Asymmetric Communication Research Articles

Choreographies and Behavioural Contracts on the Way to Dynamic Updates

We survey our work on choreographies and behavioural contracts in multiparty interactions. In particular theories of behavioural contracts are presented which enable reasoning about correct service composition (contract compliance) and service substitutability (contract refinement preorder) under different assumptions concerning service communication: synchronous address or name based communication with patient non-preemptable or impatient invocations, or asynchronous communication. Correspondingly relations between behavioural contracts and choreographic descriptions are considered, where a contract for each communicating party is, e.g., derived by projection. The considered relations are induced as the maximal preoders which preserve contract compliance and global traces: we show maximality to hold (permitting services to be discovered/substituted independently for each party) when contract refinement preorders with all the above asymmetric communication means are considered and, instead, not to hold if the standard symmetric CCS/pi-calculus communication is considered (or when directly relating choreographies to behavioral contracts via a preorder, no matter the communication mean). The obtained maximal preorders are then characterized in terms of a new form of testing, called compliance testing, where not only tests must succeed but also the system under test (thus relating to controllability theory), and compared with classical preorders such as may/must testing, trace inclusion, etc. Finally, recent work about adaptable choreographies and behavioural contracts is presented, where the theory above is extended to update mechanisms allowing choreographies/contracts to be modified at run-time by internal (self-adaptation) or external intervention.

Modulated retroreflector based on metallic nanoshells for applications in the visible band

In our research, we have theoretically studied a device that can serve as a modulating retroreflector (MRR) for applications in the visible spectrum. The device is comprised of a nanocomposite of a ferroelectric thin-film embedded with noble metal nanoshells. In comparison to the nanospheres, the nanoshells provide more flexibility in the design of the device. This MRR can be used in asymmetric communication links as an optical transceiver for mobile devices. The main conclusion from our study is that a nanocomposite-based MRR can save power, complexity, dimensions, and weight in comparison to standard communication links. This fact is very important for mobile platforms.

Rhetorical framing: examining the message structure of nonprofit organizations on Twitter

All organizations must persuade stakeholders that they are worth supporting. Organizations need donors to give, volunteers to volunteer, consumers to purchase, and general support for public funding. Because Twitter messages are restricted to 140 characters or less, organizations' message structures must be clearer and may employ traditional rhetorical techniques such as ethos, pathos, and logos, to garner support and promote action. By using content analysis, the tweets of eight charitable organizations from diverse sectors were analyzed for rhetorical content, type of communication such as two‐way symmetrical or two‐way asymmetrical communication, and positive or negative message frame, for one calendar month. Results of this study found that 60% of tweets employed rhetorical strategy and the majority of tweets included a positive message frame. Moreover, each of the three broad functional areas defined by Lovejoy and Saxton (2012) used ethos, pathos, and logos to differing degrees. Based on results, proposed expansions of the functional areas are also discussed. Copyright © 2014 John Wiley & Sons, Ltd.

Study on the Informatization of Renewable Resources Industry

As we all know that the renewable resources industry (RRI) is booming in China, while there are many problems too. The paper put forwards that one of the important reason resulting in these problems is that informatization lags behind the RRI informatization process. Asymmetric information and poor communication restricted the development of the RRI. Based on the Characteristics of China’s RRI, The paper analyzes the asymmetric information models in RRI, discusses the information technology experience used in the RRI. Finally, and also, a case of recycling resources information Database system was introduced.

Asymmetric communication models for resource‐constrained hierarchical ethernet networks

SummaryCommunication time prediction is critical for parallel application performance tuning, especially for the rapidly growing field of data‐intensive applications. However, making such predictions accurately is non‐trivial when contention exists on different components in hierarchical networks. In this article, we derive an ‘asymmetric network property’ on transmission control protocol (TCP) layer for concurrent bidirectional communications in a commercial off‐the‐shelf (COTS) cluster and develop a communication model as the first effort to characterize the communication times on hierarchical Ethernet networks with contentions on both network interface card and backbone cable levels. We develop a micro‐benchmark for a set of simultaneous point‐to‐point message‐passing interface (MPI) operations on a parametrized network topology and use it to validate our model extensively and show that the model can be used to predict the communication times for simultaneous MPI operations (both point‐to‐point and collective communications) on resource‐constrained networks effectively. We show that if the asymmetric network property is excluded from the model, the communication time predictions will be significantly less accurate than those made by using the asymmetric network property. In addition, we validate the model on a cluster of Grid5000 infrastructure, which is a more loosely coupled platform. As such, we advocate the potential to integrate this model in performance analysis for data‐intensive parallel applications. Our observation of the performance degradation caused by the asymmetric network property suggests that some part of the software stack below TCP layer in COTS clusters needs targeted tuning, which has not yet attracted any attention in literature. Copyright © 2014 John Wiley & Sons, Ltd.

Orthogonal projection based asymmetric multi‐way relaying with antenna subset selection

An asymmetric multi-way relay communication scheme using orthogonal projection and analogue network coding is proposed. The scheme is designed for the wireless sensor network, where one sink node (SN) exchanges information with multiple user nodes via a relay station and both the SN and user nodes have low complexity structures. It has been observed that the minimal number of the relay antennas can be smaller than that of the total data streams. Moreover, when the number of the relay antennas is larger than the minimum, a paired throughput based max–min criterion with low computational complexity is developed to select the optimal relay antenna subset and guarantee full diversity gain. The numerical results demonstrate the high performance of the proposed communication scheme and antenna subset selection criterion.

Tracking consensus of nonlinear MASs with asymmetric communication delays in noisy environments

This paper investigates the tracking consensus problem of nonlinear multi-agent systems (MASs) with asymmetric time-varying communication delays in noisy environments under the conditions of fixed and switching directed topologies. A novel stochastic analysis approach is proposed, which guarantees that the designed two distributed tracking protocols can guide the controlled systems to achieve tracking consensus in the sense of mean square. In order to further reveal the influence of asymmetric communication delays on the tracking consensus ability for MASs, some new delay-dependent sufficient conditions for mean-square consensus are also developed. A simple example is finally given to illustrate the effectiveness of the proposed theoretical results.

Performance analysis of energy efficient modulation and coding schemes for wireless sensor networks

Sensor nodes of a typical wireless sensor network (WSN) are battery driven, so energy conservation is a critical factor for node's life time. Thus optimisation of energy consumption is a major objective in the area of WSNs. One such method is asymmetric communication which uses different channel codes and modulation schemes for downlink (base station (BS) to node link) and uplink (node to BS link). In this paper, a performance analysis of different channel code–modulation pair for energy efficient asymmetric communication is carried out followed by the field programmable gate array implementation of channel codes required at the node. The per information bit node energy for the uplink has been calculated for efficient channel code–modulation pair, for three different channels, viz. additive white gaussian noise, Rayleigh flat-fading and log-normal shadowing channels, resulting in reduction in energy consumption at sensor nodes.

IMPROVING THE EFFECTIVENESS OF SMALL-HOLDER FARM POSTHARVEST PRACTICES IN FIJI

This paper outlines current postharvest handling practices of five vegetables supply chains in Viti Levu, the Fiji Islands. Domestic-orientated chains involved characteristically low-input production systems, had limited postharvest infrastructure (packing sheds, cool rooms and grading equipment) and reflected inadequate grower and trader postharvest handling knowledge and expertise. Domestic supply chains are often short, with poor and asymmetric communications, discontinuous transport logistics and ineffective postharvest disease-management the major contributors to postharvest losses. Paradoxically, while increasing farm size tended to reflect greater professionalism of production practices, this did not translate to concurrent improvements in postharvest handling. Export-orientated chains involve a much more structured approach to postharvest handling, based on trader and exporter-led interventions. Product consignments are sourced from a large number of growers, graded and packed in a central pack-house and held under cool storage prior to transport. Aspects of a quality management system are evident, with some traders also providing a support services to their contracted growers to improve product quality and supply uniformity.

A UHF/UWB hybrid silicon RFID tag with on–chip antennas

In this contribution, we describe and analyse a miniature wireless radio frequency identification (RFID) chip with on-chip antennas (OCA) and ultra wideband (UWB) signalling by real-world measurements. With the on-chip antenna approach, no external antennas are required, and the size of the overall tag is identical to the size of the chip alone (3.5 mm×1 mm). The chip is powered through inductive coupling and controlled by an RFID signal at 866 MHz in the downlink, while the uplink transmits a quaternary pulse-position-modulated (4-PPM) UWB signal at 5.64 GHz with pulses having a duration in the order of nanoseconds. In this contribution, the hybrid or asymmetric communication scheme between prototype chip and reader, the embedded OCA, and the measurement setup are described. The prototype achieves 4-PPM bit rate of 126 Mbit/s based on a pulse-train transmission with a duration of 10 μs. The small size, high data rate, and fine time resolution of the UWB impulse radio offer new features and sensing capabilities for future RFID-like applications.

Aligning Mental Representations

This work introduces a framework that implements asymmetric communication theory proposed by Sperber and Wilson [1]. The framework applies a generalization model known as the Bayesian model of generalization (BMG) [2] for aligning knowledge possessed by two communicating parties. The work focuses on the application of the BMG to publicly available datasets, the Leuven natural concept database [3] representing semantic structures of domain knowledge possessed by individual subjects [3]. Results indicate that the BMG is potentially a model applicable to simulating the alignment of domain knowledge from the information receiver’s viewpoint.

A topology-aware load balancing algorithm for clustered hierarchical multi-core machines

In this paper, we present a topology-aware load balancing algorithm for parallel multi-core machines and its proof of asymptotic convergence to an optimal solution. The algorithm, named HwTopoLB, aims to improve the application performance by reducing core idleness and communication delays. HwTopoLB was designed taking into account the properties of current parallel systems composed of multi-core compute nodes, namely their network interconnection, and their complex and hierarchical core topology. The latter comprises multiple levels of cache, and a memory subsystem with NUMA design. These systems provide high processing power at the expense of asymmetric communication costs, which can hamper the performance of parallel applications depending on their communication patterns if ignored. Our load balancing algorithm models asymmetries in terms of latencies and bandwidths, representing the distances and communication costs among hardware components. We have implemented HwTopoLB using the Charm++ Parallel Runtime System and evaluated its performance with two different benchmarks and one application. Our experimental results with HwTopoLB exhibit scalability over clustered multi-core compute nodes, and average performance improvements of 23% over execution without load balancers and 19% over the existing load balancing strategies on different multi-core systems.

Worst-case asymmetric distributed function computation

We consider a distributed function computation problem where an information sink communicates with N correlated information sources to compute a given deterministic function of source data. A data-vector is drawn from a discrete and finite probability distribution and component x i is revealed to ith, , source. We address this problem in asymmetric communication scenarios where only the sink knows the distribution P. We are interested in computing the minimum number of source bits required, in the worst-case, to solve this problem. We propose the notion of functional ambiguity to carry out the worst-case information-theoretic analysis of distributed function computation problems. We establish its various characteristics and prove that it leads to a valid information measure. Then, we provide a constructive solution for the distributed function computation problem in terms of an interactive communication protocol and prove its optimality. Finally, we establish two equivalence classes of compressible and incompressible functions to classify the set of all computable multivariate functions based on the minimum number of source bits needed in the worst-case to compute a function in the distributed function computation set-up.

Control of semi-autonomous teleoperation system with time delays

In teleoperation systems operating in complex environments, due to the cognitive limitations of the human operator and lack of complete information about the remote environment, safety and performance of such systems can potentially be comprised. In order to ensure the safety and enhance the efficiency of complex teleoperation systems operating in cluttered environments, in this paper we investigate a semi-autonomous control framework for bilateral teleoperation. The semi-autonomous teleoperation system is composed of heterogeneous master and slave robots, where the slave robot is assumed to be a redundant manipulator. Considering robots with different configurations, and in the presence of dynamic uncertainties and asymmetric communication delays, we first develop a control algorithm to ensure position and velocity tracking in the task space. Additionally in the absence of dynamic uncertainty, and in the presence of human operator and environmental forces, all signals of the proposed teleoperation system are proven to be ultimately bounded. The redundancy of the slave robot is then utilized for achieving autonomous sub-task control, such as singularity avoidance, joint limits, and collision avoidance. The control algorithms for the proposed semi-autonomous teleoperation system are validated through numerical simulations on a non-redundant master and a redundant slave robot.

The Articulation of Massmedia and Social Media: Exploring civic movements in Portugal

Each time a new communication medium is introduced and reaches relative generalization, it creates new balances and articulations among the existing media, thus reconfiguring the whole mediatic and communicational landscape (Bolter and Grusin, 2000; Jenkins, 2006). In contemporary society, two types of media with totally different characteristics and op - erating logics coexist, articulate and converge among themselves � massmedia and social media � resulting in a new way of communicating, describes by Manuel Castells (2009) as mass-self communication. Within public relations, several authors recognize a transition from asymmetric communica - tion theories and models, in which organizations publicize information a strongly control their messages, to more symmetric conversation and dialogic models that are emerging as a consequence of PR professionals using social media as communication channels and tools (Kunsch, 2003; Solis and Breakenridge, 2009; Scott, 2010; Macnamara and Zerfass, 2012). Although most of these authors highlight the loss of control over their messages that or - ganizations are undergoing, others explore the emergence of new power balances that are not necessarily symmetric or equalitarian (Edwards and Hodges, 2001; Coombs and Holladay, 2012; Dutta, Ban and Pal, 2012). This paper explores civic movements as an example of the new articulations among mass - media and social media that emerging, as well as new power balances between the public, media and politic agendas (McCombs and Shaw, 1972). Using qualitative methods, this paper empirically explores the recent civic movements against austerity in Portugal, that culminated with the demonstrations �Geracao a Rasca� [�Precarious� Generation] (12th March 2011) and �Que se lixe a Troika!: Queremos as nossas vidas� [Screw Troika! We want our lives back] (15th September 2012), discussing the articulation of massmedia and social media that was done both by citizens and communication professionals (PRs and journalists, as well the rol

Heuristic algorithm based on multicriteria analysis for selection of first mile access in standard integrated services digital broadcasting terrestrial

Technologies used to link the end-user to a telecommunication infrastructure have been growing over time because of the consolidation of new access technologies. Moreover, the arrival of new tools for information dissemination, such as interactive digital TV, creates a bidirectional element, capable of connecting the end-user to telecommunications networks through access technologies such as worldwide interoperability for microwave access, 3G, asymmetric digital subscriber line and power line communication. This study presents a heuristic based on multicriteria analysis for selection of first mile access in the integrated services digital broadcasting terrestrial standard, ensuring quality of service, using a videoconferencing application as an example. The following analytical approaches, with multicriteria analysis, are presented towards decision making for televisions connected to more than one return channel: (a) fuzzy AHP for defining the criteria weights (delay, jitter, throughput, packet loss etc.); (b) technique for order preference by similarity to ideal solution (TOPSIS) method, for approximation, guided by measurements taken in real scenarios; (c) elimination and choice translating reality III method, used to ranking the alternatives and comparing with TOPSIS.

The effect of osteocyte apoptosis on signalling in the osteocyte and bone lining cell network: a computer simulation

Osteocytes play a critical role in the regulation of bone remodelling by translating strain due to mechanical loading into biochemical signals transmitted through the interconnecting lacuno-canalicular network to bone lining cells (BLCs) on the bone surface. This work aims to examine the effects of disruption of that intercellular communication by simulation of osteocyte apoptosis in the bone matrix. A model of a uniformly distributed osteocyte network has been developed that simulates the signalling through the network to the BLCs based on strain level. Bi-directional and asymmetric communication between neighbouring osteocytes and BLCs is included. The effect of osteocyte apoptosis is examined by preventing signalling at and through the affected cells. The simulation shows that apoptosis of only 3% of the osteocyte cells leads to a significant reduction in the peak signal at the BLCs. Furthermore, experiments with the model confirm how important the location and density of the apoptotic osteocytes are to the signalling received at the bone surface. With 5% and 9% osteocyte apoptosis, the mean peak BLC levels were reduced by 25% and 37% respectively. Such a significant reduction in the signal at the BLCs may explain a possible mechanism that leads to the increased remodelling and eventual bone loss observed with osteoporosis. More generally, it provides a unique framework for a broader exploration of the role of osteocyte and bi-directional and asymmetric cell–cell communication in mechanotransduction, and the effects of disruption to that communication.

A state-based model of sensor protocols

We introduce a state-based model that can be used in specifying and verifying the desired properties of sensor network protocols. This model accommodates several characteristics that are common in sensor networks. Examples of these characteristics are unavoidable local broadcast, probabilistic message transmission, asymmetric communication, message collision, and timeout actions and randomization steps. We also propose three methods for analyzing a sensor network protocol specified in the model. In the first method, called nondeterministic analysis, a specified sensor network protocol is shown to be “nondeterministically correct” under the assumption that message delivery is assured and message collision is guaranteed not to occur. In the second method, called probabilistic analysis, the protocol is shown to be “probabilistically correct” under the assumption that message delivery is probabilistic but message collision is guaranteed not to occur. In the third method, called collision analysis, the effect of message collision and probabilistic message delivery on the correctness of the protocol is analyzed. To demonstrate the utility of our model, we discuss an example protocol that can be used by a sensor to identify its strong neighbors in the network, and apply the analysis methods to the protocol. Using our model, we also show that the protocol satisfies a desirable property, called self-stabilization property.

Comment on: Supervisory Asymmetric Deterministic Secure Quantum Communication

In 2010, Xiu et al. (Optics Communications 284:2065–2069, 2011) proposed several applications based on a new secure four-site distribution scheme using χ-type entangled states. This paper points out that one of these applications, namely, supervisory asymmetric deterministic secure quantum communication, is subject to an information leakage problem, in which the receiver can extract two bits of a three-bit secret message without the supervisor’s permission. An enhanced protocol is proposed to resolve this problem.

Cooperative Multiuser Relay Communications Employing Hierarchical Modulation

Relay-assisted cooperative communications are a promising solution for error-performance improvement and cell coverage extension. However, additional resources such as time slots or frequency bands are required for the relay, which reduce the overall throughput. This paper proposes two cooperative relay schemes that employ hierarchical modulation to overcome this limitation. One scheme is for symmetric downlink communications and the other is for asymmetric downlink communications. These schemes exploit the hierarchical modulation symbols for users in the network and allow the system to transmit two or more independent data streams simultaneously. The proposed schemes reduce the number of transmission phases to the same as conventional schemes without diversity gain. The symbol-error rates of the proposed systems are a function of the distance parameter of hierarchical modulation. By flexibly controlling the distance parameter based on specific scenarios, it allows an extra degree of freedom to guarantee error performance of receivers whose signals undergo different losses.