네트워크 유량 알고리즘을 이용한 다중 드론 경로 계획

With an increasing number of processing elements (PEs) integrated on a single chip, fault-tolerant techniques are critical to ensure the reliability of such complex systems. In current reconfigurable architectures, redundant PEs are utilized for fault tolerance. In the presence of faulty PEs, the physical topologies of various chips may be different, so the concept of virtual topology from network embedding problem has been used to alleviate the burden for the operating systems. With limited hardware resources, how to reconfigure a system into the most effective virtual topology such that the maximum repair rate can be reached presents a significant challenge. In this article, a new approach using a maximum flow (MF) algorithm is proposed for an efficient topology reconfiguration in reconfigurable architectures. In this approach, topology reconfiguration is converted into a network flow problem by constructing a directed graph; the solution is then found by using the MF algorithm. This approach optimizes the use of spare PEs with minimal impacts on area, throughput, and delay, and thus it significantly improves the repair rate of faulty PEs. In addition, it achieves a polynomial reconfiguration time. Experimental results show that compared to previous methods, the MF approach increases the probability to repair faulty PEs by up to 50% using the same redundant resources. Compared to a fault-free system, the throughput only decreases by less than 2.5% and latency increases by less than 4%. To consider various types of PEs in a practical application, a cost factor is introduced into the MF algorithm. An enhanced approach using a minimum-cost MF algorithm is further shown to be efficient in the fault-tolerant reconfiguration of heterogeneous reconfigurable architectures.

Due to the ever-increasing density and complexity of integrated circuits, FPGA prototyping has become a necessary part of the design process. To enhance observability into these devices, designers commonly insert trace-buffers to record and expose the values on a small subset of internal signals during live operation to help root-cause errors. For dense designs, routing congestion will restrict the number of signals that can be connected to these trace-buffers. In this work, we apply optimal network flow graph algorithms, a well studied technique, to the problem of transporting circuit signals to embedded trace-buffers for observation. Specifically, we apply a minimum cost maximum flow algorithm to gain maximum signal observability with minimum total wirelength. We showcase our techniques on both theoretical FPGA architectures using VPR, and with a Xilinx Virtex6 device, finding that for the latter, over 99.6% of all spare RAM inputs can be reclaimed for tracing across four large benchmarks.

Visual appearance of moving or size-changing (either dilating (A) or contracting (B)) objects, which are shortly presented during the gaze fixation period (GFP), is usually connected with impossibility of clear seeing the start of the movement processes, while other stages of them basically is possible to observe. This is understandable assuming that perception of the movement location requires the possibility of organizing relations between signals coming at different moments of time, and realizing that initially these relations is not possible to obtain locally. It was shown (Artemenkov, VSS, 2005) that for high size-changing speed (around 40 deg/s and more) human visual perception (HVP) of A and B objects presented within a range of short durations (10–100 ms) is accompanied with unusual differences, e.g. appeared in effect of reversing seeing of initial and final locations of A and B contour objects: for A it is still impossible to perceive the initial stage and possible to see the final stage of the process, while for B there is quite opposite situation - the initial location is perceived and it is not possible to observe the end of the process. Studies of this phenomenon reveal that it may indicate the presence of an internal center-symmetric process anisotropy in the form creation process (FCP) having place during the GFP. If time needed for the initial FCP (or overall space integration) is increased with the size of the object and this process has a certain speed of formation then in case of high enough speed of objects' contraction their pictures coming later in time may reach the FCP image earlier than pictures, which came earlier. These causes presenting effect which may become a useful psychophysical tool for revealing internal mechanisms of the HVP and the determination of functional range of the form and movement perception.

Differential privacy is a method adopted to check for any privacy breach that occurs during communication for the exchange of confidential information. Here, in this work, differential privacy is being implemented in the context of vehicular ad hoc networks (VANETs). In this paper, we implement the concept of differential privacy using the Diffie–Hellman key exchange algorithm and the advanced encryption standards (AES) algorithms that are very powerful in terms of their performance. Algorithms like Laplace and Gaussian algorithms, which are currently the most commonly implemented algorithms, have been used for verification. The algorithms were analyzed by considering a situation where an initial location and final location have been defined and these have been encrypted using the mentioned algorithms and the privacy has been preserved.

<div class="section abstract"><div class="htmlview paragraph">Motivated by accurate representations in gear dynamics models, this work analyzes the force-deflection relationship between spur gear pairs when the gear teeth have tooth root cracks. A finite element/contact mechanics approach is used to accurately capture the elastic deformations of the gear mesh incorporating kinematic gear motion; elastic deflections of the teeth, root, and blank; and elastic contact between the mating gear teeth. Tooth root crack damage of fixed sizes are analyzed, and the resulting static transmission error and mesh stiffness are calculated. These FE/CM model outputs are relatively insensitive to important gear crack geometry, including the initial crack location, the path it follows, and its final location. Crack-induced changes in static transmission error and mesh stiffness are driven by the remaining amount of the tooth that is healthy. Calculations of average-slope and local-slope mesh stiffness are included because both are used in gear dynamic models.</div></div>

Predictive business process monitoring aims at providing the predictions about running instances by analyzing logs of completed cases of a business process. Recently, a lot of research focuses on increasing productivity and efficiency in a business process by forecasting potential problems during its executions. However, most of the studies lack suggesting concrete actions to improve the process. They leave it up to the subjective judgment of a user. In this paper, we propose a novel method to connect the results from predictive business process monitoring to actual business process improvements. More in detail, we optimize the resource allocation in a non-clairvoyant online environment, where we have limited information required for scheduling, by exploiting the predictions. The proposed method integrates offline prediction model construction that predicts the processing time and the next activity of an ongoing instance using LSTM with online resource allocation that is extended from the minimum cost and maximum flow algorithm. To validate the proposed method, we performed experiments using an artificial event log and a real-life event log from a global financial organization.

Context. The black hole candidate GX 339-4 exhibited an X-ray outburst in January 2010, which is still continuing. We here discuss the timing and the spectral properties of the outburst using RXTE data. Aims. Our goal is to study the timing and spectral properties of GX 339-4 using its recent outburst data and extract information about the nature of the accretion flow. Methods. We use RXTE archival data of the recent GX 339-4 outburst and analyze them with the NASA HEAsoft package, version 6.8. We then compare the observed quasi-periodic oscillation (QPO) frequencies with those from existing shock oscillation model and obtain the nature of evolution of the shock locations during the outburst. Results. We found that the QPO frequencies are monotonically increasing from 0.102 Hz to 5.69 Hz within a period of ~ 26 days. We explain this evolution with the propagating oscillatory shock (POS) solution and find the variation of the initial and final shock locations and strengths. The model fits also give the velocity of the propagating shock wave, which is responsible for the generation of QPOs and their evolutions, at ~ 10 m/s. We observe from the spectra that up to 2010 April 10, the object was in a hard state. After that, it went to the hard-intermediate state. On April 18, it had a state transition and went to the soft-intermediate state. On May 15, another state transition was observed and the source moved to the soft state. Conclusions. As in the previously fitted outburst sources, this source also showed the tendency of a rapidly increasing QPO frequency ($\nu_{QPO}$) in a viscous time scale, which can be modeled quite accurately. In this case, the shock seems to have disappeared at about ~ 172 Schwarzschild radii, unlike in the 2005 outburst of GRO J1655-40, where the shock disappeared behind the horizon.

A graphical representation of admissible profile times for robot trajectories is presented from a kinematic perspective. Profile times are defined to be the acceleration time, slew time, and deceleration time for robot end effector motions. Given initial and final robot end effector locations, identical profile times are computed for all the joints in the manipulator, where each joint has different acceleration and velocity limits. Ratio-locked profile times occur when the robot motion is joint-coordinated, with all of the joints moving in a proportional manner relative to each other. A closed-form solution to compute the minimum ratio-locked profile times for robot trajectories is presented for the case when the acceleration limit for each joint is equal to its deceleration limit. The algorithm is implemented in the HAL robot control system at HP Labs. for controlling robots in a manufacturing environment. >

To monitor damage developments in structures, various structural health monitoring methods based on different principles are used. The common aspect of elastic wave-based methods is to place appropriate sensors on the structure, to detect acoustic wave propagation and to analyze these signals the sensors transformed. The arrival time of these recorded signals to the sensors is the most significant parameter used to determine critical information such as the time and location of the damage. Therefore, the accurate calculation of the arrival time affects the accuracy of the damage detection. In this study, effects of the signal-to-noise ratio (SNR), sampling frequency, length of the signal, and length of the focal window on determining the arrival time of the signals to the sensors were investigated. For this purpose, an energy-traced arrival time picking approach (Akaike Information Criterion, AIC), which is the frequently used method in the literature, has been applied to a typical acoustic signal originated from a concrete cracking. The results of the study suggest the necessity of noise elimination, the optimum level of data logging and the ratios of focal window lengths for accurate time of arrival detection in the field monitoring of the structures using acoustic methods.

In this paper, we focus on the dynamic traffic assignment (DTA) problem on large-scale expressway networks especially under the condition of traffic events (such as severe weather, large traffic accidents etc.). We formulate the expressway network DTA problem as a nonconvex optimization problem. Considering the difficulty of solving the problem, we put forward an approximate solution algorithm based on the network flow theory with high computational efficiency and strong applicability. Specifically, a machine learning approach and a series of customization strategies of network flow model (including multi-origin and multidestination split, flow discretization and parallel edges addition methods) are proposed to transform the DTA problem into a resoluble network flow problem. After that, in order to improve the operational efficiency of an expressway network after traffic events occurring, the proposed network flow based two-layer DTA model (NTDM) is separated into two parts-traffic flow limitation model based on maximum flow algorithm and traffic assignment model based on minimum cost flow algorithm. Experiments on real expressway network data in some provinces of China show that our method can make a significant 26.03% reduction in saturation rate in a particular scenario. In efficiency test, the NTDM is at least 600 times faster than the traditional analytic method in a network with thousands of nodes.

In many regions of the world with complex seismic activity, the availability of seismic stations is limited. This motivated us to develop a probabilistic method for single‐station earthquake location. Single station location methods may provide an efficient and cost‐effective way to monitor small‐magnitude seismic events over large areas of the world. This method relies on the outputs of two neural networks, which predict the initial spatial location of specific areas (convolutional) used in the prior probability and seismic phase recognition (combination of convolutional and Long Short Term Memory) used in the likelihood function. These estimates and a 3D travel time likelihood function are used in a Bayesian framework. In this model, the initial spatial location is expressed as a Multivariate Gaussian Mixture Model, and the likelihood function refines the localization using the arrival time difference between S and P waves in a 3D space. The likelihood function uses a Fast Marching Eikonal method with a 3D velocity structure. We tested this method on the Ridgecrest 2019 seismic sequence (Mw = 7.1) and on West Texas and found promising results for locating with a single station. Our approach demonstrates that using a Bayesian model with strong priors obtained through deep learning algorithms is effective. Our model can predict epicenter and depth with mean errors of 7.55 km in longitude, 13.54 km in latitude and 0.630 km in depth at the two different locations studied. This method demonstrates the effectiveness of combining deep learning for initial estimations with probabilistic 3D location refinement.

Path planning field for autonomous mobile robot is an optimization problem that involves computing a collision-free path between initial location and goal location. In this paper, we present an improved artificial potential field based regression search (Improved APF-based RS) method which can obtain a global sub-optimal/optimal path efficiently without local minima and oscillations in complete known environment information. We redefine potential functions to eliminate non-reachable and local minima problems, and utilize virtual local target for robot to escape oscillations. Due to the planned path by improved APF is not the shortest/approximate shortest trajectory, we develop a regression search (RS) method to optimize the planned path. The optimization path is calculated by connecting the sequential points which produced by improved APF. Amount of simulations demonstrate that the improved APF method very easily escape from local minima and oscillatory movements. Moreover, the simulation results confirm that our proposed path planning approach could always calculate a more global optimal/near-optimal, collision-free and safety path to its destination compare with general APF. That proves our improved APF-based RS method very feasibility and efficiency to solve path planning which is a NP-hard problem for autonomous mobile robot.

Seismic bulletins, with trustworthy phase picks, origin times, and source locations are key for regional seismic studies, such as travel-time (TT) tomography, attenuation tomography, and anisotropy studies. To lay the groundwork for such studies in Israel, we revised the seismic bulletin of Israel and the surrounding area and obtained a trustworthy TT data set. From the earthquake and explosion bulletins of the Geophysical Institute of Israel, we compiled a starting data set of about 123,000 earthquakes and explosions that occurred during the past 40 yr. After screening out the poorly recorded events, we were left with a data set of ∼38,000 well-recorded events. We then revised the remaining data set in two consecutive steps. In the first, we reviewed and updated station metadata, including changes in station metadata parameters over time. In the second step, we jointly relocated a list of selected seismic events, using the Bayesian hierarchical location software package (BayesLoc) of Myers et al. (2007) that performs joint relocation of multiple events. We observed striking dissimilarities between the spatial distributions of the newly relocated catalog and the initial locations. Although the depth distribution of the starting catalog is trimodal with peaks at 0, 5, and 10 km, the distribution in this study is unimodal, with a broad peak between 7.5 and 12.5 km. By differencing the observed arrival times and the origin times obtained through relocation with BayesLoc, we obtained a revised TT database that consists of 261,336 Pg, 132,876 Pn, 114,816 Sg, and 60,394 Sn arrivals, from a set of 30,458 jointly relocated seismic sources. We compared prerevision and postrevision TTs as a function of epicentral distance and concluded that the revised data set contains far fewer outliers and inconsistencies than the original data set. The revised TT data set may be used for seismic studies, such as TT tomography, attenuation tomography, and anisotropy studies.

The single fibre pull-out test is an important micromechanical test used to evaluate the fibre-matrix interface of polymer matrix composites primarily under shear stress. Models interpreting force-displacement curves from pull-out tests often rely on assumptions about the stress distribution along the loaded fibre and crack behaviour at the fibre-matrix interface. This study aims to answer two critical questions: does the crack initiation and propagation at the interface proceed as in elastic materials, or is the debonding instantaneous as in ductile materials? And if elastic, where does the crack initiate and how does it propagate? To address these questions, an in situ optical investigation of the pull-out test under polarised light was conducted to observe crack initiation and propagation at the fibre-matrix interface under load. It was found that the location of crack initiation and the subsequent crack propagation were dependent on the ratio of the embedding length to the fibre diameter ( L / D ) for a given fibre-matrix combination. For short embeddings ( L / D < 4), cracks initiated at the embedded fibre's end and grew toward the fibre's entrance into the droplet. Unstable crack growth occurred if the remaining stress on the interface was not reduced with further crack extension. For long embeddings ( L / D > 4), cracks first appeared at the entrance of the fibre into the matrix. As the crack propagated and the remaining contact area between fibre and matrix decreased, the stress along the fibre resembled the short embedding situation, leading to a second crack arising at the fibre's end. Further loading resulted in both cracks growing toward each other until the rising stress in the remaining contact zone exceeded that needed for stable crack growth, and the fibre was completely detached. These findings enhance the understanding of fibre-matrix interactions and provide valuable insights for improving the interpretation of pull-out test results.

This paper deals with the computation of d-dimensional multicriteria shortest paths. In a weighted graph with arc weights represented by vectors, the cost of a path is the vector sum of the weights of its arcs. For a given pair consisting of a source s and a destination t, a path P dominates a path Q if and only if P 's cost is component-wise smaller than or equal to Q's cost. The set of Pareto paths, or Pareto set, from s to t is the set of paths that are not dominated. The computation time of the Pareto paths can be prohibitive whenever the set of Pareto paths is large. We propose in this article new algorithms to compute approximated Pareto paths in any dimension. For d = 2, we exhibit the first approximation algorithm, called Frame, whose output is guaranteed to be always a subset of the Pareto set. Finally, we provide a small experimental study in order to confirm the relevance of our Frame algorithm.