An integrated stochastic model and algorithm for multi-product newsvendor problems

In this paper, a multi-product newsvendor problem is formulated as a random nonlinear integrated optimization model by taking into consideration the selling price, the producing and outsourcing quantities, and the nonlinear budget constraint. Different from the existing models, the demands of products depend on the prices, as well as being time-varying due to random market fluctuation. In addition, outsourcing strategy is adopted to deal with possible shortage caused by the limited capacity. Consequently, the constructed model is involved with joint optimization of the producing and outsourcing quantities, and the selling prices of all the products. For this model with continuous random demands, we first transform it into a nonlinear programming problem by expectation method. Then, an efficient algorithm, called the feasible-direction-based spectral conjugate gradient algorithm, is developed to find a robust solution of the model. By case study and sensitivity analysis, some interesting conclusions are drawn as follows: (a) Budget is a critical constraint for optimizing the decision-making of the retailer, and there exist different threshold values of the budget for the substitute and complementarity scenarios. (b) The price sensitivity matrix seriously affects the maximal expected profit mainly through affecting the optimal outsourcing quantity.

Uplink NOMA in Body Area Networks With Simple Node Pairing Strategies

In body area networks (BANs), a node placed near the hub has a significant signal strength advantage. This issue, known as near-far problem, indicates that a near node may serve as a relay for a far node. Currently, the established orthogonal multiple access (OMA) requires the allocation of a specific resource block to a single node. In contrast, the emerging non-orthogonal multiple access (NOMA) allows simultaneous transmissions and uses successive interference cancellation (SIC) to recover the signals. For the first time in the literature, we introduce NOMA in BANs, to allow simultaneous transmissions from two nodes at a time, with distinguishable power levels. The crucial part of this technique is the dynamic pairing of the nodes by the hub. First, we review the fundamentals of uplink NOMA and we propose an access protocol in compliance with IEEE 802.15.6-2012, which combines random OMA with scheduled NOMA. Next, we propose three node pairing strategies, namely a random, a correlative and a conditional one, to meet the requirements of several applications. These strategies are evaluated with packet level simulations in OMNeT++. Our results show that the proposed scheme outperforms the basic OMA scheme at high packet rates and provides a feasible direction for novel relay-based applications.

Uplink NOMA in Body Area Networks With Simple Node Pairing Strategies

In body area networks (BANs), a node placed near the hub has a significant signal strength advantage. This issue, known as near-far problem, indicates that a near node may serve as a relay for a far node. Currently, the established orthogonal multiple access (OMA) requires the allocation of a specific resource block to a single node. In contrast, the emerging non-orthogonal multiple access (NOMA) allows simultaneous transmissions and uses successive interference cancellation (SIC) to recover the signals. For the first time in the literature, we introduce NOMA in BANs, to allow simultaneous transmissions from two nodes at a time, with distinguishable power levels. The crucial part of this technique is the dynamic pairing of the nodes by the hub. First, we review the fundamentals of uplink NOMA and we propose an access protocol in compliance with IEEE 802.15.6-2012, which combines random OMA with scheduled NOMA. Next, we propose three node pairing strategies, namely a random, a correlative and a conditional one, to meet the requirements of several applications. These strategies are evaluated with packet level simulations in OMNeT++. Our results show that the proposed scheme outperforms the basic OMA scheme at high packet rates and provides a feasible direction for novel relay-based applications.

A new non-monotonic infeasible simplex-type algorithm for Linear Programming

This paper presents a new simplex-type algorithm for Linear Programming with the following two main characteristics: (i) the algorithm computes basic solutions which are neither primal or dual feasible, nor monotonically improving and (ii) the sequence of these basic solutions is connected with a sequence of monotonically improving interior points to construct a feasible direction at each iteration. We compare the proposed algorithm with the state-of-the-art commercial CPLEX and Gurobi Primal-Simplex optimizers on a collection of 93 well known benchmarks. The results are promising, showing that the new algorithm competes versus the state-of-the-art solvers in the total number of iterations required to converge.

Creation of centre for implementation of innovation projects as economic and pedagogic tool in educational holding structure

This article discloses feasible direction for improvement of training students at the structure of educational holding based on such economic and pedagogical tool as centre for implementation of innovation projects. It is substantiated that design and implementation of the modern IT-focused innovation and investment projects contribute development for professional competencies of students. And it also allows reaching better connection and correlation between theory and praxis. It is suggested basic for creation of mentioned centre according to nowadays realities.