Optimal Migration Path Research Articles

NoSQL document data migration strategy in the context of schema evolution

In Agile development, one approach cannot be chosen and used all the time. Constant updates and strategy changes are necessary. We want to show that combining several migration strategies is better than choosing only one. Also, we emphasize the need to consider the type of schema change. This paper introduces a novel approach designed to optimize the migration process for NoSQL databases. The approach represents a significant advancement in migration strategy planning, providing a quantitative framework to guide decision-making. By incorporating critical factors such as schema changes, database size, the necessity of data in search functionalities, and potential latency issues, the approach comprehensively evaluates the migration feasibility and identifies the optimal migration path. Unlike existing methodologies, this approach adapts to the dynamic nature of NoSQL databases, offering a scalable and flexible approach to migration planning.

Multi-Controller Load Balancing Algorithm for Test Network Based on IACO

With the rapid increase of volume and complexity in the projectile flight test business, it is becoming increasingly important to improve the quality of the service and efficiency of multi-domain cooperative networks. The key for these improvements is to solve the problem of asymmetric load of multi-controllers in multi-domain networks. However, due to the current reality, it is difficult to meet the demands of future tests, and there is not guarantee of subnet multi-domain test load balancing. Most recent works have used a heuristic approach to seek the optimal dynamic migration path, but they may fall into the local optimum. This paper proposes an improved ant colony algorithm (IACO) that can transform the modeling of the mapping relationship between the switch and the controller into a traveling salesman problem by combining the ant colony algorithm and artificial fish swarm algorithm. The IACO not only ensures the load balancing of multi-controllers but also improves the reliability of the cluster. The simulation results show that compared to other algorithms such as traditional ant colony algorithms and distributed decision mechanisms, this IACO achieves better load balancing, improves the average throughput of multi-controller clusters, and effectively reduces the response time of controller request events.

Influence of complex interfacial rheology on the thermocapillary migration of a surfactant-laden droplet in Poiseuille flow

The effect of surface viscosity on the motion of a surfactant-laden droplet in the presence of a non-isothermal Poiseuille flow is studied, both analytically and numerically. The presence of bulk-insoluble surfactants along the droplet surface results in interfacial shear and dilatational viscosities. This, in turn, is responsible for the generation of surface-excess viscous stresses that obey the Boussinesq-Scriven constitutive law for constant values of surface shear and dilatational viscosities. The present study is primarily focused on finding out how this confluence can be used to modulate droplet dynamics in the presence of Marangoni stress induced by nonuniform distribution of surfactants and temperature along the droplet surface, by exploiting an intricate interplay of the respective forcing parameters influencing the interfacial stresses. Under the assumption of negligible fluid inertia and thermal convection, the steady-state migration velocity of a non-deformable spherical droplet, placed at the centerline of an imposed unbounded Poiseuille flow, is obtained for the limiting case when the surfactant transport along the interface is dominated by surface diffusion. Our analysis proves that the droplet migration velocity is unaffected by the shear viscosity whereas the dilatational viscosity has a significant effect on the same. The surface viscous effects always retard the migration of a surfactant-laden droplet when the temperature in the far-field increases in the direction of the imposed flow although the droplet always migrates towards the hotter region. On the contrary, if a large temperature gradient is applied in a direction opposite to that of the imposed flow, the direction of droplet migration gets reversed. However, for a sufficiently high value of dilatational surface viscosity, the direction of droplet migration reverses. For the limiting case in which the surfactant transport along the droplet surface is dominated by surface convection, on the other hand, surface viscosities do not have any effect on the motion of the droplet. These results are likely to have far-reaching consequences in designing an optimal migration path in droplet-based microfluidic technology.

Techno-economic analysis of NGNs implementation in rural areas based on the geographic and socio-demographic characteristics of Serbia

This paper presents a comprehensive techno-economic evaluation of the hybrid fiber-coax (HFC) networks and the multichannel Ethernet passive optical networks (EPONs) as two main next generation broadband technologies. The focus within this study is the comparison of these technologies in the case of their deployment in the rural area. Moreover, this paper analyzes how these technologies could be profitably deployed and what could be the optimal migration path for the operators in Europe.

Oxygen vacancy effects in HfO2-based resistive switching memory: First principle study

The work investigated the shape and orientation of oxygen vacancy clusters in HfO2-base resistive random access memory (ReRAM) by using the first-principle method based on the density functional theory. Firstly, the formation energy of different local Vo clusters was calculated in four established orientation systems. Then, the optimized orientation and charger conductor shape were identified by comparing the isosurface plots of partial charge density, formation energy, and the highest isosurface value of oxygen vacancy. The calculated results revealed that the [010] orientation was the optimal migration path of Vo, and the shape of system D4 was the best charge conductor in HfO2, which effectively influenced the SET voltage, formation voltage and the ON/OFF ratio of the device. Afterwards, the PDOS of Hf near Vo and total density of states of the system D4_010 were obtained, revealing the composition of charge conductor was oxygen vacancy instead of metal Hf. Furthermore, the migration barriers of the Vo hopping between neighboring unit cells were calculated along four different orientations. The motion was proved along [010] orientation. The optimal circulation path for Vo migration in the HfO2 super-cell was obtained.

A cost-effective scheme supporting adaptive service migration in cloud data center

Cloud computing as an emerging technology promises to provide reliable and available services on demand. However, offering services for mobile requirements without dynamic and adaptive migration may hurt the performance of deployed services. In this paper, we propose MAMOC, a cost-effective approach for selecting the server and migrating services to attain enhanced QoS more economically. The goal of MAMOC is to minimize the total operating cost while guaranteeing the constraints of resource demands, storage capacity, access latency and economies, including selling price and reputation grade. First, we devise an objective optimal model with multi-constraints, describing the relationship among operating cost and the above constraints. Second, a normalized method is adopted to calculate the operating cost for each candidate VM. Then we give a detailed presentation on the online algorithm MAMOC, which determines the optimal server. To evaluate the performance of our proposal, we conducted extensive simulations on three typical network topologies and a realistic data center network. Results show that MAMOC is scalable and robust with the larger scales of requests and VMs in cloud environment. Moreover, MAMOC decreases the competitive ratio by identifying the optimal migration paths, while ensuring the constraints of SLA as satisfying as possible.

A Genetic-Algorithm-Based Approach for Task Migration in Pervasive Clouds

Pervasive computing is converging with cloud computing which becomes pervasive cloud computing as an emerging computing paradigm. Users can run their applications or tasks in pervasive cloud environment in order to gain better execution efficiency and performance leveraging powerful computing and storage capacities of pervasive clouds through task migration. During task migration, there are possibly a number of conflicting objectives to be considered when making migration decisions, such as less energy consumption and quick response, in order to find an optimal migration path. In this paper, we propose a genetic algorithms- (GAs-) based approach which is effective in addressing multiobjective optimization problems. We have performed some preliminary evaluations of the proposed approach which shows quite promising results, using one of the classical genetic algorithms. The conclusion is that GAs can be used for decision making in task migrations in pervasive clouds.

Optimal migration path of Ag in HfO2: A first-principles study**Project supported by the National Natural Science Foundation of China (Grant No. 61376106).

First-principles calculations are used to investigate the migration path of Ag in the HfO2-based resistive random access memory (ReRAM). The formation energy calculation suggests that there are two different sites (site 1 and site 3) for the incorporation of Ag atoms into the HfO2 unit cell. Thermodynamic analysis shows that the motion of Ag atom in the HfO2 supercell appears to be anisotropic, which is due to the fact that the Ag atom at site 3 moves along the orientation, but the Ag atom at site 1 moves along the [001] orientation. The migration barriers of the Ag atoms hopping between neighboring unit cells are calculated along five different orientations. Difficulty in producing motion of the Ag atom varies with the migration barrier: this motion is minimized along orientation. Furthermore, The optimal circulation path for Ag migration within the HfO2 supercells is obtained, and is found to be approximately along the orientation. Therefore, it is proposed that the positive voltage should be applied along this orientation, the conduction filament may form more easily, which could improve the response time and reduce the power consumption in ReRAM applications.

Intravital imaging of Borrelia burgdorferi and murine innate immune cells during early cutaneous infection. (37.42)

Abstract After tick transmission, the spirochete, Borrelia burgdorferi (Bb), remains at the skin inoculation site for up to 48 hours before spreading and causing Lyme disease. Bb surface agonists should elicit potent inflammation and clearance in skin. However, the ID50 is <50 Bb, indicating efficient immunoevasion and suggesting that traditional in vitro models are inadequate for accurately characterizing Bb pathogenesis (i.e. most models display efficient Bb clearance by phagocytes). Thus, we have devised a confocal microscopy method for visualizing infectious fluorescent Bb in situ and in real-time. Here, we inject Bb into ear skin of anesthetized mice and collect four-dimensional data regarding Bb motility during natural infection. This data is complemented by quantitative PCR and histological analyses of the temporal fall and rise of spirochete numbers in vivo. By 4h, the majority of Bb at the injection site are immobile, while Bb adjacent to the site are highly motile. Two movement types are seen: 1) a back and forth shift that may aid Bb in finding an optimal migration path and 2) a directed run that navigates dermal structures. Analysis indicates an average Bb velocity of ≥100 um per minute in skin, which is >10x faster than any immune cell velocities observed in our model. This suggests that Bb motility is a primary mechanism for host cell evasion and indicates our imaging techniques will allow true delineation of host-Bb interactions critical for Lyme disease development.

Computer simulations of the effects of the Sitka eddy on the migration of sockeye salmon returning to British Columbia

The Sitka eddy is a mesoscale eddy, 300 km in diameter, that develops off SE Alaska in about one year in two. The eddy has surface currents exceeding 50 km day−1 and it has been suggested that the eddy could deflect migrating salmon to the south, thereby reducing the proportion of British Columbia (BC) sockeye salmon accessible to Alaskan fishers. We modelled its effects on the migration of sockeye salmon (Oncorhynchus nerka) returning to northern BC, using an individual‐based model to simulate migration paths, migration timing and metabolic costs of salmon with different migration behaviours. Except when their migration behaviour included positive rheotaxis, salmon that encountered the eddy had faster migration times and lower metabolic costs than those that did not. The least complex migration behaviour, compass orientation with no rheotaxis, was only slightly less efficient in metabolic terms than the optimal migration paths determined by dynamic programming. Our simulations show that the Sitka eddy itself does not deflect migrating salmon to the south or south‐east regardless of migration behaviour, but that by interrupting the normal northward flow of the Alaskan Current, the eddy could influence latitude of landfall of migrating salmon.

Self-diffusion along twist grain boundaries in Cu

In a previous paper we studied vacancy diffusion in two high-angle twist grain boundaries in Cu, using the EAM. In this paper, we discuss vacancy diffusion along four additional twist grain boundaries, from 8.8–43.6°. Vacancy formation energies in all the possible sites were calculated (0.14–1.42 eV) and found to be directly related to the degree of coincidence with the neighboring crystal planes. The optimal migration paths were found to coincide with the screw dislocations which comprise the boundary. Vacancy migration energies were found to be low (0.02–0.52 eV). The activation energies for self-diffusion at the boundaries were found to be less than half of the bulk value, in general agreement with experiment. Calculated diffusion rates, δD, for medium-high angle twist grain boundaries were in reasonable agreement with experimental data for polycrystalline material. Diffusion rates were found to decrease with increasing twist angle, in contrast with two sets of conflicting experimental data.

Structure and diffusion of clusters on Ni surfaces

The optimal structure of Ni clusters on Ni(100) and Ni(111) and Pt clusters on Ni(100) are studied using the embedded atom method (EAM). Unlike Ni and Pt clusters on Pt(100) [1,2], the clusters always preferred relatively closed-packed islands over linear chains. The structure of Ni clusters on Ni(111) were generally similar to those of Ir on Ir(111) [3]. Significant variations in dissociation energy indicate that certain “magic number” cluster sizes are favored over others. The diffusion mechanisms of the small clusters were investigated to determine the optimal migration paths and corresponding migration energies. The energy barriers for small clusters of Ni on Ni(100) are comparable to monomers, in qualitative agreement with recent FIM experiments for Pt x /Pt(100) [4]. For Ni x /Ni(111) migration energies generally increased with increasing cluster size, in qualitative agreement with experimental results for Ir clusters on Ir(111) [3].

Vacancy diffusion along twist grain boundaries in copper

Vacancy diffusion along two different high-angle twist grain boundaries (Σ5 and Σ13) was studied using the Embedded Atom Method (EAM). Vacancy formation energies in all the possible sites were calculated and found to be directly related to the degree of coincidence with the neighboring crystal planes. Optimal migration paths and migration energies were determined and found to be very low. The activation energies for self-diffusion at the boundaries were found to be less than half of the bulk value.