External grind-hardening forces modelling and experimentation

Grind hardening process utilizes the heat generated in the grinding area for the surface heat treatment of the workpiece. The workpiece surface is heated above the austenitizing temperature by using large values of depth of cut and low workpiece feed speeds. However, such process parameter combinations result in high process forces that inhibit the broad application of grind hardening to smaller grinding machines. In the present paper, modelling and predicting of the process forces as a function of the process parameters are presented. The theoretical predictions present good agreement with experimental results. The results of the study can be used for the prediction of the grind hardening process forces and, therefore, optimize the process parameters so as to be used with every size grinding machine

Sustainability assessment for manufacturing operations

Sustainability is becoming more and more important as a decision attribute in the manufacturing environment. However, quantitative metrics for all the aspects of the triple bottom line are difficult to assess. Within the present paper, the sustainability metrics are considered in tandem with other traditional manufacturing metrics such as time, flexibility, and quality and a novel framework is presented that integrates information and requirements from Computer-Aided Technologies (CAx) systems. A novel tool is outlined for considering a number of key performance indicators related to the triple bottom line when deciding the most appropriate process route. The implemented system allows the assessment of alternative process plans considering the market demands and available resources

Cloud-based Control of Thermal Based Manufacturing Processes

AbstractWith non-conventional manufacturing processes, being increasingly integrated into manufacturing process chains, controllers and control strategies, remote nowadays, have to take into account a plethora of phenomena and criteria. The current study addresses the challenges, associated with the framework of the thermal oriented processes, having holistic (digital) modelling as a main objective. Herein two different case studies are performed; numerical examples regarding big data impact on manufacturing and simulation-based paradigms of control design taking into account communications. Implementation of the aforementioned takes into account the controller's complexity

Manufacturing Resilience during the Coronavirus Pandemic: On the investigation Manufacturing Processes Agility

The unprecedented events that worldwide population experienced during year 2020 due to the COVID-19 pandemic, resulted in the formation of numerous challenges across the majority of aspects of every day life. Manufacturing industries and supply chain networks faced a unique decostruction during this period due to restrictions created by global or local lockdowns. Reduction of human resources availability and transportation restrictions linked with the extreme and rapid increase of demand for medical supplies led manufactring related activities to reach their limits. Moreover, the non flexible manufacturing methods that are employed for the production of this type of equipment as well as the delayed delivery of products that are used as raw material at the early production stages, resulted in market shortage of medical supplies while demand constantly growing. Additive Manufacturing was used for the immediate production of plastic/metal medical equipment, taking advantage of reverse engineering, process flexibility and commercialization of printing devices. Small and large enteprises in cooperation with individuals have been organized into Local Hubs in order to reduce the transportation time and accelerate the supply of the required equipment at local hopitals until the the non flexible production lines manage to produce the desired production volume under the required production rate. This study aims to identify reasons why traditional manufacturing facilies faced such difficulties in the production of medical equipment and to propose a framework where Additive Manufacturing methods can be used for the immediate, local and low volume production of the desired product, giving time to non easily adjustable industries to initiate the mass production

Simplifying the Interaction with User-Defined Types in SQL via a JDBC Wrapper Library

Η Java Database Connectivity (JDBC) είναι μια διεπαφή προγραμματισμού εφαρμογών (API) για τη γλώσσα προγραμματισμού Java, η οποία ορίζει τον τρόπο με τον οποίο ένας πελάτης μπορεί να έχει πρόσβαση σε μια βάση δεδομένων. Το γεγονός ότι είναι βασικό, το καθιστά φλύαρο και κουραστικό για εκτεταμένη άμεση χρήση και αυτό μεγιστοποιείται κατά την ενασχόληση με πιο σύνθετους User-Defined Types (UDT) στην SQL. Η παρούσα διπλωματική εργασία περιγράφει τη διαδικασία υλοποίησης μιας βιβλιοθήκης περιτύλιξης διεπαφής JDBC που απλοποιεί την πρόσβαση στη βάση δεδομένων από την απλή εκτέλεση εντολών SQL σε πιο σύνθετες περιπτώσεις χρήσης με τύπους που ορίζονται από τον χρήστη. Για να το επιτύχουμε αυτό αυτοματοποιούμε και κρύβουμε από τον χρήστη διαδικασίες που έως τώρα το βάρος της υλοποίησης τους έπεφτε στον προγραμματιστή. Τέτοιες διαδικασίες είναι η προετοιμασία και η δήλωση των παραμέτρων εισόδου ή εξόδου, η διαδικασία κατασκευής του αποτελέσματος και άλλα. Τα αποτελέσματα της παραπάνω διαδικασίας ήταν αρκετά ενθαρρυντικά και έδειξαν ότι η βιβλιοθήκη μας καταφέρνει να μειώσει δραματικά τον κώδικα που απαιτείται για τις πράξεις που χειρίζονται τους τύπους που ορίζονται από τον χρήστη, διατηρώντας παράλληλα την χρονική επιβάρυνση σε όχι σημαντικά επίπεδα. Η μείωση της πολυγλωσσίας τείνει να έχει περαιτέρω θετικές επιπτώσεις όπως η μείωση των πιθανοτήτων εμφάνισης σφαλμάτων και η αύξηση της παραγωγικότητας.Java Database Connectivity (JDBC) is an application programming interface (API) for the Java programming language that defines how a client can access a database. Being basic makes it verbose and tedious for extended direct use. This is intensified while dealing with more complex User-Defined Types (UDT) in SQL database language. This thesis outlines the process of implementing a lightweight JDBC wrapper library that intents to simplify database access from simple execute of SQL statements to more complex use cases with user-defined types. To achieve this, we decrease verbosity by automating and hiding from the user many processes that until now their implementation burden has fallen on the developer. Such processes are the resource management, the preparation and declaration of input or output parameters, the process of building the result and more. The results of the above process were quite encouraging and showed that our library manage to dramatically reduce the amount of code (~90%) required for operations handling user-defined types while keeping the time overhead in not considerable levels. Decreasing verbosity tends to have further positive effects such as reducing the chances of errors and increasing productivity