This paper investigates joint user association, sub-channel assignment, and power ALLOCATION in the uplink of multi-user orthogonal frequency division multiple access (OFDMA) of a heterogeneous network (HetNet) where users are subject to maximum transmission power constraints. It is shown that the underlying problem is a highly non-convex mixed integer non-linear problem. To tackle the problem, the integer variables are relaxed and a penalty function is added to the objective function to make sure that the relaxed variables take binary values. Finally, the objective function is rewritten as the difference of two convex (D. C. ) functions and the resulting problem is addressed through using the successive convex approximation method. It is worth mentioning that, to the best of the author’ s knowledge, the problem of joint user association, sub-channel ALLOCATION, and power control in the uplink of a heterogeneous network has not been addressed in the literature till now. Simulation results demonstrate the superiority of the proposed method over existing works in terms of achieving higher throughput despite exhibiting a higher complexity.

Development projects in natural water resources like rivers and lakes, specially transferring water to use in agriculture, domestic and industrial sector without considering environmental values, causes irrecoverable and irreversible damage to ecosystem and future options. If we consider the future generation and species rights, those damages and costs can be very much than we take in.The above problem has shown its results in the development projects in Urmia Lake basin in north-western Iran. In our case study, water of Zarinerood is transferred to use in domestic and agriculture sector that made a lot of irrecoverable damage to the ecosystem. In this paper, we develop an optimal control model for allocating a natural water resource by considering irreversibility. The model shows that allocating of basin’s water for different uses is not an optimal policy. Indeed, it intensifies the environmental irreversibility in that ecosystem.

The present study is an attempt towards remodeling cost, revenue and profit relationship within the network process. The previous models of Data Envelopment Analysis (DEA) have been too general in their scope and focused on the input and the output within a black box system, therefore they have not been able to measure various phases simultaneously within a network system. By using these models internal linking activities are neglected. A slacks-based network DEA model is dealt with intermediate products (Tone, Tsutsui). In this development, each input and output can use situations where unit price and unit cost information are available. In this paper we introduce models of cost, revenue and profit efficiency in network DEA. These models are illustrated by numerical examples and finally results of Constant Returns to Scale (CRS) are obtained. The findings could be used in minimizing the costs and maximizing the benefits in various organizations, public services, factories, and public and private sector companies.

In DEA to obtain an efficient representation in CCR and BCC models for each DMU only one linear plan would be solved; however, it is possible in centralized resource ALLOCATION (CRA) to solve all the DMUs by one linear planning. In this paper, models of centralized resource ALLOCATION in input-oriented and in dynamic case will be offered and by using dynamic SBM, the representation of DMUs in each time period and in general and based on CRA in input oriented case will be obtained. After that, the theorems of the offered models will be shown and at least, an applicable example will be represented.