scholarly journals A simulation of distributed STM

2018 ◽  
Vol 15 (1) ◽  
pp. 85-95
Author(s):  
Dragan Brkin ◽  
Branislav Kordic ◽  
Miroslav Popovic
Keyword(s):  
Data Center ◽  
Transactional Memory ◽  
System Behavior ◽  
Two Phase ◽  
Future Work ◽  
Commit Protocol

This paper presents an extension of the IaaS Cloud simulator CloudSim. Computational tasks are modeled in the form of a transaction on a transactional memory and communication between the data center is based on the Two-Phase Commit protocol. The model of the distributed STM prototype is implemented using the extended CloudSim simulator. The obtained results are as expected and in accordance with desired system behavior. The presented results are positive and they stimulate future work in development of distributed STM.

Performance of a two-phase commit protocol

1996 ◽  
Vol 38 (9) ◽  
pp. 581-599 ◽  
Author(s):  
Bipin C. Desai ◽  
Boutros S. Boutros
Keyword(s):  
Two Phase ◽  
Commit Protocol

Embedded Two-Phase Cooling of High Flux Electronics via Micro-Enabled Surfaces and Fluid Delivery Systems (FEEDS)

2015 ◽  
Author(s):  
Raphael Mandel ◽  
Serguei Dessiatoun ◽  
Patrick McCluskey ◽  
Michael Ohadi
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Saturation Temperature ◽  
Absolute Pressure ◽  
High Flux ◽  
Vapor Quality ◽  
Two Phase ◽  
Fluid Delivery ◽  
Future Work

This work presents the experimental design and testing of a two-phase, embedded manifold-microchannel cooler for cooling of high flux electronics. The ultimate goal of this work is to achieve 0.025 cm2-K/W thermal resistance at 1 kW/cm2 heat flux and evaporator exit vapor qualities at or exceeding 90% at less than 10% absolute pressure drop. While the ultimate goal is to obtain a working two-phase embedded cooler, the system was first tested in single-phase mode to validate system performance via comparison of experimentally measured heat transfer coefficient and pressure drop to the values predicted by CFD simulations. Upon validation, the system was tested in two phase mode using R245fa at 30°C saturation temperature and achieved in excess of 1 kW/cm2 heat flux at 45% vapor quality. Future work will focus on increasing the exit vapor quality as well as use of SiC for the heat transfer surface upon completion of current experiments with Si.

scholarly journals Concurrency Control in Database Systems

2019 ◽  
Vol 1 (2) ◽  
pp. 26-40
Author(s):  
Dardina Tasmere ◽  
Md. Nazmus Salehin
Keyword(s):  
Concurrency Control ◽  
Phase Locking ◽  
Wait Time ◽  
Arrival Rate ◽  
Database Systems ◽  
Control Algorithms ◽  
Control Mechanisms ◽  
Time Stamp ◽  
System Behavior ◽  
Two Phase

Concurrency control mechanisms including the wait, time-stamp and rollback mechanisms have been briefly discussed. The concepts of validation in optimistic approach are summarized in a detailed view. Various algorithms have been discussed regarding the degree of concurrency and classes of serializability. Practical questions relating arrival rate of transactions have been presented. Performance evaluation of concurrency control algorithms including degree of concurrency and system behavior have been briefly conceptualized. At last, ideas like multidimensional timestamps, relaxation of two-phase locking, system defined prewrites, flexible transactions and adaptability for increasing concurrency have been summarized.

A Two-Phase Load Balancing Algorithm for Cloud Environment

2021 ◽  
Vol 13 (1) ◽  
pp. 38-55
Author(s):  
Archana Singh ◽  
Rakesh Kumar
Keyword(s):  
Load Balancing ◽  
Data Center ◽  
Virtual Machines ◽  
Second Phase ◽  
Cloud Environment ◽  
Cloud Platform ◽  
Efficient Utilization ◽  
Two Phase ◽  
Excessive Load ◽  
Load Balancing Algorithm

Load balancing is the phenomenon of distributing workload over various computing resources efficiently. It offers enterprises to efficiently manage different application or workload demands by allocating available resources among different servers, computers, and networks. These services can be accessed and utilized either for home use or for business purposes. Due to the excessive load on the cloud, sometimes it is not feasible to offer all these services to different users efficiently. To solve this excessive load issue, an efficient load balancing technique is used to offer satisfactory services to users as per their expectations also leading to efficient utilization of resources and applications on the cloud platform. This paper presents an enhanced load balancing algorithm named as a two-phase load balancing algorithm. It uses a two-phase checking load balancing approach where the first phase is to divide all virtual machines into two different tables based on their state, that is, available or busy while in the second phase, it equally distributes the loads. The various parameters used to measure the performance of the proposed algorithm are cost, data center processing time, and response time. Cloud analyst simulation tool is used to simulate the algorithm. Simulation results demonstrate superiority of the algorithm with existing ones.

Macrosegregation Caused by Deformation of the Mushy Zone

2006 ◽  
Vol 508 ◽  
pp. 187-192 ◽  
Author(s):  
Lilia C. Nicolli ◽  
Christophe L. Martin ◽  
Asbjørn Mo ◽  
Olivier Ludwig
Keyword(s):  
Mushy Zone ◽  
Experimental Test ◽  
Continuum Model ◽  
Interdendritic Liquid ◽  
Outer Part ◽  
Selected Lines ◽  
Two Phase ◽  
Set Up ◽  
Future Work

An experimental set-up for investigating macrosegregation formation due to deformation of an isotropic metallic mushy zone is presented. In the experiment, a semisolid Al-5.9wt%Cu sample is isothermally and non-uniformly compressed. Concentration and eutectic fraction are measured along selected lines, after quenching the sample. Results show that interdendritic liquid is pressed out of the central part of the sample to its outer part, increasing the concentration in this region. The experimental test is then addressed by a two-phase continuum model recently presented elsewhere. The modelling results show the same tendencies observed experimentally, although local variations in composition are not well correlated. Suggestions for future work are made.

Two-Phase Transpiration Cooling

1982 ◽  
Author(s):  
M. A. El-Masri
Keyword(s):  
Gas Turbine ◽  
Transpiration Cooling ◽  
System Behavior ◽  
Two Phase ◽  
Modes Of Operation ◽  
Considerable Potential ◽  
Closed Form Solutions ◽  
Turbine Cooling ◽  
Gas Turbine Cooling ◽  
Hot Surface

Two-phase transpiration is shown to possess considerable potential for gas turbine cooling. In this concept, water fed into a porous component boils within the wall. The resulting steam issues from the hot surface forming the transpiration film. A model for the performance of such a system is developed. Assuming constant properties and a linear reduction of Stanton number with transpiration rate, closed-form solutions are obtained. The governing dimensionless parameters are identified, the system behavior predicted, and the modes of operation delineated. Those are defined as two-phase, partially-flooded, and completely-flooded modes. At low values of a certain “modified Peclet number,” the two-phase mode is unstable and the system tends to flood. Large values of this parameter indicate stable, well-regulated behavior. Discussions on gas turbine applications are presented. A typical numerical example is given in the Appendix.

Biodegradation of phenol at low temperature using two-phase partitioning bioreactors

2005 ◽  
Vol 52 (10-11) ◽  
pp. 97-105 ◽  
Author(s):  
B. Guieysse ◽  
Y. Autem ◽  
A. Soares
Keyword(s):  
Low Temperature ◽  
Aqueous Phase ◽  
Negative Impact ◽  
Phenol Degradation ◽  
Pollutant Removal ◽  
Two Phase ◽  
Phenol Biodegradation ◽  
Phase Partitioning ◽  
Volumetric Rate ◽  
Future Work

Two-phase partitioning bioreactors offer many advantages for the removal of toxic pollutants. In particular, such systems can be loaded with very large quantities of pollutants without risks of microbial inhibition, they are self-regulated and they prevent the risks of hazardous pollutant volatilisation during aerobic treatment. However, their potential has never been tested at low temperatures. Phenol biodegradation by a cold adapted Pseudomonas strain was therefore tested at 14 or 4°C using 2-undecanone, diethyl sebacate or 2-decanone as organic phases in a two-phase partitioning bioreactor. The three solvents were biocompatible at 14°C but evidence was found that diethyl sebacate was biodegraded by the bacteria and this solvent was not tested further. Although only 2-decanone was suitable at 4°C, phenol biodegradation was more efficient in 2-undecanone at 14°C, reaching a maximum volumetric rate (based on the volume of aqueous phase) of approximately 1.94g/L·day after 47h of cultivation. In 2-decanone at 14°C, evidence was found that phenol degradation was limited by the release of biosurfactants, which increased the solubility and toxicity of the solvent in the aqueous phase inhibiting microbial activity. This study therefore shows that pollutant removal at low temperature is feasible but that the production of biosurfactants can have a negative impact on the process and must be taken into consideration when selecting the organic solvent. Future work should therefore focus on the selection of solvents suitable for use at temperatures below 14°C.

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