Adriano Mendonça Souza

Comparative study of the performance of the CuSum and EWMA control charts

Abstract This work presents a comparative study of the performance of the cumulative sum (CuSum), as well as the exponentially weighted moving average (EWMA) control charts. The objective of this research is to verify when CuSum and EWMA control charts do the best control region, in order to detect small changes in the process average. Starting from the data of a productive process, several series were simulated. CuSum and EWMA control charts were used to determine the average run length (ARL) to detect a condition out of control. ARL found by each chart which was then, compared. It was observed that the CuSum control chart practically did not sign points out of control for the levels of variation between ±1.0 standard deviation. For these variation levels the EWMA control chart was more efficient than CuSum. Among the parameters EWMA control chart the ones with constant λ=0.10 and 0.05, with the respective control limits L=2.814 and 2.625, were the ones that detected larger number of altered positions.

Orientação para aprendizagem, orientação para mercado e desempenho organizacional: evidências empíricas

Abstract This study aims to identify how learning orientation (LO) and market orientation (MO) influence the performance of enterprises in the central region of the state of Rio Grande do Sul (RS), Brazil. The method used involved a survey of 123 companies in central RS. The instrument for data collection was developed using the LO scale (Sinkula, Baker, & Noordewier, 1997), the MARKOR scale (Kohli, Jaworski, & Kumar, 1993) and items for evaluation of organizational performance proposed by Narver and Slater (1990) and Baker and Sinkula (1999). The results suggest that MO has a significant positive influence on the organizational performance of the companies surveyed. It was also noted that the MO significantly influences organizational performance when mediated by the LO, just as the LO has a significant influence on organizational performance when mediated by MO. Key words : market orientation; learning orientation; strategy; organizational performance; structural equations.

Qualidade na prestação de serviços fisioterápicos: estudo de caso sobre expectativas e percepções de clientes

A presente dissertacao aborda a qualidade na prestacao de servicos fisioterapicos atraves da comparacao entre expectativas e percepcoes de clientes. O estudo foi desenvolvido junto aos praticantes de Pilates de uma clinica de Fisioterapia da cidade de Santa Maria RS. Para avaliar a qualidade dos servicos, utilizou-se a Escala SERVQUAL, cuja caracteristica e possibilitar a comparacao entre as expectativas que os clientes tem sobre a prestacao de um determinado servico com as suas percepcoes sobre o mesmo. Oitenta e seis clientes participaram do estudo. Os dados provenientes da Escala SERVQUAL adaptada para a presente pesquisa foram submetidos a Estatistica Descritiva e, das 22 questoes constituintes da Escala, em 12 delas a percepcao de qualidade foi superior as expectativas. Tres questoes apresentaram medias muito parecidas entre as expectativas e percepcoes e, em sete questoes, as expectativas foram superiores as percepcoes. Alem da Estatistica Descritiva, os dados tambem foram submetidos a Analise Estatistica Multivariada, a fim de verificar a presenca ou nao de questoes redundantes na Escala SERVQUAL adaptada a Fisioterapia. A aplicacao de Estatistica Multivariada permitiu a retirada de questoes redundantes mediante criterios de exclusao. Assim, nove questoes foram eliminadas do questionario, acarretando uma diminuicao de apenas 8,828% na variância total entre a versao original e a reduzida. Este estudo possibilitou detectar pontos de melhoria nos servicos prestados pela clinica constituinte do caso e, alem disso, sugeriu uma Escala SERVQUAL com menor numero de questoes, sem perda significativa em sua abrangencia. Com isso, outros segmentos do setor de servicos poderao se beneficiar da versao mais enxuta da ferramenta SERVQUAL e facilitar suas pesquisas.

Identificação de variáveis fora de controle em processos produtivos multivariados

Most productive processes are affected by multiple variables and generate a great amount of data and simultaneous monitoring becomes necessary. Thus, the main purpose of this work is to show, by means of an example, procedures of identification of variables responsible for process instability. It considers weakly and strongly correlated variables. The behavior of these variables is analyzed, initially by means of a Hotteling‘s T2 chart for the verification of the process stability. When the process is considered to be out-of-control, another investigation is carried out. For variables of weak correlation an X-bar chart with Bonferroni limits is used. For variables of strong correlation, the data are decomposed in principal components and analyzed by means of a X-bar control chart. In both cases, the techniques used can correctly identify the variable responsible for the process instability, as well as the period of disturbance.

Gráfico de controle de regressão aplicado na monitoração de processos

The main purpose of this research is to apply the regression control chart as tool of statistical control to monitor productive processes, where a state variable that is of interest can be expressed as function of a control variable. Several studies exist to control variables in productive processes, but most of time they are separately in relation to the control of each variable, and however not could be used for a comparative study. This research, therefore, it presents an efficient technique to control simultaneous by correlated variables.

Multivariate feed back control: an application in a productive process

The main purpose of this research is to implement a multivariate feedback adjustment proportional to the last deviation from the target, in the set of variables wandering around the target. To apply the controller equation it will be necessary to study the exponentially weighted moving average (EWMA) statistic, in order to determine the behavior of the target disturbances. To determine the forecast values of the variables we will use Seemingly Unrelated Regression (SUR), which is necessary since there is a relationship between the variables and between the errors. In this manner, multivariate feedback adjustment can be reached based on scientific grounds. q 2004 Elsevier Ltd. All rights reserved.

Situation awareness and computational intelligence in opportunistic networks to support the data transmission of urban sensing applications

Abstract Smart cities can be seen as large-scale Cyber-Physical Systems with sensors monitoring cyber and physical indicators and with actuators dynamically changing the complex urban environment in some way. In this context, urban sensing is a new paradigm that exploits human-carried or vehicle-mounted sensors to ubiquitously collect data to provide a holistic view of the city. A challenge in this scenario is the transmission of sensed data in situations where the networking infrastructure is intermittent or unavailable. This paper outlines our research into an engine that uses opportunistic networks to support the data transmission of urban sensing applications. It applies situation awareness and computational intelligence approaches to perform routing, adaptation, and decision-making procedures. We carried out simulations within a simulated environment that showed our engine had 12% less overhead than other compared approaches.

Avaliação do processo de ensino: uma abordagem multivariada

A pratica da qualidade na gestao universitaria se faz com o comprometimento de toda comunidade escolar. Assim, atraves da avaliacao do processo de ensino, o presente trabalho objetivou identificar, na opiniao do discente, os pontos fracos e fortes do processo de ensino, por meio da analise multivariada. Assim sendo, para este estudo, foram considerados questionarios que abrangeram as categorias de variaveis: 1) auto-avaliacao do aluno, 2) avaliacao da importância dos conteudos para o curso e o desempenho pedagogico do professor, 3) avaliacao docente pelo discente e 4) avaliacao discente pelo docente. Os dados obtidos no final de 2003 compuseram a primeira amostra que apresentou uma participacao de 54% dos alunos do curso de administracao em comercio exterior. Os dados referentes ao processo de avaliacao realizado ao final de 2005 corresponderam a uma participacao de 87% dos alunos matriculados nos cursos de graduacao da Instituicao de Ensino Superior IES. As informacoes foram processadas utilizando-se a tecnica estatistica de analise fatorial com rotacao varimax normalizada. Da analise fatorial, resultaram fatores, com consistencia interna satisfatoria que definiram as dimensoes: 1) situacoes de estimulo por parte do professor para o aluno buscar conhecimento com uma explicacao de 50%, 2) com 21% de explicacao os alunos referiram-se as relacoes entre conteudos e objetivos do curso e suas aplicacoes praticas como satisfatorias, 3) situacoes metodologicas apropriadas para o processo de ensino e aprendizagem com 11% de explicacao e como ponto fraco no processo de ensino, 4) a interdisciplinaridade nao foi percebida pelo aluno com a real importância e 5) a frequencia a biblioteca e o habito da leitura devem ser bem mais motivados como tambem a participacao em eventos, a pesquisa e extensao. Os resultados mostraram, por meio de consistencia interna dos fatores, a validez do construto que da suporte ao processo de ensino desta IES. Desse modo, essa forma de analise favorece uma melhor observacao dos gestores nas percepcoes que os alunos tem sobre o processo de ensino em determinada situacao, possibilitando, assim direcionar investimentos em busca da qualidade.

Bacteria and fungal spores as ice nuclei from Coffea arabical L.

Airborne microorganisms from bacterial and fungal species are able toact as ice nuclei and can affect sensible crops to frost such as coffee trees.Consequently, frost is one of the major problems in South-Southeasterncoffee crops in Brazil. In this research, it was found three categories oforganisms with ice nuclei activity (INA) in coffee leaves, basing in themean freezing point of saline solution, around -17oC. The first category,with strong INA, it was found the Pseudomonas syringae var. garceae, acoffee tree pathogenic, as INA+. Pseudomonas syringae var. syringaebehaves with soft less INA+ efficiency, comparing to the var. garceae.This last variety also causes aureolar spot disease. The second categorypresents a partial ice nuclei activity, including two other bacteria, Pantoeaagglomerans (that is known as ice nuclei), and Corynebacterium, withmean freezing point from -7oC to -10oC. And the third category presentsnon-ice nuclei activity (INA-), with freezing point below -11oC, includingall other bacteria and fungi. Additionally, H.vastatrix, acoffee rust disease,which already causes lots of prejudice to the crops, can be associatedwith an INA+ bacterium, causing frost. That result deserves a refinedresearch, trying to elucidate how this association should be done.74UFSM, 33 (2)Therefore, two rust coffee diseases and aureole spot, as well as the presenceof Pantoea agglomerans, can be directly or indirectly associated to icenuclei activity, demanding a higher bio-control, particularly duringwintertime, due the possibility of frost damage.

Previsão do preço dos principais grãos produzidos no Rio Grande do Sul

The aim of this research was to make predictions for 2007, referring to the price of temporary crops developed in the Rio Grande do Sul state. The data-base of the amout produced of the major grain analyzed were the annual average1995 to 2006 and price produced, from January 1995 to December 2006. To accomplish the forecasts in relation to prices of soybean, rice and sweetcorn in RS state, it was used the Box & Jenkins methodology. To such cultivations, the methodoly showed many significant models, however, through the penalizing criterias, AIC e SBC, in addition to the square average error, it was possible to choose the best model for each serie, being the model ARIMA (0,1,2)(0,1,0) to soybean; the model SARIMA (1,1,0)(1,0,1) to rice and the model ARIMA (2,1,1)(0,1,0) to sweetcorn.