Study of inaccuracy in semi-analytical sensitivity analysis — a model problem

The semi-analytical method of sensitivity analysis (Zienkiewicz and Campbell 1973; Esping 1983; Cheng and Liu 1987) of finite element discretized structures is attractive due to the balance between computational cost and ease of implementation (Cheng and Liu 1987; Haftka and Adelman 1989), but unfortunately the method may exhibit serious inaccuracies when applied in shape optimization of structures modelled by beam, plate, shell and Hermite elements (Cheng and Liu 1987; Haftka and Adelman 1989; Barthelemyet al. 1988; Barthelemy and Haftka 1988; Choi and Twu 1991, Pedersenet al. 1989; Chenget al. 1989).In the present paper, we perform an exact analysis of the error of sensitivity for a simple model problem which has earlier been considered by Barthelemyet al. (1988), Barthelemy and Haftka (1988), Pedersenet al. (1989). The analysis gives a deep insight into the nature of the general inaccuracy problem and enables us to devise methods by which the severe error of the sensitivity can be substantially reduced or removed for the model problem. The results of the paper are illustrated via an example.A method of error elimination for an extended class of semianalytical analysis problems is developed and presented in a companion paper (Olhoff and Rasmussen 1991).     

Neutron and capture γ-ray accumulation factors in engineering calculations of reactor shielding

Translated from Atomnaya Énergiya, Vol. 66, No. 5, pp. 321–324, May, 1989.     

Angle and energy characteristics of neutrons produced by a high-energy ion beam

Translated from Atomnaya Énergiya, Vol. 66, No. 3, pp. 213–215, March, 1989.     

Effect of shape on the radiation-stimulated deformation of crystals

Translated from Atomnaya Énergiya, Vol. 66, No. 3, pp. 208–209, March, 1989.     

Analog regulators of the energy-liberation distribution in nuclear reactors

Translated from Atomnaya Énergiya, Vol. 66, No. 2, pp. 81–85, February, 1989.     

Estimation of the Equilibrium Constants for Pure Hydrocarbons

Equilibrium constants of pure hydrocarbons in different temperatures and pressures are necessary in most engineering calculations. A general formula has been developed to calculate equilibrium value for a group of hydrocarbons which have the general formula C_n H_2n+2 and C_n H_2n based on three parameters. This formula is a function of reduced temperature, reduced pressure, and an acentric factor. It is applied within a wide range of temperatures and pressures. As a result this technique is considered to be useful for the predication of K values of pure hydrocarbons depending on its reduced temperature, reduced pressure, and acentric factor.     

Fish protection in medium and large open water intakes

A new layout of a fish-protecting facility is proposed. __________ Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 12, December 2006, pp. 24–26.     

Inhibitory activity of ginger rhizome on airway and uterine smooth muscle preparations

In this study, we describe the tracheal-relaxant and tocolytic activities of the methanol (ME) and aqueous (AQ) crude extracts of ginger (rhizome of Zingiber officinale) in an attempt to rationalize its traditional use in disorders of airways and uterine hyperactivity. Both of the ginger extracts dose-dependently relaxed K⁺ (80 mM) and carbachol (CCh, 1 μM)-induced contractions with more potency against K⁺, similar to that elicited by verapamil, a Ca²⁺ channel blocker. In isolated uterine preparations, the extracts suppressed the K⁺-induced contractions with respective EC₅₀ values of 0.03 mg/ml (0.02–0.05, 95% CI) and 0.05 mg/ml (0.04–0.06). Activity-directed fractionation of AQ yielded an organic and an aqueous fraction with the activities concentrated in the former. Both the crude extracts were found safe in mice up to the oral dose of 5 g/kg when tested for acute toxicity for 24 h. The study shows that ginger possesses tracheal and uterine smooth muscle relaxant activity, possibility mediated via Ca²⁺ channel blockade, justifying its use in disorders such as asthma, cough as well as in dysmenorrhoea and uterine and menstrual spasms and congestion.     

The effect of OPWF filler on impact strength of glass-fiber reinforced epoxy composite

In the present study, oil palm wood flour (OPWF) particles with less than 250 μm sizes have been used as filler materials in the woven-glass-fiber reinforced epoxy composite. The hybrid composites were fabricated using a hand lay-up method and cured at room temperature under a compressive load of 196 N (20 kg). The OPWF of 2.5 to 10 parts per hundred (pph) by weight was used to evaluate its effect on impact strength of the hybrid composites at a range of temperature from −50 to 50 °C. The impact strength, evaluated using V-notch Charpy method, showed reduction with increasing filler content up to 5 pph and then the strength increment in those composites containing more than 5 pph OPWF. More severe damages were found in specimens with higher filler contents resulting higher energy absorption during impact. The composites with a large amount of OPWF particles deflected crack propagation paths or created obstacles at the crack tips and increased toughness of the composites. The impact strength was found to decrease when the samples fractured at subzero temperatures and this happened because of the reduction of the matrix ductility at lower temperatures.