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This paper introduced new method and model of telecommunication switching system design which can be applied to wavelength-division multiplexing (WDM) optical networks, circuit-switching networks or virtual channel/path connections in an asynchronous transfer mode (ATM) networks. Modern data switching systems such as electronic private branch exchange (PBX), routers and switches include switching matrix which are constructed in the form of bipartite graphs. In such systems, the issues of requests' processing are considered from the queuing theory point of view. Associative switching systems are fundamentally new structures, therefore it is necessary to develop adequate methods for their throughput determination. Article covered matters of throughput determination basics of an associative switching system and the obtained formulas used for state probability calculation of switching modules and system throughput. [ABSTRACT FROM AUTHOR]

The construction of a sustainable transport network for people or goods will gain and harm mobility depending on their nature and implementation, using new technology and business models. The regular mobile handoff and replacement of connections allow the efficient mobility management of asynchronous wireless transfer mode (ATM) networks. Hence, the design of the broad spectrum usability network architecture for public ATM systems has been given considerable attention in the literature. Since it has been done on the critical subject of estimating user mobility and the prediction, which aims to improve communication efficiency and the bandwidth efficiency of the underlying system architecture, this article addresses the problem by developing the impact of hierarchical framework of service on transportation and traffic pattern (HFSTTP). The growth in mobile Internet and the use of mobile devices over the last decade allowed for omnipresent information on traffic. With the growing use of unique mobile apps, the number of routing users has evolved to be sufficiently large to interrupt the traffic flow pattern. Modern carriage systems and urban logistics improve the efficiency of the transport of goods and slow down the use of road infrastructure. Numerical examples of vehicle traffic include proof of ties between the network traffic and the routing decision‐making layer. The partnership between a cooperative control layer and a lower control layer to optimize freight transport is a second example. The congestion price in all over the world shows how to incorporate the social plan layer in future mobility services. [ABSTRACT FROM AUTHOR]

The flux, speed, and torque control performance of asynchronous motors are affected by parameter deviations and nonlinear variations of the asynchronous motor. In this study, Direct Torque Control (DTC) and Indirect Field Oriented Control (IFOC) structures are examined and asynchronous motor parameter deviations in both control structures are varied to desensitize with Artificial Neural Networks (ANN). In the literature, PI controllers are used in the IFOC structure. ANN is proposed for parameter desensitization, to the best of our knowledge no comparison and assessment has been made in the literature for these two methods. Comparisons are usually on the Direct Field Oriented Control (DFOC). This study proposes the parameter desensitization of IFOC and DTC with / without artificial neural networks and examines the effect on output performance. With the proposed control structure, it has been observed that the values of flux, torque and speed of asynchronous motor outputs capture the reference value at the desired performance and decrease the error values. With the proposed desensitization with ANN, IFOC performed over 50% better particularly in the time of overshoot and sitting than DTC. The proposed algorithms are implemented with Matlab / Simulink and the same reference values are used for each method. [ABSTRACT FROM AUTHOR]

The Hobbs Act, passed by Congress in 1946, makes it a federal crime to obstruct, delay, or affect commerce through robbery or extortion. "Commerce" is the federal jurisdictional hook that elevates robbery to a federal crime. The commerce hook grants jurisdiction for all robberies that Congress's Commerce Clause power reaches. This Note argues that federal Hobbs Act robbery prosecutions for individual, localized robbery eviscerates meaningful dual federalism distinctions and has led to confusion among lower courts and patchwork definitions for what it means to "affect commerce" for these cases. This Note proposes three solutions--at least one for each coordinate branch of government--to solve the problem. For the judicial branch, the Supreme Court should declare the Hobbs Act unconstitutional because it grants Congress a police power to reach purely local robbery that should be left to state prosecution and that "commerce" should be interpreted consistently with its meaning at the time of the Hobbs Act's passage. For the legislative branch, Congress should amend the Hobbs Act to only allow federal prosecution of robberies that "substantially and directly" affect commerce. The Note concludes that the judicial and legislative solutions for Hobbs are unlikely, so pragmatically, the executive branch should adopt prospective enforcement policies that make clear Hobbs charges should not be brought for de minimis, localized robbery. Each of these solutions would aid in restoring the appropriate balance between federal and state criminal robbery law thus, keeping federal resources trained on the most pressing national concerns. [ABSTRACT FROM AUTHOR]

In the bid to bring about a solution to the nagging problem associated with the provision of ubiquitous broadband access, Next Generation Network (NGN) popularly referred to as Long Term Evolution (LTE) network with appropriate network integration technique is recommended as solution. Currently, Internet Protocol/Multi-Protocol Label Switching (IP/MPLS) is the transport technique in LTE backbone infrastructure. This technique, however, suffers significantly in the event of failure of IP path resulting in delay and packet loss budgets across the network. The resultant effect is degradation in users quality of service (QoS) experience with real-time services. A competitive alternative is the Internet Protocol/Asynchronous Transfer Mode (IP/ATM). This transport technique provides great dynamism in the allocation of bandwidth and supports varying requests of multimedia connections with diverse QoS requirements. This paper, therefore, seeks to evaluate the performance of these two transport techniques in a bid to establish the extent to which the latter technique ameliorates the aforementioned challenges suffered by the previous technique. Results from the simulation show that the IP/ATM transport scheme is superior to the IP/MPLS scheme in terms of average bandwidth utilization, mean traffic drop and mean traffic delay in the ratio of 9.8, 8.7 and 1.0% respectively. [ABSTRACT FROM AUTHOR]

We performed high-level quantum mechanical calculations and direct ab initio reaction dynamics calculations for multiple proton transfers in ClONO2+HCl→HNO3+Cl2 with water clusters containing one to two water molecules, which can be used as a model of the reactions occurring on ice surface in stratospheric clouds. The energy barriers of these reactions depend on the number of water molecules involved. Two and three protons in these reactions with one and two water molecules, respectively, were transferred concertedly and asynchronously. The potential energy barrier at the MP2/6-311++(3df,3pd)//MP2/6-31G(d,p) level was 4.8 kcal/mol for the triple proton transfer involving two water molecules with a rate constant of 1.6×103 s-1 at 197 K. The potential energy curve near the saddle points was very flat and the tunneling effect on the proton transfer was negligible. The primary HH/DH kinetic isotope effect for the double proton transfer involving one water molecule was lower than unity due to the enhanced force constant at the transition state. The rule of the geometric mean for the concerted proton transfer does not hold in these reactions because the zero-point energy changes of each proton in flight at the transition state are not the same in the highly asynchronous processes. [ABSTRACT FROM AUTHOR]

In existing works, accurately analyzing human activities is a complicated problem in public places. Consequently, the detection of human activities becomes challenging the computer vision technology. The major scope of the research is to develop an abnormal Human Activity Recognition (HAR) model using deep structured architectures for detecting the suspicious activities of humans in the ATM using the video surveillance system. The classification phase utilizes the enhanced deep learning approach named improved Long Short-Term Memory (LSTM) by optimizing certain parameters in LSTM by hybrid optimization algorithm for accurately classifying the normal and abnormal activities of humans. This hybrid optimization algorithm is developed and termed Hybrid Spider Monkey-Chicken Swarm Optimization (HSM-CSO) for achieving the effective performance of the deep learning-based classification. Hence, the designed HAR model in ATM is proven that it helps to improve the system performance and also give relief from prohibited activities or crimes and false alarms for humans. [ABSTRACT FROM AUTHOR]

This research proposes a method that generates viewpoint smooth switching by reducing the flickering artefacts that are observed at bullet-times generated from asynchronous multi-view videos using frame interpolation processing. When we asynchronously capture multi-view videos of an object moving at a high velocity, deviations occur in the observed position at the bullet-times. We apply a frame interpolation technique to smooth this problem. By selecting suitable interpolated images that produce the smallest movement of the subject's observed position, we smoothly generate a viewpoint-switched bullet-time video. In this paper, we examine the subjective evaluation of the video generated by the proposed method. And we also examine objective evaluation. Therefore, the effectiveness of the proposed method is shown. Furthermore, reproducibility was improved by considering the application conditions of the proposed method. [ABSTRACT FROM AUTHOR]

Abstract Recently, the finger-vein (FV) trait has attracted substantial attentions for personal recognition in biometric community, and some FV-based biometric systems have been well developed in real applications. However, improving the efficiency of FV recognition over a large-scale database remains a big practical problem. Moreover, unreliable finger-vein region of interest (ROI) localization and venous region enhancement can also heavily degrade the performance of a finger-vein based recognition system in practical scenario. In this paper, we first propose some new methods in FV ROI extraction and enhancement, and then an efficient and powerful hierarchical hyper-sphere model (HHsM) is developed based on granular computing (GrC). For HHsM construction, FV image samples from a given FV database are first converted into atomic granules for primary hyper-sphere granule set generation, and then some coarsened granule sets with different granularity levels are born by hyper-sphere granulation. Considering recognition efficiency improvement, a new hierarchical relationship among the coarsened granule sets is established to structure them level-wisely. Experimental results demonstrate that the proposed methods perform very well in handling ROI extraction, venous region enhancement and FV recognition. [ABSTRACT FROM AUTHOR]

We study the problem of frame synchronization over a discrete memoryless channel (DMC) in an asynchronous setup. A sync frame is transmitted at a random time $V$ with a known distribution $\{a_{v} \}$ and entropy $H$. We seek to characterize the minimum average length or energy of the sync frame necessary for error-free frame synchronization, as $H$ tends to infinity. We present a variable length sync frame, where the length of the sync frame is adapted based on $H$ and $\{a_{v} \}$ , for the general arrival distribution and show error-free frame synchronization when the average sync frame length $\bar {N}$ scales as $\Omega (({H}/{\alpha (Q)})$ , where $\alpha (Q)$ is the synchronization threshold of the DMC. We then generalize the framework and study a tradeoff between $\bar {N}$ and $\alpha (Q)$ for optimal frame synchronization and characterize the scaling needed of both $\bar {N}$ and $\alpha (Q)$ with $H$. We illustrate our results with the AWGN channel and discuss the adapting sync frame length and symbol power for optimal frame synchronization. Finally, using numerical work and simulations, we evaluate the results under relaxed assumptions, including the imperfect knowledge of arrival distribution and symbol timing error. [ABSTRACT FROM AUTHOR]

This paper is concerned with the event-triggered finite-time control problem for networked switched linear systems by using an asynchronous switching scheme. Not only the problem of finite-time boundedness, but also the problem of input-output finite-time stability is considered in this paper. Compared with the existing event-triggered results of the switched systems, a new type of event-triggered condition is proposed. Sufficient conditions are established to guarantee the event-based asynchronous closed-loop systems are both finite-time bounded and input-output finite-time stable. A set of event-triggered finite-time bounded and input-output finite-time stabilizing controllers are designed under the asynchronous control scheme. It is revealed that the triggered thresholds determine the number of sampling points transmitted to the controller, and the smaller triggered parameters indicate the less-sampled data needed to be transmitted to the controller under the event-triggered scheme. Finally, a boost converter circuit is applied to bring out the advantages of the proposed control scheme. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates the effect of asynchronous earthquake ground motion on the transverse response of base-isolated bridges. In this context, the excitation of anti-symmetric modes of vibration under asynchronous input is examined and is statistically correlated with characteristic engineering demand parameters. Different ground motion scenarios are considered for various combinations of soil class, wave propagation velocity and loss of correlation patterns among different support motions, using a spectral representation method to generate m-variate, fully non-stationary, EC8 spectrum-compatible ground motion vector processes. It is shown that in the idealised case of the wave passage effect only, the detrimental effects of asynchronous excitation are concentrated on the very last piers along the direction of the seismic waves. However, when loss of coherency is also taken into account in a more realistic scenario, the impact of spatial variability is significantly more uniformly distributed. Most importantly, the conditional probability of a detrimental increase in an EDP of interest (i.e., pier base bending moments and deck drift) under multi-support excitation given that an anti-symmetric mode is excited is not only uniform but also considerably high. This is a clear evidence that the local increase of seismic demand in the bridge studied is associated with the excitation of the first anti-symmetric mode of vibration. Highlights • Excitation of anti-symmetric modes under asynchronous seismic motion is investigated. • Synthetic fully non-stationary EC8 spectrum compatible ground motions are generated. • The excitation of higher modes is key in increasing seismic demand. [ABSTRACT FROM AUTHOR]

This paper studies the problem of determining sensor locations in a large sensor network using only relative distance (range) measurement. Based on the barycentric coordinate representation, we propose a totally asynchronous distributed algorithm under DILOC framework due to independence of sensor update instants and unreliable networks with communication delays and packet losses. Through modeling the asynchronous algorithm as a linear difference equation with time-varying delays, we prove that the location estimates of sensors are globally convergent to the true coordinates if: (1) time interval between any two consecutive update instants is bounded from below and above, (2) communication delays and successive packet losses between sensors are finite. Simulation examples are provided to demonstrate the effectiveness of the theoretical result. [ABSTRACT FROM AUTHOR]

This paper investigates the asynchronous H ∞ filtering problem for discrete-time switched systems under dwell time constraint and missing measurements. Based on the proposed dwell-time-dependent Lyapunov function (DTDLF) technique, a novel switching strategy consisting of a time-dependent mechanism and a state-dependent switching mechanism is constructed, such that the resultant filtering error systems are exponentially mean square stable with a weighted l 2 -gain performance. In addition, the value of the DTDLF is allowed to increase at both the unmatched interval and switching instants. The desired dwell-time-dependent asynchronous H ∞ filter is designed in forms of linear matrix inequalities. More incisively, the proposed method is also applicable to switched systems with unstable subsystems. Finally, three simulation examples are provided to illustrate the effectiveness and potential of the developed results. [ABSTRACT FROM AUTHOR]

Highlights • The asynchronous double beam detection method is used for gas sensing. • The derivative of absorption spectroscopy is extracted. • Absorbance of ammonia is recovered from the integration of the first-order derivative. • Derivative of absorption is created without modulating the lasing injection current. Abstract In this paper, we report on the utilization of a novel background-free approach for trace gas sensing. The classical collocation of wavelength modulation spectroscopy and phase sensitive detection is replaced by asynchronous double beam structure in which a balanced amplified photodetector is introduced. Via a beam splitter, the laser beam passing through the gas medium is divided into the real-time and the delayed branches. An optic fiber delay line is taken to create a time-delay between the separated branches, and the following differential detection yields the first derivative of absorption spectrum that is equivalent to the first harmonic in wavelength modulation spectroscopy. By means of the straightforward method, the quantitative analysis of gas is performed without the disturbance that is caused by optical intensity modulation. The gas sensor is validated using ammonia and nitrogen mixture in a laboratory controlled environment (296 K in temperature and 1.01e5 Pa in total pressure). In the case of an absorption path with the effective length of 15.4 cm, the detection limit of 6.4 ppm is predicted from the assumption that the signal is weakened to be equal with the noise. Absorption spectroscopy for 500 ppm ammonia is recovered by integrating the output of balanced photodetector. [ABSTRACT FROM AUTHOR]

In this paper, an adaptive inter-track interference (ITI) mitigating scheme is proposed for interlaced magnetic recording (IMR) with random frequency offsets. Recently, proposed IMR has a potential areal density capability gain over conventional perpendicular magnetic recording, as it involves writing tracks with differentiated linear densities in an interlaced manner, while suppressing the ITI efficiently during the reading operation via asynchronous ITI cancellation (A-ITIC). The A-ITIC estimates and subtracts the ITI contributions from its side tracks in the effectively synchronized domain via interpolation-filter-based relative timing adjustments. However, when the tracks are recorded with non-negligible random frequency offsets, the ITI response is averaged out, providing a weak estimate, and the A-ITIC-based bit error rate performance gain disappears. In order to compensate for these dynamic timing misalignments, an adaptive ITI mitigation scheme is proposed called an adaptive A-ITIC, where the ITI response is continuously updated via effective timing adjustments along the sector. Numerical evaluations using a micro-pixel-based magnetic channel model show that the legacy A-ITIC performs poorly for IMR with non-negligible random frequency offsets, whereas the proposed adaptive scheme compensates for most of the performance degradation by effectively tracing the relative timing shifts via adaptation measures. [ABSTRACT FROM AUTHOR]

Current trends and projections show that faults in computer systems become increasingly common. Such errors may be detected, and possibly corrected transparently, e.g., by Error Correcting Codes (ECC). For a program to be fault-tolerant, it needs to also handle the Errors that are Detected and Uncorrected (DUE), such as an ECC encountering too many bit flips in a codeword. While correcting an error has an overhead in itself, it can also affect the progress of a program. The most generic technique, rolling back the program state to a previously taken checkpoint, sets back any progress done since then. Alternately, application specific techniques exist, such as restarting an iterative program with its latest iteration's values as initial guess. We introduce a novel error correction technique for iterative linear solvers, designed to preserve both the progress made and the solver's future convergence by recovering the program's state exactly. Leveraging the asynchrony of task-based programming models, we mask our technique's overhead by overlapping error correction with the solver's normal workload. Our technique relies on analysing solvers to find redundancy in the form of relations between data. We are then able to restore discarded or corrupted data by recomputing or inverting the appropriate relations. We demonstrate that this approach allows to recover any part of three widely used Krylov subspace methods: CG, GMRES and BiCGStab, and their pre-conditioned versions. We implement our technique for CG and recover lost data at the scale of a memory page, which is the granularity at which Operating Systems (OS) report memory errors on commodity hardware, and study the effect of varying the memory page size to address non-standard sizes and the possible use of huge pages in High Performance Computing (HPC). When compared to checkpointing and to the state-of-the-art algorithmic restart technique, on small (8 cores) to large scale (1024 cores), our methods show less overhead. A trade-off arises between our straightforward and asynchronous approaches, based on the rate at which faults happen. At the lowest considered rate and page size, overlapping recoveries decreases their average cost from 5.40 to 2.24 percent of the ideal faultless execution time. Our methods generally outperform the state-of-the-art even with increased overheads on big page sizes, and perform similarly on edge cases. These results also indicate that our techniques are increasingly efficient as the matrix size increases. [ABSTRACT FROM AUTHOR]

In asynchronous crash-prone read/write shared-memory systems there is the notion of a snapshot object, which simulates the behavior of an array of single-writer/multi-reader (SWMR) shared registers that can be read atomically. Processes in the system can access the object invoking (any number of times) two operations, denoted $\mathsf {write}()$ and $\mathsf {snapshot}()$ . A process invokes $\mathsf {write}()$ to update the value of its register in the array. When it invokes $\mathsf {snapshot}()$ , the process obtains the values of all registers, as if it read them simultaneously. It is known that a snapshot object can be implemented on top of SWMR registers, tolerating any number of process failures. Snapshot objects provide a level of abstraction higher than individual SWMR registers, and they simplify the design of applications. Building a snapshot object on an asynchronous crash-prone message-passing system has similar benefits. The object can be implemented by using the known simulations of a SWMR shared memory on top of an asynchronous message-passing system (if less than half the processes can crash), and then build a snapshot object on top of the simulated SWMR memory. This paper presents an algorithm that implements a snapshot object directly on top of the message-passing system, without building an intermediate layer of a SWMR shared memory. To the authors knowledge, the proposed algorithm is the first providing such a direct construction. The algorithm is more efficient than the indirect solution, yet relatively simple. [ABSTRACT FROM AUTHOR]

The non-orthogonal multiple access (NOMA) allows allocating one carrier to more than one user at the same time in one cell. It is a promising technology to provide high throughput due to carrier reuse within a cell. In this paper, a novel interference cancellation (IC) technique is proposed for asynchronous NOMA systems. The proposed IC technique exploits a triangular pattern to perform the IC from all interfering users for the desired user. The bit error rate performance analysis of an uplink NOMA system with the proposed IC technique is presented, along with the comparison to conventional IC technique. The numerical and simulation results show that the NOMA with the proposed asynchronous IC technique outperforms the conventional IC. It is also shown that employing iterative IC provides significant performance gain for NOMA and the number of required iterations depends on the modulation level and the detection method. With hard-decision, two iterations are sufficient, however with soft-decision, two iterations are enough only for low modulation level, and more iterations are desirable for high modulation level. [ABSTRACT FROM AUTHOR]

Most graph algorithms are iterative in nature. They can be processed by distributed systems in memory in an efficient asynchronous manner. However, it is challenging to recover from failures in such systems. This is because traditional checkpoint fault-tolerant frameworks incur expensive barrier costs that usually offset the gains brought by asynchronous computations. Worse, surviving data are rolled back, leading to costly re-computations. This paper first proposes to leverage surviving data for failure recovery in an asynchronous system. Our framework guarantees the correctness of algorithms and avoids rolling back surviving data. Additionally, a novel asynchronous checkpointing solution is introduced to accelerate recovery at the price of nearly zero overheads. Some optimization strategies like message pruning, non-blocking recovery and load balancing are also designed to further boost the performance. We have conducted extensive experiments to show the effectiveness of our proposals using real-world graphs. [ABSTRACT FROM AUTHOR]

Remote Direct Memory Access (RDMA) is expected to be an integral communication mechanism for future exascale systems—enabling asynchronous data transfers, so that applications may fully utilize CPU resources while simultaneously sharing data amongst remote nodes. In this work we examine Network-induced Memory Contention (NiMC) on Infiniband networks. We expose the interactions between RDMA, main-memory and cache, when applications and out-of-band services compete for memory resources. We then explore NiMC’s resulting impact on application-level performance. For a range of hardware technologies and HPC workloads, we quantify NiMC and show that NiMC’s impact grows with scale resulting in up to 3X performance degradation at scales as small as 8K processes even in applications that previously have been shown to be performance resilient in the presence of noise. Additionally, this work examines the problem of predicting NiMC’s impact on applications by leveraging machine learning and easily accessible performance counters. This approach provides additional insights about the root cause of NiMC and facilitates dynamic selection of potential solutions. Lastly, we evaluated three potential techniques to reduce NiMC’s impact, namely hardware offloading, core reservation and software-based network throttling. [ABSTRACT FROM AUTHOR]

This paper presents operational modal analysis of an eight-storey concrete building using ambient vibration data collected in an ‘asynchronous’ manner, i.e., different sensors using possibly different clocks for data sampling. Five force-balance accelerometers were used with a number of setups to cover all locations of interests. Modal identification is performed using a Bayesian frequency domain method for asynchronous data and the global mode shape is assembled using the global least square method. The identified modal parameters based on asynchronous data are evaluated by comparing with those identified based on synchronous data. The identification uncertainties of modal parameters are investigated through the posterior coefficient of variation in a Bayesian context. The study provides insights into the challenges encountered when using asynchronous data for operational modal analysis in a practical context. [ABSTRACT FROM AUTHOR]

Perfectly-secure verifiable secret sharing (VSS) and multi-party computation (MPC) protocols in asynchronous network tolerate only at most one-fourth of corruption, while their counterparts in synchronous network sustain against at most one-third corruption. Moreover property-wise, synchronous protocols provide much stronger guarantees than the asynchronous counterparts. Taking note of the fact that asynchronous network is more realistic on one hand and on the other, synchrony of a network has positive impact on several aspects of distributed protocols including properties and fault-tolerance, we explore the power of hybrid networks that combines best of both the worlds by supporting a few synchronous rounds at the onset of a protocol execution, before turning to asynchronous mode. In hybrid networks, we investigate various feasibility questions pertaining to protocols giving guarantees attainable in synchronous and asynchronous networks. For the asynchronous protocols in hybrid networks, we hope to leverage the initial synchronous rounds to bridge the gap in the fault-tolerance with the synchronous protocols under minimal synchrony assumption. We ask the following fundamental question of both theoretical and practical importance: What is the minimum number of initial synchronous rounds necessary and sufficient in a hybrid network to construct asynchronous perfectly-secure VSS and MPC protocols with the fault-tolerance of synchronous protocols? On the positive note, we show that the answer is one for VSS which is clearly optimal. Notably no broadcast oracle is invoked in the synchronous round of our proposed VSS protocol. On the negative side, we prove that one synchronous round is not enough for MPC, putting MPC on a higher pedestal than VSS in terms of difficulty. For synchronous protocols in hybrid networks, we hope to save on the synchronous rounds leveraging conveniently the available asynchronous phase. We settle the question for VSS in the negative showing that three rounds that are known to be necessary (and sufficient) for VSS in synchronous networks, are also required in hybrid networks. VSS being a special case of MPC, the lower bound holds true for MPC. We match the lower bound with a three-round protocol. Notably, synchronous MPC with cryptographic security is known to be achievable in hybrid networks with one synchronous round. [ABSTRACT FROM AUTHOR]

In applications of distributed storage systems to distributed computing and implementation of key-value stores, the following property, usually referred to as consistency in distributed computing, is an important requirement: as the data stored changes, the latest version of the data must be accessible to a client that connects to the storage system. Motivated by technological trends where key-value stores are increasingly implemented in high-speed memory, an information theoretic formulation called multi-version coding is introduced in this paper in order to understand and minimize the memory overhead of consistent distributed storage. Multi-version coding is characterized by $\nu$ totally ordered versions of a message and a storage system with $n$ servers. At each server, values corresponding to an arbitrary subset of the $\nu$ versions are received and encoded. For any subset of $c$ servers in the storage system, the value corresponding to the latest common version or a later version, as per the total ordering, among the $c$ servers is required to be decodable. An achievable multi-version code construction via linear coding and a converse result that shows that the construction is asymptotically tight when $\nu |(c-1)$ are provided. An implication of the converse is that there is an inevitable price, in terms of storage cost, to ensure consistency in distributed storage systems. [ABSTRACT FROM AUTHOR]

Session types are behavioural types for guaranteeing that concurrent programs are free from basic communication errors. Recent work has shown that asynchronous session subtyping is undecidable. However, since session types have become popular in mainstream programming languages in which asynchronous communication is the norm rather than the exception, it is crucial to detect significant decidable subtyping relations. Previous work considered extremely restrictive fragments in which limitations were imposed to the size of communication buffer (at most 1) or to the possibility to express multiple choices (disallowing them completely in one of the compared types). In this work, for the first time, we show decidability of a fragment that does not impose any limitation on communication buffers and allows both the compared types to include multiple choices for either input or output, thus yielding a fragment which is more significant from an applicability viewpoint. In general, we study the boundary between decidability and undecidability by considering several fragments of subtyping. Notably, we show that subtyping remains undecidable even if restricted to not using output covariance and input contravariance. [ABSTRACT FROM AUTHOR]

The k-set agreement problem is a generalization of the consensus problem. Namely, assuming that each process proposes a value, every non-faulty process must decide one of the proposed values, under the constraint that at most k different values are decided. This is a hard problem in the sense that it cannot be solved in a pure read/write asynchronous system, in which k or more processes may crash. One way to sidestep this impossibility result consists in weakening the termination property, requiring only that a process decides if it executes alone during a long enough period of time. This is the well-known obstruction-freedom progress condition. Consider a system of nanonymous asynchronous processes that communicate through atomic read/write registers, and such that any number of them may crash. This paper addresses and solves the challenging open problem of designing an obstruction-free k-set agreement algorithm with only (n-k+1) atomic registers. From a shared memory cost point of view, our algorithm is the best algorithm known to date, thereby establishing a new upper bound on the number of registers needed to solve this problem. For the consensus case (k=1), the proposed algorithm is up to an additive factor of 1 close to the best known lower bound. Further, the paper extends this algorithm to obtain an x-obstruction-free solution to the k-set agreement problem that employs (n-k+x) atomic registers (with 1≤x≤k), as well as a space-optimal solution for the repeated version of k-set agreement. Using this last extension, we prove that n registers are enough for every colorless task that is obstruction-free solvable with identifiers and any number of registers. [ABSTRACT FROM AUTHOR]

The evolution of hardware architectures driven by the increasing requirement for performance and energy efficiency has led to complex HPC systems. In the context of Finite Element Methods, exposing massive parallelism on unstructured mesh computations with efficient load balancing and minimal synchronizations is challenging. Several parallelization strategies have to be combined together to exploit the multiple levels of parallelism. We propose several contributions aimed at addressing irregular codes and data structures in an efficient way. We have developed a hybrid parallelization approach based on the Divide & Conquer (D&C) principle which combines the distributed, shared, and vectorial forms of parallelism in a fine grain task-based parallelism approach applied to irregular structures. We experiment our approach using a matrix assembly step of an industrial application from Dassault Aviation on standard Xeon multicores and Xeon Phi KNC manycores. On 512 Intel Xeon E5-2670 Sandy Bridge cores, we surpass the pure MPI approach by up to 3 . 47 × and reach 77% of parallel efficiency using only 2000 vertices per core. On 4 Xeon Phi 5110p KNC, D&C has similar performance to 96 Intel Xeon E5-2670 Sandy Bridge cores; it achieves an excellent parallel efficiency of 96%, and up to 6 . 56 × speedup compared to pure MPI. [ABSTRACT FROM AUTHOR]

This paper considers a two-user asynchronous multicast scenario where both users request the same content at different time instances, and a base station simultaneously serves them with nonorthogonal transmission. To serve the asynchronous requests of the same content, we develop three nonorthogonal transmission schemes. The first scheme serves the asynchronous requests by unicast transmission and the second scheme enables multicast transmission for the asynchronous requests based on interference decoding capability at receiver. The third scheme combines the first and second schemes. For the three proposed schemes, we formulate completion time minimization problems that aim to minimize the time required to complete serving users, while ensuring a given quality constraint of streaming content. For each scheme, the feasibility condition in terms of transmit power and optimal rate control are investigated. In addition, we analytically compare the performance of the proposed schemes, and additionally, propose an opportunistic transmission that opportunistically switches three proposed schemes depending on the channel and power conditions. [ABSTRACT FROM PUBLISHER]

Filtered orthogonal frequency division multiplexing (F-OFDM) system is a promising waveform for 5G and beyond to enable the multi-service system and spectrum efficient network slicing. However, the performance for F-OFDM systems has not been systematically analyzed in the literature. In this paper, we first establish a mathematical model for an F-OFDM system and derive the conditions to achieve the interference-free one-tap channel equalization. In the practical cases (e.g., insufficient guard interval, asynchronous transmission, and so on), the analytical expressions for inter-symbol interference, inter-carrier interference, and adjacent-carrier interference are derived, where the last term is considered as one of the key factors for asynchronous transmissions. Based on the framework, an optimal power compensation matrix is derived to make all of the subcarriers having the same ergodic performance. Another key contribution of this paper is that we propose a multi-rate F-OFDM system to enable low-complexity low-cost communication scenarios, such as narrow-band Internet of Things, at the cost of generating inter-subband interference (ISubBI). Low computational complexity algorithms are proposed to cancel the ISubBI. The result shows that the derived analytical expressions match the simulation results, and the proposed ISubBI cancelation algorithms can significantly save the original F-OFDM complexity (up to 100 times) without significant performance loss. [ABSTRACT FROM PUBLISHER]

Multi-Protocol Label Switching for Traffic Engineering (MPLS-TE) technology is an intelligent and advanced tool for handling traffic through the core networks and implementing new services based on virtual transport. Since MPLS-TE combines channel and network layer mechanisms, network administrators can optimally integrate and allocate the traffic loads while maintaining the speed of technologies such as Asynchronous Transfer Mode (ATM) technology. In this paper, the problem of the developed algorithm of multi-path routing which allows us to determine the optimum number of independent shortest paths is theoretically solved. In details, the article proposes a way for finding the set of shortest paths using Dijkstra's algorithm, and then determination of the maximum flow for each of the shortest paths based on the mathematical concepts and finally, introducing the solution of the multi-criteria optimization problem for a set of shortest paths. According to our approach, optimizing the use of resources in the core networks is possible with using the MPLS-TE technology. [ABSTRACT FROM AUTHOR]

This paper presents concept and implementation of digital phase-location system, designed as a navigational aid for marine applications. The main feature of the proposed system is the ability to work in both synchronous mode, with one master station and set of slave stations synchronised with master, and in asynchronous mode with independent clocking of all stations. [ABSTRACT FROM AUTHOR]

Session types are used to describe communication protocols in distributed systems and, as usual in type theories, session subtyping characterizes substitutability of the communicating processes. We investigate the (un)decidability of subtyping for session types in asynchronously communicating systems. We first devise a core undecidable subtyping relation that is obtained by imposing limitations on the structure of types. Then, as a consequence of this initial undecidability result, we show that (differently from what stated or conjectured in the literature) the three notions of asynchronous subtyping defined so far for session types are all undecidable. Namely, we consider the asynchronous session subtyping by Mostrous and Yoshida for binary sessions, the relation by Chen et al. for binary sessions under the assumption that every message emitted is eventually consumed, and the one by Mostrous et al. for multiparty session types. Finally, by showing that two fragments of the core subtyping relation are decidable, we evince that further restrictions on the structure of types make our core subtyping relation decidable. [ABSTRACT FROM AUTHOR]

Multiple parallel queues are versatile hardware data structures that are extensively used in modern digital systems. To achieve maximum scalability, the multiple queues are built on top of a dynamically-allocated shared buffer that allocates the buffer space to the various active queues, based on a linked-list organization. This work focuses on dynamically-allocated multiple-queue shared buffers that allow their read and write ports to operate in different clock domains. The proposed dual-clock shared buffer follows a tightly-coupled organization that merges the tasks of signal synchronization across asynchronous clock domains and queueing (buffering), in a common hardware module. When compared to other state-of-the-art dual-clock multiple-queue designs, the new architecture is demonstrated to yield a substantially lower-cost implementation. Specifically, hardware area savings of up to 55 percent are achieved, while still supporting full-throughput operation. [ABSTRACT FROM AUTHOR]

MEMS sensor technology and advances in electronics, low-power processors and communication have enabled ubiquitous monitoring, providing significant opportunities for a wide range of applications including wearable devices for fitness and health tracking. However, due to the limited form factor required, there remains a challenging issue that limits even more the success of wearable devices: the limited lifetime due to the small energy storages that supply the devices. This limitation affects usability and forces the data processing to keep low-complexity to match the power constraints. As wireless communication is typically the most power hungry activity in wearable sensors devices, many techniques focus on reducing the communication power consumption. For this reason, advanced power management can be exploited to increase the lifetime of the devices. In this work, we present a wireless body area network with an adaptive power management strategy combining an ultra-low power wake up radio with context awareness. The context aware power manager is based on activity recognition, which is evaluated to decide which other nodes must be activated. The nano-power wake up receiver is used to reduce the idle listening power of the main radio and enable an asynchronous ultra-low power protocol. In order to evaluate the benefit, we present a real world application to assist elderly people in gait rehabilitation through a closed loop feedback. Experimental results demonstrate the benefit of the proposed power management in terms of energy efficiency. We evaluate the overall power consumption of the system and the lifetime extension, which can increase up to a factor of 4 depending on the amount of time the system can be placed in sleep mode. [ABSTRACT FROM AUTHOR]

The design and verification of distributed software systems is often hindered by their ever-increasing complexity and their asynchronous operational semantics. This article considers choreography specifications for distributed systems to reduce that complexity. We use labelled state-transitions systems as ground model for both choreographies and the corresponding distributed systems. Based on Event-B method, we propose a stepwise correct-by-construction model to build asynchronous distributed systems which a priori realise their choreographies. We rely on a sufficient and necessary realisability condition and we apply several refinement steps w.r.t. that condition to generate the distributed peers. The first refinement returns peer behaviours obtained by synchronous projection. The previously computed system is then refined into its asynchronous version using unbounded FIFO buffers. We prove, thanks to invariant preservation, that a sequence of exchanged messages is preserved at each refinement step. We provide a formalised proof of a realisability algorithm for deterministic choreographies. Besides that, our contribution is twofold: the approach is a priori and the problackposed solution scales up to any number of peers communicating with each other. [ABSTRACT FROM AUTHOR]

This article presents a new communication library developed to ease the implementation of both asynchronous and synchronous iterative methods. A mathematical and algorithmic framework about fixed-point methods is described to introduce this class of parallel iterative algorithms, although this library can be used for a larger class of parallel algorithms. After an overview of the main features, we describe detailed implementation aspects arising from the asynchronous context. While the library is mainly based on top of Message Passing Interface library, it has been designed to be easily extended to other types of communication middleware. Finally, some numerical experiments validate this new library, used for implementing both a classical parallel scheme and a sub-structuring approach of the Jacobi iterative method. [ABSTRACT FROM AUTHOR]

Multiple-contact cross-polarization (MC-CP) is applied to powder samples of ferrocene and l -alanine under magic-angle spinning (MAS) conditions. The method is described analytically through the density matrix formalism. The combination of a two-step memory function approach and the Anderson-Weiss approximation is found to be particularly useful to derive approximate analytical solutions for single-contact Hartmann-Hahn CP (HHCP) and MC-CP dynamics under MAS. We show that the MC-CP sequence requiring no pulse-shape optimization yields higher polarizations at short contact times than optimized adiabatic passage through the HH condition CP (APHH-CP) when the MAS frequency is comparable to the heteronuclear dipolar coupling, i.e ., when APHH-CP through a single sideband matching condition is impossible or difficult to perform. It is also shown that the MC-CP sideband HH conditions are generally much broader than for single-contact HHCP and that efficient polarization transfer at the centerband HH condition can be reintroduced by rotor-asynchronous multiple equilibrations-re-equilibrations with the proton spin bath. Boundary conditions for the successful use of the MC-CP experiment when relying on spin-lattice relaxation for repolarization are also examined. [ABSTRACT FROM AUTHOR]