Occurrence Of Quality Defects Research Articles

Welfare and meat quality of lambs

Recently, in many parts of the world, greater importance has been given to lamb meat as well as to the intensive production of lamb and sheep, due to demand for this type of meat at affordable prices. In Serbia, similar to most European countries, the structure of total sheep meat production comprises about 70% lamb meat and 30% sheep meat. This study assessed resource-based measures on 11 dairy sheep farms and investigated, in a total of 30 lambs, the effects of sex, the presence of bruises and pneumonia in carcasses, and carcass and meat quality. Carcass (carcass length, thigh length, croup width, subcutaneous fat thickness, presence of bruises) and meat quality (pH, temperature, drip, thawing and cooking losses, color, and meat quality classes) traits were measured post mortem. The most common deficiencies on farms were high stocking density, poor hygienic conditions, dirty drinkers, and lack of outdoor access. Regarding sex differences, higher prevalences of carcass bruises and severe pneumonia were recorded in male lambs. Meat pH (pH45min), sensory color score, and prevalence of dark, firm and dry (DFD) meat were higher in lambs with carcass bruises. The occurrence of quality defects (DFD meat) was higher in lambs with severe pneumonia. It can be concluded that it is necessary to improve the welfare conditions on the lamb farms and pre-slaughter conditions in order to achieve better lamb meat quality.

Evaluating different stakeholder impacts on the occurrence of quality defects in offsite construction projects: A Bayesian-network-based model

Abstract Offsite construction has been identified as an effective approach for enhancing the sustainability of the construction industry. However, due to the fragmented production processes of offsite construction, quality defect control has become a significant challenge in the promotion of offsite construction projects. Offsite construction projects involve multiple interdependent stakeholders in close collaboration. These stakeholders play various roles in quality management and have different degrees of impact on the occurrence of quality defects. To enhance quality defect management in offsite construction projects, it is important to evaluate the different stakeholder impacts on the occurrence of quality defect. Through impact evaluations, critical stakeholders can be identified and their responsibilities clarified with respect to project quality, thereby motivating these key stakeholders to improve their quality defect control. In this study, we developed an evaluation model using the Bayesian network approach to measure stakeholder impacts on defect occurrence in offsite construction projects. Quality defects and stakeholder-related factors that might incur defects were modeled as a Bayesian network and the dependencies among network nodes examined. Then, the stakeholder impacts on the occurrence of quality defects were evaluated using Bayesian analysis. Finally, this Bayesian-network-based evaluation model was applied to a real project in Shenzhen, China. The results indicate that use of precast components with quality defects, misoperations by construction workers, and ineffective quality inspection and testing during onsite assembly and construction were the major factors affecting quality defect control. Additionally, in this case study, we found the contractor to have the highest level of impact on the occurrence of quality defects. This study contributes to the fields of stakeholder impact evaluation and quality defect analysis, and links defect management with key project stakeholders.

Human reliability in manual assembly systems: a Systematic Literature Review.

Human error in manual assembly systems affects system reliability, safety and it is one of the most important causes of quality defects. Many researchers have developed methods for Human Reliability Analysis (HRA) with the aim of identifying, modeling, quantifying and reducing human error, mainly in safety-critical industries. This paper addresses human reliability analysis in assembly systems, where most of the employed workforce is currently involved. The main purpose is to systematically investigate the current state-of-the-art on this topic, analyzing and summarizing the theoretical and empirical contents, identifying patterns and research streams, informing the strengths and weakness of selected literature and so highlighting the research and practice opportunities. The results of this study show that a prospective analysis of human reliability in the manual assembly systems until now has been neglected in literature. Nevertheless, HRA methods and assembly specific methodologies and approaches found in literature can be successfully applied to assembly systems, allowing users to predict human error probability and to determine the most significant error influencing factors. Furthermore, the results highlight the role of human error in the occurrence of quality defects (rejected or reworking). This paper, therefore, contributes to the transfer of knowledge about human reliability gained in manual assembly operations, providing practitioners and researchers with a comprehensive overview of this topic and several research opportunities for future studies.

Somatic Cell Counts Affecting the Casein Fractions of Pasteurized Semi-Skimmed Milk during Storage

Mastitis is generally recognized as an important factor that influences the quality of milk and dairy products. Milk from infected cows is characterized by increased Somatic Cell Counts (SCC) associated with changes in the components and properties of raw milk. The aim of this study was to evaluate the effects of SCC in raw milk on the casein fractions of semi-skimmed pasteurized milk during storage. Raw milk were categorized in SCC groups of low ( 75×104 cells∙mL-1). Four replicates of semiskimmed (1.3-1.4%) pasteurized milk within each SCC category were analyzed for composition, pH, titratable acidity and casein fractions by high performance liquid chromatography after 1, 7, 14, 21 and 28 days of storage. No effect of SCC was observed on the physical-chemical parameters and concentrations of αs-casein, β-casein and κ-casein in pasteurized milk during storage at 5oC. However, chromatograms of milk samples containing high SCC (>75×104 cells∙mL-1) showed increased breakdown products of αs1-casein starting on the seventh day of storage. Results of this trial indicate that SCC in raw milk should not exceed 4x105 cells∙mL-1, to prevent the degradation of casein fractions in pasteurized semi-skimmed milk and the occurrence of quality defects during storage.

Automatic Process Control in Press Shops

The manufacturing of automotive body components in press lines is a sensitive process. The quality characteristics of body components vary. These fluctuations are rooted in the fact that the factors influencing the component quality are varying, e.g., fluctuations of batches regarding material quality, abrasion or heating of the tool during the production cycle. If a certain quality characteristic exceeds a predefined range an intervention in the process is necessary. This intervention is based upon the subjective know-how of the machine operator. Objective information about the state of the process, like tool temperature or the material quality of the semi-finished product is not available. Therefore, a lack of knowledge emerges in the interrelations between the tuning parameters of the system press-tool and the component quality during different stages of the process (material quality, temperature…). In this paper a complete concept for an automatic process control in press shops is described. The concept will be realized in a pilot plant for mass production in the press shop of AUDI AG. The mechanisms of occurrence of quality defects are shown in the paper, as well as the essential factors influencing the quality during the mass production of body components in the automotive industry and their variation. A sensor-system for continuous measurement of influencing variables during the mass production is presented. The key element of the concept is the non-destructive identification of material-properties for every single blank. By associating the sensor-data with the respective quality, a knowledge-based process control can be realized. The purpose is to create a failure prediction algorithm and make optimal adjustments for each stroke of the moulding press, respectively. The potential of existing actuators in modern press lines as well as new, tool integrated proposals for actuators are highlighted.