Fog Systems Research Articles

SNA Based Resource Optimization in Optical Network using Fog and Cloud Computing

Optical transmission has emerged as the most cost-effective technology to implement high-bandwidth based communications and to transmit the huge volume of data with low latency. Fog computing extends cloud computing to improve efficiency and reduces the amount of data to be transferred to the cloud for data processing, analysis, and storage etc. In this paper, a new fog layer among optical elements is proposed that utilizes the resources of the optical network. It uses passive optical network (PON), optical line terminals (OLTs) and optical network units (ONUs) to deliver cloud-based services more effectively with minimum latency. A large number of jobs and limited resources in fog layer lead to the deadlock that affects the Quality of Service (QoS) and reliability in heterogeneous fog and cloud environment. Therefore, Social Network Analysis (SNA) based deadlock manager is proposed with a new concept of Free Resource Fog (FRF) that helps to remove deadlock by collecting available free resources from all running jobs. In order to utilize resources and minimize the response time of the submitted job, a rule-based algorithm is proposed that assigns priorities to the jobs and provides resources accordingly from fog and cloud. In addition, energy consumption and latency measure are presented those reflects the QoS as well as reliability to end users. Gephi is used for the implementation of SNA based deadlock management whereas Cloudsim is used to evaluate the utilization of fog and cloud computing resources using Resource Pool Manager (RPM). Finally, we conclude that optimum resource utilization and latency measures can enable future computing with optical fog systems.

Modeling and Security in Cloud Ecosystems

Clouds do not work in isolation but interact with other clouds and with a variety of systems either developed by the same provider or by external entities with the purpose to interact with them; forming then an ecosystem. A software ecosystem is a collection of software systems that have been developed to coexist and evolve together. The stakeholders of such a system need a variety of models to give them a perspective of the possibilities of the system, to evaluate specific quality attributes, and to extend the system. A powerful representation when building or using software ecosystems is the use of architectural models, which describe the structural aspects of such a system. These models have value for security and compliance, are useful to build new systems, can be used to define service contracts, find where quality factors can be monitored, and to plan further expansion. We have described a cloud ecosystem in the form of a pattern diagram where its components are patterns and reference architectures. A pattern is an encapsulated solution to a recurrent problem. We have recently expanded these models to cover fog systems and containers. Fog Computing is a highly-virtualized platform that provides compute, storage, and networking services between end devices and Cloud Computing Data Centers; a Software Container provides an execution environment for applications sharing a host operating system, binaries, and libraries with other containers. We intend to use this architecture to answer a variety of questions about the security of this system as well as a reference to design interacting combinations of heterogeneous components. We defined a metamodel to relate security concepts which is being expanded.

Out of the fog: Catalyzing integrative capacity in interdisciplinary research

Social studies of interdisciplinary science investigate how scientific collaborations approach complex challenges that require multiple disciplinary perspectives. In order for collaborators to meet these complex challenges, interdisciplinary collaborations must develop and maintain integrative capacity, understood as the ability to anticipate and weigh tradeoffs in the employment of different disciplinary approaches. Here we provide an account of how one group of interdisciplinary fog scientists intentionally catalyzed integrative capacity. Through conversation, collaborators negotiated their commitments regarding the ontology of fog systems and the methodologies appropriate to studying fog systems, thereby enhancing capabilities which we take to constitute integrative capacity. On the ontological front, collaborators negotiated their commitments by setting boundaries to and within the system, layering different subsystems, focusing on key intersections of these subsystems, and agreeing on goals that would direct further investigation. On the methodological front, collaborators sequenced various methods, anchored methods at different scales, validated one method with another, standardized the outputs of related methods, and coordinated methods to fit a common model. By observing the process and form of collaborator conversations, this case study demonstrates that social studies of science can bring into critical focus how interdisciplinary collaborators work toward an integrated conceptualization of study systems.

Synthesis of State-of-the-Art in Visibility Detection Systems’ Applications and Research

Visibility is a critical component to the task of driving on all types of roads. The visibility detection and warning systems provide real-time, automated detection as well as appropriate responses to counteract reduced visibility conditions due to fog, heavy rain, snow, smoke, dust, or haze by informing drivers of present conditions and lowering the speed limits to match the reduced visibility condition. The objective of this research is to provide a synthesis of visibility detection systems and traffic control techniques that are developed and/or implemented in the United States and around the world. This article provides an overview of the best practices of fixed visibility systems at areas of recurrent dense fog and mobile systems for seasonal visibility reduction for areas of predicted seasonal fog or smoke from wildfires. Ongoing research efforts of developing new camera-based visibility detection systems are also discussed.

Sonic anemometry to evaluate airflow characteristics and temperature distribution in empty Mediterranean greenhouses equipped with pad–fan and fog systems

Sonic anemometry has been used to analyse two greenhouse evaporative cooling systems: a pad–fan system and a low pressure water/air fog system. These systems were used in empty greenhouses to simulate the microclimatic conditions produced inside Mediterranean greenhouses when crops are seeded in nurseries or transplanted in commercial greenhouses. Evaporative cooling systems could be necessary in the future for all Mediterranean greenhouses to reduce excess heat and to maintain certain levels of relative humidity on hot days from spring to autumn. The pad–fan system proved capable of maintaining more favourable conditions than the fog system. The best results were obtained by combining the evaporative pads with shading screens (differences of 1.4–1.8 °C between inside and outside temperature). The main drawbacks of the pad–fan system were the horizontal and vertical temperature gradients, with a maximum temperature difference between pads and fans of up to 11.4 °C, and a maximum difference of 6.7 °C between heights of 2 m and 1 m. However, inside temperature and relative humidity were more stable over time in the greenhouse using the pad–fan system. The fog system required higher energy consumption (7.2–8.9 kWh) than the pad–fan system (5.1 kWh) for continuous operations over 1 h. Nevertheless, the average water consumption of the pads (122.3 l h−1) is greater than that of the fog system (9.4 l h−1).

Technical and Economical Evaluation of Media and Fog Systems in Fars, Qom, Yazd, Shahid Rajaee Power Plants

In the hot days of summer, the efficiency of gas turbine is extremely reduced because the input air to compressors becomes hot. For solving this problem, one can increase the efficiency of the power house by charging to decrease the input air temperature to the compressor of gas turbine. In this paper, all kinds of cooling the inlet air to the gas turbine are introduced and then the technical and economical evaluation of these installed cooling system in Shahid Rajaee, Qom, Fars and Yazd power plants are expressed and the results show that the fog system cannot prove its effectiveness in Shahid Rajaee and Qom power plants. Whereas the installation of media systems in Fars combined cycle power plant produces more megawatt than its guarantee conditions and no particular problem has been observed.

Water-based Cold Protection of Chill-sensitive Foliage Plants in Shadehouses

Four water-based cold protection systems [under-benches mist (UBM), over-roadways mist (ORM), and two among-plants fog (APF1, APF2)] were evaluated for their water use and effectiveness in protecting ornamental foliage plants from chilling injury (CI) under protected shade structures at three commercial locations in Florida. UBM used a two-stage thermostat-controlled system with mist nozzles on 25-cm above-ground risers combined with an overhead retractable heat curtain. Both ORM and APF1 had seasonally applied polyethylene film cladding and manually controlled irrigation systems. The ORM system had the mist nozzles located 1.8 m high and APF1 and APF2 systems had the low-pressure fog nozzles mounted on 25-cm above-ground risers spaced among the plants. Temperature data loggers were placed outside and inside the northwest sections of the shadehouses. ORM and the two APF systems were evaluated during freeze events in 2006, 2007, and 2008 and UBM only in 2007 and 2008. UBM, ORM, and APF1 successfully kept the shadehouse temperatures above critical chilling temperatures for all of the foliage plants. APF2 protected all foliage crops except for jungle drum “palm” (Carludovica sp.) that sustained CI. At the UBM site, the air temperatures recorded inside the shadehouse were ≈17 °C warmer than outside. Both ORM and APF1 maintained adequately warm temperatures inside the shadehouses; however, the fog system maintained equal or higher temperatures than the mist system and used 86% less water. Inside temperatures were lower with APF2 than APF1 although the emitter type was the same and the water application rates were similar. These temperature differences were attributable to the greater APF2 shadehouse surface area (SA) and volume (V) compared with APF1 and indicate that the SA and V of structures being heated need to be considered when designing water-based low-pressure fog heating systems. The ORM and both fog systems conserved water compared with using the conventional sprinkler irrigation systems. These results show the potential of water-based approaches for maintaining shadehouses above chilling temperatures during freeze events.

Response of an eggplant crop grown under Mediterranean summer conditions to greenhouse fog cooling

The effects of greenhouse cooling using a high-pressure fog system on greenhouse microclimate and on eggplant ( Solanum melongena) crop response were studied at the coastal area of western Greece. Measurements were carried out in two distinct greenhouse compartments involving: (1) no air humidity control and (2) a fog system operating in order to obtain a greenhouse air relative humidity of 80%. Fog cooling reduced mean fruit temperature by about 3 °C and maintained greenhouse air temperature below 32 °C, while maximum temperature without cooling reached 40 °C. Furthermore, fogging reduced air vapor pressure deficit by about 55% and increased crop stomatal conductance by about 73%. These changes, in combination with alterations in crop aerodynamic conductance, resulted in around 31% decrease of crop transpiration rate. Fog system cooling efficiency was relatively low (46%) resulting in relatively high water consumption for fog cooling, reaching an equivalent to about 60% of crop water uptake. Nevertheless, since fog cooling decreased crop water needs, total greenhouse water consumption with fog cooling was only 19% higher than with no air humidity control. These results indicate the need to increase the cooling efficiency of fog systems in order to reduce greenhouse water consumption. Furthermore, the fog system enhanced mean fruit weight and marketable fruits, but appreciably reduced total fruit number per plant. Finally, fog cooling did not affect fruit quality characteristics such as fruit resistance to penetration, skin colour, fruit titratable acidity and total soluble solids.

MICROCLIMATE CONTROL IN GREENHOUSES BASED ON PHYTOMONITORING DATA AND MOLLIER PHASE DIAGRAM

MICROCLIMATE CONTROL IN GREENHOUSES BASED ON PHYTOMONITORING DATA AND MOLLIER PHASE DIAGRAM