A tabulation of pipe length to diameter ratios as a function of Mach number and pressure ratios for compressible flow

Computer programs and resulting tabulations are presented of pipeline length-to-diameter ratios as a function of Mach number and pressure ratios for compressible flow. The tabulations are applicable to air, nitrogen, oxygen, and hydrogen for compressible isothermal flow with friction and compressible adiabatic flow with friction. Also included are equations for the determination of weight flow. The tabulations presented cover a wider range of Mach numbers for choked, adiabatic flow than available from commonly used engineering literature. Additional information presented, but which is not available from this literature, is unchoked, adiabatic flow over a wide range of Mach numbers, and choked and unchoked, isothermal flow for a wide range of Mach numbers

Runtime Verification of Temporal Properties over Out-of-order Data Streams

We present a monitoring approach for verifying systems at runtime. Our approach targets systems whose components communicate with the monitors over unreliable channels, where messages can be delayed or lost. In contrast to prior works, whose property specification languages are limited to propositional temporal logics, our approach handles an extension of the real-time logic MTL with freeze quantifiers for reasoning about data values. We present its underlying theory based on a new three-valued semantics that is well suited to soundly and completely reason online about event streams in the presence of message delay or loss. We also evaluate our approach experimentally. Our prototype implementation processes hundreds of events per second in settings where messages are received out of order.Comment: long version of the CAV 2017 pape

Telemedicine and Healthcare Implications for Central Virginia: A Systematic Review of the Literature

Background: Uncertainties and challenges associated with COVID-19 have affected the efficient delivery of health care in Central Virginia. Integrating and redesigning health systems could boost the quality and efficiency of care delivery. Telemedicine has been suggested as a viable solution to increase virtual access to patient advocacy healthcare education and training programs and has the potential to help facilitate the delivery of health services to rural and remote areas. It is projected that access to quality telehealth services can minimize the need for in-person hospital visitation amid the pandemic. The innovation also facilitates remote assessment of patients and monitoring of patient illness and treatment. For the rural population at risk of COVID-19 or any easily transmissible infection, telemedicine can provide convenient access to routine care without provider-patient contact, thus limiting the spread of the virus. Methods: A systematic literature review of peer-reviewed and grey literature was conducted. The authors used electronic databases including Embase, PubMed, CINAHIL and Web of Science to locate and access relevant articles based on their inclusion criteria. Studies were selected that investigated the implementation of telemedicine in the clinical and educational healthcare settings in rural or remote locations within the United States. Forty articles were identified for review. The identified articles were published between 2010 and 2021 that were used in the study. Results: There was no significant literature on telemedicine utilization in the Commonwealth of Virginia. Additionally, there were limited studies on rural and remote settings that utilized telehealth services during the COVID-19 pandemic. Evidence suggested that telemedicine could improve access to healthcare services and enable providers to monitor patients from a distance. Researchers identified six key factors associated with telemedicine\u27s success and sustainability: education, training, vision, ownership, adaptability, economics, efficiency, and equipment. Conclusions: Rural and remote communities experience healthcare disparities and poor patient outcomes due to limited access to quality care and inequalities in education, training, and resource allocation. A deficiency of technological skills, knowledge and or resistance to change may prevent a quality telehealth program from being able to serve patients adequately

An Experimental Study of Combustor Exit Profile Shapes on Endwall Heat Transfer in High Pressure Turbine Vanes

The design and development of current and future gas turbine engines for aircraft propulsio

An Experimental Study of Combustor Exit Profile Shapes on Endwall Heat Transfer in High Pressure Turbine Vanes

ABSTRACT The design and development of current and future gas turbine engines for aircraft propulsion have focused on operating the high pressure turbine at increasingly elevated temperatures and pressures. The drive towards thermal operating conditions near theoretical stoichiometric limits as well as increasingly stringent requirements on reducing harmful emissions, both equate to the temperature profiles exiting combustors and entering turbines becoming less peaked than in the past. This drive has placed emphasis on determining how different types of inlet temperature and pressure profiles affect the first stage airfoil endwalls. The goal of the current study was to investigate how different radial profiles of temperature and pressure affect the heat transfer along the vane endwall in a high pressure turbine. Testing was performed in the Turbine Research Facility located at the Air Force Research Laboratory using an inlet profile generator. Results indicate that the convection heat transfer coefficients are influenced by both the inlet pressure profile shape and the location along the endwall. The heat transfer driving temperature for inlet profiles that are nonuniform in temperature is also discussed. INTRODUCTION The performance and durability of the hot section within gas turbine engines are critical operational issues that present many design and research challenges. The hot section of these engines includes both the combustion chamber and the high pressure turbine, the latter of which includes the endwall regions under investigation in this study. Considering that the hot gas temperatures are well above the melting point of the metal turbine hardware, the heat transfer to and aerodynami

Runtime verification of parametric properties using SMEDL

Parametric properties are typical properties to be checked in runtime verification (RV). As a common technique for parametric monitoring, trace slicing divides an execution trace into a set of sub traces which are checked against non-parametric base properties. An efficient trace slicing algorithm is implemented in MOP. Another RV technique, QEA further allows for nested use of universal and existential quantification over parameters. In this paper, we present a methodology for parametric monitoring using the RV framework SMEDL. Trace slicing algorithm in MOP can be expressed by execution of a set of SMEDL monitors. Moreover, the semantics of nested quantifiers is encoded by a hierarchy of monitors for aggregating verdicts of sub traces. Through case studies, we demonstrate that SMEDL provides a natural way to monitor parametric properties with more potentials for flexible deployment and optimizations

A foundation for runtime monitoring

Runtime Verification is a lightweight technique that complements other verification methods in an effort to ensure software correctness. The technique poses novel questions to software engineers: it is not easy to identify which specifications are amenable to runtime monitor-ing, nor is it clear which monitors effect the required runtime analysis correctly. This exposition targets a foundational understanding of these questions. Particularly, it considers an expressive specification logic (a syntactic variant of the modal μ-calculus) that is agnostic of the verification method used, together with an elemental framework providing an operational semantics for the runtime analysis performed by monitors. The correspondence between the property satisfactions in the logic on the one hand, and the verdicts reached by the monitors performing the analysis on the other, is a central theme of the study. Such a correspondence underpins the concept of monitorability, used to identify the subsets of the logic that can be adequately monitored for by RV. Another theme of the study is that of understanding what should be expected of a monitor in order for the verification process to be correct. We show how the monitor framework considered can constitute a basis whereby various notions of monitor correctness may be defined and investigated.peer-reviewe

A Foundation for Runtime Monitoring

Runtime Verification is a lightweight technique that complements other verification methods in an effort to ensure software correctness. The technique poses novel questions to software engineers: it is not easy to identify which specifications are amenable to runtime monitoring, nor is it clear which monitors effect the required runtime analysis correctly. This exposition targets a foundational understanding of these questions. Particularly, it considers an expressive specification logic (a syntactic variant of the mmucalc) that is agnostic of the verification method used, together with an elemental framework providing an operational semantics for the runtime analysis performed by monitors. The correspondence between the property satisfactions in the logic on the one hand, and the verdicts reached by the monitors performing the analysis on the other, is a central theme of the study. Such a correspondence underpins the concept of monitorability, used to identify the subsets of the logic that can be adequately monitored for by RV. Another theme of the study is that of understanding what should be expected of a monitor in order for the verification process to be correct. We show how the monitor framework considered can constitute a basis whereby various notions of monitor correctness may be defined and investigated