Search results for " programmi"
showing 10 items of 1629 documents
Comparative evaluation of some interactive reference point-based methods for multi-objective optimisation
1999
Many real-world optimisation applications include several conflicting objectives of possibly nondifferentiable character. However, the lack of computationally efficient, interactive methods for nondifferentiable multi-objective optimisation problems is apparent. To satisfy this demand, a method called NIMBUS has been developed. Two versions of the basic method are presented and compared both theoretically and computationally. In order to give variety to the comparison, a related approach, called reference direction method is included. Theoretically, the methods differ in handling the information requested from the user. Numerical experiments indicate differences in computational efficiency …
Customers' purchase intentions as a reflection of price perception
2008
Purpose – The purpose of this paper is to investigate customers' intentions to purchase mobile communications services and how these intentions are affected by the customers' price perceptions in two customer segments – a mobile segment and a combined segment. A further aim was to gain insight into the formation of price perceptions, and customer characteristics that underlie the differences between purchase intentions and price perceptions.Design/methodology/approach – The study was conducted in the Finnish mobile services market. The sample data were collected through a postal survey (n=3,000) sent to customers of a Finnish teleoperator. In analyzing empirical data the explanatory factor …
Improving demand forecasting accuracy using nonlinear programming software
2006
We address the problem of forecasting real time series with a proportion of zero values and a great variability among the nonzero values. In order to calculate forecasts for a time series, the model coefficients must be estimated. The appropriate choice of values for the smoothing parameters in exponential smoothing methods relies on the minimization of the fitting errors of historical data. We adapt the generalized Holt–Winters formulation so that it can consider the starting values of the local components of level, trend and seasonality as decision variables of the nonlinear programming problem associated with this forecasting procedure. A spreadsheet model is used to solve the problems o…
Aggregation methods to calculate the average price
2015
Abstract Average price is a numerical value that represents a set of prices, which may relate to firms, countries, or regions. This study presents new methods of average price aggregation that build on the unified aggregation operator (UAO). The UAO combines a wide range of sub-aggregation processes into a single formulation capable of accounting for the importance of each concept in the analysis. The aggregation system is flexible, can adapt to different environments, and provides a complete representation of relevant information. The UAO can calculate the average price for numerous geographical contexts such as supranational regions and countries. The study illustrates the UAO's utility b…
Aggregation systems for sales forecasting
2015
Abstract Sales forecasting consists of calculating the expected sales of a specific product or company. An important issue when dealing with sales forecasting is the calculation of the average sales, usually using the arithmetic mean or the weighted average. This study introduces new methods for calculating the average sales. These methods are two modern aggregation operators: the ordered weighted average, and the unified aggregation operator. The main advantage of this approach is the possibility to deal with uncertain and complex environments in a more complete way. The study develops some key examples through multi-person and multi-criteria techniques. The study also presents a numerical…
Why do retail consumers buy green apparel? A knowledge-attitude-behaviour-context perspective
2021
Consumers' increased knowledge and awareness of environmental issues have not translated into a pervasive rise in purchasing green apparel, resulting in a phenomenon known as the ‘attitude-behaviour gap’. The current study seeks to explicate this gap by examining the drivers of green apparel buying behaviour. Towards this end, the study examines the association of environmental knowledge, green trust, and environmental concern with environmental attitude and green apparel buying behaviour. It further investigates the association of labelling desire and labelling satisfaction with this type of buying behaviour as well. In addition, the study uses the theoretical lens of the knowledge-attitud…
A Single radio based channel datarate-aware parallel rendezvous MAC protocol for cognitive radio networks
2009
Channel hopping based parallel rendezvous multichannel MAC protocols have several advantages since they do not need a control channel, require only one transceiver, and produce higher system capacity. However, channel hopping sequences in existing parallel rendezvous MAC protocols have been designed as irrelevant to channel datarates, leading to under-utilization of channel resources in multi-rate multi-channel networks. Considering that datarates among channels may be different, we propose a dynamic parallel rendezvous multichannel MAC protocol for synchronized cognitive radio networks in which the secondary users adjust their own distinct hopping sequences according to the datarates of th…
Stationary and non-stationary stochastic response of linear fractional viscoelastic systems
2012
Abstract A method is presented to compute the stochastic response of single-degree-of-freedom (SDOF) structural systems with fractional derivative damping, subjected to stationary and non-stationary inputs. Based on a few manipulations involving an appropriate change of variable and a discretization of the fractional derivative operator, the equation of motion is reverted to a set of coupled linear equations involving additional degrees of freedom, the number of which depends on the discretization of the fractional derivative operator. As a result of the proposed variable transformation and discretization, the stochastic analysis becomes very straightforward and simple since, based on stand…
Collision Avoidance in Wake-Up Radio Enabled WSNs: Protocol and Performance Evaluation
2018
In wake-up radio (WuR) enabled wireless sensor networks (WSNs), the envisaged application scenarios are primarily targeted at low traffic load conditions. When applying WuR to medium or heavy traffic load scenarios, however, collisions among wake-up calls (WuCs) may happen, resulting in a lower packet delivery ratio (PDR). In this paper, we propose a media access control protocol for WuR- enabled WSN that is capable of avoiding WuC collisions by activating a contention-based collision avoidance mechanism for WuC transmissions. The performance of the proposed protocol is evaluated by a Markov chain based mathematical model and is compared with a WuR protocol that performs only clear channel as…
Real Time Stereo Matching Using Two Step Zero-Mean SAD and Dynamic Programing
2018
Dense depth map extraction is a dynamic research field in a computer vision that tries to recover three-dimensional information from a stereo image pair. A large variety of algorithms has been developed. The local methods based on block matching that are prevalent due to the linear computational complexity and easy implementation. This local cost is used on global methods as graph cut and dynamic programming in order to reduce sensitivity to local to occlusion and uniform texture. This paper proposes a new method for matching images based on a two-stage of block matching as local cost function and dynamic programming as energy optimization approach. In our work introduce the two stage of th…