Delay-dependent criterion for exponential stability analysis of neural networks with time-varying delays

This note investigates the problem of exponential stability of neural networks with time-varying delays. To derive a less conservative stability condition, a novel augmented Lyapunov-Krasovskii functional (LKF) which includes triple and quadruple-integral terms is employed. In order to reduce the complexity of the stability test, the convex combination method is utilized to derive an improved delay dependent stability criterion in the form of linear matrix inequalities (LMIs). The superiority of the proposed approach is demonstrated by two comparative examples

Household knowledge and practices concerning malaria and indoor residual spraying in an endemic area earmarked for malaria elimination in Iran

Abstract Background Indoor residual spraying of insecticide (IRS) is a key intervention for reducing the burden of malaria infection. Effectiveness and success of this strategy are to a considerable extent dependent on knowledge and practice of the target community regarding the IRS. Iran has entered the malaria elimination phase, and IRS has been considered as the main strategy for malaria vector control. Therefore, this study was conducted to determine the household knowledge and practices about malaria and IRS in Bashagard County, one of the malaria-endemic areas in the southeast of Iran. Methods A community-based cross-sectional survey was conducted among 420 households in Bashagard County. The participants who were selected using a two-stage randomized cluster sampling procedure were subjected to a tested structured questionnaire. During the survey, direct observations were made concerning the use of IRS as well as housing conditions. The data were coded and analysed using SPSS version 19. Results Knowledge levels about malaria as a disease and the mosquito as its vector were high and of equal magnitude (85.5% and 85.4%, respectively), while knowledge levels of IRS were even higher (91.6%). The main source of households’ information about malaria and IRS was primarily community health workers (73.3%). Despite positive perceptions towards IRS only 26.7% of respondents had sprayed their houses which is lower than the WHO targeted coverage of 80%. Respiratory disorders and headache (33.3%), food contamination (24.9%), discolouring of inner house walls (17.7%), difficulty in furniture’s movement (13.8%), and unpleasant odour (10.4%) were the main reasons for IRS refusal. Conclusion There is a discrepancy between knowledge about symptoms and the transmission route of malaria and control practices related to IRS use. Therefore, IRS campaigns accompanied with education for behaviour change should be considered to ensure householders’ participation and cooperation in the IRS programme. Moreover, continuous evaluation and monitoring of IRS as well as conducting more surveys on knowledge, attitude, and practices are recommended to improve malaria control measures and to identify indicators for effective, successful, and sustainable malaria elimination programme

An insight into a di-chain surfactant adsorption onto sandstone minerals under different salinity-temperature conditions: Chemical EOR applications

Surfactant flooding, a chemical enhanced oil recovery (EOR) technique, mainly aims at mobilizing the trapped residual oil by lowering the oil-water interfacial tension. The success of a surfactant flooding operation is strongly affected by surfactant loss through its adsorption on reservoir minerals. Therefore, the adsorption behavior of surfactants is of great importance and needs to be carefully investigated. The present study provides an insight into the adsorption behavior of a recently proposed surfactant, namely Aerosol-OT, on a number of minerals — including quartz-sand, kaolinite, illite, and montmorillonite — under different salinities and temperatures. The examination was carried out in the form of batch experiments, and the surface tension technique was implemented to determine the adsorption rate. The adsorption equilibrium data were examined through two adsorption isotherm models known as Langmuir and Freundlich. It was found that the adsorption rate increased with the increasing salinity, where the highest value was observed for kaolinite (21 g/kg). However, an opposite trend occurred for temperature with the lowest adsorption rate (1.68 g/kg) was obtained for quartz-sand at 85 °C. The adsorption rate of Aerosol-OT was found to be higher than the conventional surfactants. A good correlation was seen between the equilibrium adsorption data and Langmuir isotherm model as their correlation coefficient () exceeded 0.999. The results provide a useful tool to screen surfactants for the chemical EOR operation in clay-rich reservoirs