A feasibility approach for constructing combinatorial designs of circulant type

In this work, we propose an optimization approach for constructing various classes of circulant combinatorial designs that can be defined in terms of autocorrelation. The problem is formulated as a so-called feasibility problem having three sets, to which the Douglas–Rachford projection algorithm is applied. The approach is illustrated on three different classes of circulant combinatorial designs: circulant weighing matrices, D-optimal matrices of circulant type, and Hadamard matrices with two circulant cores. Furthermore, we explicitly construct two new circulant weighing matrices, a CW(126, 64) and a CW(198, 100), whose existence was previously marked as unresolved in the most recent version of Strassler’s table.     

Proposal for an integrative methodology to development the ergonomic program

This paper collects the experience for both, academic and professional practice, and deal with the stages and level of involvement from different elements in the organization. The work is focused in some kind of concentric cycles, the very outside circle is formed by those that interact with ergonomic process in a year period, and the inner cycles are those that acts in a daily or weekly intervention. The success of the program still depending on the good will of the managers, but any action directed on benefit of the people at work, enable the moral as well as indicators for health and safety.     

Thermal comfort and personal protective equipment (PPE)

Personal Protective Equipment (PPE) is considered the last preferred solution to an Occupational Safety Health (OSH) system. Brazilian OSH legislation assumes and requires PPE usage to neutralize the possibility of pesticide contamination. This study examines the inadequacy of the PPE used in a tomato crop, particularly from the standpoint of thermal comfort. This study made observations regarding heart rate and body temperature in a controlled environment using a treadmill (with and without PPE) of 12 volunteers; and during the process of rural labor (at rest and in normal work routine) of 2 actual rural workers. Comparing the results of the treadmill test (with and without PPE) which tried to reproduce the same level of effort and environmental conditions of the actual rural work, this study demonstrated that PPE makes thermoregulation harder and tympanic temperature reaches higher values with the same level of effort. Moreover, body temperature increases quickly: with PPE it took 15 minutes to raise 1°C in body temperature, compared to 40 minutes without PPE. The results of this study indicated that the use inadequate PPE might pose thermoregulation risk to rural workers.     

Ergonomics and the inclusion of people with disabilities in a Brazilian workplace

The customization of a secretary workstation at a drama school was the objective of this case study. The investigation involved a 25-year-old illiterate woman with intellectual disabilities and low vision that had been been attending, for over 12 years, a state school for people with disabilities. The customization process, operationalized after a diagnosis was made, focused on environmental rearrangements, with the purpose of meeting the physical and social demands of the workstation. The results of this research are configured in an ergonomic analysis of work associated with an inventory of social skills, applied to people living directly with the participant. Preliminary evaluations indicated the degree of adjustment of labor demands to the personal characteristics of the participant in the customized job.     

Comparing two types of navigational interfaces for Virtual Reality

Previous studies suggest significant differences between navigating virtual environments in a life-like walking manner (i.e., using treadmills or walk-in-place techniques) and virtual navigation (i.e., flying while really standing). The latter option, which usually involves hand-centric devices (e.g., joysticks), is the most common in Virtual Reality-based studies, mostly due to low costs, less space and technology demands. However, recently, new interaction devices, originally conceived for videogames have become available offering interesting potentialities for research. This study aimed to explore the potentialities of the Nintendo Wii Balance Board as a navigation interface in a Virtual Environment presented in an immersive Virtual Reality system. Comparing participants' performance while engaged in a simulated emergency egress allows determining the adequacy of such alternative navigation interface on the basis of empirical results. Forty university students participated in this study. Results show that participants were more efficient when performing navigation tasks using the Joystick than with the Balance Board. However there were no significantly differences in the behavioral compliance with exit signs. Therefore, this study suggests that, at least for tasks similar to the studied, the Balance Board have good potentiality to be used as a navigation interface for Virtual Reality systems.     

Ergonomics in projects of oil platforms in a change context

The context of oil platform design is changing in order to increase competitiveness and be prepared for difficult operations, mainly in fields more distant from the coast, like pre-salt. The currently preceding context is marked by projects guidelines designed to reduce projects and operation costs, including an important reducing in the number of people on board. The main objective of this research is to verify and discuss if the experience of use in platforms designed in a previous context, in which the people on board is practically twice, can contribute and/or can be transferred to new projects. From the ergonomic intervention in the design of two oil platform, with the work of team on board investigated on previous projects as reference, it was possible analyze if the previous use is still applicable to new projects. As a result, about 90% of the recommendations based on use are applicable to the current context. The restrictions on the transfer or operational experience are mainly related to the time of entry of ergonomics in the design process, the subsequent transformations costs and the advance of the execution phase started with the detailed design.     

Open innovation and quality management: the moderating role of interorganisational IT infrastructure and complementary learning styles

This study seeks to explain the influence of quality management on the relationship between open innovation and performance. We propose that, to contribute to open innovation performance, an organisation’s commitment to quality improvement must rely on the combination of its own resources and capabilities and its open innovation partners’ resources and capabilities. Specifically, we examine the moderating role of an interorganisational IT infrastructure and the complementarity of learning styles among an organisation committed to quality improvement and its supply network. Using data from 270 managers of European firms, our results show that the negative effects of quality management on open innovation performance can be overcome by complementing the organisation’s learning style with that of its open innovation partner, particularly, its supply network, and, most importantly, obtaining information technologies compatible with those of its supply network members.     

INDUCING OVERCONFIDENCE

In this study, I present a theory which explains how the influence of others may generate overconfidence. The argument is built on the idea that the more help an agent receives when performing a task, the less informative the score on that task will be relative to the agent's ability to perform it. If an agent is confident, he tends to benefit from more cooperation opportunities simply because he is likely to be perceived as being more skilled. As a result, he remains confident because the future signals he will observe will contain very little information regarding his ability. On the contrary, if the agent is not confident, he will receive more informative scores, which will help him learn his true ability faster. (JEL D81, D83, D84)     

Flexible objective Bayesian linear regression with applications in survival analysis

We study objective Bayesian inference for linear regression models with residual errors distributed according to the class of two-piece scale mixtures of normal distributions. These models allow for capturing departures from the usual assumption of normality of the errors in terms of heavy tails, asymmetry, and certain types of heteroscedasticity. We propose a general non-informative, scale-invariant, prior structure and provide sufficient conditions for the propriety of the posterior distribution of the model parameters, which cover cases when the response variables are censored. These results allow us to apply the proposed models in the context of survival analysis. This paper represents an extension to the Bayesian framework of the models proposed in [16]. We present a simulation study that shows good frequentist properties of the posterior credible intervals as well as point estimators associated to the proposed priors. We illustrate the performance of these models with real data in the context of survival analysis of cancer patients.     

Model selection criteria in beta regression with varying dispersion

We address the issue of model selection in beta regressions with varying dispersion. The model consists of two submodels, namely: for the mean and for the dispersion. Our focus is on the selection of the covariates for each submodel. Our Monte Carlo evidence reveals that the joint selection of covariates for the two submodels is not accurate in finite samples. We introduce two new model selection criteria that explicitly account for varying dispersion and propose a fast two step model selection scheme which is considerably more accurate and is computationally less costly than usual joint model selection. Monte Carlo evidence is presented and discussed. We also present the results of an empirical application.