Dynamical Behavior of a stochastic SIRS epidemic model

In this paper we study the Kernack - MacKendrick model under telegraph noise. The telegraph noise switches at random between two SIRS models. We give out conditions for the persistence of the disease and the stability of a disease free equilibrium. We show that the asymptotic behavior highly depends on the value of a threshold $\lambda$ which is calculated from the intensities of switching between environmental states, the total size of the population as well as the parameters of both SIRS systems. According to the value of $\lambda$, the system can globally tend towards an endemic case or a disease free case. The aim of this work is also to describe completely the omega-limit set of all positive solutions to the model. Moreover, the attraction of the omega-limit set and the stationary distribution of solutions will be pointed out.Comment: 16 page

A Study of Silica Separation in the Production of Activated Carbon from Rice Husk in Viet Nam

Environmental pollution due to mismanagement of the waste from rice production is a serious problem in agricultural countries where rice cultivation occupies the largest proportion of the crops produced, including in Viet Nam. At the same time the use of activated carbon as an adsorption agent for water or gas purification is rapidly increasing due to the development of industry and technology in the developed countries. In this paper we consider the process of separating silica from charcoal, which is an important step in the production of activated carbon from rice husks in Viet Nam. The efficiency of the process rises with increasing temperature up to 133 °С, the ratio of alkali/charcoal up to 0.6 and sodium hydroxide concentration up to 6 M as well. A regression equation has been obtained, which allows describing the influence of the parameters on the degree of silica separation from the carbon. Under optimal values of process parameters, the efficiency reaches up to 95.6%

Production of activated carbon from rice husk Vietnam

This work is dedicated to the production of activated carbon from rice husk from Delta of the Red River in Viet Nam. At the first stage, carbonization of a rice husk was carried out to obtain material containing 43.1% carbon and 25 % silica with a specific surface area of 51.5 m{2}/g. After separating of silica (the second stage), the specific surface area of the product increased to 204 m{2}/g and the silica content decreased to 1.23% by weight as well. The most important stage in the formation of the porous structure of the material is the activation. The products with the high specific surface area in the range of 800-1345 m{2}/g were obtained by activation of carbonized product with water vapour or carbon dioxide at temperatures of 700 °C and 850 °C, with varying the flow rate of the activating agent and activation time. The best results were achieved by activation of carbon material with water vapour at the flow rate of 0.08 dm{3}/min per 500 g of material and the temperature of 850 °C

Innovative design technology: An optimal surgical aid system for Hip Resurfacing Arthroplasty

Hip Resurfacing Arthroplasty (HRA) is a treatment option for the patients with the advanced hip disease; it is considered as the most technically difficult techniques of all procedures recommended for osteonecrosis of the hip. Technically, the currently applied HRA surgeries lead to unstable and inconsistent results. Surgeons rely a lot on the manual technique and conventional tools as well as their skills to determine the right drilling angle for locating the implant system. Although the robotic and surgical planning systems are available for HRA, the drilling line is still defined geometrically and intra-operatively, not fully considering about the biomechanics aspects of the implant and bone structure. In this paper, an optimal surgical aid system for HRA is proposed. With the integration of the state of the art biomedical modelling, pre-operative planning and personalised surgical tools, knowledge based and expert system, as well as biomechanics modelling and analysis, the precision, safety and speed of surgery are improved, the complexity of surgery is reduced, and therefore the survival rate of the implant is increased. Especially, the proposed system provides a cheap and practically feasible solution with the integration of expertise from both engineering and medicine for improving the treatment quality of the patients

Magnetically operated nanorelay based on two single-walled carbon nanotubes filled with endofullerenes Fe@C20

Structural and energy characteristics of the smallest magnetic endofullerene Fe@C20 have been calculated using the density functional theory approach. The ground state of Fe@C20 is found to be a septet state, and the magnetic moment of Fe@C20 is estimated to be 8 Bohr magnetons. Characteristics of an (8,8) carbon nanotube with a single Fe@C20 inside are studied in the framework of the semiempirical approach. The scheme of a magnetic nanorelay based on cantilevered nanotubes filled with magnetic endofullerenes is elaborated. The proposed nanorelay is turned on as a result of bending of nanotubes by a magnetic force. Operational characteristics of such a nanorelay based on (8,8) and (21,21) nanotubes fully filled with Fe@C20 are estimated and compared to the ones of a nanorelay made of a (21,21) nanotube fully filled with experimentally observed (Ho3N)@C80 with the magnetic moment of 21 Bohr magnetons. Room temperature operation of (21,21) nanotube based nanorelays is shown.Comment: 18 pages, 9 figure