and resource allocation optimization problem. Furthermore, we transform this problem into user allocation optimization problem and resource allocation optimization problem (RAOP), and RAOP is proved as a convex problem, and the optimal resource allocation solution is found. Finally, the simulation results show that our proposed schemes can effectively decrease the energy consumption and computing costs.

Русская эмигрантская община в Тулоне в 1920—1930-х годах: формирование и состав

The process of formation of the Russian emigrant colony in the South French city of Toulon in the period between world wars is considered. The relevance and novelty of this study is determined by the fact that it is based on an extensive set of archival documents, first introduced into scientific circulation, the history of the formation of a new center of Russian emigration in France is examined. Analyzing the process of formation of the Russian community in this region, the author pays attention to the political events that preceded the appearance of Russian immigrants in the city. The article describes the economic and socio-cultural context of the city at the time of arrival of refugees. The paper presents the results of a comparative analysis of statistical data on the quantitative and gender composition of the Russian community of Toulon in the studied period. The question of social and professional belonging of this group of immigrants is raised. It is shown that the process of formation and change in the composition of the Russian colony in Toulon is inscribed in the overall economic context of the region. It is emphasized that one of the important factors that influenced the development of the Russian community was the lack of stable links between the labour integration of immigrants and the choice of place of residence. The author dwells on the problem of intra-community relations and external factors that influenced the changes in the quantitative composition of the Russian community.

Bilateral clavicular hypoplasia and cleidocranial dysplasia: Case report

Clavicular hypoplasia or agenesis is common in patients with cleidocranial dysplasia (CCD). CCD is an uncommon congenital pathology with an autosomal dominant pattern affecting males and females equally. CCD presents with wide phenotypic variability, but there is no stable link between the genotype and phenotype. In addition to clavicular hypoplasia/agenesis, such patients present with thoracic deformities, iliac hypoplasia, cranial bone deformities, and delayed dentition. An early diagnosis is important to determine treatment options. However, there is no specific orthopedic treatment for this disease.

Enhanced master/slave control strategy enabling grid support services and offshore wind power dispatch in a multi-terminal VSC HVDC transmission system

New high voltage direct current (HVDC) installations are expected to be able to provide stability support to the main synchronous networks to which they are connected. In multi-terminal HVDC (MTDC) schemes incorporating offshore wind farm this issue could be addressed by setting aside a reserve of wind energy by the curtailment of wind turbine generators (WTGs).This paper proposes a communication-less dc voltage cooperative control strategy for MTDC transmission systems. A grid side converter, the master, and a wind farm are designed to work cooperatively to maintain a stable dc link voltage, facilitating normal power dispatch orders and the provision of frequency support. The proposed control maintains a wind energy reserve and uses a flexible dc link voltage at the master converter. Allowing the local master dc voltage to vary within certain limits encourages the wind farm to participate in dc link voltage control and hence no communication system is required. The master converter automatically assumes control of the dc link voltage in the absence of wind or when the wind reserve is used up.A four terminal MTDC system comprising one master converter, two active/reactive power converters and one wind farm is studied. The effectiveness of the proposed control strategy is validated through simulation using MATLAB®-SIMULINK®.

Path Observation Based Physical Routing Protocol for Wireless Ad Hoc Networks

Wireless ad hoc networks are going to be an emerged multi-hop communication exploit among mobiles to deliver data packets. The special characteristics of Wireless network make the communication link between mobiles to be unreliable. To handle high mobility and environmental obstacles, most of physical routing protocols do not consider stable links during packet transmission which lead to higher delay and packet dropping in network. In this paper, we propose path observation based physical routing protocol named POPR for WANET. The proposed routing protocol incorporates relative distance, direction and mid-range forwarder node with traffic density to forward the data toward destination in order to improve physical forwarding between and at the intersection. Simulation results show that the proposed routing protocol performs better as compared to existing solutions.

Direct electrochemical DNA biosensor based on reduced graphene oxide and metalloporphyrin nanocomposite

A novel electrochemical DNA sensor based on self-assembled nanocomposite of a π-conjugated structure of reduced graphene oxide (RGO) and a modified manganese (III) tetraphenylporphyrin (MnTPP) was described. The composite MnTPP/RGO was formed through π−π stacking interactions between aromatic rings of graphene sheets and porphyrin macrocycle. Porphyrin molecules are versatile compounds that are easily functionalized with numerous reactive groups and also capable of incorporating many redox metals for electrochemical characterization. In this work, we synthesized the 5-[4-(4-carboxypropanoxy)phenyl]-10,15,20-triphenylporphyrin functionalized with a carboxylic group designed for covalent attachment of 5′-amino single-strand DNA through stable amide link. The MnTPP/RGO platform was characterized by Fourier Transform infrared spectroscopy (FT-IR), UV–visible spectroscopy and electrochemical methods. We demonstrated that the two-dimensional structure and conjugated system of graphene allowed strong interactions of metalloporphyrins and their immobilization on the surface of graphene without loss structural and conductive properties of the graphene. Electrochemical investigations performed by square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) provided that the RGO possessed excellent conductivity and facilitated the electron transfer of redox species. DNA immobilization and hybridization with complementary sequences lead to the change of electrochemical MnTPP/RGO properties. EIS demonstrated an increase of impedance after DNA probe grafting and hybridization. A detection limit of 6×10−14M has been calculated and a dynamic range of 100aM to 10pM has been shown. Selectivity of the biosensors has been investigated in presence of non-complementary and one-mismatched DNA sequence.

BIBO-Stable Recursive Functional Link Polynomial Filters

The preeminent merit of linear or nonlinear recursive filters is their ability to represent unknown systems with far fewer coefficients than their nonrecursive counterparts. Unfortunately, nonlinear recursive filters become, in general, unstable for large amplitudes of the input signal. In this paper, we introduce a novel subclass of the linear-in-the-parameters nonlinear recursive filters whose members are stable according to the bounded-input bounded-output criterion. It is shown that these filters, called stable recursive functional link polynomial filters, are universal approximators for causal, time-invariant, infinite-memory, continuous, nonlinear systems according to the Stone-Weierstrass theorem. To further reduce the filter complexity, simplified structures are also investigated. Even though simplified filters are no more universal approximators, good performance is demonstrated exploiting either data measured on real systems or available in the literature as benchmarks for nonlinear system identification.

Capacity and spectrum-aware communication framework for wireless sensor network-based smart grid applications

Recently, wireless sensor networks (WSNs) have been widely recognized as a promising technology for enhancing various aspects of smart grid and realizing the vision of next-generation electric power system in a cost- effective and efficient manner. However, recent field tests show that wireless links in smart grid environments have higher packet error rates and variable link capacity because of dynamic topology changes, obstructions, electromagnetic interference, equipment noise, multipath effects, and fading. To overcome these communication challenges, in this paper, we propose a data capacity-aware channel assignment (DCA) and fish bone routing (FBR) algorithm for WSN-based smart grid applications. The proposed DCA framework deals with the channel scarcities by dynamically switching between different spectrum bands and employs a network for organizing WSN into a highly stable connected hierarchy. In addition, the proposed FBR mechanism provides robust loop free data paths and avoids high transmission cost, excessive end-to-end delay and restricts unnecessary multi-hop data transmission from the source to destination in the network. Thus, it significantly reduces the probability of data packet loss and preserves stable link qualities among sensor nodes for load balancing and prolonging the lifetime of wireless sensor networks in harsh smart grid environments. Comparative performance evaluations show that our proposed schemes outperform the existing communication architectures in terms of data packet delivery, communication delay and energy consumption.

64-GHz millimeter-wave photonic generation with a feasible radio over fiber system

A full-duplex radio over fiber (RoF) link with the generation of a 64-GHz millimeter wave (mm-wave) is investigated. This system is proposed as a solution to cope with the demands of a multi-Gb/s data transmission in the fifth generation (5G) and beyond for small cell networks. Cost reduction and performance improvement are achieved by simplifying the mm-wave generation method with an RoF technique. High-frequency radio signals are considered challenging in the electrical generation domain; therefore, our photonic generation method is introduced and examined. RoF design is proposed for mm-wave generation using both phase modulation and the effect of stimulated Brillouin scattering in the optical fiber for the first time. RoF system with transmission rates of 5 Gb/s is successfully achieved. In our scheme, one laser source is utilized and a fiber Bragg grating is used for wavelength reuse for the uplink connection. Stable mm-wave RoF link is successfully achieved in up to a 100-km fiber link length with high quality carrier. Simulation results show a reduction in fiber nonlinearity effects and the mm-wave signal has low noise equal to −75 dBm. This study ensures a practical mm-wave RoF link, and it could be appropriate for small cell 5G networks by reducing the installation cost.

Glucose oxidase immobilized on magnetic nanoparticles: Nanobiosensors for fluorescent glucose monitoring

The authors describe enzyme based nanobiosensors for continuous monitoring of glucose, with the long term goal of using them as smart diagnostic tattoos. The method is founded on two main features: (1) The fluorescence intensity and decay times of glucose oxidase (GOx) and of GOx labeled with fluorescein (FS) or a ruthenium chelate (Ru) reversibly change during interaction with glucose; (2) The (labeled) enzyme is linked to magnetite magnetic nanoparticles (MNPs) which permits the MNPs to be physically manipulated. It is found that a stable link between MNPs and GOx is only accomplished if the number of amino groups on the GOX is artificially enlarged (to form GOxsam). Fluorescence decay data are best acquired with 8-nm MNPs where scattering is marginal; The activity of GOx is found not to be affected by immobilization on the MNPs. The various immobilized enzymes (GOxsam, GOxsam-FS and GOxsam-Ru; all on MNPs) differ only slightly in terms of linear response to glucose which ranged from 0.5 mM to at least 3.5 mM. The RSDs are about 5% (for n = 5), the detection limits are at ∼50 μM, and the sensor lifetimes are >1 week.

Energy-aware and stable cluster-based multipath routing protocol for wireless ad hoc networks

Ad hoc networks are wireless networks that can operate without infrastructure and without centralised network management; they may contain nodes with limited battery power. Hence, energy conservation is a critical requirement in the design of routing protocols for ad hoc networks. Clustering has been proposed as a promising method for simplifying the routing process in mobile ad hoc networks when network size increases. In this paper, we propose an energy-efficient multipath routing protocol, called energy aware and stable cluster-based multipath routing (ES-CMR protocol), which preserves the residual energy of nodes and increases the network lifetime. To achieve this goal, we use an objective model to select energy-efficient paths with stable links. The simulation results demonstrate that ES-CMR has better performance in terms of energy consumption, network lifetime and end-to-end delay.

A Hybrid Cluster Stable Link Routing for Overhead Reduction in MANET

A Hybrid Cluster Stable Link Routing for Overhead Reduction in MANET

Improved multicast routing in MANETs using link stability and route stability

SummaryThe growing popularity of multimedia applications and services needs to support several quality of service metrics such as high throughput, low energy, and jitter, which is a challenging task in mobile ad hoc networks. Because of limited bandwidth, energy constraints, dynamic topology, transmission errors, and fluctuating link stability, the links between adjacent nodes are often not reliable and may break because of node mobility. Link breakage initiates the process of rerouting either at the sender node (the node at which the link breaks) or at the source node. In either case, it leads to packet loss, delivery delays, and increased control overheads. Hence, to attain a minimum quality of service, routing protocols must address the dynamic network topology. Uncertain and varying movement of nodes necessitates stability of the links between such nodes. The objective of this paper is to propose 2 protocols, the first based on link stability and the other based on route stability. Link stability identifies a stable link from the available links to the next hop and determines a stable end‐to‐end route. The probability of successful transmission of periodic packets is used as a link stability metric to assess the stable path. Acknowledgment ‐free packets are used to check connectivity in the network. Increased probability of successful transmission implies that the selected link is sustained for longer duration and can deliver packets more reliably or, as a consequence, results in a stable link to deliver a better data rate. With a stable link, there is a reduced possibility of retransmissions, reduced end‐to‐end delay, reduced control overheads, and enhanced data delivery ratio. Selection of the most stable route for data transmission improves the performance. Experimental results from simulations performed on EXata/Cyber v2.0 simulator reveal that our proposed protocols are an improvement over the existing protocols in terms of packet delivery ratio, average end‐to‐end delay, and average route lifetime, even without route optimization with the minor increase in control packets. A case study of the application of proposed protocols is also presented.

Difference-frequency combs in cold atom physics

Optical frequency combs provide the clockwork to relate optical frequencies to radio frequencies. Hence, combs allow to measure optical frequencies with respect to a radio frequency where the accuracy is limited only by the reference signal. In order to provide a stable link between the radio and optical frequencies, the two parameters of the frequency comb must be fixed: the carrier envelope offset frequency $f_{\rm ceo}$ and the pulse repetition-rate $f_{\rm rep}$. We have developed the first optical frequency comb based on difference frequency generation (DFG) that eliminates $f_{\rm ceo}$ by design - specifically tailored for applications in cold atom physics. An $f_{\rm ceo}$-free spectrum at 1550 nm is generated from a super continuum spanning more than an optical octave. Established amplification and frequency conversion techniques based on reliable telecom fiber technology allow generation of multiple wavelength outputs. In this paper we discuss the frequency comb design, characterization, and optical frequency measurement of Sr Rydberg states. The DFG technique allows for a compact and robust, passively $f_{\rm ceo}$ stable frequency comb significantly improving reliability in practical applications.

On the interpretation of century–millennium-scale variations of the Black Sea level during the first quarter of the Holocene

Analysis and synthesis of different paleo evidence has enabled a qualitatively new outline of the Holocene history of the Black Sea (BS). In the early Holocene, the sea level rise was complicated by a series of transgressions and regressions. The question of their origin remains open because there are no clear, stable links of the BS level anomalies and palaeohydrological phases with the calendar of climatic anomalies. Tectonically induced vertical motions may also be a source of discrepancies of different eustatic curves.Neglecting the water exchange via the Bosphorus Strait at the beginning of the Holocene, we can propose the mechanism of occurrence of large transgressive/regressive stages of the BS. The model of the BS level dynamics is interpreted as stochastic; from this perspective, it is a Langevin equation that incorporates the action of river runoff, precipitation and evaporation as random white noise. Under these conditions, the fast anomalies of the water regime are accumulated by the BS undergoing random walk. This mechanism could be responsible for the appearance of secular-millennium-scale large, irregular fluctuations of the BS level that do not correlate with known climatic events.However, such hypothetical BS level anomalies could not have occurred in the presence of a large water discharge value via the Bosphorus Strait because intensive water exchange between the BS and the Sea of Marmara was a very effective spin-down process, destroying BS level anomalies and prohibiting the development of large-scale anomalies lasting a few centuries or, furthermore, a few thousand years.Therefore, the theoretical analysis showed that the empirical data are controversial; observed BS level fluctuations during the first quarter of the Holocene and large water discharge value via the Bosphorus Sill could not occur simultaneously. The magnitude and occurrence of BS level fluctuations and features of the BS–Sea of Marmara interaction require further specification based on geological and geochronological evidence.

Fluorescence bioanalytical method for urea determination based on water soluble ZnS quantum dots

A new bioanalytical method for urea determination by using the immobilized urease on the highly luminescent ZnS quantum dots (QDs), which functioned as the pH fluorescent label has been developed. Bioconjugation of ZnS QDs to urease via amide bond was performed to obtain the ZnS QDs-urease bioconjugate. Upon enzymatic hydrolysis of urea by the immobilized urease, a pH change to a more alkaline condition has led to the deprotonation of ZnS QDs, and an increase in the fluorescence intensity can be observed. The fluorescence intensity of the urease conjugated ZnS QDs changed linearly with the urea concentrations between 4×10−9M and 4×10−3M (R2=0.992) at pH 6 with a calibration sensitivity of 179.46 intensity/decade. No noticeable influence by the Ca2+, Mg2+, K+ and Na+ ions on the response of the fluorescent pH bioprobe. Urea determination in soil sample by using the urea bioprobe was in good agreement with the standard DMAB (p-dimethylaminobenzaldehyde) UV–vis spectrophotometric method. By employing the strategy of ZnS QDs-urease bioconjugation, the stable covalent link between the two substances has appeared to widen the dynamic range and lower the detection limit for urea compared to free enzyme and QDs in solution for bioassay of urea concentration.

Neuroplastin Isoform Np55 Is Expressed in the Stereocilia of Outer Hair Cells and Required for Normal Outer Hair Cell Function.

Neuroplastin (Nptn) is a member of the Ig superfamily and is expressed in two isoforms, Np55 and Np65. Np65 regulates synaptic transmission but the function of Np55 is unknown. In an N-ethyl-N-nitrosaurea mutagenesis screen, we have now generated a mouse line with an Nptn mutation that causes deafness. We show that Np55 is expressed in stereocilia of outer hair cells (OHCs) but not inner hair cells and affects interactions of stereocilia with the tectorial membrane. In vivo vibrometry demonstrates that cochlear amplification is absent in Nptn mutant mice, which is consistent with the failure of OHC stereocilia to maintain stable interactions with the tectorial membrane. Hair bundles show morphological defects as the mutant mice age and while mechanotransduction currents can be evoked in early postnatal hair cells, cochlea microphonics recordings indicate that mechanontransduction is affected as the mutant mice age. We thus conclude that differential splicing leads to functional diversification of Nptn, where Np55 is essential for OHC function, while Np65 is implicated in the regulation of synaptic function. Amplification of input sound signals, which is needed for the auditory sense organ to detect sounds over a wide intensity range, depends on mechanical coupling of outer hair cells to the tectorial membrane. The current study shows that neuroplastin, a member of the Ig superfamily, which has previously been linked to the regulation of synaptic plasticity, is critical to maintain a stable mechanical link of outer hair cells with the tectorial membrane. In vivo recordings demonstrate that neuroplastin is essential for sound amplification and that mutation in neuroplastin leads to auditory impairment in mice.

Structural controls on Fe mineralization at Thabazimbi Mine, South Africa

Chemical-sedimentary rocks of the Transvaal Supergroup, along the northern margin of the Transvaal Basin, were imbricated during formation of the Mohlapitsi Fold-and-Thrust Belt between ca. 2.55 and 1.93Ga. High-grade (>63% Fe), stratiform Fe-ore bodies occur at or close to the base of the banded ironstone-dominated Penge Formation, which forms a distinct E-W trending mountain range in the area. The Penge Formation is separated from underlying Malmani dolostone by a thin, laterally continuous, rheologically-weak, carbonaceous shale layer that has been intensely sheared. This horizon denotes the position of a regional, top-to-N, low-angle detachment that has been variably deformed during progressive development of the Mohlapitsi Belt. Several of Kumba's Thabazimbi iron ore deposits, including Kwaggashoek East, Donkerpoort West, Kumba-Donkerpoort West and Buffelshoek West, are confined to a zone directly above this detachment. Recent studies of ore petrography, fluid alteration, fluid composition and stable isotope geochemistry link economic iron ore mineralization to hydrothermal or hypothermal processes. Along with localized high-grade mineralization, a structural control on fluid flow has been suggested, although a lack of structural data has hampered more concise mineralization models thus far. In this study we present and analyse data from detailed structural mapping over a protracted period of mining, across four opencast pits. This mapping is combined with drillhole data to produce accurate, intergrated 3D models of these deposits, which reveal the true geometry of these ore bodies.Data and resultant models indicate that enhanced hydrothermal fluid flow associated with significant iron mineralization is linked to thrusting/shearing in response to: 1) fold amplification and flexural flow along the E-W trending detachment between the Malmani dolostone and banded iron formation; 2) subsidiary fold-accommodation structures such as conjugate shear joints, normal and reverse faults and thrusts, associated with inner- and outer-arc shortening and extension, respectively; 3) localization of Fe at the intersections of major reverse faults, the detachment and stratigraphically-higher, low-angle thrusts, which are preferentially developed at the contacts between diabase and banded iron formation. Collectively, these features both aided and compartmentalized regional, pervasive fluid flow along the detachment and in stratigraphically-higher sites. Subsequent ore preservation was enhanced by reactivation of NW- to NNW-trending, Mesozoic normal faults and concomitant downthrow of fault-bounded blocks. Structural relationships and timing of high-grade iron ore mineralization further suggest that associated top-to-N kinematic fold-and-thrust formation of the Mohlapitsi Belt and, subsequently, the main detachment between Malmani dolostone and banded iron formation of the Penge Formation, could have been active during and immediately after intrusion of the Bushveld Complex at ca. 2.05Ga.

Dynamical complexity in the perception-based network formation model

Many link formation mechanisms for the evolution of social networks have been successful to reproduce various empirical findings in social networks. However, they have largely ignored the fact that individuals make decisions on whether to create links to other individuals based on cost and benefit of linking, and the fact that individuals may use perception of the network in their decision making. In this paper, we study the evolution of social networks in terms of perception-based strategic link formation. Here each individual has her own perception of the actual network, and uses it to decide whether to create a link to another individual. An individual with the least perception accuracy can benefit from updating her perception using that of the most accurate individual via a new link. This benefit is compared to the cost of linking in decision making. Once a new link is created, it affects the accuracies of other individuals' perceptions, leading to a further evolution of the actual network. As for initial actual networks, we consider homogeneous and heterogeneous cases. The homogeneous initial actual network is modeled by Erd\H{o}s-R\'enyi (ER) random networks, while we take a star network for the heterogeneous case. In any cases, individual perceptions of the actual network are modeled by ER random networks with controllable linking probability. Then the stable link density of the actual network is found to show discontinuous transitions or jumps according to the cost of linking. As the number of jumps is the consequence of the dynamical complexity, we discuss the effect of initial conditions on the number of jumps to find that the dynamical complexity strongly depends on how much individuals initially overestimate or underestimate the link density of the actual network. For the heterogeneous case, the role of the highly connected individual as an information spreader is discussed.