8,694 research outputs found
Logistic Supply Chain Management and Economic Security of the Enterprise
Abstract- In recent years, the interdisciplinary research of supply chains and economic security has received extensive, yet gradual, attention; when compared to the rapid economic growth of the service industry, however, sustainable supply chain management has not been systematically explored yet. The security issue in supply chains is among the most pressing concerns that firms are currently facing. So the purpose of this article is to formalize the process of interaction between an enterprise and suppliers of components necessary for the production of products. The process is considered from the point of view of determining the best conditions for the operation of the enterprise under which the production of all planned products is ensured and the costs of the enterprise for the acquisition of components necessary for the production are minimized. The model reflects the unambiguous dependence of purchases on the range and volume of output. Typically, when simulating supply chain processes, the emphasis is on managing the inventory of components of one item on the one hand or on minimizing the cost of shipping only one component. With this approach, the costs of the enterprise as a whole usually fall out of consideration. The proposed economic and mathematical model establishes a close interdependence between the proceeds from the sale of products and the costs of acquiring the components necessary for the production, between the capabilities of suppliers and the needs of the enterprise, in a supply chain model. In this model, emphasis is placed on ensuring the reliability of supplies, their magnitude and timeliness, which should be stipulated in contracts for the supply of necessary components. The model implicitly takes into account the presence of accounts payable, which may affect the amount of funds allocated for the purchase of components necessary for the production. The advantages of the model should also include accounting for the availability of components at the time of procurement. As an additional effect of the application of the model, the possibility of minimizing working capital through the implementation of a sound logistics policy based on existing working capital and their use to ensure timely delivery in the required volumes of components is considered. The supply chain ensures the economic security of the enterprise. The effective use of working capital contributes to an increase in the profitability of the enterprise and, as a result, to an increase in the income of the owner
A study of Traveling Ionospheric Disturbances and Atmospheric Gravity Waves using EISCAT Svalbard Radar IPY-data
We present a statistical study of Traveling Ionospheric
Disturbances (TIDs) as observed by the EISCAT Svalbard Radar (ESR) during the
continuous IPY-run (March 2007–February 2008) with field-aligned
measurements. We have developed a semi-automatic routine for searching and
extracting Atmospheric Gravity Wave (AGW) activity. The collected data shows
that AGW-TID signatures are common in the high-latitude ionosphere especially
in the field-aligned ion velocity data (244 cases of AGW-TID signatures in
daily records), but they can be observed also in electron density (26 cases),
electron temperature (12 cases) and ion temperature (26 cases). During the
IPY campaign (in solar minimum conditions) AGW-TID events appear more
frequently during summer months than during the winter months. It remains
still as a topic for future studies whether the observed seasonal variation
is natural or caused by seasonal variation in the performance of the
observational method that we use (AGW-TID signature may be more pronounced in
a dense ionosphere). In our AGW-TID dataset the distribution of the
oscillation periods has two peaks, one around 0.5–0.7 h and the other
around 1.1–1.3 h. The diurnal occurrence rate has a deep minimum in the
region of magnetic midnight, which might be partly explained by irregular
auroral activity obscuring the TID signatures from our detection routines. As
both the period and horizontal phase speed estimates (as derived from the
classical AGW dispersion relation) show values typical both for large scale
TIDs and mesoscale TIDs it is difficult to distinguish whether the generator
for high-latitude AGW-TIDs resides typically in the troposphere or in the
near-Earth space. The results of our statistical analysis give anyway some
valuable reference information for the future efforts to learn more about the
dominating TID source mechanisms in polar cap conditions, and to improve AGW
simulations
Application of sorption and membrane methods in the process of water purification from diclofenac
The results of experimental investigation in water purification from pharmaceuticals by the example of diclofenac by means of activated carbon adsorption and using nanofilter membranes are presented. High efficiency of application of these processes in water purification is shown
Interaction between superconducting vortices and Bloch wall in ferrite garnet film
Interaction between a Bloch wall in a ferrite-garnet film and a vortex in a
superconductor is analyzed in the London approximation. Equilibrium
distribution of vortices formed around the Bloch wall is calculated. The
results agree quantitatively with magneto-optical experiment where an in-plane
magnetized ferrite-garnet film placed on top of NbSe2 superconductor allows
observation of individual vortices. In particular, our model can reproduce a
counter-intuitive attraction observed between vortices and a Bloch wall having
the opposite polarity. It is explained by magnetic charges appearing due to
discontinuity of the in-plane magnetization across the wall.Comment: 4 pages, 5 figure
Screening properties of Gaussian electrolyte models, with application to dissipative particle dynamics
We investigate the screening properties of Gaussian charge models of
electrolyte solutions by analysing the asymptotic behaviour of the pair
distribution functions. We use a combination of Monte-Carlo simulations with
the hyper-netted chain integral equation closure, and the random phase
approximation, to establish the conditions under which a screening length is
well defined and the extent to which it matches the expected Debye length. For
practical applications, for example in dissipative particle dynamics, we are
able to summarise our results in succinct rules-of-thumb which can be used for
mesoscale modeling of electrolyte solutions. We thereby establish a solid
foundation for future work, such as the systematic incorporation of specific
ion effects.Comment: 9 pages, 9 figures, 1 table, RevTeX4-
Optimization of the Wound Reparation Process
Nowadays, postoperative wound complications are quite frequent in surgery. Various medicines and physical methods are widely used to accelerate reparative regeneration (1,2). So far, the effect of oxygen air ions on the wound healing process has not been studied. Meanwhile, aeroionotherapy, characterized by an anti-oxidant action, can have an inducer effect.The purpose of the research was to study the effect of oxygen air ions on the regeneration of tissue structures of a laparotomic wound. Clinical and laboratory studies were conducted in 48 patients (divided into two groups) with acute peritonitis of appendicular origin. The patients of the basic group underwent aerorionotherapy in the early postoperative period. While using aeroionotherapy, the reparative process was faster and more perfect. The effect of oxygen air ions was accompanied by an acceleration of the inflammatory reaction course, which is manifested by the rapid migration of cellular elements to the wound surface and their differentiation into the connective tissues. This important fact explains the anti-inflammatory effect of such therapy, its capability to inhibit the alterative process and stimulate the reparative process. In the basic group, the intensity of biological consolidation was significantly different from that of the comparison group. Only 3 days after the operation, it was higher than the control value by 23.2%, after 5 days - by 37.7%, after 7 days - by 35.6% (p <0.01). Thus, the obtained data suggest that the negative oxygen air ions should have a rather pronounced regenerative effect
Double bracket dissipation in kinetic theory for particles with anisotropic interactions
We derive equations of motion for the dynamics of anisotropic particles
directly from the dissipative Vlasov kinetic equations, with the dissipation
given by the double bracket approach (Double Bracket Vlasov, or DBV). The
moments of the DBV equation lead to a nonlocal form of Darcy's law for the mass
density. Next, kinetic equations for particles with anisotropic interaction are
considered and also cast into the DBV form. The moment dynamics for these
double bracket kinetic equations is expressed as Lie-Darcy continuum equations
for densities of mass and orientation. We also show how to obtain a
Smoluchowski model from a cold plasma-like moment closure of DBV. Thus, the
double bracket kinetic framework serves as a unifying method for deriving
different types of dynamics, from density--orientation to Smoluchowski
equations. Extensions for more general physical systems are also discussed.Comment: 19 pages; no figures. Submitted to Proc. Roy. Soc.
Modelling of the Supply Chain Planning for the Business and Economic Security
Abstract— Strategic supply-chain planning that combines aspects of business-strategy formulation with aspects of tactical supply-chain planning can make each far more valuable to the planning effort than either would be alone. The purpose of this article is to assess the economic security of the enterprise in terms of the efficiency of the use of supply chain planning, taking into account the possibility of production and sale of manufactured products. In case of falling demand for products, there are free capacities in the enterprise, which are useful to use to organize the production of additional items. Underutilization of the enterprise leads to higher costs, lower profitability and lower revenues, thus reducing the interest of the owners in the enterprise and thus threatening its existence. The article proposes a system of mathematical models, which allows to effectively use the capacity of the enterprise to increase its profitability due to the self-contained production of additional nomenclature, due to the use of temporarily increasing capacity. As the main hypothesis in the construction of the model, it is assumed that the economic security of the enterprise is determined by the degree of satisfaction of the economic interests of persons interested in the results of its activities. Therefore, it is proposed to consider the economic security of the enterprise from the point of view of effective use of the assets of the enterprise, which creates prerequisites for timely and full fulfilment of mutual obligations by the enterprise on the one hand, and by the owner, personnel, clients, partners, the State on the other. The proposed system of mathematical models implies that the enterprise is oriented towards the production of mass products, the realization of which involves a certain risk. The model assumes that the enterprise produces several types of industrial nomenclature and has the possibility to organize the production of additional nomenclature using available free capacities. The proposed model is intended to assess the feasibility of production, determine the best value for money and thereby increase the profitability of the enterprise. The use of a system of models improves the current activities of the enterprise, the feasibility and effectiveness of the existing innovation policy for the renewal of the production programme. The article provides recommendations for practical use of the model.
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