Commerce Lab: Mission analysis. Payload integration study

The objectives of the commerce lab mission analysis and payload integration study are discussed. A mission model which accommodates commercial users and provides a basic data base for future mission planning is described. The data bases developed under this study include: (1) user requirements; (2) apparatus capabilities and availabilities; and (3) carrier capabilities. These data bases are synthesized in a trades and analysis phase along with the STS flight opportunities. Optimum missions are identified

Progress and challenges in modeling turbulent aerodynamic flows

Progress in modeling external aerodynamic flows achieved by using computations and experiments designed to guide turbulence modeling is presented. The computational procedures emphasize utilization of the Reynolds-averaged Navier-Stokes equations and various statistical modeling approaches. Developments for including the influence of compressibility are provided; they point up some of the complexities involved in modeling high-speed flows. Examples of complementary studies that provide the status, limitations, and future challenges of modeling for transonic, supersonic, and hypersonic flows are given

Wind tunnel requirements for computational fluid dynamics code verification

The role of experiment in the development of Computational Fluid Dynamics (CFD) for aerodynamic flow field prediction is discussed. Requirements for code verification from two sources that pace the development of CFD are described for: (1) development of adequate flow modeling, and (2) establishment of confidence in the use of CFD to predict complex flows. The types of data needed and their accuracy differs in detail and scope and leads to definite wind tunnel requirements. Examples of testing to assess and develop turbulence models, and to verify code development, are used to establish future wind tunnel testing requirements. Versatility, appropriate scale and speed range, accessibility for nonintrusive instrumentation, computerized data systems, and dedicated use for verification were among the more important requirements identified

A CFD validation roadmap for hypersonic flows

A roadmap for computational fluid dynamics (CFD) code validation is developed. The elements of the roadmap are consistent with air-breathing vehicle design requirements and related to the important flow path components: forebody, inlet, combustor, and nozzle. Building block and benchmark validation experiments are identified along with their test conditions and measurements. Based on an evaluation criteria, recommendations for an initial CFD validation data base are given and gaps identified where future experiments would provide the needed validation data

Accuracy requirements and benchmark experiments for CFD validation

The role of experiment in the development of Computation Fluid Dynamics (CFD) for aerodynamic flow prediction is discussed. The CFD verification is a concept that depends on closely coordinated planning between computational and experimental disciplines. Because code applications are becoming more complex and their potential for design more feasible, it no longer suffices to use experimental data from surface or integral measurements alone to provide the required verification. Flow physics and modeling, flow field, and boundary condition measurements are emerging as critical data. Four types of experiments are introduced and examples given that meet the challenge of validation: flow physics experiments; flow modeling experiments; calibration experiments; and verification experiments. Measurement and accuracy requirements for each of these differ and are discussed. A comprehensive program of validation is described, some examples given, and it is concluded that the future prospects are encouraging

Asymmetric soft-error resistant memory

A memory system is provided, of the type that includes an error-correcting circuit that detects and corrects, that more efficiently utilizes the capacity of a memory formed of groups of binary cells whose states can be inadvertently switched by ionizing radiation. Each memory cell has an asymmetric geometry, so that ionizing radiation causes a significantly greater probability of errors in one state than in the opposite state (e.g., an erroneous switch from '1' to '0' is far more likely than a switch from '0' to'1'. An asymmetric error correcting coding circuit can be used with the asymmetric memory cells, which requires fewer bits than an efficient symmetric error correcting code

Financial deregulation, monetary policy, and central banking

The paper analyzes the need for financial regulations in the implementation of central bank policy. It emphasizes that a central bank serves two functions. Central banks function as monetary authorities, managing high-powered money to influence the price level and real activity; and they engage in regular and emergency lending to financial institutions. The authors term these functions monetary and banking policies, respectively. They emphasize that regulations are not essential for the execution of monetary policy because high-powered money can be managed with open market operations in government bonds. By its very nature, however, banking policy involves a swap of government securities for claims on individual banks. Just as private lenders must restrict and monitor individual borrowers, a central bank must regulate and supervise the institutions that borrow from it. Virtually all economists agree that there is an important role for monetary policy to stabilize prices and real activity. Banking policy has been rationalized as a source of funds for temporarily illiquid but solvent banks. To assess that rationale, the authors develop the distinction between illiquidity and insolvency in detail, showing the distinction to be meaningful precisely because information about the value of bank assets is incomplete and costly to obtain. Nevertheless, they explain why the cost of information per se cannot rationalize banking policy. On the basis of such considerations, they find it difficult to make a case for banking policy and the regulatory and supervisory activities that support it.Bank supervision ; Monetary policy ; Banks and banking, Central

Financial deregulation, monetary policy, and central banking

The paper analyzes the need for financial regulations in the implementation of central bank policy. It emphasizes that a central bank serves two functions. Central banks function as monetary authorities, managing high-powered money to influence the price level and real activity; and they engage in regular and emergency lending to financial institutions. The authors term these functions monetary and banking policies, respectively. They emphasize that regulations are not essential for the execution of monetary policy because high-powered money can be managed with open market operations in government bonds. By its very nature, however, banking policy involves a swap of government securities for claims on individual banks. Just as private lenders must restrict and monitor individual borrowers, a central bank must regulate and supervise the institutions that borrow from it. Virtually all economists agree that there is an important role for monetary policy to stabilize prices and real activity. Banking policy has been rationalized as a source of funds for temporarily illiquid but solvent banks. To assess that rationale, the authors develop the distinction between illiquidity and insolvency in detail, showing the distinction to be meaningful precisely because information about the value of bank assets is incomplete and costly to obtain. Nevertheless, they explain why the cost of information per se cannot rationalize banking policy. On the basis of such considerations, they find it difficult to make a case for banking policy and the regulatory and supervisory activities that support it.Bank supervision ; Monetary policy ; Banks and banking, Central

Bootstrap Approximations in Contractor Renormalization

We propose a bootstrap method for approximating the long-range terms in the Contractor Renormalization (CORE) method. The idea is tested on the 2-D Heisenberg antiferromagnet and the frustrated J_2-J_1 model. We obtain renormalization group flows that directly reveal the Neel phase of the unfrustrated HAF and the existence of a phase transition in the J_2-J_1 model for weak frustration. However, we find that this bootstrap method is dependent on blocking and truncation schemes. For this reason, we discuss these dependencies and unresolved issues that researchers who use this approach must consider.Comment: Some clarifications added for Phys Rev submissio