All the Inbent Fractals of Connection

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Turbulent Skin Friction at High Reynolds Numbers and Low Supersonic Velocities

Turbulent skin friction at high Reynolds number and low supersonic speed

TriCheck: Memory Model Verification at the Trisection of Software, Hardware, and ISA

Memory consistency models (MCMs) which govern inter-module interactions in a shared memory system, are a significant, yet often under-appreciated, aspect of system design. MCMs are defined at the various layers of the hardware-software stack, requiring thoroughly verified specifications, compilers, and implementations at the interfaces between layers. Current verification techniques evaluate segments of the system stack in isolation, such as proving compiler mappings from a high-level language (HLL) to an ISA or proving validity of a microarchitectural implementation of an ISA. This paper makes a case for full-stack MCM verification and provides a toolflow, TriCheck, capable of verifying that the HLL, compiler, ISA, and implementation collectively uphold MCM requirements. The work showcases TriCheck's ability to evaluate a proposed ISA MCM in order to ensure that each layer and each mapping is correct and complete. Specifically, we apply TriCheck to the open source RISC-V ISA, seeking to verify accurate, efficient, and legal compilations from C11. We uncover under-specifications and potential inefficiencies in the current RISC-V ISA documentation and identify possible solutions for each. As an example, we find that a RISC-V-compliant microarchitecture allows 144 outcomes forbidden by C11 to be observed out of 1,701 litmus tests examined. Overall, this paper demonstrates the necessity of full-stack verification for detecting MCM-related bugs in the hardware-software stack.Comment: Proceedings of the Twenty-Second International Conference on Architectural Support for Programming Languages and Operating System

A phase one AR/C system design

The Phase One AR&C System Design integrates an evolutionary design based on the legacy of previous mission successes, flight tested components from manned Rendezvous and Proximity Operations (RPO) space programs, and additional AR&C components validated using proven methods. The Phase One system has a modular, open architecture with the standardized interfaces proposed for Space Station Freedom system architecture

Quantum orbital angular momentum of elliptically-symmetric light

We present a quantum mechanical analysis of the orbital angular momentum of a class of recently discovered elliptically-symmetric stable light fields --- the so-called Ince-Gauss modes. We study, in a fully quantum formalism, how the orbital angular momentum of these beams varies with their ellipticity and discover several compelling features, including: non-monotonic behavior, stable beams with real continuous (non-integer) orbital angular momenta, and orthogonal modes with the same orbital angular momenta. We explore, and explain in detail, the reasons for this behavior. These features may have application to quantum key distribution, atom trapping, and quantum informatics in general --- as the ellipticity opens up a new way of navigating the photonic Hilbert space.Comment: 9 Pages, 4 Figures, Comments Welcom

Electrostatic internal energy using the method of images

For several configurations of charges in the presence of conductors, the method of images permits us to obtain some observables associated with such a configuration by replacing the conductors with some image charges. However, simple inspection shows that the potential energy associated with both systems does not coincide. Nevertheless, it can be shown that for a system of a grounded or neutral conductor and a distribution of charges outside, the external potential energy associated with the real charge distribution embedded in the field generated by the set of image charges is twice the value of the internal potential energy associated with the original system. This assertion is valid for any size and shape of the conductor, and regardless of the configuration of images required. In addition, even in the case in which the conductor is not grounded nor neutral, it is still possible to calculate the internal potential energy of the original configuration through the method of images. These results show that the method of images could also be useful for calculations of the internal potential energy of the original system.Comment: 5 pages, 3 figures. New discussions added. Minor change

Lasing from a circular Bragg nanocavity with an ultra-small modal volume

We demonstrate single-mode lasing at telecommunication wavelengths from a circular nanocavity employing a radial Bragg reflector. Ultra-small modal volume and Sub milliwatt pump threshold level are observed for lasers with InGaAsP quantum well active membrane. The electromagnetic field is shown to be tightly confined within the 300nm central pillar of the cavity. The quality factors of the resonator modal fields are estimated to be on the order of a few thousands.Comment: 3 pages, 4 figures Submitted to AP

Aerodynamic Design of Axial-Flow Compressors. VII - Blade-Element Flow in Annular Cascades

Annular blade-element data obtained primarily from single-stage compressor installations are correlated over a range of inlet Mach numbers and cascade geometry. The correlation curves are presented in such a manner that they are related directly to the low-speed two-dimensional-cascade data of part VI of this series. Thus, the data serve as both an extension and a verification of the two-dimensional-cascade data. In addition, the correlation results are applied to compressor design

Accounting as a mechanism of governmentality in the creation of a British hospital system

This thesis is historical in nature. It adopts a methodology that has recently taken the study of accounting history into the arena of the social; leaving behind tradi- tional notions of accounting as being only what accountants do. The focus of the study is on the annual reporting of activity, in terms of both its nancial and phys- ical dimensions, in the history of the British voluntary hospital movement. The study is highly contextualised. By adopting this approach it has been possible to show how accounting reports initially enabled the managers of medical institutions to reverse the focus of accountability onto those charitable individuals that were providing the funding for the hospitals. This greatly strengthened the fundrais- ing capacity of the hospital, while simultaneously de ecting attention away from the e cacy of the institution itself. Later, however, it is shown that after various abortive or only partially successful attempts, it was possible, through the medium of a uniform accounting system, to return the focus of accountability back onto the management of the hospitals. It is important to note that the success of this movement was contingent less on the quality or viability of the accounting system than the legitimacy of the organisation that published its results. Until this legit- imacy was established in the minds of the users of the accounts the e ects of the accounting was severely limited. Once it was rmly established the accounts be- came a powerful knowledge technology that enabled a substantial degree of control to be exercised over hospitals, such that a `quasi-system' of hospitals was created