Formal Specification of QoS Negotiation in ODP System

The future of Open Distributed Processing systems (ODP) will see an increasing of components number, these components are sharing resources. In general, these resources are offering some kind of services. Due to the huge number of components, it is very difficult to offer the optimum Quality of service (QoS). This encourages us to develop a model for QoS negotiation process to optimize the QoS in an ODP system. In such system, there is a High risk of software or hardware failure. To ensure good performance of a system based on our model, we develop it using a formal method. In our case, we will use Event-B to get in the end of our development a system correct by construction

Demand access communications for TDRSS users

The Tracking and Data Relay Satellite System (TDRSS) has long been used to provide reliable low and high-data rate relay services between user spacecraft in Earth orbit and the ground. To date, these TDRSS services have been implemented via prior scheduling based upon estimates of user needs and mission event timelines. While this approach may be necessary for large users that require greater amounts of TDRSS resources, TDRSS can potentially offer the planned community of smaller science missions (e.g., the small explorer missions), and other emerging users, the unique opportunity for services on demand. In particular, innovative application of the existing TDRSS Multiple Access (MA) subsystem, with its phased array antenna, could be used to implement true demand access services without modification to either the TDRSS satellites or the user transponder, thereby introducing operational and performance benefits to both the user community and the Space Network. In this paper, candidate implementations of demand access service via the TDRSS MA subsystem are examined in detail. Both forward and return link services are addressed and a combination of qualitative and quantitative assessments are provided. The paper also identifies further areas for investigation in this ongoing activity that is being conducted by GSFC/Code 531 under the NASA Code O Advanced Systems Program

Agrosystems and Ecosystem Services: an agroenvironmental assessment of vegetated systems for phytoremediation of water from agricultural drainage

Relationships between Ecosystem Services and agrosystems are extremely important both to understand the bidirectional flow of services from/to agriculture and to quantify goods and benefits for human societies. Wetland systems nowadays represent an important cornerstone for beneficial Ecosystem Services, especially in intensive agricultural landscapes characterized by shallow water and a dense minor channel network like the territory of the Venice Lagoon drainage system. Wetlands provide a crucial suite of regulating, supporting, provisioning and cultural services to regulate water flows and nutrient cycling, remove and detoxify excess fertilizers and pesticides, sequester carbon, enhance biodiversity and provide cultural benefits to local communities. By three experimental study cases this research present results about the assessment of the water purification service provided by wetlands in mitigating agricultural contamination; moreover, estimation of a provisioning service such as bioenergy derived from wetland vegetation was performed. In the study case “a constructed wetland for water purification services from pesticide in an intensive cropping system” results show that the system can reduce runoff concentration of metolachlor and terbuthylazine by a factor of 45-80 even in extreme flooding conditions. Herbicides retention in the constructed wetland was reversible, and the second and third floods mobilized 14-31% and 3.5-7.0% respectively, of the amount detected in the first flood. In the second experimentation “vegetated ditches as water purification systems to mitigate contamination from pesticides runoff” results show that the ditch can immediately reduce runoff concentration of herbicides by at least 50% even in extreme flooding conditions; as a general rule, a runoff of 1 mm from 5 ha is mitigated by 99% in 100 m of vegetated ditch. In the study case “Assessing phytoremediation performance of an integrated agricultural wetland” results show that median concentrations of total nitrogen were 2.43 ppm at the inlet and 1.79 at the outlet, while after an extreme rainfall event, total nitrogen concentrations were 6.34 ppm at the inlet and 1.29 ppm at the outlet. In general, wetland systems perform a high buffer capacity both for nutrient and herbicides, capable to provide water purification service, protecting downstream surface water. Moreover, this project confirms that the implementation of constructed wetlands and offsite mitigation measures like vegetated ditches in agro-systems can improve the sustainability of agricultural production

Computing infrastructure issues in distributed communications systems : a survey of operating system transport system architectures

The performance of distributed applications (such as file transfer, remote login, tele-conferencing, full-motion video, and scientific visualization) is influenced by several factors that interact in complex ways. In particular, application performance is significantly affected both by communication infrastructure factors and computing infrastructure factors. Several communication infrastructure factors include channel speed, bit-error rate, and congestion at intermediate switching nodes. Computing infrastructure factors include (among other things) both protocol processing activities (such as connection management, flow control, error detection, and retransmission) and general operating system factors (such as memory latency, CPU speed, interrupt and context switching overhead, process architecture, and message buffering). Due to a several orders of magnitude increase in network channel speed and an increase in application diversity, performance bottlenecks are shifting from the network factors to the transport system factors.This paper defines an abstraction called an "Operating System Transport System Architecture" (OSTSA) that is used to classify the major components and services in the computing infrastructure. End-to-end network protocols such as TCP, TP4, VMTP, XTP, and Delta-t typically run on general-purpose computers, where they utilize various operating system resources such as processors, virtual memory, and network controllers. The OSTSA provides services that integrate these resources to support distributed applications running on local and wide area networks.A taxonomy is presented to evaluate OSTSAs in terms of their support for protocol processing activities. We use this taxonomy to compare and contrast five general-purpose commercial and experimental operating systems including System V UNIX, BSD UNIX, the x-kernel, Choices, and Xinu

An event service supporting autonomic management of ubiquitous systems for e-health

An event system suitable for very simple devices corresponding to a body area network for monitoring patients is presented. Event systems can be used both for self-management of the components as well as indicating alarms relating to patient health state. Traditional event systems emphasise scalability and complex event dissemination for internet based systems, whereas we are considering ubiquitous systems with wireless communication and mobile nodes which may join or leave the system over time intervals of minutes. Issues such as persistent delivery are also important. We describe the design, prototype implementation, and performance characteristics of an event system architecture targeted at this application domain

Distributed Hybrid Simulation of the Internet of Things and Smart Territories

This paper deals with the use of hybrid simulation to build and compose heterogeneous simulation scenarios that can be proficiently exploited to model and represent the Internet of Things (IoT). Hybrid simulation is a methodology that combines multiple modalities of modeling/simulation. Complex scenarios are decomposed into simpler ones, each one being simulated through a specific simulation strategy. All these simulation building blocks are then synchronized and coordinated. This simulation methodology is an ideal one to represent IoT setups, which are usually very demanding, due to the heterogeneity of possible scenarios arising from the massive deployment of an enormous amount of sensors and devices. We present a use case concerned with the distributed simulation of smart territories, a novel view of decentralized geographical spaces that, thanks to the use of IoT, builds ICT services to manage resources in a way that is sustainable and not harmful to the environment. Three different simulation models are combined together, namely, an adaptive agent-based parallel and distributed simulator, an OMNeT++ based discrete event simulator and a script-language simulator based on MATLAB. Results from a performance analysis confirm the viability of using hybrid simulation to model complex IoT scenarios.Comment: arXiv admin note: substantial text overlap with arXiv:1605.0487

SymbioCity: Smart Cities for Smarter Networks

The "Smart City" (SC) concept revolves around the idea of embodying cutting-edge ICT solutions in the very fabric of future cities, in order to offer new and better services to citizens while lowering the city management costs, both in monetary, social, and environmental terms. In this framework, communication technologies are perceived as subservient to the SC services, providing the means to collect and process the data needed to make the services function. In this paper, we propose a new vision in which technology and SC services are designed to take advantage of each other in a symbiotic manner. According to this new paradigm, which we call "SymbioCity", SC services can indeed be exploited to improve the performance of the same communication systems that provide them with data. Suggestive examples of this symbiotic ecosystem are discussed in the paper. The dissertation is then substantiated in a proof-of-concept case study, where we show how the traffic monitoring service provided by the London Smart City initiative can be used to predict the density of users in a certain zone and optimize the cellular service in that area.Comment: 14 pages, submitted for publication to ETT Transactions on Emerging Telecommunications Technologie

The impact of business process outsourcing on firm performance and the influence of governance : a long term study in the German banking industry

Does BPO pay off at the firm-level? Although there are several studies which analyze the potential benefits of BPO, there is a virtual absence of research papers on BPO outcomes. Based on an analysis of 137 Business process outsourcing (BPO) ventures at 254 German banks in a period between 1994 and 2005, we found that the outsourcer's financial performance in terms of profitability and cost efficiency was increased significantly compared to industry peers without BPO. The increase stems not from workforce reductions but rather from increased employee productivity. Further, we show how BPO governance ensures BPO success: individually negotiated outsourcing contracts help to improve cost efficiency and profitability measures. Relational governance based on trust has only positive effects on profitability. Keywords: Business Process Outsourcing, firm performance, firm characteristics, banking, German banks, governance JEL Classifications: G21, L14, L21, L2