Virtual Links Research Articles

Bilinear enhancements of quandle invariants

We enhance the quandle counting invariants of oriented classical and virtual links using a construction similar to quandle modules but inspired by symplectic quandle operations rather than Alexander quandle operations. Given a finite quandle [Formula: see text] and a vector space [Formula: see text] over a field, sets of bilinear forms on [Formula: see text] indexed by pairs of elements of [Formula: see text] satisfying certain conditions yield new enhanced multiset- and polynomial-valued invariants of oriented classical and virtual links. We provide examples to illustrate the computation of the invariants and to show that the enhancement is proper.

A Multi-Objective Virtual Network Migration Algorithm Based on Reinforcement Learning

Virtual network migration (VNM) helps improve network performance by remapping a subset of virtual nodes or links to physical infrastructure, aligning the resource allocation to the virtual network&#x0027;s changing conditions. However, existing VNM methods neglect integrating multiple objectives that affect network performance, such as energy, communication, migration, and service level agreement violation (SLAV). It is challenging to make VNM decisions to optimize the overall objective in a large-scale cloud environment. This article establishes a multi-objective optimization model and proposes a multi-objective VNM algorithm called MiOvnm. The MiOvnm employs the double deep <inline-formula><tex-math notation="LaTeX"><?TeX $Q$?></tex-math></inline-formula>-learning approach to cope with ample state space. It also applies an action selection method called actfilter to deal with large-scale action space. The MiOvnm finds the migration action with optimal potential reward from the candidate action set. Simulation results demonstrate the superiority of our MiOvnm to the state-of-the-art methods. More specifically, MiOvnm reduces average SLAV, communication cost, and total cost by 24.32&#x0025;, 4.95&#x0025;, and 12.45&#x0025;, respectively. Furthermore, evaluation results in a real-world OpenStack platform reveal that making full use of computation and network resources, the MiOvnm reduces the completion time of computation- and network-intensive benchmarks by 11.35&#x0025; and 10.31&#x0025;, respectively, with a total cost reduction of 26.02&#x0025;.

The writhe and first intersection polynomials of virtual knots of supporting genus one

The supporting genus of a virtual knot is the minimal genus of all thickened surfaces where the virtual knot lies. In this paper, we study several polynomial invariants of a virtual knot of supporting genus one. We show that the first intersection polynomial of any virtual knot of supporting genus one is reciprocal. We also give a characterization of the writhe polynomial of a virtual knot of supporting genus one.

Trust-Aware Virtual Network Embedding in Wireless Sensor Networks

Network virtualization in wireless sensor networks (WSNs) enables the utilization of their shared sensing capabilities. Efficient assignment of WSN resources to maximize the infrastructure provider’s revenue can be achieved by virtual network embedding (VNE) while considering quality of information (QoI) (as the accuracy of sensing), quality of service (QoS) (as the reliability), and wireless interference handling constraints. Improving the acceptance ratio of VNE is essential because the more the virtual networks can be mapped onto the substrate network, the more revenue they will generate for the infrastructure provider. However, the shared and complex nature of VNE exposes the WSNs to security risks. This article develops a novel offline trust-aware virtual WSN (TA-VWSN) algorithm to maximize the virtual networks acceptance rate while minimizing the cost. This algorithm improves the QoI, QoS, and security by adding required trust level constraints to virtual nodes and links and trust level constraints to the substrate counterparts. Our algorithm embeds virtual nodes and links on substrate nodes and links with the required trust levels. The additional constraints increase the complexity of computation required to achieve an optimal solution. However, our TA-VWSN algorithm achieves a high-quality suboptimal solution in a short duration, enabling us to investigate the tradeoff between solution quality and search time. Our algorithm is also evaluated in large-scale network scenarios to verify all enforced limitations by the WSN substrate. While adding security constraints limits the acceptance ratio, the simulation results demonstrate its superiority in terms of average network throughput, measurement error efficiency, and processing time when the trust attributes are assigned, making the VNE algorithm more practical.

ReMatch: An Efficient Virtual Data Center Re-Matching Strategy Based on Matching Theory

A virtual data center (VDC) comprises multiple virtual machines (VMs) with communication dependencies represented as virtual links (VLs). These virtual components, i.e., VMs and VLs, often experience fluctuating demands across different resource types. In this article, we focus on addressing the issue of dynamic resource expansion that leads to the relocation of solution components (SCs), where a SC comprises a VM and its attached VLs, with either the VM and/or at least one of the VLs facing resource expansion. This is challenging because of the complexity involved in frequently relocating multiple dependent virtual components across the substrate network. This article presents a model called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ReMatch</i> that aims at building an efficient remapping plan with reduced remapping cost and improved resource utilization for service providers (SPs) in polynomial time. The overall relocation problem is formulated as a one-to-many matching game with heterogeneous VM demands. Owing to the inapplicability of the classical deferred acceptance algorithm (DAA) and revised DA (RDA), we propose a modified version of the RDA (MRDA) to obtain a weakly stable assignment. Thorough simulation and analysis show that <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ReMatch</i> outperforms the baseline algorithms considering multiple evaluation metrics.

Resource Abstractions in NFV Management and Orchestration: Experimental Evaluation

The expected complexity of shared 5G/6G cloud and network infrastructures requires a functional management and orchestration (MANO) architecture to automatically provision distinct vertical services. These are mapped as generic network services (NSes) specifying their computing and networking needs: Virtual Network Functions (VNFs) and Virtual Links. We focus on a hierarchical MANO implementation where a Resource Layer orchestrator handles the configuration of the physical infrastructure and exposes an abstract view of it to the upper-layer Service Orchestrator. Two different abstraction philosophies are adopted, namely the Infrastructure Abstraction, which pre-calculates the resource allocations before advertising them, and the Connection Service Abstraction, which exposes potential connectivity services without an actual resource allocation. The resulting abstracted infrastructure becomes the input of the Service Orchestrator to make (placement) decisions fulfilling the NS demands. Thus, a novel placement algorithm is devised which, unlike previous works, can handle NSes with arbitrary VNF topology demands. The performance of the MANO functions is experimentally evaluated by dynamically creating/terminating heterogeneous NSes in terms of: NS blocking, blocked bandwidth/VNF ratio, bandwidth occupancy, and VNF distribution per cloud site. From the results, Connection Service Abstraction does attain a more efficient use of resources and in general, performs better than the Infrastructure Abstraction approach.

NORD: NOde Ranking-based efficient virtual network embedding over single Domain substrate networks

Network virtualization (NV) allows the service providers (SPs) to partition the substrate resources in the form of isolated virtual networks (VNs) comprising multiple correlated virtual machines (VMs) and virtual links (VLs), capturing the dependencies. Though NV brought about multiple benefits, such as service isolation, improved quality-of-service (QoS), secure communication, and better utilization of substrate resources, it also introduced numerous research challenges. In this regard, one of the predominant challenges is assigning resources to the virtual components, i.e., VMs and VLs, also termed virtual network embedding (VNE). VNE comprises two closely related sub-problems, (i.) VM embedding and (ii.) VL embedding, and both the problems have been demonstrated to be NP-Hard. In the context of VNE, maximizing the revenue to cost ratio remains the focal point for the SPs as it not only boosts acceptance of VNRs but also effectively utilizes the substrate resources. However, the existing literature on VNE suffers from the following pitfalls: (i.) They only consider system resources or (ii.) limited topological attributes. However, both attributes are quintessential in accurately capturing the VNRs and the substrate network dependencies, thereby augmenting the revenue to cost ratio. This paper proposes an efficient VNE strategy called, NOde Ranking-based efficient virtual network embedding over single Domain substrate networks (NORD), to maximize the revenue to cost ratio. To address the problem of VM embedding, NORD utilizes a hybrid entropy and the technique for order of preference by similarity to ideal solution (TOPSIS) based ranking strategy for VMs and servers considering both system and topological attributes that effectively capture the dependencies. Once the ranking is generated, A greedy VM embedding followed by shortest path VL embedding completes the assignment. Simulation results confirm that NORD attains a 40% and 61% increment in average acceptance and revenue-to-cost ratios compared to the baselines.

Surveillance and Security Models Based on the Arduino UNO Interface

In the "digital era," where technology is advancing more quickly than anything else, security and surveillance systems are no exception (video surveillance cameras; fire alarms; security alarms; access systems; environmental measurement products detecting air pollution level, humidity, temperature etc.). This industry is constantly advancing in terms of technology. Artificial intelligence and many others are actively being introduced in this field. Of course, it is possible to buy the technological systems stated above. They are widely available online. However, their technological aspect and the principles behind creating such "smart" products are generally fascinating.&nbsp; https://innotech.ge/full-color-technology-2/ ;&nbsp;&nbsp; https://innotech.ge/. Today's most popular model&nbsp; Arduino UNO platform is used as an example to demonstrate how to build surveillance and security systems using its interface, which is based on the AIR Quality Semiconductor Sensor-MQ135 and the utilization of the PIR Motion Sensor block's characteristics. The project model integration process in both a virtual and physical context is described in detail and analyzed in the paper. The following are specifically used: An Arduino UNO microcontroller board, the Arduino Software IDE (Integrated Development Environment), a local code editor on the PC, and the virtual online platform tinkercad.com. The work is supplemented by pertinent electronic diagrams, schemes, software code, descriptions of fundamental functionalities, links to virtual project simulation, real-world application, and links to video recordings of the experiment in order to demonstrate the project model's smooth operation.

Index polynomial invariants of virtual knots using invariants for flat virtual knots

In this paper, we introduce new index polynomial invariants for virtual knots. They are defined by using invariants of flat virtual knots. And we give some properties of these invariants and examples.

Multi-Functional Time Expanded Graph: A Unified Graph Model for Communication, Storage, and Computation for Dynamic Networks Over Time

Space-air-ground integrated network (SAGIN) aided multi-tier computing network can be modelled as a dynamic and predictable network. For the SAGIN aided multi-tier computing network, the traditional time expanded graph (TEG) can only jointly model communication and storage capability, as well as one computing function for one mission flow within one same node. However, for multiple computing functions for one mission flow in one same node, TEG is not applicable. In this paper, for SAGIN aided multi-tier computing networks, we propose an multi-functional time expanded graph (MF-TEG) to jointly model the communication, storage, and computation capability of nodes where multiple computing functions for one mission flow in one same node can be characterized. Specifically, based on TEG, for each node having computation functions, we adopt the virtual network graph (VNG) to virtually decompose it into three virtual components: sub-virtual node, virtual computing nodes, and virtual transmission links, where the virtual computing node provides the computing function. We characterize the amount of data flow on each link and also present four kinds of fundamental constraints for the data flow in the MF-TEG for joint communication, storage, and computing function: computation capacity constraints, communication capacity constraints, storage capacity constraints, and flow conservation constraints. We provide one example of using MF-TEG to model the SAGIN aided multi-tier computing network with a service function chain (SFC), where satellite nodes could provide communication, storage, and multiple computing functions for one mission flow in one same node, where TEG is not valid. Furthermore, simulation results show that for SAGIN aided multi-tier computing network, the proposed MF-TEG model significantly outperforms the snapshot graph-aided VNG (SSG-aided VNG) model. The reason for that is only communication and computation capability is considered by the SSG-aided VNG model, while storage capability is not exploited.

Optimal network‐aware virtual data center embedding

SummaryRecently, the virtual data center embedding (VDCE) problem has drawn significant attention because of a growing need for efficient means of data center resource allocation. By ensuring a set of virtual data center (VDC) integration requests coming from his customers, among the main concern of an infrastructure provider is the maximization of the utilization rate of data center resources and benefits. However, existing VDCE solutions mostly focus on consolidating virtual machines in a single physical data center. Therefore, in this work, we improve the consolidated targets techniques, that consider only the virtual machines integration, by the consideration of network devices and fabrics (e.g., switches and paths/links). We consider new unreleased constraints such as multiple virtual nodes of the same request co‐location, and intermediate node requirements when a virtual link is mapped. To address the above problem, in this paper, we propose a binary linear programming‐based model, called BLP‐VDCE, to solve the VDCE problem with network‐aware consideration. This model ensures a simultaneous consolidated embedding of virtual nodes and virtual links. Extensive simulations show that solving the proposed BLP‐VDCE model can efficiently embed VDC requests with a high physical resource utilization rate.

The homological arrow polynomial for virtual links

The arrow polynomial is an invariant of framed oriented virtual links that generalizes the virtual Kauffman bracket. In this paper, we define the homological arrow polynomial, which generalizes the arrow polynomial to framed oriented virtual links with labeled components. The key observation is that, given a link in a thickened surface, the homology class of the link defines a functional on the surface’s skein module, and by applying it to the image of the link in the skein module this gives a virtual link invariant. We give a graphical calculus for the homological arrow polynomial by taking the usual diagrams for the Kauffman bracket and including labeled “whiskers” that record intersection numbers with each labeled component of the link. We use the homological arrow polynomial to study [Formula: see text]-nullhomologous virtual links and checkerboard colorability, giving a new way to complete Imabeppu’s characterization of checkerboard colorability of virtual links with up to four crossings. We also prove a version of the Kauffman–Murasugi–Thistlethwaite theorem that the breadth of an evaluation of the homological arrow polynomial for an “h-reduced” diagram [Formula: see text] is [Formula: see text].

Unknotting twisted knots with Gauss diagram forbidden moves

Twisted knot theory, introduced by Bourgoin, is a generalization of virtual knot theory. It is well known that any virtual knot can be deformed into a trivial knot by a finite sequence of generalized Reidemeister moves and two forbidden moves [Formula: see text] and [Formula: see text]. Similarly, we show that any twisted knot also can be deformed into a trivial knot or a trivial knot with a bar by a finite sequence of extended Reidemeister moves and three forbidden moves [Formula: see text], [Formula: see text] (or [Formula: see text]) and [Formula: see text] (or [Formula: see text]).

The intersection polynomials of a virtual knot I: Definitions and calculations

The intersection polynomials of a virtual knot I: Definitions and calculations

Wearable Antennas for Virtual Reality Cross-Body Links

Cross-body link refers to the wireless connection between two wearable devices when they are both worn or near the body, such as that of a virtual reality (VR) headset and its controllers. It is one of the most challenging wireless scenarios in terms of link budget, due to severe shadowing effects when controllers are placed at the back side of the body. This is especially true when the users are in an outdoor environment where there is less reflection from the surrounding. This paper investigates the wireless propagation mechanism, including line-of-sight, ground reflection, and creeping waves. Based on that, through simulation and measurement experiments, this work analyzes the impact of different antenna designs on the cross-body link of VR/AR devices, including one novel compact low-profile antenna named Distributed Monopole (DM), and two conventional antennas. Due to the polarization advantages, both the novel DM antenna and the patch antenna shows significantly better performance than the dipole antenna. The DM antenna also shows a 2-4 dB advantage over the patch antenna due to its omni-directional field pattern. Time-domain analysis and statistical approaches are suggested to fully characterize the cross-body link of VR/AR antennas and body propagation.

Trajectory tracking problem for a Flexible Mobile Manipulator: A Flatness Based Approach combined with Active Disturbance Rejection Control

This article proposes a suitable combination of Differential Flatness and Active Disturbance Rejection Control (ADRC) for the trajectory tracking problem on a flexible link mobile manipulator. The robot is composed of a flexible link (appendage) mounted on a cart and actuated at its base. A simplified virtual rigid link model, equipped with a rotational joint flexibility at the base, is proposed for modeling the nonlinear dynamics. The proposed model allows, quite realistically, to develop a robust controller on the closed loop behavior of the system. A finite element software (FEM software) is used to validate the proposed approach which simulates the dynamics of the real system. The robustness and effectiveness of the proposed control method is tested via realistic computer simulations with the FEM software, using physical parameters values obtained from an actual experimental platform. The obtained results are quite satisfactory in spite of un-modeled disturbances. Experiments, which are currently under way on an laboratory platform, will be reported elsewhere.

Optimal Renewable Energy Curtailment Minimization Control Using a Combined Electromobility and Grid Model

We propose an integrated power and transportation system control framework, combining the power grid model with a macroscopic electromobility model including charging stations under V2G operation. In this framework, the electrical vehicles (EVs) act as energy storage, but also as an additional virtual power grid link, transporting energy from one point to another. This new holistic model is used as a basis for optimal control design seeking to minimize renewable energy curtailment, while accounting for the structural limitation of the grid and other SoC constraints necessary for the optimal operation of the EVs. The proposed control scheme is shown to eliminate approximately 50% of curtailment compared to uncoordinated EV charging.

Classification of 2-component virtual links up to ${\varXi }$-moves

Classification of 2-component virtual links up to ${\varXi }$-moves

Augmented reality-based surgical guidance for wrist arthroscopy with bone-shift compensation

Background and objectivesIntraoperative joint condition is different from preoperative CT/MR due to the motion applied during surgery, inducing an inaccurate approach to surgical targets. This study aims to provide real-time augmented reality (AR)-based surgical guidance for wrist arthroscopy based on a bone-shift model through an in vivo computed tomography (CT) study. MethodsTo accurately visualize concealed wrist bones on the intra-articular arthroscopic image, we propose a surgical guidance system with a novel bone-shift compensation method using noninvasive fiducial markers. First, to measure the effect of traction during surgery, two noninvasive fiducial markers were attached before surgery. In addition, two virtual link models connecting the wrist bones were implemented. When wrist traction occurs during the operation, the movement of the fiducial marker is measured, and bone-shift compensation is applied to move the virtual links in the direction of the traction. The proposed bone-shift compensation method was verified with the in vivo CT data of 10 participants. Finally, to introduce AR, camera calibration for the arthroscope parameters was performed, and a patient-specific template was used for registration between the patient and the wrist bone model. As a result, a virtual bone model with three-dimensional information could be accurately projected on a two-dimensional arthroscopic image plane. ResultsThe proposed method was possible to estimate the position of wrist bone in the traction state with an accuracy of 1.4 mm margin. After bone-shift compensation was applied, the target point error was reduced by 33.6% in lunate, 63.3% in capitate, 55.0% in scaphoid, and 74.8% in trapezoid than those in preoperative wrist CT. In addition, a phantom experiment was introduced simulating the real surgical environment. AR display allowed to expand the field of view (FOV) of the arthroscope and helped in visualizing the anatomical structures around the bones. ConclusionsThis study demonstrated the successful handling of AR error caused by wrist traction using the proposed method. In addition, the method allowed accurate AR visualization of the concealed bones and expansion of the limited FOV of the arthroscope. The proposed bone-shift compensation can also be applied to other joints, such as the knees or shoulders, by representing their bone movements using corresponding virtual links. In addition, the movement of the joint skin during surgery can be measured using noninvasive fiducial markers in the same manner as that used for the wrist joint.

Design and implementation of P4 virtual switches and P4 virtual networks

This paper introduces the design and implementation of P4 virtual switches (VSWs) and P4 virtual networks (VNs). The proposed switch virtualization supports multiple VSWs embedded in a single P4 physical switch (PSW). Similar to a PSW, users use standard P4 language to program their VSWs. Given a set of VSWs and their target PSW, our hypervisor integrates all the VSW programs to generate configuration files that enable the target PSW to become a platform to realize switch virtualization. Users can define customized header types and metadata for their VSWs. In addition, our system supports live reconfiguration. Reconfiguring a VSW in a PSW will not interrupt the other VSWs in the PSW. Based on the proposed switch virtualization scheme, we present the way to share multiple VNs in a P4 physical network to provide multitenant services. A VN is composed of multiple VSWs and multiple virtual links (VL), and each VN is provisioned with guaranteed bandwidth for their VLs. Each tenant can control and manage its own VN—similar to a dedicated P4 network. In addition, each tenant can assign a priority to its traffic. The proposed network virtualization guarantees traffic isolation, preventing inter-VN interference. Results on an experimental network used for performance evaluation show that our system can successfully generate VSWs and VNs. The proposed hitless reconfiguration method can prevent service interruptions between VSWs during VSW reconfiguration. The experimental results also show that our network virtualization can accurately guarantee the provisioned bandwidths of VNs in a physical P4 network.