The fully implicit finite-difference method is used to solve the continuity, momentum, and energy equations for flow within a gas pipeline. This methodology (1) incorporates the convective inertia term in the conservation of momentum equation, (2) treats the compressibility factor as a function of temperature and pressure, and (3) considers the friction factor as a function of the Reynolds number and pipe roughness. The fully implicit method representation of the equations offers the advantage of guaranteed stability for a large time step, which is very useful for gas pipeline industry. The results show that the effect of treating the gas in a nonisothermal manner is extremely necessary for pipeline flow calculation accuracies, especially for rapid transient process. It also indicates that the convective inertia term plays an important role in the gas flow analysis and cannot be neglected from the calculation.

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A detailed mathematical model of compressor stations and pipes is essential for optimizing the performance of the gas pipeline system. Most of the available literature on compressor station modeling is based on isothermal solutions for pipe flow, which is inadequate for our purposes. In the present work, the pipe flow is treated as nonisothermal unsteady one-dimensional compressible flow. This is accomplished by treating the compressibility factor as a function of pressure and temperature, and the friction factor as a function of Reynolds number. The solution method is the fully implicit finite difference method that provides solution stability, even for relatively large time steps. The compressors within the compressor station are modeled using centrifugal compressor map-based polynomial equations. This modeling technique permits the designation of different models of compressors in the compressor station. The method can be easily extended to include other types of compressors. Using this mathematical model as a basis, a nonlinear programing problem (NLP) is set up wherein the design variables are the compressor speeds and the objective function to be minimized is the total fuel consumption. The minimum acceptable throughput is imposed as a constraint. This NLP is solved numerically by a sequential unconstrained minimization technique, using the mathematical model of the system for the required function evaluations. The results show that this approach is very effective in reducing fuel consumption. An application of this methodology for selecting the number of compressors to be shut down for the most fuel-efficient operation is also presented. Our results further indicate that station-level optimization produces results comparable to those obtained by network-level optimization. This is very significant because it implies that the optimization can be done locally at the station level, which is computationally much easier.

Non steroidal anti-inflammatory drugs (NSAID's) are first line therapeutic agents for the treatment of arthritis. NSAID's reduce the pain and swelling associated with arthritis by blocking the metabolism of arachidonic acid (AA) through the enzyme cyclooxygenase (COX) and thereby the production of prostaglandins, e.g. PGE 2 , which sensitizes nociceptors at nerve fiber terminals. 1,2) Additionally, the 5-lipoxygenase (5-LO) products such as leukotriene B 4 (LTB 4 ) also contributes to the hyperalgesia seen during inflammation by decreasing the mechanical and thermal thresholds of C fiberes.3) Leukotrienes, especially LTB 4 together with prostaglandins are implicated in the acute ulceration induced by NSAID's. 4) For these reasons, compounds that achieve dual inhibition of enzymes COX and 5-LO reduce side effects and improved efficacy in the combat of pain in inflammatory diseases.5) Some evidences suggest that the hydrazone moiety present in phenylhydrazone derivative 1 (Fig. 1), possesses a pharmacophoric character for the inhibition of COX and hydrazone type containing compounds such as compound 2 (Fig. 1) were described as dual COX/5-LO inhibitors.6,7) According to these evidences, there are some reports about synthesis and pharmacological evaluation of new bioactive compounds with N-aroylarylhydrazone structure acting at the AA cascade enzyme level (Fig. 2, compounds 3-5). [8][9][10] On the basis of these reports, we described previously the synthesis and analgesic profile of Narylhydrazone derivatives of mefenamic acid 6 (Fig. 3), a known NSAID drug with fenamate structure.11) Most of these synthesized compounds were effective as analgesic agents in comparison to control and showed more analgesic activity in comparison to mefenamic acid. In fact, compound 7 (Fig. 3) displayed 3.6-fold greater potency than mefenamic acid as an analgesic agent, in a model of abdominal constrictions induced by acetic acid. These results led us to design new structurally related derivatives 10, 11. Target compounds 10, 11 were obtained according to Chart 1. The starting hydrazides 8 (XϭO, RϭH and XϭNH, RϭH) were prepared by the known procedures and hydrazide 8 (XϭO, RϭCl) was synthesized as described previously.12-17) Compounds 10, 11 were synthesized by acid-catalyzed condensation of hydrazides 8 with corresponding substituted benzaldehydes or acetophenones.10,11) The synthesis and antimicrobial activity A series of 2-phenoxybenzoic acid and N-phenylanthranilic acid hydrazides were synthesized and evaluated for their analgesic activities. Several compounds were significantly more potent than mefenamic acid and diclofenac sodium in abdominal constriction and formalin tests.

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