International Journal for Quality Research

10

Authors: Bahram Sadeghpour Gildeh, Azamsadat Iziy, Bahareh Ghasempour

The capability indices are widely used by quality professionals as an estimate of process capability. Many process indices have been proposed in last few years. A process capability index Cpmk is a generalized version of the existing indices confidence interval estimate for Cpk is defined. A series of Cp, Cpk, Cpm. In this paper the Percentile-t bootstrap (PTB) simulations using Weibull distribution with different parameters and sample size for the index Cpmk was undertaken to compare the performance and reliability of bootstrap method and the effect of parameters of Weibull distribution (shape and scale).

12

Authors: Richard O. Oruko, Wilkister N. Moturi, John M. Mironga

Solid wastes generated in Nairobi and its environs are posing a serious environmental challenge to the authorities and public, especially the hazardous and non-biodegradable solid wastes from leather industries. There were environmental concerns and complaints from workers and residents living adjacent to Asili tanneries limited about degradation of natural and inbuilt environment. This pointed to the effect of environmental pollution by the tannery. The broad objective of study was to assess the effectiveness of tannery based solid wastes management, by identifying and analyzing the concentration levels of sodium chlorides,sulphide, chromium ions and total phenols as selected pollutants along the tanning stages, in Nairobi river, borehole water, and soils around the dump site inside the tannery. Experimental (laboratory analysis) design was used.Descriptive statistics was used in analyzing data resulting in means and tables. The means concentration of total Chrome was 2633.38mg/L,Sodium chloride 609.93mg/L, Sulphide 129.77mg/L, total Phenols 10.91mg/L in the soil sampled around the composite dump site.. In Nairobi river water the means of Sodium chloride was 317.48mg/L, Sulphide 24.00mg/L, total Phenol 3.97mg/L and total Chrome Nil, While means concentration in borehole water, had Sodium chloride detected at 354.73mg/L, Sulphide 6.67mg/L, total Phenol 0.03mg/L and total Chrome as Nil, indicating heavily contaminated ecosystems above the discharge set limits of National Environmental Management Authority and Nairobi city water and sewerage company.

14

Authors: Marija Zahar Djordjevic, Hrvoje Puskaric, Aleksandar Djordjevic

The aim of this study is to propose a fuzzy multi-criteria decision-making approach (MCDM) to evaluate the artificial hip prosthesis suppliers with respect to numerous criteria, simultaneously, taking into account the type of each criteria and its relative importance. The fuzzy of the Technique for Order Preference by Similarity to Ideal Solution (FTOSIS)is applied in order to rank the artificial hip prosthesis suppliers. The rank is obtained using the process of fuzzy number comparison. Software solution based on suggested method is also presented. A real-life example with real data is presented to clarify the proposed method.

14

Authors: Moustafa Omar Ahmed, Abu-Shawiesh, Florence George, B. M. Golam Kibria

This paper proposed and considered some bivariate control charts to monitor individual observations from a statistical process control. Usual control charts which use mean and variance-covariance estimators are sensitive to outliers. We consider the following robust alternatives to the classical Hoteling's T2: T2MedMAD, T2MCD, T2MVE a simulation study has been conducted to compare the performance of these control charts. Two real life data are analyzed to illustrate the application of these robust alternatives.

16

Authors: Asmamaw Tegegne, Tekalegn Argu

These days cost of building materials are continuously increasing and the conventional construction materials for this particular purpose become low and low. The weight of conventional construction materials particularly building block is heavy and costly due to particularly cement. Thus, the objective of this paper is to develop an alternative light weight, high strength and relatively cost effective building material that satisfy the quality standard used in the country. A bio-based polymer matrix composite material for residential construction was experimentally developed. Sugar cane bagasse, thermoplastics (polyethylene g roup) sand and red ash were used as materials alternatively. Mixing of the additives,melting of the hermoplastics, molding and curing (drying)were the common methods used on the forming process of the samples. Mechanical behavior evaluation (testing) of the product was carried out. Totally 45 specimens were produced and three replicate tests were performed per each test type. Quality analysis was carried out for group B material using Ishikawa diagram. The tensile strength of group A specimen was approximately 3 times greater than that of group B specimens. The compression strength of group A specimens were nearly 2 times greater than group B. Comparing to the conventional building materials(concert block and agrostone)produced in the country, which the compression strength is 7Mpa and 16Mpa respectively, the newly produced materials show much better results in which Group A is 25.66 Mpa and group B is 16.66 Mpa. energy absorption capacity of group A specimens was approximately 3 times better than that of group B. Water absorption test was carried out for both groups and both showed excellent resistivity. Group A composite material specimens, showed better results in all parameters.