Storage Engine Research Articles

Rose

Rose is a database storage engine for high-throughput replication. It targets seek-limited, write-intensive transaction processing workloads that perform near real-time decision support and analytical processing queries. Rose uses log structured merge (LSM) trees to create full database replicas using purely sequential I/O, allowing it to provide orders of magnitude more write throughput than B-tree based replicas. Also, LSM-trees cannot become fragmented and provide fast, predictable index scans. Rose's write performance relies on replicas' ability to perform writes without looking up old values. LSM-tree lookups have performance comparable to B-tree lookups. If Rose read each value that it updated then its write throughput would also be comparable to a B-tree. Although we target replication, Rose provides high write throughput to any application that updates tuples without reading existing data, such as append-only, streaming and versioning databases. We introduce a page compression format that takes advantage of LSM-tree's sequential, sorted data layout. It increases replication throughput by reducing sequential I/O, and enables efficient tree lookups by supporting small page sizes and doubling as an index of the values it stores. Any scheme that can compress data in a single pass and provide random access to compressed values could be used by Rose. Replication environments have multiple readers but only one writer. This allows Rose to provide atomicity, consistency and isolation to concurrent transactions without resorting to rollback, blocking index requests or interfering with maintenance tasks. Rose avoids random I/O during replication and scans, leaving more I/O capacity for queries than existing systems, and providing scalable, real-time replication of seek-bound workloads. Analytical models and experiments show that Rose provides orders of magnitude greater replication bandwidth over larger databases than conventional techniques.

The technoeconomic assessment of the hydrogen fuel chain

Options for hydrogen fuel chain are compared with the existing petroleum-based fuel chain for transportation. The criteria used are the life cycle cost (Rs/km), Greenhouse Gas (GHG) emissions (g/km) and Nonrenewable Energy (NRE) consumption (MJ/km). Four hydrogen production methods, one hydrogen transport method, three hydrogen storage methods and two on-board energy conversion methods are analysed. Each fuel chain option is analysed in MATLAB to calculate the force and power requirement of vehicles for the Indian urban drive cycle. It is found that most of the hydrogen fuel chains are sustainable based on GHG emission and NRE use. However, the cost is significantly higher (for photovoltaics, electrolysers and fuel-cell based systems) than the existing petroleum-based fuel chain. Hydrogen fuel chains based on a Steam Methane Reforming (with an IC engine) are economically viable but have higher GHG emissions. When biomass is freely available, hydrogen based on biomass gasification (with compressed hydrogen storage and IC engine) performs better than the existing petrol-based fuel chain on all criteria. However, when biomass is grown commercially, this fuel chain is unviable. This analysis reveals the merits and demerits of hydrogen fuel chains over the existing petroleum-based fuel chains and can set cost and performance targets for hydrogen technology options.

Storing and Searching Metadata for Digital Broadcasting on Set-Top Box Environments

Digital broadcasting is a novel paradigm for the next generation broadcasting. Its goal is to provide not only better quality of pictures but also a variety of services that is impossible in traditional airwaves broadcasting. One of the important factors for this new broadcasting environment is the interoperability among broadcasting applications since the environment is distributed. Therefore the broadcasting metadata becomes increasingly important and one of the metadata standards for a digital broadcasting is TV-Anytime metadata. TV-Anytime metadata is defined using XML schema, so its instances are XML data. In order to fulfill interoperability, a standard query language is also required and XQuery is a natural choice. There are some researches for dealing with broadcasting metadata. In our previous study, we have proposed the method for efficiently managing the broadcasting metadata in a service provider. However, the environment of a Set-Top Box for digital broadcasting is limited such as low-cost and low-setting. Therefore there are some considerations to apply general approaches for managing the metadata into the Set-Top Box. This paper proposes a method for efficiently managing the broadcasting metadata based on the Set-Top Box and a prototype of metadata management system for evaluating our method. Our system consists of a storage engine to store the metadata and an XQuery engine to search the stored metadata and uses special index for storing and searching. Our two engines are designed independently with hardware platform therefore these engines can be used in any low-cost applications to manage broadcasting metadata.

Microbial growth in aviation fuel

Growth of microorganisms in petroleum products has been recorded since 1895, causing fouling, malfunction and corrosion in storage tanks, airfield equipment, pipelines, airframes and engines. This paper considers the problems that fuel microbes pose to the aviation industry and discusses the International Air Transport Association Aviation Working Group's “Guidance Material on Microbiological Contamination in Aircraft Fuel Tanks”.

Bio‐ecological drainage system (BIOECODS) for water quantity and quality control

Land use change in urbanizing watersheds can have a significant impact on hydrologic and hydraulic process as well a degradation of water quality on receiving waters. The Bio‐Ecological Drainage System (BIOECODS) consists of elements of storage, flow retarding and infiltration engineering. Swales, dry ponds, detention ponds and wetland are the main components of BIOECODS that function as flow attenuation and water quality treatment devices. The BIOECODS is a pilot project that meets the requirements of the Stormwater Management Manual for Malaysia and has been constructed at the Engineering Campus of the University Science Malaysia, Nibong Tebal, Penang. BIOECODS represents an alternative to the traditional hard engineering‐based drainage system to manage stormwater quantity and quality for urban areas. This article discusses how the BIOECODS could be implemented to control stormwater quantity from an urbanized area and reduce the water quality impact on the receiving water.

Beyond Perception: The Experience of Risk and Stigma in Community Contexts

Concerns about stigmatization are an important influence on the development of risk management and communication policies for a wide range of technologies and products such as those associated with hazardous waste storage, nuclear power, and genetic engineering of plants or foods. Although much attention has been placed on the adverse economic effects of stigma, we believe that the social, psychological, and cultural impacts are often at least as significant and merit greater attention from policymakers and researchers. Evidence for these impacts of stigma is found in recent studies of resource-based communities, whose residents may be shunned by local and nonlocal publics and whose products may suffer a loss of markets, which in turn creates social and economic hardship for community residents. We examine these aspects of stigma and link descriptions of the problem and prescriptions of recommended policies to five underlying characteristics of stigma, focusing on the possible insights and contributions from trade-off analysis and narrative approaches.

Preparation of Mesoporous High-Surface-Area Activated Carbon

A simple, cost effective method for producing carbons with high mesopore contentis presented. The effect of the ratio of activating agent (ZnCl2) to carbon precursor (coconut shell) on pore size is investigated as is the nitrogen adsorption isotherm of these carbonaceous materials at 77 K. The mesoporosity is substantiated by the absorption capacity for phenol, methylene blue, and erythrosine red. Mesoporous high-surface-area activated carbons, which up to now have proved difficult to prepare, have applications as catalytic, battery electrode, capacitor, gas storage, and biomedical engineering materials.

DataExchange: High performance communications in distributed laboratories

Current communications tools and libraries for high performance computing are designed for platforms and applications that exhibit relatively stable computational and communication characteristics. In contrast, the demands of (1) mixed environments in which high performance applications interact with multiple end users, visualizations, storage engines, and I/O engines – termed `distributed laboratories' in our research – and (2) high performance collaborative computing applications in general, exhibit additional complexities in terms of dynamic behaviors. This paper explores the communication requirements of distributed laboratories, and it describes the DataExchange communication infrastructure supporting high performance interactive and collaborative applications.

Cold Thermal Storage and Cryogenic Heat Engines for Energy Storage Applications

A theoretical analysis is presented of heat engines that use the atmosphere as a hot reservoir and a cryogenic medium as a cold reservoir. These “cryogenic” heat engines can be used as zero emission power sources and are found to have unexpectedly large specific work (work per unit mass of the cold reservoir) values when gases of low atomic mass are used as the cryogenic medium.

Evolution of data management

Computers can now store all forms of information: records, documents, images, sound recordings, videos, scientific data, and many new data formats. Society has made great strides in capturing, storing, managing, analyzing, and visualizing this data. These tasks are generically called data management. This article sketches the evolution of data management systems. There have been six distinct phases in data management. Initially, data was manually processed. The next step used punched-card equipment and electromechanical machines to sort and tabulate millions of records. The third phase stored data on magnetic tape and used stored-program computers to perform batch processing on sequential files. The fourth phase introduced the concept of a database schema and on-line navigational access to the data. The fifth step automated access to relational databases and added distributed and client server processing. We are now in the early stages of sixth-generation systems that store richer data types, notably documents, images, voice, and video data. These sixth-generation systems are the storage engines for the emerging Internet and intranets. Early data management systems automated traditional information processing. Today they allow fast, reliable, and secure access to globally distributed data. Tomorrow's systems will access and summarize richer forms of data. It is argued that multimedia databases will be a cornerstone of cyberspace.

RRR measurements on a SMES-ETM mockup superconductor

An unconventional, easy to perform method is used to determine the in situ residual resistivity ratio (RRR) of the major stabilizer region of superconductive magnetic energy storage (SMES) engineering test magnet (ETM) 60,000 amp composite superconductor. Measurements are taken by the eddy current decay (ECD) method. A primary benefit of the ECD technique is that measurements are possible at 4.2 K with superconducting filaments present. By taking measurements at 4.2 K and room temperature, the stabilizer RRR can be determined without concern for conductor geometry. Results show that this method holds promise as a tool for monitoring the residual resistivity of heavily stabilized superconductors under normal operating circumstances (wound into a magnet and below T/sub c/).< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Structure and cost scaling for intermediate size superconducting magnetic energy storage (SMES) systems

The Superconducting Magnetic Energy Storage (SMES) Engineering Test Model (ETM) was sized to be extrapolated to a full-scale utility system and only warm structural support was practical. If this constraint is removed, then smaller systems structurally reinforced with cold mass are more cost effective than supported with warm mass. Higher field is also more advantageous and thus the bore of a 20 MWh magnet is an order of magnitude smaller than an ETM. Both aluminum and stainless steel supports were considered and the weight of 1-100 MWh systems were determined. The cost of the SMES magnet scales as 0.5 power of stored energy. The cross over in stored energy where magnets supported by warm structures becomes cheaper was also determined.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Micromechanical structures for data storage

Rapidly increasing demand for data storage continues to drive the storage industry in a primary technological trend: the areal data density of the stored information must also increase at a very high rate. Micromechanical structures are soon likely to be needed to accommodate the increased mechanical positioning precision necessary for reading and writing data, as the bit and track sizes continue to decrease. Furthermore, as one considers storage densities beyond magnetic or optical limits, micromechanical devices will be needed to extend storage capacity through the use of advanced recording mechanisms. A first example of micromechanical engineering for data storage is a microactuator used as the fine stage of a two-stage actuator to position a magnetic recording head. Using the microactuator, the head can be positioned more rapidly and precisely, than can be accomplished by a conventional voice coil motor-driven, single-stage actuator. This device is a lithographically-defined, high-aspect-ratio, electroplated structure which is electrostatically-driven. The fabrication process and mechanical characteristics are described for the device, which may have linear or rotary motion. A micromechanical scanning probe structure, which may represent the basis for future directions for data storage, is also described. An Atomic Force Microscope (AFM)-based probe device is used to generate and detect fine pits in a polymer storage medium, using a probe-heating laser and a motion-detection laser. An areal density of 25 Gb/in 2 is achieved, along with a data reading rate of about 1 Mb/s. Key to this level of performance is the incorporation of an extremely low-mass (0.3 ng) AFM probe, having a spring constant of about 1 N/m. Probe fabrication and associated performance are given.

Quench initiation and propagation study (QUIPS) for the SMES-CICC

A test coil was designed and built in order to experimentally verify the quench initiationand propagation behavior in a sub-scale version of the 200 kA cable-in-conduit conductor (CICC) for the superconducting magnetic energy storage (SMES) Engineering Test Model (ETM). A test coil was wound with 75 m of a sub-scale (nominal 8 kA) conductor. The sub-scale conductor reproduced the hydraulic characteristics of the 200 kA CICC (a cable space and a segregated open flow path communicating through a perforated wall). The quench tests, conducted at the National High Magnetic Field Laboratory, are the first done in this type of geometry and in 1.8 K superfluid helium. The results of the experiment shed new light on the mechanisms driving the quench propagation in this type of conductor, and show that the behavior is inherently different from that in standard CICCs (without segregated channel).

Key design selections for the 20.4 MWh SMES/ETM

The 20.4-MWh superconducting magnetic energy storage engineering test model (SMES/ETM) will be the world's largest superconducting magnet by nearly two orders of magnitude in stored energy. Its size, Lorentz loads, and power delivery requirements dictate a number of fundamental design requirements. In addition, the SMES/ETM must fully accomplish its primary mission of demonstrating large-scale SMES technology, while at the same time minimizing technical, schedule, and cost risks. A discussion is presented of nine key design decisions that are fundamental to meeting these challenging goals. These are a conductor current of 200 kA, helium containment within the conductor, an operating temperature of 1.8 K, a CICC conductor with a hollow core, a conductor premanufactured in half-turn lengths, a circular and continuous coil pac structure, fiberglass-reinforced plastic pultrusion for the coil pack structure material, a coil pack operating position that is precompressed radially inward, and a liner for vacuum enclosure.

Coil protection for the 20.4 MWh SMES/ETM

The 20.4-MWh superconducting magnetic energy storage engineering test model (SMES/ETM) is large and stores nearly two orders of magnitude more energy than any man-made magnet to date. These characteristics pose unique requirements for coil protection in response to a normal zone. A method of detecting a normal zone, action taken to quench the coil, and the subsequent temperature and voltage response of the coil pack are presented. It is shown that a normal zone produces a significant resistive voltage that can be easily detected, the coil is driven normal at half-turn intervals by inductive heaters, and coil response is calculated to be benign, both thermally and electrically.

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Geological hazards and water storage

About 1 percent of the 9000 large dams in service throughout the world during the period 1900–1965 have failed and another 2 percent have suffered serious accidents. In more than 50 percent of these cases the damage could be related to geological causes. This Paper presents brief analyses of 9 projects which have been seriously affected by incidents related to geological causes and derives for each project a list of factors which are judged to have contributed to the incidents. It is shown that a significant number of incidents have occurred due to technological factors which were either unknown or inadequately understood at the time of design or construction of the project. It is concluded that there are undoubtedly still some unknown geotechnical factors in water storage engineering and that designs should continue to allow for this situation. The other contributing factors are mostly concerned with deficiencies in the application of geological science to civil engineering. To overcome such deficiencies an objective-oriented site investigation approach is outlined in which geological methods are applied together with engineering methods, to provide answers to various engineering questions. These questions mostly relate to possible changes to the site environment resulting from construction and operation of the project, and in particular to possible modes of failure of the project. It is considered important that geological data for water storage projects should be obtained in such a systematic manner and that the geological input be provided by experienced geologists with appreciable engineering knowledge. This knowledge may be gained partly from tertiary education institutions but should always include that gained from experience while working closely with geotechnical, design and construction engineers, on construction jobs.