OMEGA evaluation

Andersen, K. E Lau, J., Lundt, B. F Petersen, H Huusfeldt, P. 0., Suzdak, P. D., and Swedberg, M. D. (2001) Synthesis of novel GABA uptake inhibitors. Part 6 preparation and evaluation of N-Omega asymmetrically substituted nipecotic acid derivatives. Bioorg. Med. Chem. 9,2773-2785. 

T. Takahashi, S. Nishimura, T. Ido, K. Ishiwata, R. Iwata, Biological evaluation of 5-methyl-branched-chain omega-[ F]-fluorofatty acid A potential myocardial imaging tracer for positron emission tomography, Nucl. Med. Biol. 23 (1996) 303-308. 

CN143 Rao, R., and B. R. Lokesh. Nutritional evaluation of structured lipid containing omega 6 fatty acid synthesized from coconut oil in rats. Mol Cell Biochem 2003 248(1-2) 25-33. 

This can be evaluated using the Omega method, if applicable (see Annex 8) or other HEM model (see Annex 4). The Omega method can be used to obtain G and the exit choke pressure, PE for the upstream pipe. An isenthalpic flash calculation can then be performed from the stagnation pressure at the start of the pipe to the choke pressure, PE, in order to evaluate the mass fraction of vapour, x, at the pipe exit. If the flow is not choked, then the term (PE - Pa) becomes zero. 

DIERS[1) presented a series of design charts, based on the Omega method, which can be used to evaluate the thrust force. These charts do not include the dynamic load factor, FD. If a load is suddenly applied, as will be the case following operation of a relief system, the piping will. experience a dynamic load of approximately twice the applied load. It is therefore usual to use a dynamic load factor of 2 in equation (12.1). Leung121 also discusses the use of the Omega method to calculate reaction forces. 

The Omega method calculates the two-phase flow capacity per unit area, G, of a nozzle or pipe of constant diameter. It evaluates the homogeneous equilibrium model (see 9.4.1) for two-phase flow. The Omega method is particularly convenient, when applicable, because it does not require the use of a computer. All properties can often be evaluated at the conditions in the upstream vessel, (which are known). Most other methods to evaluate G for two-phase flow require the use of appropriate computer codes (see Annex 4). Exceptions are given in 9.4. 

Omega is a correlating parameter in an "equation of state" (EOS) which links the specific volume of a two-phase mixture flowing in a relief system with the pressure at any point. Such an EOS is required to evaluate the HEM without performing repeated flash calculations. The EOS used by the Omega method is ... 

The above conditions of applicability apply even when the Omega parameter is evaluated by the most accurate method, i.e. using equation (A8.4) and making use of computerised physical property calculations. Alternatively, simplified equations for evaluating Omega can also be used (equations (A8.5) to (A8.10)). These introduce a further condition of applicability ... 

Omega can be evaluated directly from the EOS for the Omega method (see equation... 

It will not always be possible to use the more accurate definition given in equation (A8.4) above, for example in cases where the required physical property data would be difficult to generate. In such cases, the following alternative approximate definitions of Omega have been proposed[3,4,51. However, the additional condition of applicability (h) in A8.2 needs to be considered before their use. Omega can be calculated by any of equations (A8.5) to (A8.10) below, which are essentially equivalent. In these equations, Omega is evaluated entirely at the conditions in the upstream reactor. ... 

Equations such as (A8.11) have wider applicability because they do not require the Clausius-Clapeyron relationship to hold and they should, therefore, be applicable for wider boiling mixtures. However, all of the approximate equations given in this section are evaluated only at the conditions in the upstream reactor. This reduces their accuracy if the pressure drop is high (e.g. if there is a piping system with substantial pressure drop). In such cases, equation (A8.4) is to be preferred. Alternatively, different calculation methods to the Omega method can be used. 

The evaluation of G in a rigorobs way using the Omega method for non-choked flow in the presence of friction and static head change requires the solution of an integral equation (equation (21) of reference 5). This can.be time-consuming. 

J C Leung, "The Omega Method for Discharge Rate Evaluation", International Symposium on Runaway Reactions and Pressure Relief Design, 367-393, AlChE, 1995, ISBN 0-8169-0676-9... 

Feeding of animals in general can enhance the omega-3 levels in lipids and is well documented. In contrast, few studies have documented the stability of the lipids in stored meats or in processed meat products. Additional researcher is needed to evaluate the sensory characteristics of stored meats and of processed meat products containing enhanced omega-3 lipids. 

Evaluation of potentially useful antimanic agents continues. Studies are in progress to determine whether other novel antipsychotics and anticonvulsants are effective. Omega-3 fatty acids, contained in large amounts in certain fish oils, have been reported in several publications as effective agents as well. Further research on these compounds is needed before determining their true value in antimanic therapy. 

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