The rapid growth in demand for computational power driven by modern service applications combined with the shift to the Cloud computing model have led to the establishment of large-scale virtualized data centers. Such data centers consume enormous amounts of electrical energy resulting in high operating costs and carbon dioxide emissions. Dynamic consolidation of virtual machines (VMs) using live migration and switching idle nodes to the sleep mode allows Cloud providers to optimize resource usage and reduce energy consumption. However, the obligation of providing high quality of service to customers leads to the necessity in dealing with the energy-performance trade-off, as aggressive consolidation may lead to performance degradation. Because of the variability of workloads experienced by modern applications, the VM placement should be optimized continuously in an online manner. To understand the implications of the online nature of the problem, we conduct a competitive analysis and prove competitive ratios of optimal online deterministic algorithms for the single VM migration and dynamic VM consolidation problems. Furthermore, we propose novel adaptive heuristics for dynamic consolidation of VMs based on an analysis of historical data from the resource usage by VMs. The proposed algorithms significantly reduce energy consumption, while ensuring a high level of adherence to the service level agreement. We validate the high efficiency of the proposed algorithms by extensive simulations using real-world workload traces from more than a thousand PlanetLab VMs. Copyright © 2011 John Wiley & Sons, Ltd.

Optimal online deterministic algorithms and adaptive heuristics for energy and performance efficient dynamic consolidation of virtual machines in Cloud data centers

The present invention provides a heterocyclic compound and an organic light-emitting device including the heterocyclic compound. The organic light-emitting devices using the heterocyclic compounds have high-efficiency, low driving voltage, high luminance and long lifespan.

Organic light-emitting device

A compact and efficient optical system featuring planar multi-layered LED light source arrays concentrating their polarized or unpolarized output within a limited angular range. The optical system manipulates light emitted by a planar light emitters such as electrically-interconnected LED chips. Each light emitting region in the array is surrounded by reflecting side-walls whose output is processed by elevated prismatic films, polarization converting films, or both. The optical interaction between light emitters, reflecting sidewalls and the elevated prismatic films create overlapping virtual images between emitting regions that contribute to the greater optical uniformity. Practical illumination applications of such uniform light source arrays include compact LCD of DMD video image projectors, as well as general lighting, automotive lighting, and LCD backlighting.

Uniform illumination system

Elastic resource scaling lets cloud systems meet application service level objectives (SLOs) with minimum resource provisioning costs. In this paper, we present CloudScale, a system that automates fine-grained elastic resource scaling for multi-tenant cloud computing infrastructures. CloudScale employs online resource demand prediction and prediction error handling to achieve adaptive resource allocation without assuming any prior knowledge about the applications running inside the cloud. CloudScale can resolve scaling conflicts between applications using migration, and integrates dynamic CPU voltage/frequency scaling to achieve energy savings with minimal effect on application SLOs. We have implemented CloudScale on top of Xen and conducted extensive experiments using a set of CPU and memory intensive applications (RUBiS, Hadoop, IBM System S). The results show that CloudScale can achieve significantly higher SLO conformance than other alternatives with low resource and energy cost. CloudScale is non-intrusive and light-weight, and imposes negligible overhead (

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CloudScale: elastic resource scaling for multi-tenant cloud systems

Cloud systems require elastic resource allocation to minimize resource provisioning costs while meeting service level objectives (SLOs). In this paper, we present a novel PRedictive Elastic reSource Scaling (PRESS) scheme for cloud systems. PRESS unobtrusively extracts fine-grained dynamic patterns in application resource demands and adjust their resource allocations automatically. Our approach leverages light-weight signal processing and statistical learning algorithms to achieve online predictions of dynamic application resource requirements. We have implemented the PRESS system on Xen and tested it using RUBiS and an application load trace from Google. Our experiments show that we can achieve good resource prediction accuracy with less than 5% over-estimation error and near zero under-estimation error, and elastic resource scaling can both significantly reduce resource waste and SLO violations.

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PRESS: PRedictive Elastic ReSource Scaling for cloud systems

The principles of non-imaging optics, rather than imaging optics, are used to provide a high power LED illumination lamp that has a specified limited viewing angle. A compound parabolic flux extractor extracts and concentrates light emitted by an LED chip and a light pipe continues the concentration into the specified viewing angle. A lens or a diffusant may be used to modify the light output of the lamp. A light constructed as an array of the lamps is suitable for use as an automobile external light such as a center high mounted stop light.

Nonimaging light source

Recent advances in hardware and software virtualization offer unprecedented management capabilities for the mapping of virtual resources to physical resources. It is highly desirable to further create a "service hosting abstraction" that allows application owners to focus on service level objectives (SLOs) for their applications. This calls for a resource management solution that achieves the SLOs for many applications in response to changing data center conditions and hides the complexity from both application owners and data center operators. In this paper, we describe an automated capacity and workload management system that integrates multiple resource controllers at three different scopes and time scales. Simulation and experimental results confirm that such an integrated solution ensures efficient and effective use of data center resources while reducing service level violations for high priority applications.

1000 Islands: Integrated Capacity and Workload Management for the Next Generation Data Center

A variety of illumination devices are disclosed that are configured to manipulate light provided by one or more light-emitting elements (LEEs). In general, embodiments of the illumination devices feature one or more optical couplers that redirect illumination from the LEEs to a reflector which then directs the light into a range of angles. In some embodiments, the illumination device includes a second reflector that reflects at least some of the light from the first reflector. In certain embodiments, the illumination device includes a light guide that guides light from the collector to the first reflector. The components of the illumination device can be configured to provide illumination devices that can provide a variety of intensity distributions. Such illumination devices can be configured to provide light for particular lighting applications, including office lighting, task lighting, cabinet lighting, garage lighting, wall wash, stack lighting, and downlighting.

Illumination devices including multiple light emitting elements

A lamp has a reflective cup with a light emitting device in the bottom of the cup. A transparent material having an index of refraction n fills the cup and extends to a hemispherical surface with radius R and an equator parallel to the opening of the cup. The reflective walls of the cup project substantially all of the light within a cutoff cone having an included half angle equal to the Brewster's angle of the transparent material. The center of the hemispherical lens surface is spaced from the rim of the opening of the cup a distance R/n. Thus, the opening of the cup is the locus of aplanatic points of the equator if the hemisphere. Most rays from within the cup are incident on the hemispherical lens surface at no more than the complement of the Brewster's angle. Thus, minimal light losses occur at the interface between the transparent medium and air. An aplanatic image is formed outside the hemispherical lens of a virtual source comprising a hemispherical surface extending through the rim of the cup opening. Such optics may also be used for a light accepting device. These principles may also be applicable to a an elongated cavity with a semicylindrical lens of radius R and edges spaced from the edge of the cavity a distance R/n.

High efficiency lamp or light accepter

In one embodiment, a solid-state luminaire has a strip of high power LEDs, where each LED emits light into an optical coupler. Light from the optical coupler is then coupled into a light guide. Light coupled into the light guide is mixed and guided to an exit aperture of the light guide. An optical extractor proximate the exit aperture of the light guide redirects light outward, which is optionally redirected generally downward by a secondary reflector that extends outwardly along the length of the light guide. The secondary reflector may be configured to create a variety of light-emission patterns. The luminaire may be hung from a ceiling, in track lighting, used as a pendant or pedestal fixture, or in other applications.

Robert C. Gardner

Papers

Nonimaging light source

1000 Islands: Integrated Capacity and Workload Management for the Next Generation Data Center

Illumination devices including multiple light emitting elements

High efficiency lamp or light accepter

Solid-State Luminaire