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About 10,000 papers for “virtual functions”
Ray Lischner · Apress eBooks · 2013
Deriving classes is fun, but there’s not a lot you can do with them—at least, not yet. The next step is to see how C++ implements type polymorphism, and this Exploration starts you on that journey.
Cited by 0
Uematsu, Tsuneo · arXiv (Cornell University) · 2002
We discuss the perturbatively calculable virtual photon structure functions. First we present the framework for analyzing the structure functions of the virtual photon and derive a first moment of $g_1^γ$ of the virtual photon. We then investigate the three positivity constraints satisfied by the eight structure functions of the virtual photon.
Cited by 0Open access
Jian-Wei Qiu, Xiaofei Zhang · Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields · 2001
We introduce operator definitions for virtual photon fragmentation functions, which are needed for reliable calculations of Drell-Yan transverse momentum ${(Q}_{T})$ distributions when ${Q}_{T}$ is much larger than the invariant mass Q. We derive the evolution equations for these fragmentation functions. We calculate the leading order evolution kernels for partons to fragment into an unpolarized as well as a polarized virtual photon. We find that fragmentation functions to a longitudinally polarized virtual photon are most important at small z, and the fragmentation functions to a transversely polarized virtual photon dominate the large z region. We discuss the implications of this finding to the $J/\ensuremath{\psi}$ mesons' polarization at large transverse momentum.
Cited by 19Open access
Roberto Riggio, Abbas Bradai, Davit Harutyunyan et al. · HAL (Le Centre pour la Communication Scientifique Directe) · 2016
International audience
Cited by 0Open access
Will Briggs · Apress eBooks · 2025
As a lazy programmer, I’m all about not rewriting code in all those subclasses I made. Consider the function draw for the various Shapes. Every time I draw, I should be sure I’m using the Shape’s color. I don’t want Circle::draw, Rectangle::draw, etc. to all have to do this separately – if nothing else, I’ll forget. So let’s adapt Shape so it can remember:
Cited by 0
Christian Makaya, Douglas Freimuth · 2016
Network functions virtualization (NFV) opens up a new ability of network enablement through agile network DevOps to design, develop, and test new services and to provide ongoing updates of existing services. This paper proposes a tool and methodology to aid the NFV designer to rapidly design and onboard new services and applications. Although the main focus is on the service design and onboarding, we provide the relation with other aspects such as management and orchestration, and service assurance of a complete lifecycle for network service. The proposed tool and methodology is called VNF Onboarding Automation Tool (VOAT). The prototype implementation is discussed as well as various use cases where VOAT has been used. With VOAT, an automated service design and onboarding can be efficiently achieved, hence reducing significantly the timeframe for deploying new services in telco cloud-based environment.
Cited by 7
Roberto Riggio, Abbas Bradai, Davit Harutyunyan et al. · IEEE Transactions on Network and Service Management · 2016
Network function virtualization (NFV) sits firmly on the networking evolutionary path. By migrating network functions from dedicated devices to general purpose computing platforms, NFV can help reduce the cost to deploy and operate large IT infrastructures. In particular, NFV is expected to play a pivotal role in mobile networks where significant cost reductions can be obtained by dynamically deploying and scaling virtual network functions (VNFs) in the core network. However, in order to achieve its full potential, NFV needs to extend its reach also to the radio access segment. Here, mobile virtual network operators shall be allowed to request radio access VNFs with custom resource allocation solutions. Such a requirement raises several challenges in terms of performance isolation and resource provisioning. In this work, we formalize the wireless VNF placement problem in the radio access network as an integer linear programming problem and we propose a VNF placement heuristic, named wireless network embedding (WiNE), to solve the problem. Moreover, we present a proof-of-concept implementation of an NFV management and orchestration framework for enterprise WLANs. The proposed architecture builds on a programmable network fabric where pure forwarding nodes are mixed with radio and packet processing capable nodes.
Cited by 130Open access
Bacelo, João Manuel Alves de Mesquita · Portuguese National Funding Agency for Science, Research and Technology (RCAAP Project by FCT) · 2021
Network Functions Virtualization (NFV) and Software Defined Networking (SDN) have been in the center of network evolution, promising a more flexible and efficient way of managing networks through the on-demand instantiation of network functions (NFs) and reconfigurability of the network as necessary. Nevertheless, as new mechanisms are developed, such technologies require testing before their adoption into real-world deployments. This is where this dissertation contributes, by proposing and evaluating a system architecture that integrates a physical wireless testbed with a cloud-based environment. This allows physical wireless nodes to become part of the cloud environment, enabling its use and configuration as virtual NFs (VNFs). Results showcased the system feasibility, with the testbed being able to instantiate on-demand virtual and physical NFs, in the physical wireless nodes and in an OpenStack data-center.
Cited by 0Open access
Christian Heinlein · OPUS (Aalen University) · 2005
Cited by 0
2009
In this article we will be discussing abstract classes, and how they are implemented in C++. The first part of the article will define abstract classes and describe how to use them as tools for Object Oriented Design. The second half of the article will concern itself with their implementation in C++, and some of the quirks and pitfalls that surround their use. While it is true that all objects are represented by a class, the converse is not true. All classes do not necessarily represent objects. It is possible, and often desirable, for a class to be insufficient to completely represent an object. Such classes are called abstract classes. The illustrations used in this article conform to the “Booch Notation ” for Object Oriented Design. This is a rich and expressive notation which is very useful for presenting OOD concepts. Where necessary I will digress to explain some of this notation. What is an Abstract Class? Simply stated, an abstract class is a class which does not fully represent an object. Instead, it represents a broad range of different classes of objects. However, this representation extends only to the features that those classes of objects have in common. Thus, an abstract class provides only a partial description of its objects. Because abstract classes do not fully represent an object, they cannot be instantiated. At first it may seem a little odd that a class is incapable of having any instances. But everyday life is full of such classes. We may describe a particular animal as belonging to the class of all Mammals. However, we will never see an instance of the class Mammal! At least not a pure instance. Every animal belonging to the class Mammal must also belong to a class which is subordinate to Mammal such as Mouse, Dog, Human, or Platypus. This is because the class Mammal does not fully represent any animal. In Object class, unless it is also an instance of a subordinate class. This is because the abstract class does not fully represent any object. As Booch says: “An abstract class is written with the expectation that its subclasses will add to its structure and behavior... ” 1
Cited by 0
Robert Walker · 2024
Cited by 0Open access
Palmer, Zachary Eli · Zenodo (CERN European Organization for Nuclear Research) · 2024
This archive contains a virtual machine image with a precompiled version of the artifact from the paper Intensional Functions, which appears in OOPSLA 2024 / PACMPL.
Cited by 1Open access
David M. Parks, E. M. Kamenetzky · International Journal for Numerical Methods in Engineering · 1979
Abstract The stiffness‐derivative method of Parks 1 for calculating the linear elastic crack tip stress intensity factor for any symmetric crack configuration and a particular loading is extended to calculate the weight function vector field 2,3 which serves as a Green's function for the stress intensity factor. The method, which combines the observations of Rice 3 on the weight function and of Zienkiewicz 4 on the differential stiffness method, permits very efficient determination of the weight function, requiring only one additional back‐substitution on the already‐factored stiffness matrix. Thus, the stress intensity factor for arbitrary loading of this configuration can subsequently be determined by quadrature alone. The promising extension of the method to three‐dimensional configurations is outlined. While this manuscript was under review, the authors became aware of the recent work of Vanderglas, 21 in which the same approach as ours is used to extend the stiffness derivative method. The present work was then voluntarily revised in order to address further certain aspects of the topic of shape function perturbation, which Vanderglas noted.
Cited by 65
Omar Houidi · theses.fr (ABES) · 2020
Cette these traite du placement optimal et heuristique de fonctions reseau et de chaines de fonction reseau dans des infrastructures cloud et reseau virtualisees. L'emergence de la virtualisation des fonctions reseau, connu sous l'acronyme NFV pour Network Function Virtualization, permet de decoupler les fonctions reseau en mode logiciel du materiel d'hebergement et de s'appuyer sur des serveurs generiques et d'eviter l'usage de, et la dependance a, des materiels dedies voire proprietaires.Le placement de fonctions reseau virtualisees (representees par VNF, Virtualized Network Functions) est NP-Difficile puisqu'il s'agit de projeter un petit graphe de ressources virtuelles sur un graphe plus grand (graphe de l'infrastructure d'hebergement). Les solutions optimales, en particulier la programmation lineaire en nombre entier (ILP), ne passent pas a l'echelle. Sachant que la demande est dynamique et peut varier dans le temps et que le reseau est lui meme variable dans le temps, il est important de prevoir des adaptations des placements. Cela peut s'effectuer par de l'elasticite sur les ressources d'hebergement reservees a une fonction reseau virtualisee, a un graphe de service reseau et par une extension du graphe de service lui meme en fonction du contexte et des exigences des utilisateurs ou tenants.La these propose une famille d'algorithmes pour le placement de chaines de services (ou fonctions) reseau avec la possibilite d'etendre les ressources d'hebergement des VNFs (c'est a dire assurer l'elasticite du service d'hebergement en augmentant les ressources allouees ou en generant plusieurs instances de VNFs pour ecouler le trafic et repondre a la demande) en plus du placement initial. Une solution en programmation en nombre entier est elaboree et aussi utilisee comme reference pour une comparaison avec l'etat de l'art et avec les extensions proposees. L'optimisation etant effectuee en instantanee au fur a mesure de l'arrivee des demandes, une a la fois, une solution qui regroupe plusieurs demandes pour y repondre simultanement, en elaborant un graphe composite, permet d'ameliorer les performances. Cette approche connue sous le nom de batch n'ameliore que partiellement la performance, la recompense sur le long terme (en efficacite, minimisation des ressources consommees, et en equilibrage de charge) est necessairement limitee.La these s'est penchee aussi sur l'extension de graphes de services reseau, de tenants, deja deployes, en adoptant une approche de type arbre de recouvrement, Spanning Tree. Plus specifiquement une modelisation du probleme en un Steiner Tree Problem a conduit a des performances proches de l'optimal pour des extensions de graphes au fil des demandes, en les traitant separement. Les travaux de these sont par la suite revenus sur la rentabilite sur le long terme des algorithmes, en approchant le placement de chaines de services et fonctions reseau comme un objectif long terme via de l'apprentissage par renforcement en se souciant plus de la rentabilite et de l'efficacite long terme des algorithmes contrairement aux approches visant exclusivement l'optimalite instantanee a chaque nouvelle demande.Cette these a permis de faire avancer autant que faire se peut l'etat de l'art du placement optimal dans les infrastructures cloud et reseau partagees. Notamment, le probleme, et besoin, d'extension de graphes, de tenants, deja deployes, sans perturber l'hebergement initial, a recu peu d'attention. Pourtant ce besoin est essentiel pour repondre a des deploiements additionnels de nouvelles fonctions et services reseau, et pour reagir aux degradations et a l'accroissement de la demande, aux attaques et pour assurer l'introduction de nouveaux services et fonctions de securite autour du graphe initial. L'approche peut aussi repondre a des modifications de graphes et d'isolations d'une partie (defectueuse ou compromise) d'un graphe et de son remplacement par d'autres services et graphes fiables et non alteres.
Cited by 5Open access
Langlet, Jonatan · KTH Publication Database DiVA (KTH Royal Institute of Technology) · 2020
Next generation mobile networks are designed to run in a virtualized environment, enabling rapid infrastructure deployment and high flexibility for coping with increasing traffic demands and new service requirements. Such network function virtualization imposes additional packet latencies and potential bottlenecks not present in legacy network equipment when run on dedicated hardware; such bottlenecks include PCIe transfer delays, virtualization overhead, and utilizing commodity server hardware which is not optimized for packet processing operations.Through recent developments in P4 programmable networking devices, it is possible to implement complex packet processing pipelines directly in the network data plane; allowing critical traffic flows to be offloaded and flexibly hardware accelerated on new programmable packet processing hardware, prior to entering the virtualized environment.In this thesis, we design and implement a novel hybrid NFV processing architecture which integrates programmable NICs and commodity server hardware, capable of offloading virtual network functions for specified traffic flows directly to the server network card; allowing these flows to completely bypass softwarization overhead, while less sensitive traffic process on the underlying host server.An evaluation in a testbed with customized traffic generators show that accelerated flows have significantly lower jitter and latency, compared with flows processed on commodity server hardware. Our evaluation gives important insights into the designs of such hardware accelerated virtual network deployments, showing that hybrid network architectures are a viable solution for enabling infrastructure scalability without sacrificing critical flow performance.
Cited by 0Open access
Markus H. J. Seifert · Drug Discovery Today · 2009
Cited by 78
周敬斐; 賴政良; 廖賀田 · 2011
Java是非常流行的物件導向程式語言，但它的類別檔中含有大量程式資訊，因而容易被逆編譯。本論文提出三種去除虛擬函數的方法，使混亂後的程式碼更不容易被研讀，也使關鍵技術能得到更好的保護.
Cited by 0
Meihui Gao, Bernardetta Addis, Mathieu Bouet et al. · arXiv (Cornell University) · 2017
-The emergence of Network Functions Virtualization (NFV) is bringing a set of novel algorithmic challenges in the operation of communication networks. NFV introduces volatility in the management of network functions, which can be dynamically orchestrated, i.e., placed, resized, etc. Virtual Network Functions (VNFs) can belong to VNF chains, where nodes in a chain can serve multiple demands coming from the network edges. In this paper, we formally define the VNF placement and routing (VNF-PR) problem, proposing a versatile linear programming formulation that is able to accommodate specific features and constraints of NFV infrastructures, and that is substantially different from existing virtual network embedding formulations in the state of the art. We also design a math-heuristic able to scale with multiple objectives and large instances. By extensive simulations, we draw conclusions on the trade-off achievable between classical traffic engineering (TE) and NFV infrastructure efficiency goals, evaluating both Internet access and Virtual Private Network (VPN) demands. We do also quantitatively compare the performance of our VNF-PR heuristic with the classical Virtual Network Embedding (VNE) approach proposed for NFV orchestration, showing the computational differences, and how our approach can provide a more stable and closer-to-optimum solution.
Cited by 0Open access
Silva, Miguel Ângelo Pereira da · Portuguese National Funding Agency for Science, Research and Technology (RCAAP Project by FCT) · 2019
In the current Vehicular Ad-hoc Networks (VANETs), the number of services and applications being used by the vehicles and its occupants is increasing. Nowadays, the majority of the services and applications are located outside the vehicular network which may imply an additional delay in services that are delay sensitive (e.g. road safety). In addition to that, these applications and services become inaccessible whenever the vehicular network loses contact with the infrastructure. This dissertation presents a practical solution that aims to minimize the impact of these problems. The solution focuses on using Network Function Virtualization (NFV) technologies to support the deployment of services at the edge of a mobility-enabled multihomed VANET, thus allowing certain services to be accessible in intermittent connectivity situations, as well as ensuring lower delays for critical services. These services are made up of lightweight Virtual Functions (VxFs) that are deployed at the edge of the VANET, as close as possible to the users. To evaluate the performance of the proposed solution several test scenarios, as well as use cases were developed. The results obtained show that the solution is capable of deploying services at the edge of the VANET with low delay and with recovery when in handover and mobility situations. The uses cases developed show that, for example, for a service which encompasses a single vehicle, if the vehicle loses connection with the infrastructure, both the operation and usage of the service are not affected. The use cases also show that, services deployed using the solution have lower delay values when compared with the same services when they are available in the cloud.
Cited by 0Open access
Palmer, Zachary Eli · Zenodo (CERN European Organization for Nuclear Research) · 2024
This archive contains a virtual machine image with a precompiled version of the artifact from the paper Intensional Functions, which appears in OOPSLA 2024 / PACMPL.
Cited by 0Open access