Les Pré-(a b)-algèbres à Homotopie Près

Dans cet article on étudie le concept d'algèbre à homotopie près pour une structure définie par deux opérations ? et ?. Des exemples importants d'une telle structure sont ceux des algèbres pré-Gerstenhaber et pré-Poisson graduées. Etant donnée une structure d'algèbre pré-commutative et pré-Lie graduée pour deux décalages des degrés donnés par a et b, on définit la structure d'une pré-(a, b)-algèbre graduée et on donne une construction explicite de l'algèbre à homotopie près associée.

We study in this article the concept of algebra up to homotopy for a structure defined by two operations, ? and ?. Important examples of such structure are those of graded pre-Gerstenhaber and pre-Poisson algebras.

Given a structure of pre-commutative and pre-Lie algebra for two shifts of degree given by a and b, we define the structure of a graded pre-(a, b)-algebra, and we give an explicit construction of the associated algebra up to homotopy     

Active vibration control on a quarter-car for cancellation of road noise disturbance

In this paper, a methodology is presented for the cancellation of road noise, from the analysis of vibration transmission paths for an automotive suspension to the design of an active control system using inertial actuators on a suspension to reduce the vibrations transmitted to the chassis. First, experiments were conducted on a Chevrolet Epica LS automobile on a concrete test track to measure accelerations induced on the suspension by the road. These measurements were combined with experimental Frequency Response Functions (FRFs) measured on a quarter-car test bench to reconstruct an equivalent three dimensional force applied on the wheel hub. Second, FRFs measured on the test bench between the three-dimensional driving force and forces at each suspension/chassis linkage were used to characterize the different transmission paths of vibration energy to the chassis. Third, an experimental model of the suspension was constructed to simulate the configuration of the active control system, using the primary (disturbance) FRFs and secondary (control) FRFs also measured on the test bench. This model was used to optimize the configuration of the control actuators and to evaluate the required forces. Finally, a prototype of an active suspension was implemented and measurements were performed in order to assess the performance of the control approach. A 4.6 dB attenuation on transmitted forces was obtained in the 50–250 Hz range.     

On <Emphasis Type="BoldItalic">S</Emphasis>-strong Mori modules

Let A be an integral domain, \(S\subseteq A\) be a multiplicative set and M a w-module as an A-module. In this paper we investigate S-SM-modules. We give an S-version of the result of Wang and McCasland (Commun Algebra 25:1285–1306, 1997) in the case where S is countable. We prove that M is an S-SM-module if and only if every increasing sequence of w-submodules of M is S-stationary if and only if every increasing sequence of S-w-finite w-submodules of M is S-stationary if and only if every increasing sequence of w-finite type submodules of M is S-stationary.     

A model for a textile winding process

This paper solves the problem of determining the efficiency of N machines uni-directionally patrolled by one operative when walking time between the machines is constant, and repair time is constant, but repairs are not always successful. The problem arises in the context of a textile winding process and the results are of value in maintaining controls over the process. The increased efficiency that results from the operative repeatedly trying to repair a stopped machine, rather than leaving it stopped and continuing with his patrol is also calculated, and the design implications of this improved strategy are considered.     

Determination of 1,4-benzodiazepines in drug dosage forms by difference spectrophotometry

A spectrophotometric method has been developed for the determination of seven 1,4-benzodiazepines, namely: chlordiazepoxide, diazepam, nitrazepam, oxazepam, lorazepam, temazepam and cinolazepam. The method involves reduction of the target compounds using Zn/HCl and measuring the difference in the absorbance before and after reduction. The quantities of zinc and acid required for efficient reduction were carefully studied. 1–20 g ml^–1 of the compounds could be determined with < 1% error. The method was applied successfully to the determination of these compounds in pharmaceutical dosage forms. The results were sufficiently accurate and precise and comparable to those from the official methods.     

Kinetic spectrophotometric determination of the macrolide antibiotic josamycin in formulations

A simple kinetic spectrophotometric method was developed for the determination of josamycin in its dosage forms. The method is based on oxidation of the drug with alkaline potassium permanganate at room temperature for a fixed time of 20 min and measuring the produced green color at 611 nm. The absorbance-concentration plot is rectilinear over the range of 2-10 microg/mL (2.4 x 10(6)-1.2 x 10(-5)M) with minimum detectability of 1.0 microg/mL (1.2 x 10(-6)M). The determination of josamycin by fixed concentration and the rate-constant methods is also feasible with the calibration equations obtained, but the fixed-time method proved to be more applicable. The procedure was applied successfully to commercial tablets, and statistical analysis showed that the results compared favorably with those obtained by reference methods. The effect of sensitizers and surfactants on the performance of the proposed method was also studied. A proposal of the reaction pathway was presented.     

Polarographic behaviour and determination of beclomethasone dipropionate

The polarographic behaviour of beclomethasone dipropionate in Britton-Robinson buffers containing 40% methanol as a solubilizer has been studied. Over the pH range 1.8–12, a cathodic wave was produced, which was characterised as being irreversible, diffusion controlled and free from adsorption phenomena. The number of electrons involved in the reduction was found through comparative study with spironolactone. Using direct current polarographic mode, the limiting current concentration plot is rectilinear over the range 2.5 × 10^–5 to 4 × 10^–4 mol/1 with a detection limit of 2.5 × 10^–6 mol/1. A method has been developed for the determination of the drug in aerosols and creams, the results being in agreement with those obtained by the official method.     

Reactivity study on morpholine‐1‐carbothioic acid (2‐phenyl‐3H‐quinazolin‐4‐ylidene) amide

Regioselective reactions of morpholine‐1‐carbothioic acid (2‐phenyl‐3H‐quinazolin‐4‐ylidene) amide ( 1 ) with electrophiles and nucleophiles were studied. The compound ( 1 ) reacts with alkyl halides in basic medium to afford S‐substituted isothiourea derivatives, with amines to give 1,1‐disubstituted‐3‐(2‐phenyl‐3H‐quinazolin‐4‐ylidene) thioureas and l‐substituted‐3‐(2‐phenyl‐quinazolin‐4‐yl) thioureas via transami‐nation reaction. The reaction of ( 1 ) with amines in the presence of H₂O₂ provided N⁴‐disubstituted‐N'⁴‐(2‐phenylquinazolin‐4‐yl)morpholin‐4‐carboximidamide via oxidative desulfurization. Estimation of reactivity sites on ( 1 ) was supported using the ab initio (HF/6‐31G**) quantum chemistry calculations. The ir, ¹H nmr, ¹³C nmr, mass spectroscopy and x‐ray identified the isolated products.     

Spectrophotometric determination of some pharmaceutically-important aminoquinoline antimalarials

A simple and rapid spectrophotometric method for the assay of amodiaquine hydrochloride, chloroquine phosphate and primequine phosphate is described. The method is based on the interaction of the drug with tetracyanoethylene to give a stable charge transfer complex. The spectra of the complex show maxima at 413, 415 and 415nm, respectively, with high apparent molar absorptivities. Beer's law is obeyed in the concentration ranges 2–12, 1–8 and 2–12 g ml^–1 of the three drugs studied. The proposed method is applied to the determination of these drugs in certain formulations and the results are favourably comparable to the official methods.