<p> High-speed machining (HSM) concepts were developed in response to productivity, quality and cost concerns. Significant advancements in controls and machining technologies have recently come together to enable the wide spread use of HSM on the plant floor. However, with the advancement of HSM technology, dynamic problems associated with modern machine-tool structures have not been fully addressed and are currently limiting performance in some applications. <p> A key aspect in the modelling of HSM processes is capturing the dynamics of the system during cutting. Machining over a wide range of rotational speeds necessitates the inclusion of many more higher modes in the system than traditionally considered. In addition many of the instruments used to assess performance such as force dynamometers are not designed to measure the cutting forces at high rotational speeds and hence the specific cutting force values being used are often times not being estimated properly. </p> <p> Thus the focus of this research is to develop a new procedure for predicting the specific cutting forces in the end-milling process for high-speed machining. An improved mechanistic model to predict the specific cutting force using acceleration data captured from the workpiece fixture was developed. The development of the new procedure has also lead to an improvement in the extraction technique used to establish the modal parameters of a machining system. This new extraction technique was found to be more flexible and easier to use than other available techniques. </p> <p> The new procedure was investigated to test the effect of choosing the number of modes of the improved modal parameters extraction technique on the estimation of the specific cutting force. The effect of filtrating the acceleration signal and the importance of including the run-out of the cutting tool in the model were also investigated. </p> <p> The new procedure was tested on different setups and with different cutting force models. Experimental validation of the proposed estimation procedure was carried out, analyzed and compared to the open literature. The new procedure was found to be more accurate while being easier to implement. </p> / Thesis / Doctor of Philosophy (PhD)

The prevalence of side-channel attacks exploiting hardware vulnerabilities leads to the exfil- tration of secretive data such as secret keys, which poses a significant threat to the security of modern processors. The RISC-V BOOM core is an open-source modern processor design widely utilized in research and industry. It enables experimentation with microarchitec- tures and memory hierarchies for optimized performance in various workloads. The RISC-V BOOM core finds application in the IoT and Embedded systems sector, where addressing side-channel attacks becomes crucial due to the significant emphasis on security. While prior studies on BOOM mainly focus on the side channel in the memory hierarchy such as caches or physical attacks such as power side channel. Recently, the front-end of microprocessors, which is responsible for fetching and decoding instructions, is found to be another potential source of side-channel attacks on Intel Processors. In this study, I present four timing-based side-channel attacks that leverage components in the front-end of BOOM. I tested the effectiveness of the attacks using a simulator and Xilinx VCU118 FPGA board. Finally, I provided possible mitigation techniques for these types of attacks to improve the overall security of modern processors. Our findings underscore the importance of identifying and addressing vulnerabilities in the front-end of modern pro- cessors, such as the BOOM core, to mitigate the risk of side-channel attacks and enhance system security. / Master of Science / In today's digital landscape, the security of modern processors is threatened by the increasing prevalence of side-channel attacks that exploit hardware vulnerabilities. These attacks are a type of security threat that allows attackers to extract sensitive information from computer systems by analyzing the physical behavior. The risk of such attacks is further amplified when multiple users or applications share the same hardware resources. Attackers can ex- ploit the interactions and dependencies among shared resources to gather information and compromise the integrity and confidentiality of critical data. The RISC-V BOOM core, a widely utilized modern processor design, is not immune to these side-channel attacks. This issue demands urgent attention, especially considering its deploy- ment in data-sensitive domains such as IoT and embedded systems. Previous studies have focused on side-channel vulnerabilities in other areas of BOOM, ne- glecting the front-end. However, the front-end, responsible for processing initial information, has recently emerged as another potential target for side-channel attacks. To address this, I conducted a study on the vulnerability of the RISC-V BOOM core's front-end. By conduct- ing tests using both a software-based simulator and a physical board, I uncovered potential security threats and discussed potential techniques to mitigate these risks, thereby enhanc- ing the overall security of modern processors. These findings underscore the significance of addressing vulnerabilities in the front-end of processors to prevent side-channel attacks and safeguard against potential malicious activities.

Neonatal palliative care (NPC) is an emerging subset of care in United States (US) neonatal intensive care units (NICUs) that provides relief for both infants and families at the end of life for infants with terminal diagnoses. Families play a large role in the decision-making process for their infant, but their experiences with and perceptions of the support and care provided to them via NPC is unclear. This literature review summarizes the state of knowledge on parents' perspectives of NPC while focusing on the specific factors that influence their experiences and satisfaction with NPC. This literature review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Findings of the literature review broadly include the importance of consistent communication with providers, parental involvement in the care process, and the minimization of infant suffering. Providers must focus on these important quality indicators to ensure they provide the best care possible to the patients and families that they serve. Further research must be done to investigate parent satisfaction and needs in relation to NPC more deeply and to develop interventions and protocols that better incorporate these needs.

No description available.

No description available.

The end-Triassic Mass Extinction (ETME) was one of the "Big 5" mass extinctions of the Phanerozoic and is thought to have been caused by a series of environmental changes triggered by the emplacement of the Central Atlantic Magmatic Province (CAMP). While the overall driver of the ETME is well-accepted, the specific roles of subsequent environmental changes in driving the extinction remain unresolved due to both spatial and temporal biases within existing geochemical records. Additionally, recent studies suggest that environmental deterioration may have preceded the emplacement of both CAMP and the ETME. Here, we present nitrogen isotope (δ15N) and iron speciation data from a sedimentary succession located in Grotto Creek, Alaska in order track changes in the marine nitrogen cycle and redox across the upper Norian Stage of the Triassic through lower Hettangain Stage of the Jurassic (~215 to 198 million years ago). The geologic succession at Grotto Creek represents deeper water marine deposition in eastern equatorial Panthalassa, likely capturing regional oceanic redox trends. δ15N records from Grotto Creek show a pronounced positive excursion of +3‰ that initiates in the upper Norian, peaks near the Norian-Rhaetian boundary (NRB; ~208.5), and declines through the ETME and into the Hettangian. Throughout this interval, iron speciation data show persistent anoxic conditions and occasional euxinia occurred in the local bottom waters. We propose that the positive δ15N and iron speciation data from Grotto Creek reflect a progressive deoxygenation of the upper water column with the expansion of the equatorial oxygen minimum zone (OMZ). Specifically, the δ15N excursion reflects a shift in the dominant processing of bioavailable nitrogen from uptake and nitrification under oxic conditions to incomplete denitrification followed by complete denitrification as deoxygenation progressed. Records from existing study sites in other regions of the Panthalassa reflect similar redox fluctuations and support that this deoxygenation was a regional phenomenon. Other recent studies of the Late Norian and Rhaetian also document declines in biodiversity that predate the ETME, as well as, carbon isotope excursions, likely reflecting perturbations to the carbon cycle. Together, this evidence suggests that increasingly low-oxygen conditions initiated at least ~8 Ma before the emplacement of CAMP and likely paved the way for the ETME. / Master of Science / The end-Triassic mass extinction (ETME) occurred ~ 201 million years ago and was associated with a large drop in global diversity. The extinction is thought to be due to a warming climate resulting from greenhouse gasses released during the eruption of the Central Atlantic Magmatic Province (CAMP). Although the ETME is one of the largest extinction events of the last ~500 million years, the environmental changes leading to the extinction, and before the CAMP eruption, are not well understood. We studied the Grotto Creek section in Alaska which is a sequence of sedimentary rocks that record the deep ocean environment from the ancient Panthalassa or Paleo-Pacific Ocean. This section also provides a relatively complete record of the time before, during, and after the ETME. Here, we present the stable isotopes of nitrogen (δ15N) from these rocks that show disturbances to the nitrogen cycling that occurred in the ocean more than ~ 8 million years before the ETME. We show that δ15N and iron data from Grotto Creek document falling ocean oxygen levels before the ETME. We also find that our δ15N agrees with other environmental proxies that also reflect declining oxygen levels in the oceans along with decreases in marine animal diversity well before the ETME. These geochemical records help to show a more complete picture of how environments changed in the Panthalassa before the ETME

Thesis advisor: Andrea Vicini / Thesis advisor: Daniel Daly / Thesis (STL) — Boston College, 2023. / Submitted to: Boston College. School of Theology and Ministry. / Discipline: Sacred Theology.

End-to-end encryption is becoming a standard feature in popular mobile chat appli-cations (apps) with millions of users. In the two years a number of leading chat apps have added end-end encryption features including LINE, KakaoTalk, Viber, Facebook Messenger, and WhatsApp.However, most of these apps are closed-source and there is little to no independent ver-ification of their end-to-end encryption system design. These implementations may be a major concern as proprietary chat apps may make use of non-standard cryptographic algorithms that may not follow cryptography and security best practices. In addition, governments authorities may force chat app providers to add easily decryptable export-grade cryptography to their products. Further, mainstream apps have a large attack surface as they offer a variety of features. As a result, there may be software vulnera-bilities that could be exploited by an attacker in order to compromise user’s end-to-end privacy. Another problem is that, despite being closed-source software, providers often market their apps as being so secure that even the provider is not able to decrypt messages. These marketing claims may be potentially misleading as most users do not have the technical knowledge to verify them.In this Master’s thesis we use KakaoTalk – the most popular chat app in South Korea – as a case study to perform a security and privacy assessment and audit of its “Secure Chat” opt-in end-to-end encryption feature. Also, we examine KakaoTalk’s Terms of Service policies to verify claims such as “[. . . ] Kakao’s server is unable to decrypt the encryption [. . . ]” from a technical perspective.The main goal of this work is to show how various issues in a product can add up to the potential for serious attack vectors against end-to-end privacy despite there being multiple layers of security. In particular, we show how a central public-key directory server makes the end-to-end encryption system vulnerable to well-known operator-site man-in-the-middle attacks. While this naive attack may seem obvious, we argue that (KakaoTalk) users should know about the strength and weaknesses of a particular design in order to make an informed decision whether to trust the security of a chat app or not. / End-to-end kryptering är en allt mer vanligt förekommande funktionalitet bland populära mobila chatttjänster (händanefter appar) med miljontals användare. Under de två senaste åren har många ledande chattappar, bland annat LINE, KakaoTalk, Viber, Facebook Messenger, och WhatsApp, börjat använda end-to-end kryptering. Dock så är de flesta av dessa appar closed-source och det finns begränsad, eller ingen, fristående granskning av systemdesignen för deras end-to-end kryptering. Dessa implementationer kan innebära en stor risk då proprietära chattappar kan använda sig av kryptografiska algoritmer som inte följer best practice för säkerhet eller kryptografi. Vidare så kan statliga myndigheter tvinga de som tillhandahåller chattappar att använda lättdekrypterad export-grade kryptografi för sina produkter. Lägg till det att de flesta vanliga appar har många ytor som kan attackeras, till följd av all funktionalitet de erbjuder. Som ett resultat av detta finns en risk för mjukvarubrister som kan utnyttjas av en hackare för att inkräkta på en användares end-to-end integritet. Ytterligare ett problem är att trots att det är closed-source mjukvara så marknadsför ofta appleverantörerna sina appar som att vara är så säkra att inte ens leverantörerna själva kan dekryptera användarnas meddelanden. Det som hävdas i marknadsföringen riskerar vara missledande eftersom de flesta användarna inte har den tekniska kunskap som krävs för att kunna verifiera att det som hävdas är sant. I den här Master-uppsatsen använder vi KakaoTalk – den mest populära chattappen i Sydkorea – som en fallstudie för att granska och bedömma säkerhetens- och integritets-aspekterna hos deras valbara “Secure Chat” med end-to-end krypteringsfunktionalitet. Vi granskar även KakaoTalk’s användarvillkor för att kunna verifiera påståenden som att “[. . . ] Kakao’s server is unable to decrypt the encryption [. . . ]” från ett tekniskt perspektiv. Det huvudsakliga syftet med denna studien är att belysa hur olika brister i en produkt sammantagna kan skapa en risk för allvarliga vektorattacker mot end-to-end integriteten även fast det finns flera skyddslager. Mer specifikt visar vi hur en central katalogserver för public-keys gör end-to-end krypteringssystemet sårbart mot välkända operator-site man-in-the-middle-attacker. Trots att denna naiva typ av attack kan verka uppenbar, argumenterar vi för att (KakaoTalk) användare borde veta om styrkorna och svagheterna med en särskild systemdesign för att kunna göra ett informerat val för om de ska lita på säkerheten hos en chattapplikation eller inte.

Spreadsheets are routinely used in business and scientific contexts, and one of the most vexing challenges data analysts face is performing data cleaning prior to analysis and evaluation. The ad-hoc and arbitrary nature of data cleaning problems, such as typos, inconsistent formatting, missing values, and a lack of standardization, often creates the need for highly specialized pipelines. We ask whether an LLM can find its way around a spreadsheet and how to support end-users in taking their free-form data processing requests to fruition. Just like RAG retrieves context to answer users' queries, we demonstrate how we can retrieve elements from a code library to compose data processing pipelines. Through comprehensive experiments, we demonstrate the quality of our system and how it is able to continuously augment its vocabulary by saving new codes and pipelines back to the code library for future retrieval. / Master of Science / Spreadsheets are frequently utilized in both business and scientific settings, and one of the most challenging tasks that must be accomplished before analysis and evaluation can take place is the cleansing of the data. The ad-hoc and arbitrary nature of issues in data quality, such as typos, inconsistent formatting, missing values, and lack of standardization, often creates the need for highly specialized data cleaning pipelines. Within the scope of this thesis, we investigate whether a large language model (LLM) can navigate its way around a spreadsheet, as well as how to assist end-users in bringing their free-form data processing requests to fruition. Just like Retrieval-Augmented Generation (RAG) retrieves context to answer user queries, we demonstrate how we can retrieve elements from a Python code reference to compose data processing pipelines. Through comprehensive experiments, we showcase the quality of our system and how it is capable of continuously improving its code-writing ability by saving new codes and pipelines back to the code library for future retrieval.

Experimental and analytical research has been conducted to develop unified design procedures for eight extended end-plate moment connection configurations subject to cyclic/seismic loading. In addition, the suitability of extended end-plate moment connections for use in seismic force resisting moment frames was investigated. Eleven full-scale cyclic and nine monotonic extended end-plate moment connection tests were conducted. Design procedures for determining the required bolt diameter and grade, end-plate thickness, and column flange thickness were developed. The proposed design procedure utilizes a strong column, strong connection, and weak beam design philosophy. This forces the connecting beam to provide the required inelastic deformations through formation of a plastic hinge adjacent to the connection region. The proposed design procedure was used to make comparisons with ninety experimental tests conducted over the past twenty-six years. A limited finite element study was conducted to investigate the behavior of the column flange. The experimental results demonstrate that extended end-plate moment connections can be detailed and designed to be suitable for use in seismic force resisting moment frames. The proposed design procedure strength predictions correlated well with the results from ninety experimental tests. The limited finite element modeling conducted as a part of this study, correlated well with the strength predictions produced by the proposed design procedure. / Ph. D.