Factors related to the rejection and/or abandonment of AAC devices

More than 3.5 million Americans have such significant communication disability that they cannot rely on their natural speech to meet their communication needs. As a result, these individuals are severely restricted in their participation in all aspects of life, including their education, employment, family, and community. Augmentative and alternative communication strategies offer great potential to enhance the communication of individuals with complex communication needs, and therefore improve their quality of life. Fifty-two ISAAC members that responded to the online survey utilized a 5 point Likert-type scale (strongly agree to strongly disagree) to rate the importance of factors as they relate to the rejection and/or abandonment. The mean values of ratings were calculated to determine which factors were cited as relevant in predicting AAC device rejection and abandonment. Additionally, an independent T-test was utilized to determine if the factors cited varied depending on the role of the person completing the survey. The results of this investigation indicate that it is imperative to consider a complex interaction of factors pertaining to the individuals who use AAC, their conversational partners, settings in which interactions occur, and devices used to interact, when designing an AAC intervention. The statistical analysis revealed no significance difference in how the respondents rated the factors based on their occupation. Based on the results of the study, a checklist of factors that an AAC practitioner might consider addressing in order to foster acceptance of AAC systems initially and later on was constructed

Feedback control logic synthesis for non safe Petri nets

This paper addresses the problem of forbidden states of non safe Petri Net (PN) modelling discrete events systems. To prevent the forbidden states, it is possible to use conditions or predicates associated with transitions. Generally, there are many forbidden states, thus many complex conditions are associated with the transitions. A new idea for computing predicates in non safe Petri nets will be presented. Using this method, we can construct a maximally permissive controller if it exists

Bayesian Design of Tandem Networks for Distributed Detection With Multi-bit Sensor Decisions

We consider the problem of decentralized hypothesis testing under communication constraints in a topology where several peripheral nodes are arranged in tandem. Each node receives an observation and transmits a message to its successor, and the last node then decides which hypothesis is true. We assume that the observations at different nodes are, conditioned on the true hypothesis, independent and the channel between any two successive nodes is considered error-free but rate-constrained. We propose a cyclic numerical design algorithm for the design of nodes using a person-by-person methodology with the minimum expected error probability as a design criterion, where the number of communicated messages is not necessarily equal to the number of hypotheses. The number of peripheral nodes in the proposed method is in principle arbitrary and the information rate constraints are satisfied by quantizing the input of each node. The performance of the proposed method for different information rate constraints, in a binary hypothesis test, is compared to the optimum rate-one solution due to Swaszek and a method proposed by Cover, and it is shown numerically that increasing the channel rate can significantly enhance the performance of the tandem network. Simulation results for $M$-ary hypothesis tests also show that by increasing the channel rates the performance of the tandem network significantly improves

Rate Allocation for Decentralized Detection in Wireless Sensor Networks

We consider the problem of decentralized detection where peripheral nodes make noisy observations of a phenomenon and send quantized information about the phenomenon towards a fusion center over a sum-rate constrained multiple access channel. The fusion center then makes a decision about the state of the phenomenon based on the aggregate received data. Using the Chernoff information as a performance metric, Chamberland and Veeravalli previously studied the structure of optimal rate allocation strategies for this scenario under the assumption of an unlimited number of sensors. Our key contribution is to extend these result to the case where there is a constraint on the maximum number of active sensors. In particular, we find sufficient conditions under which the uniform rate allocation is an optimal strategy, and then numerically verify that these conditions are satisfied for some relevant sensor design rules under a Gaussian observation model.Comment: Accepted at SPAWC 201