Thermoforming of Thin-Ply Composite Structures via In-Situ Heating

This thesis investigates thermoforming of thin-ply thermoplastic composites via in-situ heating for in-space manufacturing applications. The proposed composite concept is based on combining conductive carbon nanotube (CNT) films and high-temperature thermoplastic matrix. The CNT film is made of randomly aligned carbon nanotubes, which possesses outstanding electrical, thermal, and mechanical properties. When combined with polymer matrix, it becomes a multifunctional composite structure. The thermoplastic chosen is polyether ether ketone (PEEK), which is a semicrystalline high-performance thermoplastic that has exceptional physical and mechanical properties at high temperatures. The composite structure studied is consists of a layer of CNT film sandwiched between two thin films of PEEK. The CNT acts as an in-situ conductive heater when a voltage difference is applied, and a mechanical reinforcement. The PEEK polymer impregnated with reinforcement fibers and CNT is capable of reforming by repeating the thermoforming process. The focus of this study is on developing and characterizing the manufacturing process suitable for in-space manufacturing, where CNT/PEEK can be treated as a composite prepreg capable of being reformed into different shapes on demand via thermoforming. The thermoforming of thin-ply composite structures is achieved solely via in-situ electrical heating

Conscience in Crisis: The Need for a Better Understanding of Conscience

Thesis advisor: James KeenanThesis advisor: Dominic DoyleThesis (STL) — Boston College, 2022.Submitted to: Boston College. School of Theology and Ministry.Discipline: Sacred Theology

PRIMENA HEART METODE ZA PROCENU LJUDSKE POUZDANOSTI – SRPSKO ISKUSTVO

In complex industrial systems, human error has been cited as a cause or a contributing factor in accidents and disasters. The need for improved Human Reliability Assessment (HRA) methodologies that should be applied in Probabilistic Safety Assessments, ever since the early 1990s, has motivated a number of major activities in research and development worldwide. Therefore, the main purpose of this paper is to show the practical application of Human Error Assessment and Reduction Technique (HEART) for HRA in Electric Power Company of Serbia (EPCS). The usefulness of this technique for HRA has been approved in a case study of an accident which occurred during a repair on a 10/0.4 kV steel lattice tower “Maričiće“, Kuršumlija (jurisdiction of EPCS, ED “Jugoistok”, Nis, Serbia). For the purpose of this study, a database on work-related injuries, accidents, and critical interventions that occurred over a 10-year period was created. The research comprised an analysis of 1074 workplaces, with a total of 3997 employees. The case study performed at the EPCS confirmed that the HEART is based on knowledge of human activities and relies on expert opinion to determine the Error Producing Condition (EPCs) that affected the situation. The HEART can be used in different industrial systems, as a risk assessment, accident investigation and design tool. In addition, it is a relatively fast tool for assessment of human error probability that is easily applied and understood. U kompleksnim industrijskim sistemima ljudska greška je često navedena kao uzrok ili glavni faktor koji dovodi do akcidenata i katastrofa. Potreba za poboljšanim metodologijama za procenu ljudske pouzdanosti, koje se primenjuju u probabilističkoj proceni bezbednosti, još od ranih 1990-tih motivisala je brojna istraživanja. Glavni cilj ovag rada je da prikaže praktičnu primenu “Tehnike za procenu i redukciju ljudske greške” u proceni ljudske pouzdanosti u preduzeću “Elektroprivreda Srbije”. Korisnost ovog alata, za ovu namenu, dokazana je u studiji slučaja u kojoj je izvršena analiza akcidenta do koga je došlo prilikom intervencije na čelično-rešetkastoj TS 10/0,4kV „Maričiće“, Kuršumlija, ED „Jugoistok“, Niš. Za potrebe ove studije kreirana je baza podataka o povredama na radu, akcidentima i kritičnim intervencijama u poslednjih 10 godina. Istraživanje je obuhvatilo analizu 1074 radna mesta sa ukupno 3997 zaposlenih. Studija slučaja koja je sprovedena u Elektroprivredi Srbije potvrdila je da se “Tehnika za procenu i redukciju ljudske greške” zasniva na poznavanju aktivnosti operatora i da za procenu “uslova za nastanak greške”, koristi stručno mišljenje eksperata. Tehnika za procenu i redukciju ljudske greške može da se koristi u različitim industrijskim sistemima kao alat za procenu rizika, analizu akcidenata i projektovanje. To je relativno brz, lako razumljiv i jednostavan alat za procenu verovatnoće ljudske greške