Application of Dempster-Shafer theory in conceptual design of the machining centres

Projektant tijekom razvoja donosi odluke u uvjetima punim neodređenosti, kontradiktornosti i neznanja. Ti uvjeti su više izraženi u ranim fazama procesa projektiranja. Slijedeći to, u ovom članku predstavlja se način uporabe dokaznih sustava koji predstavljaju oblik ekspertnih sustava u kojima se znanje predstavlja i procesira uporabom Teorije funkcije uvjerenja (Dempster-Shafer teorija). Članak je fokusiran na koncepcijsko projektiranje alatnih strojeva tj. određivanje najbolje konstrukcije obradnog centra u fazi koncepcijskog projektiranja za prethodno definiranu skupinu dijelova koja će na njemu biti obrađivana.In the development phase, the designer makes decisions under conditions which are characterized with some degree of uncertainty, contradiction and ignorance. These conditions appear more often in the early phases of the design process. Following this, in this paper is presented the way of using evidential systems which represent a form of expert systems in which knowledge is represented and processed by the function of the Belief Function Theory (Dempster-Shafer theory). The paper is focused on the conceptual design of machine tools, i.e. determination of the best structure of machining centre in the phase of conceptual design for a predefined group of parts that will be machined on them

Technical product risk assessment integration into the enterprise risk management

Europska Unija je početkom devedesetih godina prošlog stoljeća, kroz uvođenje Novog i Globalnog pristupa tehničkoj harmonizaciji i standardizaciji, ostvarila značajno unapređenje u postupku ocjenjivanja usuglašenosti proizvoda na taj način što je zahtjeve za sigurnost tehničkih proizvoda integrirala u proces projektiranja. To je postignuto tako što se u procesu projektiranja preventivno analiziraju i kvantificiraju nivoi rizika u cilju određivanja opsega potrebnih sustava sigurnosti. S druge strane, svjedoci smo ubrzanog razvoja i uvođenja cjelovitih pristupa upravljanja rizicima u poduzeću koji je u suvremenoj poslovnoj praksi objedinjen nazivom Upravljanje rizicima poduzeća (ERM – Enterprise Risk Menagment). Slijedeći to, u radu se preko osnova Novog i Globalnog pristupa Europske Unije daje pristup za integraciju ocjene rizika u smjernicama Novog pristupa u cjeloviti pristup upravljanju rizicima u poduzeću kakav je ERM suglasno standardu ISO 31000:2009.In the nineties of the previous century, the European Union achieved, through introducing the New and Global Approach to technical harmonization and standardization, a significant improvement in the approach to conformity assessment of products, by integrating the requirements for technical products safety into the process of its designing. This was achieved by preventive analysing and quantifying of risk levels in the design process with the objective of determining the scope of the needed safety systems. On the other hand, we have witnessed a rapid development and implementation of holistic approaches to risks management in enterprises, unified in the modern business practice by the name of Enterprise Risk Management (ERM). Going along that line, the paper presents the basis of the EU New and Global Approach and gives an approach to integrating New Approach Directives risk assessment into the holistic approach of risks management in organization, such as ERM

TECHNICAL PRODUCT RISK ASSESSMENT: STANDARDS, INTEGRATION IN THE ERM MODEL AND UNCERTAINTY MODELING

European Union has accomplished, through introducing New Approach to technical harmonization and standardization, a breakthrough in the field of technical products safety and in assessing their conformity, in such a manner that it integrated products safety requirements into the process of products development. This is achieved by quantifying risk levels with the aim of determining the scope of the required safety measures and systems. The theory of probability is used as a tool for modeling uncertainties in the assessment of that risk. In the last forty years are developed new mathematical theories have proven to be better at modeling uncertainty when we have not enough data about uncertainty events which is usually the case in product development. Bayesian networks based on modeling of subjective probability and Evidence networks based on Dempster-Shafer theory of belief functions proved to be an excellent tool for modeling uncertainty when we do not have enough information about all events aspect

Integrating Risk Assessment in the NAD into the ERM Model

In the nineties years of the previous century, the European Union achieved, through introducing the New and Global Approach to technical harmonization and standardization, a significant improvement in the approach to conformity assessment of products, by integrating the requirements for technical products safety into the process of its designing. This was achieved by preventive analyzing and quantifying of risk levels in the design process with the objective of determining the scope of the needed safety systems. On the other hand, we have witnessed a rapid development and implementation of holistic approaches to risks management in enterprises, unified in the modem business practice by the name of Enterprise Risk Management (ERM). Going along that line, the paper presents basis of the E,U New and Global Approach and give an approach to integrating New Approach Directives risk assessment into the holistic approach of risks management in organization, such as ERM

Optimization Model for Machining Processes Design in Flexible Manufacturing Systems

Engineering machining processes realized in flexible machining systems is a highly complex task, especially since it encompasses complex optimization procedures apart from engineering. For a broad array of different workpieces produced in different series it is very difficult to engineer a manufacturing process for attaining maximum processing productivity with minimal production costs. This paper presents a developed postprocessor model enabling automatic generating of the numerical control code for all programs executed simultaneously in the production process on a greater number of machining centers. The model engrosses the different variants of tools in a machining center magazine, a different combination of elements of the machining mode, possibility of the most favorable layout of workpieces on pallets, compliance with the technological requirements in terms of simultaneous tool changes in machining center magazines, the required total processing time and minimal production costs. To that aim has been developed the postprocessor generator, as a program and software system, enabling all programs to be automatically updated based on the set up optimization strategy from tool changes, changes in cutting mode elements and technological operations. Such updated programs contain optimal technological parameters and provide minimal costs of production while at the same time the maximum utilization of tools during manufacture at an exactly specified time

Risk Assessment and Determination of Factors That Cause the Development of Hyperinsulinemia in School-Age Adolescents

Background and Objectives: Hyperinsulinemia and insulin resistance are not synonymous; if the risk of developing insulin resistance in adolescents is monitored, they do not necessarily have hyperinsulinemia. It is considered a condition of pre-diabetes and represents a condition of increased risk of developing DM (diabetes mellitus); it can exist for many years without people having the appropriate symptoms. This study aims to determine the risk of developing hyperinsulinemia at an early age in adolescents by examining which factors are crucial for its occurrence. Materials and Methods: The cross-sectional study lasting from 2019 to 2021 (2 years) was realized at the school children’s department in the Valjevo Health Center, which included a total of 822 respondents (392 male and 430 female) children and adolescents aged 12 to 17. All respondents underwent a regular, systematic examination scheduled for school children. BMI is a criterion according to which respondents are divided into three groups. Results: After summary analyzes of OGTT test respondents and calculated values of HOMA-IR (homeostatic model assessment for insulin resistance), the study showed that a large percentage of respondents, a total of 12.7%, are at risk for hyperinsulinemia. The research described in this paper aimed to use the most popular AI (artificial intelligence) model, ANN (artificial neural network), to show that 13.1% of adolescents are at risk, i.e., the risk is higher by 0.4%, which was shown by statistical tests as a significant difference. Conclusions: It is estimated that a model using three different ANN architectures, based on Taguchi’s orthogonal vector plans, gives more precise and accurate results with much less error. In addition to monitoring changes in each individual’s risk, the risk assessment of the entire monitored group is updated without having to analyze all data

Risk Assessment and Determination of Factors That Cause the Development of Hyperinsulinemia in School-Age Adolescents

Background and Objectives: Hyperinsulinemia and insulin resistance are not synonymous; if the risk of developing insulin resistance in adolescents is monitored, they do not necessarily have hyperinsulinemia. It is considered a condition of pre-diabetes and represents a condition of increased risk of developing DM (diabetes mellitus); it can exist for many years without people having the appropriate symptoms. This study aims to determine the risk of developing hyperinsulinemia at an early age in adolescents by examining which factors are crucial for its occurrence. Materials and Methods: The cross-sectional study lasting from 2019 to 2021 (2 years) was realized at the school children’s department in the Valjevo Health Center, which included a total of 822 respondents (392 male and 430 female) children and adolescents aged 12 to 17. All respondents underwent a regular, systematic examination scheduled for school children. BMI is a criterion according to which respondents are divided into three groups. Results: After summary analyzes of OGTT test respondents and calculated values of HOMA-IR (homeostatic model assessment for insulin resistance), the study showed that a large percentage of respondents, a total of 12.7%, are at risk for hyperinsulinemia. The research described in this paper aimed to use the most popular AI (artificial intelligence) model, ANN (artificial neural network), to show that 13.1% of adolescents are at risk, i.e., the risk is higher by 0.4%, which was shown by statistical tests as a significant difference. Conclusions: It is estimated that a model using three different ANN architectures, based on Taguchi’s orthogonal vector plans, gives more precise and accurate results with much less error. In addition to monitoring changes in each individual’s risk, the risk assessment of the entire monitored group is updated without having to analyze all data