Specific activator and repressor transcription factors which bind to specific regulator DNA seque... more Specific activator and repressor transcription factors which bind to specific regulator DNA sequences, play an important role in gene activity control. Interactions between genes coding such transcripion factors should explain the different stable or sometimes oscillatory gene activities characteristic for different tissues. In this paper, the dynamic P53-Mdm2 interaction model with distributed delays and weak kernel, is investigated. Choosing the
For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maxima... more For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maximal set possible. In this paper we are focused on presenting an algorithm with which the user can obtain any subsets of aggregations types from the maximal set. Our algorithm supposes that, before inserting records in tables, we know the desired aggregation types. We present our algorithm for a snowflake scheme, using a fact table and some dimension tables. Our algorithm can be easily extended to a constellation scheme.
In this paper, we analyze a technology diffusion model with distributed time delays. In the proce... more In this paper, we analyze a technology diffusion model with distributed time delays. In the process of adoption a technology, a firm takes into account the advertising effectiveness, government policy and production costs. The average time for making the final decision is introduced. The mathematical model is described by a system with three nonlinear differential equations with distributed time delays. Two types of kernels are taken into account: Dirac and weak. When the distributions are Dirac, the cases, with one delay and two different delays, are considered. The conditions for the existence of a Hopf bifurcation are given. The stochastic and fractional technology diffusion models are introduced and their orbits are displayed. The last part of the paper includes numerical simulations and conclusions.
Abstract:- In many economic analyses, situations occur when we need to obtain aggregated values. ... more Abstract:- In many economic analyses, situations occur when we need to obtain aggregated values. For n fields (used for grouping) from a database, we can obtain 2 n aggregation types- the maximal set possible. For economic reasons, some from these aggregation types are important, other, probably are not. In this paper we are focused on presenting algorithms with which the user can obtain any subsets of aggregation types from the maximal set. The selection of aggregation types is made according to the economic problem. Key-Words: aggregated value sets, economic analyses, relational databases, programming environment 1
For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maxima... more For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maximal set possible (obtained, for example, with the Cube operator from Oracle). In this paper we want to present one algorithm with which the user can obtain any subsets from this maximal set.
Guardian of the genome, p53 gene, and its partners that form the complex network involved in apop... more Guardian of the genome, p53 gene, and its partners that form the complex network involved in apoptosis and cell cycle arrest, is put under investigation. Some relevant mathematical models are described and each of them contains variables with time delay. For given values of the models parameters, numerical simulations and conclusions are made.
Economic Computation and Economic Cybernetics Studies and Research, 2016
In the present paper, we study two nonlinear systems which describe the price dynamics of a singl... more In the present paper, we study two nonlinear systems which describe the price dynamics of a single commodity market. The market price is expressed with the demand and supply functions for the commodity. The distributed time delay is introduced in the demand and supply prices. It is assumed that the consumer and producer behavior depends on the weighted function of the past prices. The demand can take into account the recent price and the past demand price. The producer can consider the past supply price. Thus, we obtain two nonlinear mathematical models for the price dynamics. In some conditions, there is only one positive equilibrium point. The stability of the equilibrium point and the existence of periodic solutions are investigated. We find the conditions so that the equilibrium point is locally asymptotically stable. The numerical simulations illustrate the effectiveness of our results and some conclusions and future research are provided.
In the present paper we study some models for the price dynamics of a single commodity market. Th... more In the present paper we study some models for the price dynamics of a single commodity market. The quantities of supplied and demanded are regarded as a function of time. Nonlinearities in both supply and demand functions are considered. The inventory and the level of inventory are taken into consideration. Due to the fact that the consumer behavior affects commodity demand, and the behavior is influenced not only by the instantaneous price, but also by the weighted past prices, the distributed time delay is introduced. The following kernels are taken into consideration: demand price weak kernel and demand price Dirac kernel. Only one positive equilibrium point is found and its stability analysis is presented. When the demand price kernel is weak, under some conditions of the parameters, the equilibrium point is locally asymptotically stable. When the demand price kernel is Dirac, the existence of the local oscillations is investigated. A change in local stability of the equilibrium...
Abstract In this paper, an Internet model with one route, one resource, and a nonadaptive user an... more Abstract In this paper, an Internet model with one route, one resource, and a nonadaptive user and round-trip continuous distributed delay has been studied. We have shown that a Hopf bifurcation occurs in such a model, yielding a family of periodic orbits bifurcating out from the network ...
We consider the model of interaction between the immune system and tumor cells including a memory... more We consider the model of interaction between the immune system and tumor cells including a memory function that reflect the influence of the past states, to simulate the time needed by the latter to develop a chemical and cell mediated response to the presence of the tumor. The memory function is called delay kernel. The results are compared with those from other papers, concluding that the memory function introduces new instabilities in the system leading to an uncontrolable growth of the tumor. If the coefficient of the memory function is used as a bifurcation parameter, it is found that Hopf bifurcation occurs for kernel. The direction and stability of the bifurcating periodic solutions are determined. Some numerical simulations for justifying the theoretical analysis are also given.
In this paper, we consider Internet models, which respond to a congestion signal from the network... more In this paper, we consider Internet models, which respond to a congestion signal from the network described by a stochastic and hybrid differential equation. We consider Internet networks with one source and r access links, as well as with r sources and one access link. We analyze the conditions for the existence of a solution and the algorithms needed to determine the solution. We carry out numerical simulations for certain parameter values.
In this paper, we study the heterogeneous duopoly with product differentiation, in which one firm... more In this paper, we study the heterogeneous duopoly with product differentiation, in which one firm is quantity setter and the other is price setter. The deterministic and stochastic models with delay are presented and fuzzy and hybrid models, as well. For the stochastic disturbance model with delay, sufficient conditions are done so that the steady state is asymptotically stable in mean and in mean square. Using programs in Maple 13 we make some numerical simulations that verify the theoretical results.
In this paper, we consider Internet models, which respond to a congestion signal from the network... more In this paper, we consider Internet models, which respond to a congestion signal from the network described by a stochastic differential equation. We consider Internet networks with one source and n access links, as well as with r sources and one access link. We analyze the conditions for the existence of a solution and the algorithms needed to determine the solution. We carry out numerical simulations for certain parameter values.
This paper presents the Kaldor-Kalecki nonlinear business cycle model of the income. It will take... more This paper presents the Kaldor-Kalecki nonlinear business cycle model of the income. It will take into consideration the investment demand in the form suggested by Rodano. We will analyze the deterministic, uncertainty and stochastic Kaldor-Kalecki models. The dynamics of the mean values and the square mean values of the model's variables are set. Numerical examples are given in the end, to illustrate our theoretical results.
Specific activator and repressor transcription factors which bind to specific regulator DNA seque... more Specific activator and repressor transcription factors which bind to specific regulator DNA sequences, play an important role in gene activity control. Interactions between genes coding such transcripion factors should explain the different stable or sometimes oscillatory gene activities characteristic for different tissues. In this paper, the dynamic P53-Mdm2 interaction model with distributed delays and weak kernel, is investigated. Choosing the
For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maxima... more For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maximal set possible. In this paper we are focused on presenting an algorithm with which the user can obtain any subsets of aggregations types from the maximal set. Our algorithm supposes that, before inserting records in tables, we know the desired aggregation types. We present our algorithm for a snowflake scheme, using a fact table and some dimension tables. Our algorithm can be easily extended to a constellation scheme.
In this paper, we analyze a technology diffusion model with distributed time delays. In the proce... more In this paper, we analyze a technology diffusion model with distributed time delays. In the process of adoption a technology, a firm takes into account the advertising effectiveness, government policy and production costs. The average time for making the final decision is introduced. The mathematical model is described by a system with three nonlinear differential equations with distributed time delays. Two types of kernels are taken into account: Dirac and weak. When the distributions are Dirac, the cases, with one delay and two different delays, are considered. The conditions for the existence of a Hopf bifurcation are given. The stochastic and fractional technology diffusion models are introduced and their orbits are displayed. The last part of the paper includes numerical simulations and conclusions.
Abstract:- In many economic analyses, situations occur when we need to obtain aggregated values. ... more Abstract:- In many economic analyses, situations occur when we need to obtain aggregated values. For n fields (used for grouping) from a database, we can obtain 2 n aggregation types- the maximal set possible. For economic reasons, some from these aggregation types are important, other, probably are not. In this paper we are focused on presenting algorithms with which the user can obtain any subsets of aggregation types from the maximal set. The selection of aggregation types is made according to the economic problem. Key-Words: aggregated value sets, economic analyses, relational databases, programming environment 1
For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maxima... more For n fields (used for grouping) from a database, we can obtain 2n aggregation types - the maximal set possible (obtained, for example, with the Cube operator from Oracle). In this paper we want to present one algorithm with which the user can obtain any subsets from this maximal set.
Guardian of the genome, p53 gene, and its partners that form the complex network involved in apop... more Guardian of the genome, p53 gene, and its partners that form the complex network involved in apoptosis and cell cycle arrest, is put under investigation. Some relevant mathematical models are described and each of them contains variables with time delay. For given values of the models parameters, numerical simulations and conclusions are made.
Economic Computation and Economic Cybernetics Studies and Research, 2016
In the present paper, we study two nonlinear systems which describe the price dynamics of a singl... more In the present paper, we study two nonlinear systems which describe the price dynamics of a single commodity market. The market price is expressed with the demand and supply functions for the commodity. The distributed time delay is introduced in the demand and supply prices. It is assumed that the consumer and producer behavior depends on the weighted function of the past prices. The demand can take into account the recent price and the past demand price. The producer can consider the past supply price. Thus, we obtain two nonlinear mathematical models for the price dynamics. In some conditions, there is only one positive equilibrium point. The stability of the equilibrium point and the existence of periodic solutions are investigated. We find the conditions so that the equilibrium point is locally asymptotically stable. The numerical simulations illustrate the effectiveness of our results and some conclusions and future research are provided.
In the present paper we study some models for the price dynamics of a single commodity market. Th... more In the present paper we study some models for the price dynamics of a single commodity market. The quantities of supplied and demanded are regarded as a function of time. Nonlinearities in both supply and demand functions are considered. The inventory and the level of inventory are taken into consideration. Due to the fact that the consumer behavior affects commodity demand, and the behavior is influenced not only by the instantaneous price, but also by the weighted past prices, the distributed time delay is introduced. The following kernels are taken into consideration: demand price weak kernel and demand price Dirac kernel. Only one positive equilibrium point is found and its stability analysis is presented. When the demand price kernel is weak, under some conditions of the parameters, the equilibrium point is locally asymptotically stable. When the demand price kernel is Dirac, the existence of the local oscillations is investigated. A change in local stability of the equilibrium...
Abstract In this paper, an Internet model with one route, one resource, and a nonadaptive user an... more Abstract In this paper, an Internet model with one route, one resource, and a nonadaptive user and round-trip continuous distributed delay has been studied. We have shown that a Hopf bifurcation occurs in such a model, yielding a family of periodic orbits bifurcating out from the network ...
We consider the model of interaction between the immune system and tumor cells including a memory... more We consider the model of interaction between the immune system and tumor cells including a memory function that reflect the influence of the past states, to simulate the time needed by the latter to develop a chemical and cell mediated response to the presence of the tumor. The memory function is called delay kernel. The results are compared with those from other papers, concluding that the memory function introduces new instabilities in the system leading to an uncontrolable growth of the tumor. If the coefficient of the memory function is used as a bifurcation parameter, it is found that Hopf bifurcation occurs for kernel. The direction and stability of the bifurcating periodic solutions are determined. Some numerical simulations for justifying the theoretical analysis are also given.
In this paper, we consider Internet models, which respond to a congestion signal from the network... more In this paper, we consider Internet models, which respond to a congestion signal from the network described by a stochastic and hybrid differential equation. We consider Internet networks with one source and r access links, as well as with r sources and one access link. We analyze the conditions for the existence of a solution and the algorithms needed to determine the solution. We carry out numerical simulations for certain parameter values.
In this paper, we study the heterogeneous duopoly with product differentiation, in which one firm... more In this paper, we study the heterogeneous duopoly with product differentiation, in which one firm is quantity setter and the other is price setter. The deterministic and stochastic models with delay are presented and fuzzy and hybrid models, as well. For the stochastic disturbance model with delay, sufficient conditions are done so that the steady state is asymptotically stable in mean and in mean square. Using programs in Maple 13 we make some numerical simulations that verify the theoretical results.
In this paper, we consider Internet models, which respond to a congestion signal from the network... more In this paper, we consider Internet models, which respond to a congestion signal from the network described by a stochastic differential equation. We consider Internet networks with one source and n access links, as well as with r sources and one access link. We analyze the conditions for the existence of a solution and the algorithms needed to determine the solution. We carry out numerical simulations for certain parameter values.
This paper presents the Kaldor-Kalecki nonlinear business cycle model of the income. It will take... more This paper presents the Kaldor-Kalecki nonlinear business cycle model of the income. It will take into consideration the investment demand in the form suggested by Rodano. We will analyze the deterministic, uncertainty and stochastic Kaldor-Kalecki models. The dynamics of the mean values and the square mean values of the model's variables are set. Numerical examples are given in the end, to illustrate our theoretical results.
Uploads