Assessment of physical workload in boiler operations

The use of boiler wood-fired is fairly common equipment utilized in steam generation for energy production in small industries. The boiler activities are considered dangerous and heavy, mainly due to risks of explosions and the lack of mechanization of the process. This study assessed the burden of physical labor that operators of boilers are subjected during the workday. Assessment of these conditions was carried out through quantitative and qualitative measurements. A heart rate monitor, a wet-bulb globe thermometer (WBGT), a tape-measure and a digital infrared camera were the instruments used to collect the quantitative data. The Nordic Questionnaire and the Painful Areas Diagram were used to relate the health problems of the boiler operator with activity. With study, was concluded that the boiler activity may cause pains in the body of intensity different, muscle fatigue and diseases due to excessive weight and the exposure to heat. The research contributed to improve the boiler operator's workplace and working conditions.     

Evaluation of thermal overload in boiler operators

The Brazilians educational institutions need a large energy demand for the operation of laundries, restaurants and accommodation of students. Much of that energy comes from steam generated in boilers with wood fuel. The laboral activity in boiler may present problems for the operator's health due to exposure to excessive heat, and its operation has a high degree of risk. This paper describes an analysis made the conditions of thermal environment in the operation of a B category boiler, located at a Higher Education Institution, located in the Zona da Mata Mineira The equipments used to collect data were Meter WBGT of the Heat Index; Meter of Wet Bulb Index and Globe Thermometer (WBGT); Politeste Instruments, an anemometer and an Infrared Thermometer. By the application of questionnaires, the second phase consisted of collecting data on environmental factors (temperature natural environment, globe temperature, relative humidity and air velocity). The study concluded that during the period evaluated, the activity had thermal overload.     

Effects of vibration exposure on professional drivers: a field test for quantifying visual and cognitive performance

Effects of whole-body vibration (WBV) exposure on professional drivers were predicted using a 45 subjects sample of healthy volunteers from both genders. These volunteers preformed a visual/motor accuracy evaluation test, the 'omega test', inside a vehicle (van) under three different WBV exposure conditions, van halted, van performing a circuit on asphalt, and on cobblestone. WBV levels of the stated conditions were statistically different and impairment upon subjects' performance was found. The statistical significant difference encountered between the subjects performance under the two whole-body vibration profiles (asphalt and cobblestone), seems to indicate that the vibration levels also represent a variable to be taken under consideration. No gender related difference was found.     

Comparison between occupational noise measurement strategies: why is it important?

The international standard ISO 9612:2009, regarding the determination of occupational noise exposure through an engineering method, establishes a methodology for evaluating the exposure of workers to occupational noise, through the specification of three different strategies, namely: task-based measurement (TBM); job-based measurement (JBM) and; full day measurement (FDM). In this work, questions are raised, "resulting in a literature review regarding the need to test the functionality of the three strategies, through the systematic comparison between them and analysis of their application impact at several levels. There is a need to test the compare these three strategies, since there are no peer-review studies in this domain. In fact, there are still no studies that systematically do the comparison between them and analyze the impact of their application at various levels, such as the precision and accuracy of the results, the required equipment, time spent and, most important, the estimation of the uncertainty associated to the measurements.     

Truncated location-scale non linear regression models

We present a class of truncated non linear regression models for location and scale where the truncated nature of the data is incorporated into the statistical model by assuming that the response variable follows a truncated distribution. The location parameter of the response variable is assumed to be modeled by a continuous non linear function of covariates and unknown parameters. In addition, the proposed model also allows for the scale parameter of the responses to be characterized by a continuous function of the covariates and unknown parameters. Three particular cases of the proposed models are presented by considering the response variable to follow a truncated normal, truncated skew normal, and truncated beta distribution. These truncated non linear regression models are constructed assuming fixed known truncation limits and model parameters are estimated by direct maximization of the log-likelihood using a non linear optimization algorithm. Standardized residuals and diagnostic metrics based on the cases deletion are considered to verify the adequacy of the model and to detect outliers and influential observations. Results based on simulated data are presented to assess the frequentist properties of estimates, and a real data set on soil-water retention from the Buriti Vermelho River Basin database is analyzed using the proposed methodology.     

European industrial districts: Influence of geographic concentration on performance of the firm

This paper reviews ideas and insights from recent firm strategy literature. We argue that these perspectives can be usefully extended to explain the competitive advantage of the industrial district. Most of the empirical studies seeking evidence of the competitive advantage of the industrial district consisted of case studies. This paper attempts to offer a measurement of the performance of industrial district firms on a comparative basis by using the case of the Spanish ceramic tile industry.     

Efficient Estimation of Data Combination Models by the Method of Auxiliary-to-Study Tilting (AST)

We propose a locally efficient estimator for a class of semiparametric data combination problems. A leading estimand in this class is the average treatment effect on the treated (ATT). Data combination problems are related to, but distinct from, the class of missing data problems with data missing at random (of which the average treatment effect (ATE) estimand is a special case). Our estimator also possesses a double robustness property. Our procedure may be used to efficiently estimate, among other objects, the ATT, the two-sample instrumental variables model (TSIV), counterfactual distributions, poverty maps, and semiparametric difference-in-differences. In an empirical application, we use our procedure to characterize residual Black–White wage inequality after flexibly controlling for “premarket” differences in measured cognitive achievement. Supplementary materials for this article are available online.