background: taking visual acuity is an important part of an eye routine examination. this study was conducted to compare visual acuity measured using an iranian digital tumbling e chart with visual acuity measured using an italian digital tumbling e chart as a familiar foreign chart. materials and methods: this study was carried out on 200 participants (400 eyes; healthy n=40, glaucoma n=40, re...

multivariate control charts such as hotelling`s t^ 2 and x^ 2 are commonly used for monitoring several related quality characteristics. these control charts use correlation structure that exists between quality characteristics in an attempt to improve monitoring. the purpose of this article is to discuss some issues related to the g chart proposed by levinson et al. [9] for detecting shifts in ...

preparing thermal comfort conditions in outdoor public spaces is one of the considerations of architectural design. if the constructed area does not support comfortable conditions in outdoor spaces, it will cause microclimatic problems for pedestrians and adjacent buildings. regarding the different thermal comfort conditions in outdoor spaces in comparison with indoor, several indices have been...

Control chart techniques have been widely used in industries to monitor a process in quality improvement. Whenever we deal with variables data, we usually employ a combination of X-bar chart and R chart (or S chart) to monitor both the center and the spread of the process. In this paper, we propose a simple alternative, that is, we design a single chart to monitor both the center and the spread...

abstract. in recent years several studies have shown that  control charts with adaptive schemes or double sampling plans detect both small and moderate shifts in the process mean more quickly than the traditional shewhart  chart. in the classical double sampling  chart, the difference between two points were placed in the central region of first stage was not considered. in this study, a new co...

purpose: e is a commonly use letter for illiterates or those who could not read english to measure visual acuity. the e chart is the mainly used charts in iran. however, they do not have the standards. they are in different format, fixed for 6 meter test, with or without lighting, with unequal number of letters in each line and different contrasts. as a result, there is an essential need for a ...

The CCC-r chart is developed based on cumulative count of a conforming (CCC) control chart that considers the cumulative number of items inspected until observing r nonconforming ones. Typically, the samples obtained from the process are analyzed through 100% inspection to exploit the CCC-r chart. However, considering the inspection cost and time would limit its implementation. In this paper, w...

In high quality industrial processes, the control chart is design based on cumulative count of conforming (CCC) items is very useful. In this paper, the performance of CCC-r chart with variable sampling intervals (CCC-rVSI chart) in the presence ofinspectionerrors isinvestigated. The efficiency of CCC-rVSI chart is compared with CCC-r chart with fixed sampling interval (CC...