Serializable Snapshot Isolation in PostgreSQL

This paper describes our experience implementing PostgreSQL's new serializable isolation level. It is based on the recently-developed Serializable Snapshot Isolation (SSI) technique. This is the first implementation of SSI in a production database release as well as the first in a database that did not previously have a lock-based serializable isolation level. We reflect on our experience and describe how we overcame some of the resulting challenges, including the implementation of a new lock manager, a technique for ensuring memory usage is bounded, and integration with other PostgreSQL features. We also introduce an extension to SSI that improves performance for read-only transactions. We evaluate PostgreSQL's serializable isolation level using several benchmarks and show that it achieves performance only slightly below that of snapshot isolation, and significantly outperforms the traditional two-phase locking approach on read-intensive workloads.Comment: VLDB201

Dual motion valve with single motion input

A dual motion valve includes two dual motion valve assemblies with a rotary input which allows the benefits of applying both rotary and axial motion to a rotary sealing element with a plurality of ports. The motion of the rotary sealing element during actuation provides axial engagement of the rotary sealing element with a stationary valve plate which also has ports. Fluid passages are created through the valve when the ports of the rotary sealing element are aligned with the ports of the stationary valve plate. Alignment is achieved through rotation of the rotary sealing element with respect to the stationary valve plate. The fluid passages provide direct paths which minimize fluid turbulence created in the fluid as it passes through the valve

Key factors and barriers to the adoption of cold ironing in europe

The first cases of successful implementation of cold ironing can be found in Alaska about twenty years ago. In that case, the energy cost was lower than in Europe where cold ironing has been developed only in the latest years at few ports. The present paper investigates the innovative process of cold ironing at European level. Firstly, its recent development in Europe is documented as well as the main concern of its corresponding legislation. Then, the adoption of this initiative by the “green ports” concept is discussed. Secondly, the technical barriers, such as lack of standardization of electricity parameters are mentioned. And given that port electrical infrastructure needed onshore represents a huge investment that not all ports are financially able to do, the financial problematic is treated explicitly taking into account the cost of energy at ports (directly provided by electric centrals or converted) against the energy cost onboard. Finally, conclusions are drawn covering the main barriers confronted by this technology and the future premises of cold ironing at European ports considering the social and environmental benefits in terms of air and noise pollution.cold ironing, energy cost, technology barrier, European ports, environmenta

Regis-Darwin specified in the p-Calculus

There now is a translator for DARWIN programs that automatically generates their π-calculus equivalents. A variety of errors in DARWIN programs can be detected at the π-calculus level. These include detection of recursive structures, unbound ports and ports that are bound in the wrong direction. It can also be used to confirm whether two REGIS-DARWIN programs are equivalent

Maritime Commerce in Greater Philadelphia: Assessing Industry Trends and Growth Opportunities for Delaware River Ports

Maritime Commerce in Greater Philadelphia: Assessing Industry Trends and Growth Opportunities for Delaware River Ports is an evaluation of existing port conditions along the Delaware River and market-driven opportunities for expansion. The report includes an economic impact analysis, Delaware River port descriptions, global trends, and recommended strategies for ports growth. Key findings include:Region-wide port activity generates $69 million in tax revenues for state governments across Greater Philadelphia and more than$11 million in Philadelphia Wage Tax revenues.Each on-site port job supports two jobs from port activity and employee spending. Total regional port-related employment is 12,000+ jobs.Delaware River ports import nearly 1/2 of the nation's cocoa beans, almost 1/3 of the bananas, and a 1/4 of all fruit and nuts.Growing maritime commerce in Greater Philadelphia will require collaboration among Delaware River ports to leverage existing strengths and strategically invest in regional infrastructure improvements

A valve concept for remote fluid flow control

Valve concept has been devised which offers lightweight, simplified mechanism capable of automatic control of large number of fluid flow ports. Valve control is achieved with valve stem which is bimetallic device activated by heating coil to open or close selected supply port. Number of controlled ports is limited only by desired physical size of system

Photon number conservation and photon interference

The group theoretical aspect of the description of passive lossless optical four-ports (beam splitters) is revisited. It is shown through an example, that this approach can be useful in understanding interferometric schemes where a low number of photons interfere. The formalism is extended to passive lossless optical six-ports, their SU(3)-theory is outlined.Comment: Contribution at "Classical and Quantum Interference" workshop in RCO, Olomouc, Oct. 25-26 2001. A corrected versio

Harmonically-related diffraction gratings-based interferometer for quadrature phase measurements

We demonstrate the use of shallow diffraction gratings for quadrature phase interferometry. A single shallow diffraction grating-based Michelson interferometer yields only trivial (0° or 180°) phase shift between different output ports. In comparison, a combination of two parallel shallow diffraction gratings can be useful to achieve desired phase shifts (e.g., 90° for quadrature phase interferometry). We show that the phase at different output ports of a grating-pair based interferometer can be adjusted by shearing the two gratings with respect to each other. Two harmonically-related diffraction gratings are used to demonstrate phase shift control at the output ports of a modified Michelson interferometer. Our experimental data is in good agreement with theory

Parametric Macromodels of Digital I/O Ports

This paper addresses the development of macromodels for input and output ports of a digital device. The proposed macromodels consist of parametric representations that can be obtained from port transient waveforms at the device ports via a well established procedure. The models are implementable as SPICE subcircuits and their accuracy and efficiency are verified by applying the approach to the characterization of transistor-level models of commercial devices