Composite ceramics

Issued as Progress status and management reports [nos. 1-8], Draft final technical report, and Final technical report, Project E-18-X2

Quantitative information-flow tracking for real systems

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 99-105).An information-flow security policy constrains a computer system's end-to-end use of information, even as it is transformed in computation. For instance, a policy would not just restrict what secret data could be revealed directly, but restrict any output that might allow inferences about the secret. Expressing such a policy quantitatively, in terms of a specific number of bits of information, is often an effective program independent way of distinguishing what scenarios should be allowed and disallowed. This thesis describes a family of new techniques for measuring how much information about a program's secret inputs is revealed by its public outputs on a particular execution, in order to check a quantitative policy on realistic systems. Our approach builds on dynamic tainting, tracking at runtime which bits might contain secret in formation, and also uses static control-flow regions to soundly account for implicit flows via branches and pointer operations. We introduce a new graph model that bounds information flow by the maximum flow between inputs and outputs in a flow network representation of an execution. The flow bounds obtained with maximum flow are much more precise than those based on tainting alone (which is equivalent to graph reachability). The bounds are a conservative estimate of channel capacity: the amount of information that could be transmitted by an adversary making an arbitrary choice of secret inputs. We describe an implementation named Flowcheck, built using the Valgrind framework for x86/Linux binaries, and use it to perform case studies on six real C, C++, and Objective C programs, three of which have more than 250,000 lines of code. We used the tool to check the confidentiality of a different kind of information appropriate to each program. Its results either verified that the information was appropriately kept secret on the examined executions, or revealed unacceptable leaks, in one case due to a previously unknown bug.by Stephen Andrew McCamant.Ph.D

The Telecommunications and Data Acquisition Report

Archival reports are given on developments in programs managed by JPL's Office of Telecommunications and Data Acquisition (TDA), including space communications, radio navigation, radio science, ground-based radio and radar astronomy, and the Deep Space Network (DSN) and its associated Ground Communications Facility (GCF) in planning, supporting research and technology, implementation, and operations. Also included is TDA-funded activity at JPL on data and information systems and reimbursable DSN work performed for other space agencies through NASA. In the search for extraterrestrial intelligence (SETI), implementation and operations for searching the microwave spectrum are reported. Use of the Goldstone Solar System Radar for scientific exploration of the planets, their rings and satellites, asteroids, and comets are discussed

Robust and stable discrete adjoint solver development for shape optimisation of incompressible flows with industrial applications

PhD, 156ppThis thesis investigates stabilisation of the SIMPLE-family discretisations for incompressible flow and their discrete adjoint counterparts. The SIMPLE method is presented from typical \prediction-correction" point of view, but also using a pressure Schur complement approach, which leads to a wider class of schemes. A novel semicoupled implicit solver with velocity coupling is proposed to improve stability. Skewness correction methods are applied to enhance solver accuracy on non-orthogonal grids. An algebraic multi grid linear solver from the HYPRE library is linked to flow and discrete adjoint solvers to further stabilise the computation and improve the convergence rate. With the improved implementation, both of flow and discrete adjoint solvers can be applied to a wide range of 2D and 3D test cases. Results show that the semi-coupled implicit solver is more robust compared to the standard SIMPLE solver. A shape optimisation of a S-bend air flow duct from a VW Golf vehicle is studied using a CAD-based parametrisation for two Reynolds numbers. The optimised shapes and their flows are analysed to con rm the physical nature of the improvement. A first application of the new stabilised discrete adjoint method to a reverse osmosis (RO) membrane channel flow is presented. A CFD model of the RO membrane process with a membrane boundary condition is added. Two objective functions, pressure drop and permeate flux, are evaluated for various spacer geometries such as open channel, cavity, submerged and zigzag spacer arrangements. The flow and the surface sensitivity of these two objective functions is computed and analysed for these geometries. An optimisation with a node-base parametrisation approach is carried out for the zigzag con guration channel flow in order to reduce the pressure drop. Results indicate that the pressure loss can be reduced by 24% with a slight reduction in permeate flux by 0.43%.Queen Mary-China Scholarship Council Co-funded Scholarship No. 201206280018

Antenna array calibration in wireless communications

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Theoretical And Experimental Investigation On Turbine Aerodynamics And Heat Transfer Part I: Development Of A New Unsteady Transition Model Based On The Universal Intermittency Function Part II: Experimental and Numerical Investigations Of Filmcooling Effectiveness On A Highly Loaded Turbine Blade Under Steady/Unsteady Flow Condition

The flow around a gas turbine blade is inherently three-dimensional and based on the Re-number and the blade geometry, it may be laminar, transitional or turbulent. The blade surfaces are subject to periodic unsteady wakes that originate from the upstream stator/rotor rows. The wakes with their highly vortical cores impinge on the downstream blade surfaces and cause an intermittent transition of the boundary layer from laminar to turbulent. The intermittent behavior of the boundary layer under periodic wake flow condition is characterized in several publications from TPFL (Turbomachinery Performance and Flow Research Lab). Intermittency at each location varies between a maximum and a minimum value at different times. Maximum intermittency corresponds to the intermittent behavior of the flow inside the blade boundary layer once it is subjected to the wake vortical core and minimum intermittency characterizes the nature of the boundary layer when it is subject to non-turbulent flow region between the wakes. The correlation between minimum, maximum and instantaneous intermittencies is best described by the universal intermittency function that has a Gaussian distribution. In the current study, a transport equation for intermittency has been derived from previously obtained experimental measurements. This transport equation is revisited for the curvilinear coordinate system and was implemented in a RANS solver to model the transient behavior of the flow on the suction surface of a turbine blade. It was later integrated with a turbulence model, and the results were validated against experimental measurements and transitional-SST turbulence model. The benchmark data, used for derivation and validation, were obtained in the cascade facility at TPFL. The facility simulates the periodic wake flow by moving rods attached to two parallel timing belts in front of the blade cascade. All calculations were conducted at Reynolds number of 414,000. Also, another effort has been made to measure film-cooling effectiveness on the suction and pressure surfaces of a low-pressure turbine blade utilizing the same cascade facility. Low-pressure turbine blades are not necessarily exposed to critically high temperatures and for that reason, cooling technologies are not very common in these stages of the engine. Yet, the film-cooling experiments were designed with the purpose of understanding the effects of the underlying physics of the transitional flow on filmcooling effectiveness. The flow around this turbine blade has unique characteristics. The flow regime is transitional and, especially in off-design conditions, it is often accompanied by flow separation and rapid change of pressure gradient as well as unsteady incoming wakes that could impinge on the blade surface and penetrate the boundary layer. These flow features add to the level of complexity of this case. For the experiments, the flow coefficient is maintained at 0.8, and the incoming wakes in experiments have a reduced frequency of 3.18. Film-cooling effectiveness under periodic unsteady flow condition was studied using Pressure-Sensitive Paint. Experiments were performed at Reynolds number of 150,000 and blowing ratio of 1, based on equal mass flux distribution. It was determined that HTC and FCE behave in opposite manners for the most part. This behavior is justified from turbulence intensity and velocity fluctuation perspective. Also, unsteady wakes show opposite effects on suction and pressure sides of the blade

Space programs summary no. 37-37, volume IV for the period December 1, 1965 to January 31, 1966. Supporting research and advanced development

Guidance and control, engineering development, environmental simulation, jet propulsion, space science, and telecommunication

A computer-aided design for digital filter implementation

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