A Review Of Multi-Tenant Database And Factors That Influence Its Adoption.

A Multi-tenant database (MTD) is a way of deploying a Database as a Service (DaaS). This is gaining momentum with significant increase in the number of organizations ready to take advantage of the technology. A multi-tenant database refers to a principle where a single instance of a Database Management System (DBMS) runs on a server, serving multiple clients organizations (tenants). This is a database which provides database support to a number of separate and distinct groups of users or tenants. This concept spreads the cost of hardware, software and other services to a large number of tenants, therefore significantly reducing per tenant cost. Three different approaches of implementing multi-tenant database have been identified. These methods have been shown to be increasingly better at pooling resources and also processing administrative operations in bulk. This paper reports the requirement of multi-tenant databases, challenges of implementing MTD, database migration for elasticity in MTD and factors influencing the choice of models in MTD. An insightful discussion is presented in this paper by grouping these factors into four categories. This shows that the degree of tenancy is an influence to the approach to be adopted and the capital and operational expenditure are greatly reduced in comparison with an on-premises solutio

Nationalistic Elements in Farming on the Lake Plains of Northwestern Ohio

Author Institution: Ohio State Universit

Global analysis of carbon disulfide (CS2) using the 3-D chemistry transport model STOCHEM

Carbon disulfide (CS₂), a precursor to the long-lived carbonyl sulphide (OCS) is one of the main contributors to the atmospheric sulfate layer. The annual fluxes from its sources and sinks are investigated using a 3-D chemistry transport model, STOCHEM-CRI. In terms of the flux analysis, the oxidation of CS₂ by OH is found to be the main removal process (76–88% of the total loss) and the dry deposition loss contributes 11–24% to the total loss of CS₂. The global burden of CS₂ was calculated, varying between 6.1 to 19.2 Tg and the lifetime of CS₂was determined to be within the range of 2.8–3.4 days. The global distribution of CS₂ found the Northern Hemisphere (NH) continental landmasses to be the areas of concentration maxima with peak concentrations reaching up to 20 ppt during June-July-August (J-J-A) season and 40 ppt during December-January-February (D-J-F) season in anthropogenic source regions. Oceanic regions returned low CS₂ levels of less than 2 ppt. The vertical profile of CS₂ shows higher levels up to 3 ppt at 30°N–45°N during J-J-A and up to 4 ppt at 30°N–55°N during D-J-F. The oxidation of CS₂by OH can produce a substantial amount (0.58 Tg/yr) of atmospheric OCS and the annual average surface distribution of this flux shows up to 6 Gg/yr OCS formed in the regions with highest anthropogenic pollution (e.g., South east Asia). In general, the model-measurement comparison reveals an underprediction of model CS₂ compared with measured CS₂ for most of the regions. It is likely that the emissions of CS₂ are being underestimated and there are likely much larger emission sources of atmospheric CS₂ than previously suggested

Combining Binary Decision Diagrams and Backtracking Search for Scalable Backtrack-Free Interactive Product Configuration

The impact of the formation of HO2-H2O adducts following reaction between H2O and HO2 and subsequent reaction of this adduct on HOx, H2O2 and O3 as a function of relative humidity in the marine boundary layer has been investigated using a zero-dimensional box model. The results of simulations with different product yields for the reaction of HO2-H2O with HO2 were compared with base case data derived from current recommendations for tropospheric modelling. It is suggested that inclusion of reactions of the HO2-H2O adduct may provide a significant sink for HO2 which has so far not been considered in models of tropospheric chemistry and depending on reaction products may have a significant impact on H2O2 and O3

Abundance of NO3 derived organo-nitrates and their importance in the atmosphere

The chemistry of the nitrate radical and its contribution to organo-nitrate formation in the troposphere has been investigated using a mesoscale 3-D chemistry and transport model, WRF-Chem-CRI. The model-measurement comparisons of NO2, ozone and night-time N2O5 mixing ratios show good agreement supporting the model’s ability to represent nitrate (NO3) chemistry reasonably. Thirty-nine organo-nitrates in the model are formed exclusively either from the reaction of RO2 with NO or by the reaction of NO3 with alkenes. Temporal analysis highlighted a significant contribution of NO3-derived organo-nitrates, even during daylight hours. Night-time NO3-derived organo-nitrates were found to be 3-fold higher than that in the daytime. The reactivity of daytime NO3 could be more competitive than previously thought, with losses due to reaction with VOCs (and subsequent organo-nitrate formation) likely to be just as important as photolysis. This has highlighted the significance of NO3 in daytime organo-nitrate formation, with potential implications for air quality, climate and human health. Estimated atmospheric lifetimes of organo-nitrates showed that the organo-nitrates act as NOx reservoirs, with particularly short-lived species impacting on air quality as contributors to downwind ozone formation